WorldWideScience

Sample records for neutral gas outflows

  1. Outflows of neutral (and ionized) gas in radio galaxies

    OpenAIRE

    Morganti, R.; Oosterloo, T.; Tadhunter, C.

    2004-01-01

    Outflows up to 1500 km/s of atomic neutral hydrogen are detected in a growing number of radio galaxies. Outflows with similar velocities are also detected in ionized gas, suggesting a common origin for the extreme kinematics of these two phases of the gas. The high detection rate ofsuch outflows in young (or restarted) radio sources appears to be related to the existence of a dense ISM around these objects. Such a dense ISM can have important consequences for the evolution of the radio source...

  2. Outflows of neutral (and ionized) gas in radio galaxies

    CERN Document Server

    Morganti, R; Tadhunter, C

    2004-01-01

    Outflows up to 1500 km/s of atomic neutral hydrogen are detected in a growing number of radio galaxies. Outflows with similar velocities are also detected in ionized gas, suggesting a common origin for the extreme kinematics of these two phases of the gas. The high detection rate ofsuch outflows in young (or restarted) radio sources appears to be related to the existence of a dense ISM around these objects. Such a dense ISM can have important consequences for the evolution of the radio source and the galaxy as a whole. Here we summarize the recent results obtained and the characteristics derived so far for these outflows. We also discuss possible mechanisms (e.g. interaction between the radio plasma and the ISM and adiabatically expanding broad emission lines clouds) that can be at the origin of these phenomena.

  3. Fast outflow of neutral and ionized gas from the radio galaxy 3C 293

    NARCIS (Netherlands)

    Emonts, B.H.C.; Morganti, R.; Oosterloo, T.A.; Tadhunter, C.N.; Hulst, J.M. van der

    2005-01-01

    Abstract: We detect a fast outflow of neutral and ionized gas with velocities up to about 1000 km/s from the central region of radio galaxy 3C 293. With optical spectroscopy we locate the bulk of the ionized gas outflow at the position of a bright radio hot-spot in the inner radio jet, about 1 kpc e

  4. Fast outflow of neutral and ionized gas from the radio galaxy 3C 293

    NARCIS (Netherlands)

    Emonts, BHC; Morganti, R; Osterloo, TA; Tadhunter, CN; van der Hulst, JM; Braun, R

    2005-01-01

    We detect a fast outflow of neutral and ionized gas with velocities up to similar to 1000 km/s from the central region of radio galaxy 3C 293. With optical spectroscopy we locate the bulk of the ionized gas outflow at the position of a bright radio hot-spot in the inner radio jet, about I kpc east o

  5. Fast outflow of neutral and ionized gas from the radio galaxy 3C 293

    OpenAIRE

    Emonts, B. H. C.; Morganti, R.; Oosterloo, T A; Tadhunter, C.N.; van der Hulst, J. M.

    2005-01-01

    Abstract: We detect a fast outflow of neutral and ionized gas with velocities up to about 1000 km/s from the central region of radio galaxy 3C 293. With optical spectroscopy we locate the bulk of the ionized gas outflow at the position of a bright radio hot-spot in the inner radio jet, about 1 kpc east of the nucleus. Given the presence of large amounts of cold gas and the distorted morphology of the radio jet in this region, we argue that the ISM is pushed out by a severe interaction with th...

  6. Fast outflow of neutral and ionized gas from the radio galaxy 3C 293

    CERN Document Server

    Emonts, B H C; Oosterloo, T A; Tadhunter, C N; Van der Hulst, J M

    2005-01-01

    We detect a fast outflow of neutral and ionized gas with velocities up to about 1000 km/s from the central region of radio galaxy 3C 293. With optical spectroscopy we locate the bulk of the ionized gas outflow at the position of a bright radio hot-spot in the inner radio jet, about 1 kpc east of the nucleus. Given the presence of large amounts of cold gas and the distorted morphology of the radio jet in this region, we argue that the ISM is pushed out by a severe interaction with the radio plasma. The similarity of the outflow of HI with the ionized gas outflow that we see at the position of the radio hot-spot suggests that despite the high energies involved in the jet-ISM interaction, part of the gas stays, or becomes again, neutral. In this paper we also present the detection of HI emission in three nearby companions of 3C 293.

  7. Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

    CERN Document Server

    Cazzoli, S; Maiolino, R; Colina, L

    2016-01-01

    We studied the properties of the neutral gas in a sample of 38 local [U]LIRGs, which mainly covers the less explored LIRG luminosity range. This study is based on the analysis of the spatially integrated and spatially resolved spectra of the NaD feature obtained with the VIMOS/VLT-IFS. Analyzing spatially integrated spectra, we find that the contribution of stars to the observed NaD-EWs is generally small (<35%), and therefore this feature is dominated by ISM absorption. After subtracting the stellar contribution, we find that the pure-ISM integrated spectra generally show blueshifted NaD profiles, indicating neutral gas outflow velocities V in the range 65-260 km/s. Excluding galaxies with AGNs, V shows a dependency with the SFR of the type V \\propto SFR^0.15 (in rather good agreement with previous results). The spatially resolved analysis was performed for 40 galaxies, 22 of which have neutral gas velocity fields dominated by noncircular motions with signatures of cone-like winds. However, a modest numbe...

  8. Fast neutral outflows in nearby radio galaxies : a major source of feedback

    NARCIS (Netherlands)

    Morganti, R.; Tadhunter, C.; Oosterloo, T.; Holt, J.; Emonts, B.

    2007-01-01

    Abstract: Fast (~1000 km/s) outflows of neutral gas (from 21-cm HI absorption) are detected in strong radio sources. The outflows occur, at least in some cases, at distances from the radio core that range between few hundred parsecs and kpc. These HI outflows likely originate from the interaction be

  9. Fast neutral outflows in nearby radio galaxies: a major source of feedback

    CERN Document Server

    Morganti, R; Oosterloo, T; Holt, J; Emonts, B; Morganti, Raffaella; Tadhunter, Clive; Oosterloo, Tom; Holt, Joanna; Emonts, Bjorn

    2007-01-01

    Fast (~1000 km/s) outflows of neutral gas (from 21-cm HI absorption) are detected in strong radio sources. The outflows occur, at least in some cases, at distances from the radio core that range between few hundred parsecs and kpc. These HI outflows likely originate from the interaction between radio jets and the dense surrounding medium. The estimated mass outflow rates are comparable to those of moderate starburst-driven superwinds. The impact on the evolution of the host galaxies is discussed.

  10. Fast Neutral Outflows in Nearby Radio Galaxies: A Major Source of Feedback

    Science.gov (United States)

    Morganti, R.; Tadhunter, C.; Oosterloo, T.; Holt, J.; Emonts, B.

    2007-10-01

    Fast (˜ 1000 km/s) outflows of neutral gas (from 21-cm HI absorption) are detected in strong radio sources. The outflows occur, at least in some cases, at distances from the radio core that range between few hundred parsecs and kpc. These HI outflows likely originate from the interaction between radio jets and the dense surrounding medium. The estimated mass outflow rates are comparable to those of moderate starburst-driven superwinds. The impact on the evolution of the host galaxies is discussed.

  11. Fast neutral outflows in powerful radio galaxies: a major source of feedback in massive galaxies

    Science.gov (United States)

    Morganti, R.; Tadhunter, C. N.; Oosterloo, T. A.

    2005-12-01

    We report the detection of fast (~1000 km s-1), massive outflows of neutral gas observed - using the WSRT - as 21-cm H I absorption against the strong radio continuum of seven radio sources. The neutral outflows occur, in at least somes cases, at kpc distance from the nucleus, and they are most likely driven by the interactions between the expanding radio jets and the gaseous medium enshrouding the central regions. We estimate that the associated mass outflow rates are up to ~50 M⊙ yr-1, comparable (although at the lower end of the distribution) to the outflow rates found for starburst-driven superwinds in Ultra Luminous IR Galaxies (ULIRG). This suggests that massive, jet-driven outflows of neutral gas in radio-loud AGN can have as large an impact on the evolution of the host galaxies as the outflows associated with starbursts. A radio-loud phase of the AGN is likely a relatively common, albeit short, phase in the life of many (or even all) massive ellipticals. Jet-driven neutral outflows may represent one of the main feedback mechanisms in these galaxies.

  12. Fast neutral outflows in powerful radio galaxies: a major source of feedback in massive galaxies

    CERN Document Server

    Morganti, R; Oosterloo, T A

    2005-01-01

    We report the detection of fast (~ 1000 km/s), massive outflows of neutral gas observed -- using the WSRT -- as 21-cm HI absorption against the strong radio continuum of seven radio sources. The neutral outflows occur, in at least somes cases, at kpc distance from the nucleus, and they are most likely driven by the interactions between the expanding radio jets and the gaseous medium enshrouding the central regions. We estimate that the associated mass outflow rates are up to ~50 M_sun/yr, comparable (although at the lower end of the distribution) to the outflow rates found for starburst-driven superwinds in Ultra Luminous IR Galaxies (ULIRG). This suggests that massive, jet-driven outflows of neutral gas in radio-loud AGN can have as large an impact on the evolution of the host galaxies as the outflows associated with starbursts. A radio-loud phase of the AGN is likely a relatively common, albeit short, phase in the life of many (or even all) massive ellipticals. Jet-driven neutral outflows may represent one ...

  13. Radio jets and outflows of cold gas

    CERN Document Server

    Morganti, Raffaella

    2011-01-01

    Massive gas outflows are considered a key component in the process of galaxy formation and evolution. It is, therefore, not surprising that a lot of effort is going in quantifying their impact via detailed observations. This short contribution presents recent results obtained from HI and CO observations of different objects where the AGN - and in particular the radio jet - is likely playing an important role in producing the gas outflows. These preliminary results are reinforcing the conclusion that these outflows have a complex and multiphase structure where cold gas in different phases (atomic and molecular) is involved and likely represent a major component. These results will also provide important constraints for establishing how the interaction between AGN/radio jet and the surrounding ISM occurs and how efficiently the gas should cool to produce the observed properties of the outflowing gas. HI likely represents an intermediate phase in this process, while the molecular gas would be the final stage. Wh...

  14. A jet-induced outflow of warm gas in 3C 293

    CERN Document Server

    Emonts, B H C; Tadhunter, C N; Oosterloo, T A; Holt, J; Van der Hulst, J M

    2005-01-01

    Using long slit emission-line spectra we detect a fast outflow of ionized gas, with velocities up to 1000 km/s, in the nearby powerful radio galaxy 3C 293 (z = 0.045). The fast outflow is located about 1 kpc east of the nucleus, in a region of enhanced radio emission due to the presence of a distorted radio jet. We present results that indicate that this fast outflow is caused by a jet-ISM interaction. The kinematics of the outflowing ionized gas are very similar to those of a fast outflow of neutral hydrogen gas in this galaxy, suggesting that both outflows are the result of the same driving mechanism. While the mass of the outflowing ionized gas is about 1 x 10e5 M_sun, the total HI mass involved in the neutral outflow is about 100 times higher (10e7 M_sun). This shows that, despite the high energies that must be involved in driving the outflow, most of the gas remains, or becomes again, neutral. Other outflows of ionized gas, although not as pronounced as in the region of the enhanced radio emission, are a...

  15. Fast cold gas in hot AGN outflows

    CERN Document Server

    Costa, Tiago; Haehnelt, Martin

    2014-01-01

    Observations of the emission from spatially extended cold gas around bright high-redshift QSOs reveal surprisingly large velocity widths exceeding 2000 km s^(-1), out to projected distances as large as 30 kpc. The high velocity widths have been interpreted as the signature of powerful AGN-driven outflows. Naively, these findings appear in tension with hydrodynamic models in which AGN-driven outflows are energy-driven and thus very hot with typical temperatures T = 10^6-7 K. Using the moving-mesh code Arepo, we perform 'zoom-in' cosmological simulations of a z = 6 QSO and its environment, following black hole growth and feedback via energy-driven outflows. In the simulations, the QSO host galaxy is surrounded by a clumpy circum-galactic medium pre-enriched with metals due to supernovae-driven galactic outflows. As a result, part of the AGN-driven hot outflowing gas can cool radiatively, leading to large amounts (> 10^9 M_sun) of cold gas comoving with the hot bipolar outflow. This results in velocity widths of...

  16. The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

    Science.gov (United States)

    Bae, Hyun-Jin; Woo, Jong-Hak

    2016-09-01

    We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O iii] line profiles, e.g., narrow core and broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O iii] velocity-velocity dispersion distribution of ˜39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ˜500 to ˜1000 km s-1 for the majority of AGNs, and up to ˜1500-2000 km s-1 for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O iii] velocity to AGNs with positive [O iii] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.

  17. IC 5063 : AGN driven outflow of warm and cold gas

    NARCIS (Netherlands)

    Morganti, R.; Holt, J.; Saripalli, L.; Oosterloo, T. A.; Tadhunter, C. N.

    2007-01-01

    We present new ATCA 17- and 24- GHz radio images and ESO- NTT optical spectra of the radio- loud Seyfert galaxy IC 5063, the first galaxy in which a fast (similar to 600 km s(-1)) outflow of neutral hydrogen was discovered. The new radio data confirm the triple radio structure with a central, unreso

  18. The location of the broad HI absorption in 3C305: clear evidence for a jet-accelerated neutral outflow

    CERN Document Server

    Morganti, R; Tadhunter, C N; Van Moorsel, G; Emonts, B

    2005-01-01

    We present high-spatial resolution 21-cm HI VLA observations of the radio galaxy 3C305 (z=0.041). These new high-resolution data show that the ~1000 km/s broad HI absorption, earlier detected in low-resolution WSRT observations, is occurring against the bright, eastern radio lobe, about 1.6 kpc from the nucleus. We use new optical spectra taken with the WHT to make a detailed comparison of the kinematics of the neutral hydrogen with that of the ionised gas. The striking similarity between the complex kinematics of the two gas phases suggests that both the ionised gas and the neutral gas are part of the same outflow. Earlier studies of the ionised gas had already found evidence for a strong interaction between the radio jet and the interstellar medium at the location of the eastern radio lobe. Our results show that the fast outflow produced by this interaction also contains a component of neutral atomic hydrogen. The most likely interpretation is that the radio jet ionises the ISM and accelerates it to the hig...

  19. The location of the broad H i absorption in 3C 305: clear evidence for a jet-accelerated neutral outflow

    Science.gov (United States)

    Morganti, R.; Oosterloo, T. A.; Tadhunter, C. N.; van Moorsel, G.; Emonts, B.

    2005-08-01

    We present high-spatial resolution 21-cm H i VLA observations of the radio galaxy 3C 305 (z=0.041). These new high-resolution data show that the ˜ 1000 km s-1 broad H I absorption, earlier detected in low-resolution WSRT observations, is occurring against the bright, eastern radio lobe, about 1.6 kpc from the nucleus. We use new optical spectra taken with the WHT to make a detailed comparison of the kinematics of the neutral hydrogen with that of the ionised gas. The striking similarity between the complex kinematics of the two gas phases suggests that both the ionised gas and the neutral gas are part of the same outflow. Earlier studies of the ionised gas had already found evidence for a strong interaction between the radio jet and the interstellar medium at the location of the eastern radio lobe. Our results show that the fast outflow produced by this interaction also contains a component of neutral atomic hydrogen. The most likely interpretation is that the radio jet ionises the ISM and accelerates it to the high outflow velocities observed. Our observations demonstrate that, following this strong jet-cloud interaction, not all gas clouds are destroyed and that part of the gas can cool and become neutral. The mass outflow rate measured in 3C 305 is comparable, although at the lower end of the distribution, to that found in Ultra-Luminous IR galaxies. This suggests that AGN-driven outflows, and in particular jet-driven outflows, can have a similar impact on the evolution of a galaxy as starburst-driven superwinds.

  20. Tracing Inflows and Outflows with Absorption Lines in Circumgalactic Gas

    CERN Document Server

    Ford, Amanda Brady; Oppenheimer, Benjamin D; Katz, Neal; Kollmeier, Juna A; Thompson, Robert; Weinberg, David H

    2013-01-01

    We examine how HI and metal absorption lines within low-redshift galaxy halos trace the dynamical state of circumgalactic gas, using cosmological hydrodynamic simulations that include a well-vetted heuristic model for galactic outflows. We categorize inflowing, outflowing, and ambient gas based on its history and fate as tracked in our simulation. Following our earlier work showing that the ionisation level of absorbers was a primary factor in determining the physical conditions of absorbing gas, we show here that it is also a governing factor for its dynamical state. Low-ionisation metal absorbers (e.g. MgII) tend to arise in gas that will fall onto galaxies within several Gyr, while high-ionisation metal absorbers (e.g. OVI) generally trace material that was deposited by outflows many Gyr ago. Inflowing gas is dominated by enriched material that was previously ejected in an outflow, hence accretion at low redshifts is typically substantially enriched. Recycling wind material is preferentially found closer t...

  1. HYDROGEN NEUTRAL OUTFLOWING DISKS OF B[E] SUPERGIANTS

    Directory of Open Access Journals (Sweden)

    M. Kraus

    2008-01-01

    Full Text Available Hemos modelado la línea [Oi] de emisión en la supergigante B[e] R126 en la LMC asumiendo un disco con flujo de masa. Encontramos que el hidrógeno en el disco debe estar ionizado al menos un 0.1%, lo que implica que el material del disco debe ser predominantemente neutral. La emisión libre-libre se calcula del viento polar y el contraste mínimo de densidad entre el viento polar y del disco debe ser de - 10.

  2. The Prevalence of Ionized Gas Outflows in Type 2 AGNs II. 3-D Biconical Outflow Models

    CERN Document Server

    Bae, Hyun-Jin

    2016-01-01

    We present 3-D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3-D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shift with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O III] line profiles, e.g., a narrow core and a broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O III] velocity-velo...

  3. The outflow of gas from the Centaurus A circumnuclear disk: atomic spectral line maps from Herschel-PACS and APEX

    CERN Document Server

    Israel, F P; Meijerink, R; Requena-Torres, M A; Stutzki, J

    2016-01-01

    The physical state of the gas in the central 500 pc of NGC~5128 (the radio galaxy Centaurus A - Cen A), was investigated using the far-infrared fine-structure lines of carbon, oxygen, and nitrogen, as well as the CO(4-3) molecular line. The circumnuclear disk (CND) is traced by emission from dust and the neutral gas ([CI] and CO). A gas outflow with a line-of-sight velocity of 60 km/s is evident in both species. The center of the CND is bright in [OI], [OIII], and [CII]; [OI]63mu emission dominates that of [CII] even though it is absorbed with optical depths of 1.0-1.5. The outflow is well-traced by the [NII] and [NIII] lines and also seen in the [CII] and [OIII] lines that peak in the center. Ionized gas densities are moderate in the CND and low everywhere else. Neutral gas densities range from 4000 per cm3 (outflow, extended thin disk ETD) to 20 000 per cm3 (CND). The CND radiation field is weak compared to the ETD starburst field. The outflow has a much stronger radiation field. The total mass of all the C...

  4. The outflow of gas from the Centaurus A circumnuclear disk. Atomic spectral line maps from Herschel/PACS and APEX

    Science.gov (United States)

    Israel, F. P.; Güsten, R.; Meijerink, R.; Requena-Torres, M. A.; Stutzki, J.

    2017-02-01

    The physical state of the gas in the central 500 pc of NGC 5128 (the radio galaxy Centaurus A), was investigated using the fine-structure lines of carbon [CI], [CII]; oxygen [OI], [OIII], and nitrogen [NII], [NIII] as well as the 12CO(4-3) molecular line. The circumnuclear disk (CND) is traced by emission from dust and the neutral gas ([CI] and 12CO). A gas outflow with a line-of-sight velocity of 60 km s-1 is evident in both lines. The [CI] emission from the CND is unusually strong with respect to that from CO. The center of the CND (R mass of all the CND gas is 9.1 ± 0.9×107M⊙ but the mass of the outflowing gas is only 15-30% of that. The outflow most likely originates from the shock-dominated CND cavity surrounding the central black hole. With a factor of three uncertainty, the mass outflow rate is ≈ 2 M⊙ yr-1, a thousand times higher than the accretion rate of the black hole. Without replenishment, the CND will be depleted in 15-120 million years. However, the outflow velocity is well below the escape velocity.

  5. The Prevalence of Gas Outflows in Type 2 AGNs

    CERN Document Server

    Woo, Jong-Hak; Son, Donghoon; Karouzos, Marios

    2015-01-01

    To constrain the nature and fraction of the ionized gas outflows in AGNs, we perform a detailed analysis on gas kinematics as manifested by the velocity dispersion and shift of the OIII {\\lambda}5007 emission line, using a large sample of ~39,000 type 2 AGNs at z<0.3. First, we confirm a broad correlation between OIII and stellar velocity dispersions, indicating that the bulge gravitational potential plays a main role in determining the OIII kinematics. However, OIII velocity dispersion is on average larger than stellar velocity dispersion by a factor of 1.3-1.4, suggesting that the non-gravitational component, i.e., outflows, is almost comparable to the gravitational component. Second, the increase of the OIII velocity dispersion (after normalized by stellar velocity dispersion) with both AGN luminosity and Eddington ratio suggests that non-gravitational kinematics are clearly linked to AGN accretion. The distribution in the OIII velocity - velocity dispersion diagram dramatically expands toward large val...

  6. Scientists Explain Catalysis Neutralizing Car's Tail Gas

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ The neutralization of the car's tail gas is a problem of practical importance in the eyes of both experimental and theoretical physicists. Recently, a group of CAS scientists join hands with the Queen's University of Belfast in the UK to make advances in exploring the process of CO oxidation in a bid to reduce the air pollution caused by the car's exhaust gas. The work has been supported by the "National 973Program" and the CAS Foundation for Overseas Studies. On March 4,its result was published by the Internet edition of the Journal of the American Chemical Society.

  7. Four-fluid MHD simulations of the plasma and neutral gas environment of comet 67P/Churyumov-Gerasimenko near perihelion

    Science.gov (United States)

    Huang, Zhenguang; Tóth, Gábor; Gombosi, Tamas I.; Jia, Xianzhe; Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi, Michael R.; Bieler, Andre; Hansen, Kenneth C.; Shou, Yinsi; Altwegg, Kathrin

    2016-05-01

    The neutral and plasma environment is critical in understanding the interaction of the solar wind and comet 67P/Churyumov-Gerasimenko (CG), the target of the European Space Agency's Rosetta mission. To serve this need and support the Rosetta mission, we have developed a 3-D four-fluid model, which is based on BATS-R-US (Block-Adaptive Tree Solarwind Roe-type Upwind Scheme) within SWMF (Space Weather Modeling Framework) that solves the governing multifluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. This model incorporates different mass loading processes, including photoionization and electron impact ionization, charge exchange, dissociative ion-electron recombination, and collisional interactions between different fluids. We simulated the plasma and neutral gas environment near perihelion in three different cases: an idealized comet with a spherical body and uniform neutral gas outflow, an idealized comet with a spherical body and illumination-driven neutral gas outflow, and comet CG with a realistic shape model and illumination-driven neutral gas outflow. We compared the results of the three cases and showed that the simulations with illumination-driven neutral gas outflow have magnetic reconnection, a magnetic pileup region and nucleus directed plasma flow inside the nightside reconnection region, which have not been reported in the literature.

  8. Laboratory simulation of cometary neutral gas ionization

    Science.gov (United States)

    Chang, Tsuey-Fen; Rahman, H. U.; White, R. S.

    1989-01-01

    The laboratory simulation of the interaction of the solar wind with a comet is used to study the cometary neural gas ionization. The experiment is carried out in the UCR T-1 facility with an ice ball as the comet model. Photographs and data are taken with a variety of values of the solar wind velocity, interplanetary magnetic field (IMF), and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above certain minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. The critical magnetic field may be explained by assuming two stream lower hybrid instability as a triggering mechanism for the ionization of the neutral gas by plasma flow. Critical upper and lower limits for the magnetic field, required by anomalous ionization, are also derived that satisfy the experimental observations.

  9. The Production of Cold Gas Within Galaxy Outflows

    Science.gov (United States)

    Scannapieco, Evan

    2017-03-01

    I present a suite of three-dimensional simulations of the evolution of initially hot material ejected by starburst-driven galaxy outflows. The simulations are conducted in a comoving frame that moves with the material, tracking atomic/ionic cooling, Compton cooling, and dust cooling and destruction. Compton cooling is the most efficient of these processes, while the main role of atomic/ionic cooling is to enhance density inhomogeneities. Dust, on the other hand, has little effect on the outflow evolution, and is rapidly destroyed in all the simulations except for the case with the smallest mass flux. I use the results to construct a simple steady-state model of the observed UV/optical emission from each outflow. The velocity profiles in this case are dominated by geometric effects, and the overall luminosities are extremely strong functions of the properties of the host system, as observed in ultra-luminous infrared galaxies (ULIRGs). Furthermore the luminosities and maximum velocities in several models are consistent with emission-line observations of ULIRGs, although the velocities are significantly greater than observed in absorption-line studies. It may be that absorption line observations of galaxy outflows probe entrained cold material at small radii, while emission-line observations probe cold material condensing from the initially hot medium at larger distances.

  10. Galactic outflow and diffuse gas properties at z>=1 using different baryonic feedback models

    CERN Document Server

    Barai, Paramita; Murante, Giuseppe; Ragagnin, Antonio; Viel, Matteo

    2014-01-01

    We measure and quantify properties of galactic outflows and diffuse gas at $z \\geq 1$ in cosmological hydrodynamical simulations. Our novel sub-resolution model, MUPPI, implements supernova feedback using fully local gas properties, where the wind velocity and mass loading are not given as input. We find the following trends at $z = 2$ by analysing central galaxies having a stellar mass higher than $10^{9} M_{\\odot}$. The outflow velocity and mass outflow rate ($\\dot{M}_{\\rm out}$) exhibit positive correlations with galaxy mass and with the star formation rate (SFR). However, most of the relations present a large scatter. The outflow mass loading factor ($\\eta$) is between $0.2 - 10$. The comparison Effective model generates a constant outflow velocity, and a negative correlation of $\\eta$ with halo mass. The number fraction of galaxies where outflow is detected decreases at lower redshifts, but remains more than $80 \\%$ over $z = 1 - 5$. High SF activity at $z \\sim 2 - 4$ drives strong outflows, causing the ...

  11. Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253

    Science.gov (United States)

    Walter, Fabian; Bolatto, Alberto D.; Leroy, Adam K.; Veilleux, Sylvain; Warren, Steven R.; Hodge, Jacqueline; Levy, Rebecca C.; Meier, David S.; Ostriker, Eve C.; Ott, Jürgen; Rosolowsky, Erik; Scoville, Nick; Weiss, Axel; Zschaechner, Laura; Zwaan, Martin

    2017-02-01

    We present a detailed study of a molecular outflow feature in the nearby starburst galaxy NGC 253 using ALMA. We find that this feature is clearly associated with the edge of NGC 253's prominent ionized outflow, has a projected length of ∼300 pc, with a width of ∼50 pc, and a velocity dispersion of ∼40 km s‑1, which is consistent with an ejection from the disk about 1 Myr ago. The kinematics of the molecular gas in this feature can be interpreted (albeit not uniquely) as accelerating at a rate of 1 km s‑1 pc‑1. In this scenario, the gas is approaching an escape velocity at the last measured point. Strikingly, bright tracers of dense molecular gas (HCN, CN, HCO+, CS) are also detected in the molecular outflow: we measure an HCN(1–0)/CO(1–0) line ratio of ∼ 1/10 in the outflow, similar to that in the central starburst region of NGC 253 and other starburst galaxies. By contrast, the HCN/CO line ratio in the NGC 253 disk is significantly lower (∼ 1/30), similar to other nearby galaxy disks. This strongly suggests that the streamer gas originates from the starburst, and that its physical state does not change significantly over timescales of ∼1 Myr during its entrainment in the outflow. Simple calculations indicate that radiation pressure is not the main mechanism for driving the outflow. The presence of such dense material in molecular outflows needs to be accounted for in simulations of galactic outflows.

  12. Neutral gas density depletion due to neutral gas heating and pressure balance in an inductively coupled plasma

    Science.gov (United States)

    Shimada, Masashi; Tynan, George R.; Cattolica, Robert

    2007-02-01

    The spatial distribution of neutral gas temperature and total pressure have been measured for pure N2, He/5%N2 and Ar/5%N2 in an inductively coupled plasma (ICP) reactor, and a significant rise in the neutral gas temperature has been observed. When thermal transpiration is used to correct total pressure measurements, the total pressure remains constant regardless of the plasma condition. Neutral pressure is depleted due to the pressure balance when the plasma pressure (mainly electron pressure) becomes comparable to the neutral pressure in high density plasma. Since the neutral gas follows the ideal gas law, the neutral gas density profile was obtained from the neutral gas temperature and the corrected neutral pressure measurements. The results show that the neutral gas density at the centre of the plasma chamber (factor of 2-4 ×) decreases significantly in the presence of a plasma discharge. Significant spatial variation in neutral gas uniformity occurs in such plasmas due to neutral gas heating and pressure balance.

  13. A molecular survey of outflow gas: velocity-dependent shock chemistry and the peculiar composition of the EHV gas

    Science.gov (United States)

    Tafalla, M.; Santiago-García, J.; Hacar, A.; Bachiller, R.

    2010-11-01

    Context. Bipolar outflows from Class 0 protostars often present two components in their CO spectra that have different kinematic behaviors: a smooth outflow wing and a discrete, extremely high-velocity (EHV) peak. Aims: To better understand the origin of these two outflow components, we have studied and compared their molecular composition. Methods: We carried out a molecular survey of the outflows powered by L1448-mm and IRAS 04166+2706, two sources with prominent wing and EHV components. For each source, we observed a number of molecular lines towards the brightest outflow position and used them to determine column densities for 12 different molecular species. Results: The molecular composition of the two outflows is very similar. It presents systematic changes with velocity that we analyze by dividing the outflow in three chemical regimes, two of them associated with the wing component and the other the EHV gas. The analysis of the two wing regimes shows that species like H2CO and CH3OH favor the low-velocity gas, while SiO and HCN are more abundant in the fastest gas. This fastest wing gas presents strong similarities with the composition of the “chemically active” L1157 outflow (whose abundances we re-evaluate in an appendix). We find that the EHV regime is relatively rich in O-bearing species compared to the wing regime. The EHV gas is not only detected in CO and SiO (already reported elsewhere), but also in SO, CH3OH, and H2CO (newly reported here), with a tentative detection in HCO+. At the same time, the EHV regime is relatively poor in C-bearing molecules like CS and HCN, for which we only obtain weak detections or upper limits despite deep integrations. We suggest that this difference in composition arises from a lower C/O ratio in the EHV gas. Conclusions: The different chemical compositions of the wing and EHV regimes suggest that these two outflow components have different physical origins. The wing component is better explained by shocked ambient

  14. AGN-Enhanced Outflows of Low-Ionization Gas in Star-Forming Galaxies at 1.7

    Science.gov (United States)

    Talia, Margherita; Brusa, Marcella; Cimatti, Andrea; VUDS Team

    2017-07-01

    To reproduce the properties of galaxies in the local Universe, as well as the scaling relations between host galaxies and black holes properties, many galaxy formation models invoke the presence of fast and energetic winds extending over galaxy scales. These massive gas outflows can be powered either by star-formation (SF) or AGN activity, though the relative dominance and efficiency of the different mechanisms is not yet fully understood. In the last decade much effort has been put in the search for observational evidence of such phenomena, especially at the peak of both SF and AGN activity through cosmic time (1evidence of fast material moving towards our line of sight. More recently, especially thanks to new facilities like ALMA, outflows are being observed also in neutral and molecular gas. We collected a large sample of AGNs and SFGs at z>1 from large optical spectroscopic surveys (zCOSMOS, VUDS, ESO public surveys), complemented with HST imaging, X-ray (Chandra) and IR data, and we concentrated our analysis on the ISM absorption lines in the rest-frame UV wavelength range. The analysis of the ISM absorption lines in stacked spectra confirmed that galaxies hosting an AGN show outflows moving at speeds ( 600-800 km/s) much faster than in the case of pure SFGs. However, though the AGN might be responsible of an enhanced gas outflow activity with respect to SF alone, the analysis of the sample also shows that there is no correlation between the power of the AGN, as traced by its X-ray luminosity, and the velocity of the warm phase of the outflow traced by the ISM UV absorption lines. This result is at odds with previous findings reported for the highly ionized phase in local AGN, suggesting that the two phases of the outflow are mixed only in relatively low-velocity outflows.

  15. GAS OUTFLOWS IN SEYFERT GALAXIES: EFFECTS OF STAR FORMATION VERSUS AGN FEEDBACK

    Energy Technology Data Exchange (ETDEWEB)

    Melioli, C.; Pino, E. M. de Gouveia Dal, E-mail: claudio.melioli@iag.usp.br, E-mail: dalpino@iag.usp.br [Department of Astronomy (IAG-USP), University of Sao Paulo (Brazil)

    2015-10-20

    Large-scale, weakly collimated outflows are very common in galaxies with large infrared luminosities. In complex systems in particular, where intense star formation (SF) coexists with an active galactic nucleus (AGN), it is not clear yet from observations whether the SF, the AGN, or both are driving these outflows. Accreting supermassive black holes are expected to influence their host galaxies through kinetic and radiative feedback processes, but in a Seyfert galaxy, where the energy emitted in the nuclear region is comparable to that of the body of the galaxy, it is possible that stellar activity is also playing a key role in these processes. In order to achieve a better understanding of the mechanisms driving the gas evolution especially at the nuclear regions of these galaxies, we have performed high-resolution three-dimensional hydrodynamical simulations with radiative cooling considering the feedback from both SF regions, including supernova (Type I and II) explosions and an AGN jet emerging from the central region of the active spiral galaxy. We computed the gas mass lost by the system, separating the role of each of these injection energy sources on the galaxy evolution, and found that at scales within 1 kpc an outflow can be generally established considering intense nuclear SF only. The jet alone is unable to drive a massive gas outflow, although it can sporadically drag and accelerate clumps of the underlying outflow to very high velocities.

  16. Galaxy evolution in cosmological simulations with outflows - II. Metallicities and gas fractions

    Science.gov (United States)

    Davé, Romeel; Finlator, Kristian; Oppenheimer, Benjamin D.

    2011-09-01

    We use cosmological hydrodynamic simulations to investigate how inflows, star formation and outflows govern the gaseous and metal content of galaxies within a hierarchical structure formation context. In our simulations, galaxy metallicities are established by a balance between inflows and outflows as governed by the mass outflow rate, implying that the mass-metallicity relation reflects how the outflow rate varies with stellar mass. Gas content, meanwhile, is set by a competition between inflow into and gas consumption within the interstellar medium, the latter being governed by the star formation law, while the former is impacted by both wind recycling and preventive feedback. Stochastic variations in the inflow rate move galaxies off the equilibrium mass-metallicity and mass-gas fraction relations in a manner correlated with the star formation rate, and the scatter is set by the time-scale to re-equilibrate. The evolution of both relations from z= 3 → 0 is slow, as individual galaxies tend to evolve mostly along the relations. Gas fractions at a given stellar mass slowly decrease with time because the cosmic inflow rate diminishes faster than the consumption rate, while metallicities slowly increase as infalling gas becomes more enriched. Observations from z˜ 3 → 0 are better matched by simulations employing momentum-driven wind scalings rather than constant wind speeds, but all models predict too low gas fractions at low masses and too high metallicities at high masses. All our models reproduce observed second-parameter trends of the mass-metallicity relation with the star formation rate and environment, indicating that these are a consequence of equilibrium and not feedback. Overall, the analytical framework of our equilibrium scenario broadly captures the relevant physics establishing the galaxy gas and metal content in simulations, which suggests that the cycle of baryonic inflows and outflows centrally governs the cosmic evolution of these properties

  17. Investigations of Protostellar Outflow Launching and Gas Entrainment: Hydrodynamic Simulations and Molecular Emission

    CERN Document Server

    Offner, S S R

    2013-01-01

    We investigate protostellar outflow evolution, gas entrainment, and star formation efficiency using radiation-hydrodynamic simulations of isolated, turbulent low-mass cores. We adopt an X-wind launching model, in which the outflow rate is coupled to the instantaneous protostellar accretion rate and evolution. We vary the outflow collimation angle from $\\theta$=0.01-0.1 and find that even well collimated outflows effectively sweep up and entrain significant core mass. The Stage 0 lifetime ranges from 0.14-0.19 Myr, which is similar to the observed Class 0 lifetime. The star formation efficiency of the cores spans 0.41-0.51. In all cases, the outflows drive strong turbulence in the surrounding material. Although the initial core turbulence is purely solenoidal by construction, the simulations converge to approximate equipartition between solenoidal and compressive motions due to a combination of outflow driving and collapse. When compared to a simulation of a cluster of protostars, which is not gravitationally ...

  18. Galaxy Evolution in Cosmological Simulations with Outflows II: Metallicities and Gas Fractions

    CERN Document Server

    Davé, Romeel; Oppenheimer, Benjamin D

    2011-01-01

    We use cosmological hydrodynamic simulations to investigate how inflows, star formation, and outflows govern the the gaseous and metal content of galaxies. In our simulations, galaxy metallicities are established by a balance between inflows and outflows as governed by the mass outflow rate, implying that the mass-metallicity relation reflects how the outflow rate varies with stellar mass. Gas content is set by a competition between inflow into and gas consumption within the ISM, the latter being governed by the star formation law, while the former is impacted by both wind recycling and preventive feedback. Stochasticity in the inflow rate moves galaxies off the equilibrium mass-metallicity and mass-gas fraction relations in a manner correlated with the SFR, and the scatter is set by the timescale to re-equilibrate. The evolution of both relations from z=3-0 is slow, as individual galaxies tend to evolve mostly along the relations. Gas fractions at a given stellar mass slowly decrease with time because the co...

  19. The response of relativistic outflowing gas to the inner accretion disk of a black hole.

    Science.gov (United States)

    Parker, Michael L; Pinto, Ciro; Fabian, Andrew C; Lohfink, Anne; Buisson, Douglas J K; Alston, William N; Kara, Erin; Cackett, Edward M; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C; Garcia, Javier; Harrison, Fiona A; King, Ashley L; Middleton, Matthew J; Miller, Jon M; Miniutti, Giovanni; Reynolds, Christopher S; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J; Wilkins, Daniel R; Zoghbi, Abderahmen

    2017-03-01

    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different

  20. The response of relativistic outflowing gas to the inner accretion disk of a black hole

    Science.gov (United States)

    Parker, Michael L.; Pinto, Ciro; Fabian, Andrew C.; Lohfink, Anne; Buisson, Douglas J. K.; Alston, William N.; Kara, Erin; Cackett, Edward M.; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C.; Garcia, Javier; Harrison, Fiona A.; King, Ashley L.; Middleton, Matthew J.; Miller, Jon M.; Miniutti, Giovanni; Reynolds, Christopher S.; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J.; Wilkins, Daniel R.; Zoghbi, Abderahmen

    2017-03-01

    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these—the ultrafast outflows—are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224‑3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very

  1. Outflowing atomic and molecular gas at z ~ 0.67 towards 1504 + 377

    Science.gov (United States)

    Kanekar, Nissim; Chengalur, Jayaram N.

    2008-02-01

    We report the detection of OH 1667-MHz and wide HI 21-cm absorption at z ~ 0.67 towards the red quasar 1504 + 377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21-cm absorption extends over a velocity range of ~600kms-1 blueward of the quasar redshift (z = 0.674), with the new OH 1667-MHz absorption component at ~-430kms-1, nearly coincident with earlier detections of millimetre-wave absorption at z ~ 0.6715. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate and a molecular hydrogen fraction . The radio structure of 1504 + 377 is consistent with the outflow arising as a result of a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO+ and OH column densities is ~20 times higher than typical values in Galactic and high-z absorbers. This could arise because of small-scale structure in the outflowing gas on sub-parsec scales, which would also explain the observed variability in the HI 21-cm line.

  2. Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA

    Science.gov (United States)

    Salak, Dragan; Nakai, Naomasa; Hatakeyama, Takuya; Miyamoto, Yusuke

    2016-05-01

    NGC 1808 is a nearby barred starburst galaxy with an outflow from the nuclear region. To study the inflow and outflow processes related to star formation and dynamical evolution of the galaxy, we have carried out 12CO (J=1-0) mapping observations of the central r ˜ 4 kpc of NGC 1808 using the Atacama Large Millimeter/submillimeter Array. Four distinct components of molecular gas are revealed at high spatial resolution of 2″ (˜100 pc): (1) a compact (r CND), (2) r ˜ 500 pc ring, (3) gas-rich galactic bar, and (4) spiral arms. Basic geometric and kinematic parameters are derived for the central 1 kpc region using tilted-ring modeling. The derived rotation curve reveals multiple mass components that include (1) a stellar bulge, (2) a nuclear bar and molecular CND, and (3) an unresolved massive (˜107 M ⊙) core. Two systemic velocities, 998 km s-1 for the CND and 964 km s-1 for the 500 pc ring, are revealed, indicating a kinematic offset. The pattern speed of the primary bar, derived by using a cloud-orbit model, is 56 ± 11 km s-1 kpc-1. Noncircular motions are detected associated with a nuclear spiral pattern and outflow in the central 1 kpc region. The ratio of the mass outflow rate to the star formation rate is {\\dot{M}}{out}/{SFR}˜ 0.2 in the case of optically thin CO (1-0) emission in the outflow, suggesting low efficiency of star formation quenching.

  3. Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies

    Science.gov (United States)

    Arribas, S.; Colina, L.; Bellocchi, E.; Maiolino, R.; Villar-Martín, M.

    2014-08-01

    We study the kinematic properties of the ionised gas outflows and ambient interstellar medium (ISM) in a large and representative sample of local luminous and ultra-luminous infrared galaxies (U/LIRGs) (58 systems, 75 galaxies) at galactic and sub-galactic (i.e., star-forming clumps) scales, thanks to integral field spectroscopy (IFS)-based high signal-to-noise integrated spectra. The velocity dispersion of the ionized ISM in U/LIRGs (⟨ σ ⟩ ~ 70 km s-1) is larger than in lower luminosity local star-forming galaxies (⟨ σ ⟩ ~ 25 km s-1). While for isolated disc LIRGs star formation appears to sustain turbulence, gravitational energy release associated with interactions and mergers plays an important role in driving σ in the U/LIRG range. We find that σ has a dependency on the star formation rate density (ΣSFR), which is weaker than expected if it were driven by the energy released by the starburst. The relatively small role of star formation (SF) driving the σ in U/LIRGs is reinforced by the lack of an increase in σ associated with high luminosity SF clumps. We also find that the impact of an active galactic nucleus (AGN) in ULIRGs is strong, increasing on average σ by a factor 1.5. Low-z U/LIRGs cover a range of velocity dispersion (σ ~ 30 to 100 km s-1) and star formation rate density (ΣSFR ~ 0.1 to 20 M⊙ yr-1 kpc-2) similar to those of high-z SFGs. Moreover, the observed weak dependency of σ on ΣSFR for local U/LIRGs (σ ∝ ΣSFR+0.06) is in very good agreement with that measured in some high-z samples. The presence of ionized gas outflows in U/LIRGs seems universal based on the detection of a broad, usually blueshifted, Hα line. The observed dependency of the maximum velocity of the outflow (Vmax) on the star formation rate (SFR) is of the type Vmax(non - AGN) ∝ SFR(LIR)+ 0.24. We find that AGNs in U/LIRGs are able to generate faster (~×2) and more massive (~× 1.4) ionized gas outflows than pure starbursts. The derived ionized mass

  4. Modeling of neutral gas dynamics in high-density plasmas

    Science.gov (United States)

    Canupp, Patrick Wellington

    This thesis describes a physical model of chemically reactive neutral gas flow and discusses numerical solutions of this model for the flow in an inductively coupled plasma etch reactor. To obtain these solutions, this research develops an efficient, implicit numerical method. As a result of the enhanced numerical stability of the scheme, large time steps advance the solution from initial conditions to a final steady state in fewer iterations and with less computational expense than simpler explicit methods. This method would incorporate suitably as a module in currently existing large scale plasma simulation tools. In order to demonstrate the accuracy of the numerical technique, this thesis presents results from two simulations of flows that possess theoretical solutions. The first case is the inviscid flow of a gas through a converging nozzle. A comparison of the numerical solution to isentropic flow theory shows that the numerical technique capably captures the essential flow features of this environment. The second case is the Couette flow of a gas between two parallel plates. The simulation results compare well with the exact solution for this flow. After establishing the accuracy of the numerical technique, this thesis discusses results for the flow of chemically reactive gases in a chlorine plasma etch reactor. This research examines the influence of the plasma on the neutral gas and the dynamics exhibited by the neutral gas in the reactor. This research finds that the neutral gas temperature strongly depends on the rate at which inelastic, electron-impact dissociation reactions occur and on atomic chlorine wall recombination rates. Additionally, the neutral gas Aow in the reactor includes a significant mass flux of etch product from the wafer surface. Resolution of these effects is useful for neutral gas simulation. Finally, this thesis demonstrates that continuum fluid models provide reasonable accuracy for these low pressure reactor flows due to the fact

  5. Long way to go: how outflows from large galaxies propagate through the hot halo gas

    CERN Document Server

    Sarkar, Kartick Chandra; Sharma, Prateek; Shchekinov, Yuri

    2014-01-01

    Abridged Abstract: Using hydrodynamic simulations, we study the mass loss rate due to supernova-driven outflows from Milky Way type disk galaxies. Our goal is to relate the wind mass loss rates at different radii and times, and the central star formation rate (SFR). In particular, we study the role of the often-neglected extended halo gas. We find that the time averaged mass loss rate at inner radii scales roughly linearly with the star formation rate ($\\dot{M} \\propto {\\rm SFR}^{0.75}$), and that the mass loading factor at the virial radius is roughly half its value at the inner radii. The temperature distribution of the outflowing material in the very inner region ($\\sim $10 kpc) is found to be bimodal in nature , peaking at $10^5$ K and $10^{6.5}$ K, responsible for optical and X-ray emission, respectively. The contribution of cold/warm gas with temperature $\\le 10^{5.5}$ K to the outflow rate within 10 kpc is $\\approx 0.3\\hbox{--}0.5$. This helps us to connect the warm mass loading factor ($\\eta_{3e5}$, e...

  6. Gas outflows in Seyfert galaxies: effects of star formation versus AGN feedbacks

    CERN Document Server

    Melioli, Claudio

    2015-01-01

    Large scale, weakly collimated outflows are very common in galaxies with large infrared luminosities. In complex systems in particular, where intense star formation (SF) coexists with an active galactic nucleus (AGN), it is not clear yet from observations whether the SF, the AGN, or both are driving these outflows. Accreting supermassive black holes (SMBHs) are expected to influence their host galaxies through kinetic and radiative feedback processes, but in a Seyfert galaxy where the energy emitted in the nuclear region is comparable to that of the body of the galaxy, it is possible that stellar activity is also playing a key role in these processes. In order to achieve a better understanding of the mechanisms driving the gas evolution specially at the nuclear regions of these galaxies, we have performed high-resolution three-dimensional hydrodynamical simulations with radiative cooling considering the feedback from both star formation regions including supernova (type I and II) explosions and an AGN jet eme...

  7. Tracing the neutral gas environments of young radio AGN with ASKAP

    CERN Document Server

    Allison, J R; Moss, V A; Harvey-Smith, L; Heywood, I; Indermuehle, B T; McConnell, D; Sault, R J; Whiting, M T

    2015-01-01

    At present neutral atomic hydrogen (HI) gas in galaxies at redshifts above $z \\sim 0.3$ (the extent of 21-cm emission surveys in individual galaxies) and below $z \\sim 1.7$ (where the Lyman-$\\alpha$ line is not observable with ground-based telescopes) has remained largely unexplored. The advent of precursor telescopes to the Square Kilometre Array will allow us to conduct the first systematic radio-selected 21-cm absorption surveys for HI over these redshifts. While HI absorption is a tracer of the reservoir of cold neutral gas in galaxies available for star formation, it can also be used to reveal the extreme kinematics associated with jet-driven neutral outflows in radio-loud active galactic nuclei. Using the six-antenna Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder, we have demonstrated that in a single frequency tuning we can detect HI absorption over a broad range of redshifts between $z = 0.4$ and $1.0$. As part of our early science and commissioning program, we are...

  8. High-velocity gas toward hot molecular cores: evidence for collimated outflows from embedded sources

    CERN Document Server

    Gibb, A G; Wyrowski, F

    2004-01-01

    We present observations made with the Berkeley-Illinois-Maryland Association millimeter array of the H2S 2(2,0)-2(1,1) and C18O 2-1 transitions toward a sample of four hot molecular cores associated with ultracompact HII regions: G9.62+0.19, G10.47+0.03, G29.96-0.02 and G31.41+0.31. The angular resolution varies from 1.5 to 2.4 arcsec, corresponding to scales of ~0.06 pc at the distance of these sources. High-velocity wings characteristic of molecular outflows are detected toward all four sources in the H2S line. In two cases (G29.96 and G31.41) red- and blueshifted lobes are clearly defined and spatially separate, indicating that the flows are collimated. We also confirm the previous detection of the outflow in G9.62F. Although the gas-phase H2S abundance is not well constrained, assuming a value of 10^-7 yields lower limits to total outflow masses of ~8 Msun, values which are consistent with the driving sources being massive protostars. Linear velocity gradients are detected in both C18O and H2S across G9.6...

  9. Outflowing atomic and molecular gas at $z \\sim 0.67$ towards 1504+377

    CERN Document Server

    Kanekar, Nissim

    2007-01-01

    We report the detection of OH 1667 MHz and wide HI 21cm absorption at $z \\sim 0.67$ towards the red quasar 1504+377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21cm absorption extends over a velocity range of $\\sim 600$ km/s blueward of the quasar redshift ($z=0.674$), with the new OH 1667 MHz absorption component at $\\sim -430$ \\kms, nearly coincident with earlier detections of mm-wave absorption at $z \\sim 0.6715$. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate ${\\dot M} \\sim 12 M_\\odot$ yr$^{-1}$ and a molecular hydrogen fraction $f_{\\rm H_2} \\equiv (N_{\\rm H_2}/N_{\\rm HI}) \\sim 0.2$. The radio structure of 1504+377 is consistent with the outflow arising due to a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO$^+$ to OH column densities is $\\sim 20$ times higher than typical values in Galactic and high-$z$ absorbers. This could arise due to small-scale ...

  10. NIHAO VIII: Circum-galactic medium and outflows - The puzzles of HI and OVI gas distributions

    Science.gov (United States)

    Gutcke, Thales A.; Stinson, Greg S.; Macciò, Andrea V.; Wang, Liang; Dutton, Aaron A.

    2016-10-01

    We study the hot and cold circum-galactic medium (CGM) of 86 galaxies of the cosmological, hydrodynamical simulation suite NIHAO. NIHAO allows a study of how the z = 0 CGM varies across 5 orders of magnitude of stellar mass using OVI and HI as proxies for hot and cold gas. The cool HI covering fraction and column density profiles match observations well, particularly in the inner CGM. OVI shows increasing column densities with mass, a trend seemingly echoed in the observations. As in multiple previous simulations, the OVI column densities in simulations are lower than observed and optically thick HI does not extend as far out as in observations. We take a look at the collisional ionisation fraction of OVI as a function of halo mass. We make observable predictions of the bipolarity of outflows and their effect on the general shape of the CGM. Bipolar outflows can be seen out to around 40 kpc in intermediate and low mass halos (MHalo < 1011 M⊙), but outside that radius, the CGM is too well mixed to detect an elongated shape. Larger halos have extended gas discs beyond the stellar disc that dominate the shape of the inner CGM. The simulated CGM is remarkably spherical even in low mass simulations. The chemical enrichment of both halo and disc gas follow expected increasing trends as a function of halo mass that are well fit with power laws. These relations can be used in non-hydrodynamic models, such as semi-analytic models.

  11. The neutral gas content of post-merger galaxies

    CERN Document Server

    Ellison, Sara L; Rosenberg, Jessica L; Nair, Preethi; Simard, Luc; Torrey, Paul; Patton, David R

    2015-01-01

    Measurements of the neutral hydrogen gas content of a sample of 93 post-merger galaxies are presented, from a combination of matches to the ALFALFA.40 data release and new Arecibo observations. By imposing completeness thresholds identical to that of the ALFALFA survey, and by compiling a mass-, redshift- and environment-matched control sample from the public ALFALFA.40 data release, we calculate gas fraction offsets (Delta f_gas) for the post-mergers, relative to the control sample. We find that the post-mergers have HI gas fractions that are consistent with undisturbed galaxies. However, due to the relative gas richness of the ALFALFA.40 sample, from which we draw our control sample, our measurements of gas fraction enhancements are likely to be conservative lower limits. Combined with comparable gas fraction measurements by Fertig et al. in a sample of galaxy pairs, who also determine gas fraction offsets consistent with zero, we conclude that there is no evidence for significant neutral gas consumption th...

  12. Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA

    CERN Document Server

    Salak, Dragan; Hatakeyama, Takuya; Miyamoto, Yusuke

    2016-01-01

    NGC 1808 is a nearby barred starburst galaxy with an outflow from the nuclear region. To study the inflow and outflow processes related to star formation and dynamical evolution of the galaxy, we have carried out \\(^{12}\\)CO (\\(J=1-0\\)) mapping observations of the central \\(r\\sim4\\) kpc of NGC 1808 using the Atacama Large Millimeter/submillimeter Array (ALMA). Four distinct components of molecular gas are revealed at high spatial resolution of 2\\arcsec (\\(\\sim100\\) pc): (1) a compact (\\(r<200\\) pc) circumnuclear disk (CND), (2) \\(r\\sim500\\) pc ring, (3) gas-rich galactic bar, and (4) spiral arms. Basic geometric and kinematic parameters are derived for the central 1-kpc region using tilted-ring modeling. The derived rotation curve reveals multiple mass components that include (1) a stellar bulge, (2) nuclear bar and molecular CND, and (3) unresolved massive (\\(\\sim10^7~M_\\sun\\)) core. Two systemic velocities, 998 km s\\(^{-1}\\) for the CND and 964 km s\\(^{-1}\\) for the 500-pc ring, are revealed, indicating ...

  13. A new technique to measure the neutralizer cell gas line density applied to a DIII-D neutral beamline

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, D.N.; Hong, R.M.; Riggs, S.P.

    1995-10-01

    The DIII-D tokamak employs eight ion sources for plasma heating. In order to obtain the maximum neutralization of energetic ions (providing maximum neutral beam power) and reduce the heat load on beamline internal components caused by residual energetic ions, sufficient neutral gas must be injected into the beamline neutralizer cell. The neutral gas flow rate must be optimized, however, since excessive gas will increase power losses due to neutral beam scattering and reionization. It is important, therefore, to be able to determine the neutralizer cell gas line density. A new technique which uses the ion source suppressor grid current to obtain the neutralizer cell gas line density has been developed. The technique uses the fact that slow ions produced by beam-gas interactions in the neutralizer cell during beam extraction are attracted to the negative potential applied to the suppressor grid, inducing current flow in the grid. By removing the dependence on beam energy and beam current a normalized suppressor grid current function can be formed which is dependent only on the gas line density. With this technique it is possible to infer the gas line density on a shot by shot basis.

  14. Observational Constraints on a Pluto Torus of Circumsolar Neutral Gas

    Science.gov (United States)

    Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Smith, H. T.; Bagenal, F.; Brown, L. E.; Elliott, H. A.; Haggerty, D. K.; Horanyi, M.; Krimigis, S. M.; Kusterer, M. B.; Lisse, C. M.; McComas, D. J.; Piquette, M. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Vandegriff, J. D.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, S. A.

    2015-12-01

    We present the concept of a neutral gas torus surrounding the Sun, aligned with Pluto's orbit, and place observational constraints based primarily on comparison of New Horizons (NH) measurements with a 3-D Monte Carlo model adapted from analogous satellite tori surrounding Saturn and Jupiter. Such a torus, or perhaps partial torus, should result from neutral N2 escaping from Pluto's exosphere. Unlike other more massive planets closer to the Sun, neutrals escape Pluto readily owing, e.g., to the high thermal speed relative to the escape velocity. Importantly, escaped neutrals have a long lifetime due to the great distance from the Sun, ~100 years for photoionization of N2 and ~180 years for photoionization of N, which results from disassociated N2. Despite the lengthy 248-year orbit, these long e-folding lifetimes may allow an enhanced neutral population to form an extended gas cloud that modifies the N2 spatial profile near Pluto. These neutrals are not directly observable by NH but once ionized N2+ or N+ are picked up by the solar wind, reaching ~50 keV, making these pickup ions (PUIs) detectable by NH's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. PEPSSI observations analyzed to date may constrain the N2 density; the remaining ~95% of the encounter data, scheduled for downlink in August along with similarly anticipated data from the Solar Wind Around Pluto (SWAP) experiment, should help determine the Pluto outgassing rates. Measurements from SWAP include the solar wind speed, a quantity that greatly enhances PUI studies by enabling us to directly account for the PUI distribution's sensitive dependence on plasma speed. Note that anomalous cosmic ray Si observed at Voyager is overabundant by a factor of ~3000 relative to interstellar composition. This might be related to "outer source" PUIs, but the fact that N2 and Si are indistinguishable in many instruments could mean that N2 is actually driving this apparent Si discrepancy.

  15. No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

    CERN Document Server

    Park, J -H; Krichbaum, T P; Kim, J -Y; Kino, M; Bertarini, A; Bremer, M; de Vicente, P

    2015-01-01

    The gas cloud G2 falling toward Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is supposed to provide valuable information on the physics of accretion flows and the environment of the black hole. We observed Sgr A* with four European stations of the Global Millimeter Very Long Baseline Interferometry Array (GMVA) at 86 GHz on 1 October 2013 when parts of G2 had already passed the pericenter. We searched for possible transient asymmetric structure -- such as jets or winds from hot accretion flows -- around Sgr A* caused by accretion of material from G2. The interferometric closure phases remained zero within errors during the observation time. We thus conclude that Sgr A* did not show significant asymmetric (in the observer frame) outflows in late 2013. Using simulations, we constrain the size of the outflows that we could have missed to ~2.5 mas along the major axis, ~0.4 mas along the minor axis of the beam, corresponding to approximately 232 and 35 Schwarzschild radii, ...

  16. Gas physical conditions and kinematics of the giant outflow Ou4

    CERN Document Server

    Corradi, Romano L M; Acker, Agnès; Greimel, Robert; Guillout, Patrick

    2014-01-01

    Ou4 is a recently discovered bipolar outflow with a projected size of more than one degree in the plane of the sky. It is apparently centred on the young stellar cluster -whose most massive representative is the triple system HR8119- inside the HII region Sh 2-129. The driving source, the nature, and the distance of Ou4 are not known. Deep narrow-band imagery of the whole nebula at arcsec resolution was obtained to study its morphology. Long-slit spectroscopy of the tips of the bipolar lobes was secured to determine the gas ionization mechanism, physical conditions, and line-of-sight velocities. An estimate of the proper motions at the tip of the south lobe using archival images is attempted. The existing multi-wavelength data for Sh 2-129 and HR 8119 are also comprehensively reviewed. The morphology of Ou4, its emission-line spatial distribution, line flux ratios, and the kinematic modelling adopting a bow-shock parabolic geometry, illustrate the expansion of a shock-excited fast collimated outflow. The radi...

  17. Outflowing Diffuse Gas in the Active Galactic Nucleus of NGC 1068

    CERN Document Server

    Geballe, T R; Oka, T

    2015-01-01

    Spectra of the archetypal Type II Seyfert galaxy NGC 1068 in a narrow wavelength interval near 3.7 microns have revealed a weak absorption feature due to two lines of the molecular ion H3+. The observed wavelength of the feature corresponds to velocity of -70 km/s relative to the systemic velocity of the galaxy, implying an outward flow from the nucleus along the line of sight. The absorption by H3+ along with the previously known broad hydrocarbon absorption at 3.4~microns probably are formed in diffuse gas that is in close proximity to the continuum source, i.e. within a few tens of parsecs of the central engine. Based on that conclusion and the measured H3+ absorption velocity and with the assumption of a spherically symmetric wind we estimate a rate of mass outflow from the AGN of ~1 Msun/yr.

  18. Reasons For The Experimental Research Of Gas Outflows Based On The Signals Of Weak Interactions Between The Tested Model Of The Gas Pipeline, And Tested Equalizer

    Directory of Open Access Journals (Sweden)

    Rafał Grądzki

    2015-09-01

    Full Text Available This article applies diagnosing issues outflows of gas pipelines using specialized research equipment - equalizers. Variant with only two measuring devices (equalizers, arranged on the inlet and outlet of the pipeline, and the standard pressure transducers and flow rate were considered. The signals from the system and research equipment (equalizers are the basis for the development of new method to test outflow of gas pipeline, which is based on the quotient of the power spectral density of signals generated by the equalizer (diagnoser and signals measured using standard pressure transducers and flow rate. Possible use to analysis the signals power will allow go from signal diagnostic for more effective parametric diagnostic.

  19. Evidence for feedback in action from the molecular gas content in the z ~ 1.6 outflowing QSO XID2028

    Science.gov (United States)

    Brusa, M.; Feruglio, C.; Cresci, G.; Mainieri, V.; Sargent, M. T.; Perna, M.; Santini, P.; Vito, F.; Marconi, A.; Merloni, A.; Lutz, D.; Piconcelli, E.; Lanzuisi, G.; Maiolino, R.; Rosario, D.; Daddi, E.; Bongiorno, A.; Fiore, F.; Lusso, E.

    2015-06-01

    Aims: Gas outflows are believed to play a pivotal role in shaping galaxies, as they regulate both star formation and black hole growth. Despite their ubiquitous presence, the origin and the acceleration mechanism of these powerful and extended winds is not yet understood. Direct observations of the cold gas component in objects with detected outflows at other wavelengths are needed to assess the impact of the outflow on the host galaxy interstellar medium (ISM). Methods: We observed with the Plateau de Bure Interferometer an obscured quasar at z ~ 1.5, XID2028, for which the presence of an ionized outflow has been unambiguously signalled by NIR spectroscopy. The detection of 12CO(3-2) emission in this source allows us to infer the molecular gas content and compare it to the ISM mass derived from the dust emission. We then analyzed the results in the context of recent insights on scaling relations, which describe the gas content of the overall population of star-forming galaxies at a similar redshifts. Results: The star formation efficiency (~100) and gas mass (Mgas = 2.1-9.5 × 1010 M⊙) inferred from the CO(3-2) line depend on the underlying assumptions on the excitation of the transition and the CO-to-H2 conversion factor. However, the combination of this information and the ISM mass estimated from the dust mass suggests that the ISM/gas content of XID2028 is significantly lower than expected for its observed M⋆, sSFR and redshift, based on the most up-to-date calibrations (with gas fraction France), MPG (Germany) and IGN (Spain).A FITS file for the spectrum shown in Fig. 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A11

  20. Experimental and numerical studies of neutral gas depletion in an inductively coupled plasma

    Science.gov (United States)

    Shimada, Masashi

    The central theme of this dissertation is to explore the impact of neutral depletion and coupling between plasma and neutral gas in weakly ionized unmagnetized plasma. Since there have been few systematic studies of the mechanism which leads to non-uniform neutral distribution in processing plasmas, this work investigated the spatial profiles of neutral temperature and pressure experimentally, and the mechanism of resulting neutral depletion by simulation. The experimental work is comprised of neutral temperature measurements using high resolution atomic spectroscopy and molecular spectroscopy, and neutral pressure measurements considering thermal transpiration. When thermal transpiration effects are used to correct the gas pressure measurements, the total pressure remains constant regardless of the plasma condition. Since the neutral gas follows the ideal gas law, the neutral gas density profile is also obtained from the measured neutral gas temperature and the corrected pressure measurements. The results show that neutral gas temperature rises close to ˜ 900 [K], and the neutral gas density at the center of plasma chamber has a significant (factor of 2-4x) decrease in the presence of a plasma discharge. In numerical work, neutral and ion transport phenomena were simulated by a hybrid-type direct simulation Monte Carlo (DSMC) method of one dimensional (1D) electrostatic plasma to identify the mechanism of the neutral gas density depletion in Ar/N2 mixtures. The simulation reveals that the neutral depletion is the result of the interplay between plasma and neutral gas, and a parametric study indicates that neutral depletion occurs mainly due to gas heating and pressure balance for the typical condition of plasma processing. In high density plasma sources (Te ≈ 2-5 eV, ne ≈ 1011-1012 cm-3) where the plasma pressure becomes comparable to neutral pressure, total pressure (neutral pressure and plasma pressure) is conserved before and after the discharge. Therefore

  1. Gas physical conditions and kinematics of the giant outflow Ou4

    Science.gov (United States)

    Corradi, Romano L. M.; Grosso, Nicolas; Acker, Agnès; Greimel, Robert; Guillout, Patrick

    2014-10-01

    Context. The recently discovered bipolar outflow Ou4 has a projected size of more than one degree in the plane of the sky. It is apparently centred on the young stellar cluster - whose most massive representative is the triple system HR 8119 - inside the H ii region Sh 2-129. The driving source, the nature, and the distance of Ou4 are not known. Aims: The basic properties of Ou4 and its environment are investigated to shed light on the origin of this remarkable outflow. Methods: Deep narrow-band imagery of the whole nebula at arcsecond resolution was obtained to study the details of its morphology. Long-slit spectroscopy of the bipolar lobe tips was secured to determine the gas ionisation mechanism, physical conditions, and line-of-sight velocities. An estimate of the proper motions at the tip of the south lobe using archival plate images was attempted. The existing multi-wavelength data for Sh 2-129 and HR 8119 were also comprehensively reviewed. Results: The observed morphology of Ou4, its emission-line spatial distribution, line flux ratios, and the kinematic modelling developed adopting a bow-shock parabolic geometry, illustrate the expansion of a shock-excited fast collimated outflow. The observed radial velocities of Ou4 and its reddening are consistent with those of Sh 2-129 and HR 8119. The improved determination of the distance to HR 8119 (composed of two B0 V and one B0.5 V stars) and Sh 2-129 is 712 pc. We identify in WISE images at 22 μm an emission bubble of 5' radius (1 pc at the distance above) emitted by hot (107 K) dust grains, located inside the central part of Ou4 and corresponding to several [O iii] emission features of Ou4. Conclusions: The apparent position of Ou4 and the properties studied in this work are consistent with the hypothesis that Ou4 is located inside the Sh 2-129 H ii region, suggesting that it was launched some 90 000 yr ago by HR 8119. The outflow total kinetic energy is estimated to be ≈4 × 1047 ergs. However, we cannot

  2. A Ten Billion Solar Mass Outflow of Molecular Gas Launched by Radio Bubbles in the Abell 1835 Brightest Cluster Galaxy

    CERN Document Server

    McNamara, B R; Nulsen, P E J; Edge, A C; Murray, N W; Main, R A; Vantyghem, A N; Combes, F; Fabian, A C; Salome, P; Kirkpatrick, C C; Baum, S A; Bregman, J N; Donahue, M; Egami, E; Hamer, S; O'Dea, C P; Oonk, J B R; Tremblay, G; Voit, G M

    2013-01-01

    We report ALMA Early Science observations of the Abell 1835 brightest cluster galaxy (BCG) in the CO (3-2) and CO (1-0) emission lines. We detect 5E10 solar masses of molecular gas within 10 kpc of the BCG. Its velocity width of ~130 km/s FWHM is too narrow to be supported by dynamical pressure. The gas may instead be supported in a rotating, turbulent disk oriented nearly face-on. The disk is forming stars at a rate of 100-180 solar masses per year. Roughly 1E10 solar masses of molecular gas is projected 3-10 kpc to the north-west and to the east of the nucleus with line of sight velocities lying between -250 km/s to +480 km/s with respect to the systemic velocity. Although inflow cannot be ruled out, the rising velocity gradient with radius is consistent with a broad, bipolar outflow driven by radio jets or buoyantly rising X-ray cavities. The molecular outflow may be associated with an outflow of hot gas in Abell 1835 seen on larger scales. Molecular gas is flowing out of the BCG at a rate of approximately...

  3. The Complex Neutral Gas Dynamics Of The Dwarf Starburst Galaxy NGC 625

    CERN Document Server

    Cannon, J M; Skillman, E D; Côté, S; Cannon, John M.; Skillman, Evan D.; Cote, Stephanie

    2004-01-01

    We present new multi-configuration HI aperture synthesis imaging of the nearby dwarf starburst galaxy NGC 625 obtained with the Australia Telescope Compact Array. Total HI column density images show gas well-aligned with the optical major axis, and low-column density HI extending to > 6 optical scale lengths. The HI velocity field, on the other hand, is highly disturbed, with neutral gas at nearly all detected velocities within the central region. After considering various interpretations, we find that a blowout scenario most accurately describes the data. Since at our resolution we do not detect any large evacuated holes in the HI disk, we interpret this blowout to be the result of the extended (both spatially and temporally) star formation event which NGC 625 has undergone in the last 100 Myr. This is one of the clearest examples of HI outflow detected in a dwarf galaxy. We find no obvious external trigger for this extended star formation event. We detect strong radio continuum emission from the largest HII...

  4. Germany 2050 a greenhouse gas-neutral country. Background paper

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Kathrin; Nissler, Diana (eds.)

    2013-10-15

    For several years, the German Federal Environment Agency (UBA) has been looking at the question how the climate target of a GHG-neutral Germany can be achieved. In a multi-disciplinary project launched by the agency, the first point of call was power generation because of its high emissions. It was shown in 2010 that power generation from 100 % renewable energy is possible. Even then it was understood that a renewable energy supply alone would not be enough to completely abolish greenhouse gas emissions. Other sectors of the economy would have to follow suit and undergo major changes, relying on low-GHG technology. Consequently, the study now submitted, ''Greenhouse gas-neutral Germany 2050'', includes in its research all relevant emission sources that are described in the annual National Inventory Report (NIR) on emissions and removal of greenhouse gases. Alongside complete energy supply, including heating and transport, we also look at emissions from industry, waste disposal, agriculture and forestry as well as changes in land use. We develop a target scenario. The transformations that lead to the target and related economic considerations or the selection of appropriate policy instruments, however, are not part of our study. The scenario analysis is based on the assumption that in 2050, Germany will still be an exporting industrial country with an average annual growth of 0.7 % of its gross domestic product.

  5. The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift

    Energy Technology Data Exchange (ETDEWEB)

    Bournaud, Frédéric; Renaud, Florent; Daddi, Emanuele; Duc, Pierre-Alain; Elbaz, David; Gabor, Jared M.; Juneau, Stéphanie; Kraljic, Katarina; Le Floch' , Emeric [CEA, IRFU/SAp, F-91191 Gif-Sur-Yvette (France); Perret, Valentin; Amram, Philippe; Epinat, Benoit [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille), F-13388 Marseille (France); Dekel, Avishai [Center for Astrophysics and Planetary Science, Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Elmegreen, Bruce G. [IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598 (United States); Elmegreen, Debra M. [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States); Teyssier, Romain [Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich (Switzerland)

    2014-01-01

    Star-forming disk galaxies at high redshift are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood. The main question is whether the clumps disrupt within their dynamical timescale (≤50 Myr), like the molecular clouds in today's galaxies, or whether they survive stellar feedback for more than a disk orbital time (≈300 Myr) in which case they can migrate inward and help building the central bulge. We present 3.5-7 pc resolution adaptive mesh refinement simulations of high-redshift disks including photoionization, radiation pressure, and supernovae feedback. Our modeling of radiation pressure determines the mass loading and initial velocity of winds from basic physical principles. We find that the giant clumps produce steady outflow rates comparable to and sometimes somewhat larger than their star formation rate, with velocities largely sufficient to escape the galaxy. The clumps also lose mass, especially old stars, by tidal stripping, and the stellar populations contained in the clumps hence remain relatively young (≤200 Myr), as observed. The clumps survive gaseous outflows and stellar loss, because they are wandering in gas-rich turbulent disks from which they can reaccrete gas at high rates compensating for outflows and tidal stripping, overall keeping realistic and self-regulated gaseous and stellar masses. The outflow and accretion rates have specific timescales of a few 10{sup 8} yr, as opposed to rapid and repeated dispersion and reformation of clumps. Our simulations produce gaseous outflows with velocities, densities, and mass loading consistent with observations, and at the same time suggest that the giant clumps survive for hundreds of Myr and complete their migration to the center of high-redshift galaxies. These long-lived clumps are gas-dominated and contain a moderate mass fraction of stars; they drive inside-out disk evolution, thickening, spheroid growth, and fueling of the central

  6. Estimating the mass density of neutral gas at $z < 1$

    CERN Document Server

    Natarajan, P; Natarajan, Priyamvada; Pettini, Max

    1997-01-01

    We use the relationships between galactic HI mass and B-band luminosity determined by Rao & Briggs to recalculate the mass density of neutral gas at the present epoch based on more recent measures of the galaxy luminosity function than were available to those authors. We find $\\Omega_{gas}(z=0) value, suggesting that this quantity is now reasonably secure. We then show that, if the scaling between H I mass and B-band luminosity has remained approximately constant since $z = 1$, the evolution of the luminosity function found by the Canada-France redshift survey translates to an increase of obtained quite independently from consideration of the luminosity function of Mg II absorbers at $z = 0.65$. By combining these new estimates with data from damped \\lya systems at higher redshift, it is possible to assemble a rough sketch of the evolution of $Ømega_{gas}$ over the last 90% of the age of the universe. The consumption of H I gas with time is in broad agreement with models of chemical evolution which inclu...

  7. Chemically Distinct Nuclei and Outflowing Shocked Molecular Gas in Arp 220

    CERN Document Server

    Tunnard, R; Garcia-Burillo, S; Carpio, J Graciá; Fischer, J; Fuente, A; González-Alfonso, E; Hailey-Dunsheath, S; Neri, R; Sturm, E; Usero, A; Planesas, P

    2014-01-01

    We present the results of interferometric spectral line observations of Arp 220 at 3.5mm and 1.2mm from the Plateau de Bure Interferometer (PdBI), imaging the two nuclear disks in H$^{13}$CN$(1 - 0)$ and $(3 - 2)$, H$^{13}$CO$^+(1 - 0)$ and $(3 - 2)$, and HN$^{13}$C$(3 - 2)$ as well as SiO$(2 - 1)$ and $(6 - 5)$, HC$^{15}$N$(3 - 2)$, and SO$(6_6 - 5_5)$. The gas traced by SiO$(6 - 5)$ has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO$^+(3 - 2)$. Spatial offsets $0.1''$ north and south of the continuum centre in the emission and absorption of the SiO$(6 - 5)$ P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of $\\sim40$ pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO$(6 - 5)$ and H$^{13}$CO$^+(3 - 2)$ by considering two limiting cases with regards to the H$^{13}$CO$^+$ emission ...

  8. The shocked gas of the BHR71 outflow observed by Herschel: indirect evidence for an atomic jet

    Science.gov (United States)

    Benedettini, M.; Gusdorf, A.; Nisini, B.; Lefloch, B.; Anderl, S.; Busquet, G.; Ceccarelli, C.; Codella, C.; Leurini, S.; Podio, L.

    2017-01-01

    Context. In the BHR71 region, two low-mass protostars IRS1 and IRS2 drive two distinguishable outflows. They constitute an ideal laboratory to investigate both the effects of shock chemistry and the mechanisms that led to their formation. Aims: We aim to define the global morphology of the warm gas component of the BHR71 outflow and at modelling its shocked component. Methods: We present the first far infrared Herschel images of the BHR71 outflows system in the CO (14-13), H2O (221-110), H2O (212-101) and [O i] 145 μm transitions, revealing the presence of several knots of warm, shocked gas associated with the fast outflowing gas. In two of these knots we performed a detailed study of the physical conditions by comparing a large set of transitions from several molecules to a grid of shock models. Results: The Herschel lines ratios in the outflow knots are quite similar, showing that the excitation conditions of the fast moving gas do not change significantly within the first 0.068 pc of the outflow, apart at the extremity of the southern blue-shifted lobe that is expanding outside the parental molecular cloud. Rotational diagram, spectral line profile and LVG analysis of the CO lines in knot A show the presence of two gas components: one extended, cold (T 80 K) and dense (n(H2) = 3 × 105-4 × 106 cm-3) and another compact (18''), warm (T = 1700-2200 K) with slightly lower density (n(H2) = 2 × 104-6 × 104 cm-3). In the two brightest knots (where we performed shock modelling) we found that H2 and CO are well fitted with non-stationary (young) shocks. These models, however, significantly underestimate the observed fluxes of [O i] and OH lines, but are not too far off those of H2O, calling for an additional, possibly dissociative, J-type shock component. Conclusions: Our modelling indirectly suggests that an additional shock component exists, possibly a remnant of the primary jet. Direct, observational evidence for such a jet must be searched for. Herschel is an

  9. MOSFIRE and LDSS3 spectroscopy for an [O II] Blob at z = 1.18: gas outflow and energy source

    Energy Technology Data Exchange (ETDEWEB)

    Harikane, Yuichi; Ouchi, Masami; Yuma, Suraphong; Ono, Yoshiaki [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Rauch, Michael [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Nakajima, Kimihiko, E-mail: hari@icrr.u-tokyo.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2014-10-20

    We report our Keck/MOSFIRE and Magellan/Low-Dispersion Survey Spectrograph spectroscopy for an [O II] Blob, O II B 10, that is a high-z galaxy with spatially extended [O II] λλ3726, 3729 emission over 30 kpc recently identified by a Subaru large-area narrowband survey. The systemic redshift of O II B 10 is z = 1.18 securely determined with [O III] λλ4959, 5007 and Hβ emission lines. We identify Fe II λ2587 and Mg II λλ2796, 2804 absorption lines blueshifted from the systemic redshift by 80 ± 50 and 260 ± 40 km s{sup –1}, respectively, which indicates gas outflow from O II B 10 with the velocity of ∼80-260 km s{sup –1}. This outflow velocity is comparable with the escape velocity, 250 ± 140 km s{sup –1}, estimated under the assumption of a singular isothermal halo potential profile. Some fraction of the outflowing gas could escape from the halo of O II B 10, suppressing O II B 10's star-formation (SF) activity. We estimate a mass loading factor, η, that is a ratio of mass outflow rate to SF rate, and obtain η > 0.8 ± 0.1, which is relatively high compared with low-z starbursts including U/LIRGs and active galactic nuclei (AGNs). The major energy source of the outflow is unclear with the available data. Although no signature of AGNs is found in the X-ray data, O II B 10 falls in the AGN/star-forming composite region in the line diagnostic diagrams. It is possible that the outflow is powered by SF and a type-2 AGN with narrow FWHM emission line widths of 70-130 km s{sup –1}. This is the first detailed spectroscopic study of oxygen-line blobs that includes analyses of the escape velocity, the mass loading factor, and the presence of an AGN, and is a significant step to understanding the nature of oxygen-line blobs and the relation between gas outflow and SF quenching at high redshift.

  10. Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction

    CERN Document Server

    Suutarinen, Aleksi N; Mottram, Joseph C; Fraser, Helen J; van Dishoeck, Ewine F

    2014-01-01

    Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T > 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in outflows, by comparing observations of gas-phase water to methanol (a grain surface product) towards three low-mass protostars in NGC1333. In doing so, we also quantify the amount of methanol destroyed in outflows. To do this, we make use of JCMT and Herschel-HIFI data of H2O, CH3OH and CO emission lines and compare them to RADEX non-LTE excitation simulations. We find up to one order of magnitude decrease in the column density ratio of CH3OH over H2O as the velocity increases in the line wings up to ~15 km/s. An independent decrease in X(CH3OH) with respect to CO of up to one order of magnitude is also found in these objects. We conclude that gas-phase formation of H2O must be active at high velocities (above 10 km/s, relative to the source velocity) to re-form...

  11. Constraining the dynamical importance of hot gas and radiation pressure in quasar outflows using emission line ratios

    CERN Document Server

    Stern, Jonathan; Zakamska, Nadia L; Hennawi, Joseph F

    2015-01-01

    Quasar feedback models often predict an expanding hot gas bubble which drives a galaxy-scale outflow. In many circumstances the hot gas is predicted to radiate inefficiently, making the hot bubble hard to observe directly. We present an indirect method to detect the presence of a hot bubble using hydrostatic photoionization models of the cold (10^4 K) line-emitting gas. These models assume that the cold gas is in pressure equilibrium with either the hot gas pressure or with the radiation pressure, whichever is larger. We compare our models with observations of the broad line region (BLR), the inner face of the dusty torus, the narrow line region (NLR), and the extended NLR, and thus constrain the hot gas pressure over a dynamical range of 10^5 in radius, from 0.1 pc to 10 kpc. We find that the emission line ratios observed in the average quasar spectrum are consistent with radiation-pressure-dominated models on all scales. On scales > L_AGN/c inferred for galaxy-scale outflows in luminous quasars. This appare...

  12. Detection of HCN, HCO+ and HNC in the Mrk231 molecular outflow - Dense molecular gas in the AGN wind

    CERN Document Server

    Aalto, S; Muller, S; Winters, J M; van der Werf, P; Henkel, C; Costagliola, F; Neri, R

    2011-01-01

    We detect luminous emission from HCN, HCO+ and HNC 1--0 in the QSO ULIRG Mrk~231 with the IRAM Plateau de Bure Interferometer at 1."55 by 1."28 resolution. All three lines show broad line wings - which are particularly prominent for HCN. Velocities are found to be similar (750 km/s) to those found for CO 1-0. This is the first time bright HCN, HCO+ and HNC emission has been detected in a large-scale galactic outflow. We find that both the blue- and red-shifted line wings are spatially extended by at least 0."75 (700 pc) in a north-south direction. The line wings are brighter (relative to the line center intensity) in HCN than in CO 1-0 and line ratios suggest that the molecular outflow consists of dense (n>10E4 cmE-3) and clumpy gas with a high HCN abundance X(HCN)>10E-8. These properties are consistent with the molecular gas being compressed and fragmented by shocks in the outflow. Alternatively, HCN is instead pumped by mid-IR continuum, but we propose that this effect is not strong for the spatially extend...

  13. CHEMICALLY DISTINCT NUCLEI AND OUTFLOWING SHOCKED MOLECULAR GAS IN Arp 220

    Energy Technology Data Exchange (ETDEWEB)

    Tunnard, R.; Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Garcia-Burillo, S.; Fuente, A.; Usero, A.; Planesas, P. [Observatorio Astronómico Nacional, Observatorio de Madrid, Alfonso XII, 3, E-28014 Madrid (Spain); Carpio, J. Graciá; Hailey-Dunsheath, S.; Sturm, E. [Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstraße 1, D-85748 Garching (Germany); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Ave SW, Washington, DC 20375 (United States); González-Alfonso, E.; Neri, R., E-mail: richard.tunnard.13@ucl.ac.uk [Universidad de Alcalá de Henares, Departamento de Física y Matemáticas, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain)

    2015-02-10

    We present the results of interferometric spectral line observations of Arp 220 at 3.5 mm and 1.2 mm from the Plateau de Bure Interferometer, imaging the two nuclear disks in H{sup 13}CN(1-0) and (3-2), H{sup 13}CO{sup +}(1-0) and (3-2), and HN{sup 13}C(3-2) as well as SiO(2-1) and (6-5), HC{sup 15}N(3-2), and SO(6{sub 6}-5{sub 5}). The gas traced by SiO(6-5) has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO{sup +}(3-2). Spatial offsets 0.''1 north and south of the continuum center in the emission and absorption of the SiO(6-5) P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of ∼40 pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO(6-5) and H{sup 13}CO{sup +}(3-2) by considering two limiting cases with regards to the H{sup 13}CO{sup +} emission throughout our analysis. Large velocity gradient modeling is used to constrain the physical conditions of the gas and to infer abundance ratios in the two nuclei. Our most conservative lower limit on the [H{sup 13}CN]/[H{sup 13}CO{sup +}] abundance ratio is 11 in the WN, compared with 0.10 in the eastern nucleus (EN). Comparing these ratios to the literature we argue on chemical grounds for an energetically significant active galactic nucleus in the WN driving either X-ray or shock chemistry, and a dominant starburst in the EN.

  14. GASDUC-3: a gas pipeline with neutralization of greenhouse gases

    Energy Technology Data Exchange (ETDEWEB)

    D' Oliveira, Celso A.; Paula, Eliane H. de; Freire, Dilian A.D. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2009-07-01

    PETROBRAS seeks to develop its projects following the contemporary premises of sustainable development. The Cabiunas-REDUC-3 Gas Pipeline (GASDUC-3), an undertaking from the Transportadora Associada de Gas - TAG (Associated Gas Transporter) in progress by PETROBRAS, is an example showing that interfacing with the environment can overcome legal questions to reach the realm of awareness and community spirit. In addition to the many programs directed specifically towards the fulfillment of environmental regulations, as defined by competent agencies, the GASDUC-3 is also inserted in the Carbon Free Program. In the Carbon Free Program, all the GHG emissions into the atmosphere during the construction of the gas pipeline will be compensated for with the neutralization of carbon through reforestation. Such initiative is considered unheard of in works with pipelines worldwide. An inventory that quantified the emission of GHG during the implementation of GASDUC-3 made it possible to quantify the reforestation to be implemented and to calculate the number of native species to be planted for absorption - during the course of their growth - of this same amount of carbon dioxide from the atmosphere. The trees are being planted especially in Permanent Preservation Areas (PPA), located in the Unidades de Conservacao do Bioma Mata Atlantica (Conservation Units of the Atlantic Forest Biome), inside the influence region of the gas pipeline, in accordance with the competent environmental agencies and owners. In this way, in addition to fixing carbon and contributing to the deceleration of global warming, the project also cooperates with the preservation of hydro and soil resources and the local and regional biodiversity. The recapturing of the already emitted GHG through reforestation faces bureaucratic and economic difficulties in order to be implemented, different from the emission reduction projects which are widely disseminated by means of Clean Development Mechanisms (CDM

  15. Constraint on the Inflow/outflow Rates in Star-forming Galaxies at z ~ 1.4 from Molecular Gas Observations

    Science.gov (United States)

    Seko, Akifumi; Ohta, Kouji; Yabe, Kiyoto; Hatsukade, Bunyo; Akiyama, Masayuki; Tamura, Naoyuki; Iwamuro, Fumihide; Dalton, Gavin

    2016-12-01

    We constrain the rate of gas inflow into and outflow from a main-sequence star-forming galaxy at z∼ 1.4 by fitting a simple analytic model for the chemical evolution in a galaxy to the observational data of the stellar mass, metallicity, and molecular gas mass fraction. The molecular gas mass is derived from CO observations with a metallicity-dependent CO-to-H2 conversion factor, and the gas metallicity is derived from the Hα and [N ii]λ 6584 emission line ratio. Using a stacking analysis of CO integrated intensity maps and the emission lines of Hα and [N ii], the relation between stellar mass, metallicity, and gas mass fraction is derived. We constrain the inflow and outflow rates with least-chi-square fitting of a simple analytic chemical evolution model to the observational data. The best-fit inflow and outflow rates are ∼1.7 and ∼0.4 in units of star formation rate (SFR), respectively. The inflow rate is roughly comparable to the sum of the SFR and outflow rate, which supports the equilibrium model for galaxy evolution; i.e., all inflow gas is consumed by star formation and outflow.

  16. Gas-phase recombination, grain neutralization and cosmic-ray ionization in diffuse gas

    CERN Document Server

    Liszt, H S

    2003-01-01

    Atomic ions are mostly neutralized by small grains (or PAH molecules) in current theories of heating and cooling in cool diffuse clouds; in the main they do not recombine with free electrons. This alters the ionization balance by depressing n(H+) and n(He+) while carbon generally remains nearly fully once-ionized: charge exchange with atomic oxygen and formation of H2 and OH also depress n(H+) in partly molecular gas. Seemingly restrictive empirical limits on the cosmic ray ionization rate of hydrogen ($\\zeta_H$) are relaxed and faster rates are favored in a wide range of circumstances, when grain neutralization is recognized. Maintenance of the proton density at levels needed to reproduce observations of HD requires $\\zeta_H$ at least 2x10^{-16} s^{-1}, but such models naturally explain the presence of both HD and H3^+ in relatively tenuous H I clouds. In dense gas, a higher ionization rate can account for high observed fractions of atomic hydrogen, and recognition of the effects of grain neutralization can ...

  17. Three-dimensional modeling of the neutral gas depletion effect in a helicon discharge plasma

    Science.gov (United States)

    Kollasch, Jeffrey; Schmitz, Oliver; Norval, Ryan; Reiter, Detlev; Sovinec, Carl

    2016-10-01

    Helicon discharges provide an attractive radio-frequency driven regime for plasma, but neutral-particle dynamics present a challenge to extending performance. A neutral gas depletion effect occurs when neutrals in the plasma core are not replenished at a sufficient rate to sustain a higher plasma density. The Monte Carlo neutral particle tracking code EIRENE was setup for the MARIA helicon experiment at UW Madison to study its neutral particle dynamics. Prescribed plasma temperature and density profiles similar to those in the MARIA device are used in EIRENE to investigate the main causes of the neutral gas depletion effect. The most dominant plasma-neutral interactions are included so far, namely electron impact ionization of neutrals, charge exchange interactions of neutrals with plasma ions, and recycling at the wall. Parameter scans show how the neutral depletion effect depends on parameters such as Knudsen number, plasma density and temperature, and gas-surface interaction accommodation coefficients. Results are compared to similar analytic studies in the low Knudsen number limit. Plans to incorporate a similar Monte Carlo neutral model into a larger helicon modeling framework are discussed. This work is funded by the NSF CAREER Award PHY-1455210.

  18. Complicated Structure of Interacting Young Binary System: Outflows and Gas-Streams

    Science.gov (United States)

    Pyo, Tae-Soo; Hayashi, M.; Beck, T. L.; Chris, C. J.; Takami, M.

    2014-07-01

    It is important to understand the formation and evolution of the young binary system because many young stars are born in binary or multiple systems. We report recent discovery of binary jet and wind from UY Aur system with high-angular resolution observation by using NIFS (NIR Integral Field Spectrograph) /GEMINI combined with adaptive optics system, Altair. The primary, UY Aur A, reveals widely opened wind while the secondary, UY Aur B, shows small jets in NIR [Fe II] emission. Outflows from low-mass young binary or multiple systems have been observed from a few tens of samples. Outflows are closely related mass accretion. Many simulations show an accretion flow toward the individual circumstellar disks from the outer circumbinary disk as well as a stream bridge between the circumstellar disks. We will discuss how to use TMT and ALMA for anatomy of young binary systems.

  19. GMASS ultradeep spectroscopy of galaxies at z ~ 2 - VII. Star formation, extinction, and gas outflows from UV spectra

    CERN Document Server

    Talia, M; Cimatti, A; Kurk, J; Berta, S; Bolzonella, M; Cassata, P; Daddi, E; Dickinson, M; Franceschini, A; Halliday, C; Pozzetti, L; Renzini, A; Rodighiero, G; Rosati, P; Zamorani, G

    2011-01-01

    We use rest-frame UV spectroscopy to investigate the properties related to large-scale gas outflows, and to the dust extinction and star-formation rates of a sample of z ~ 2 star-forming galaxies from the Galaxy Mass Assembly ultradeep Spectroscopic Survey (GMASS). Dust extinction is estimated from the rest-frame UV continuum slope and used to obtain dust-corrected star-formation rates for the galaxies of the sample. For the entire sample, a mean value of the continuum slope = -1.11 \\pm 0.44 (r.m.s.) was derived, while the average SFR was found to be = 52 \\pm 48 M_sun/yr (r.m.s.). A positive correlation between SFR and stellar mass was observed, in agreement with other works, the logarithmic slope of the relation being 1.10 \\pm 0.10. Low-ionization absorption lines, associated with the interstellar medium, were found to be blueshifted, with respect to the rest frame of the system, which indicates that there is outflowing gas with typical velocities of the order of ~ 100 km/s. Finally, investigating correlat...

  20. Investigation of Sterilization Mechanism for Geobacillus stearothermophilus Spores with Plasma-Excited Neutral Gas

    Science.gov (United States)

    Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

    2015-09-01

    We investigate the mechanism of the sterilization with plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals are separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas uses humidified mixture of nitrogen and oxygen. Geobacillus stearothermophilus spores and tyrosine which is amino acid are treated by the plasma-excited neutral gas. Shape change of the treated spore is observed by SEM, and chemical modification of the treated tyrosine is analyzed by HPLC. As a result, the surface of the treated spore shows depression. Hydroxylation and nitration of tyrosine are shown after the treatment. For these reasons, we believe that the sterilization with plasma-excited neutral gas results from the deformation of spore structure due to the chemical modification of amino acid.

  1. The Stefan outflow in a multicomponent vapor-gas atmosphere around a droplet and its role for cloud expansion

    CERN Document Server

    Kuchma, A E; Martyukova, D S

    2016-01-01

    A new comprehensive analysis of Stefan's flow caused by a free growing droplet in vapor-gas atmosphere with several condensing components is presented. This analysis, based on the nonstationary heat and material balance and diffusion transport equations, shows the appearance of the Stefan inflow in the vicinity of the growing droplet and the outflow at large distances from the droplet as a consequence of nonisothermal condensation. For an ensemble of droplets in the atmospheric cloud, this flow provides an increase of the total volume of the cloud, which can be treated as cloud thermal expansion and leads to floating the cloud as a whole due to buoyancy. We have formulated the self-similar solutions of the nonstationary diffusion and heat conduction equations for a growing multicomponent droplet and have derived analytical expressions for the nonstationary velocity profile of Stefan's flow and the expansion volume of the vapor-gas mixture around the growing droplet. To illustrate the approach, we computed the...

  2. Molecules in Bipolar Outflows

    CERN Document Server

    Tafalla, Mario

    2012-01-01

    Bipolar outflows constitute some of the best laboratories to study shock chemistry in the interstellar medium. A number of molecular species have their abundance enhanced by several orders of magnitude in the outflow gas, likely as a combined result of dust mantle disruption and high temperature gas chemistry, and therefore become sensitive indicators of the physical changes taking place in the shock. Identifying these species and understanding their chemical behavior is therefore of high interest both to chemical studies and to our understanding of the star-formation process. Here we review some of the recent progress in the study of the molecular composition of bipolar outflows, with emphasis in the tracers most relevant for shock chemistry. As we discuss, there has been rapid progress both in characterizing the molecular composition of certain outflows as well as in modeling the chemical processes likely involved. However, a number of limitations still affect our understanding of outflow chemistry. These i...

  3. NIHAO IX: the role of gas inflows and outflows in driving the contraction and expansion of cold dark matter haloes

    Science.gov (United States)

    Dutton, Aaron A.; Macciò, Andrea V.; Dekel, Avishai; Wang, Liang; Stinson, Gregory; Obreja, Aura; Di Cintio, Arianna; Brook, Chris; Buck, Tobias; Kang, Xi

    2016-09-01

    We use ˜100 cosmological galaxy formation `zoom-in' simulations using the smoothed particle hydrodynamics code GASOLINE to study the effect of baryonic processes on the mass profiles of cold dark matter haloes. The haloes in our study range from dwarf (M200 ˜ 1010 M⊙) to Milky Way (M200 ˜ 1012 M⊙) masses. Our simulations exhibit a wide range of halo responses, primarily varying with mass, from expansion to contraction, with up to factor ˜10 changes in the enclosed dark matter mass at 1 per cent of the virial radius. Confirming previous studies, the halo response is correlated with the integrated efficiency of star formation: ɛSF ≡ (Mstar/M200)/(Ωb/Ωm). In addition, we report a new correlation with the compactness of the stellar system: ɛR ≡ r1/2/R200. We provide an analytic formula depending on ɛSF and ɛR for the response of cold dark matter haloes to baryonic processes. An observationally testable prediction is that, at fixed mass, larger galaxies experience more halo expansion, while the smaller galaxies more halo contraction. This diversity of dark halo response is captured by a toy model consisting of cycles of adiabatic inflow (causing contraction) and impulsive gas outflow (causing expansion). For net outflow, or equal inflow and outflow fractions, f, the overall effect is expansion, with more expansion with larger f. For net inflow, contraction occurs for small f (large radii), while expansion occurs for large f (small radii), recovering the phenomenology seen in our simulations. These regularities in the galaxy formation process provide a step towards a fully predictive model for the structure of cold dark matter haloes.

  4. NIHAO - VIII. Circum-galactic medium and outflows - The puzzles of H I and O VI gas distributions

    Science.gov (United States)

    Gutcke, Thales A.; Stinson, Greg S.; Macciò, Andrea V.; Wang, Liang; Dutton, Aaron A.

    2017-01-01

    We study the hot and cold circum-galactic medium (CGM) of 86 galaxies of the cosmological, hydrodynamical simulation suite, Numerical Investigation of a Hundred Astrophysical Objects (NIHAO). NIHAO allows a study of how the z = 0 CGM varies across five orders of magnitude of stellar mass using O VI and H I as proxies for hot and cold gas. The cool H I covering fraction and column density profiles match observations well, particularly in the inner CGM. O VI shows increasing column densities with mass, a trend seemingly echoed in the observations. As in multiple previous simulations, the O VI column densities in simulations are lower than observed and optically thick H I does not extend as far out as in observations. We take a look at the collisional ionization fraction of O VI as a function of halo mass. We make observable predictions of the bipolarity of outflows and their effect on the general shape of the CGM. Bipolar outflows can be seen out to around 40 kpc in intermediate- and low-mass haloes (MHalo < 1011 M⊙), but outside that radius, the CGM is too well mixed to detect an elongated shape. Larger haloes have extended gas discs beyond the stellar disc that dominate the shape of the inner CGM. The simulated CGM is remarkably spherical even in low-mass simulations. The chemical enrichment of both halo and disc gas follow expected increasing trends as a function of halo mass that are well fit with power laws. These relations can be used in non-hydrodynamic models, such as semi-analytic models.

  5. Neutral gas sympathetic cooling of an ion in a Paul trap

    CERN Document Server

    Chen, Kuang; Hudson, Eric R

    2013-01-01

    A single ion immersed in a neutral buffer gas is studied. An analytical model is developed that gives a complete description of the dynamics and steady-state properties of the ions. An extension of this model, using techniques borrowed from the mathematics of finance, is used to explain the recent observation of non-Maxwellian statistics for these systems. Taken together, these results offer an explanation of the longstanding issues associated with sympathetic cooling of an ion by a neutral buffer gas.

  6. Constraint on the inflow/outflow rates in star-forming galaxies at z~1.4 from molecular gas observations

    CERN Document Server

    Seko, Akifumi; Yabe, Kiyoto; Hatsukade, Bunyo; Akiyama, Masayuki; Tamura, Naoyuki; Iwamuro, Fumihide; Dalton, Gavin

    2016-01-01

    We constrain the rate of gas inflow into and outflow from a main-sequence star-forming galaxy at z~1.4 by fitting a simple analytic model for the chemical evolution in a galaxy to the observational data of the stellar mass, metallicity, and molecular gas mass fraction. The molecular gas mass is derived from CO observations with a metallicity-dependent CO-to-H2 conversion factor, and the gas metallicity is derived from the H{\\alpha} and [NII]{\\lambda} 6584 emission line ratio. Using a stacking analysis of CO integrated intensity maps and the emission lines of H{\\alpha} and [NII], the relation between stellar mass, metallicity, and gas mass fraction is derived. We constrain the inflow and outflow rates with least-chi-square fitting of a simple analytic chemical evolution model to the observational data. The best-fit inflow and outflow rates are ~1.7 and ~0.4 in units of star-formation rate, respectively. The inflow rate is roughly comparable to the sum of the star-formation rate and outflow rate, which supports...

  7. Understanding of Neutral Gas Transport in the Alcator C-Mod Tokamak Divertor

    Energy Technology Data Exchange (ETDEWEB)

    D.P. Stotler; C.S. Pitcher; C.J. Boswell; B. LaBombard; J.L. Terry; J.D. Elder; S. Lisgo

    2002-05-07

    A series of experiments on the effect of divertor baffling on the Alcator C-Mod tokamak provides stringent tests on models of neutral gas transport in and around the divertor region. One attractive feature of these experiments is that a trial description of the background plasma can be constructed from experimental measurements using a simple model, allowing the neutral gas transport to be studied with a stand-alone code. The neutral-ion and neutral-neutral elastic scattering processes recently added to the DEGAS 2 Monte Carlo neutral transport code permit the neutral gas flow rates between the divertor and main chamber to be simulated more realistically than before. Nonetheless, the simulated neutral pressures are too low and the deuterium Balmer-alpha emission profiles differ qualitatively from those measured, indicating an incomplete understanding of the physical processes involved in the experiment. Some potential explanations are examined and opportunities for future exploration a re highlighted. Improvements to atomic and surface physics data and models will play a role in the latter.

  8. Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas

    CERN Document Server

    Garcia-Burillo, S; Usero, A; Aalto, S; Krips, M; Viti, S; Alonso-Herrero, A; Hunt, L K; Schinnerer, E; Baker, A J; Casasola, F Boone V; Colina, L; Costagliola, F; Eckart, A; Fuente, A; Henkel, C; Labiano, A; Martin, S; Marquez, I; Muller, S; Planesas, P; Almeida, C Ramos; Spaans, M; Tacconi, L J; van der Werf, P P

    2014-01-01

    We investigate the fueling and the feedback of star formation and nuclear activity in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We have used ALMA to map the emission of a set of dense molecular gas tracers (CO(3-2), CO(6-5), HCN(4-3), HCO+(4-3) and CS(7-6)) and their underlying continuum emission in the central r ~ 2kpc of NGC1068 with spatial resolutions ~ 0.3"-0.5" (~ 20-35pc). Molecular line and dust continuum emissions are detected from a r ~ 200pc off-centered circumnuclear disk (CND), from the 2.6kpc-diameter bar region, and from the r ~ 1.3kpc starburst (SB) ring. Most of the emission in HCO+, HCN and CS stems from the CND. Molecular line ratios show dramatic order-of-magnitude changes inside the CND that are correlated with the UV/X-ray illumination by the AGN, betraying ongoing feedback. The gas kinematics from r ~ 50pc out to r ~ 400pc reveal a massive (M_mol ~ 2.7 (+0.9, -1.2) x 10^7 Msun) outflow in all molec...

  9. A Radio Study of the Seyfert Galaxy IC 5063 Evidence for Fast Gas Outflow

    CERN Document Server

    Morganti, R; Tsvetanov, Z I

    1997-01-01

    New radio continuum (8 GHz and 1.4 GHz) and HI 21 cm line observations of the Seyfert 2 galaxy IC 5063 (PKS 2048-572) were obtained with the Australia Telescope Compact Array (ATCA). The 8 GHz image reveals a linear triple structure (~4'', 1.5 kpc) oriented perpendicular to the optical polarization position angle. It is aligned with the inner dust lane and shows strong morphological association with the narrow emission line region (NLR). At 21 cm, very broad (~700 km/s) HI absorption is observed against the strong continuum source. This absorption is almost entirely blueshifted, indicating a fast net outflow, but a faint and narrow redshifted component is also present. In IC 5063 we see clear evidence for strong shocks resulting from the radio plasma-ISM interaction in the central few kpc. However, the energy flux in the radio plasma is an order of magnitude smaller than the energy emitted in emission lines. Thus, shocks are unlikely to account solely for the global ionization of the emission line region, par...

  10. FRC translation experiment into the neutral gas background in the FIX device

    Energy Technology Data Exchange (ETDEWEB)

    Okubo, Mamoru; Kodera, Fuji; Asai, Tomohiko; Okada, Shigefumi; Goto, Seiichi [Osaka Univ., Graduate School of Engineering, Plasma Physics Laboratory, Osaka (Japan)

    2003-07-01

    Translating an FRC plasma through a neutral gas background is equivalent to the injection of a warm neutral beam end-on into the FRC. Controlling a translated FRC density and rethermalization of the kinetic energy of that are expected by gas puffing without complex NBI device. We carried out FRC translation experiment into the neutral gas background based on this point of view. In the FIX device, the FRC produced in the quartz formation region is translated into the metal confinement region. The translated FRC is reflected by the downstream mirror field. The FRC reaches equilibrium state after one or two bounces. Typical translation velocity of FIX-FRC is about 1.5 x 10{sup 5} m/sec, which is equivalent to a 200 eV incident neutral D beam. The neutral gas (D{sub 2}) pressures of {approx}10{sup -2} Pa averaged inside the confinement region can be introduced using a piezo electric valve which is installed on the end of FIX-device. An FRC is translated into neutral gas background whose averaged density is about 1{approx}3 x 10{sup -2} Pa. The mean free path {lambda}{sub ionize} ({approx}0.1 m) of D{sub 2} is shorter than FRC separatrix length l{sub s} under the parameters of FIX-FRC plasma. As the result of this experiment, the radii of the FRC increase 10{approx}20 % of those of normal FRC after the 1st reflection. An increasing in the particle number inside the separatrix is observed after the translation into the neutral gas background. The total energy inside the FRC after translation is also observed to increase a little. (author)

  11. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, A., E-mail: akirkpatrick@exogenesis.us [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States); Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J. [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States)

    2013-07-15

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  12. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    Science.gov (United States)

    Kirkpatrick, A.; Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J.

    2013-07-01

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  13. Heating of the molecular gas in the massive outflow of the local ultraluminous-infrared and radio-loud galaxy 4C12.50

    CERN Document Server

    Dasyra, K M; Novak, G S; Bremer, M; Spinoglio, L; Santaella, M Pereira; Salome, P; Falgarone, E

    2014-01-01

    We present a comparison of the molecular gas properties in the outflow vs. in the ambient medium of the local prototype radio-loud and ultraluminous-infrared galaxy 4C12.50 (IRAS13451+1232), using new data from the IRAM Plateau de Bure interferometer and 30m telescope, and the Herschel space telescope. Previous H_2 (0-0) S(1) and S(2) observations with the Spitzer space telescope had indicated that the warm (~400K) molecular gas in 4C12.50 is made up of a 1.4(+-0.2)x10^8 M_sun ambient reservoir and a 5.2(+-1.7)x10^7 M_sun outflow. The new CO(1-0) data cube indicates that the corresponding cold (25K) H_2 gas mass is 1.0(+-0.1)x10^10 M_sun for the ambient medium and = 30 times higher in the outflow than in the ambient medium, indicating that a non-negligible fraction of the accelerated gas is heated to temperatures at which star formation is inefficient. This conclusion is robust against the use of different alpha factor values, and/or different warm gas tracers (H_2 vs. H_2 plus CO): with the CO-probed gas mas...

  14. Hydrocarbon anomaly in soil gas as near-surface expressions of upflows and outflows in geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Ong, H.L.; Higashihara, M.; Klusman, R.W.; Voorhees, K.J.; Pudjianto, R.; Ong, J

    1996-01-24

    A variety of hydrocarbons, C1 - C12, have been found in volcanic gases (fumarolic) and in geothermal waters and gases. The hydrocarbons are thought to have come from products of pyrolysis of kerogen in sedimentary rocks or they could be fed into the geothermal system by the recharging waters which may contain dissolved hydrocarbons or hydrocarbons extracted by the waters from the rocks. In the hot geothermal zone, 300°+ C, many of these hydrocarbons are in their critical state. It is thought that they move upwards due to buoyancy and flux up with the upflowing geothermal fluids in the upflow zones together with the magmatic gases. Permeability which could be provided by faults, fissures, mini and micro fractures are thought to provide pathways for the upward flux. A sensitive technique (Petrex) utilizing passive integrative adsorption of the hydrocarbons in soil gas on activated charcoal followed by desorption and analysis of the hydrocarbons by direct introduction mass spectrometry allows mapping of the anomalous areas. Surveys for geothermal resources conducted in Japan and in Indonesia show that the hydrocarbon anomaly occur over known fields and over areas strongly suspected of geothermal potential. The hydrocarbons found and identified were n-paraffins (C7-C9) and aromatics (C7-C8). Detection of permeable, i.e. active or open faults, parts of older faults which have been reactivated, e.g. by younger intersecting faults, and the area surrounding these faulted and permeable region is possible. The mechanism leading to the appearance of the hydrocarbon in the soil gas over upflow zones of the geothermal reservoir is proposed. The paraffins seems to be better pathfinders for the location of upflows than the aromatics. However the aromatics may, under certain circumstances, give better indications of the direction of the outflow of the geothermal system. It is thought that an upflow zone can be

  15. Effects of humidity on sterilization of Geobacillus stearothermophilus spores with plasma-excited neutral gas

    Science.gov (United States)

    Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

    2015-06-01

    We investigate the effects of relative humidity on the sterilization process using a plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals were separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas is nitrogen mixed with 0.1% oxygen, and the relative humidity in the source gas is controlled by changing the mixing ratio of water vapor. The relative humidity near the sample in the reactor chamber is controlled by changing the sample temperature. As a result, the relative humidity near the sample should be kept in the range from 60 to 90% for the sterilization of Geobacillus stearothermophilus spores. When the relative humidity in the source gas increases from 30 to 90%, the sterilization effect is enhanced by the same degree.

  16. Measurement of neutral gas temperature in a 13.56 MHz inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jayapalan, Kanesh K.; Chin, Oi Hoong [Plasma Technology Research Centre, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Measuring the temperature of neutrals in inductively coupled plasmas (ICP) is important as heating of neutral particles will influence plasma characteristics such as the spatial distributions of plasma density and electron temperature. Neutral gas temperatures were deduced using a non-invasive technique that combines gas actinometry, optical emission spectroscopy and simulation which is described here. Argon gas temperature in a 13.56 MHz ICP were found to fall within the range of 500 − 800 K for input power of 140 − 200 W and pressure of 0.05 − 0.2 mbar. Comparing spectrometers with 0.2 nm and 0.5 nm resolution, improved fitting sensitivity was observed for the 0.2 nm resolution.

  17. A general model for Io's neutral gas clouds. I - Mathematical description

    Science.gov (United States)

    Smyth, W. H.; Combi, M. R.

    1988-01-01

    A general mathematical formalism for calculating the physical properties of any of Io's neutral gas clouds (Na, K, O, S, SO2) is presented. The dynamical effects of both the gravitational fields of Io and Jupiter and solar radiation pressure are included, in addition to the many complex space- and time-dependent interactions that occur between the neutral clouds and the plasma torus. The importance of this new model in studying both the plasma conditions prevalent in the inner planetary magnetosphere and the nature of Io's local atmosphere is discussed. A numerical method for evaluating the physical properties of the neutral clouds using the new model is described.

  18. Dense Ionized and Neutral Gas Surrounding Sgr A*

    CERN Document Server

    Shukla, Hemant; Scoville, N Z

    2004-01-01

    We present high resolution H41a hydrogen recombination line observations of the 1.2' (3 pc) region surrounding Sgr A* at 92 GHz using the OVRO Millimeter Array with an angular resolution of 7" x 3" and velocity resolution of 13 km/s. New observations of H31a, H35a, H41a, and H44a lines were obtained using the NRAO 12-m telescope, and their relative line strengths are interpreted in terms of various emission mechanisms. These are the most extensive and most sensitive observations of recombination line to date. Observations of HCO+ (1 - 0) transition at 89 GHz are also obtained simultaneously with a 40% improved angular resolution and 4-15 times improved sensitivity over previous observations, and the distribution and kinematics of the dense molecular gas in the circumnuclear disk (CND) are mapped and compared with those of the ionized gas. The line brightness ratios of the hydrogen recombination lines are consistent with purely spontaneous emission from 7000 K gas with n_e = 20,000 cm$^{-3}$ near LTE condition...

  19. Neutral gas sympathetic cooling of an ion in a Paul trap.

    Science.gov (United States)

    Chen, Kuang; Sullivan, Scott T; Hudson, Eric R

    2014-04-11

    A single ion immersed in a neutral buffer gas is studied. An analytical model is developed that gives a complete description of the dynamics and steady-state properties of the ions. An extension of this model, using techniques employed in the mathematics of economics and finance, is used to explain the recent observation of non-Maxwellian statistics for these systems. Taken together, these results offer an explanation of the long-standing issues associated with sympathetic cooling of an ion by a neutral buffer gas.

  20. Mapping Large-Scale Gaseous Outflows in Ultraluminous Infrared Galaxies with Keck II ESI Spectra: Spatial Extent of the Outflow

    CERN Document Server

    Martin, C L

    2006-01-01

    The kinematics of neutral gas and warm ionized gas have been mapped in one-dimension across ultraluminous starburst galaxies using interstellar absorption and emission lines, in Keck II ESI spectra. Blue-shifted absorption is found along more of the slit than anticipated, exceeding scales of 15 kpc across several systems. The large velocity gradient measured across some of these outflows is inconsistent with a flow diverging from the central starburst -- angular momentum conservation reduces the rotational velocity of an outflow as it expands. More widespread star formation, likely triggered by the merger, probably drives these outflows, although some models suggest the collision itself could generate a wind by shock heating interstellar gas throughout the disk. Young mergers with separated nuclei present the highest outflow masses, due mainly to the larger area over which the cool gas can be detected. In a typical ULIG, the mass carried by the cool phase of the outflow is around 10^8Msun, or a few percent of...

  1. COSMIC RAYS CAN DRIVE STRONG OUTFLOWS FROM GAS-RICH HIGH-REDSHIFT DISK GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Hanasz, M.; Kowalik, K.; Wóltański, D. [Centre for Astronomy, Nicolaus Copernicus University, Faculty of Physics, Astronomy and Informatics, Grudziadzka 5, PL-87100 Toruń (Poland); Lesch, H. [Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 München (Germany); Naab, T. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching bei München (Germany); Gawryszczak, A., E-mail: mhanasz@astri.uni.torun.pl [Poznań Supercomputing and Networking Centre, ul. Noskowskiego 10, PL-61-704 Poznań (Poland)

    2013-11-10

    We present simulations of the magnetized interstellar medium (ISM) in models of massive star-forming (40 M {sub ☉} yr{sup –1}) disk galaxies with high gas surface densities (Σ{sub gas} ∼ 100 M {sub ☉} pc{sup –2}) similar to observed star-forming high-redshift disks. We assume that type II supernovae deposit 10% of their energy into the ISM as cosmic rays (CRs) and neglect the additional deposition of thermal energy or momentum. With a typical Galactic diffusion coefficient for CRs (3 × 10{sup 28} cm{sup 2} s{sup –1}), we demonstrate that this process alone can trigger the local formation of a strong low-density galactic wind maintaining vertically open field lines. Driven by the additional pressure gradient of the relativistic fluid, the wind speed can exceed 10{sup 3} km s{sup –1}, much higher than the escape velocity of the galaxy. The global mass loading, i.e., the ratio of the gas mass leaving the galactic disk in a wind to the star formation rate, becomes of order unity once the system has settled into an equilibrium. We conclude that relativistic particles accelerated in supernova remnants alone provide a natural and efficient mechanism to trigger winds similar to observed mass-loaded galactic winds in high-redshift galaxies. These winds also help in explaining the low efficiencies for the conversion of gas into stars in galaxies, as well as the early enrichment of the intergalactic medium with metals. This mechanism may be at least of similar importance to the traditionally considered momentum feedback from massive stars and thermal and kinetic feedback from supernova explosions.

  2. Extended Warm Gas in the ULIRG Mrk273: Galactic Outflows and Tidal Debris

    CERN Document Server

    Zaurin, Javier Rodriguez; Rupke, David S N; Veilleux, Sylvain; Spoon, Henrik W W; Chiaberge, Marco; Almeida, Cristina Ramos; Batcheldor, Dan; Sparks, William B

    2014-01-01

    We present new HST ACS medium- and narrow-band images and long-slit, optical (4000 - 7200A) spectra obtained using the Isaac Newton Telescope (INT) on La Palma, of the merging system Mrk273. The HST observations sample the [OIII]4959,5007 emission from the galaxy and the nearby continuum. The images show that the morphologies of the extended continuum and the ionised gas emission from the galaxy are decoupled, extending almost perpendicular to each other. In particular, we detect for the first time a spectacular structure of ionised gas in the form of filaments extending ~23 kpc to the east of the nuclear region. The quiescent ionised gas kinematics at these locations suggests that these filaments are tidal debris left over from a secondary merger event that are illuminated by an AGN in the nuclear regions. The images also reveal a complex morphology in the nuclear region of the galaxy for both the continuum and the [OIII] emission. Kinematic disturbance, in the form of broad (FWHM > 500 km s-1) and/or strong...

  3. Direct Evidence for Outflow of Metal-enriched Gas Along the Radio Jets of Hydra A

    CERN Document Server

    Kirkpatrick, C C; Cavagnolo, K W; McNamara, B R; David, L P; Nulsen, P E J; Wise, M W

    2009-01-01

    Using deep Chandra observations of the Hydra A galaxy cluster, we examine the metallicity structure near the central galaxy and along its powerful radio source. We show that the metallicity of the intracluster medium is enhanced by up to 0.2 dex along the radio jets and lobes compared to the metallicity of the undisturbed gas. The enhancements extend from a radius of 20 kpc from the central galaxy to a distance of ~ 120 kpc. We estimate the total iron mass that has been transported out of the central galaxy to be between 2 x 10^7 M_sun and 7 x 10^7 M_sun which represents 10% - 20% of the iron mass within the central galaxy. The energy required to lift this gas is roughly 1% to 5% of the total energetic output of the AGN. Evidently, Hydra A's powerful radio source is able to redistribute metal-enriched, low entropy gas throughout the core of the galaxy cluster. The short re-enrichment time scale < 10^9 yr implies that the metals lost from the central galaxy will be quickly replenished.

  4. Analytical model of neutral gas shielding for hydrogen pellet ablation

    Energy Technology Data Exchange (ETDEWEB)

    Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)

    2001-11-01

    A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)

  5. Baryonic Distributions in Galaxy Dark Matter Haloes I: New Observations of Neutral and Ionized Gas Kinematics

    CERN Document Server

    Richards, Emily E; Barnes, K L; Staudaher, S; Dale, D A; Braun, T T; Wavle, D C; Dalcanton, J J; Bullock, J S; Chandar, R

    2016-01-01

    We present a combination of new and archival neutral hydrogen (HI) observations and new ionized gas spectroscopic observations for sixteen galaxies in the statistically representative EDGES kinematic sample. HI rotation curves are derived from new and archival radio synthesis observations from the Very Large Array (VLA) as well as processed data products from the Westerbork Radio Synthesis Telescope (WSRT). The HI rotation curves are supplemented with optical spectroscopic integral field unit (IFU) observations using SparsePak on the WIYN 3.5 m telescope to constrain the central ionized gas kinematics in twelve galaxies. The full rotation curves of each galaxy are decomposed into baryonic and dark matter halo components using 3.6$\\mu$m images from the Spitzer Space Telescope for the stellar content, the neutral hydrogen data for the atomic gas component, and, when available, CO data from the literature for the molecular gas component. Differences in the inferred distribution of mass are illustrated under fixe...

  6. Outflows of very ionized gas in the center of Seyfert galaxies: kinematics and physical conditions

    CERN Document Server

    Rodríguez-Ardila, A; Viegas, S; Grünwald, R; Rodriguez-Ardila, Alberto

    2006-01-01

    Mid-resolution spectra are used to deduce the size and kinematics of the coronal gas in a sample of Seyfert galaxies by means of observations of the [FeXI], [FeX], [FeVII], [SiVI] and [SiVII] lines. These coronal lines (CL) extend from the unresolved nucleus up to a few tens to a few hundreds of parsecs. The region of the highest ionized ions studied, [FeXI] and [FeX], is the least spatially extended, and concentrates at the center; intermediate ionization lines extend from the nucleus up to a few tens to a few hundred parsecs; lower [OIII]-like ions are known to extendin the kpc range. All together indicates a stratification in the ionized gas, usually interpreted in terms of nuclear photoionization as the driving ionization mechanism. However, CL profiles show various peculiarities: they are broader by a factor of two than lower ionization lines, the broadening being in terms of asymmetric blue wings, and their centroid position at the nucleus is blueshifted by a few hundreds of km/s. Moreover, in NGC1386 a...

  7. Compact molecular disc and ionized gas outflows within 350 pc of the active nucleus of Mrk 1066

    CERN Document Server

    Riffel, Rogemar A

    2010-01-01

    We present stellar and gaseous kinematics of the inner 350 pc radius of the Seyfert galaxy Mrk1066 derived from J and Kl bands data obtained with the Gemini NIFS at a spatial resolution of 35 pc. The stellar velocity field is dominated by rotation in the galaxy plane but shows an S-shape distortion along the galaxy minor axis which seems to be due to an oval structure seen in an optical continuum image. Along this oval, between 170 and 280 pc from the nucleus we find a partial ring of low sigma (~50 km/s) attributed to an intermediate age stellar population. Fro measurements of the emission-line fluxes and profiles ([PII]1.19um, [FeII]1.26um, Pa-beta and H2 2.12um), we have constructed maps for the gas centroid velocity, velocity dispersion, as well as channel maps. The velocity fields for all emission lines are dominated by a similar rotation pattern to that observed for the stars, but are distorted by the presence of two structures: (i) a compact rotating disc with radius r~70 pc; (ii) outflows along the ra...

  8. Protostellar Outflows

    Science.gov (United States)

    Bally, John

    2016-09-01

    Outflows from accreting, rotating, and magnetized systems are ubiquitous. Protostellar outflows can be observed from radio to X-ray wavelengths in the continuum and a multitude of spectral lines that probe a wide range of physical conditions, chemical phases, radial velocities, and proper motions. Wide-field visual and near-IR data, mid-IR observations from space, and aperture synthesis with centimeter- and millimeterwave interferometers are revolutionizing outflow studies. Many outflows originate in multiple systems and clusters. Although most flows are bipolar and some contain highly collimated jets, others are wide-angle winds, and a few are nearly isotropic and exhibit explosive behavior. Morphologies and velocity fields indicate variations in ejection velocity, mass-loss rate, and in some cases, flow orientation and degree of collimation. These trends indicate that stellar accretion is episodic and often occurs in a complex dynamical environment. Outflow power increases with source luminosity but decreases with evolutionary stage. The youngest outflows are small and best traced by molecules such as CO, SiO, H2O, and H2. Older outflows can grow to parsec scales and are best traced by shock-excited atoms and ions such as hydrogen-recombination lines, [Sii], and [Oii]. Outflows inject momentum and energy into their surroundings and provide an important mechanism in the self-regulation of star formation. However, momentum injection rates remain uncertain with estimates providing lower bounds.

  9. Cationic and neutral nitrosamide: Viable molecules in the dilute gas phase

    DEFF Research Database (Denmark)

    Egsgaard, H.; Carlsen, L.; Weiske, T.;

    1992-01-01

    Nitrosamide, NH2NO, has been generated and characterized in the dilute gas phase by means of neutralization reionization mass spectrometry in combination with extensive isotopic labelling. The molecule was found to be stable under these conditions having a minimal lifetime in the microsecond time...

  10. Researches on the Neutral Gas Pressure in the Divertor Chamber of the HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    WANGMingxu; LIBo; YANGZhigang; YANLongwen; HONGWenyu; YUANBaoshan; LIULi; CAOZeng; CUIChenghe; LIUYong; WANGEnyao; ZHANGNianman

    2003-01-01

    The neutral gas pressure in divertor chamber is a very basic and important physics parameter because it determines the temperature of charged particles, the thermal flux density onto divertor plates, the erosion of divertor plates, impurity retaining and exhausting, particle transportation and confinement performance of plasma in tokamaks. Therefore, the pressure measurement in divertor chamber is taken into account in many large tokamaks.

  11. Vortex line in a neutral finite-temperature superfluid Fermi gas

    DEFF Research Database (Denmark)

    Nygaard, Nicolai; Bruun, G. M.; Schneider, B. I.;

    2004-01-01

    The structure of an isolated vortex in a dilute two-component neutral superfluid Fermi gas is studied within the context of self-consistent Bogoliubov-de Gennes theory. Various thermodynamic properties are calculated, and the shift in the critical temperature due to the presence of the vortex...

  12. Numerical investigation of interface region flows in mass spectrometers: neutral gas transport

    Energy Technology Data Exchange (ETDEWEB)

    Jugroot, Manish [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ontario, M3H 5T6 (Canada); Groth, Clinton P T [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ontario, M3H 5T6 (Canada); Thomson, Bruce A [MDS SCIEX, 71 Four Valley Drive, Concord, Ontario, L4K 4V8 (Canada); Baranov, Vladimir [MDS SCIEX, 71 Four Valley Drive, Concord, Ontario, L4K 4V8 (Canada); Collings, Bruce A [MDS SCIEX, 71 Four Valley Drive, Concord, Ontario, L4K 4V8 (Canada)

    2004-04-21

    The supersonic jet flows of neutral gas from atmospheric to near-vacuum conditions in the interface region of mass-spectrometer systems is investigated by continuum-based (fluid) numerical simulations. An enhanced understanding of the neutral gas transport is of paramount importance to fully understand flows in the interface region of mass spectrometers, for it is the neutral dynamics that governs and drives the ions from the high pressure ion source through the interface orifice towards the ion optics and detector subsystems. The key features and structure of the complex neutral gas flow are examined and the influence of large pressure differences imposed across the interface region, orifice geometry, and gas skimmer configuration used for flow control are assessed. The flow structure is shown to be that of a classical under-expanded free jet for 'skimmer-absent' cases and very good agreement between the numerical predictions and empirical and experimental values is demonstrated. For the 'skimmer-present' cases, the shock structure downstream of the orifice and skimmer is identified and fully described and its influences on the flow skimming and focusing processes are discussed.

  13. 3D Simulation of Neutral Gas Dynamics for PVD DC-MSIP and HPPMS Processes

    CERN Document Server

    Bobzin, Kirsten; Mussenbrock, Thomas; Bagcivan, Nazlim; Brugnara, Ricardo Henrique; Schäfer, Marcel; Trieschmann, Jan

    2013-01-01

    Magnetron sputtering processes used for physical vapor deposition often require gas pressures well below 1 Pa. Under these conditions the gas flow in the reactor is usually determined by a Knudsen number of about one, i.e. a transition regime between the hydrodynamic and the rarefied gas regime. In the first, the gas flow is well described by the Navier-Stokes equations, while in the second a kinetic approach via the Boltzmann equation is necessary. In this paper the neutral and reactive gas flow of argon and molecular nitrogen gas inside an industrial scale plasma reactor is simulated using a fluid model, as well as a fully kinetic model. The results are compared and it is found that the gas flow appears to be significantly different, although the neutral particles exhibit a Maxwell-Boltzmann distribution in energy space for both approaches. It is shown that the results are in qualitative agreement and the main expected characteristics of the gas flow are covered by both models. However, only the kinetic mod...

  14. An enhancement of plasma density by neutral gas injection observed in SEPAC Spacelab-1 experiment

    Science.gov (United States)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Kubota, S.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.; Williamson, P. R.

    1985-01-01

    An enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented. When a plume of nitrogen gas was injected from the orbiter into space, a large amount of plasma was detected by an onboard plasma probe. The observed density often increased beyond the background plasma density and was strongly dependent on the attitude of the orbiter with respect to the velocity vector. This effect has been explained by a collisional interaction between the injected gas molecules and the ionospheric ions relatively drifting at the orbital speed.

  15. AGN-enhanced outflows in star-forming galaxies at 1.7gas perspective

    CERN Document Server

    Talia, M; Brusa, M; Lemaux, B C; Amorin, R; Bardelli, S; Cassarà, L P; Cucciati, O; Garilli, B; Grazian, A; Guaita, L; Hathi, N P; Koekemoer, A; Fèvre, O Le; Maccagni, D; Nakajima, K; Pentericci, L; Pforr, J; Schaerer, D; Vanzella, E; Vergani, D; Zamorani, G; Zucca, E

    2016-01-01

    Fast and energetic winds are invoked by galaxy formation models as essential processes in the evolution of galaxies. These massive gas outflows can be powered either by star-formation and/or AGN activity, but the relative dominance of the two mechanisms is still under debate. In this work we use spectroscopic stacking analysis to study the properties of the low-ionization phase of the outflow in a sample of 1332 star-forming galaxies (SFGs) and 62 X-ray detected (L_X < 10^45 erg/s) Type 2 AGN at 1.7outflow up to velocities that could not be reached only with the star-formation contribution. The sample of X-ray AGN has on average a lower SFR than non-AGN SFGs of similar mass: this, combined with the enhanced outflow velocity i...

  16. MOS Mapping of the NIR Outflow HH 223

    Science.gov (United States)

    López, R.; Acosta-Pulido, J. A.; Estalella, R.; Gómez, G.; García-Lorenzo, B.

    2016-10-01

    The Multi-Object-Spectroscopy (MOS) mode of LIRIS was used to map the near-IR stellar outflow HH 223, in the dark cloud Lynds 723 (L723). HH 223 spatially coincides with the east-west component of the L723 quadrupolar CO outflow. The radio continuum source SMA2, towards the center of the quadrupolar CO outflow, hides the YSO that seems to power both the near-IR and the CO outflows. To map the S-shaped, near-IR emission of HH 223, extending ˜ 5', an appropriate mask was designed, with 16 rectangular slitlets. J, H and K-band spectra (R ˜eq 2500) were obtained through the mask. The kinematics of the neutral (H2) and ionized ([FeII]) gas outflow was derived from these data. The results confirm that both the near-IR and the CO outflows have a common driving source. To our knowledge, this is the first use of the MOS-LIRIS observing mode with the mask designed ad hoc to fit several extended, nonaligned targets.

  17. Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein-Cooper, Elijah Z.; Pardy, Stephen A. [Department of Astronomy, University of Wisconsin, 475 N Charter Street, Madison, WI 53706 (United States); Cannon, John M., E-mail: ezbc@astro.wisc.edu, E-mail: spardy@astro.wisc.edu, E-mail: jcannon@macalester.edu [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); and others

    2014-08-01

    We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V {sub c} =15 ± 5 km s{sup –1}. Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s{sup –1} and 10.1 ± 1.2 km s{sup –1}, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

  18. Collision of an Arched Plasma-Filled Flux Rope with a Target Cloud of Initially Neutral Gas

    Science.gov (United States)

    Wongwaitayakornkul, Pakorn; Bellan, Paul M.

    2015-11-01

    The Caltech solar loop experiment apparatus had been used to create an arched plasma-filled flux rope that expands to collide with a pre-injected initially-neutral gas. We investigated such a situation in two regimes: (i) plasma made by heavy gas impacting a much lighter neutral gas cloud and (ii) a light-gas plasma impacting much heavier neutral gas. The neutral gas became ionized immediately upon impact. In regime (i), multiple shock layers were formed in the target cloud; these magnetized collisionless shocks are relevant to solar physics as such shocks develop ahead of Coronal Mass Ejections and occur in Co-rotating Interaction Regions. In regime (ii), plasma expansion was inhibited. In both cases, fast camera images, magnetic probe measurements, and spectroscopy data will be reported. The analysis of plasma and shock expansion, as well as associated density and temperature changes, will be presented.

  19. The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission

    Science.gov (United States)

    Mahaffy, Paul R.; Benna, Mehdi; King, Todd; Harpold, Daniel N.; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carrigan, Daniel; Errigo, Therese; Holmes, Vincent; Kellogg, James; Jaeger, Ferzan; Raaen, Eric; Tan, Florence

    2014-01-01

    The Neutral Gas and Ion Mass Spectrometer (NGIMS) of the Mars Atmosphere and Volatile Evolution Mission (MAVEN) is designed to measure the composition, structure, and variability of the upper atmosphere of Mars. The NGIMS complements two other instrument packages on the MAVEN spacecraft designed to characterize the neutral upper atmosphere and ionosphere of Mars and the solar wind input to this region of the atmosphere. The combined measurement set is designed to quantify atmosphere escape rates and provide input to models of the evolution of the martian atmosphere. The NGIMS is designed to measure both surface reactive and inert neutral species and ambient ions along the spacecraft track over the 125-500 km altitude region utilizing a dual ion source and a quadrupole analyzer.

  20. Asymptotic theory of neutral stability curve of the Couette flow of vibrationally excited gas

    Science.gov (United States)

    Grigor'ev, Yu N.; Ershov, I. V.

    2016-06-01

    The asymptotic theory of neutral stability curve of the supersonic plane Couette flow of vibrationally excited gas is constructed. The system of two-temperature viscous gas dynamics equations was used as original mathematical model. Spectral problem for an eighth order linear system of ordinary differential equations was obtained from the system within framework of classical theory of linear stability. Transformations of the spectral problem universal for all shear flows were carried along the classical Dunn — Lin scheme. As a result the problem was reduced to secular algebraic equation with a characteristic division on “inviscid” and “viscous” parts which was solved numerically. The calculated neutral stability curves coincide in limits of 10% with corresponding results of direct numerical solution of original spectral problem.

  1. Kinematic Constraints on Evolutionary Scenarios for Blue Compact Dwarf Galaxies I. Neutral Gas Dynamics

    CERN Document Server

    Van Zee, L; Skillman, E D; Zee, Liese van; Salzer, John J.; Skillman, Evan D.

    2001-01-01

    We present the results of high spatial resolution HI synthesis observations of six blue compact dwarf (BCD) galaxies. Optically, the selected galaxies have smooth, symmetric isophotes, and thus are the most likely of the BCD class to fade into an object morphologically similar to a dwarf elliptical when the current starburst ends. The neutral gas in all six galaxies appears to be rotationally supported, however, indicating that true morphological transformation from a BCD to a dE will require significant loss of angular momentum. Based on the observed neutral gas dynamics of these and other BCDs, it is unlikely that present-day BCDs will evolve directly into dwarf ellipticals after a starburst phase. We discuss alternative evolutionary scenarios for BCDs and place them within the larger context of galaxy formation and evolution models.

  2. ALFALFA Discovery of the Nearby Gas-rich Dwarf Galaxy Leo P. V. Neutral Gas Dynamics and Kinematics

    CERN Document Server

    Bernstein-Cooper, Elijah Z; Elson, Edward C; Warren, Steven R; Chengalur, Jayaram; Skillman, Evan D; Adams, Elizabeth A K; Bolatto, Alberto D; Giovanelli, Riccardo; Haynes, Martha P; McQuinn, Kristen B W; Pardy, Stephen A; Rhode, Katherine L; Salzer, John J

    2014-01-01

    We present new HI spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our HI images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The HI morphology is slightly elongated along the optical major-axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V_c = 15 +/- 5 km/s. Within the HI radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ~15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature ...

  3. The interaction between the solar wind and the heterogeneous neutral gas coma of comet 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Rubin, Martin; Toth, Gabor; Tenishev, Valeriy; Fougere, Nicolas; Huang, Zhenguang

    2016-07-01

    Comets are surrounded by an extended gas and dust coma. Neutral particles are continuously ionized by solar irradiation and then picked-up by the solar wind. This leads to a complex interaction between the neutral gas coma and the solar wind, which changes over the course of the comet's orbit around the Sun. The European Space Agency's Rosetta spacecraft has been in orbit around comet 67P/Churyumov-Gerasimenko since August 2014. Rosetta carries several instruments to investigate the comet's nucleus and surrounding neutral gas coma and plasma. Part of the payload is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) that consists of two mass spectrometers and a pressure sensor. ROSINA was designed to measure the neutral gas abundance and composition and low energy ions in the coma in situ. ROSINA observations have shown that the coma is very heterogeneous both in total density and composition of the neutral gas. This heterogeneity is driven in large part by the complex shape of the nucleus and the varying illumination conditions associated with the comet's rotation. In this presentation we will show the time-dependent distribution of the major volatiles around the comet constrained by ROSINA observations. Furthermore we will investigate the impact of the highly non-symmetric neutral gas coma on the interaction of the solar wind with the comet.

  4. The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHα 198 and LkHα 225S

    Science.gov (United States)

    Matthews, Brenda C.; Graham, James R.; Perrin, Marshall D.; Kalas, Paul

    2007-12-01

    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity, and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHα 198 and LkHα 225S. Single-dish observations of 12CO J=1-0, 13CO J=1-0, N2H+ J=1-0, and CS J=2-1 were made over a field of 4.3'×4.3' for each species. 12CO J=1-0 data from FCRAO were combined with high-resolution BIMA array data to achieve a naturally weighted synthesized beam of 6.75''×5.5'' toward LkHα 198 and 5.7''×3.95'' toward LkHα 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of 2 improvement. The outflow around LkHα 198 resolves into at least four outflows, none of which are centered on LkHα 198-IR, but even at our resolution we cannot exclude the possibility of an outflow associated with this source. In the LkHα 225S region we find evidence for two outflows associated with LkHα 225S itself, and a third outflow is likely driven by this source. Identification of the driving sources is still resolution limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO J=1-0 is present in the environments of both stars along with cold, dense gas as traced by CS J=2-1 and (in LkHα 225S) N2H+ J=1-0. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.

  5. Another piece of the puzzle: the fast HI outflow in Mrk231

    CERN Document Server

    Morganti, Raffaella; Oosterloo, Tom; Teng, Stacy H; Rupke, David

    2016-01-01

    We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast HI 21-cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow HI absorption blueshifted ~1300 km/s with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15x10^18 Tspin cm^-2. We derive the Tspin to lie in the range 400-2000 K and the densities are n_HI~10-100 cm^-3. Our results confirm the multiphase nature of the outflow in Mrk231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the HI outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by NaI and molecular gas. Our results suggest that an HI component is present in fast outflows regard...

  6. Complete Ionisation of the Neutral Gas in High Redshift Radio Galaxies and Quasars

    CERN Document Server

    Curran, S J

    2012-01-01

    Cool neutral gas provides the raw material for all star formation in the Universe, and yet, from a survey of the hosts of high redshift radio galaxies and quasars, we find a complete dearth of atomic (HI 21-cm) and molecular (OH, CO, HCO+ & HCN) absorption at redshifts z > 3. Upon a thorough analysis of the optical photometry, we find that all of our targets have ionising ultra-violet continuum luminosities of logL > 23 W/Hz. We therefore attribute this deficit to the traditional optical selection of targets biasing surveys towards the most ultra-violet luminous objects, where the intense radiation excites the neutral gas to the point where it cannot engage in star formation. However, this hypothesis does not explain why there is a critical luminosity, rather than a continuum where the detections gradually become fewer and fewer as the harshness of the radiation increases. We show that by placing a quasar within a galaxy of gas there is always a finite ultra-violet luminosity above which all of the gas is...

  7. Effects of additional vapors on sterilization of microorganism spores with plasma-excited neutral gas

    Science.gov (United States)

    Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

    2015-01-01

    Some fundamental experiments are carried out in order to develop a plasma process that will uniformly sterilize both the space and inner wall of the reactor chamber at atmospheric pressure. Air, oxygen, argon, and nitrogen are each used as the plasma source gas to which mixed vapors of water and ethanol at different ratios are added. The reactor chamber is remotely located from the plasma area and a metal mesh for eliminating charged particles is installed between them. Thus, only reactive neutral particles such as plasma-excited gas molecules and radicals are utilized. As a result, adding vapors to the source gas markedly enhances the sterilization effect. In particular, air with water and/or ethanol vapor and oxygen with ethanol vapor show more than 6-log reduction for Geobacillus stearothermophilus spores.

  8. Metallicity and Quasar Outflows

    CERN Document Server

    Wang, Huiyuan; Yuan, Weimin; Wang, Tinggui

    2012-01-01

    Correlations are investigated of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the CIV line (Wang et al. 2011), with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey. We find that most of the line ratios of other ions to CIV prominently increases with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of dominant coolant, CIV line, decreases and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using SiIV+OIV]/CIV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicitiy and the outflow strength of quasars over a wide range of 1.7 to 6.9 times solar abundance. Our result implies that the metallicity plays an important role in the formation of quasar outflows, likely via affecting outflow acceleration. This ...

  9. Asymptotic theory of neutral stability of the Couette flow of a vibrationally excited gas

    Science.gov (United States)

    Grigor'ev, Yu. N.; Ershov, I. V.

    2017-01-01

    An asymptotic theory of the neutral stability curve for a supersonic plane Couette flow of a vibrationally excited gas is developed. The initial mathematical model consists of equations of two-temperature viscous gas dynamics, which are used to derive a spectral problem for a linear system of eighth-order ordinary differential equations within the framework of the classical linear stability theory. Unified transformations of the system for all shear flows are performed in accordance with the classical Lin scheme. The problem is reduced to an algebraic secular equation with separation into the "inviscid" and "viscous" parts, which is solved numerically. It is shown that the thus-calculated neutral stability curves agree well with the previously obtained results of the direct numerical solution of the original spectral problem. In particular, the critical Reynolds number increases with excitation enhancement, and the neutral stability curve is shifted toward the domain of higher wave numbers. This is also confirmed by means of solving an asymptotic equation for the critical Reynolds number at the Mach number M ≤ 4.

  10. DLA kinematics and outflows from starburst galaxies

    CERN Document Server

    Razoumov, Alexei O

    2008-01-01

    We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses...

  11. Electrostatic plasma instabilities driven by neutral gas flows in the solar chromosphere

    CERN Document Server

    Gogoberidze, G; Poedts, S; De Keyser, J

    2013-01-01

    We investigate electrostatic plasma instabilities of Farley-Buneman (FB) type driven by quasi-stationary neutral gas flows in the solar chromosphere. The role of these instabilities in the chromosphere is clarified. We find that the destabilizing ion thermal effect is highly reduced by the Coulomb collisions and can be ignored for the chromospheric FB-type instabilities. On the contrary, the destabilizing electron thermal effect is important and causes a significant reduction of the neutral drag velocity triggering the instability. The resulting threshold velocity is found as function of chromospheric height. Our results indicate that the FB type instabilities are still less efficient in the global chromospheric heating than the Joule dissipation of the currents driving these instabilities. This conclusion does not exclude the possibility that the FB type instabilities develop in the places where the cross-field currents overcome the threshold value and contribute to the heating locally. Typical length-scales...

  12. A Pre-ionization System to Limit Neutral Gas in a Compact Toroid Injector

    Science.gov (United States)

    Allfrey, Ian; Roche, Thomas; Matsumoto, Tadafumi; Garate, Eusebio; Gota, Hiroshi; Asai, Tomohiko; the TAE Team

    2016-10-01

    Fusion plasmas require long lifetimes and high temperatures, both of which are limited by particle loss, among other factors. Therefore, refueling a long-lived advanced beam-driven field-reversed configuration (FRC) plasma in C-2U is necessary, and injecting a supersonic compact toroid (CT) is an effective means of introducing particles into the FRC core. However, neutral gas that trails the CT into the target chamber cools the FRC. Pre-ionization (PI) system assists the break down between electrodes of the CT injector (CTI), so the amount of introduced gas can be lowered by up to a factor of two, effectively increasing the ionization fraction; thus, reducing the amount of neutral gas in the system. Additionally, the PI decreases the delay in CTI breakdown so a highly reproducible operation is achievable. The PI system consists of a fast, high voltage, pulse discharge circuit coupled to a Teflon insulated semi-rigid coaxial cable inserted into the CTI. System details and experimental data will be presented, in addition to issues such as the introduction of impurities and pre-ionizer lifetime.

  13. Air-sea exchange and gas-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow.

    Science.gov (United States)

    Wu, Zilan; Lin, Tian; Li, Zhongxia; Jiang, Yuqing; Li, Yuanyuan; Yao, Xiaohong; Gao, Huiwang; Guo, Zhigang

    2017-11-01

    We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea gas exchange, and gas-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea exchange fluxes of gaseous PAHs were estimated to be -54.2-107.4 ng m(-2) d(-1), and was indicative of variations of land-based PAH inputs. The logarithmic gas-particle partition coefficient (logKp) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (logPL(0)), with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH gas-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH gas-particle partitioning deviated more from the modeling Kp for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea exchange. Meanwhile, significant linear regressions between logKp and logKoa (logKsa) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Outflow forces in intermediate mass star formation

    CERN Document Server

    van Kempen, T A; van Dishoeck, E F; Kristensen, L E; Belloche, A; Klaassen, P D; Leurini, S; Jose-Garcia, I San; Aykutalp, A; Choi, Y; Endo, A; Frieswijk, W; Harsono, D; Karska, A; Koumpia, E; van der Marel, N; Nagy, Z; Perez-Beaupuits, J P; Risacher, C; van Weeren, R J; Wyrowski, F; Yildiz, U A; Guesten, R; Boland, W; Baryshev, A

    2015-01-01

    Intermediate mass protostarsprovide a bridge between theories of low- and high-mass star formation. Emerging molecular outflows can be used to determine the influence of fragmentation and multiplicity on protostellar evolution through the correlation of outflow forces of intermediate mass protostars with the luminosity. The aim of this paper is to derive outflow forces from outflows of six intermediate mass protostellar regions and validate the apparent correlation between total luminosity and outflow force seen in earlier work, as well as remove uncertainties caused by different methodology. By comparing CO 6--5 observations obtained with APEX with non-LTE radiative transfer model predictions, optical depths, temperatures, densities of the gas of the molecular outflows are derived. Outflow forces, dynamical timescales and kinetic luminosities are subsequently calculated. Outflow parameters, including the forces, were derived for all sources. Temperatures in excess of 50 K were found for all flows, in line wi...

  15. On the neutral gas content of nine new Milky Way satellite galaxy candidates

    CERN Document Server

    Westmeier, T; Calabretta, M; Jurek, R; Koribalski, B S; Meyer, M; Popping, A; Wong, O I

    2015-01-01

    We use a new, improved version of the HI Parkes All-Sky Survey to search for HI emission from nine new, ultra-faint Milky Way satellite galaxy candidates recently discovered in data from the Dark Energy Survey. None of the candidates is detected in HI, implying upper limits for their HI masses of typically several hundred to a few thousand solar masses. The resulting upper limits on M_HI / L_V and M_HI / M_star suggest that at least some of the new galaxy candidates are HI deficient. This finding is consistent with the general HI deficiency of satellite galaxies located within the Milky Way's virial radius and supports the hypothesis that gas is being removed from satellites by tidal and ram-pressure forces during perigalactic passages. In addition, some of the objects may be embedded in, and interacting with, the extended neutral and ionised gas filaments of the Magellanic Stream.

  16. Infrared Action Spectroscopy of Low-Temperature Neutral Gas-Phase Molecules of Arbitrary Structure

    Science.gov (United States)

    Yatsyna, Vasyl; Bakker, Daniël J.; Salén, Peter; Feifel, Raimund; Rijs, Anouk M.; Zhaunerchyk, Vitali

    2016-09-01

    We demonstrate a technique for IR action spectroscopy that enables measuring IR spectra in a background-free fashion for low-temperature neutral gas-phase molecules of arbitrary structure. The method is exemplified experimentally for N -methylacetamide molecules in the mid-IR spectral range of 1000 - 1800 cm-1 , utilizing the free electron laser FELIX. The technique involves the resonant absorption of multiple mid-IR photons, which induces molecular dissociation. The dissociation products are probed with 10.49 eV vacuum ultraviolet photons and analyzed with a mass spectrometer. We also demonstrate the capability of this method to record, with unprecedented ease, mid-IR spectra for the molecular associates, such as clusters and oligomers, present in a molecular beam. In this way the mass-selected spectra of low-temperature gas-phase dimers and trimers of N -methylacetamide are measured in the full amide I-III range.

  17. Using IBEX data to constrain the heliosphere's large-scale structure: interstellar neutral gas and the Warm Breeze

    Science.gov (United States)

    Bzowski, Maciej; McComas, David; Galli, Andre; Kucharek, Harald; Wurz, Peter; Sokol, Justyna M.; Schwadron, Nathan; Heirtzler, David M.; Kubiak, M. Marzena A.; Möbius, Eberhard; Fuselier, Stephen; Swaczyna, Paweł; Leonard, Trevor; Park, Jeewoo

    2016-07-01

    The large-scale structure of the heliosphere is governed by the interaction of the partly ionized, magnetized interstellar gas and the magnetized, fully ionized solar wind, structured in heliolatitude. Determining factors of this interaction are the density and flow velocity of interstellar gas relative to the Sun, the Mach number of this flow and the strength and inclination of the interstellar magnetic field to the flow vector at the interstellar side, and the magnitude of dynamic pressure of solar wind and the strength of its embedded magnetic field at the solar side. As a result of charge exchange interactions operating in the boundary region between the heliosphere and interstellar matter, a new population of neutral atoms is created, in addition to the population of unperturbed interstellar neutral gas. Both of these populations penetrate deep inside the heliosphere, where they can be sampled by the first space probe dedicated to observations of the heliosphere and its immediate surroundings by means of neutral atoms: the Interstellar Boundary Explorer (IBEX). Due to distortion of the heliosphere from axial symmetry, the secondary population of interstellar neutrals, created via charge exchange between the plasma flowing past the heliopause and the unperturbed pristine neutral interstellar gas, appears to be coming from a different direction than the unperturbed interstellar neutral flow. These two directions should be coplanar with the plane defined by the local interstellar magnetic field and the flow direction of the unperturbed gas. IBEX provides an unprecedented opportunity to study and interpret these relations. The IBEX science team have recently accomplished important milestones in researching the primary and secondary populations of interstellar gas and their relation to the local interstellar magnetic fields. First, the temperature and velocity vector of the inflowing interstellar neutral gas has been determined with unprecedented robustness based

  18. Developing QSPR model of gas/particle partition coefficients of neutral poly-/perfluoroalkyl substances

    Science.gov (United States)

    Yuan, Quan; Ma, Guangcai; Xu, Ting; Serge, Bakire; Yu, Haiying; Chen, Jianrong; Lin, Hongjun

    2016-10-01

    Poly-/perfluoroalkyl substances (PFASs) are a class of synthetic fluorinated organic substances that raise increasing concern because of their environmental persistence, bioaccumulation and widespread presence in various environment media and organisms. PFASs can be released into the atmosphere through both direct and indirect sources, and the gas/particle partition coefficient (KP) is an important parameter that helps us to understand their atmospheric behavior. In this study, we developed a temperature-dependent predictive model for log KP of PFASs and analyzed the molecular mechanism that governs their partitioning equilibrium between gas phase and particle phase. All theoretical computation was carried out at B3LYP/6-31G (d, p) level based on neutral molecular structures by Gaussian 09 program package. The regression model has a good statistical performance and robustness. The application domain has also been defined according to OECD guidance. The mechanism analysis shows that electrostatic interaction and dispersion interaction play the most important role in the partitioning equilibrium. The developed model can be used to predict log KP values of neutral fluorotelomer alcohols and perfluor sulfonamides/sulfonamidoethanols with different substitutions at nitrogen atoms, providing basic data for their ecological risk assessment.

  19. Dense gas and exciting sources of the molecular outflow in the AFGL 437 star-forming region

    CERN Document Server

    Manjarrez, G; de Gregorio-Monsalvo, I

    2011-01-01

    We present Very Large Array (VLA) high resolution observations of the NH3(1,1) and NH3(2,2) molecular transitions towards the high mass star forming region AFGL 437. Our aim was to investigate if the poorly collimated CO molecular outflow previously detected in the region is the result of a projection effect, with no intrinsic bipolarity, as suggested by Gomez et al. We complemented our observations with radio continuum archived data from the VLA at 2 and 3.6 cm, and with unpublished public data at 450 {\\mu}m taken with Submillimetre Common-User Bolometer Array at the James Clerk Maxwell Telescope. Ammonia emission was found mainly in three clumps located at the south and east of the position of the compact infrared cluster of AFGL 437, where the CO outflow seemed to have its origin. One of the NH3(1,1) clumps coincides with the maximum of NH3(2,2) and with a local peak of emission at 450 {\\mu}m. A near infrared source (s11) is also found at that position. Our continuum map at 2 cm shows extended elongated em...

  20. Observing the Interstellar Neutral He Gas Flow with a Variable IBEX Pointing Strategy

    Science.gov (United States)

    Leonard, T.; Moebius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; McComas, D. J.; Schwadron, N.; Wurz, P.

    2015-12-01

    The Interstellar Neutral (ISN) gas flow can be observed at Earth's orbit due to the motion of the solar system relative to the surrounding interstellar gas. Since He is minimally influenced by ionization and charge exchange, the ISN He flow provides a sample of the pristine interstellar environment. The Interstellar Boundary Explorer (IBEX) has observed the ISN gas flow over the past 7 years from a highly elliptical orbit around the Earth. IBEX is a Sun-pointing spinning spacecraft with energetic neutral atom (ENA) detectors observing perpendicular to the spacecraft spin axis. Due to the Earth's orbital motion around the Sun, it is necessary for IBEX to perform spin axis pointing maneuvers every few days to maintain a sunward pointed spin axis. The IBEX operations team has successfully pointed the spin axis in a variety of latitude orientations during the mission, including in the ecliptic during the 2012 and 2013 seasons, about 5 degrees below the ecliptic during the 2014 season, and recently about 5 degrees above the ecliptic during the 2015 season, as well as optimizing observations with the spin axis pointed along the Earth-Sun line. These observations include a growing number of measurements near the perihelion of the interstellar atom trajectories, which allow for an improved determination of the ISN He bulk flow longitude at Earth orbit. Combining these bulk flow measurements with an analytical model (Lee et al. 2012 ApJS, 198, 10) based upon orbital mechanics improves the knowledge of the narrow ISN parameter tube, obtained with IBEX, which couples the interstellar inflow longitude, latitude, speed, and temperature.

  1. Charge transfer reactions at interfaces between neutral gas and plasma: Dynamical effects and X-ray emission

    Science.gov (United States)

    Provornikova, E.; Izmodenov, V. V.; Lallement, R.

    2012-04-01

    Charge-transfer is the main process linking neutrals and charged particles in the interaction regions of neutral (or partly ionized) gas with a plasma. In this paper we illustrate the importance of charge-transfer with respect to the dynamics and the structure of neutral gas-plasma interfaces. We consider the following phenomena: (1) the heliospheric interface - region where the solar wind plasma interacts with the partly-ionized local interstellar medium (LISM) and (2) neutral interstellar clouds embedded in a hot, tenuous plasma such as the million degree gas that fills the so-called ``Local Bubble". In (1), we discuss several effects in the outer heliosphere caused by charge exchange of interstellar neutral atoms and plasma protons. In (2) we describe the role of charge exchange in the formation of a transition region between the cloud and the surrounding plasma based on a two-component model of the cloud-plasma interaction. In the model the cloud consists of relatively cold and dense atomic hydrogen gas, surrounded by hot, low density, fully ionized plasma. We discuss the structure of the cloud-plasma interface and the effect of charge exchange on the lifetime of interstellar clouds. Charge transfer between neutral atoms and minor ions in the plasma produces X-ray emission. Assuming standard abundances of minor ions in the hot gas surrounding the cold interstellar cloud, we estimate the X-ray emissivity consecutive to the charge transfer reactions. Our model shows that the charge-transfer X-ray emission from the neutral cloud-plasma interface may be comparable to the diffuse thermal X-ray emission from the million degree gas cavity itself.

  2. Four-fluid MHD Simulations of the Plasma and Neutral Gas Environment of Comet Churyumov-Gerasimenko Near Perihelio

    Science.gov (United States)

    Huang, Z.; Toth, G.; Gombosi, T. I.; Jia, X.; Rubin, M.; Hansen, K. C.; Fougere, N.; Bieler, A. M.; Shou, Y.; Altwegg, K.; Combi, M. R.; Tenishev, V.

    2015-12-01

    The neutral and plasma environment is critical in understanding the interaction of comet Churyumov-Gerasimenko (CG), the target of the Rosetta mission, and the solar wind. To serve this need and support the Rosetta mission, we develop a 3-D four fluid model, which is based on BATS-R-US within the SWMF (Space Weather Modeling Framework) that solves the governing multi-fluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. This model incorporates different mass loading processes, including photo and electron impact ionization, charge exchange, dissociative ion-electron recombination, and collisional interactions between different fluids. We simulate the near nucleus plasma and neutral gas environment near perihelion with a realistic shape model of CG and compare our simulation results with Rosetta observations.

  3. Effects of neutral gas release on current collection during the CHARGE-2 rocket experiment

    Science.gov (United States)

    Gilchrist, B. E.; Banks, P. M.; Neubert, T.; Williamson, P. R.; Myers, Neil B.; Raitt, W. John; Sasaki, S.

    1990-01-01

    Observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged rocket payload in the ionosphere are reported. These observations were made during the second cooperative high altitude rocket gun experiment (CHARGE-2) which was an electrically tethered mother/daughter payload system. The current collection enhancement was observed at the daughter payload located 100 to 400 m away from the mother which was firing an energetic electron beam. The authors interpret these results in terms of an electrical discharge forming in close proximity to the daughter during the short periods of gas emission. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an otherwise undisturbed space plasma. These results can also be compared with recent laboratory observations of hollow cathode plasma contactors operating in the ignited mode. Experimental observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged, isolated daughter payload in the nighttime ionosphere were made. These observations were derived from the second cooperative high altitude rocket gun experiment (CHARGE-2) which was an electrically tethered mother-daughter payload system. The rocket flew from White Sands Missile Range (WSMR) in December, 1985. The rocket achieved an altitude of 261 km and carried a 1 keV electron beam emitting up to 48 mA of current (Myers, et al., 1989a). The mother payload, carried the electron beam source, while the daughter acted as a remote current collection and observation platform and reached a distance of 426 m away from the main payload. Gas emissions at the daughter were due to periodic thruster jet firings to maintain separation velocity between the two payloads.

  4. Far-Ir Spectroscopy of Neutral Gas Phase Peptides: Signatures from Combined Experiments and Simulations

    Science.gov (United States)

    Mahé, Jérôme; Gaigeot, Marie-Pierre; Bakker, Daniël; Jaeqx, Sander; Rijs, Anouk

    2016-06-01

    Within the past two decades, action vibrational spectroscopy has become an almost routine experimental method to probe the structures of molecules and clusters in the gas phase (neutral and ions). Such experiments are mainly performed in the 1000-4000 wn fingerprint regions. Though successful in many respects, these spectral domains can be however restrictive in the information provided, and sometimes reach limitations for unravelling structures without ambiguity. In a collaborative work with the group of Dr A.M. Rijs (FELIX laboratory, Radbout University, The Netherlands) we have launched a new strategy where the far-IR/Tera-Hertz domain (100-800 wn domain) is experimentally probed for neutral gas phase molecules. Our group in Paris apply finite temperature DFT-based molecular dynamics (DFT-MD) simulations in order to unravel the complex signatures arising in the far-IR domain, and provide an unambiguous assignment both of the structural conformation of the gas phase molecules (taking into account the experimental conditions) and an understanding of the spectral signatures/fingerprints. We will discuss our experimental and theoretical investigations on two neutral peptides in the 100-800 wn far-IR spectral domain, i.e. Z-Ala6 and PheGly dipeptide, that represent two systems which definitive conformational assignment was not possible without the far IR signatures. We will also present our very recent results on the Phe-X peptide series, where X stands for Gly, Ala, Pro, Val, Ser, Cys, combining experiments and DFT-MD simulations, providing a detailed understanding of the vibrational fingerprints in the far-IR domain. In all exemples, we will show how DFT-MD simulations is the proper theoretical tool to account for vibrational anharmonicities and mode couplings, of prime importance in the far-IR domain. References : J. Mahé, S. Jaeqx, A.M. Rijs, M.P. Gaigeot, Phys. Chem. Chem. Phys., 17 :25905 (2015) S. Jaeqx, J. Oomens, A. Cimas, M.P. Gaigeot, A.M. Rijs, Angew

  5. Outflow from Hot Accretion Flows

    CERN Document Server

    Yuan, Feng; Wu, Maochun

    2012-01-01

    Numerical simulations of hot accretion flows have shown that the mass accretion rate decreases with decreasing radius. Two models have been proposed to explain this result. In the adiabatic inflow-outflow solution (ADIOS), it is thought to be due to the loss of gas in outflows. In the convection-dominated accretion flow (CDAF) model, it is explained as because that the gas is locked in convective eddies. In this paper we use hydrodynamical (HD) and magnetohydrodynamical (MHD) simulations to investigate which one is physical. We calculate and compare various properties of inflow (gas with an inward velocity) and outflow (gas with an outward velocity). Systematic and significant differences are found. For example, for HD flows, the temperature of outflow is higher than inflow; while for MHD flows, the specific angular momentum of outflow is much higher than inflow. We have also analyzed the convective stability of MHD accretion flow and found that they are stable. These results suggest that systematic inward an...

  6. SWAS Observations of Water in Molecular Outflows

    CERN Document Server

    Franklin, J; Kaufman, M J; Melnick, G J; Neufeld, D A; Hollenbach, D J; Bergin, E A

    2007-01-01

    We present SWAS detections of the ground-state 1(10)-1(01) transition of o-H2O at 557 GHz in 18 molecular outflows. These results are combined with ground-based observations of the J=1-0 transitions of 12CO and 13CO obtained at the FCRAO and, for a subset of the outflows, data from ISO. Assuming the SWAS water line emission originates from the same gas traced by CO emission, we find that the outflowing gas in most outflows has an o-H2O abundance relative to H2 of between 10(-7) and 10(-6). Analysis of the water abundance as a function of outflow velocity reveals a strong dependence. The water abundance increases with velocity, and at the highest outflow velocities some outflows have relative o-H2O abundances of order 10(-4). However the mass of gas with such elevated water abundances represents less that 1% of the total outflow gas mass. The ISO LWS observations of high-J rotational lines of CO and the 179.5 micron transition of o-H2O provide evidence for a warmer outflow component than required to produce ei...

  7. Integral Field Spectroscopy of Massive, Kiloparsec-Scale Outflows in the Infrared-Luminous QSO Mrk 231

    CERN Document Server

    Rupke, David S N; 10.1088/2041-8205/729/2/L27

    2011-01-01

    The quasi-stellar object (QSO)/merger Mrk 231 is arguably the nearest and best laboratory for studying QSO feedback. It hosts several outflows, including broad-line winds, radio jets, and a poorly-understood kpc scale outflow. In this Letter, we present integral field spectroscopy from the Gemini telescope that represents the first unambiguous detection of a wide-angle, kpc scale outflow from a powerful QSO. Using neutral gas absorption, we show that the nuclear region hosts an outflow with blueshifted velocities reaching 1100 km/s, extending 2-3 kpc from the nucleus in all directions in the plane of the sky. A radio jet impacts the outflow north of the nucleus, accelerating it to even higher velocities (up to 1400 km/s). Finally, 3.5 kpc south of the nucleus, star formation is simultaneously powering an outflow that reaches more modest velocities of only 570 km/s. Blueshifted ionized gas is also detected around the nucleus at lower velocities and smaller scales. The mass and energy flux from the outflow are ...

  8. Spatial distribution of interstellar dust in the Sun's vicinity. Comparison with neutral sodium-bearing gas

    Science.gov (United States)

    Vergely, J.-L.; Valette, B.; Lallement, R.; Raimond, S.

    2010-07-01

    Aims: 3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the interstellar medium itself to foreground decontamination of the cosmic microwave background, or various studies of the environments of specific objects. However, while spectral data cubes of the galactic emission become increasingly precise, the information on the distance to the emitting regions has not progressed as well and relies essentially on the galactic rotation curve. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. Methods: We apply the best available calibration methods to a carefully screened set of stellar Strömgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion, optimized for this specific data set. We apply the same inversion technique to a totally independent set of neutral sodium absorption data available for about 1700 target stars. Results: We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds within 250 pc and identify in those maps well-known dark clouds and high galactic more diffuse entities. We calculate the integrated extinction between the Sun and the cube boundary and compare this with the total galactic extinction derived from infrared 2D maps. The two quantities reach similar values at high latitudes, as expected if the local dust content is satisfyingly reproduced and the dust is closer than 250 pc. Those maps show a larger high latitude dust opacity in the North compared to the South, reinforcing earlier evidences. Interestingly the gas maps do not show the same asymmetry, suggesting a polar asymmetry of the dust to gas

  9. Herschel Far-Infrared Spectral-mapping of Orion BN/KL Outflows: Spatial distribution of excited CO, H2O, OH, O and C+ in shocked gas

    CERN Document Server

    Goicoechea, Javier R; Cernicharo, Jose; Neufeld, David A; Vavrek, Roland; Bergin, Edwin A; Cuadrado, Sara; Encrenaz, Pierre; Etxaluze, Mireya; Melnick, Gary J; Polehampton, Edward

    2014-01-01

    We present ~2'x2' spectral-maps of Orion BN/KL outflows taken with Herschel at ~12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H2 shocked regions "Peak 1" and "Peak 2" from that of the Hot Core and ambient cloud. We analyze the ~54-310um spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of 12CO (up to J=48-47), H2O, OH, 13CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L(FIR)~5x10^{-3} ratio and a plethora of far-IR H2O emission lines. The high-J CO and OH lines are a factor ~2 brighter toward Peak 1 whereas several excited H2O lines are ~50% brighter toward Peak 2. A simplified non-LTE model allowed us to constrain the dominant gas temperature components. Most of the CO column density arises from Tk~200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H2O/CO~10^{-2} abundance r...

  10. The complex, dusty narrow-line region of NGC 4388: Gas-jet interactions, outflows, and extinction revealed by near-IR spectroscopy

    CERN Document Server

    Rodriguez-Ardila, A; Martins, L; Almeida, C Ramos; Riffel, R A; Riffel, R; Lira, P; Martin, O Gonzalez; Dametto, N Z; Flohic, H; Ho, L C; Ruschel-Dutra, D; Thanjavur, K; Colina, L; McDermid, R M; Perlman, E; Winge, C

    2016-01-01

    We present Gemini/GNIRS spectroscopy of the Seyfert 2 galaxy NGC 4388, with simultaneous coverage from 0.85 - 2.5 $\\mu$m. Several spatially-extended emission lines are detected for the first time, both in the obscured and unobscured portion of the optical narrow line region (NLR), allowing us to assess the combined effects of the central continuum source, outflowing gas and shocks generated by the radio jet on the central 280 pc gas. The HI and [FeII] lines allow us to map the extinction affecting the NLR. We found that the nuclear region is heavily obscured, with E(B-V) ~1.9 mag. To the NE of the nucleus and up to ~150 pc, the extinction remains large, ~1 mag or larger, consistent with the system of dust lanes seen in optical imaging. We derived position-velocity diagrams for the most prominent lines as well as for the stellar component. Only the molecular gas and the stellar component display a well-organized pattern consistent with disk rotation. Other emission lines are kinematically perturbed or show lit...

  11. Molecular line emission in NGC 1068 imaged with ALMA : I. An AGN-driven outflow in the dense molecular gas

    NARCIS (Netherlands)

    García-Burillo, S.; Combes, F.; Usero, A.; Aalto, S.; Krips, M.; Viti, S.; Alonso-Herrero, A.; Hunt, L. K.; Schinnerer, E.; Baker, A. J.; Boone, F.; Casasola, V.; Colina, L.; Costagliola, F.; Eckart, A.; Fuente, A.; Henkel, C.; Labiano, A.; Martín, S.; Márquez, I.; Muller, S.; Planesas, P.; Ramos Almeida, C.; Spaans, M.; Tacconi, L. J.; van der Werf, P. P.

    2014-01-01

    Aims: We investigate the fueling and the feedback of star formation and nuclear activity in NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We aim to understand if and how gas accretion can self-regulate. Methods

  12. Molecular line emission in NGC 1068 imaged with ALMA. I. An AGN-driven outflow in the dense molecular gas

    NARCIS (Netherlands)

    García-Burillo, S.; Combes, F.; Usero, A.; Aalto, S.; Krips, M.; Viti, S.; Alonso-Herrero, A.; Hunt, L. K.; Schinnerer, E.; Baker, A. J.; Boone, F.; Casasola, V.; Colina, L.; Costagliola, F.; Eckart, A.; Fuente, A.; Henkel, C.; Labiano, A.; Martín, S.; Márquez, I.; Muller, S.; Planesas, P.; Ramos Almeida, C.; Spaans, M.; Tacconi, L. J.; van der Werf, P. P.

    2014-01-01

    Aims: We investigate the fueling and the feedback of star formation and nuclear activity in NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We aim to understand if and how gas accretion can self-regulate. Methods

  13. HST/COS SPECTRA OF THREE QSOs THAT PROBE THE CIRCUMGALACTIC MEDIUM OF A SINGLE SPIRAL GALAXY: EVIDENCE FOR GAS RECYCLING AND OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Keeney, Brian A.; Stocke, John T.; Danforth, Charles W.; Shull, J. Michael; Green, James C. [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Rosenberg, Jessica L. [Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030 (United States); Ryan-Weber, Emma V. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Mail H30, P.O. Box 218, Hawthorn, 3122 VIC (Australia); Savage, Blair D., E-mail: brian.keeney@colorado.edu [Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling Hall, 475 North Charter Street, Madison, WI 53706 (United States)

    2013-03-01

    We have used the Cosmic Origins Spectrograph (COS) to obtain far-UV spectra of three closely spaced QSO sight lines that probe the circumgalactic medium (CGM) of an edge-on spiral galaxy, ESO 157-49, at impact parameters of 74 and 93 h {sup -1} {sub 70} kpc near its major axis and 172 h {sup -1} {sub 70} kpc along its minor axis. H I Ly{alpha} absorption is detected at the galaxy redshift in the spectra of all three QSOs, and metal lines of Si III, Si IV, and C IV are detected along the two major-axis sight lines. Photoionization models of these clouds suggest metallicities close to the galaxy metallicity, cloud sizes of {approx}1 kpc, and gas masses of {approx}10{sup 4} M {sub Sun }. Given the high covering factor of these clouds, ESO 157-49 could harbor {approx}2 Multiplication-Sign 10{sup 9} M {sub Sun} of warm CGM gas. We detect no metals in the sight line that probes the galaxy along its minor axis, but gas at the galaxy metallicity would not have detectable metal absorption with ionization conditions similar to the major-axis clouds. The kinematics of the major-axis clouds favor these being portions of a 'galactic fountain' of recycled gas, while two of the three minor-axis clouds are constrained geometrically to be outflowing gas. In addition, one of our QSO sight lines probes a second more distant spiral, ESO 157-50, along its major axis at an impact parameter of 88 h {sup -1} {sub 70} kpc. Strong H I Ly{alpha} and C IV absorption only are detected in the QSO spectrum at the redshift of ESO 157-50.

  14. A Field-Reversed Configuration Plasma Translated into a Neutral Gas Atmosphere

    Science.gov (United States)

    Sekiguchi, Jun'ichi; Asai, Tomohiko; Takahashi, Tsutomu; Ando, Hirotoshi; Arai, Mamiko; Katayama, Seri; Takahashi, Toshiki

    2014-10-01

    A field-reversed configuration (FRC) is a compact toroid dominantly with poloidal magnetic field. Because of its simply-connected configuration, an FRC can be translated axially along a gradient of guide magnetic field, and trapped in a confinement region with quasi-static external magnetic field. FRC translation experiments have been performed several facilities. Translation speed of those translated FRCs is comparable with super-Alfvenic speed of approximately 200 km/s. In this experiments, FRC translation has been performed on the FAT (FRC Amplification via Translation) facility. Achieved translation speed in the case of translation into a confinement chamber maintained as the vacuum state is in the range from 130 to 210 km/s. On the other hand, FRC translation into a statically filled deuterium gas atmosphere has also been performed. In the case of translation into filled neutral gas, FRC translation speed is approximately 80 km/s and the separatrix volume has extremely expanded compared with the case of a vacuum state. The phenomenon suggests the presence of regeneration process of translation kinetic energy back into the internal plasma energy during the translation process. This work was partially supported by ``Nihon University Symbolic Project.'' The authors gratefully acknowledge contributions from Nac Image Technology Inc. on the fast camera measurements.

  15. Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

    Science.gov (United States)

    Lebouteiller, V.; Kunth, D.; Thuan, T. X.; Désert, J. M.

    2009-02-01

    Context: Evidence has grown over the past few years that the neutral phase of blue compact dwarf (BCD) galaxies may be metal-deficient as compared to the ionized gas of their H ii regions. These results have strong implications for our understanding of the chemical evolution of galaxies, and it is essential to strengthen the method, as well as to find possible explanations. Aims: We present the analysis of the interstellar spectrum of Pox 36 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Pox 36 was selected because of the relatively low foreground gas content that makes it possible to detect absorption-lines weak enough that unseen components should not be saturated. Methods: Interstellar lines of H i, N i, O i, Si ii, P ii, Ar i, and Fe ii are detected. Column densities are derived directly from the observed line profiles except for H i, whose lines are contaminated by stellar absorption, thus needing the stellar continuum to be removed. We used the TLUSTY models to remove the stellar continuum and isolate the interstellar component. The best fit indicates that the dominant stellar population is B0. The observed far-UV flux agrees with an equivalent number of ~300 B0 stars. The fit of the interstellar H i line gives a column density of 1020.3±0.4 cm-2. Chemical abundances were then computed from the column densities using the dominant ionization stage in the neutral gas. Our abundances are compared to those measured from emission-line spectra in the optical, probing the ionized gas of the H ii regions. Results: Our results suggest that the neutral gas of Pox 36 is metal-deficient by a factor ~7 as compared to the ionized gas, and they agree with a metallicity of ≈1/35 Z_⊙. Elemental depletion is not problematic because of the low dust content along the selected lines of sight. In contrast, the ionized gas shows a clear depletion pattern, with iron being strongly depleted. Conclusions: The abundance discontinuity between the neutral and ionized phases

  16. The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift

    CERN Document Server

    Bournaud, Frederic; Renaud, Florent; Dekel, Avishai; Elmegreen, Bruce G; Elmegreen, Debra M; Teyssier, Romain; Amram, Philippe; Daddi, Emanuele; Duc, Pierre-Alain; Elbaz, David; Epinat, Benoit; Gabor, Jared M; Juneau, Stephanie; Kraljic, Katarina; Floch', Emeric Le

    2013-01-01

    Star-forming disk galaxies at high redshift are often subject to violent disk instability, characterized by giant clumps whose fate is yet to be understood. The main question is whether the clumps disrupt within their dynamical timescale (<50Myr), like molecular clouds in today's galaxies, or whether they survive stellar feedback for more than a disk orbital time (~300Myr) in which case they can migrate inward and help building the central bulge. We present 3.5-7pc resolution AMR simulations of high-redshift disks including photo-ionization, radiation pressure, and supernovae feedback (Renaud et al. 2013, and Perret et al., this astro-ph issue). Our modeling of radiation pressure determines the mass loading and initial velocity of winds from basic physical principles. We find that the giant clumps produce steady outflow rates comparable to and sometimes somewhat larger than their star formation rate, with velocities largely sufficient to escape galaxy. The clumps also lose mass, especially old stars, by ti...

  17. Sgr A* and its Environment: Low Mass Star Formation, the Origin of X-ray Gas and Collimated Outflow

    CERN Document Server

    Yusef-Zadeh, F; Schödel, R; Roberts, D A; Cotton, W; Bushouse, H; Arendt, R; Royster, M

    2016-01-01

    We present high-resolution multiwavelength radio continuum images of the region within 150$"$ of Sgr A*, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2" east-west ridge of radio emission, linking Sgr A* and a cluster of stars associated with IRS 13N and IRS 13E. The ridge suggests that an outflow of east-west blob-like structures is emerging from Sgr A*. We also find arc-like features within the ridge with morphologies suggestive of photoevaporative protoplanetary disks. We use near-IR fluxes to show that the emission has similar characteristics to those of a protoplanetary disk irradiated by the intense radiation field at the Galactic center. This suggests that star formation has taken place within the S cluster 2$"$ from Sgr A*. We suggest that the diffuse X-ray emission associated with Sgr A* is due to an expanding hot wind produced by the mass loss from B-type main sequence stars, and/or the disks of photoevaporation of low mass YSOs at a ra...

  18. The complex, dusty narrow-line region of NGC 4388: gas-jet interactions, outflows and extinction revealed by near-IR spectroscopy

    Science.gov (United States)

    Rodríguez-Ardila, A.; Mason, R. E.; Martins, L.; Ramos Almeida, C.; Riffel, R. A.; Riffel, R.; Lira, P.; González Martín, O.; Dametto, N. Z.; Flohic, H.; Ho, L. C.; Ruschel-Dutra, D.; Thanjavur, K.; Colina, L.; McDermid, R. M.; Perlman, E.; Winge, C.

    2017-02-01

    We present Gemini/GNIRS (Gemini Near-Infrared Spectrograph) spectroscopy of the Seyfert 2 galaxy NGC 4388, with simultaneous coverage from 0.85 to 2.5 μm. Several spatially extended emission lines are detected for the first time, both in the obscured and unobscured portion of the optical narrow-line region (NLR), allowing us to assess the combined effects of the central continuum source, outflowing gas and shocks generated by the radio jet on the central 280 pc gas. The H I and [Fe II] lines allow us to map the extinction affecting the NLR. We found that the nuclear region is heavily obscured, with E(B - V) ˜ 1.9 mag. To the NE of the nucleus and up to ˜150 pc, the extinction remains large, ˜1 mag or larger, consistent with the system of dust lanes seen in optical imaging. We derived position-velocity diagrams for the most prominent lines as well as for the stellar component. Only the molecular gas and the stellar component display a well-organized pattern consistent with disc rotation. Other emission lines are kinematically perturbed or show little evidence of rotation. Extended high-ionization emission of sulphur, silicon and calcium is observed to distances of at least 200 pc both NE and SW of the nucleus. We compared flux ratios between these lines with photoionization models and conclude that radiation from the central source alone cannot explain the observed high-ionization spectrum. Shocks between the radio jet and the ambient gas are very likely an additional source of excitation. We conclude that NGC 4388 is a prime laboratory to study the interplay between all these mechanisms.

  19. Disk, merger, or outflow? Molecular gas kinematics in two powerful obscured QSOs at z ≥ 3.4

    Science.gov (United States)

    Polletta, M.; Nesvadba, N. P. H.; Neri, R.; Omont, A.; Berta, S.; Bergeron, J.

    2011-09-01

    We report on the detection of bright CO(4-3) line emission in two powerful, obscured quasars discovered in the SWIRE survey, SW022513 and SW022550 at z ≥ 3.4. We analyze the line strength and profile to determine the gas mass, dynamical mass, and the gas dynamics for both galaxies. In SW022513 we may have found the first evidence for a molecular, AGN-driven wind in the early Universe. The line profile in SW022513 is broad (FWHM=1000 km s-1) and blueshifted by -200 km s-1 relative to systemic (where the systemic velocity is estimated from the narrow components of ionized gas lines, as is commonly done for AGN at low and high redshifts). SW022550 has a more regular, double-peaked profile, which is marginally spatially resolved in our data, consistent with either a merger or an extended disk. The molecular gas masses, 4 × 1010 M⊙, are large and account for powerful CO emitting galaxies at high redshift, i.e., submillimeter galaxies. Our sources exhibit relatively lower star-formation efficiencies compared to other dusty, powerful starburst galaxies at high redshift. We speculate that this could be a consequence of the AGN perturbing the molecular gas. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  20. Edge Charge Neutralization of Clay for Improved Oxygen Gas Barrier in Multilayer Nanobrick Wall Thin Films.

    Science.gov (United States)

    Song, Yixuan; Hagen, David A; Qin, Shuang; Holder, Kevin M; Falke, Kyle; Grunlan, Jaime C

    2016-12-21

    Layer-by-layer (LbL) assembled polymer-clay multilayer thin films are known to provide transparent and flexible gas barrier. In an effort to further lower the oxygen transmission rate (OTR) of these nanobrick wall thin films, sodium chloride was introduced into montmorillonite (MMT) suspension as an "indifferent electrolyte". At pH 6.5 the amphoteric edge sites of MMT have a neutral net charge, and a moderate concentration of NaCl effectively shields the charge from neighboring platelets, allowing van der Waals forces to attract the edges to one another. This edge-to-edge bonding creates a much more tortuous path for diffusing oxygen molecules. An eight-bilayer (BL) polyethylenimine (PEI)/MMT multilayer coating (∼50 nm thick), assembled with 5 mM NaCl in the aqueous clay suspension, exhibited an order of magnitude reduction in oxygen permeability (∼4 × 10(-20) cm(3)·cm/(cm(2)·Pa·s)) relative to its salt-free counterpart. This result represents the best barrier among polymer-clay bilayer systems, which is also lower than SiOx or AlxOy thin films. At higher NaCl concentration, the strong charge screening causes edge-to-face bonding among MMT nanoplatelets, which leads to misalignment in assembled films and increased OTR. This "salty-clay" strategy provides an efficient way to produce better multilayer oxygen barrier thin films by altering ionic strength of the MMT suspension. This simple modification reduces the number of layers necessary for high gas barrier, potentially making these multilayer films interesting for commercial packaging applications.

  1. Where is the Cold Neutral Gas in the Hosts of High Redshift AGN?

    CERN Document Server

    Curran, S J; Webb, J K

    2008-01-01

    Previous surveys for HI 21-cm absorption in z > 0.1 radio galaxies and quasars yield a 40% detection rate, which is attributed to unified schemes of active galactic nuclei (AGN). In this paradigm absorption is only witnessed in (close to) type-2 objects, where the central obscuration is viewed (nearly) edge-on and thus absorbs the rest frame 1420 MHz emission along our sight-line. However, we find this mix of detections and non-detections to only apply at low redshift (z 3 radio sources we find no 21-cm absorption, indicating a low abundance of cold neutral gas in (the sight-lines searched in) these objects. Analysing the spectral energy distributions of these sources, we find that our high redshift selection introduces a bias where our sample consists exclusively of quasars with ultra-violet luminosities in excess of 10e23 W/Hz. This may suggest that we have selected a class of particularly UV bright type-1 objects. Whatever the cause, it must also be invoked to explain the non-detections in an equal number...

  2. Investigating the Neutral-Gas Manometers in the Wendelstein 7-X Experimental Fusion Reactor

    Science.gov (United States)

    Maisano-Brown, Jeannette; Wenzel, Uwe; Sunn-Pederson, Thomas

    2017-01-01

    The neutral-gas manometer is a powerful diagnostic tool used in the Wendelstein 7-X stellarator, a magnetized fusion experiment located in Germany. The Wendelstein, produced at a cost of 1.2 billion euros, and 20 years in the making, had its first experimental results in Winter 2016. Initial findings exceeded expectations but further study is still necessary. The particular instrument we examined was a hot-cathode ionization gauge, critical for attaining a quality in-vessel environment and a stable plasma. However, after the winter operation of Wendelstein, we found that some of the gauges had failed the six-second (maximum) plasma runs. Wendelstein is on track for 30-minute operations within three years, so it has become of utmost importance to scrutinize gauge design claims. We therefore subjected the devices to high magnetic field, input current, and temperature, as well as to long operational periods. Our results confirmed that the manometer cannot survive a 30-minute run. Though our findings did motivate promising recommendations for design improvement and for further experimentation so that the gauge can be ready for upcoming operations in Summer 2017 and eventual installment in ITER, the International Thermonuclear Experimental Reactor, currently under construction. This research was graciously supported by the Max Planck Institute and the MIT-Germany Initiative.

  3. An absorption-selected survey of neutral gas in the Milky Way halo

    CERN Document Server

    Bekhti, N Ben; Richter, P; Kerp, J; Klein, U; Murphy, M T

    2012-01-01

    We aim at analysing systematically the distribution and physical properties of neutral and mildly ionised gas in the Milky Way halo, based on a large absorption-selected data set. Multi-wavelength studies were performed combining optical absorption line data of CaII and NaI with follow-up HI 21-cm emission line observations along 408 sight lines towards low- and high-redshift QSOs. We made use of archival optical spectra obtained with UVES/VLT. HI data were extracted from the Effelsberg-Bonn HI survey and the Galactic All-Sky survey. For selected sight lines we obtained deeper follow-up observations using the Effelsberg 100-m telescope. CaII (NaI) halo absorbers at intermediate and high radial velocities are present in 40-55% (20-35%) of the sightlines, depending on the column density threshold chosen. Many halo absorbers show multi-component absorption lines, indicating the presence of sub-structure. In 65% of the cases, absorption is associated with HI 21-cm emission. The CaII (NaI) column density distribut...

  4. The Hot and Cold Outflows of NGC 3079

    CERN Document Server

    Shafi, N; Oosterloo, T; Booth, R

    2009-01-01

    Very deep neutral hydrogen (HI) observations of the edge-on spiral galaxy NGC 3079 with the Westerbork Synthesis Radio Telescope (WSRT) are presented. The galaxy has been studied extensively in different wavelengths and known for its several unique and complex features. However, the new data still revealed several new features and show that the galaxy is even more complicated and interesting than previously thought. In the new data a large stream of gas, encircling the entire galaxy, was discovered, while the data also show, for the first time, that not only hot gas is blown into space by the starburst/AGN, but also large amounts of cold gas, despite the high energies involved in the outflow.

  5. Collision Experiment of an Arched Plasma-Filled Flux Rope and a Target Cloud of Initially Neutral Gas

    Science.gov (United States)

    Wongwaitayakornkul, Pakorn; Bellan, Paul; Li, Hui; Li, Shengtai

    2016-10-01

    Shocks occur in the co-rotating interaction regions just beyond the solar corona, in the corona during CME events, and when the solar wind impacts Earth's magnetosphere. The Caltech solar loop experiment investigates shock physics by creating an arched plasma-filled flux rope that expands to collide with a pre-injected, initially-neutral gas. We focus the investigation on the situation of a heavy-gas plasma (Argon) impacting a much lighter neutral gas cloud (Hydrogen). The neutral gas target cloud ionizes immediately upon being impacted and plasma-induced shock waves propagate in the target cloud away from the impact region. Analysis of data from magnetic probes, Langmuir probes, a fast camera, and spectroscopic measurements will be presented. The measurements suggest that a thin, compressed, ionized layer of hydrogen is formed just downstream of the Argon plasma loop and that thin, supersonic shocks form further downstream and propagate obliquely away from the plasma loop. Numerical simulation of an ideal MHD plasma is underway to enable comparison of the measurements with the predictions of MHD theory.

  6. Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust.

    Science.gov (United States)

    Dunk, Paul W; Adjizian, Jean-Joseph; Kaiser, Nathan K; Quinn, John P; Blakney, Gregory T; Ewels, Christopher P; Marshall, Alan G; Kroto, Harold W

    2013-11-01

    Carbonaceous presolar grains of supernovae origin have long been isolated and are determined to be the carrier of anomalous (22)Ne in ancient meteorites. That exotic (22)Ne is, in fact, the decay isotope of relatively short-lived (22)Na formed by explosive nucleosynthesis, and therefore, a selective and rapid Na physical trapping mechanism must take place during carbon condensation in supernova ejecta. Elucidation of the processes that trap Na and produce large carbon molecules should yield insight into carbon stardust enrichment and formation. Herein, we demonstrate that Na effectively nucleates formation of Na@C60 and other metallofullerenes during carbon condensation under highly energetic conditions in oxygen- and hydrogen-rich environments. Thus, fundamental carbon chemistry that leads to trapping of Na is revealed, and should be directly applicable to gas-phase chemistry involving stellar environments, such as supernova ejecta. The results indicate that, in addition to empty fullerenes, metallofullerenes should be constituents of stellar/circumstellar and interstellar space. In addition, gas-phase reactions of fullerenes with polycyclic aromatic hydrocarbons are investigated to probe "build-up" and formation of carbon stardust, and provide insight into fullerene astrochemistry.

  7. Quantifying Supernovae-driven Multiphase Galactic Outflows

    Science.gov (United States)

    Li, Miao; Bryan, Greg L.; Ostriker, Jeremiah P.

    2017-06-01

    Galactic outflows are observed everywhere in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass, and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming the SN rate scales with gas surface density Σgas as in the Kennicutt-Schmidt relation, we find that the mass loading factor, η m, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing Σgas as {η }{{m}}\\propto {{{Σ }}}{gas}-0.61. Approximately Σgas ≲ 50 M ⊙ pc-2 marks when η m ≳ 1. About 10%-50% of the energy and 40%-80% of the metals produced by SNe end up in the outflows. The tenuous hot phase (T > 3 × 105 K), which fills 60%-80% of the volume at the midplane, carries the majority of the energy and metals in the outflows. We discuss how various physical processes, including the vertical distribution of SNe, photoelectric heating, external gravitational field, and SN rate, affect the loading efficiencies. The relative scale height of gas and SNe is a very important factor in determining the loading efficiencies.

  8. Emergence of a Quasar Outflow

    CERN Document Server

    Hamann, F; Hidalgo, P Rodriguez; Prochaska, J X; Herbert-Fort, S

    2008-01-01

    We report the first discovery of the emergence of a high-velocity broad-line outflow in a luminous quasar, J105400.40+034801.2 at redshift z ~ 2.1. The outflow is evident in ultraviolet CIV and SiIV absorption lines with velocity shifts v ~ 26,300 km/s and deblended widths FWHM ~ 4000 km/s. These features are marginally strong and broad enough to be considered broad absorption lines (BALs), but their large velocities exclude them from the standard BAL definition. The outflow lines appeared between two observations in the years 2002.18 and 2006.96. A third observation in 2008.48 showed the lines becoming ~40% weaker and 10% to 15% narrower. There is no evidence for acceleration or for any outflow gas at velocities 21.2 and average space density n_H > 2 x 10^5 cm^-3. We attribute the emergence of the outflow lines to a substantial flow structure moving across our line of sight, possibly near the ragged edge of the main BAL flow or possibly related to the onset of a BAL evolutionary phase.

  9. The complexity of the coronal line region in AGNs: Gas-jet interactions and outflows revealed by NIR spectroscopy

    Science.gov (United States)

    Rodríguez-Ardila, Alberto; Prieto, Almudena; Mazzalay, Ximena

    2016-08-01

    Apart from the classical broad line region (BLR) at small core distances, and the extended classical narrow-line region (NLR), a subset of active galactic nuclei (AGN) show, in their spectra, lines from very highly ionised atoms, known as Coronal lines (CLs). The precise nature and origin of these CLs remain uncertain. Advances on this matter include the determination of the size and morphology of the CLR by means of optical HST and ground-based AO imaging/spectroscopy in a few AGNs. The results indicate CLRs with sizes varying from compact (~30 pc) to extended (~200 pc) emission and aligned preferentially with the direction of the lower ionisation cones seen in these sources. In this talk, we present results of a pioneering work aimed at studying the CLR in the near-infrared region on a selected sample of nearby AGNs. The excellent angular resolution of the data allowed us to resolve and map the extension of the coronal line gas and compare it to that emitting low- and mid-ionization lines. In most cases, the very good match between the radio emission and the CLR suggest that at least part of the high-ionization gas is jet-driven. Results from photoionization models where the central engine is the only source of energy input strongly fail at reproducing the observed line ratios, mainly at distances larger than 60 pc from the centre. We discuss here other processes that should be at work to enhance this energetic emission and suggest that the presence of coronal lines in AGNs is an unambiguous signature of feedback processes in these sources.

  10. Outflow - Core Interaction in Barnard 1

    CERN Document Server

    Hiramatsu, Masaaki; Takakuwa, Shigehisa

    2010-01-01

    In order to study how outflows from protostars influence the physical and chemical conditions of the parent molecular cloud, we have observed Barnard 1 (B1) main core, which harbors four Class 0 and three Class I sources, in the CO (J=1-0), CH3OH (J_K=2_K-1_K), and the SiO (J=1-0) lines using the NRO 45 m telescope. We have identified three CO outflows in this region; one is an elongated (~ 0.3 pc) bipolar outflow from a Class 0 protostar B1-c in the submillimeter clump SMM 2, another is a rather compact (~ 0.1 pc) outflow from a Class I protostar B1 IRS in the clump SMM 6, and the other is extended outflow from a Class I protostar in SMM 11. In the western lobe of the SMM 2 outflow, both the SiO and CH3OH lines show broad redshifted wings with the terminal velocities of 25 km/s and 13 km/s, respectively. It is likely that the shocks caused by the interaction between the outflow and ambient gas enhance the abundance of SiO and CH3OH in the gas phase. The total energy input rate by the outflows (1.1x10^{-3} Ls...

  11. Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

    Science.gov (United States)

    Schowalter, Steven J.; Dunning, Alexander J.; Chen, Kuang; Puri, Prateek; Schneider, Christian; Hudson, Eric R.

    2016-08-01

    Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to 10 barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behaviour as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behaviour leads to the limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying non-equilibrium thermodynamics at the atomic level.

  12. Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

    CERN Document Server

    Schowalter, Steven J; Chen, Kuang; Puri, Prateek; Schneider, Christian; Hudson, Eric R

    2016-01-01

    Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to ten barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behavior as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behavior leads to limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying nonequilibrium thermodynamics.

  13. Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

    Science.gov (United States)

    Schowalter, Steven J.; Dunning, Alexander J.; Chen, Kuang; Puri, Prateek; Schneider, Christian; Hudson, Eric R.

    2016-01-01

    Sympathetic cooling of trapped ions through collisions with neutral buffer gases is critical to a variety of modern scientific fields, including fundamental chemistry, mass spectrometry, nuclear and particle physics, and atomic and molecular physics. Despite its widespread use over four decades, there remain open questions regarding its fundamental limitations. To probe these limits, here we examine the steady-state evolution of up to 10 barium ions immersed in a gas of three-million laser-cooled calcium atoms. We observe and explain the emergence of nonequilibrium behaviour as evidenced by bifurcations in the ion steady-state temperature, parameterized by ion number. We show that this behaviour leads to the limitations in creating and maintaining translationally cold samples of trapped ions using neutral-gas sympathetic cooling. These results may provide a route to studying non-equilibrium thermodynamics at the atomic level. PMID:27511602

  14. Measurements of the ion velocity distribution in an ultracold neutral plasma derived from a cold, dense Rydberg gas

    OpenAIRE

    S. D. Bergeson; Lyon, M

    2016-01-01

    We report measurements of the ion velocity distribution in an ultracold neutral plasma derived from a dense, cold Rydberg gas in a MOT. The Rydberg atoms are excited using a resonant two-step excitation pathway with lasers of 4 ns duration. The plasma forms spontaneously and rapidly. The rms width of the ion velocity distribution is determined by measuring laser-induced fluorescence (LIF) of the ions. The measured excitation efficiency is compared with a Monte-Carlo wavefunction calculation, ...

  15. Gas-phase energies of actinide oxides -- an assessment of neutral and cationic monoxides and dioxides from thorium to curium

    Energy Technology Data Exchange (ETDEWEB)

    Marcalo, Joaquim; Gibson, John K.

    2009-08-10

    An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and with condensed-phase thermochemistry.

  16. Double ionization effect in electron accelerations by high-intensity laser pulse interaction with a neutral gas

    Science.gov (United States)

    Nandan Gupta, Devki

    2013-11-01

    We study the effect of laser-induced double-ionization of a helium gas (with inhomogeneous density profile) on vacuum electron acceleration. For enough laser intensity, helium gas can be found doubly ionized and it strengthens the divergence of the pulse. The double ionization of helium gas can defocus the laser pulse significantly, and electrons are accelerated by the front of the laser pulse in vacuum and then decelerated by the defocused trail part of the laser pulse. It is observed that the electrons experience a very low laser-intensity at the trailing part of the laser pulse. Hence, there is not much electron deceleration at the trailing part of the pulse. We found that the inhomogeneity of the neutral gas reduced the rate of tunnel ionization causing less defocusing of the laser pulse and thus the electron energy gain is reduced.

  17. Double ionization effect in electron accelerations by high-intensity laser pulse interaction with a neutral gas

    Directory of Open Access Journals (Sweden)

    Gupta Devki Nandan

    2013-11-01

    Full Text Available We study the effect of laser-induced double-ionization of a helium gas (with inhomogeneous density profile on vacuum electron acceleration. For enough laser intensity, helium gas can be found doubly ionized and it strengthens the divergence of the pulse. The double ionization of helium gas can defocus the laser pulse significantly, and electrons are accelerated by the front of the laser pulse in vacuum and then decelerated by the defocused trail part of the laser pulse. It is observed that the electrons experience a very low laser-intensity at the trailing part of the laser pulse. Hence, there is not much electron deceleration at the trailing part of the pulse. We found that the inhomogeneity of the neutral gas reduced the rate of tunnel ionization causing less defocusing of the laser pulse and thus the electron energy gain is reduced.

  18. DIAGNOSTICS OF AGN-DRIVEN MOLECULAR OUTFLOWS IN ULIRGs FROM HERSCHEL-PACS OBSERVATIONS OF OH AT 119 μm

    Energy Technology Data Exchange (ETDEWEB)

    Spoon, H. W. W.; Lebouteiller, V. [Cornell University, CRSR, Space Sciences Building, Ithaca, NY 14853 (United States); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); González-Alfonso, E. [Departamento de Física y Matemáticas, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Bernard-Salas, J. [Department of Physical Sciences, Milton Keynes MK7 6AA (United Kingdom); Urrutia, T. [Leibniz Institut für Astrophysik, Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Rigopoulou, D.; Verma, A. [Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Westmoquette, M. S. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Smith, H. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Afonso, J. [Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal); Pearson, C. [RAL Space, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX (United Kingdom); Cormier, D. [Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany); Efstathiou, A. [School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia (Cyprus); Borys, C. [Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States); Etxaluze, M. [Departamento de Astrofísica. Centro de Astrobiología. CSIC-INTA. Torrejón de Ardoz, E-28850 Madrid (Spain); Clements, D. L., E-mail: spoon@isc.astro.cornell.edu [Physics Department, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2013-10-01

    We report on our observations of the 79 and 119 μm doublet transitions of OH for 24 local (z < 0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH 119 μm profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, while other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This result locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to ∼2000 km s{sup –1}, with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km s{sup –1} (1000 km s{sup –1}). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km s{sup –1} are thought to require an active galactic nucleus (AGN) to drive them, about two-thirds of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity. No such correlation is found with the IR-derived star formation rate. The highest outflow velocities are found among sources that are still deeply embedded. We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less-obscured AGNs. Four of our sources show high-velocity wings in their [C II] fine-structure line profiles, implying neutral gas outflow masses of at least (2-4.5) × 10{sup 8} M{sub ☉}.

  19. Quantifying Supernovae-Driven Multiphase Galactic Outflows

    CERN Document Server

    Li, Miao; Ostriker, Jeremiah P

    2016-01-01

    Galactic outflows are ubiquitously observed in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming SN rate scales with gas surface density $\\Sigma_{\\rm{gas}}$ as in the Kennicutt-Schmidt (KS) relation, we find the mass loading factor, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing $\\Sigma_{\\rm{gas}}$ as $\\propto \\Sigma^{-0.61}_{\\rm{gas}}$. Approximately $\\Sigma_{\\rm{gas}} \\lesssim$ 50 $M_\\odot/pc^2$ marks when the mass loading factor $\\gtrsim$1. About 10-50\\% of the energy and 40-80\\% of the metals produced by SNe end up in the outflows. The tenuous hot phase ($T>3\\times 10^5$ K) carries the majority of the energy and metals in outflows. We discuss how various physical...

  20. Can galactic outflows explain the properties of Ly-alpha emitters?

    CERN Document Server

    Orsi, Alvaro; Baugh, Carlton M

    2011-01-01

    We study the properties of Ly-alpha emitters in a cosmological framework by computing the escape of Ly-alpha photons through galactic outflows. We combine the GALFORM semi-analytical model of galaxy formation with a Monte Carlo Ly-alpha radiative transfer code. The properties of Ly-alpha emitters at 0outflow geometries: a Shell of neutral gas and a Wind ejecting material, both expanding at constant velocity. We characterise the differences in the Ly-alpha line profiles predicted by the two outflow geometries in terms of their width, asymmetry and shift from the line centre for a set of outflows with different hydrogen column densities, expansion velocities and metallicities. In general, the Ly-alpha line profile of the Shell geometry is broader and more asymmetric, and the Ly-alpha escape fraction is lower than with the Wind geometry for the same set of parameters. In order to implement the outflow geometries in the semi-analytical model GALFORM, a number of free parameters ...

  1. Capillary gas chromatographic analysis of alditol acetates of neutral and amino sugars in bacterial cell walls.

    Science.gov (United States)

    Fox, A; Morgan, S L; Hudson, J R; Zhu, Z T; Lau, P Y

    1983-02-18

    Several improvements in the preparation of alditol acetates of neutral and amino sugars and in the preparation of glass capillary columns for their separation are described. Modifications in sample preparation permitted the simultaneous processing of multiple samples and eliminated extraneous background peaks. Efficient and inert columns were tailor-made for the separation of alditol acetates of neutral and amino sugars by leaching glass capillaries with aqueous hydrochloric acid and dynamically coating with SP-2330.

  2. Bursty star formation feedback and cooling outflows

    Science.gov (United States)

    Suarez, Teresita; Pontzen, Andrew; Peiris, Hiranya V.; Slyz, Adrianne; Devriendt, Julien

    2016-10-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circum-galactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disc can be modelled as a rapidly moving bubble of hot gas at ˜1 kpc above disc, then ask what happens as it moves out further into the halo around the galaxy on ˜100 kpc scales. To do this, we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the `burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in the CGM may therefore change in response to the detailed historical pattern of star formation. For instance, outflows generated by star formation with short, intense bursts contain up to 60 per cent of their gas mass at temperatures <5 × 104 K; for near-continuous star formation, the figure is ≲5 per cent. Further study of cosmological simulations, and of idealized simulations with e.g. metal-cooling, magnetic fields and/or thermal conduction, will help to understand the precise signature of bursty outflows on observed ion abundances.

  3. Another piece of the puzzle: The fast H I outflow in Mrk 231

    Science.gov (United States)

    Morganti, Raffaella; Veilleux, Sylvain; Oosterloo, Tom; Teng, Stacy H.; Rupke, David

    2016-09-01

    We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast H I 21 cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow H I absorption blueshifted ~1300 km s-1 with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15 × 1018Tspin cm-2. We derive the Tspin to lie in the range 400-2000 K and the corresponding H I densities are nHI ~ 10-100 cm-3. Our results complement previous findings and confirm the multiphase nature of the outflow in Mrk 231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the H I outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by Na I and molecular gas in this source. Our results suggest that an H I component is present in fast outflows regardless of the acceleration mechanism (wind vs. jet driven) and that it must be connected with common properties of the pre-interaction gas involved. Considering the observed similarity of their column densities, the H I outflow likely represents the inner part of the broad wind identified on larger scales in atomic Na I. The mass outflow rate of the H I outflow (between 8 and 18 M⊙ yr-1) does not appear to be as large as that observed in molecular gas, partly owing to the smaller sizes of the outflowing region sampled by the H I absorption. These characteristics are commonly seen in other cases of outflows driven by the active galactic nucleus (AGN) suggesting that the H I may represent a short intermediate phase in the rapid cooling of the gas. The results further confirm H I as a good tracer for AGN-driven outflows not only in powerful radio sources. We also obtained deeper continuum

  4. Bursty star formation feedback and cooling outflows

    CERN Document Server

    Suarez, Teresita; Peiris, Hiranya V; Slyz, Adrianne; Devriendt, Julien

    2016-01-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circumgalactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disk can be modelled as a rapidly moving bubble of hot gas at $\\mathrm{\\sim1\\;kpc}$ above disk, then ask what happens as it moves out further into the halo around the galaxy on $\\mathrm{\\sim 100\\;kpc}$ scales. To do this we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the 'burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in th...

  5. Bending and turbulent enhancement phenomena of neutral gas flow containing an atmospheric pressure plasma by applying external electric fields measured by schlieren optical method

    Science.gov (United States)

    Yamada, Hiromasa; Yamagishi, Yusuke; Sakakita, Hajime; Tsunoda, Syuichiro; Kasahara, Jiro; Fujiwara, Masanori; Kato, Susumu; Itagaki, Hirotomo; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Yutaka; Ikehara, Yuzuru; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki

    2016-01-01

    To understand the mechanism of turbulent enhancement phenomena of a neutral gas flow containing plasma ejected from the nozzle of plasma equipment, the schlieren optical method was performed to visualize the neutral gas behavior. It was confirmed that the turbulent starting point became closer to the nozzle exit, as the amplitude of discharge voltage (electric field) increased. To study the effect of electric field on turbulent enhancement, two sets of external electrodes were arranged in parallel, and the gas from the nozzle was allowed to flow between the upper and lower electrodes. It was found that the neutral gas flow was bent, and the bending angle increased as the amplitude of the external electric field increased. The results obtained using a simple model analysis roughly coincide with experimental data. These results indicate that momentum transport from drifted ions induced by the electric field to neutral particles is an important factor that enhances turbulence.

  6. Hot Outflows in Galaxy Clusters

    CERN Document Server

    Kirkpatrick, C C

    2015-01-01

    The gas-phase metallicity distribution has been analyzed for the hot atmospheres of 29 galaxy clusters using {\\it Chandra X-ray Observatory} observations. All host brightest cluster galaxies (BCGs) with X-ray cavity systems produced by radio AGN. We find high elemental abundances projected preferentially along the cavities of 16 clusters. The metal-rich plasma was apparently lifted out of the BCGs with the rising X-ray cavities (bubbles) to altitudes between twenty and several hundred kiloparsecs. A relationship between the maximum projected altitude of the uplifted gas (the "iron radius") and jet power is found with the form $R_{\\rm Fe} \\propto P_{\\rm jet}^{0.45}$. The estimated outflow rates are typically tens of solar masses per year but exceed $100 ~\\rm M_\\odot ~yr^{-1}$ in the most powerful AGN. The outflow rates are 10% to 20% of the cooling rates, and thus alone are unable to offset a cooling inflow. Nevertheless, hot outflows effectively redistribute the cooling gas and may play a significant role at ...

  7. Coupled two-dimensional edge plasma and neutral gas modeling of tokamak scrape-off-layers

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, R. [North Carolina State Univ., Raleigh, NC (United States)

    1992-08-01

    The objective of this study is to devise a detailed description of the tokamak scrape-off-layer (SOL), which includes the best available models of both the plasma and neutral species and the strong coupling between the two in many SOL regimes. A good estimate of both particle flux and heat flux profiles at the limiter/divertor target plates is desired. Peak heat flux is one of the limiting factors in determining the survival probability of plasma-facing-components at high power levels. Plate particle flux affects the neutral flux to the pump, which determines the particle exhaust rate. A technique which couples a two-dimensional (2-D) plasma and a 2-D neutral transport code has been developed (coupled code technique), but this procedure requires large amounts of computer time. Relevant physics has been added to an existing two-neutral-species model which takes the SOL plasma/neutral coupling into account in a simple manner (molecular physics model), and this model is compared with the coupled code technique mentioned above. The molecular physics model is benchmarked against experimental data from a divertor tokamak (DIII-D), and a similar model (single-species model) is benchmarked against data from a pump-limiter tokamak (Tore Supra). The models are then used to examine two key issues: free-streaming-limits (ion energy conduction and momentum flux) and the effects of the non-orthogonal geometry of magnetic flux surfaces and target plates on edge plasma parameter profiles.

  8. Interstellar neutral flow characteristics, composition, and interaction with the heliosphere - neutral gas and pickup ion analysis from ongoing observations and perspectives for IMAP

    Science.gov (United States)

    Moebius, E.; Bzowski, M.; Drews, C.; Frisch, P. C.; Fuselier, S. A.; Galli, A.; Gloeckler, G.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Park, J.; Schwadron, N.; Swaczyna, P.; Sokol, J. M.; Wood, B. E.; Wurz, P.

    2015-12-01

    The Sun's motion relative to the surrounding interstellar medium leads to an interstellar neutral (ISN) wind through the heliosphere that is moderately depleted by ionization. This situation allows remote sensing of the ISN through resonant scattering of solar UV and in-situ sampling, first via pickup ions (PUI) and most recently with direct neutral atom imaging. PUI observations have revealed the gravitational focusing cone of interstellar He and Ne as well as the composition of high ionization potential elements. After the first direct ISN He observations with Ulysses GAS, the Interstellar Boundary Explorer (IBEX) observes with high collecting power the ISN flow trajectories very close to their perihelion in Earth's orbit for H, He, O, and Ne from December through March. Meanwhile, IBEX has recorded seven years of ISN observations, with changing solar activity and varying viewing strategies. These recurring and remarkably repeatable observations allow us to consolidate the derived physical parameters and some key compositional aspects of the interstellar medium. IBEX observations provide a very precise relation between ISN flow longitude and speed via the hyperbolic trajectory equation, but with larger uncertainties separately for longitude and speed. Recent concerted studies have led to a velocity vector that is consistent between IBEX and Ulysses, with a substantially higher temperature than found previously. The fact that the IBEX He and O ISN observations contain a substantial secondary neutral contribution adds complexity to the quantitative analysis of the physical interstellar medium parameters. However, their discovery also provides invaluable insight into the interstellar plasma interaction in the outer heliosheath, which is shaped strongly by the interstellar magnetic field. The longitude range of the IBEX observations limits the precision of the ISN velocity vector. The IBEX collection power and its sensitivity to the Earth's magnetosphere limit

  9. Neutral hydrogen gas, past and future star formation in galaxies in and around the `Sausage' merging galaxy cluster

    Science.gov (United States)

    Stroe, Andra; Oosterloo, Tom; Röttgering, Huub J. A.; Sobral, David; van Weeren, Reinout; Dawson, William

    2015-09-01

    CIZA J2242.8+5301 (z = 0.188, nicknamed `Sausage') is an extremely massive (M200 ˜ 2.0 × 1015 M⊙), merging cluster with shock waves towards its outskirts, which was found to host numerous emission line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope H I observations of the `Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission line galaxies in the `Sausage' cluster have, on average, as much H I gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large H I reservoirs are expected to be consumed within ˜0.75-1.0 Gyr by the vigorous SF and active galactic nuclei activity and/or driven out by the outflows we observe. We find that the star formation rate (SFR) in a large fraction of H α emission line cluster galaxies correlates well with the radio broad-band emission, tracing supernova remnant emission. This suggests that the cluster galaxies, all located in post-shock regions, may have been undergoing sustained SFR for at least 100 Myr. This fully supports the interpretation proposed by Stroe et al. and Sobral et al. that gas-rich cluster galaxies have been triggered to form stars by the passage of the shock.

  10. Natural gas and renewable methane for powertrains future strategies for a climate-neutral mobility

    CERN Document Server

    2016-01-01

    This book focuses on natural gas and synthetic methane as contemporary and future energy sources. Following a historical overview, physical and chemical properties, occurrence, extraction, transportation and storage of natural gas are discussed. Sustainable production of natural gas and methane as well as production and storage of synthetic methane are scrutinized next. A substantial part of the book addresses construction of vehicles for natural and synthetic methane as well as large engines for industrial and maritime use. The last chapters present some perspectives on further uses of renewable liquid fuels as well as natural gas for industrial engines and gas power plants.

  11. Detection of CO Outflow in Rotating Cores

    Institute of Scientific and Technical Information of China (English)

    Xin Guan; Yue-Fang Wu

    2008-01-01

    We investigate the effect of bulk motion on the detection of molecular outflows in the sources S 146, GGD27, and IRAS 22566+5830. The traditional techniques do allow for bulk motions or systematic VLSR shifts of the core emissions, which may cause contamination of the high velocity gas emissions, and outflows may either fail to be detected or have their properties miscalculated. We used a program to follow the systematic shift of VLSR and better results have been obtained.

  12. The ESO UVES Advanced Data Products Quasar Sample - II. Cosmological Evolution of the Neutral Gas Mass Density

    CERN Document Server

    Zafar, Tayyaba; Popping, Attila; Milliard, Bruno; Deharveng, Jean-Michel; Frank, Stephan

    2013-01-01

    Quasar foreground damped absorbers, associated with HI-rich galaxies allow to estimate the neutral gas mass over cosmic time, which is a possible indicator of gas consumption as star formation proceeds. The DLAs and sub-DLAs are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we present the results of a search for DLAs and sub-DLAs in the ESO-UVES Advanced Data Products dataset of 250 quasars. Here we use an unbiased sub-sample of sub-DLAs from this dataset. We build a subset of 122 quasars ranging from 1.5

  13. Metal enrichment of the neutral gas of blue compact dwarf galaxies: the compelling case of Pox 36

    CERN Document Server

    Lebouteiller, V; Thuan, T X; Désert, J M

    2008-01-01

    We present the analysis of the interstellar spectrum of Pox 36 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Pox 36 was selected because of the relatively low foreground gas content that makes it possible to detect absorption-lines weak enough that unseen components should not be saturated. Interstellar lines of HI, NI, OI, SiII, PII, ArI, and FeII are detected. Column densities are derived directly from the observed line profiles except for HI, whose lines are contaminated by stellar absorption. We used the TLUSTY models to remove the stellar continuum and isolate the interstellar component. The best fit indicates that the dominant stellar population is B0. The fit of the interstellar HI line gives a column density of 10^{20.3\\pm0.4} cm-2. Chemical abundances were then computed from the column densities using the dominant ionization stage in the neutral gas. Our abundances are compared to those measured from emission-line spectra in the optical. Our results suggest that the neutral gas of Pox 36 is...

  14. Shining A Light On Galactic Outflows: Photo-Ionized Outflows

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei; Wofford, Aida

    2016-01-01

    We study the ionization structure of galactic outflows in 37 nearby, star forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to characterize the different ionization states of outflowing gas. We measure the equivalent widths, line widths, and outflow velocities of the four transitions, and find shallow scaling relations between them and galactic stellar mass and star formation rate. Regardless of the ionization potential, lines of similar strength have similar velocities and line widths, indicating that the four transitions can be modeled as a co-moving phase. The Si equivalent width ratios (e.g. Si IV/Si II) have low dispersion, and little variation with stellar mass; while ratios with O I and Si vary by a factor of 2 for a given stellar mass. Photo-ionization models reproduce these equivalent width ratios, while shock models under predict the relative amount of high ionization gas. The photo-ionization mo...

  15. Far-IR spectroscopy of the galactic center: Neutral and ionized gas in the central 10 pc of the galaxy

    Science.gov (United States)

    Hollenbach, D. J.; Watson, D. M.; Townes, C. H.; Dinerstein, H. L.; Hollenbach, D.; Lester, D. F.; Werner, M.; Storey, J. W. V.

    1983-01-01

    The 3P1 - 3P2 fine structure line emission from neutral atomic oxygen at 63 microns in the vicinity of the galactic center was mapped. The emission is extended over more than 4' (12 pc) along the galactic plane, centered on the position of Sgr A West. The line center velocities show that the O I gas is rotating around the galactic center with an axis close to that of the general galactic rotation, but there appear also to be noncircular motions. The rotational velocity at R is approximately 1 pc corresponds to a mass within the central pc of about 3 x 10(6) solar mass. Between 1 and 6 pc from the center the mass is approximately proportional to radius. The (O I) line probability arises in a predominantly neutral, atomic region immediately outside of the ionized central parsec of out galaxy. Hydrogen densities in the (O I) emitting region are 10(3) to 10(6) cm(-3) and gas temperatures are or = 100 K. The total integrated luminosity radiated in the line is about 10(5) solar luminosity, and is a substantial contribution to the cooling of the gas. Photoelectric heating or heating by ultraviolet excitation of H2 at high densities (10(5) cm(-3)) are promising mechanisms for heating of the gas, but heating due to dissipation of noncircular motions of the gas may be an alternative possibility. The 3P1 - 3P0 fine structure line of (O III) at 88 microns toward Sgr A West was also detected. The (O III) emission comes from high density ionized gas (n 10(4) cm(-3)), and there is no evidence for a medium density region (n 10(3) cm(-3)), such as the ionized halo in Sgr A West deduced from radio observations. This radio halo may be nonthermal, or may consist of many compact, dense clumps of filaments on the inner edges of neutral condensations at R or = 2 pc.

  16. Analysis of fecal bile acids and neutral steroids using gas-liquid chromatography

    NARCIS (Netherlands)

    Srikumar, T.S.; Wezendonk, B.; Dokkum, W. van

    1998-01-01

    In the present pilot study, for investigating the physiological effects of different types of nondigestible oligosaccharides, we have validated the application of methodologies for the analysis of bile acids and neutral steroids in feces of human subjects. The accuracy of the extraction and chromato

  17. Modeling the Neutral Gas and Plasma Environment of Jupiter's Moon Europa

    Science.gov (United States)

    Rubin, Martin; Tenishev, Valeriy; Hansen, Kenneth; Jia, Xianzhe; Combi, Michael; Gombosi, Tamas

    Jupiter's moon Europa has a thin gravitationally bound neutral atmosphere, which is mostly created through sputtering of high-energy ions impacting on its icy surface. The interaction of Europa with the Jovian magnetosphere is simulated using the magnetohydrodynamics (MHD) model BATSRUS. We start from the model by Kabin et al. [JGR, Vol. 104, No. A9, (1999)], which accounts for the exospheric mass loading, ion-neutral charge exchange, and ion-electron recombination. The derived magnetic field topology and plasma speeds are used to calculate the Lorentz force for our test particle Monte Carlo model. We use this model to simulate Europa's plasma and neutral environment by tracking particles created on the moon's surface by sputtering or sublimation, through dissociation and/or ionization in the atmosphere, or entering the system from Jupiter's magnetosphere as high energy ions. Neutral particle trajectories are followed by solving the equation of motion in Europa's gravity field whereas the ion population is additionally subject to the Lorentz force. We will show preliminary results of this work with application to the missions to the Jupiter system currently under consideration by NASA (JEO) and ESA (JGO).

  18. The Vertical Structure, Ionization, and Kinematic Structure of Spiral Arm Outflows Inside and Outside the Solar Circle

    Science.gov (United States)

    Gostisha, Martin; Benjamin, R. A.; Haffner, L. M.; Hill, A. S.; Barger, K. A.

    2013-06-01

    Velocity-resolved surveys of the Galactic plane with the Wisconsin H-alpha Mapper indicate a thick distribution of ~1 kpc for the ionized gas layer of the Galaxy, but also show that the emission is enhanced in the vicinity of spiral arms. We characterize the vertical scale-heights of the Perseus Arm and Scutum-Centaurus Arm as a function of azimuth and compare the structure of these arms in ionized gas (from WHAM) and neutral gas (from the Leiden-Argentina-Bonn survey). We then explore the hypothesis that these arms are the sources of correlated outflow from the Galactic disk and compare the observed velocity structure of the arms with different predictions for outflow kinematics.

  19. Periodic modulation of gas giant magnetospheres by the neutral upper atmosphere

    Directory of Open Access Journals (Sweden)

    C. G. A. Smith

    2006-10-01

    Full Text Available Periodic signatures present in the magnetospheres of both Jupiter and Saturn have yet to be fully explained. At Jupiter the unexplained signatures are related to emissions from the Io torus ("System IV"; at Saturn they are observed in emissions of kilometric radiation (SKR and in magnetometer data. These signatures are often interpreted in terms of magnetic field anomalies. This paper describes an alternative mechanism by which the neutral atmosphere may impose such periodic signatures on the magnetosphere. The mechanism invokes a persistent zonal asymmetry in the neutral wind field that rotates with the planet. This asymmetry must be coupled to substantial ionospheric conductivity. It is then able to drive divergent currents in the upper atmosphere that close in and perturb the magnetosphere. We estimate the conductivities and wind speeds required for these perturbations to be significant, and argue that they are most likely to be important at auroral latitudes where the conductivity may be enhanced by particle precipitation.

  20. Upper-Thermospheric Observations and Neutral-Gas Dynamics at High Latitudes During Solar Maximum.

    Science.gov (United States)

    1987-01-01

    aeasFPIgure 6.5, ecep orB> oniios -40 TO~ -- 12 p . p’ T5 .ww i - IO RFS 5 183 maximum antisunward neutral winds located in the center of the polar cap. The...Solar flux variability in the *- Schumann-Runge continuum as a function of solar cycle 21. J. Geophys. Res., 85, 6063 - 6068, 1980c. Torr, M. R., P. G

  1. Kinetic Modeling of the Neutral Gas, Ions, and Charged Dust in Europa's Exosphere

    Science.gov (United States)

    Tenishev, V.; Borovikov, D.; Rubin, M.; Jia, X.; Combi, M. R.

    2015-12-01

    The interaction of the Jovian magnetosphere with Europa has been a subject of active research during the last few decades both through in-situ and remote sensing observations as well as theoretical considerations. Linking the magnetosphere and the moon's surface and interior, Europa's exosphere has become one of the primary objects of study in the field. Understanding the physical processes occurring in the exosphere and its chemical composition is required for the understanding of the interaction between Europa and Jupiter. Europa's surface-bound exosphere originates mostly from ion sputtering of the water ice surface. Minor neutral species and ions of exospheric origin are produced via photolytic and electron impact reactions. The interaction of the Jovian magnetosphere and Europa affects the exospheric population of both neutrals and ions via source and loss processes. Moreover, the Lorentz force causes the newly created exospheric ions to move preferably aligned with the magnetic field lines. Contrary to the ions, heavier and slow-moving charged dust grains are mostly affected by gravity and the electric field component of the Lorentz force. As a result, escaping dust forms a narrow tail aligned in the direction of the convection electric field. Here we present results of a kinetic model of the neutral species (H2O, OH, O2, O, and H), ions (O+, O2+, H+, H2+, H2O+, and OH+), and neutral and charged dust in Europa's exosphere. In our model H2O and O2 are produced via sputtering and other exospheric neutral and ions species are produced via photolytic and electron impact reactions. For the charged dust we compute the equilibrium grain charge by balancing the electron and ion collecting currents according to the local plasma flow conditions at the grain's location. For the tracking of the ions, charged dust, and the calculation of the grains' charge we use plasma density and velocity, and the magnetic field derived from our multi-fluid MHD model of Europa

  2. Measurement of neutral gas pressure in the D-module of GAMMA 10/PDX by using ASDEX type fast ionization gauge

    Science.gov (United States)

    Ichimura, K.; Fukumoto, M.; Islam, M. M.; Islam, M. S.; Shimizu, K.; Fukui, K.; Ohuchi, M.; Nojiri, K.; Terakado, A.; Yoshikawa, M.; Ezumi, N.; Sakamoto, M.; Nakashima, Y.

    2016-11-01

    In the divertor simulation experiments in the GAMMA 10/PDX tandem mirror, pressure of the neutral gas was investigated by using a fast ionization gauge. The gauge was absolutely calibrated for hydrogen gas by using a capacitance manometer. Change of the gauge sensitivity due to the magnetic field of GAMMA 10/PDX was also evaluated. The typical gas pressure measured in detached plasma experiments was 0.1-10 Pa. The degree of plasma detachment determined from the reduction of heat flux was enhanced as the gas pressure increases. Rapid increase of the gas pressure under the plasma flow was also observed.

  3. Measurement of neutral gas pressure in the D-module of GAMMA 10/PDX by using ASDEX type fast ionization gauge.

    Science.gov (United States)

    Ichimura, K; Fukumoto, M; Islam, M M; Islam, M S; Shimizu, K; Fukui, K; Ohuchi, M; Nojiri, K; Terakado, A; Yoshikawa, M; Ezumi, N; Sakamoto, M; Nakashima, Y

    2016-11-01

    In the divertor simulation experiments in the GAMMA 10/PDX tandem mirror, pressure of the neutral gas was investigated by using a fast ionization gauge. The gauge was absolutely calibrated for hydrogen gas by using a capacitance manometer. Change of the gauge sensitivity due to the magnetic field of GAMMA 10/PDX was also evaluated. The typical gas pressure measured in detached plasma experiments was 0.1-10 Pa. The degree of plasma detachment determined from the reduction of heat flux was enhanced as the gas pressure increases. Rapid increase of the gas pressure under the plasma flow was also observed.

  4. Ionized and neutral gas in the peculiar star/cluster complex in NGC 6946

    CERN Document Server

    Efremov, Yu N; Alfaro, E J; Boomsma, R; Bastian, N; Larsen, S; Sanchez-Gil, M C; Silchenko, O K; García-Lorenzo, B; Muñoz-Tunón, C; Hodge, P W

    2007-01-01

    The characteristics of ionized and HI gas in the peculiar star/cluster complex in NGC 6946, obtained with the 6-m telescope (BTA) SAO RAS, the Gemini North telescope, and the Westerbork Synthesis Radio Telescope (WSRT), are presented. The complex is unusual as hosting a super star cluster, the most massive known in an apparently non-interacting giant galaxy. It contains a number of smaller clusters and is bordered by a sharp C-shaped rim. We found that the complex is additionally unusual in having peculiar gas kinematics. The velocity field of the ionized gas reveals a deep oval minimum, ~300 pc in size, centered 7" east of the supercluster. The Vr of the ionized gas in the dip center is 100 km/s lower than in its surroundings, and emission lines within the dip appear to be shock excited. This dip is near the center of an HI hole and a semi-ring of HII regions. The HI (and less certainly, HII) velocity fields reveal expansion, with the velocity reaching ~30 km/s at a distance about 300 pc from the center of e...

  5. HERSCHEL FAR-INFRARED SPECTRAL-MAPPING OF ORION BN/KL OUTFLOWS: SPATIAL DISTRIBUTION OF EXCITED CO, H{sub 2}O, OH, O, AND C{sup +} IN SHOCKED GAS

    Energy Technology Data Exchange (ETDEWEB)

    Goicoechea, Javier R.; Cernicharo, José; Cuadrado, Sara; Etxaluze, Mireya [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid (Spain); Chavarría, Luis [Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, E-28850 Madrid (Spain); Neufeld, David A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Vavrek, Roland [Herschel Science Center, ESA/ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691 Madrid (Spain); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Encrenaz, Pierre [LERMA, UMR 8112 du CNRS, Observatoire de Paris, École Normale Supérieure, F-75014 Paris (France); Melnick, Gary J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 66, Cambridge, MA 02138 (United States); Polehampton, Edward, E-mail: jr.goicoechea@icmm.csic.es [RAL Space, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2015-01-20

    We present ∼2' × 2' spectral-maps of Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) outflows taken with Herschel at ∼12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H{sub 2} shocked regions ''Peak 1'' and ''Peak 2'' from that of the hot core and ambient cloud. We analyze the ∼54-310 μm spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of {sup 12}CO (up to J = 48-47), H{sub 2}O, OH, {sup 13}CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L {sub FIR} ≈ 5 × 10{sup –3} ratio and a plethora of far-IR H{sub 2}O emission lines. The high-J CO and OH lines are a factor of ≈2 brighter toward Peak 1 whereas several excited H{sub 2}O lines are ≲50% brighter toward Peak 2. Most of the CO column density arises from T {sub k} ∼ 200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H{sub 2}O/CO ≲ 10{sup –2} abundance ratio. In addition, the very excited CO (J > 35) and H{sub 2}O lines reveal a hotter gas component (T {sub k} ∼ 2500 K) from faster (v {sub S} > 25 km s{sup –1}) shocks that are able to sputter the frozen-out H{sub 2}O and lead to high H{sub 2}O/CO ≳ 1 abundance ratios. The H{sub 2}O and OH luminosities cannot be reproduced by shock models that assume high (undepleted) abundances of atomic oxygen in the preshock gas and/or neglect the presence of UV radiation in the postshock gas. Although massive outflows are a common feature in other massive star-forming cores, Orion BN/KL seems more peculiar because of its higher molecular luminosities and strong outflows caused by a recent explosive event.

  6. The effects of neutral gas heating on H mode transition and maintenance currents in a 13.56 MHz planar coil inductively coupled plasma reactor

    Science.gov (United States)

    Jayapalan, Kanesh K.; Chin, Oi-Hoong

    2012-09-01

    The H mode transition and maintenance currents in a 13.56 MHz laboratory 6 turn planar coil inductively coupled plasma (ICP) reactor are simulated for low pressure argon discharge range of 0.02-0.3 mbar with neutral gas heating and at ambient temperature. An experimentally fitted 3D power evolution plot for 0.02 mbar argon pressure is also shown to visualize the effects of hysteresis in the system. Comparisons between simulation and experimental measurements show good agreement in the pressure range of 0.02-0.3 mbar for transition currents and 0.02-0.1 mbar for maintenance currents only when neutral gas heating is considered. This suggests that neutral gas heating plays a non-negligible role in determining the mode transition points of a rf ICP system.

  7. 3D Studies of Neutral and Ionised Gas and Stars in Seyfert and Inactive Galaxies

    CERN Document Server

    Mundell, C G; Schinnerer, E; Nagar, N; Haan, S; Wilcots, E; Wilson, A S; Emsellem, E; Ferruit, P; Peletier, R F; De Zeeuw, P T

    2006-01-01

    We are conducting the first systematic 3D spectroscopic imaging survey to quantify the properties of the atomic gas (HI) in a distance-limited sample of 28 Seyfert galaxies and a sample of 28 inactive control galaxies with well-matched optical properties (the VHIKINGS survey). This study aims to address the role of the host galaxy in nuclear activity and confront outstanding controversies in optical/IR imaging surveys. Early results show possible relationships between Seyfert activity and HI extent, content and the prevalence of small, nearby gas-rich dwarf galaxies (M(HI)~10^7 Msun); results will be tested via rigorous comparison with control galaxies. Initial results from our optical followup study of 15 of our galaxies using the SAURON integral field unit on the WHT suggest a possible difference between Seyfert and inactive stellar and gaseous kinematics that support the conclusion that internal kinematics of galaxies are the key to nuclear activity.

  8. Plasma and wave phenomena induced by neutral gas releases in the solar wind

    Directory of Open Access Journals (Sweden)

    H. Laakso

    Full Text Available We investigate plasma and wave disturbances generated by nitrogen (N2 gas releases from the cooling system of an IR-camera on board the Vega 1 and Vega 2 spacecraft, during their flybys of comet Halley in March 1986. N2 molecules are ionized by solar UV radiation at a rate of ~ 7 · 10-7 s-1 and give rise to a plasma cloud expanding around the spacecraft. Strong disturbances due to the interaction of the solar wind with the N+2 ion cloud are observed with a plasma and wave experiment (APV-V instrument. Three gas releases are accompanied by increases in cold electron density and simultaneous decreases of the spacecraft potential; this study shows that the spacecraft potential can be monitored with a reference sensor mounted on a short boom. The comparison between the model and observations suggests that the gas expands as an exhaust plume, and approximately only 1% of the ions can escape the beam within the first meters. The releases are also associated with significant increases in wave electric field emission (8 Hz–300 kHz; this phenomenon lasts for more than one hour after the end of the release, which is most likely due to the temporary contamination of the spacecraft surface by nitrogen gas. DC electric fields associated with the events are complex but interesting. No magnetic field perturbations are detected, suggesting that no significant diamagnetic effect (i.e. magnetic cavity is associated with these events.

    Key words. Ionosphere (planetary ionosphere – Space plasma physics (active perturbation experiments; instruments and techniques

  9. Measurements of the ion velocity distribution in an ultracold neutral plasma derived from a cold, dense Rydberg gas

    Science.gov (United States)

    Bergeson, Scott; Lyon, Mary

    2016-05-01

    We report measurements of the ion velocity distribution in an ultracold neutral plasma derived from a dense, cold Rydberg gas in a MOT. The Rydberg atoms are excited using a resonant two-step excitation pathway with lasers of 4 ns duration. The plasma forms spontaneously and rapidly. The rms width of the ion velocity distribution is determined by measuring laser-induced fluorescence (LIF) of the ions. The measured excitation efficiency is compared with a Monte-Carlo wavefunction calculation, and significant differences are observed. We discuss the conditions for blockaded Rydberg excitation and the subsequent spatial ordering of Rydberg atom domains. While the blockade interaction is greater than the Rabi frequency in portions of the atomic sample, no evidence for spatial ordering is observed. This research is supported in part by the Air Force Office of Scientific Research (Grant No. FA9950-12- 0308) and by the National Science Foundation (Grant No. PHY-1404488).

  10. Measurements of the ion velocity distribution in an ultracold neutral plasma derived from a cold, dense Rydberg gas

    CERN Document Server

    Bergeson, S D

    2016-01-01

    We report measurements of the ion velocity distribution in an ultracold neutral plasma derived from a dense, cold Rydberg gas in a MOT. The Rydberg atoms are excited using a resonant two-step excitation pathway with lasers of 4 ns duration. The plasma forms spontaneously and rapidly. The rms width of the ion velocity distribution is determined by measuring laser-induced fluorescence (LIF) of the ions. The measured excitation efficiency is compared with a Monte-Carlo wavefunction calculation, and significant differences are observed. We discuss the conditions for blockaded Rydberg excitation and the subsequent spatial ordering of Rydberg atom domains. While the blockade interaction is greater than the Rabi frequency in portions of the atomic sample, no evidence for spatial ordering is observed.

  11. The Gaia-ESO Survey: dynamics of ionized and neutral gas in the Lagoon nebula (M 8)

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Prisinzano, L.; Zwitter, T.; Bayo, A.; Kalari, V.; Jiménez-Esteban, F. M.; Costado, M. T.; Jofré, P.; Randich, S.; Flaccomio, E.; Lanzafame, A. C.; Lardo, C.; Morbidelli, L.; Zaggia, S.

    2017-08-01

    Aims: We present a spectroscopic study of the dynamics of the ionized and neutral gas throughout the Lagoon nebula (M 8), using VLT-FLAMES data from the Gaia-ESO Survey. The new data permit exploration of the physical connections between the nebular gas and the stellar population of the associated star cluster NGC 6530. Methods: We characterized through spectral fitting emission lines of Hα, [N II] and [S II] doublets, [O III], and absorption lines of sodium D doublet, using data from the FLAMES-Giraffe and UVES spectrographs, on more than 1000 sightlines toward the entire face of the Lagoon nebula. Gas temperatures are derived from line-width comparisons, densities from the [S II] doublet ratio, and ionization parameter from Hα/[N II] ratio. Although doubly-peaked emission profiles are rarely found, line asymmetries often imply multiple velocity components along the same line of sight. This is especially true for the sodium absorption, and for the [O III] lines. Results: Spatial maps for density and ionization are derived, and compared to other known properties of the nebula and of its massive stars 9 Sgr, Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing flux. The detailed velocity fields across the nebula show several expanding shells, related to the cluster NGC 6530, the O stars 9 Sgr and Herschel 36, and the massive protostar M 8East-IR. The origins of kinematical expansion and ionization of the NGC 6530 shell appear to be different. We are able to put constrains on the line-of-sight (relative or absolute) distances between some of these objects and the molecular cloud. The data show that the large obscuring band running through the middle of the nebula is being compressed by both sides, which might explain its enhanced density. We also find an unexplained large-scale velocity gradient across the entire nebula. At larger distances, the transition from ionized to neutral gas is studied using the sodium lines. Based on observations

  12. An apparatus for immersing trapped ions into an ultracold gas of neutral atoms.

    Science.gov (United States)

    Schmid, Stefan; Härter, Arne; Frisch, Albert; Hoinka, Sascha; Denschlag, Johannes Hecker

    2012-05-01

    We describe a hybrid vacuum system in which a single ion or a well-defined small number of trapped ions (in our case Ba(+) or Rb(+)) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving one-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30 cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.

  13. Electrically Detected Magnetic Resonance of Neutral Donors Interacting with a Two-Dimensional Electron Gas

    Energy Technology Data Exchange (ETDEWEB)

    Lo, C. C.; Lang, V.; George, R. E.; Morton, J. J. L.; Tyryshkin, A. M.; Lyon, A.; Bokor, J.; Schenkel, T.

    2011-04-20

    We have measured the electrically detected magnetic resonance of donor-doped silicon field-effect transistors in resonant X- (9.7 GHz) and W-band (94 GHz) microwave cavities. The two-dimensional electron gas (2DEG) resonance signal increases by two orders of magnitude from X- to W-band, while the donor resonance signals are enhanced by over one order of magnitude. Bolometric effects and spin-dependent scattering are inconsistent with the observations. We propose that polarization transfer from the donor to the 2DEG is the main mechanism giving rise to the spin resonance signals.

  14. Spatial distribution of interstellar dust in the Sun vicinity, comparison with neutral sodium-bearing gas

    CERN Document Server

    Vergely, Jean-Luc; Lallement, Rosine; Raimond, Severine

    2010-01-01

    3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the ISM itself to foreground decontamination of the CMB, or various studies of the environments of specific objects. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. We apply the best available calibration methods to a carefully screened set of stellar Stromgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6,000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion. We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds with 250 pc. We calculate the integrated extinction between the Sun and the cube boundary and compare with the total galactic extinction derived f...

  15. The supergiant shell with triggered star formation in Irr galaxy IC 2574: neutral and ionized gas kinematics

    CERN Document Server

    Egorov, O V; Moiseev, A V; Smirnov-Pinchukov, G V

    2014-01-01

    We analyse the ionized gas kinematics in the star formation regions of the supergiant shell (SGS) of the IC 2574 galaxy using observations with the Fabry-Perot interferometer at the 6-m telescope of SAO RAS; the data of the THINGS survey are used to analyze the neutral gas kinematics in the area. We perform the 'derotation' of the H-alpha and HI data cubes and show its efficiency in kinematics analysis. We confirm the SGS expansion velocity 25 km/s obtained by Walter & Brinks (1999) and conclude that the SGS is located at the far side of the galactic disc plane. We determine the expansion velocities, kinematic ages, and the required mechanical energy input rates for four star formation complexes in the walls of the SGS; for the remaining ones we give the limiting values of the above parameters. A comparison with the age and energy input of the complexes' stellar population shows that sufficient energy is fed to all HII regions except one. We discuss in detail the possible nature of this region and that of...

  16. PIC code modeling of spacecraft charging potential during electron beam injection into a background of neutral gas and plasma, part 1

    Science.gov (United States)

    Koga, J. K.; Lin, C. S.; Winglee, R. M.

    1989-01-01

    Injections of nonrelativistic electron beams from an isolated equipotential conductor into a uniform background of plasma and neutral gas were simulated using a 2-D electrostatic particle code. The ionization effects on spacecraft charging are examined by including interactions of electrons with neutral gas. The simulations show that the conductor charging potential decreases with increasing neutral background density due to the production of secondary electrons near the conductor surface. In the spacecraft wake, the background electrons accelerated towards the charged spacecraft produce an enhancement of secondary electrons and ions. Simulations run for longer times indicate that the spacecraft potential is further reduced and short wavelength beam-plasma oscillations appear. The results are applied to explain the spacecraft charging potential measured during the SEPAC experiments from Spacelab 1.

  17. Gas-phase protonation of pyridine. A variable-time neutralization-reionization and Ab initio study of pyridinium radicals.

    Science.gov (United States)

    Nguyen, V Q; Turecek, F

    1997-01-01

    Gas-phase protonation of pyridine with CH3NH3+, NH4+, t-C4H9+, H3O+ and CH5+ under thermal conditions was studied by variable-time neutralization-reionization mass spectrometry and ab initio calculations. N-Protonation was found to occur exclusively for CH3NH3+ through H3O+ and predominantly for CH5+. The calculated MP2/6-311G(2d,p) energies gave the proton affinities of N, C-2, C-3 and C-4 in pyridine as 924, 658, 686 and 637 kJ mol-1, respectively, which were in good agreement with previous experimental and theoretical results. Vertical neutralization of the N-protonated isomer (1H+) was accompanied by moderate Franck-Condon effects that deposited 20-21 kJ mol-1 in the 1H-pyridinium radicals (1H) formed. 1H was calculated by UMP2/6-311G(2d,p) and B3LYP/6-311G(2d,p) to be a bound species in its ground electronic state. A substantial fraction of stable 1H was detected in the spectra, which depended on the precursor ion internal energy. Deuterium labeling showed a specific loss of the N-bound hydrogen or deuterium in the radicals. The specificity increased with increasing internal energy in the radicals and decreasing contribution of ion dissociations following reionization. Variable-time measurements established specific loss of the N-bound deuterium also in dissociating low-energy 1D. Loss of hydrogen from 1H+ cations following reionization was highly endothermic and was accompanied by rearrangements that partially scrambled the ring hydrogens.

  18. Disks and Outflows

    Science.gov (United States)

    Rodriguez, L. F.

    2002-05-01

    The presence of disks and outflows characterizes the earliest stages of stellar evolution. I will review recent results that exemplify how the radio observations have become powerful tools in the study of these extremely young objects. Binarity and multiplicity seem to be factors that we are only starting to understand. Outflows are now seen as laboratories for the chemistry of shocked regions. Finally, the efforts to extend the paradigm for low-mass stellar formation to more massive protostars can be tested critically in the radio wavelengths. I acknowledge the support from CONACyT, Mexico.

  19. Neutral current quasielastic (anti)neutrino scattering beyond the Fermi gas model at MiniBooNE and BNL kinematics

    CERN Document Server

    Ivanov, M V; Barbaro, M B; Giusti, C; Meucci, A; Caballero, J A; Gonzalez-Jimenez, R; de Guerra, E Moya; Udias, J M

    2015-01-01

    Neutral current quasielastic (anti)neutrino scattering cross sections on a $^{12}$C target are analyzed using a realistic spectral function $S(p,E)$ that gives a scaling function in accordance with the ($e,e'$) scattering data. The spectral function accounts for the nucleon-nucleon (NN) correlations by using natural orbitals (NOs) from the Jastrow correlation method and has a realistic energy dependence. The standard value of the axial mass $M_A= 1.032$ GeV is used in all calculations. The role of the final-state interaction (FSI) on the spectral and scaling functions, as well as on the cross sections is accounted for. A comparison of the calculations with the empirical data of the MiniBooNE and BNL experiments is performed. Our results are analyzed in comparison with those when NN correlations are not included, and also with results from other theoretical approaches, such as the relativistic Fermi gas (RFG), the relativistic mean field (RMF), the relativistic Green's function (RGF), as well as with the Super...

  20. A high order cell-centered semi-Lagrangian scheme for multi-dimensional kinetic simulations of neutral gas flows

    CERN Document Server

    Güçlü, Yaman

    2013-01-01

    The term `Convected Scheme' (CS) refers to a family of algorithms, most usually applied to the solution of Boltzmann's equation, which uses a method of characteristics in an integral form to project an initial cell forward to a group of final cells. As such the CS is a `forward-trajectory' semi-Lagrangian scheme. For multi-dimensional simulations of neutral gas flows, the cell-centered version of this semi-Lagrangian (CCSL) scheme has advantages over other options due to its implementation simplicity, low memory requirements, and easier treatment of boundary conditions. The main drawback of the CCSL-CS to date has been its high numerical diffusion in physical space, because of the 2$^{\\text{nd}}$ order remapping that takes place at the end of each time step. By means of a Modified Equation Analysis, it is shown that a high order estimate of the remapping error can be obtained a priori, and a small correction to the final position of the cells can be applied upon remapping, in order to achieve full compensatio...

  1. He Bulge Detection by MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS) in the Upper Atmosphere of Mars

    Science.gov (United States)

    Elrod, Meredith; Bougher, Stephen; Benna, Mehdi; Yelle, Roger; Jakosky, Bruce; Bell, Jared; Mahaffy, Paul; Stone, Shane

    2016-07-01

    Studies of the Venusian atmospheres have demonstrated enhanced He densities at high latitudes and on the night-side detections. To determine if Mars has a similar enhanced He 'bulge' in the same region, we compared several periapsis passes from night to dayside. The first six weeks of the MAVEN prime mission had periapsis at high latitudes on the night-side, followed by the next three months at mid latitudes on the dayside moving to low latitudes on the night-side. In addition to its normal orbit, which has a periapsis of approximately 150 km, MAVEN conducts a few deep dip orbits where the spacecraft has a periapsis closer to 125km. The first deep dip was at dusk at mid latitudes, the second at noon at the equator, with the third going from dawn to night in the southern hemisphere. Initial analysis of the Neutral Gas and Ion Mass Spectrometer (NGIMS) closed source data from all orbits with good pointing revealed an enhanced He density on the night-side orbits and a decreased He density on the dayside. This enhancement of He demonstrates a bulge at Mars that will continue to be explored over the course of the mission.

  2. Kinetics fermentation and gas production of the neutral detergent-soluble fraction of fresh forage, silage and hay of Avena sativa

    Directory of Open Access Journals (Sweden)

    V. Piccolo

    2011-03-01

    Full Text Available Neutral detergent treatment to evaluate the structural polysaccharides (NDF removes soluble sugars, pectin substances, starch and the non-carbohydrate fraction (Van Soest, 1991. Despite the widely recognized importance of neutral detergent-soluble carbohydrates (NDS in the early stages of forage digestion, little is known about their digestion kinetics because most in vitro methods have studied the disappearance of insoluble cell wall components. However, knowledge of the degradation characteristics of both fractions is very important to formulate balanced diets for high-yielding animals. Using the in vitro gas production system........

  3. Feedback from Mass Outflows in Nearby Active Galactic Nuclei. II. Outflows in the Narrow-Line Region of NGC 4151

    CERN Document Server

    Crenshaw, D M; Kraemer, S B; Schmitt, H R

    2014-01-01

    We present a detailed study of AGN feedback in the narrow-line region (NLR) of the Seyfert 1 galaxy NGC 4151. We illustrate the data and techniques needed to determine the mass outflow rate and kinetic luminosity of the outflowing ionized gas as a function of position in the NLR. We find that the mass outflow rate peaks at a value of 3 solar masses per year at a distance of 70 pc from the central supermassive black hole (SMBH), which is about 10 times the outflow rate coming from inside 13 pc, and 230 times the mass accretion rate inferred from the bolometric luminosity of NGC 4151. Thus, most of the outflow must arise from "in situ" acceleration of ambient gas throughout the NLR. The kinetic luminosity peaks at 90 pc and drops rapidly thereafter, indicating that most of the kinetic energy is deposited within about 100 pc from the SMBH. Both values exceed the mass outflow rate and kinetic luminosity determined for the UV/X-ray absorber outflows in NGC 4151, indicating the importance of NLR outflows in providi...

  4. Mediterranean Outflow Mixing Dynamics

    Science.gov (United States)

    1993-02-01

    tugal. G. Parrnlla is at Instituto EspaWol Oceanografia , Fig. 2A. [Adapted from (36)] (C) The maximum observed velocity of outflow currents in the eastern...its sur- Oceanografia Fisica del Estrecho de Gibraltar, J. of Mediterranean water that we observed at the roundings (34) and retains its chemical L

  5. Suppression of galactic outflows by cosmological infall and circumgalactic medium

    CERN Document Server

    Singh, Priyanka; Bagla, Jasjeet S; Nath, Biman B

    2016-01-01

    We investigate the relative importance of two galactic outflow suppression mechanisms : a) Cosmological infall of the intergalactic gas onto the galaxy, and b) the existence of a hot circumgalactic medium (CGM). Considering only radial motion, the infall reduces the speed of outflowing gas and even halts the outflow, depending on the mass and redshift of the galaxy. For star forming galaxies there exists an upper mass limit beyond which outflows are suppressed by the gravitational field of the galaxy. We find that infall can reduce this upper mass limit approximately by a factor of two (independent of the redshift). Massive galaxies ($\\gtrsim 10^{12} M_{\\odot}$) host large reservoir of hot, diffuse CGM around the central part of the galaxy. The CGM acts as a barrier between the infalling and outflowing gas and provides an additional source of outflow suppression. We find that at low redshifts ($z\\lesssim3.5$), the CGM is more effective than the infall in suppressing the outflows. Together, these two processes...

  6. GALAXY OUTFLOWS WITHOUT SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Sur, Sharanya [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore 560034 (India); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 876004, Tempe-85287 (United States); Ostriker, Eve C., E-mail: sharanya.sur@iiap.res.in, E-mail: sharanya.sur@asu.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-02-10

    High surface density, rapidly star-forming galaxies are observed to have ≈50–100 km s{sup −1} line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s{sup −1}, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M{sub ⊙} yr{sup −1} kpc{sup −2}. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

  7. Outflows of stars due to quasar feedback

    CERN Document Server

    Zubovas, Kastytis; Sazonov, Sergey; Sunyaev, Rashid

    2013-01-01

    Quasar feedback outflows are commonly invoked to drive gas out of galaxies in the early gas-rich epoch to terminate growth of galaxies. Here we present simulations that show that AGN feedback may drive not only gas but also stars out of their host galaxies under certain conditions. The mechanics of this process is as following: (1) AGN-driven outflows accelerate and compress gas filling the host galaxy; (2) the accelerated dense shells become gravitationally unstable and form stars on radial trajectories. For the spherically symmetric initial conditions explored here, the black hole needs to exceed the host's M_sigma mass by a factor of a few to accelerate the shells and the new stars to escape velocities. We discuss potential implications of these effects for the host galaxies: (i) radial mixing of bulge stars with the rest of the host; (ii) contribution of quasar outflows to galactic fountains as sources of high-velocity clouds; (iii) wholesale ejection of hyper velocity stars out of their hosts, giving ris...

  8. Analysis of neutral nitromusks in incenses by capillary electrophoresis in organic solvents and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Gotti, Roberto; Fiori, Jessica; Mancini, Francesca; Cavrini, Vanni

    2005-09-01

    Nitromusks used as fragrances in a variety of personal-care products, cleansers, and domestic deodorants, including incense sticks, are neutral nitro aromatic compounds; some of these have been reported as photosensitizers. In this work, their analysis was performed by capillary electrophoresis (CE) in a methanol-based background electrolyte (BGE). In particular, a 10 mM solution of citric acid in methanol was used; under these conditions the strong suppression of the electroosmotic flow favored the use of negatively charged surfactants as additives for the anodic migration of the studied analytes. To this end, sodium taurodeoxycholate (TDC) was supplemented at high concentration (190 mM) to the organic background electrolyte (BGE), showing strong indication of the ability to give micelle-like aggregates. Since nitromusks are characterized by the presence of a nitroaromatic ring with low charge density, their association with TDC aggregates can be ascribed to donor-acceptor interactions. Separation of musk xylene, musk ketone, and the banned musk moskene and musk ambrette was obtained under full nonaqueous BGE; the addition of relatively small water percentages (15% v/v) was found to be useful in improving the separation of pairs of adjacent peaks. Under optimized conditions (190 mM sodium TDC in methanol-water, 85-15 v/v containing citric acid 10 mM) the system was applied to the analysis of nitromusks in incense sticks extracted with methanol. The results were compared with those obtained by the analysis of the same samples using gas chromatography with mass detector. The expected different selectivity of separation obtained using the two techniques can be useful in the unambiguous determination of the analytes; furthermore, a substantial accord of the preliminary quantitative results achieved with the two methods was assumed as the confirmation of the potential reliability of CE performed with high percentage of organic solvent.

  9. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  10. Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei; Wofford, Aida; Lundgren, Britt

    2014-01-01

    We report on a sample of 51 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We calculate Si II kinematics and densities arising from warm gas entrained in galactic outflows. We use multi-wavelength ancillary data to estimate stellar masses (M$_\\ast$), star-formation rates (SFR), and morphologies. We derive significant correlations between outflow velocity and SFR$^{\\sim 0.1}$, M$_\\ast^{\\sim 0.1}$ and v$_\\text{circ}^{\\sim 1/2}$. Some mergers drive outflows faster than these relations prescribe, launching the outflow faster than the escape velocity. Calculations of the mass outflow rate reveal strong scaling with SFR$^{\\sim 1/2}$ and M$_\\ast^{\\sim 1/2}$. Additionally, mass-loading efficiency factors (mass outflow rate divided by SFR) scale approximately as M$_\\ast^{-1/2}$. Both the outflow velocity and mass-loading scaling suggest that these outflows are powered by supernovae, with only 0.7% of the total supernovae energy converted into the kinetic energ...

  11. Galaxy Outflows Without Supernovae

    CERN Document Server

    Sur, Sharanya; Ostriker, Eve C

    2016-01-01

    High surface density, rapidly star-forming galaxies are observed to have $\\approx 50-100\\,{\\rm km\\,s^{-1}}$ line-of-sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly-compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds $\\approx 35\\,{\\rm km\\...

  12. The role of cosmic ray pressure in accelerating galactic outflows

    CERN Document Server

    Simpson, Christine M; Marinacci, Federico; Pfrommer, Christoph; Springel, Volker; Glover, Simon C O; Clark, Paul C; Smith, Rowan J

    2016-01-01

    We study the formation of galactic outflows from supernova explosions (SNe) with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SNe placement and energy feedback, including cosmic rays (CR), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows...

  13. Collapse and Outflow Towards an Integrated Theory of Star Formation

    CERN Document Server

    Pudritz, R E; Ouyed, R

    1997-01-01

    Observational advances over the last decade reveal that star formation is associated with the simultaneous presence of gravitationally collapsing gas, bipolar outflow, and an accretion disk. Two theoretical views of star formation suppose that either stellar mass is determined from the outset by gravitational instability, or by the outflow which sweeps away the collapsing envelope of initially singular density distributions. Neither picture appears to explain all of the facts. This contribution examines some of the key issues facing star formation theory.

  14. X-Ray/Ultraviolet Observing Campaign of the Markarian 279 Active Galactic Nucleus Outflow: a close look at the absorbing/emitting gas with Chandra-LETGS

    CERN Document Server

    Costantini, E; Arav, N; Kriss, G A; Steenbrugge, K C; Gabel, J R; Verbunt, F; Behar, E; Gaskell, C M; Korista, K T; Proga, D; Quijano, J K; Scott, J E; Klimek, E S; Hedrick, C H

    2006-01-01

    We present a Chandra-LETGS observation of the Seyfert 1 galaxy Mrk 279. This observation was carried out simultaneously with HST-STIS and FUSE, in the context of a multiwavelength study of this source. The Chandra pointings were spread over ten days for a total exposure time of ~360 ks. The spectrum of Mrk279 shows evidence of broad emission features, especially at the wavelength of the OVII triplet. We quantitatively explore the possibility that this emission is produced in the broad line region (BLR). We modeled the broad UV emission lines seen in the FUSE and HST-STIS spectra following the ``locally optimally emitting cloud" approach. We find that the X-ray lines luminosity derived from the best fit BLR model can match the X-ray features, suggesting that the gas producing the UV lines is sufficient to account also for the X-ray emission. The spectrum is absorbed by ionized gas whose total column density is ~5x10^{20} cm^{-2}. The absorption spectrum can be modeled by two distinct gas components (log xi ~ 0...

  15. Energy- and momentum-conserving AGN feedback outflows

    CERN Document Server

    Zubovas, Kastytis

    2014-01-01

    It is usually assumed that outflows from luminous AGN are either in the energy-conserving (non-radiative) or in the momentum-conserving (radiative) regime. We show that in a non-spherical geometry the effects of both regimes may manifest at the same time, and that it is the momentum of the outflow that sets the $M_{\\rm BH}-\\sigma$ relation. Considering an initially elliptical distribution of gas in the host galaxy, we show that a non-radiative outflow opens up a wide ``escape route'' over the paths of least resistance. Most of the outflow energy escapes in that direction. At the same time, in the directions of higher resistance, the ambient gas is affected mainly by the incident momentum from the outflow. Quenching SMBH growth requires quenching gas delivery along the paths of highest resistance, and therefore, it is the momentum of the outflow that limits the black hole growth. We present an analytical argument showing that such energy-conserving feedback bubbles driving leaky ambient shells will terminate S...

  16. Earth’s Interaction Region: Plasma-Neutral Interactions in the Weakly Ionized gas of Earth’s High Latitude Upper Atmosphere

    Science.gov (United States)

    Thayer, Jeffrey; Hsu, Vicki

    2015-04-01

    The high-latitude regions of Earth’s upper atmosphere are strongly influenced by plasma-neutral interactions. These interactions couple electrodynamic processes of the ionosphere with hydrodynamic processes of the more abundant thermosphere neutral gas, consequently connecting the high-latitude upper atmosphere to distant regions of the geoplasma environment. This produces a complex spatial and temporal interplay of competing processes that results in a myriad of physical and chemical responses and a rich array of neutral and plasma morphologies that constitute the high-latitude thermosphere and ionosphere. The altitude extent from the lower thermosphere to the upper ionosphere (90km - 1000km) can be considered Earth’s space-atmosphere interaction region - likened to the solar chromosphere’s interaction region where radiative processes and hydrodynamic waves from the dense lower atmosphere produce a cold lower boundary that quickly transitions over a few 100 kilometers to neutral and plasma temperatures that are five times hotter. A thousand or more kilometers further in altitude, Earth's upper atmosphere becomes a hot, collisionless, geomagnetically controlled protonosphere whose neutral and plasma population originates from the thermosphere and ionosphere. A grand challenge in the study of Earth’s interaction region is how the collision-dominated thermosphere/ionosphere system exchanges energy, mass and momentum with the collisionless magnetosphere. This talk will focus primarily on collision-dominated processes of the high-latitude ionosphere and the electromagnetic energy transfer processes that lead to frictional heating of ions and neutrals, and plasma instability phenomenon that leads to extreme electron heating. Observations of the ionosphere response to these processes will be illustrated using incoherent scatter radar measurements. Relevance to the solar chromosphere will be identified where appropriate and outstanding issues in Earth

  17. ALMA OBSERVATIONS OF THE HH 46/47 MOLECULAR OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Arce, Hector G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Mardones, Diego; Garay, Guido [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Corder, Stuartt A. [Joint ALMA Observatory, Av. Alonso de Cordova 3107, Vitacura, Santiago (Chile); Noriega-Crespo, Alberto [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Raga, Alejandro C. [Instituto de Ciencias Nucleares, UNAM, Ap. 70-543, 04510 D.F. (Mexico)

    2013-09-01

    The morphology, kinematics, and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29 point mosaic, covering the two lobes at an angular resolution of about 3'', detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model describes the observed structures in the position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a collimated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show gradients where the velocity increases toward the outflow axis, inconsistent with outflow rotation. Additionally, we find evidence for the existence of a small outflow driven by a binary companion.

  18. Core excitation and decay in rare gas mono- and multilayers on a metal surface: screening, deexcitation, and desorption of neutrals and ions

    Science.gov (United States)

    Rocker, G.; Feulner, P.; Scheuerer, R.; Zhu, L.; Menzel, D.

    1990-06-01

    In order to investigate the modification of excitation and decay of core holes by condensation and adsorption in the simplest possible cases, as well as the coupling to atomic motion, we have studied the Ar2p and Kr3d excitation regions in Ar and Kr mono- and multilayers on Ru(001). Using synchrotron radiation from BESSY (Berlin), total and Auger electron yields and yields of desorbing ions and neutrals, as function of photon energy, as well as decay electron spectra for specific primary excitations have been measured. The main results are: Multilayers: Energies for resonant core excitations are shifted to higher values by 0.6 to 1 eV compared to free atoms; for Kr, surface (smaller shifts) and bulk excitations can be distinguished. Autoionization and normal Auger spectra are clearly different, as in the gas phase. Besides desorption of neutral atoms as in the valence region, singly and doubly charged ions as well as ionic clusters are desorbed. Monolayers: The shift of resonant excitation energies relative to the gas phase is smaller than for condensed layers. Decay spectra for resonant and non-resonant excitations are identical, as for strongly coupled chemisorbates, proving that charge exchange with the metal is fast compared to core decay. As in the valence region, only neutral atoms desorb. The results shed light on the screening and charge transfer behaviour and on the mechanisms of stimulated desorption which are operative in them.

  19. Illuminating gas inflows/outflows in the MUSE deepest fields: Lyα nebulae around forming galaxies at z ≃ 3.3

    Science.gov (United States)

    Vanzella, E.; Balestra, I.; Gronke, M.; Karman, W.; Caminha, G. B.; Dijkstra, M.; Rosati, P.; De Barros, S.; Caputi, K.; Grillo, C.; Tozzi, P.; Meneghetti, M.; Mercurio, A.; Gilli, R.

    2017-03-01

    We report the identification of extended Lyα nebulae at z ≃ 3.3 in the Hubble Ultra Deep Field (HUDF, ≃40 kpc × 80 kpc) and behind the Hubble Frontier Field galaxy cluster MACSJ0416 (≃40 kpc), spatially associated with groups of star-forming galaxies. VLT/MUSE integral field spectroscopy reveals a complex structure with a spatially varying double-peaked Lyα emission. Overall, the spectral profiles of the two Lyα nebulae are remarkably similar, both showing a prominent blue emission, more intense and slightly broader than the red peak. From the first nebula, located in the HUDF, no X-ray emission has been detected, disfavouring the possible presence of active galactic nuclei. Spectroscopic redshifts have been derived for 11 galaxies within 2 arcsec from the nebula and spanning the redshift range 1.037 masses per year. A possible scenario is that of a group of young, star-forming galaxies emitting ionizing radiation that induces Lyα fluorescence, therefore revealing the kinematics of the surrounding gas. Also Lyα powered by star formation and/or cooling radiation may resemble the double-peaked spectral properties and the morphology observed here. If the intense blue emission is associated with inflowing gas, then we may be witnessing an early phase of galaxy or a proto-cluster (or group) formation.

  20. The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

    CERN Document Server

    Husemann, B; Sánchez, S F; Jahnke, K

    2012-01-01

    (Abridged) We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 QSOs observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data. We identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of HII regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is 10kpc at a median nuclear [OIII] luminosity of log(L([OIII])/[erg/s])=42.7+-0.15. We show that the ENLR sizes are least a factor of 2 larger than determined with HST, but are consistent with those of recentl...

  1. Searching for Brown Dwarf Outflows

    CERN Document Server

    Whelan, E T; Bacciotti, F; Randich, S; Natta, A

    2009-01-01

    As outflow activity in low mass protostars is strongly connected to ac- cretion it is reasonable to expect accreting brown dwarfs to also be driving out- flows. In the last three years we have searched for brown dwarf outflows using high quality optical spectra obtained with UVES on the VLT and the technique of spectro-astrometry. To date five brown dwarf outflows have been discovered. Here the method is discussed and the results to date outlined.

  2. First Detection of A Sub-kpc Scale Molecular Outflow in the Starburst Galaxy NGC 3628

    CERN Document Server

    Tsai, An-Li; Kong, Albert K H; Matsumoto, Hironori; Kohno, Kotaro

    2012-01-01

    We successfully detected a molecular outflow with a scale of 370-450 pc in the central region of the starburst galaxy NGC 3628 through deep CO(1-0) observations by using the Nobeyama Millimeter Array (NMA). The mass of the outflowing molecular gas is ~2.8x10^7 M_sun, and the outflow velocity is ~90(+/-10) km s^{-1}. The expansion timescale of the outflow is 3.3-6.8 Myr, and the molecular gas mass flow rate is 4.1-8.5 M_sun yr^{-1}. It requires mechanical energy of (1.8-2.8)x10^{54} erg to create this sub-kpc scale molecular outflow. In order to understand the evolution of the molecular outflow, we compare the physical properties between the molecular outflow observed from our NMA CO(1-0) data and the plasma gas from the soft X-ray emission of the Chandra X-ray Observatory (CXO) archival data. We found that the distribution between the molecular outflow and the strong plasma outflow seems to be in a similar region. In this region, the ram pressure and the thermal pressure of the plasma outflow are 10^{-(8-10)}...

  3. SOFIA observations of CO(12-11) emission along the L1157 bipolar outflow

    CERN Document Server

    Eislöffel, Jochen; Güsten, Rolf; Wiesemeyer, Helmut; Gusdorf, Antoine

    2012-01-01

    Carbon monoxide is an excellent tracer of the physical conditions of gas in molecular outflows from young stars. To understand the outflow mechanism we need to investigate the origin of the molecular emission and the structure and interaction of the outflowing molecular gas. Deriving the physical parameters of the gas will help us to trace and understand the various gas components in the flow. We observed CO(12-11) line emission at various positions along the L1157 bipolar outflow with GREAT aboard SOFIA. Comparing these new data with CO(2-1), we find basically constant line ratios along the outflow and even at the position of the source. These line ratios lead us to estimates of 10^5 to 10^6 cm^-3 for the gas density and 60 to 100 K for the gas temperature of the outflowing gas. The constrained density and temperature values indicate that we are mostly tracing a low-velocity gas component everywhere along the outflow, which is intermediate between the already known cold gas component, which gets entrained in...

  4. Characterization of Molecular Outflows in The Substellar Domain

    CERN Document Server

    Phan-Bao, Ngoc; Ho, Paul T P; Dang-Duc, Cuong; Li, Di

    2014-01-01

    We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J=2-1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M_J, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36 degrees. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9x10^-6 M_Sun to 2.9x10^-5 M_Sun and an outflow mass-loss rate from 2.7x10^-9 M_Sun yr^-1 to 4.1x10^-8 M_Su...

  5. Determining the Spatially Resolved Mass Outflow Rate in Markarian 573

    Science.gov (United States)

    Revalski, Mitchell; Crenshaw, D. Michael; Fischer, Travis C.; Kraemer, Steven B.; Schmitt, Henrique R.

    2017-01-01

    We report on current progress in calculating the narrow line region (NLR) mass outflow rate in the Seyfert 2 galaxy Markarian 573. Our goal is to determine the mass outflow rate as a function of distance from the nucleus in 10 nearby Active Galactic Nuclei (AGN) with spatially resolved NLRs. These nearby AGN allow us to study the feeding and feedback of supermassive black holes (SMBHs) that may play an important role in understanding large scale structure, enrichment of the interstellar medium, and coevolution of SMBHs with their host galaxies. Utilizing archival spectra from the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) we measured emission line ratios from a wide range of ionized species. Next we used the line ratios to find a reddening correction and determined the physical conditions in the ionized gas using the photoionization code Cloudy. Specifically, we derived the mass of the ionized gas and then estimate the total mass outside of the spectral slit using HST [O III] images. Combined with kinematic models of the outflows we will determine the mass outflow rate and kinetic luminosity as a function of distance from the central AGN. Ultimately, we aim to determine if NLR outflows are effective in regulating AGN feedback by comparing our observed outflow rates with theoretical models.

  6. Identifying the outflow driving sources in Orion-KL

    CERN Document Server

    Beuther, H

    2008-01-01

    The enigmatic outflows of the Orion-KL region have raised discussions about their potential driving sources for several decades. Here, we present C18O(2-1) observations combined from the Submillimeter Array and the IRAM30m telescope. The molecular gas is associated on large scales with the famous northwest-southeast high-velocity outflow whereas the high-velocity gas on small spatial scales traces back to the recently identified submm source SMA1. Therefore, we infer that SMA1 may host the driving source of this outflow. Based on the previously published thermal and maser SiO data, source I is the prime candidate to drive the northeast-southwest low-velocity outflow. The source SMA1 is peculiar because it is only detected in several submm wavelength bands but neither in the infrared nor cm regime. We discuss that it may be a very young intermediate- to high-mass protostar. The estimated outflow masses are high whereas the dynamical time-scale of the outflow is short of the order 10^3yrs.

  7. Detection of hot, metal-enriched outflowing gas around $z\\approx\\,$2.3 star-forming galaxies in the Keck Baryonic Structure Survey

    CERN Document Server

    Turner, Monica L; Steidel, Charles C; Rudie, Gwen C; Strom, Allison L

    2014-01-01

    We use quasar absorption lines to study the physical conditions in the circumgalactic medium of redshift $z\\approx 2.3$ star-forming galaxies taken from the Keck Baryonic Structure Survey (KBSS). In Turner et al. 2014 we used the pixel optical depth technique to show that absorption by HI and the metal ions OVI, NV, CIV, CIII and SiIV is strongly enhanced within $|\\Delta v|\\lesssim170$ km/s and projected distances $|d|\\lesssim180$ proper kpc from sightlines to the background quasars. Here we demonstrate that the OVI absorption is also strongly enhanced at fixed HI, CIV, and SiIV optical depths, and that this enhancement extends out to $\\sim350$ km/s. At fixed HI the increase in the median OVI optical depth near galaxies is 0.3-0.7 dex and is detected at 2--3-$\\sigma$ confidence for all seven HI bins that have $\\log_{10}\\tau_{\\rm HI}\\ge-1.5$. We use ionisation models to show that the observed strength of OVI as a function of HI is consistent with enriched, photoionised gas for pixels with $\\tau_{\\rm HI}\\gtrsim...

  8. Illuminating gas in-/outflows in the MUSE deepest fields: discovery of Ly-alpha nebulae around forming galaxies at z~3.3

    CERN Document Server

    Vanzella, E; Gronke, M; Karman, W; Caminha, G B; Dijkstra, M; Rosati, P; De Barros, S; Caputi, K; Grillo, C; Tozzi, P; Meneghetti, M; Mercurio, A; Gilli, R

    2016-01-01

    We report on the discovery of extended Ly-alpha nebulae at z~3.3 in the Hubble Ultra Deep Field (HUDF, ~ 40 kpc X 80 kpc) and behind the Hubble Frontier Fields galaxy cluster MACSJ0416 (~ 40kpc), spatially associated with groups of star-forming galaxies. VLT/MUSE integral field spectroscopy reveals a complex structure with a spatially-varying double peaked Ly-alpha emission. Overall, the spectral profiles of the two Ly-alpha nebulae are remarkably similar, both showing a prominent blue emission, more intense and slightly broader than the red peak. From the first nebula, located in the HUDF, no X-ray emission has been detected, disfavoring the possible presence of AGNs. Spectroscopic redshifts have been derived for 11 galaxies within two arcsec from the nebula and spanning the redshift range 1.037gas. In both systems, the associated galaxies reveal possible intense rest-frame-optic...

  9. The role of the ''Neutral Service Provider'' in the liberalised gas market; Die Rolle des ''Neutral Service Provider'' im liberalisierten Erdgasmarkt

    Energy Technology Data Exchange (ETDEWEB)

    Peper, F.; Greverath, I. [Viavera GmbH Dortmund (Germany)

    2002-07-01

    The ongoing liberalisation of European gas markets forces network operators as well as retail companies to implement new processes. This article focuses on the challenges for network operators. In this context the potential for 'Neutral Service Providers (NSP)' is discussed. Based on sample TPA processes the interaction between the NSP and the network operator is explored. The authors conclude that for many market participants the outsourcing of TPA processes to a specialized service provider has the potential to deliver significant benefits. (orig.) [German] Die fortschreitende Liberalisierung der europaeischen Erdgasmaerkte stellt die Netz- sowie die Vertriebsgesellschaften vor staendig wachsende Anforderungen. Dabei wird in diesem Artikel der Schwerpunkt auf die Komplexitaet der Aufgaben insbesondere fuer Netzbetreiber gelegt. In diesem Zusammenhang werden die hieraus resultierenden Marktchancen fuer neue Dienstleistungsunternehmen, die sogenannten 'Neutral Service Provider' (NSP) eroertert. Anhand eines Prozessbeispiels wird die Interaktion zwischen NSP und den von ihm betreuten Netzbetreibern diskutiert. Die Autoren kommen zu dem Schluss, dass fuer viele Marktteilnehmer die Auslagerung bestimmter Unternehmensaktivitaeten im Zusammenhang mit der Bewaeltigung des Netzzugangs Dritter an einen spezialisierten Dienstleister mit erheblichen Vorteilen verbunden ist. (orig.)

  10. Large-scale HI in nearby radio galaxies : segregation in neutral gas content with radio source size

    NARCIS (Netherlands)

    Emonts, B. H. C.; Morganti, R.; Oosterloo, T. A.; van der Hulst, J. M.; van Moorsel, G.; Tadhunter, C. N.

    2007-01-01

    We present results of a study of neutral hydrogen ( HI) in a complete sample of nearby non-cluster radio galaxies. We find that radio galaxies with large amounts of extended HI (M-HI >= 109 M-circle dot) all have a compact radio source. The host galaxies of the more extended radio sources, all of Fa

  11. Morphology, luminescence, and electrical resistance response to H 2 and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte

    Science.gov (United States)

    Volciuc, O.; Monaico, E.; Enachi, M.; Ursaki, V. V.; Pavlidis, D.; Popa, V.; Tiginyanu, I. M.

    2010-11-01

    Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1 × 10 17 cm -3 and 1 × 10 18 cm -3 in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H 2 and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.

  12. Morphology, luminescence, and electrical resistance response to H{sub 2} and CO gas exposure of porous InP membranes prepared by electrochemistry in a neutral electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Volciuc, O.; Monaico, E.; Enachi, M. [National Center for Materials Study and Testing, Technical University of Moldova, Bd. Stefan cel Mare 168, Chisinau 2004 (Moldova, Republic of); Ursaki, V.V., E-mail: ursaki@yahoo.com [Institute of Applied Physics, Academy of Sciences of Moldova, Academy str. 5, Chisinau 2028 (Moldova, Republic of); Pavlidis, D. [Fachgebiet fuer Hoechstfrequenzelektronik, Technische Universitaet Darmstadt, Merckstrasse 25, Darmstadt 64283 (Germany); Popa, V. [National Center for Materials Study and Testing, Technical University of Moldova, Bd. Stefan cel Mare 168, Chisinau 2004 (Moldova, Republic of); Fachgebiet fuer Hoechstfrequenzelektronik, Technische Universitaet Darmstadt, Merckstrasse 25, Darmstadt 64283 (Germany); Tiginyanu, I.M. [National Center for Materials Study and Testing, Technical University of Moldova, Bd. Stefan cel Mare 168, Chisinau 2004 (Moldova, Republic of); Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Academy str. 3/3, Chisinau 2028 (Moldova, Republic of)

    2010-11-15

    Porous InP membranes have been prepared by anodization of InP wafers with electron concentration of 1 x 10{sup 17} cm{sup -3} and 1 x 10{sup 18} cm{sup -3} in a neutral NaCl electrolyte. The internal surfaces of pores in some membranes were modified by electrochemical deposition of gold in a pulsed voltage regime. Photoluminescence and photosensitivity measurements indicate efficient light trapping and porous surface passivation. The photoluminescence and electrical resistivity of the membranes are sensitive to the adsorption of H{sub 2} and CO gas molecules. These properties are also influenced by the deposition of Au nanoparticles inside the pores.

  13. Jet driven molecular outflows in Orion

    CERN Document Server

    Rodríguez-Franco, A; Wilson, T L

    1999-01-01

    We present high sensitivity and high angular resolution images of the high velocity (vLSR>30kms^-1) CO emission in the J=1-0 and J=2-1 lines of the Orion KL region. These results reveal the morphology of the high-velocity CO emission at the most extreme velocities. High velocity emission have been only detected in two regions: BN/KL (IRc2/I) and Orion-S. The Orion-S region contains a very young (dynamical age of 10^3years), very fast (~110kms^-1) and very compact (<0.16pc) bipolar outflow. From the morphology of the high-velocity gas we estimate that the position of the powering source must be ~20'' north of FIR4. For the IRc2/I molecular outflow the morphology of the moderate velocity (<60kms^-1) gas shows a weak bipolarity around IRc2/I. The gas at the most extreme velocities does not show any bipolarity around IRc2/I, if any, it is found ~30'' north from these sources. The blue and redshifted gas at moderate velocities shows similar spatial distribution with a systematic trend for the size of the hig...

  14. Characterization of molecular outflows in the substellar domain

    Energy Technology Data Exchange (ETDEWEB)

    Phan-Bao, Ngoc; Dang-Duc, Cuong [Department of Physics, International University-Vietnam National University HCM, Block 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City (Viet Nam); Lee, Chin-Fei; Ho, Paul T. P. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Di, E-mail: pbngoc@hcmiu.edu.vn, E-mail: pbngoc@asiaa.sinica.edu.tw [National Astronomical Observatories, Chinese Academy of Science, Chaoyang District Datun Rd A20, Beijing (China)

    2014-11-01

    We report here our latest search for molecular outflows from young brown dwarfs and very low-mass stars in nearby star-forming regions. We have observed three sources in Taurus with the Submillimeter Array and the Combined Array for Research in Millimeter-wave Astronomy at 230 GHz frequency to search for CO J = 2 → 1 outflows. We obtain a tentative detection of a redshifted and extended gas lobe at about 10 arcsec from the source GM Tau, a young brown dwarf in Taurus with an estimated mass of 73 M {sub J}, which is right below the hydrogen-burning limit. No blueshifted emission around the brown dwarf position is detected. The redshifted gas lobe that is elongated in the northeast direction suggests a possible bipolar outflow from the source with a position angle of about 36°. Assuming that the redshifted emission is outflow emission from GM Tau, we then estimate a molecular outflow mass in the range from 1.9 × 10{sup –6} M {sub ☉} to 2.9 × 10{sup –5} M {sub ☉} and an outflow mass-loss rate from 2.7 × 10{sup –9} M {sub ☉} yr{sup –1} to 4.1 × 10{sup –8} M {sub ☉} yr{sup –1}. These values are comparable to those we have observed in the young brown dwarf ISO-Oph 102 of 60 M {sub J} in ρ Ophiuchi and the very low-mass star MHO 5 of 90 M {sub J} in Taurus. Our results suggest that the outflow process in very low-mass objects is episodic with a duration of a few thousand years and the outflow rate of active episodes does not significantly change for different stages of the formation process of very low-mass objects. This may provide us with important implications that clarify the formation process of brown dwarfs.

  15. Absorbing Outflows in AGN

    Science.gov (United States)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  16. Astrophysical Jets and Outflows

    CERN Document Server

    De Gouveia dal Pino, E M

    2004-01-01

    Highly collimated supersonic jets and less collimated outflows are observed to emerge from a wide variety of astrophysical objects. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), and in the nuclei of active galaxies (AGNs). Despite their different physical scales (in size, velocity, and amount of energy transported), they have strong morphological similarities. What physics do they share? These systems either hydrodynamic or magnetohydrodynamic (MHD) in nature and are, as such, governed by non-linear equations. While theoretical models helped us to understand the basic physics of these objects, numerical simulations have been allowing us to go beyond the one-dimensional, steady-state approach extracting vital information. In this lecture, the formation, structure, and evolution of the jets are reviewed with the help of observational information, MHD and purely hydrodynamical modeling, and numerical si...

  17. Heating of the Intracluster Medium by Quasar Outflows

    Indian Academy of Sciences (India)

    Suparna Roychowdhury; Biman B. Nath

    2002-03-01

    We study the possibility of quasar outflows in clusters and groups of galaxies heating the intracluster gas in order to explain the recent observation of excess entropy in this gas. We show that radio galaxies alone cannot provide the energy required to explain the observations but the inclusion of Broad Absorption Line (BAL) outflows can do so, and that in this scenario most of the heating takes place at ∼ 1–4, the ``preheating” epoch being at a lower redshift for lower mass clusters.

  18. Do galaxies that leak ionizing photons have extreme outflows?

    Science.gov (United States)

    Chisholm, J.; Orlitová, I.; Schaerer, D.; Verhamme, A.; Worseck, G.; Izotov, Y. I.; Thuan, T. X.; Guseva, N. G.

    2017-09-01

    Context. To reionize the early universe, high-energy photons must escape the galaxies that produce them. How these photons escape is debated because too many ionizing photons are absorbed even at small H i column densities. It has been suggested that stellar feedback drives galactic outflows out of star-forming regions, creating low density channels through which ionizing photons escape into the inter-galactic medium. Aims: We compare the galactic outflow properties of confirmed Lyman continuum (LyC) leaking galaxies to a control sample of nearby star-forming galaxies to explore whether the outflows from leakers are extreme as compared to the control sample. Methods: We use data from the Cosmic Origins Spectrograph on the Hubble Space Telescope to measure the equivalent widths and velocities of Si ii and Si iii absorption lines, tracing neutral and ionized galactic outflows. We explore whether the leakers have similar outflow properties to the control sample, and whether the outflows from the leakers follow similar scaling relations with host galaxy properties as the control sample. We rederive the escape fraction of ionizing photons for each leaker, and study whether the outflow properties influence the LyC escape fractions. Results: We find that the Si ii and Si iii equivalent widths of the LyC leakers reside on the low-end of the trend established by the control sample. The leakers' velocities are not statistically different than the control sample, but their absorption line profiles have a different asymmetry: their central velocities are closer to their maximum velocities. This possibly indicates a more rapidly accelerated outflow due to the compact size of the leakers. The outflow kinematics and equivalent widths are consistent with the scaling relations between outflow properties and host galaxy properties - most notably metallicity - defined by the control sample. Additionally, we use the Lyα profiles to show that the Si ii equivalent width scales with the

  19. SiO line emission from C-type shock waves: interstellar jets and outflows

    Science.gov (United States)

    Gusdorf, A.; Cabrit, S.; Flower, D. R.; Pineau Des Forêts, G.

    2008-05-01

    We study the production of SiO in the gas phase of molecular outflows, through the sputtering of Si-bearing material in refractory grain cores, which are taken to be olivine. We calculate also the rotational line spectrum of the SiO. The sputtering is driven by neutral particle impact on charged grains, in steady-state C-type shock waves, at the speed of ambipolar diffusion. The emission of the SiO molecule is calculated by means of an LVG code. A grid of models, with shock speeds in the range 20 Schilke et al. 1997). Improvements in the treatment of the coupling between the charged grains and the neutral fluid lead to narrower shock waves and lower fractions of Si (⪉10%) being released into the gas phase. Erosion of grain cores is significant (⪆1%) only for C-type shock speeds vs > 25 km s-1, given the adopted properties of olivine. More realistic assumptions concerning the initial fractional abundance of O2 lead to SiO formation being delayed, so that it occurs in the cool, dense postshock flow. Good agreement is obtained with recent observations of SiO line intensities in the L1157 and L1448 molecular outflows. The inferred temperature, opacity, and SiO column density in the emission region differ significantly from those estimated by means of LVG “slab” models. The fractional abundance of SiO is deduced and found to be in the range 4 × 10-8 ⪉ n(SiO)/nH ⪉ 3 × 10-7. Observed line profiles are wider than predicted and imply multiple, unresolved shock regions within the beam.

  20. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  1. Limited Neutrality

    DEFF Research Database (Denmark)

    Nielsen, Morten Ebbe Juul

    2006-01-01

    Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."......Article Concerning the prospect of a kind of limited neutrality in place of the standard liberal egalitarian "neutrality of justification."...

  2. Radiation pressure confinement - IV. Application to broad absorption line outflows

    CERN Document Server

    Baskin, Alexei; Stern, Jonathan

    2014-01-01

    A fraction of quasars present broad absorption lines, produced by outflowing gas with typical velocities of 3000 - 10,000 km/s. If the outflowing gas fills a significant fraction of the volume where it resides, then it will be highly ionized by the quasar due to its low density, and will not produce the observed UV absorption. The suggestion that the outflow is shielded from the ionizing radiation was excluded by recent observations. The remaining solution is a dense outflow with a filling factor $f<10^{-3}$. What produces such a small $f$? Here we point out that radiation pressure confinement (RPC) inevitably leads to gas compression and the formation of dense thin gas sheets/filaments, with a large gradient in density and ionization along the line of sight. The total column of ionized dustless gas is a few times $10^{22}$ cm$^{-2}$, consistent with the observed X-ray absorption and detectable P V absorption. The predicted maximal columns of various ions show a small dependence on the system parameters, a...

  3. Ionization driven molecular outflow in K3-50A

    CERN Document Server

    Klaassen, P D; Peters, T; Longmore, S N; Maercker, M

    2013-01-01

    Whether high mass stars continue to accrete material beyond the formation of an HII region is still an open question. Ionized infall and outflow have been seen in some sources, but their ties to the surrounding molecular gas are not well constrained. We aim to quantify the ionized and molecular gas dynamics in a high mass star forming region (K3-50A) and their interaction. We present CARMA observations of the 3mm continuum, H41\\alpha, and HCO+ emission, and VLA continuum observations at 23 GHz and 14.7 GHz to quantify the gas and its dynamics in K3-50A. We find large scale dynamics consistent with previous observations. On small scales, we find evidence for interaction between the ionized and molecular gas which suggests the ionized outflow is entraining the molecular one. This is the first time such an outflow entrained by photo ionized gas has been observed. Accretion may be ongoing in K3-50A because an ionized bipolar outflow is still being powered, which is in turn entraining part of the surrounding molec...

  4. FIRE simulations: galactic outflows and their consequences

    Science.gov (United States)

    Keres, Dusan; FIRE Team

    2016-06-01

    We study gaseous outflows and their consequences in high-resolution galaxy formation simulations with explicit stellar feedback from the Feedback in Realistic Environments project. Collective, galaxy scale, effect of stellar feedback results in episodic ejections of large amount of gas and heavy elements into the circum-galactic medium. Gas ejection episodes follow strong bursts of star formation. Properties of galactic star formation and ejection episodes depend on galaxy mass and redshift and, together with gas infall and recycling, shape the evolution of the circum-galactic medium and galaxies. As a consequence, our simulated galaxies have masses, star formation histories and heavy element content in good agreement with the observed population of galaxies.

  5. Simulating Supersonic Turbulence in Galaxy Outflows

    CERN Document Server

    Scannapieco, Evan

    2010-01-01

    We present three-dimensional, adaptive mesh simulations of dwarf galaxy out- flows driven by supersonic turbulence. Here we develop a subgrid model to track not only the thermal and bulk velocities of the gas, but also its turbulent velocities and length scales. This allows us to deposit energy from supernovae directly into supersonic turbulence, which acts on scales much larger than a particle mean free path, but much smaller than resolved large-scale flows. Unlike previous approaches, we are able to simulate a starbursting galaxy modeled after NGC 1569, with realistic radiative cooling throughout the simulation. Pockets of hot, diffuse gas around individual OB associations sweep up thick shells of material that persist for long times due to the cooling instability. The overlapping of high-pressure, rarefied regions leads to a collective central outflow that escapes the galaxy by eating away at the exterior gas through turbulent mixing, rather than gathering it into a thin, unstable shell. Supersonic, turbul...

  6. Quasar feedback revealed by giant molecular outflows

    CERN Document Server

    Feruglio, Chiara; Piconcelli, Enrico; Menci, Nicola; Aussel, Herve'; Lamastra, Alessandra; Fiore, Fabrizio

    2010-01-01

    In the standard scenario for galaxy evolution the transformation of young star-forming galaxies into red bulge-dominated spheroids, where star formation has been quenched, is often explained by invoking a strong negative feedback generated by accretion onto a central super-massive black hole. The depletion of gas resulting from quasar-driven outflows should eventually stop star-formation across the host galaxy and lead to the black hole "suicide" for starvation. Direct observational evidence for a major quasar feedback onto the host galaxy is still missing, since outflows previously observed in quasars are associated with the ionized component of the gas, which only accounts for a minor fraction of the total gas content, and typically occur in the central regions. We used the IRAM PdBI to observe the CO(1-0) transition in Mrk 231, the closest quasar known. We detect broad wings of the CO line, with velocities up to 750 km/s and spatially resolved on the kpc scale. Such broad CO wings trace a giant molecular o...

  7. Starburst Galaxies: Outflows of Metals and Energy into the IGM

    CERN Document Server

    Strickland, David K; Ptak, Andrew; Schlegel, Eric; Tremonti, Christy; Tsuru, Takeshi; Tuellmann, Ralph; Zezas, Andreas

    2009-01-01

    What is the contribution of mass, metals and energy from starburst galaxies to the Intergalactic Medium? Starburst galaxies drive galactic-scale outflows or "superwinds" that may be responsible for removing metals from galaxies and polluting the Intergalactic Medium (IGM). In the last decade tremendous progress was made in mapping cool entrained gas in superwinds through UV/optical imaging and absorption line spectroscopy. These studies demonstrated that superwinds are ubiquitous in galaxies forming stars at high surface densities and that the most powerful starbursts can drive outflows near escape velocity. Theoretical models of galaxy evolution have begun to incorporate superwinds, using various ad-hoc prescriptions based on our knowledge of the cool gas. However, these efforts are fundamentally impeded by our lack of information about the hot phase of these outflows. The hot X-ray emitting phase of a superwind contains the majority of its energy and newly-synthesized metals, and given its high specific ene...

  8. Simulations of Metal Enrichment in Galaxy Clusters by AGN Outflows

    CERN Document Server

    Moll, R; Domainko, W; Kapferer, W; Mair, M; Van Kampen, E; Kronberger, T; Kimeswenger, S; Ruffert, M

    2006-01-01

    We assess the importance of AGN outflows with respect to the metal enrichment of the intracluster medium (ICM) in galaxy clusters. We use combined N-body and hydrodynamic simulations, along with a semi-numerical galaxy formation and evolution model. Using assumptions based on observations, we attribute outflows of metal-rich gas initiated by AGN activity to a certain fraction of our model galaxies. The gas is added to the model ICM, where the evolution of the metallicity distribution is calculated by the hydrodynamic simulations. For the parameters describing the AGN content of clusters and their outflow properties, we use the observationally most favorable values. We find that AGNs have the potential to contribute significantly to the metal content of the ICM or even explain the complete abundance, which is typically ~0.5 Z_sun in core regions. Furthermore, the metals end up being inhomogeneously distributed, in accordance with observations.

  9. Astrophysical jets and outflows

    Science.gov (United States)

    de Gouveia Dal Pino, Elisabete M.

    Highly collimated supersonic jets and less collimated outflows are observed to emerge from a wide variety of astrophysical objects. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), and in the nuclei of active galaxies (AGNs). Despite their different physical scales (in size, velocity, and amount of energy transported), they have strong morphological similarities. What physics do they share? These systems are either hydrodynamic or magnetohydrodynamic (MHD) in nature and are, as such, governed by non-linear equations. While theoretical models helped us to understand the basic physics of these objects, numerical simulations have been allowing us to go beyond the one-dimensional, steady-state approach extracting vital information. In this lecture, the formation, structure, and evolution of the jets are reviewed with the help of observational information, MHD and purely hydrodynamical modeling, and numerical simulations. Possible applications of the models particularly to YSOs and AGN jets are addressed.

  10. GBT Detection of Polarization-dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

    CERN Document Server

    Teng, Stacy H; Baker, Andrew J

    2013-01-01

    We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Robert C. Byrd Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L$_{8-1000 \\mu m} > 10^{12}$ L$_\\odot$) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km s$^{-1}$ in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the...

  11. Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: III. The Total Neutral Gas Disk

    CERN Document Server

    Nakanishi, Hiroyuki

    2015-01-01

    We present newly obtained three-dimensional gaseous maps of the Milky Way Galaxy; HI, H$_2$ and total-gas (HI plus H$_2$) maps, which were derived from the HI and $^{12}$CO($J=1$--0) survey data and rotation curves based on the kinematic distance. The HI and H$_2$ face-on maps show that the HI disk is extended to the radius of 15--20 kpc and its outskirt is asymmetric to the Galactic center, while most of the H$_2$ gas is distributed inside the solar circle. The total gas mass within radius 30 kpc amounts to $8.0\\times 10^9$ M$_\\odot$, 89\\% and 11\\% of which are HI and H$_2$, {respectively}. The vertical slices show that the outer HI disk is strongly warped and the inner HI and H$_2$ disks are corrugated. The total gas map is advantageous to trace spiral structure from the inner to outer disk. Spiral structures such as the Norma-Cygnus, the Perseus, the Sagittarius-Carina, the Scutum-Crux, and the Orion arms are more clearly traced in the total gas map than ever. All the spiral arms are well explained with lo...

  12. SiO line emission from C-type shock waves : interstellar jets and outflows

    CERN Document Server

    Gusdorf, A; Flower, D R; Forets, G Pineau des

    2008-01-01

    We study the production of SiO in the gas phase of molecular outflows, through the sputtering of Si--bearing material in refractory grain cores, which are taken to be olivine; we calculate also the rotational line spectrum of the SiO. The sputtering is driven by neutral particle impact on charged grains, in steady--state C-type shock waves, at the speed of ambipolar diffusion. The emission of the SiO molecule is calculated by means of an LVG code. A grid of models has been generated. We compare our results with those of an earlier study (Schilke et al. 1997). Improvements in the treatment of the coupling between the charged grains and the neutral fluid lead to narrower shock waves and lower fractions of Si being released into the gas phase. More realistic assumptions concerning the initial fractional abundance of O2 lead to SiO formation being delayed, so that it occurs in the cool, dense postshock flow. Good agreement is obtained with recent observations of SiO line intensities in the L1157 and L1448 molecul...

  13. Energy exchanges in reconnection outflows

    Science.gov (United States)

    Lapenta, Giovanni; Goldman, Martin V.; Newman, David L.; Markidis, Stefano

    2017-01-01

    Reconnection outflows are highly energetic directed flows that interact with the ambient plasma or with flows from other reconnection regions. Under these conditions the flow becomes highly unstable and chaotic, as any flow jets interacting with a medium. We report here massively parallel simulations of the two cases of interaction between outflow jets and between a single outflow with an ambient plasma. We find in both case the development of a chaotic magnetic field, subject to secondary reconnection events that further complicate the topology of the field lines. The focus of the present analysis is on the energy balance. We compute each energy channel (electromagnetic, bulk, thermal, for each species) and find where the most energy is exchanged and in what form. The main finding is that the largest energy exchange is not at the reconnection site proper but in the regions where the outflowing jets are destabilized.

  14. Overconsumption, outflows and the quenching of satellite galaxies

    Science.gov (United States)

    McGee, Sean L.; Bower, Richard G.; Balogh, Michael L.

    2014-07-01

    The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events - either direct stripping of the disc (ram pressure stripping) or the extended gas halo (strangulation) - or from internally driven star formation outflows via overconsumption. These time-scales show significant deviations from the evolution expected for gas stripping mechanisms and suggest that either ram pressure stripping is much more efficient at high redshift, or that secular outflows quench satellites before orbit-based stripping occurs. Given the strong redshift evolution of star formation rates, at high redshift even moderate outflow rates will lead to extremely short delay times with the expectation that high-redshift (z > 1.5) satellites will be quenched almost immediately following the cessation of cosmological inflow. Observations of high-redshift satellites give an indirect but sensitive measure of the outflow rate, with current measurements suggesting that outflows are no larger than 2.5 times the star formation rate for galaxies with a stellar mass of 1010.5 M⊙.

  15. Protostellar Outflows and Radiative Feedback from Massive Stars. II. Feedback, Star-formation Efficiency, and Outflow Broadening

    Science.gov (United States)

    Kuiper, Rolf; Turner, Neal J.; Yorke, Harold W.

    2016-11-01

    We perform two-dimensional axially symmetric radiation hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, and to determine the ratio of ejection to accretion rates and the strength of the wide-angle disk wind component. The star-formation efficiency, i.e., the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects. First, the protostar grows slower with a lower luminosity at any given time, lowering radiative feedback. Second, bipolar cavities cleared by the outflow become larger, further diminishing radiative feedback on disk and core scales. Third, the higher momentum outflow sweeps up more material from the collapsing envelope, decreasing the protostar's potential mass reservoir via entrainment. The star-formation efficiency varies with the ratio of ejection to accretion rates from 50% in the case of very weak outflows to as low as 20% for very strong outflows. At latitudes between the low-density bipolar cavity and the high-density accretion disk, wide-angle disk winds remove some of the gas, which otherwise would be part of the accretion flow onto the disk; varying the strength of these wide-angle disk winds, however, alters the final star-formation efficiency by only ±6%. For all cases, the opening angle of the bipolar outflow cavity remains below 20° during early protostellar accretion phases, increasing rapidly up to 65° at the onset of radiation pressure feedback.

  16. The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star Forming Galaxies from z~1 to z~3

    CERN Document Server

    Rafelski, Marc; Fumagalli, Michele; Neeleman, Marcel; Teplitz, Harry I; Grogin, Norman; Koekemoer, Anton M; Scarlata, Claudia

    2016-01-01

    Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Ly-alpha Systems (DLAs) at z~3 is more than 10 times lower than predicted by the Kennicutt-Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galaxy properties, we measure the SFR efficiency of atomic gas at z~1, z~2, and z~3 around star-forming galaxies. We use new robust photometric redshifts in the Hubble Ultra Deep Field to create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies' outskirts. We find that the SFR efficiency of HI gas at z>1 is ~1-3% of that predicted by the KS relation. Contrary to simulations and models that predict a reduced SFR efficiency with decreasing metallicity and thus with increasing redshift, we find no significant evolution in the SFR efficiency with redshift...

  17. Shocks in nova outflows. I. Thermal emission

    CERN Document Server

    Metzger, Brian D; Vurm, Indrek; Beloborodov, Andrei M; Chomiuk, Laura; Sokoloski, J L; Nelson, Thomas

    2014-01-01

    Evidence for shocks in nova outflows include (1) multiple velocity components in the optical spectra; (2) keV X-ray emission weeks to months after the outburst; (3) early radio flare on timescales of months, in excess of that predicted from the freely expanding photo-ionized gas; and (4) ~ GeV gamma-rays. We present a 1D model for the shock interaction between the fast nova outflow and a dense external shell (DES) and its associated thermal X-ray, optical, and radio emission. The forward shock is radiative initially when the density of shocked gas is highest, at which times radio emission originates from the dense cooling layer immediately downstream of the shock. The radio light curve is characterized by sharper rises to maximum and later peak times at progressively lower frequencies, with a peak brightness temperature that is approximately independent of frequency. We apply our model to the recent gamma-ray classical nova V1324 Sco, obtaining an adequate fit to the early radio maximum for reasonable assumpt...

  18. Ionized Outflows from Compact Steep Spectrum Sources

    CERN Document Server

    Shih, Hsin-Yi; Kewley, Lisa

    2013-01-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10$^3$ to 10$^5$ years old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using GMOS on Gemini North. We fit the [\\ion{O}{3}] $\\lambda 5007$ line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of diffe...

  19. Multidimensional chemical modelling, II. Irradiated outflow walls

    CERN Document Server

    Bruderer, Simon; Doty, Steven D; van Dishoeck, Ewine F; Bourke, Tyler L

    2009-01-01

    Observations of the high-mass star forming region AFGL 2591 reveal a large abundance of CO+, a molecule known to be enhanced by far UV (FUV) and X-ray irradiation. In chemical models assuming a spherically symmetric envelope, the volume of gas irradiated by protostellar FUV radiation is very small due to the high extinction by dust. The abundance of CO+ is thus underpredicted by orders of magnitude. In a more realistic model, FUV photons can escape through an outflow region and irradiate gas at the border to the envelope. Thus, we introduce the first 2D axi-symmetric chemical model of the envelope of a high-mass star forming region to explain the CO+ observations as a prototypical FUV tracer. The model assumes an axi-symmetric power-law density structure with a cavity due to the outflow. The local FUV flux is calculated by a Monte Carlo radiative transfer code taking scattering on dust into account. A grid of precalculated chemical abundances, introduced in the first part of this series of papers, is used to ...

  20. How stellar feedback simultaneously regulates star formation and drives outflows

    Science.gov (United States)

    Hayward, Christopher C.; Hopkins, Philip F.

    2017-02-01

    We present an analytic model for how momentum deposition from stellar feedback simultaneously regulates star formation and drives outflows in a turbulent interstellar medium (ISM). Because the ISM is turbulent, a given patch of ISM exhibits sub-patches with a range of surface densities. The high-density patches are `pushed' by feedback, thereby driving turbulence and self-regulating local star formation. Sufficiently low-density patches, however, are accelerated to above the escape velocity before the region can self-adjust and are thus vented as outflows. When the gas fraction is ≳ 0.3, the ratio of the turbulent velocity dispersion to the circular velocity is sufficiently high that at any given time, of the order of half of the ISM has surface density less than the critical value and thus can be blown out on a dynamical time. The resulting outflows have a mass-loading factor (η ≡ dot{M}_{out}/M_{star}) that is inversely proportional to the gas fraction times the circular velocity. At low gas fractions, the star formation rate needed for local self-regulation, and corresponding turbulent Mach number, declines rapidly; the ISM is `smoother', and it is actually more difficult to drive winds with large mass-loading factors. Crucially, our model predicts that stellar-feedback-driven outflows should be suppressed at z ≲ 1 in M⋆ ≳ 1010 M⊙ galaxies. This mechanism allows massive galaxies to exhibit violent outflows at high redshifts and then `shut down' those outflows at late times, thereby enabling the formation of a smooth, extended thin stellar disc. We provide simple fitting functions for η that should be useful for sub-resolution and semi-analytic models.

  1. Improvement of activated carbons as oxygen reduction catalysts in neutral solutions by ammonia gas treatment and their performance in microbial fuel cells

    KAUST Repository

    Watson, Valerie J.

    2013-11-01

    Commercially available activated carbon (AC) powders from different precursor materials (peat, coconut shell, coal, and hardwood) were treated with ammonia gas at 700 C to improve their performance as oxygen reduction catalysts in neutral pH solutions used in microbial fuel cells (MFCs). The ammonia treated ACs exhibited better catalytic performance in rotating ring-disk electrode tests than their untreated precursors, with the bituminous based AC most improved, with an onset potential of Eonset = 0.12 V (untreated, Eonset = 0.08 V) and n = 3.9 electrons transferred in oxygen reduction (untreated, n = 3.6), and the hardwood based AC (treated, E onset = 0.03 V, n = 3.3; untreated, Eonset = -0.04 V, n = 3.0). Ammonia treatment decreased oxygen content by 29-58%, increased nitrogen content to 1.8 atomic %, and increased the basicity of the bituminous, peat, and hardwood ACs. The treated coal based AC cathodes had higher maximum power densities in MFCs (2450 ± 40 mW m-2) than the other AC cathodes or a Pt/C cathode (2100 ± 1 mW m-2). These results show that reduced oxygen abundance and increased nitrogen functionalities on the AC surface can increase catalytic performance for oxygen reduction in neutral media. © 2013 Elsevier B.V. All rights reserved.

  2. Multi-wavelength, Multi-scale Observations of Outflows in Star-Forming Regions

    Science.gov (United States)

    Plunkett, Adele Laurie Dennis

    During the early stages of star formation, an embedded protostar accretes mass and simultaneously expels mass and angular momentum in the form of a bipolar outflow. In the common case of clustered star formation, outflows likely impact their surrounding environment and influence subsequent star formation. Numerical simulations have shown that outflows can sustain turbulence and maintain a cluster in quasi-equilibrium; alternatively, it was proposed that outflows may trigger rather than regulate or inhibit star formation. Observations of outflows and their impact on clusters are challenging because they must probe spatial scales over several orders of magnitude --- from the size of a core (a few hundred AU, or N ~ 10-3 pc) to a cluster (a few pc) --- and previous works generally focused on one scale or the other. This thesis incorporates high-resolution, high-sensitivity interferometry observations (with millimeter/sub-millimeter wavelengths) complemented by observations obtained using single dish telescopes in order to assess molecular outflow properties and their cumulative impact in two young protostellar clusters: Serpens South and NGC 1333. Based on these case studies, I develop an evolutionary scenario for clustered star formation spanning the ages of the two clusters, about 0.1 - 1 Myr. Within this scenario, outflows in both Serpens South and NGC 1333 provide sufficient energy to sustain turbulence early in the protocluster formation process. In neither cluster do outflows provide enough energy to counter the gravitational potential energy and disrupt the entire cluster. However, most of the mass in outflows in both clusters have velocities greater than the escape velocity, and therefore the relative importance of outflow-driven turbulence compared with gravitational potential likely changes with time as ambient gas escapes. We estimate that enough gas mass will escape via outflows in Serpens South so that it will come to resemble NGC 1333 in terms of its

  3. Neutral hydrogen gas, past and future star-formation in galaxies in and around the 'Sausage' merging galaxy cluster

    CERN Document Server

    Stroe, Andra; Rottgering, Huub J A; Sobral, David; van Weeren, Reinout; Dawson, William

    2015-01-01

    CIZA J2242.8+5301 ($z = 0.188$, nicknamed 'Sausage') is an extremely massive ($M_{200}\\sim 2.0 \\times 10^{15}M_\\odot$ ), merging cluster with shock waves towards its outskirts, which was found to host numerous emission-line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope HI observations of the 'Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission-line galaxies in the 'Sausage' cluster have, on average, as much HI gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large HI reservoirs are expected to be consumed within $\\sim0.75-1.0$ Gyr by the vigorous SF and AGN activity and/or driven out by t...

  4. Spatial Variations of Turbulent Properties of Neutral Hydrogen Gas in the Small Magellanic Cloud Using Structure-function Analysis

    Science.gov (United States)

    Nestingen-Palm, David; Stanimirović, Snežana; González-Casanova, Diego F.; Babler, Brian; Jameson, Katherine; Bolatto, Alberto

    2017-08-01

    We investigate spatial variations of turbulent properties in the Small Magellanic Cloud (SMC) by using neutral hydrogen (H i) observations. With the goal of testing the importance of stellar feedback on H i turbulence, we define central and outer SMC regions based on the star formation rate (SFR) surface density, as well as the H i integrated intensity. We use the structure function and the velocity channel analysis to calculate the power-law index (γ) for both underlying density and velocity fields in these regions. In all cases, our results show essentially no difference in γ between the central and outer regions. This suggests that H i turbulent properties are surprisingly homogeneous across the SMC when probed at a resolution of 30 pc. Contrary to recent suggestions from numerical simulations, we do not find a significant change in γ due to stellar feedback as traced by the SFR surface density. This could be due to the stellar feedback being widespread over the whole of the SMC, but more likely due to a large-scale gravitational driving of turbulence. We show that the lack of difference between central and outer SMC regions cannot be explained by the high optical depth H I.

  5. Effect of boundary conditions on the neutral gas temperatures and densities in the ITER divertor and pump duct

    Science.gov (United States)

    Ruzic, D. N.; Juliano, D. R.

    1992-12-01

    The DEGAS neutral atom transport code was used to simulate helium pumping and D/T throughput in ITER. The sensitivity of the simulation to two different reflection models, four transmission probabilities from the exit of the simulation to the pump (0.0625, 0.125, 0.1875 and 0.250), and a 2-D model versus a 3-D model were analyzed. The variation in reflection model changes the densities in the duct and the recycling of D/T by a factor of 1.6. The variation in the transmission probabilities affects these same quantities by a factor of 2.5. The dimensionality of the simulation affects the density profile in the duct. A transmission probability from the exit of the DEGAS simulation to the pump of 0.110 to 0.125 was calculated from the ITER reference drawings. Using this quantity and the DEGAS results, an exhaust rate of 112 to 127 moles/h is predicted, implying that the reference pumping systems may be larger than necessary by a factor of 2.

  6. A simulation study of interactions of space-shuttle generated electron beams with ambient plasma and neutral gas

    Science.gov (United States)

    Winglee, Robert M.

    1991-01-01

    The objective was to conduct large scale simulations of electron beams injected into space. The study of the active injection of electron beams from spacecraft is important, as it provides valuable insight into the plasma beam interactions and the development of current systems in the ionosphere. However, the beam injection itself is not simple, being constrained by the ability of the spacecraft to draw current from the ambient plasma. The generation of these return currents is dependent on several factors, including the density of the ambient plasma relative to the beam density, the presence of neutrals around the spacecraft, the configuration of the spacecraft, and the motion of the spacecraft through the plasma. Two dimensional (three velocity) particle simulations with collisional processes included are used to show how these different and often coupled processes can be used to enhance beam propagation from the spacecraft. To understand the radial expansion mechanism of an electron beam injected from a highly charged spacecraft, two dimensional particle-in-cell simulations were conducted for a high density electron beam injected parallel to magnetic fields from an isolated equipotential conductor into a cold background plasma. The simulations indicate that charge build-up at the beam stagnation point causes the beam to expand radially to the beam electron gyroradius.

  7. Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy

    CERN Document Server

    Geach, J E; Diamond-Stanic, A M; Krips, M; Rudnick, G H; Tremonti, C A; Sell, P H; Coil, A L; Moustakas, J

    2014-01-01

    Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and are restricted to sub-kiloparsec scales. It is also apparent that input from active galactic nuclei is in at least some cases dynamically important, so pure stellar feedback has been considered incapable of aggressively terminating star formation on galactic scales. Extraplanar molecular gas has been detected in the archetype starburst galaxy M82, but so far there has been no evidence that starbursts can propel significant quantities of cold molecular gas to the same galactocentric radius (~10 kpc) as the warmer gas traced by metal absorbers. Here we report observations of molecular gas in a compact (effective radius 100 pc) massive starburst galaxy at z...

  8. Fueling AGN II: Spatially Resolved Molecular Inflows and Outflows

    CERN Document Server

    Davies, R I; Hicks, E K S; Emsellem, E; Erwin, P; Burtscher, L; Dumas, G; Lin, M; Malkan, M A; Mueller-Sanchez, F; de Xivry, G Orban; Rosario, D J; Schnorr-Mueller, A; Tran, A

    2014-01-01

    We analyse the 2-dimensional distribution and kinematics of the stars as well as molecular and ionised gas in the central few hundred parsecs of 5 active and 5 matched inactive galaxies. The equivalent widths of the Br-gamma line indicate there is no on-going star formation in their nuclei, although recent (terminated) starbursts are possible in the active galaxies. The stellar velocity fields show no signs of non-circular motions, while the 1-0S(1) H_2 kinematics exhibit significant deviations from simple circular rotation. In the active galaxies the H_2 kinematics reveal inflow and outflow superimposed on disk rotation. Steady-state circumnuclear inflow is seen in three AGN, and hydrodynamical models indicate it can be driven by a large scale bar. In three of the five AGN, molecular outflows are spatially resolved. The outflows are oriented such that they intersect, or have an edge close to, the disk - which may be the source of molecular gas in the outflow. The relatively low speeds imply the gas will fall...

  9. PROTOSTELLAR OUTFLOW HEATING IN A GROWING MASSIVE PROTOCLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ke; Wu Yuefang; Zhang Huawei [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zhang Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Li Huabai, E-mail: kwang@cfa.harvard.edu [Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2012-02-15

    The dense molecular clump P1 in the infrared dark cloud complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here, we present the Expanded Very Large Array spectral line observations toward P1 in the NH{sub 3} (J,K) = (1,1), (2,2), (3,3) lines, as well as H{sub 2}O and class I CH{sub 3}OH masers. Multiple NH{sub 3} transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH{sub 3} (3,3) emission features are also found coincident with the outflows. A weak NH{sub 3} (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may not be effective in suppressing fragmentation during the formation of massive cores.

  10. Protostellar Outflow Heating in a Growing Massive Protocluster

    CERN Document Server

    Wang, Ke; Wu, Yuefang; Li, Hua-bai; Zhang, Huawei

    2011-01-01

    The dense molecular clump P1 in the infrared dark cloud (IRDC) complex G28.34+0.06 harbors a massive protostellar cluster at its extreme youth. Our previous Submillimeter Array (SMA) observations revealed several jet-like CO outflows emanating from the protostars, indicative of intense accretion and potential interaction with ambient natal materials. Here we present the Expanded Very Large Array (EVLA) spectral line observations toward P1 in the NH3 (J,K) = (1,1), (2,2), (3,3) lines, as well as H2O and class I CH3OH masers. Multiple NH3 transitions reveal the heated gas widely spread in the 1 pc clump. The temperature distribution is highly structured; the heated gas is offset from the protostars, and morphologically matches the outflows very well. Hot spots of spatially compact, spectrally broad NH3 (3,3) emission are also found coincident with the outflows. A weak NH3 (3,3) maser is discovered at the interface between an outflow jet and the ambient gas. These findings suggest that protostellar heating may n...

  11. OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan [Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhang, Kai [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang, Shaohua, E-mail: whywang@mail.ustc.edu.cn [Polar Research Institute of China, Jinqiao Road 451, Shanghai 200136 (China)

    2013-10-10

    Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus.

  12. Knowledge Outflows from Foreign Subsidiaries

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf

    This paper analyzes the MNC subsidiaries’ trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we find......-mediated local knowledge outflows, as well as to the broad IB literature on the relationship between subsidiaries and their host regions. The implications for managers and policy-makers are also discussed....... that subsidiaries that extensively draw on external knowledge sources are also more likely to generate knowledge outflows to local firms. We argue that this may be explained by the subsidiaries’ willingness to build the trust that facilitates the establishment of reciprocal knowledge linkages. However, when...

  13. Line-driven radiative outflows in luminous quasars

    CERN Document Server

    Bowler, Rebecca A A; Allen, James T; Ferland, Gary J

    2014-01-01

    An analysis of ~19500 narrow (<200 km/s) CIV 1548.2,1550.8 absorbers in ~34000 Sloan Digital Sky Survey quasar spectra is presented. The statistics of the number of absorbers as a function of outflow-velocity shows that in approximately two-thirds of outflows, with multiple CIV absorbers present, absorbers are line-locked at the 500 km/s velocity separation of the CIV absorber doublet; appearing as 'triplets' in the quasar spectra. Line-locking is an observational signature of radiative line driving in outflowing material, where the successive shielding of 'clouds' of material in the outflow locks the clouds together in outflow velocity. Line-locked absorbers are seen in both broad absorption line quasars (BALs) and non-BAL quasars with comparable frequencies and with velocities out to at least 20000 km/s. There are no detectable differences in the absorber properties and the dust content of single CIV doublets and line-locked CIV doublets. The gas associated with both single and line-locked CIV absorption...

  14. Molecular Outflows: Explosive versus Protostellar

    Science.gov (United States)

    Zapata, Luis A.; Schmid-Burgk, Johannes; Rodríguez, Luis F.; Palau, Aina; Loinard, Laurent

    2017-02-01

    With the recent recognition of a second, distinctive class of molecular outflows, namely the explosive ones not directly connected to the accretion–ejection process in star formation, a juxtaposition of the morphological and kinematic properties of both classes is warranted. By applying the same method used in Zapata et al., and using 12CO(J = 2-1) archival data from the Submillimeter Array, we contrast two well-known explosive objects, Orion KL and DR21, to HH 211 and DG Tau B, two flows representative of classical low-mass protostellar outflows. At the moment, there are only two well-established cases of explosive outflows, but with the full availability of ALMA we expect that more examples will be found in the near future. The main results are the largely different spatial distributions of the explosive flows, consisting of numerous narrow straight filament-like ejections with different orientations and in almost an isotropic configuration, the redshifted with respect to the blueshifted components of the flows (maximally separated in protostellar, largely overlapping in explosive outflows), the very-well-defined Hubble flow-like increase of velocity with distance from the origin in the explosive filaments versus the mostly non-organized CO velocity field in protostellar objects, and huge inequalities in mass, momentum, and energy of the two classes, at least for the case of low-mass flows. Finally, all the molecular filaments in the explosive outflows point back to approximately a central position (i.e., the place where its “exciting source” was located), contrary to the bulk of the molecular material within the protostellar outflows.

  15. (abstract) A Test of the Theoretical Models of Bipolar Outflows: The Bipolar Outflow in Mon R2

    Science.gov (United States)

    Xie, Taoling; Goldsmith, Paul; Patel, Nimesh

    1993-01-01

    We report some results of a study of the massive bipolar outflow in the central region of the relatively nearby giant molecular cloud Monoceros R2. We make a quantative comparison of our results with the Shu et al. outflow model which incorporates a radially directed wind sweeping up the ambient material into a shell. We find that this simple model naturally explains the shape of this thin shell. Although Shu's model in its simplest form predicts with reasonable parameters too much mass at very small polar angles, as previously pointed out by Masson and Chernin, it provides a reasonable good fit to the mass distribution at larger polar angles. It is possible that this discrepancy is due to inhomogeneities of the ambient molecular gas which is not considered by the model. We also discuss the constraints imposed by these results on recent jet-driven outflow models.

  16. Prediction of neutral noble gas insertion compounds with heavier pnictides: FNgY (Ng = Kr and Xe; Y = As, Sb and Bi).

    Science.gov (United States)

    Ghosh, Ayan; Manna, Debashree; Ghanty, Tapan K

    2016-04-28

    A novel class of interesting insertion compounds obtained through the insertion of a noble gas atom into the heavier pnictides have been explored by various ab initio quantum chemical techniques. Recently, the first neutral noble gas insertion compounds, FXeY (Y = P, N), were theoretically predicted to be stable; the triplet state was found to be the most stable state, with a high triplet-singlet energy gap, by our group. In this study, we investigated another noble gas inserted compound, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi), with a triplet ground state. Density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)) and multi-reference configuration interaction (MRCI) based techniques have been utilized to investigate the structures, stabilities, harmonic vibrational frequencies, charge distributions and topological properties of these compounds. These predicted species, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi) are found to be energetically stable with respect to all the probable 2-body and 3-body dissociation pathways, except for the 2-body channel leading to the global minimum products (FY + Ng). Nevertheless, the finite barrier height corresponding to the saddle points of the compounds connected to their respective global minima products indicates that these compounds are kinetically stable. The structural parameters, energetics, and charge distribution results as well as atoms-in-molecules (AIM) analysis suggest that these predicted molecules can be best represented as F(-)[(3)NgY](+). Thus, all the aforementioned computed results clearly indicate that it may be possible to experimentally prepare the most stable triplet state of FNgY molecules under cryogenic conditions through a matrix isolation technique.

  17. Cosmic ray driven outflows

    CERN Document Server

    Hanasz, Michal; Naab, Thorsten; Gawryszczak, Artur; Kowalik, Kacper; Wóltański, Dominik

    2013-01-01

    We present simulations of the magnetized interstellar medium (ISM) in models of massive star forming (40 Msun / yr) disk galaxies with high gas surface densities (~100 Msun / pc^2) similar to observed star forming high-redshift disks. We assume that type II supernovae deposit 10 per cent of their energy into the ISM as cosmic rays and neglect the additional deposition of thermal energy or momentum. With a typical Galactic diffusion coefficient for CRs (3e28 cm^2 / s) we demonstrate that this process alone can trigger the local formation of a strong low density galactic wind maintaining vertically open field lines. Driven by the additional pressure gradient of the relativistic fluid the wind speed can exceed 1000 km/s, much higher than the escape velocity of the galaxy. The global mass loading, i.e. the ratio of the gas mass leaving the galactic disk in a wind to the star formation rate becomes of order unity once the system has settled into an equilibrium. We conclude that relativistic particles accelerated i...

  18. Impact of Protostellar Outflows on Turbulence and Star Formation Efficiency in Magnetized Dense Cores

    Science.gov (United States)

    Offner, Stella S. R.; Chaban, Jonah

    2017-10-01

    The star-forming efficiency of dense gas is thought to be set within cores by outflow and radiative feedback. We use magnetohydrodynamic simulations to investigate the relation between protostellar outflow evolution, turbulence, and star formation efficiency. We model the collapse and evolution of isolated dense cores for ≳0.5 Myr including the effects of turbulence, radiation transfer, and both radiation and outflow feedback from forming protostars. We show that outflows drive and maintain turbulence in the core environment even with strong initial fields. The star formation efficiency decreases with increasing field strength, and the final efficiencies are 15%–40%. The Stage 0 lifetime, during which the protostellar mass is lower than that of the dense envelope, increases proportionally with the initial magnetic field strength and ranges from ∼ 0.1 {to} 0.4 {Myr}. The average accretion rate is well represented by a tapered turbulent core model, which is a function of the final protostellar mass and is independent of the magnetic field strength. By tagging material launched in the outflow, we demonstrate that the outflow entrains about three times the actual launched gas mass, a ratio that remains roughly constant in time regardless of the initial magnetic field strength. However, turbulent driving increases for stronger fields since momentum is more efficiently imparted to non-outflow material. The protostellar outflow momentum is highest during the first 0.1 Myr and declines thereafter by a factor of ≳ 10 as the accretion rate diminishes.

  19. GBT Detection of Polarization-Dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

    Science.gov (United States)

    Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J.

    2013-01-01

    We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L(sub 8 - 1000 micron) > 10(exp 12) solar L) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km/s in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground HI clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the approx 10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into "mature" radio galaxies.

  20. SiO: Not the perfect outflow tracer: Outflow studies of the massive star formation region IRAS 19410+2336

    CERN Document Server

    Widmann, Felix; Schilke, Peter; Stanke, Thomas

    2016-01-01

    Aims: Previous observations of the young massive star formation region IRAS 19410+2336 have revealed strong outflow activity with several interacting outflows. We aim to get a better understanding of the outflow activity in this region by observing the SiO and H$^{13}$CO$^+$ emission with high angular resolution. SiO is known to trace shocked gas, which is often associated with young energetic outflows. With the H$^{13}$CO$^+$ data, we intend to better understand the distribution of the quiescent gaseous component of the region. Methods: The SiO observations in the J=2-1 v=0 transition and H$^{13}$CO$^+$ J=1-0 observations were performed by the Plateau de Bure Interferometer, combined with IRAM 30 m single-dish observations, in order to get the missing short-spacing information. We complement this new high-resolution observation with earlier CO and H$_2$ data. Results: The SiO observations do not trace the previously in CO and H$_2$ identified outflows well. Although we identify regions of highly increased Si...

  1. Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 region. IV Interaction between the Outflow and the Dense Gas in the Cluster Forming Region of OMC-2 FIR 6

    CERN Document Server

    Shimajiri, Yoshito; Takakuwa, Shigehisa; Saito, Masao; Kawabe, Ryohei

    2009-01-01

    We have conducted millimeter interferometric observations of the Orion Molecular Cloud-2 (OMC-2) FIR 6 region at an angular resolution of $\\sim$ 4$\\arcsec$ - 7$\\arcsec$ with the Nobeyama Millimeter Array (NMA). In the 3.3 mm continuum emission we detected dusty core counterparts of the previously identified FIR sources (FIR 6a, 6b, 6c, and 6d), and moreover, resolved FIR 6a into three dusty cores. The size and mass of these cores are estimated to be 1100-5900 AU and 0.19-5.5 M$_{\\odot}$, respectively. We found that in the $^{12}$CO ($J$=1--0) emission FIR 6b, 6c, and 6d eject the molecular outflow and that the FIR 6c outflow also exhibits at least two collimated jet-like components in the SiO ($J$=2--1) emission. At the tip of one of the SiO components there appears abrupt increase of the SiO line width ($\\sim$ 15 km s$^{-1}$), where the three resolved cores in FIR 6a seem to delineate the tip. These results imply the presence of the interaction and the bowshock front between the FIR 6c molecular outflow and ...

  2. On the Formation of Molecular Clumps in QSO Outflows

    Science.gov (United States)

    Ferrara, A.; Scannapieco, E.

    2016-12-01

    We study the origin of the cold molecular clumps in quasar outflows, recently detected in CO and HCN emission. We first describe the physical properties of such radiation-driven outflows and show that a transition from a momentum- to an energy-driven flow must occur at a radial distance of R≈ 0.25 {kpc}. During this transition, the shell of swept-up material fragments due to Rayleigh-Taylor instabilities, but these clumps contain little mass and are likely to be rapidly ablated by the hot gas in which they are immersed. We then explore an alternative scenario in which clumps form from thermal instabilities at R≳ 1 {kpc}, possibly containing enough dust to catalyze molecule formation. We investigate this process with 3D two-fluid (gas+dust) numerical simulations of a kpc3 patch of the outflow, including atomic and dust cooling, thermal conduction, dust sputtering, and photoionization from the QSO radiation field. In all cases, dust grains are rapidly destroyed in ≈ {10}4 years; and while some cold clumps form at later times, they are present only as transient features, which disappear as cooling becomes more widespread. In fact, we only find a stable two-phase medium with dense clumps if we artificially enhance the QSO radiation field by a factor of 100. This result, together with the complete destruction of dust grains, renders the interpretation of molecular outflows a very challenging problem.

  3. ALMA Observations of the HH 46/47 Molecular Outflow

    CERN Document Server

    Arce, Hector G; Corder, Stuartt; Garay, Guido; Noriega-Crespo, Alberto; Raga, Alejandro C; Cabrit, Sylvie

    2013-01-01

    The morphology, kinematics and entrainment mechanism of the HH 46/47 molecular outflow were studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly different. We argue that these differences are partly due to contrasting ambient densities that result in different wind components having a distinct effect on the entrained gas in each lobe. A 29-point mosaic, covering the two lobes at an angular resolution of about 3", detected outflow emission at much higher velocities than previous observations, resulting in significantly higher estimates of the outflow momentum and kinetic energy than previous studies of this source, using the CO(1-0) line. The morphology and the kinematics of the gas in the blue lobe are consistent with models of outflow entrainment by a wide-angle wind, and a simple model may describe the observed structures in the position-velocity diagram and the integrated intensity map. The red lobe exhibits a more complex structure, and there is evidence tha...

  4. Protostellar Outflows in L1340

    CERN Document Server

    Walawender, Josh; Smutko, Michael; O'Linger-Luscusk, JoAnn; Moriarty-Schieven, Gerald

    2016-01-01

    We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H$_2$ 2.122 $\\mu$m near-IR line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, & L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes in to 12 distinct outflows and identify candidate source stars for each. We examine the properties (A$_{V}$, T$_{bol}$, and L$_{bol}$) of the source protostars and compare that to the properties of the general population of Class 0/I and flat SED protostars and find that there is an indication, albeit at low statistical significance, that the outflow driving protostars are drawn from a population with lower A$_{V}$, higher L$_{bol}$, and lower T$_{bol}$ than the general population of protostars.

  5. Molecular outflows in starburst nuclei

    CERN Document Server

    Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.

  6. Measuring the seeds of thermal ion outflow

    Science.gov (United States)

    Fernandes, Philip A.

    The ionosphere is the primary source for heavy ions which are ubiquitous in the terrestrial magnetosphere. Low-altitude energization in the auroral ionosphere results in bulk heating and transverse acceleration of ions, which begin to upwell and/or be accelerated upward by the mirror force, starting upflow and leading to the outflow process. The details of the processes that seed ion outflow at low altitudes are difficult to measure in situ and thus remain an open question. We examine the observational parameter regime in which ion upflow/outflow initiates. Emphasis is placed on making measurements of the thermal ion kinetic distribution function, allowing for accounting of processes which affect in situ plasma measurements. We consider an electrostatic analyzer (ESA) instrument capable of making the measurements necessary to quantify the roles of various heating mechanisms in initiating ion upflow in the low-altitude auroral ionosphere. We present the difficulties associated with making these measurements and identify instrument design choices that mitigate some of these measurement challenges. Analysis of ESA measurements of the thermal ion distribution function taken on the MICA auroral sounding rocket is presented. Using a Maxwellian model to replicate possible measured spectra, we calculate integrated parameters from the model and compare with equivalent parameters calculated from the in situ data. Through Liouville's theorem and the thin-sheath approximation we couple the measured and forward-modeled parameters such that measurements inside the sheath provide information about the state of the plasma outside the sheath. Throughout the MICA flight, ion upflow is observed and attributed to ambipolar electric fields and/or ion-neutral interactions. Late in the flight we observe quasi-static frictional process driving the ion temperature. Early in the flight we observe ion heating weakly correlated with ELF wave activity; our analysis suggests we must consider

  7. Outflow and metallicity in the broad-line region of low-redshift active galactic nuclei

    CERN Document Server

    Shin, Jaejin; Woo, Jong-Hak

    2016-01-01

    Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on the archival UV spectra obtained with HST and IUE, we investigate outflows in the broad-line region (BLR) in low-redshift AGNs (z < 0.4) through the detailed analysis of the velocity profile of the CIV emission line. We find a dependence of the outflow strength on the Eddington ratio and the BLR metallicity in our low-redshift AGN sample, which is consistent with the earlier results obtained for high-redshift quasars. These results suggest that the BLR outflows, gas accretion onto SMBH, and past star-formation activity in the host galaxies are physically related in low-redshift AGNs as in powerful high-redshift quasars.

  8. The connection between AGN-driven dusty outflows and the surrounding environment

    Science.gov (United States)

    Ishibashi, W.; Fabian, A. C.

    2016-04-01

    Significant reservoirs of cool gas are observed in the circumgalactic medium (CGM) surrounding galaxies. The CGM is also found to contain substantial amounts of metals and dust, which require some transport mechanism. We consider AGN (active galactic nucleus) feedback-driven outflows based on radiation pressure on dust. Dusty gas is ejected when the central luminosity exceeds the effective Eddington luminosity for dust. We obtain that a higher dust-to-gas ratio leads to a lower critical luminosity, implying that the more dusty gas is more easily expelled. Dusty outflows can reach large radii with a range of velocities (depending on the outflowing shell configuration and the ambient density distribution) and may account for the observed CGM gas. In our picture, dust is required in order to drive AGN feedback, and the preferential expulsion of dusty gas in the outflows may naturally explain the presence of dust in the CGM. On the other hand, the most powerful AGN outflow events can potentially drive gas out of the local galaxy group. We further discuss the effects of radiation pressure of the central AGN on satellite galaxies. AGN radiative feedback may therefore have a significant impact on the evolution of the whole surrounding environment.

  9. The connection between AGN-driven dusty outflows and the surrounding environment

    CERN Document Server

    Ishibashi, W

    2016-01-01

    Significant reservoirs of cool gas are observed in the circumgalactic medium (CGM) surrounding galaxies. The CGM is also found to contain substantial amounts of metals and dust, which require some transport mechanism. We consider AGN (active galactic nucleus) feedback-driven outflows based on radiation pressure on dust. Dusty gas is ejected when the central luminosity exceeds the effective Eddington luminosity for dust. We obtain that a higher dust-to-gas ratio leads to a lower critical luminosity, implying that the more dusty gas is more easily expelled. Dusty outflows can reach large radii with a range of velocities (depending on the outflowing shell configuration and the ambient density distribution) and may account for the observed CGM gas. In our picture, dust is required in order to drive AGN feedback, and the preferential expulsion of dusty gas in the outflows may naturally explain the presence of dust in the CGM. On the other hand, the most powerful AGN outflow events can potentially drive gas out of ...

  10. Chemical recycling of carbon dioxide to methanol and dimethyl ether: from greenhouse gas to renewable, environmentally carbon neutral fuels and synthetic hydrocarbons.

    Science.gov (United States)

    Olah, George A; Goeppert, Alain; Prakash, G K Surya

    2009-01-16

    Nature's photosynthesis uses the sun's energy with chlorophyll in plants as a catalyst to recycle carbon dioxide and water into new plant life. Only given sufficient geological time can new fossil fuels be formed naturally. In contrast, chemical recycling of carbon dioxide from natural and industrial sources as well as varied human activities or even from the air itself to methanol or dimethyl ether (DME) and their varied products can be achieved via its capture and subsequent reductive hydrogenative conversion. The present Perspective reviews this new approach and our research in the field over the last 15 years. Carbon recycling represents a significant aspect of our proposed Methanol Economy. Any available energy source (alternative energies such as solar, wind, geothermal, and atomic energy) can be used for the production of needed hydrogen and chemical conversion of CO(2). Improved new methods for the efficient reductive conversion of CO(2) to methanol and/or DME that we have developed include bireforming with methane and ways of catalytic or electrochemical conversions. Liquid methanol is preferable to highly volatile and potentially explosive hydrogen for energy storage and transportation. Together with the derived DME, they are excellent transportation fuels for internal combustion engines (ICE) and fuel cells as well as convenient starting materials for synthetic hydrocarbons and their varied products. Carbon dioxide thus can be chemically transformed from a detrimental greenhouse gas causing global warming into a valuable, renewable and inexhaustible carbon source of the future allowing environmentally neutral use of carbon fuels and derived hydrocarbon products.

  11. Novel experimental setup for time-of-flight mass spectrometry ion detection in collisions of anionic species with neutral gas-phase molecular targets.

    Science.gov (United States)

    Oller, J C; Ellis-Gibbings, L; da Silva, F Ferreira; Limão-Vieira, P; García, G

    We report a novel experimental setup for studying collision induced products resulting from the interaction of anionic beams with a neutral gas-phase molecular target. The precursor projectile was admitted into vacuum through a commercial pulsed valve, with the anionic beam produced in a hollow cathode discharge-induced plasma, and guided to the interaction region by a set of deflecting plates where it was made to interact with the target beam. Depending on the collision energy regime, negative and positive species can be formed in the collision region and ions were time-of-flight (TOF) mass-analysed. Here, we present data on O2 precursor projectile, where we show clear evidence of O(-) and O2(-) formation from the hollow cathode source as well as preliminary results on the interaction of these anions with nitromethane, CH3NO2. The negative ions formed in such collisions were analysed using time-of-flight mass spectrometry. The five most dominant product anions were assigned to H(-), O(-), NO(-), CNO(-) and CH3NO2(-).

  12. The small observed scale of AGN--driven outflows, and inside--out disc quenching

    CERN Document Server

    Zubovas, Kastytis

    2016-01-01

    Observations of massive outflows with detectable central AGN typically find them within radii $\\lesssim 10$ kpc. We show that this apparent size restriction is a natural result of AGN driving if this process injects total energy only of order the gas binding energy to the outflow, and the AGN varies over time (`flickers') as suggested in recent work. After the end of all AGN activity the outflow continues to expand to larger radii, powered by the thermal expansion of the remnant shocked AGN wind. We suggest that on average, outflows should be detected further from the nucleus in more massive galaxies. In massive gas--rich galaxies these could be several tens of kpc in radius. We also consider the effect that pressure of such outflows has on a galaxy disc. In moderately gas--rich discs, with gas-to-baryon fraction $< 0.2$, the outflow may induce star formation significant enough to be distinguished from quiescent by an apparently different normalisation of the Kennicutt-Schmidt law. The star formation enhan...

  13. The Relationship between the Dense Neutral and Diffuse Ionized Gas in the Thick Disks of Two Edge-on Spiral Galaxies

    Science.gov (United States)

    Rueff, Katherine M.; Howk, J. Christopher; Pitterle, Marissa; Hirschauer, Alec S.; Fox, Andrew J.; Savage, Blair D.

    2013-03-01

    We present high-resolution, optical images (BVI + Hα) of the multiphase interstellar medium (ISM) in the thick disks of the edge-on spiral galaxies NGC 4013 and NGC 4302. Our images from the Hubble Space Telescope (HST), Large Binocular Telescope, and WIYN 3.5 m telescope reveal an extensive population of filamentary dust absorption seen to z ~2-2.5 kpc. Many of these dusty thick disk structures have characteristics reminiscent of molecular clouds found in the Milky Way disk. Our Hα images show that the extraplanar diffuse ionized gas (DIG) in these galaxies is dominated by a smooth, diffuse component. The strongly filamentary morphologies of the dust absorption have no counterpart in the smoothly distributed Hα emission. We argue that the thick disk DIG and dust-bearing filaments trace physically distinct phases of the thick disk ISM, the latter tracing a dense, warm or cold neutral medium. The dense, dusty matter in the thick disks of spiral galaxies is largely tracing matter ejected from the thin disk via energetic feedback from massive stars. The high densities of the gas may be a result of converging gas flows. This dense material fuels some thick disk star formation, as evidenced by the presence of thick disk H II regions. Based on observations obtained with the NASA/ESA Hubble Space Telescope operated at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also, based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the US, Italy, and Germany. LBT Corporation partners are the University of Arizona, on behalf of the Arizona University System; Instituto Nazionale do Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam, and Heidelberg University; Ohio State University, and the Research Corporation, on

  14. Evolution and excitation conditions of outflows in high-mass star-forming regions

    CERN Document Server

    Sanchez-Monge, A; Cesaroni, R; Walmsley, C M; Codella, C; Beltran, M T; Pestalozzi, M; Molinari, S

    2013-01-01

    Theoretical models suggest that massive stars form via disk-mediated accretion, with bipolar outflows playing a fundamental role. A recent study toward massive molecular outflows has revealed a decrease of the SiO line intensity as the object evolves. The present study aims at characterizing the variation of the molecular outflow properties with time, and at studying the SiO excitation conditions in outflows associated with massive YSOs. We used the IRAM30m telescope to map 14 massive star-forming regions in the SiO(2-1), SiO(5-4) and HCO+(1-0) outflow lines, and in several dense gas and hot core tracers. Hi-GAL data was used to improve the spectral energy distributions and the L/M ratio, which is believed to be a good indicator of the evolutionary stage of the YSO. We detect SiO and HCO+ outflow emission in all the sources, and bipolar structures in six of them. The outflow parameters are similar to those found toward other massive YSOs. We find an increase of the HCO+ outflow energetics as the object evolve...

  15. Radiation-Hydrodynamic Simulations of Massive Star Formation with Protostellar Outflows

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, A J; Klein, R I; Krumholz, M R; McKee, C F

    2011-03-02

    We report the results of a series of AMR radiation-hydrodynamic simulations of the collapse of massive star forming clouds using the ORION code. These simulations are the first to include the feedback effects protostellar outflows, as well as protostellar radiative heating and radiation pressure exerted on the infalling, dusty gas. We find that that outflows evacuate polar cavities of reduced optical depth through the ambient core. These enhance the radiative flux in the poleward direction so that it is 1.7 to 15 times larger than that in the midplane. As a result the radiative heating and outward radiation force exerted on the protostellar disk and infalling cloud gas in the equatorial direction are greatly diminished. The simultaneously reduces the Eddington radiation pressure barrier to high-mass star formation and increases the minimum threshold surface density for radiative heating to suppress fragmentation compared to models that do not include outflows. The strength of both these effects depends on the initial core surface density. Lower surface density cores have longer free-fall times and thus massive stars formed within them undergo more Kelvin contraction as the core collapses, leading to more powerful outflows. Furthermore, in lower surface density clouds the ratio of the time required for the outflow to break out of the core to the core free-fall time is smaller, so that these clouds are consequently influenced by outflows at earlier stages of collapse. As a result, outflow effects are strongest in low surface density cores and weakest in high surface density one. We also find that radiation focusing in the direction of outflow cavities is sufficient to prevent the formation of radiation pressure-supported circumstellar gas bubbles, in contrast to models which neglect protostellar outflow feedback.

  16. New Insights into AGN Mass Outflows: Detailed Study of the Spectral Properties of NGC 4151

    Science.gov (United States)

    Denes Couto, Jullianna

    2017-08-01

    Active Galactic Nuclei (AGNs) exist in a few percent of all massive galaxies. It is believed that AGNs are powered by accretion of matter onto a supermassive black hole (SMBH), generating in the process huge amounts of radiation that span the entire electromagnetic spectrum. In turn, this also triggers the so-called AGN Feedback phenomenon, by inducing the formation of accretion disk winds (or outflows) that accelerate highly ionized gas outwards and affect the intergalactic medium of the host galaxy, reducing star formation rates and preventing bulge growth. It has been suggested that a dominant component of mass outflows is observable in the X-rays, and there are a limited number of detailed studies of single objects for which the relation between outflows and power of the central engine can be determined directly. The Seyfert 1.5 galaxy NGC 4151 is a great study candidate, given its proximity (14.077 Mpc, z = 0.0033), X-ray brightness and orientation. Over the past decades, it has been the target of many single and multiwavelength observations, and its heavily absorbed X-ray spectrum and complex absorption features have been extensively stud- ied and characterized. I have investigated the relationship between the long term X-ray spectral variability in and its intrinsic absorption, by comparing our 2014 simultaneous ultraviolet/X-Ray observations taken with Hubble Space Telescope Imaging Spectrometer (STIS) Echelle and Chandra High Energy Transmission Grating Spectrometer (HETGS) with archival observations from Chandra, XMM-Newton and Suzaku. The observations were divided into "high" and "low" flux states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. The X-ray model consists of a broken powerlaw, neutral reflection and two dominant absorption components, a high and a low ionization component, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes

  17. Fast outflows and star formation quenching in quasar host galaxies

    CERN Document Server

    Carniani, S; Maiolino, R; Balmaverde, B; Brusa, M; Cano-Díaz, M; Cicone, C; Comastri, A; Cresci, G; Fiore, F; Feruglio, C; La Franca, F; Mainieri, V; Mannucci, F; Nagao, T; Netzer, H; Piconcelli, E; Risaliti, G; Schneider, R; Shemmer, O

    2016-01-01

    Negative feedback from active galactic nuclei (AGN) is considered a key mechanism in shaping galaxy evolution. Fast, extended outflows are frequently detected in the AGN host galaxies at all redshifts and luminosities, both in ionised and molecular gas. However, these outflows are only "potentially" able to quench star formation and we are still missing a decisive evidence of negative feedback in action. Here we present Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) H- and K-band integral-field spectroscopic observations of two quasars at $z\\sim$2.4 characterised by fast, extended outflows detected through the [OIII]$\\lambda$5007 line (Carniani et al. 2015). The high signal-to-noise ratio of our observations allows us to identify faint narrow (FWHM $< 500$ km/s), and spatially extended components in [OIII]$\\lambda$5007 and H$\\alpha$ emission associated with star formation in the host galaxy. Such star-formation powered emission is spatially anti-correlated with the fast outflow...

  18. Methanol Maser Associated Outflows: Detection statistics and properties

    CERN Document Server

    de Villiers, H M; Thompson, M A; Ellingsen, S P; Urquhart, J S; Breen, S L; Burton, M G; Csengeri, T; Ward-Thompson, D

    2014-01-01

    We have selected the positions of 54 6.7GHz methanol masers from the Methanol Multibeam Survey catalogue, covering a range of longitudes between $20^{\\circ}$ and $34^{\\circ}$ of the Galactic Plane. These positions were mapped in the J=3-2 transition of both the $\\rm{^{13}CO}$ and $\\rm{C^{18}O}$ lines. A total of 58 $\\rm{^{13}CO}$ emission peaks are found in the vicinity of these maser positions. We search for outflows around all $\\rm{^{13}CO}$ peaks, and find evidence for high-velocity gas in all cases, spatially resolving the red and blue outflow lobes in 55 cases. Of these sources, 44 have resolved kinematic distances, and are closely associated with the 6.7GHz masers, a sub-set referred to as Methanol Maser Associated Outflows (MMAOs). We calculate the masses of the clumps associated with each peak using 870 $\\rm{\\mu m}$ continuum emission from the ATLASGAL survey. A strong correlation is seen between the clump mass and both outflow mass and mechanical force, lending support to models in which accretion is...

  19. Quantifying the Multiphase Galactic Outflows Driven by Supernovae

    Science.gov (United States)

    Li, Miao; Bryan, Greg; Ostriker, Jeremiah P.

    2017-01-01

    Galactic outflows are ubiquitously observed in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SN) play a key role in driving the outflows, but there is no consensus as to how much energy, mass and metals they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SN-driven outflows from stratified media. We study various conditions along the Kennicutt-Schmidt relation, and examine the loading factors of energy, mass and metals as a function of the star formation rate. We find that the hot phase, being fast and metal-enriched, would have a broad impact on the circum-galactic medium. We explore how various physical processes, including SN scale height, photoelectric heating, external gravitational field and SN rate, affect the loading factors. We find that the mass loading factor can achieve unity for a gas surface density similar to the solar neighborhood, but is lower for higher densities. The mass loading is in general a factor of a few smaller than what is currently adopted in cosmological simulations. SN-driven outflows are expected to efficiently transport out of the galaxies both energy and metals.

  20. Protostellar Jet and Outflow in the Collapsing Cloud Core

    CERN Document Server

    Machida, Masahiro N; Matsumoto, Tomoaki

    2009-01-01

    We investigate the driving mechanism of outflows and jets in star formation process using resistive MHD nested grid simulations. We found two distinct flows in the collapsing cloud core: Low-velocity outflows (sim 5 km/s) with a wide opening angle, driven from the first adiabatic core, and high-velocity jets (sim 50 km/s) with good collimation, driven from the protostar. High-velocity jets are enclosed by low-velocity outflow. The difference in the degree of collimation between the two flows is caused by the strength of the magnetic field and configuration of the magnetic field lines. The magnetic field around an adiabatic core is strong and has an hourglass configuration. Therefore, the low-velocity outflow from the adiabatic core are driven mainly by the magnetocentrifugal mechanism and guided by the hourglass-like field lines. In contrast, the magnetic field around the protostar is weak and has a straight configuration owing to Ohmic dissipation in the high-density gas region. Therefore, high-velocity jet ...

  1. Electron super-rich radicals in the gas phase. A neutralization-reionization mass spectrometric and ab initio/RRKM study of diaminohydroxymethyl and triaminomethyl radicals.

    Science.gov (United States)

    Hao, Changtong; Seymour, Jennifer L; Turecek, Frantisek

    2007-09-13

    Diaminohydroxymethyl (1) and triaminomethyl (2) radicals were generated by femtosecond collisional electron transfer to their corresponding cations (1+ and 2+, respectively) and characterized by neutralization-reionization mass spectrometry and ab initio/RRKM calculations at correlated levels of theory up to CCSD(T)/aug-cc-pVTZ. Ion 1+ was generated by gas-phase protonation of urea which was predicted to occur preferentially at the carbonyl oxygen with the 298 K proton affinity that was calculated as PA = 875 kJ mol-1. Upon formation, radical 1 gains vibrational excitation through Franck-Condon effects and rapidly dissociates by loss of a hydrogen atom, so that no survivor ions are observed after reionization. Two conformers of 1, syn-1 and anti-1, were found computationally as local energy minima that interconverted rapidly by inversion at one of the amine groups with a <7 kJ mol-1 barrier. The lowest energy dissociation of radical 1 was loss of the hydroxyl hydrogen atom from anti-1 with ETS = 65 kJ mol-1. The other dissociation pathways of 1 were a hydroxyl hydrogen migration to an amine group followed by dissociation to H2N-C=O* and NH3. Ion 2+ was generated by protonation of gas-phase guanidine with a PA = 985 kJ mol-1. Electron transfer to 2+ was accompanied by large Franck-Condon effects that caused complete dissociation of radical 2 by loss of an H atom on the experimental time scale of 4 mus. Radicals 1 and 2 were calculated to have extremely low ionization energies, 4.75 and 4.29 eV, respectively, which belong to the lowest among organic molecules and bracket the ionization energy of atomic potassium (4.34 eV). The stabilities of amino group containing methyl radicals, *CH2NH2, *CH(NH2)2, and 2, were calculated from isodesmic hydrogen atom exchange with methane. The pi-donating NH2 groups were found to increase the stability of the substituted methyl radicals, but the stabilities did not correlate with the radical ionization energies.

  2. The SINS/zC-SINF survey of z~2 galaxy kinematics: Outflow properties

    CERN Document Server

    Newman, Sarah F; Forster-Schreiber, Natascha; Griffin, Kristin Shapiro; Mancini, Chiara; Lilly, Simon J; Renzini, Alvio; Bouche, Nicolas; Burkert, Andreas; Buschkamp, Peter; Carollo, C Marcella; Cresci, Giovanni; Davies, Ric; Eisenhauer, Frank; Genel, Shy; Hicks, Erin K S; Kurk, Jaron; Lutz, Dieter; Naab, Thorsten; Peng, Yingjie; Sternberg, Amiel; Tacconi, Linda J; Vergani, Daniela; Wuyts, Stijn; Zamorani, Gianni

    2012-01-01

    Based on SINFONI Ha, [NII] and [SII] AO data of 30 z \\sim 2 star-forming galaxies (SFGs) from the SINS and zcSINF surveys, we find a strong correlation of the Ha broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 Msun yr^-1 kpc^-2. Above this threshold, we find that SFGs with logm_\\ast>10 have similar or perhaps greater wind mass loading factors (eta = Mdotout/SFR) and faster outflow velocities than lower mass SFGs. This trend suggests that the majority of outflowing gas at z \\sim 2 may derive from high-mass SFGs, and that the z \\sim 2 mass-metallicity relation is driven more by dilution of enriched gas in the galaxy gas reservoir than by the efficiency of outflows. The mass loading factor is also correlated with the SFR and inclination, such that more star-forming and face-on galaxies launch more powerful outflows. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to ...

  3. Overconsumption, outflows and the quenching of satellite galaxies

    CERN Document Server

    McGee, Sean L; Balogh, Michael L

    2014-01-01

    The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events -- either direct stripping of the disk (ram pressure stripping) or the extended gas halo (strangulation) -- or from internally-driven star formation outflows via overconsumption. The observed timescales show significant deviation from the evolution expec...

  4. A young bipolar outflow from IRAS15398-3359

    Science.gov (United States)

    Bjerkeli, Per; Jørgensen, Jes K.

    2015-08-01

    The Class 0 protostar IRAS 15398-3359 is located in the Lupus I cloud at a distance of 155 pc. The source is known to harbour a molecular outflow, but the region has not attracted much interest until recently. IRAS 15398 is known to show interesting chemical signatures and being one of the very nearby, young outflow sources makes it an excellent target for detailed studies of the gas kinematics of different species.We present observations of several molecular species, carried out with the Submillimeter Array and ALMA, towards the IRAS 15398 outflow. The analysis of CO emission show obvious signs of episodic mass ejections, with a dynamical time scale between the knots in the jet, of the order 100 years. This is consistent with recent ALMA results where luminosity outbursts are estimated to occur on similar time-scales. The physical properties of the outflow, such as mass, momentum, momentum rate, mechanical luminosity, kinetic energy and mass-loss rate are estimated at relatively low values. We argue that this source is of a very young age, possibly younger than ~1000 years. This is consistent with recent studies of the kinematics of the inner envelope/disk. The observed line profiles were compared to full 3D radiative transfer models of the source, constructed with the Line Modelling Engine (LIME). The observed line shapes can only be understood when considering several distinctly different physical components, viz. the outflow cavity, the infalling envelope and the surrounding cloud material. This allows us to put quantitative constraints on the kinematics of the material close to the central source.

  5. How stellar feedback simultaneously regulates star formation and drives outflows

    CERN Document Server

    Hayward, Christopher C

    2015-01-01

    We present an analytic model for how momentum deposition from stellar feedback simultaneously regulates star formation and drives outflows in a turbulent interstellar medium (ISM). Because the ISM is turbulent, a given patch of ISM exhibits sub-patches with a range of surface densities. The high-density patches are 'pushed' by feedback, thereby driving turbulence and self-regulating local star formation. Sufficiently low-density patches, however, are accelerated to above the escape velocity before the region can self-adjust and are thus vented as outflows. In the turbulent-pressure-supported regime, when the gas fraction is $\\gtrsim 0.3$, the ratio of the turbulent velocity dispersion to the circular velocity is sufficiently high that at any given time, of order half of the ISM has surface density less than the critical value and thus can be blown out on a dynamical time. The resulting outflows have a mass-loading factor ($\\eta \\equiv M_{\\rm out}/M_{\\star}$) that is inversely proportional to the gas fraction ...

  6. On the Formation of Molecular Clumps in QSO Outflows

    CERN Document Server

    Ferrara, Andrea

    2016-01-01

    We study the origin of the cold molecular clumps in quasar outflows, recently detected in CO and HCN emission. We first describe the physical properties of such radiation-driven outflows and show that a transition from a momentum- to an energy-driven flow must occur at a radial distance of R ~ 0.25 kpc. During this transition, the shell of swept up material fragments due to Rayleigh-Taylor instabilities, but these clumps contain little mass and are likely to be rapidly ablated by the hot gas in which they are immersed. We then explore an alternative scenario in which clumps form from thermal instabilities at R >~ 1 kpc, possibly containing enough dust to catalyze molecule formation. We investigate this processes with 3D two-fluid (gas+dust) numerical simulations of a kpc^3 patch of the outflow, including atomic and dust cooling, thermal conduction, dust sputtering, and photoionization from the QSO radiation field. In all cases, dust grains are rapidly destroyed in ~10,000 years; and while some cold clumps for...

  7. A young bipolar outflow from IRAS 15398-3359

    CERN Document Server

    Bjerkeli, P; Brinch, C

    2016-01-01

    Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry, as well as the kinematical information allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. We aim at determining the spatial distribution of different species, of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim at determining the nature of the infalling and outflowing gas in the system. We also aim at determining the physical properties of the outflow. Maps from the Sub-Millimeter Array reveal the spatial distribution of the gaseous emission toward IRAS15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all...

  8. Unconventional aqueous humor outflow: A review.

    Science.gov (United States)

    Johnson, Mark; McLaren, Jay W; Overby, Darryl R

    2017-05-01

    Aqueous humor flows out of the eye primarily through the conventional outflow pathway that includes the trabecular meshwork and Schlemm's canal. However, a fraction of aqueous humor passes through an alternative or 'unconventional' route that includes the ciliary muscle, supraciliary and suprachoroidal spaces. From there, unconventional outflow may drain through two pathways: a uveoscleral pathway where aqueous drains across the sclera to be resorbed by orbital vessels, and a uveovortex pathway where aqueous humor enters the choroid to drain through the vortex veins. We review the anatomy, physiology and pharmacology of these pathways. We also discuss methods to determine unconventional outflow rate, including direct techniques that use radioactive or fluorescent tracers recovered from tissues in the unconventional pathway and indirect methods that estimate unconventional outflow based on total outflow over a range of pressures. Indirect methods are subject to a number of assumptions and generally give poor agreement with tracer measurements. We review the variety of animal models that have been used to study conventional and unconventional outflow. The mouse appears to be a promising model because it captures several aspects of conventional and unconventional outflow dynamics common to humans, although questions remain regarding the magnitude of unconventional outflow in mice. Finally, we review future directions. There is a clear need to develop improved methods for measuring unconventional outflow in both animals and humans. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The COMPLETE Survey of Outflows in Perseus

    CERN Document Server

    Arce, Hector G; Goodman, Alyssa A; Pineda, Jaime E; Halle, Michael W; 10.1088/0004-637X/715/2/1170

    2010-01-01

    We present a study on the impact of molecular outflows in the Perseus molecular cloud complex using the COMPLETE survey large-scale 12CO(1-0) and 13CO(1-0) maps. We used three-dimensional isosurface models generated in RA-DEC-Velocity space to visualize the maps. This rendering of the molecular line data allowed for a rapid and efficient way to search for molecular outflows over a large (~ 16 sq. deg.) area. Our outflow-searching technique detected previously known molecular outflows as well as new candidate outflows. Most of these new outflow-related high-velocity features lie in regions that have been poorly studied before. These new outflow candidates more than double the amount of outflow mass, momentum, and kinetic energy in the Perseus cloud complex. Our results indicate that outflows have significant impact on the environment immediately surrounding localized regions of active star formation, but lack the energy needed to feed the observed turbulence in the entire Perseus complex. This implies that oth...

  10. Morphologies of protostellar outflows: An ALMA view

    CERN Document Server

    Peters, Thomas; Seifried, Daniel; Banerjee, Robi; Klessen, Ralf S

    2014-01-01

    The formation of stars is usually accompanied by the launching of protostellar outflows. Observations with the Atacama Large Millimetre/sub-millimetre Array (ALMA) will soon revolutionalise our understanding of the morphologies and kinematics of these objects. In this paper, we present synthetic ALMA observations of protostellar outflows based on numerical magnetohydrodynamic collapse simulations. We find significant velocity gradients in our outflow models and a very prominent helical structure within the outflows. We speculate that the disk wind found in the ALMA Science Verification Data of HD 163296 presents a first instance of such an observation.

  11. The structure of C5H 5RFe (+) (R = F, Cl, Br, I, O, OH, OCH3, C 6H 5, H) ions in the gas phase and the generation of their neutral counterparts by neutralization-reionization mass spectrometry.

    Science.gov (United States)

    Zagorevskii, D V; Holmes, J L; Zverev, D V; Orlova, T Y; Nekrasov, Y S

    1995-12-01

    The structure of C5H5FeR(+·) ions was studied by tandem mass spectromerry that included the neutralization-reionization (NR) method. Halogen-containing species (R = F, Cl, Br, I) showed fragmentation that was consistent with a structure that has the cyclopentadienyl ring and R as separate ligands at the metal atom (structure A). This structure also was identified for C5H5FeO(+) and CpFeOH(+·) ions, but these species also easily isomerized to metal-cyclopentadiene structure, RC5H5Fe(+·) (B), followed by hydrogen rearrangement(s) and CO loss. B was the dominant structure of C5H5FeH(+·) and C5H5FeC6H 5 (+·) ions. All ions that have structure A showed recovery signals in their NR mass spectra that indicated that their stable neutral counterparts were generated. The NR mass spectra also provided complementary information about the structure of ions before neutralization and after reionization.

  12. The SiO outflow from IRAS 17233-3603 at high resolution

    CERN Document Server

    Klaassen, P D; Leurini, S; Zapata, L A

    2014-01-01

    Context: Jets and outflows are key ingredients in the formation of stars across the mass spectrum. In clustered regions, understanding powering sources and outflow components poses a significant problem. Aims: To understand the dynamics in the outflow(s) from a cluster in the process of forming massive stars. Methods: We use new VLA observations of the molecular gas (SiO, CS, OCS and \\molec) in the massive star forming region IRAS 17233-3606 which contains a number of HII regions. We compare these observations to previously published molecular data for this source in order to get a holistic view of the outflow dynamics. Results:We find that the dynamics of the various species can be explained by a single large scale ($\\sim 0.15$ pc) outflow when compared to the sizes of the HII regions, with the different morphologies of the blue and red outflow components explained with respect to the morphology of the surrounding envelope. We further find that the direction of the velocity gradients seen in OCS and \\molec a...

  13. AGN Feedback Driven Molecular Outflow in NGC 1266

    CERN Document Server

    Alatalo, K; Graves, G; Deustua, S; Wrobel, J; Young, L M; Davis, T A; Bureau, M; Bayet, E; Blitz, L; Bois, M; Bournaud, F; Cappellari, M; Davies, R L; de Zeeuw, P T; Emsellem, E; Khochfar, S; Krajnovic, D; Kuntschner, H; Martin, S; McDermid, R M; Morganti, R; Naab, T; Oosterloo, T; Sarzi, M; Scott, N; Serra, P; Weijmans, A

    2012-01-01

    NGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high bright- ness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies.

  14. Observing the onset of outflow collimation in a massive protostar

    CERN Document Server

    Carrasco-González, C; Cantó, J; Curiel, S; Surcis, G; Vlemmings, W H T; van Langevelde, H J; Goddi, C; Anglada, G; Kim, S -W; Kim, J -S; Gómez, J F

    2015-01-01

    The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic, ionized wind whose morphology evolves as it moves within a toroidal density stratification.

  15. Developing the Next Generation of Tools for Simulating Galaxy Outflows

    Science.gov (United States)

    Scannapieco, Evan

    Outflows are observed in starbursting galaxies of all masses and at all cosmological epochs. They play a key role throughout the history of the Universe: shaping the galaxy mass-metallicity relation, drastically affecting the content and number density of dwarf galaxies, and transforming the chemical composition of the intergalactic medium. Yet, a complete model of galaxy out ows has proven to be elusive, as it requires both a better understanding of the evolution of the turbulent, multiphase gas in and around starbursting galaxies, and better tools to reproduce this evolution in galaxy-scale simulations. Here we propose to conduct a detailed series of numerical simulations designed to help develop such next-generation tools for the simulation of galaxy outflows. The program will consist of three types of direct numerical simulations, each of which will be targeted to allow galaxy-scale simulations to more accurately model key microphysical processes and their observational consequences. Our first set of simulations will be targeted at better modeling the starbursting interstellar medium (ISM) from which galaxy outflows are driven. The surface densities in starbursting galaxies are much larger than those in the Milky Way, resulting in larger gravitational accelerations and random velocities exceeding 30 or even 100 km/s. Under these conditions, the thermal stability of the ISM is changed dramatically, due to the sharp peak in gas cooling efficiency at H 200,000 K. Our simulations will carefully quantify the key ways in which this medium differs from the local ISM, and the consequences of these differences for when, where, and how outflows are driven. A second set of simulations will be targeted at better modeling the observed properties of rapidly cooling, highly turbulent gas. Because gas cooling in and around starbursts is extremely efficient, turbulent motions are often supersonic, which leads to a distribution of ionization states that is vastly different than

  16. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  17. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  18. Unified Models of Molecular Emission from Class 0 Protostellar Outflow Sources

    CERN Document Server

    Rawlings, J M C; Carolan, P B

    2013-01-01

    Low mass star-forming regions are more complex than the simple spherically symmetric approximation that is often assumed. We apply a more realistic infall/outflow physical model to molecular/continuum observations of three late Class 0 protostellar sources with the aims of (a) proving the applicability of a single physical model for all three sources, and (b) deriving physical parameters for the molecular gas component in each of the sources. We have observed several molecular species in multiple rotational transitions. The observed line profiles were modelled in the context of a dynamical model which incorporates infall and bipolar outflows, using a three dimensional radiative transfer code. This results in constraints on the physical parameters and chemical abundances in each source. Self-consistent fits to each source are obtained. We constrain the characteristics of the molecular gas in the envelopes as well as in the molecular outflows. We find that the molecular gas abundances in the infalling envelope ...

  19. Herschel reveals a molecular outflow in a z = 2.3 ULIRG

    CERN Document Server

    George, Richard; Smail, Ian; Swinbank, Mark; Hopwood, Rosalind; Stanley, Fiona; Swinyard, Bruce; Valtchanov, Ivan; van der Werf, Paul

    2014-01-01

    We report the results from a 19-hr integration with the SPIRE Fourier Transform Spectrometer aboard the Herschel Space Observatory which has revealed the presence of a molecular outflow from the Cosmic Eyelash (SMM J2135-0102, hereafter SMMJ2135) via the detection of blueshifted OH absorption. Detections of several fine-structure emission lines indicate low-excitation HII regions contribute strongly to the [CII] luminosity in this z = 2.3 ULIRG. The OH feature suggests a maximum wind velocity of 700 km/s and outflow rate of ~60 Msun/yr. This is lower than the expected escape velocity of the host dark matter halo, ~1000 km/s. A large fraction of the available molecular gas could thus be converted into stars via a burst protracted by the resulting gas fountain, until an AGN-driven outflow can eject the remaining gas.

  20. A fast and long-lived outflow from the supermassive black hole in NGC 5548

    CERN Document Server

    Kaastra, J S; Cappi, M; Mehdipour, M; Petrucci, P -O; Steenbrugge, K C; Arav, N; Behar, E; Bianchi, S; Boissay, R; Branduardi-Raymont, G; Chamberlain, C; Costantini, E; Ely, J C; Ebrero, J; Di Gesu, L; Harrison, F A; Kaspi, S; Malzac, J; De Marco, B; Matt, G; Nandra, K; Paltani, S; Person, R; Peterson, B M; Pinto, C; Ponti, G; Nuñez, F Pozo; De Rosa, A; Seta, H; Ursini, F; de Vries, C P; Walton, D J; Whewell, M

    2014-01-01

    Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas never seen before. It blocks 90% of the soft X-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.

  1. An ultra-dense fast outflow in a quasar at z=2.4

    CERN Document Server

    Williams, R J; Krongold, Y; Carniani, S; Cresci, G; Mannucci, F; Marconi, A

    2016-01-01

    We present Adaptive Optics assisted near-IR integral field spectroscopic observations of a luminous quasar at $z = 2.4$, previously observed as the first known example at high redshift of large scale quasar-driven outflow quenching star formation in its host galaxy. The nuclear spectrum shows broad and blueshifted H$\\beta$ in absorption, which is tracing outflowing gas with high densities ($>10^8$ - $10^9$ cm$^{-3}$) and velocities in excess of 10,000 km s$^{-1}$. The properties of the outflowing clouds (covering factor, density, column density and inferred location) indicate that they likely originate from the Broad Line Region. The energetics of such nuclear regions are consistent with that observed in the large scale outflow, supporting models in which quasar driven outflows originate from the nuclear region and are energy conserving. We note that the asymmetric profile of both the H$\\beta$ and H$\\alpha$ emission lines is likely due to absorption by the dense outflowing gas along the line of sight. This ou...

  2. A Highly Collimated, Young and Fast CO(2-1) Outflow in OMC1 South

    CERN Document Server

    Zapata, L A; Ho, P T P; Zhang, Q; Qi, C; Kurtz, S E; Zapata, Luis A.; Rodriguez, Luis F.; Ho, Paul T.P.; Zhang, Qizhou; Qi, Chunhua

    2005-01-01

    We present high angular resolution (~ 1''), sensitive CO(2-1) line observations of the region OMC1 South in the Orion Nebula made using the Submillimeter Array (SMA). We detect the CO(2-1) high velocity outflow that was first found by Rodriguez-Franco et al. (1999a) with the IRAM 30 m. Our observations resolve the outflow, whose velocity-integrated emission has a deconvolved width of 0.89'' \\pm 0.06'' (490 AU) and a projected length of ~ 48'' (21,000 AU) with very high redshifted and blueshifted gas with velocities of about \\pm 80 km/s. This outflow is among the most collimated (~ 3 degrees) and youngest outflows (600 yr) that have been reported. The data show that this collimated outflow has been blowing in the same direction during the last 600 yr. At high velocities, the CO(2-1) outflow traces an extremely collimated jet, while at lower velocities the CO emission traces an envelope possibly produced by entrainment of ambient gas. Furthermore, we also detect for the first time a millimeter wavelength contin...

  3. An origin for multiphase gas in galactic winds and haloes

    Science.gov (United States)

    Thompson, Todd A.; Quataert, Eliot; Zhang, Dong; Weinberg, David H.

    2016-01-01

    The physical origin of high-velocity cool gas seen in galactic winds remains unknown. Following work by B. Wang, we argue that radiative cooling in initially hot thermally-driven outflows can produce fast neutral atomic and photoionized cool gas. The inevitability of adiabatic cooling from the flow's initial 107-108 K temperature and the shape of the cooling function for T ≲ 107 K imply that outflows with hot gas mass-loss rate relative to star formation rate of β =dot{M}_hot/dot{M}_star ≳ 0.5 cool radiatively on scales ranging from the size of the energy injection region to tens of kpc. We highlight the β and star formation rate surface density dependence of the column density, emission measure, radiative efficiency, and velocity. At rcool, the gas produces X-ray and then UV/optical line emission with a total power bounded by ˜10-2 L⋆ if the flow is powered by steady-state star formation with luminosity L⋆. The wind is thermally unstable at rcool, potentially leading to a multiphase medium. Cooled winds decelerate significantly in the extended gravitational potential of galaxies. The cool gas precipitated from hot outflows may explain its prevalence in galactic haloes. We forward a picture of winds whereby cool clouds are initially accelerated by the ram pressure of the hot flow, but are rapidly shredded by hydrodynamical instabilities, thereby increasing β, seeding radiative and thermal instability, and cool gas rebirth. If the cooled wind shocks as it sweeps up the circumgalactic medium, its cooling time is short, thus depositing cool gas far out into the halo. Finally, conduction can dominate energy transport in low-β hot winds, leading to flatter temperature profiles than otherwise expected, potentially consistent with X-ray observations of some starbursts.

  4. Neutral particle lithography

    Science.gov (United States)

    Craver, Barry Paul

    Neutral particle lithography (NPL) is a high resolution, proximity exposure technique where a broad beam of energetic neutral particles floods a stencil mask and transmitted beamlets transfer the mask pattern to resist on a substrate, such that each feature is printed in parallel, rather than in the serial manner of electron beam lithography. It preserves the advantages of ion beam lithography (IBL), including extremely large depth-of-field, sub-5 nm resist scattering, and the near absence of diffraction, yet is intrinsically immune to charge-related artifacts including line-edge roughness and pattern placement errors due to charge accumulation on the mask and substrate. In our experiments, a neutral particle beam is formed by passing an ion beam (e.g., 30 keV He+) through a high pressure helium gas cell (e.g., 100 mTorr) to convert the ions to energetic neutrals through charge transfer scattering. The resolution of NPL is generally superior to that of IBL for applications involving insulating substrates, large proximity gaps, and ultra-small features. High accuracy stepped exposures with energetic neutral particles, where magnetic or electrostatic deflection is impossible, have been obtained by clamping the mask to the wafer, setting the proximity gap with a suitable spacer, and mechanically inclining the mask/wafer stack relative to the beam. This approach is remarkably insensitive to vibration and thermal drift; nanometer scale image offsets have been obtained with +/-2 nm placement accuracy for experiments lasting over one hour. Using this nanostepping technique, linewidth versus dose curves were obtained, from which the NPL lithographic blur was determined as 4.4+/-1.4 nm (1sigma), which is 2-3 times smaller than the blur of electron beam lithography. Neutral particle lithography has the potential to form high density, periodic patterns with sub-10 nm resolution.

  5. NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows

    CERN Document Server

    Di Cintio, Arianna; Dutton, Aaron A; Macciò, Andrea V; Obreja, Aura C; Dekel, Avishai

    2016-01-01

    We address the origin of Ultra-Diffuse Galaxies (UDGs), which have stellar masses typical of dwarf galaxies but effective radii of Milky Way-sized objects. Their formation mechanism, and whether they are failed $\\rm L_{\\star}$ galaxies or diffuse dwarfs, are challenging issues. Using zoom-in cosmological simulations from the NIHAO project, we show that UDG analogues form naturally in medium-mass haloes due to episodes of gas outflows associated with star formation. The simulated UDGs live in isolated haloes of masses $10^{10-11}\\rm M_{\\odot}$, have stellar masses of $10^{7-8.5}\\rm M_{\\odot}$, effective radii larger than 1 kpc and dark matter cores. They show a broad range of colors, an average S\\'ersic index of 0.83, a typical distribution of halo spin and concentration, and a non-negligible HI gas mass of $10^{7-9}\\rm M_{\\odot}$, which correlates with the extent of the galaxy. Gas availability is crucial to the internal processes that form UDGs: feedback driven gas outflows, and subsequent dark matter and st...

  6. Intergalactic Magnetic Fields from Quasar Outflows

    CERN Document Server

    Furlanetto, S; Furlanetto, Steven; Loeb, Abraham

    2001-01-01

    Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and calculate their distribution as a function of size and magnetic field strength at different redshifts. We generically find that by a redshift z=3, about 5-20% of the IGM volume is filled by magnetic fields with an energy density >10% of the mean thermal energy density of a photo-ionized IGM (at T=10^4 K). As massive galaxies and X-ray clusters condense out of the magnetized IGM, the adiabatic compression of the magnetic field could result in the field strength observed in these systems without a need for further dynamo amplification. The intergalactic magnetic field could also provide a nonthermal contribution to the pressure of the photo-ionized gas that may account for the claimed discrepancy between the simulated and observed Doppler width distributions of the Ly-al...

  7. Simulating galactic outflows with kinetic supernova feedback

    CERN Document Server

    Vecchia, Claudio Dalla

    2008-01-01

    Feedback from star formation is thought to play a key role in the formation and evolution of galaxies, but its implementation in cosmological simulations is currently hampered by a lack of numerical resolution. We present and test a sub-grid recipe to model feedback from massive stars in cosmological smoothed particle hydrodynamics simulations. The energy is distributed in kinetic form among the gas particles surrounding recently formed stars. The impact of the feedback is studied using a suite of high-resolution simulations of isolated disc galaxies embedded in dark halos with total mass 10^{10} and 10^{12} M_sol/h. We focus in particular on the effect of pressure forces within the disc, which we turn off temporarily in some of our runs to mimic a recipe that has been widely used in the literature. We find that (ram) pressure forces on expanding superbubbles determine both the structure of the disc and the development of large-scale outflows. Pressure forces exerted by expanding superbubbles puff up the disc...

  8. Metal enrichment by radiation pressure in active galactic nucleus outflows -- theory and observations

    CERN Document Server

    Baskin, Alexei

    2012-01-01

    Outflows from active galactic nuclei may be produced by absorption of continuum radiation by UV resonance lines of abundant metal ions, as observed in broad absorption line quasars (BALQs). The radiation pressure exerted on the metal ions is coupled to the rest of the gas through Coulomb collisions of the metal ions. We calculate the photon density and gas density which allow decoupling of the metal ions from the rest of the gas. These conditions may lead to an outflow composed mostly of the metal ions. We derive a method to constrain the metals/H ratio of observed UV outflows, based on the Ly {\\alpha} and Si iv {\\lambda}{\\lambda}1394, 1403 absorption profiles. We apply this method to an SDSS sample of BALQs to derive a handful of candidate outflows with a higher than solar metal/H ratio. This mechanism can produce ultra fast UV outflows, if a shield of the continuum source with a strong absorption edge is present.

  9. The Properties and Prevalence of Galactic Outflows at z ~ 1 in the Extended Groth Strip

    Science.gov (United States)

    Kornei, Katherine A.; Shapley, Alice E.; Martin, Crystal L.; Coil, Alison L.; Lotz, Jennifer M.; Schiminovich, David; Bundy, Kevin; Noeske, Kai G.

    2012-10-01

    We investigate galactic-scale outflowing winds in 72 star-forming galaxies at z ~ 1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering Si II, C IV, Fe II, Mg II, and Mg I lines in the rest-frame ultraviolet. Using Galaxy Evolution Explorer (GALEX), Hubble Space Telescope (HST), and Spitzer imaging available for the Extended Groth Strip, we examine galaxies on a per-object basis in order to better understand both the prevalence of galactic outflows at z ~ 1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from the centroids of Fe II interstellar absorption lines, are found to span the interval [-217, +155] km s-1. We find that ~40% (10%) of the sample exhibits blueshifted Fe II lines at the 1σ (3σ) level. We also measure maximal outflow velocities using the profiles of the Fe II and Mg II lines; we find that Mg II frequently traces higher velocity gas than Fe II. Using quantitative morphological parameters derived from the HST imaging, we find that mergers are not a prerequisite for driving outflows. More face-on galaxies also show stronger winds than highly inclined systems, consistent with the canonical picture of winds emanating perpendicular to galactic disks. In light of clumpy galaxy morphologies, we develop a new physically motivated technique for estimating areas corresponding to star formation. We use these area measurements in tandem with GALEX-derived star formation rates (SFRs) to calculate SFR surface densities. At least 70% of the sample exceeds an SFR surface density of 0.1 M ⊙ yr-1 kpc-2, the threshold necessary for driving an outflow in local starbursts. At the same time, the outflow detection fraction of only 40% in Fe II absorption provides further evidence for an outflow geometry that is not spherically symmetric. We see a ~3σ trend between outflow velocity and SFR surface density, but no significant trend

  10. Outflow and hot dust emission in high redshift quasars

    CERN Document Server

    Wang, Huiyuan; Zhang, Kai; Wang, Tinggui; Zhou, Hongyan; Zhang, Shaohua

    2013-01-01

    Correlations of hot dust emission with outflow properties are investigated, based on a large z~2 non-BAL quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near infrared (NIR) slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of CIV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, CIV regions are dominated by outflows so BAI and FWHM(CIV) can reliably reflect the general property and velocity of outflows, respectively. While in low Eddington ratio quasars, CIV lines are primarily emitted by virialized gas so BAI and FWHM(C...

  11. Constraining FeLoBAL outflows from absorption line variability

    CERN Document Server

    McGraw, S M; Hamann, F W; Capellupo, D M; Gallagher, S C; Brandt, W N

    2015-01-01

    FeLoBALs are a rare class of quasar outflows with low-ionization broad absorption lines (BALs), large column densities, and potentially large kinetic energies that might be important for `feedback' to galaxy evolution. In order to probe the physical properties of these outflows, we conducted a multiple-epoch, absorption line variability study of 12 FeLoBAL quasars spanning a redshift range between 0.7 and 1.9 over rest frame time-scales of approximately 10 d to 7.6 yr. We detect absorption line variability with greater than 8 sigma confidence in 3 out of the 12 sources in our sample over time-scales of 0.6 to 7.6 yr. Variable wavelength intervals are associated with ground and excited state Fe II multiplets, the Mg II 2796, 2803 doublet, Mg I 2852, and excited state Ni II multiplets. The observed variability along with evidence of saturation in the absorption lines favors transverse motions of gas across the line of sight (LOS) as the preferred scenario, and allows us to constrain the outflow distance from th...

  12. An Analytic Model of Galactic Winds and Mass Outflows

    Institute of Scientific and Technical Information of China (English)

    Cheng-Gang Shu; Hou-Jun Mo; Shu-De Mao

    2005-01-01

    Galactic winds and mass outflows are observed both in nearby starburst galaxies and in high-redshift star-forming galaxies. We develop a simple analytic model to understand the observed superwind phenomenon with a discussion of the model uncertainties. Our model is built upon the model of McKee & Ostriker for the interstellar medium. It allows one to predict how properties of a superwind,such as wind velocity and mass outflow rate, are related to properties of its star forming host galaxy, such as size, gas density and star formation rate. The model predicts a threshold of star formation rate density for the generation of observable galactic winds. Galaxies with more concentrated star formation activities produce superwinds with higher velocities. The predicted mass outflow rates are compara ble to (or slightly larger than) the corresponding star formation rates. We apply our model to both local starburst galaxies and high-redshift Lyman break galaxies, and find its predictions to be in good agreement with current observations. Our model is simple and so can be easily incorporated into numerical simulations and semi-analytical models of galaxy formation.

  13. Clustered star formation and outflows in AFGL 2591

    CERN Document Server

    Sanna, A; Carrasco-Gonzàlez, C; Menten, K M; Brunthaler, A; Moscadelli, L; Rygl, K L J

    2011-01-01

    We report on a detailed study of the water maser kinematics and radio continuum emission toward the most massive and young object in the star-forming region AFGL 2591. Our analysis shows at least two spatial scales of multiple star formation, one projected across 0.1 pc on the sky and another one at about 2000 AU from a ZAMS star of about 38 Solar masses. This young stellar object drives a powerful jet- and wind-driven outflow system with the water masers associated to the outflow walls, previously detected as a limb-brightened cavity in the NIR band. At about 1300 AU to the north of this object a younger protostar drives two bow shocks, outlined by arc-like water maser emission, at 200 AU either side of the source. We have traced the velocity profile of the gas that expands along these arc-like maser structures and compared it with the jet-driven outflow model. This analysis suggests that the ambient medium around the northern protostar is swept up by a jet-driven shock (>66 km/s) and perhaps a lower-velocit...

  14. GAS ACCRETION IS DOMINATED BY WARM IONIZED GAS IN MILKY WAY MASS GALAXIES AT z {approx} 0

    Energy Technology Data Exchange (ETDEWEB)

    Joung, M. Ryan; Putman, Mary E.; Bryan, Greg L.; Fernandez, Ximena; Peek, J. E. G., E-mail: moo@astro.columbia.edu [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)

    2012-11-10

    We perform high-resolution hydrodynamic simulations of a Milky Way mass galaxy in a fully cosmological setting using the adaptive mesh refinement code, Enzo, and study the kinematics of gas in the simulated galactic halo. We find that the gas inflow occurs mostly along filamentary structures in the halo. The warm-hot (10{sup 5} K 10{sup 6} K) ionized gases are found to dominate the overall mass accretion in the system (with M-dot = 3-5 M {sub Sun} yr{sup -1}) over a large range of distances, extending from the virial radius to the vicinity of the disk. Most of the inflowing gas (by mass) does not cool, and the small fraction that manages to cool does so primarily close to the galaxy (R {approx}< 100 kpc, with more pronounced cooling at smaller R), perhaps comprising the neutral gas that may be detectable as, e.g., high-velocity clouds. The neutral clouds are embedded within larger, accreting filamentary flows, and represent only a small fraction of the total mass inflow rate. The inflowing gas has relatively low metallicity (Z/Z {sub Sun} < 0.2). The outer layers of the filamentary inflows are heated due to compression as they approach the disk. In addition to the inflow, we find high-velocity, metal-enriched outflows of hot gas driven by supernova feedback. Our results are consistent with observations of halo gas at low z.

  15. Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy.

    Science.gov (United States)

    Geach, J E; Hickox, R C; Diamond-Stanic, A M; Krips, M; Rudnick, G H; Tremonti, C A; Sell, P H; Coil, A L; Moustakas, J

    2014-12-04

    Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and have typical scales of less than a kiloparsec. In at least some cases, input from active galactic nuclei is dynamically important, so pure stellar feedback (the momentum return into the interstellar medium) has been considered incapable of rapidly terminating star formation on galactic scales. Molecular gas has been detected outside the galactic plane of the archetypal starburst galaxy M82 (refs 4 and 5), but so far there has been no evidence that starbursts can propel substantial quantities of cold molecular gas to the same galactocentric radius (about 10 kiloparsecs) as the warmer gas that has been traced by metal ion absorbers in the circumgalactic medium. Here we report observations of molecular gas in a compact (effective radius 100 parsecs) massive starburst galaxy at redshift 0.7, which is known to drive a fast outflow of ionized gas. We find that 35 per cent of the total molecular gas extends approximately 10 kiloparsecs, and one-third of this extended gas has a velocity of up to 1,000 kilometres per second. The kinetic energy associated with this high-velocity component is consistent with the momentum flux available from stellar radiation pressure. This demonstrates that nuclear bursts of star formation are capable of ejecting large amounts of cold gas from the central regions of galaxies, thereby strongly affecting their evolution by truncating star formation and redistributing matter.

  16. DENSE CLUMPS AND CANDIDATES FOR MOLECULAR OUTFLOWS IN W40

    Energy Technology Data Exchange (ETDEWEB)

    Shimoikura, Tomomi; Dobashi, Kazuhito [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Nakamura, Fumitaka; Hara, Chihomi; Kawabe, Ryohei [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Tanaka, Tomohiro [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Shimajiri, Yoshito [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Sugitani, Kouji, E-mail: ikura@u-gakugei.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan)

    2015-06-20

    We report the results of the {sup 12}CO (J = 3−2) and HCO{sup +} (J = 4−3) observations of the W40 H ii region with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope (HPBW ≃ 22″) to search for molecular outflows and dense clumps. We found that the velocity field in the region is highly complex, consisting of at least four distinct velocity components at V{sub LSR} ≃ 3, 5, 7, and 10 km s{sup −1}. The ∼7 km s{sup −1} component represents the systemic velocity of cold gas surrounding the entire region, and causes heavy absorption in the {sup 12}CO spectra over the velocity range 6 ≲ V{sub LSR} ≲ 9 km s{sup −1}. The ∼5 and ∼10 km s{sup −1} components exhibit high {sup 12}CO temperature (≳40 K) and are found mostly around the H ii region, suggesting that these components are likely to be tracing dense gas interacting with the expanding shell around the H ii region. Based on the {sup 12}CO data, we identified 13 regions of high velocity gas, which we interpret as candidate outflow lobes. Using the HCO{sup +} data, we also identified six clumps and estimated their physical parameters. On the basis of the ASTE data and near-infrared images from 2MASS, we present an updated three-dimensional model of this region. In order to investigate molecular outflows in W40, the SiO (J = 1−0, v = 0) emission line and some other emission lines at 40 GHz were also observed with the 45 m telescope at the Nobeyama Radio Observatory, but they were not detected at the present sensitivity.

  17. The Hydrodynamics and Chemical Evolution of Starburst-driven Outflows

    CERN Document Server

    Tenorio-Tagle, G

    2002-01-01

    The hydrodynamics and intrinsic properties of galactic-scale gaseous outflows generated by violent starbursts are thoroughly discussed, taking into account the hot gas chemical evolution and radiative cooling. It is shown that the metallicity of superbubbles vary with time and can easily exceed the solar value. Galactic superwinds driven by compact and powerful starbursts undergo catastrophic cooling and establish a temperature distribution radically different to that predicted by adiabatic solution. The observational properties of supergalactic winds in X-rays and visible line regimes derived from our calculations are compared with the standard adiabatic model predictions.

  18. ON THE ORIGIN OF THE MOLECULAR OUTFLOWS IN IRAS 16293–2422

    Energy Technology Data Exchange (ETDEWEB)

    Girart, Josep M.; Palau, Aina; Torrelles, José M. [Institut de Ciències de l' Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5p 2, E-08193 Bellaterra, Catalonia (Spain); Estalella, Robert [Departament d' Astronomia i Meteorologia, Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès, Universitat de Barcelona, E-08028 Barcelona, Catalonia (Spain); Rao, Ramprasad, E-mail: girart@ice.cat [Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720 (United States)

    2014-01-01

    We present CO 3-2, SiO 8-7, C{sup 34}S 7-6, and 878 μm dust continuum subarcsecond angular resolution observations with the Submillimeter Array (SMA) toward the IRAS 16293–2422 (I16293) multiple low-mass protostellar system. The C{sup 34}S emission traces the 878 μm dust continuum well, and in addition clearly shows a smooth velocity gradient along the major axis of component I16293A. CO shows emission at moderate high velocities arising from two bipolar outflows, which appear to be perpendicular with respect to each other. The high sensitivity and higher angular resolution of these observations allows us to pinpoint well the origin of these two outflows at the center of component I16293A. Interestingly, the most compact outflow appears to point toward I16293B. Our data show that the previously reported monopolar blueshifted CO outflow associated with component I16293B seems to be part of the compact outflow arising from component I16293A. In addition, the SiO emission is also tracing this compact outflow: on the one hand, the SiO emission appears to have a jet-like morphology along the southern redshifted lobe; on the other hand, the SiO emission associated with the blueshifted northern lobe traces a well-defined arc on the border of component I16293B facing I16293A. The blueshifted CO lobe of the compact outflow splits into two lobes around the position of this SiO arc. All these results lead us to propose that the compact outflow from component I16293A is impacting on the circumstellar gas around component I16293B, possibly being diverged as a consequence of the interaction.

  19. FAST MOLECULAR OUTFLOWS IN LUMINOUS GALAXY MERGERS: EVIDENCE FOR QUASAR FEEDBACK FROM HERSCHEL

    Energy Technology Data Exchange (ETDEWEB)

    Veilleux, S.; Meléndez, M. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Sturm, E.; Gracia-Carpio, J.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; Genzel, R.; Tacconi, L.; De Jong, J. A. [Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstrasse 1, D-85748 Garching (Germany); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); González-Alfonso, E. [Departamento de Física y Matemáticas, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Sternberg, A.; Netzer, H. [Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv 69978 (Israel); Hailey-Dunsheath, S. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Verma, A. [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Rupke, D. S. N. [Department of Physics, Rhodes College, Memphis, TN 38112 (United States); Maiolino, R. [Cavendish Laboratory, University of Cambridge, 19 J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Teng, S. H., E-mail: veilleux@astro.umd.edu, E-mail: marcio@astro.umd.edu [Observational Cosmology Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2013-10-10

    We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel/PACS in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7 μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than –50 km s{sup –1}, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (∼145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s{sup –1}, is seen in only four objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ∼–1000 km s{sup –1} are measured in several objects, but median outflow velocities are typically ∼–200 km s{sup –1}. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large active galactic nucleus (AGN) fractions and luminosities [log (L{sub AGN}/L{sub ☉}) ≥ 11.8 ± 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  20. Accretion and Outflow Activity in Brown Dwarfs

    CERN Document Server

    Riaz, B

    2013-01-01

    An investigation of the magnetospheric accretion and outflow signatures in sub-stellar objects is a natural extension of similar studies conducted on classical T Tauri stars (CTTS), and helps understand if brown dwarfs (BDs) follow the same formation mechanism as stars. Over the past decade, evidence for accretion in very low-mass stars (VLMs) and BDs has been accumulated using various techniques, which indicates that the overall accretion characteristics are continuous across the sub-stellar boundary. Outflow activity in VLMs and BDs has been confirmed based on spectro-astrometry of forbidden emission lines observed in the optical, and in millimetre continuum images of CO J=2-1 emission. This review summarizes the past and current state of observational work on accretion and outflow activity in VLMs and BDs, particularly with the advent of new instruments such as VLT/X-Shooter which has allowed the study of several accretion and outflow indicators over a wider wavelength range.

  1. Disks, accretion and outflows of brown dwarfs

    CERN Document Server

    Joergens, V; Liu, Y; Pascucci, I; Whelan, E; Alcala, J; Biazzo, K; Costigan, G; Gully-Santiago, M; Henning, Th; Natta, A; Rigliaco, E; Rodriguez-Ledesma, V; Sicilia-Aguilar, A; Tottle, J; Wolf, S

    2012-01-01

    Characterization of the properties of young brown dwarfs are important to constraining the formation of objects at the extreme low-mass end of the IMF. While young brown dwarfs share many properties with solar-mass T Tauri stars, differences may be used as tests of how the physics of accretion/outflow and disk chemistry/dissipation depend on the mass of the central object. This article summarizes the presentations and discussions during the splinter session on 'Disks, accretion and outflows of brown dwarfs' held at the CoolStars17 conference in Barcelona in June 2012. Recent results in the field of brown dwarf disks and outflows include the determination of brown dwarf disk masses and geometries based on Herschel far-IR photometry (70-160 um), accretion properties based on X-Shooter spectra, and new outflow detections in the very low-mass regime.

  2. Electron-positron outflow from black holes

    CERN Document Server

    Van Putten, M H P M

    2000-01-01

    Gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of the central engine in GRBs is a missing link in the theory of fireballs to their stellar mass progenitors. Here it is shown that rotating black holes produce electron-positron outflow when brought into contact with a strong magnetic field. The outflow is produced by a coupling of the spin of the black hole to the orbit of the particles. For a nearly extreme Kerr black hole, particle outflow from an initial state of electrostatic equilibrium has a normalized isotropic emission of $\\sim external magnetic field strength, B_c=4.4 x 10^{13}G, and M is the mass of the black hole. This initial outflow has a half-opening angle given.

  3. Bipolar Molecular Outflows and Hot Cores in Glimpse Extended Green Objects (EGOs)

    Science.gov (United States)

    Cyganowski, C. J.; Brogan, C. L.; Hunter, T. R.; Churchwell, E.; Zhang, Q.

    2011-03-01

    We present high angular resolution Submillimeter Array and Combined Array for Research in Millimeter-wave Astronomy observations of two GLIMPSE Extended Green Objects (EGOs)—massive young stellar object (MYSO) outflow candidates identified based on their extended 4.5 μm emission in Spitzer images. The millimeter observations reveal bipolar molecular outflows, traced by high-velocity 12CO(2-1) and HCO+(1-0) emission, coincident with the 4.5 μm lobes in both sources. SiO(2-1) emission confirms that the extended 4.5 μm emission traces active outflows. A single dominant outflow is identified in each EGO, with tentative evidence for multiple flows in one source (G11.92-0.61). The outflow driving sources are compact millimeter continuum cores, which exhibit hot core spectral line emission and are associated with 6.7 GHz Class II CH3OH masers. G11.92-0.61 is associated with at least three compact cores: the outflow driving source, and two cores that are largely devoid of line emission. In contrast, G19.01-0.03 appears as a single MYSO. The difference in multiplicity, the comparative weakness of its hot core emission, and the dominance of its extended envelope of molecular gas all suggest that G19.01-0.03 may be in an earlier evolutionary stage than G11.92-0.61. Modeling of the G19.01-0.03 spectral energy distribution suggests that a central (proto)star (M ~ 10 M sun) has formed in the compact millimeter core (M gas ~12-16 M sun), and that accretion is ongoing at a rate of ~10-3 M sun year-1. Our observations confirm that these EGOs are young MYSOs driving massive bipolar molecular outflows and demonstrate that considerable chemical and evolutionary diversity are present within the EGO sample.

  4. Fueling active galactic nuclei. II. Spatially resolved molecular inflows and outflows

    Energy Technology Data Exchange (ETDEWEB)

    Davies, R. I.; Erwin, P.; Burtscher, L.; Lin, M.; Orban de Xivry, G.; Rosario, D. J.; Schnorr-Müller, A. [Max-Planck-Institute für Extraterrestrische Physik, Postfach 1312, D-85741 Garching (Germany); Maciejewski, W. [Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park, 146 Brownlow Hill, L3 5RF (United Kingdom); Hicks, E. K. S. [Astronomy Department, University of Alaska, Anchorage, Alaska 99508 (United States); Emsellem, E. [European Southern Observatory, Karl-Schwarzschild Str. 1, D-85748 Garching (Germany); Dumas, G. [Institut de Radio Astronomie Millimétrique (IRAM), 300 Rue de la Piscine, Domaine Universitaire, F-38406 Saint Martin d' Heres (France); Malkan, M. A. [Astronomy Division, University of California, Los Angeles, CA 90095-1562 (United States); Müller-Sánchez, F. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389 (United States); Tran, A. [Department of Astronomy, University of Washington Seattle, WA 98195 (United States)

    2014-09-10

    We analyze the two-dimensional distribution and kinematics of the stars as well as molecular and ionized gas in the central few hundred parsecs of five active and five matched inactive galaxies. The equivalent widths of the Brγ line indicate that there is no ongoing star formation in their nuclei, although recent (terminated) starbursts are possible in the active galaxies. The stellar velocity fields show no signs of non-circular motions, while the 1-0 S(1) H{sub 2} kinematics exhibit significant deviations from simple circular rotation. In the active galaxies the H{sub 2} kinematics reveal inflow and outflow superimposed on disk rotation. Steady-state circumnuclear inflow is seen in three active galactic nuclei (AGNs), and hydrodynamical models indicate it can be driven by a large-scale bar. In three of the five AGNs, molecular outflows are spatially resolved. The outflows are oriented such that they intersect, or have an edge close to, the disk, which may be the source of molecular gas in the outflow. The relatively low speeds imply the gas will fall back onto the disk, and with moderate outflow rates, they will have only a local impact on the host galaxy. H{sub 2} was detected in two inactive galaxies. These exhibit chaotic circumnuclear dust morphologies and have molecular structures that are counter-rotating with respect to the main gas component, which could lead to gas inflow in the near future. In our sample, all four galaxies with chaotic dust morphology in the circumnuclear region exist in moderately dense groups with 10-15 members where accretion of stripped gas can easily occur.

  5. Neutral hydrogen in galactic fountains

    CERN Document Server

    Booth, C M

    2007-01-01

    Simulations of an isolated Milky Way-like galaxy, in which supernovae power a galactic fountain, reproduce the observed velocity and 21cm brightness statistics of galactic neutral hydrogen (HI). The simulated galaxy consists of a thin HI disk, similar in extent and brightness to that observed in the Milky Way, and extra-planar neutral gas at a range of velocities due to the galactic fountain. Mock observations of the neutral gas resemble the HI flux measurements from the Leiden-Argentine-Bonn (LAB) HI, survey, including a high-velocity tail which matches well with observations of high-velocity clouds. The simulated high-velocity clouds are typically found close to the galactic disk, with a typical line-of-sight distance of 13kpc from observers on the solar circle. The fountain efficiently cycles matter from the centre of the galaxy to its outskirts at a rate of around 0.5 M_sun/yr

  6. Radiative transfer in ultra-relativistic outflows

    OpenAIRE

    Beloborodov, Andrei M.

    2010-01-01

    Analytical and numerical solutions are obtained for the equation of radiative transfer in ultra-relativistic opaque jets. The solution describes the initial trapping of radiation, its adiabatic cooling, and the transition to transparency. Two opposite regimes are examined: (1) Matter-dominated outflow. Surprisingly, radiation develops enormous anisotropy in the fluid frame before decoupling from the fluid. The radiation is strongly polarized. (2) Radiation-dominated outflow. The transfer occu...

  7. The Nuclear Outflows and Feedback in the Seyfert 2 Galaxy Markarian 573

    CERN Document Server

    Schlesinger, K; Martini, Paul; Shields, Joseph C; Fields, Dale

    2009-01-01

    We present a study of outflow and feedback in the well-known Seyfert 2 galaxy Markarian 573 using high angular resolution long-slit spectrophotometry obtained with the Hubble Space Telescope Imaging Spectrograph (STIS). Through analysis of the kinematics and ionization state of a biconical outflow region emanating from the nucleus, we find that the outflow does not significantly accelerate the surrounding host-galaxy interstellar gas and is too weak to be a strong ionization mechanism in the extended emission regions. Instead, the excitation of the extended regions is consistent with photoionization by the active nucleus. From energetics arguments we show that the nuclear outflow is slow and heavy and has a mechanical luminosity that is only ~1% of the estimated bolometric luminosity of the system. The energy in the outflow is able to mildly shape the gas in the extended regions but appears to be insufficient to unbind it, or even to plausibly disrupt star formation. These results are at odds with the picture...

  8. Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study

    NARCIS (Netherlands)

    Sahai, Raghvendra; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W.

    1994-01-01

    Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and

  9. An outflow origin of the [Ne II] emission in the T Tauri triplet

    NARCIS (Netherlands)

    van Boekel, R.; Guedel, M.; Henning, Th.; Lahuis, F.; Pantin, E.

    2009-01-01

    Context. The 12.81 mu m [Ne II] line has recently gained interest as a potential tracer of gas in the tenuous surface layers of circumstellar disks and in outflow-related shocks. Evidence has been found for a proportionality between [Ne II] emission and X-ray luminosity, supporting the hypothesis th

  10. Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study

    NARCIS (Netherlands)

    Sahai, Raghvendra; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W.

    1994-01-01

    Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and

  11. Theory of photospheric emission from relativistic outflows

    CERN Document Server

    Ruffini, R; Vereshchagin, G V

    2013-01-01

    (shortened) In this paper we reexamine the optical depth of ultrarelativistic spherically symmetric outflows and reevaluate the photospheric radius for each model during both the acceleration and coasting phases. It is shown that for both the wind and the shell models there are two asymptotic solutions for the optical depth during the coasting phase of the outflow. In particular we show that quite counterintuitively a geometrically thin shell may appear as a thick wind for photons propagating inside it. For this reason we introduce notions of photon thick and photon thin outflows, which appear more general and better physically motivated with respect to winds and shells. Photosphere of relativistic outflow is a dynamic surface. We study its geometry and find that the photosphere of photon thin outflow has always a convex shape, while in the photon thick one it is initially convex (there is always a photon thin layer in any outflow) and then it becomes concave asymptotically approaching the photosphere of an i...

  12. Chandra ACIS-S Observations of Three Quasars with Low-Redshift Damped Ly-alpha Absorption Constraints on the Cosmic Neutral-Gas-Phase Metallicity at Redshift z \\approx 0.4

    CERN Document Server

    Turnshek, D A; Ptak, A F; Griffiths, R E; Monier, E M; Turnshek, David A.; Rao, Sandhya M.; Ptak, Andrew F.; Griffiths, Richard E.; Monier, Eric M.

    2003-01-01

    Chandra X-Ray Observatory (CXO) ACIS-S spectra of three quasars which lie behind three foreground damped Lyman alpha (DLA) absorbers are analyzed in order to attempt to determine the amount of photoelectric absorption due to metals present in their x-ray spectra. These absorbers are the three largest neutral hydrogen column density absorption-line systems known at low redshift (0.313 \\le z_abs \\le 0.524). They have HI column densities which lie between 3E21 and 5E21 atoms/cm^2. At these redshifts the amount of photoelectric absorption at x-ray energies is primarily an indicator of the oxygen abundance. Since the column densities of these systems are so high, one would expect accurate metallicity measurements of them to yield a robust estimate of the column-density-weighted cosmic neutral-gas-phase metallicity at z \\approx 0.4. We consider cases where the DLA gas has solar element abundance ratios and ones with the alpha-group element abundance ratios enhanced. For the adopted assumptions, the column-density-w...

  13. IUE observations of high velocity gas towards the M16 nebula

    Science.gov (United States)

    Welsh, B. Y.

    1984-03-01

    The star HD 168183, which is part of the giant H II region-molecular cloud complex of M16 (NGC 6611), has been observed at high resolution using the IUE satellite. High velocity interstellar absorption components have been detected at velocities of -83, -38 and +40 km s-1 and it is proposed that a stellar wind-driven shock-front, interacting with the ambient neutral interstellar gas, is responsible for such complex velocity structure. Strong absorption from five of the 12C16O UV molecular lines has also been detected and the present UV absorption line data seem consistent with radio observations of M16 in which the Tenorio-Tagle 'champagne' model has been invoked to explain the ionized and neutral gas outflows from the nebula.

  14. Outflows and complex stellar kinematics in SDSS star forming galaxies

    CERN Document Server

    Cicone, Claudia; Marconi, Alessandro

    2016-01-01

    We investigate the properties of star formation-driven outflows by using a large spectroscopic sample of ~160,000 local "normal" star forming galaxies, drawn from the SDSS, spanning a wide range of star formation rates and stellar masses. The galaxy sample is divided into a fine grid of bins in the M_*-SFR parameter space, for each of which we produce a composite spectrum by stacking together the SDSS spectra of the galaxies contained in that bin. We exploit the high signal-to-noise of the stacked spectra to study the emergence of faint features of optical emission lines that may trace galactic outflows and would otherwise be too faint to detect in individual galaxy spectra. We adopt a novel approach that relies on the comparison between the line-of-sight velocity distribution (LoSVD) of the ionised gas (as traced by the [OIII]5007 and Halpha+[NII]6548,6583 emission lines) and the LoSVD of the stars, which are used as a reference tracing virial motions. Significant deviations of the gas kinematics from the st...

  15. Active Galactic Nuclei Feedback and Galactic Outflows

    Science.gov (United States)

    Sun, Ai-Lei

    Feedback from active galactic nuclei (AGN) is thought to regulate the growth of supermassive black holes (SMBHs) and galaxies. The most direct evidence of AGN feedback is probably galactic outflows. This thesis addresses the link between SMBHs and their host galaxies from four different observational perspectives. First, I study the local correlation between black hole mass and the galactic halo potential (the MBH - Vc relation) based on Very Large Array (VLA) HI observations of galaxy rotation curves. Although there is a correlation, it is no tighter than the well-studied MBH - sigma* relation between the black hole mass and the potential of the galactic bulge, indicating that physical processes, such as feedback, could link the evolution of the black hole to the baryons in the bulge. In what follows, I thus search for galactic outflows as direct evidence of AGN feedback. Second, I use the Atacama Large Millimeter Array (ALMA) to observe a luminous obscured AGN that hosts an ionized galactic outflow and find a compact but massive molecular outflow that can potentially quench the star formation in 10. 6 years.The third study extends the sample of known ionized outflows with new Magellan long-slit observations of 12 luminous obscured AGN. I find that most luminous obscured AGN (Lbol > 1046 ergs s-1) host ionized outflows on 10 kpc scales, and the size of the outflow correlates strongly with the luminosity of the AGN. Lastly, to capitalize on the power of modern photometric surveys, I experiment with a new broadband imaging technique to study the morphology of AGN emission line regions and outflows. With images from the Sloan Digital Sky Survey (SDSS), this method successfully constructs images of the [OIII]lambda5007 emission line and reveals hundreds of extended emission-line systems. When applied to current and future surveys, such as the Large Synoptic Survey Telescope (LSST), this technique could open a new parameter space for the study of AGN outflows. In

  16. A robust measurement of the mass outflow rate of the galactic outflow from NGC 6090

    Science.gov (United States)

    Chisholm, John; Tremonti Christy, A.; Leitherer, Claus; Chen, Yanmei

    2016-11-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si IV absorption lines to calculate the scaling of velocity (v), covering fraction (Cf), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: v ∝ (1 - Ri/r)β (where Ri is the inner outflow radius). We find that the velocity (β = 0.43) is consistent with an outflow driven by an r-2 force with the outflow radially accelerated, while the scaling of the covering fraction (Cf ∝ r-0.82) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of four weak metal lines and CLOUDY photoionization models to determine the outflow metallicity, the ionization correction, and the initial density of the outflow. Combining these values with the profile fitting, we find Ri = 63 pc, with most of the mass within 300 pc of the starburst. Finally, we find that the maximum mass outflow rate is 2.3 M⊙ yr-1 and the mass-loading factor (outflow divided by the star formation rate) is 0.09, a factor of 10 lower than the value calculated using common assumptions for the geometry, metallicity, and ionization structure of the outflow.

  17. Spitzer spectral line mapping of the HH211 outflow

    DEFF Research Database (Denmark)

    Dionatos, Odyssefs; Nisini, Brunella; Cabrit, Sylvie;

    2010-01-01

    Aims: We employ archival Spitzer slit-scan observations of the HH211 outflow in order to investigate its warm gas content, assess the jet mass flux in the form of H2 and probe for the existence of an embedded atomic jet. Methods: Detected molecular and atomic lines are interpreted by means......-structure lines of S, Fe+, and Si+. H2 is detected down to 5" from the source and is characterized by a "cool" T~300K and a "warm" T~1000 K component, with an extinction Av ~ 8 mag. The amount of cool H2 towards the jet agrees with that estimated from CO assuming fully molecular gas. The warm component is well...

  18. CO2-neutral fuels

    Science.gov (United States)

    Goede, A. P. H.

    2015-08-01

    The need for storage of renewable energy (RE) generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G) scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel cycle is

  19. CO2-neutral fuels

    Directory of Open Access Journals (Sweden)

    Goede A. P. H.

    2015-01-01

    Full Text Available The need for storage of renewable energy (RE generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel

  20. Ion-neutral gas reactions in a collision/reaction cell in inductively coupled plasma mass spectrometry: Correlation of ion signal decrease to kinetic rate constants

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Patrick J. [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States); Department of Chemistry, The Ohio State University, 120 18th Avenue, Columbus, OH 43210 (United States); Olesik, John W., E-mail: olesik.2@osu.edu [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States)

    2015-03-01

    Reaction gas flow rate dependent Ar{sub 2}{sup +} and Ar{sup +} signals are correlated to fundamental kinetic rate coefficients. A simple calculation, assuming that gas exits the reaction cell due only to effusion, is described to estimate the gas pressure in the reaction cell. The value of the product of the kinetic rate constant and the ion residence time in the reaction cell can be determined from experimental measurement of the decrease in an ion signal as a function of reaction gas flow rate. New kinetic rate constants are determined for the reaction of CH{sub 3}F with Ar{sup +} and Ar{sub 2}{sup +}. - Highlights: • How to determine pressure and the product of the kinetic rate constant times the ion residence time in reaction cell • Relate measured ICP-DRC-MS signals versus gas flow rate to kinetic rate constants measured previously using SIFT-MS • Describe how to determine previously unmeasured kinetic rate constants using ICP-DRC-MS.

  1. Neutral hydrogen in galaxy halos at the peak of the cosmic star formation history

    CERN Document Server

    Faucher-Giguere, C -A; Keres, D; Muratov, A L; Quataert, E; Murray, N

    2014-01-01

    Gas inflows and outflows regulate star formation in galaxies. Probing these processes is one of the central motivations for spectroscopic measurements of the circum-galactic medium. We use high-resolution cosmological zoom-in simulations from the FIRE project to make predictions for the covering fractions of neutral hydrogen around galaxies at z=2-4. These simulations resolve the interstellar medium of galaxies and explicitly implement a comprehensive set of stellar feedback mechanisms. Our simulation sample consists of 16 main halos covering the mass range M_h~2x10^9-8x10^12 Msun at z=2, including 12 halos in the mass range M_h~10^11-10^12 Msun corresponding to Lyman break galaxies (LBGs). We process our simulations with a ray tracing method to compute the ionization state of the gas. Galactic winds increase the HI covering fractions in galaxy halos by direct ejection of cool gas from galaxies and through interactions with gas inflowing from the intergalactic medium. Our simulations predict HI covering fract...

  2. Pressurized groundwater outflow experiments and numerical modeling for outflow channels on Mars

    NARCIS (Netherlands)

    Marra, Wouter A.; Hauber, Ernst; McLelland, Stuart J.; Murphy, Brendan J.; Parsons, Daniel R.; Conway, Susan J.; Roda, Manuel; Govers, Rob; Kleinhans, Maarten G.

    2014-01-01

    The landscape of Mars shows incised channels that often appear abruptly in the landscape, suggesting a groundwater source. However, groundwater outflow processes are unable to explain the reconstructed peak discharges of the largest outflow channels based on their morphology. Therefore, there is a d

  3. Reactive formulations for a neutralization of toxic industrial chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Mark D. (Albuqueruqe, NM); Betty, Rita G. (Rio Rancho, NM)

    2006-10-24

    Decontamination formulations for neutralization of toxic industrial chemicals, and methods of making and using same. The formulations are effective for neutralizing malathion, hydrogen cyanide, sodium cyanide, butyl isocyanate, carbon disulfide, phosgene gas, capsaicin in commercial pepper spray, chlorine gas, anhydrous ammonia gas; and may be effective at neutralizing hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene oxide, methyl bromide, boron trichloride, fluorine, tetraethyl pyrophosphate, phosphorous trichloride, arsine, and tungsten hexafluoride.

  4. Protostellar Outflows and Radiative Feedback from Massive Stars. II. Feedback, Star Formation Efficiency, and Outflow Broadening

    CERN Document Server

    Kuiper, Rolf; Yorke, Harold W

    2016-01-01

    We perform two-dimensional axially symmetric radiation-hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, the ratio of ejection to accretion rates, and the strength of the wide angle disk wind component. The star formation efficiency, i.e. the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects: First, the protostar grows slower with a lower luminosity at any given time, lowering radiative feedback. Second, bipolar cavities cleared by the outflow are larger, further diminishing radiative feedback on disk and core scales. Third, the higher momentum outflow sweeps up more material from the collapsing envelope, decreasing the protostar's potential mass reservoir via entrainment. The star formation efficiency varies with the ratio of ejection to accretion rates from 50% in the case of very we...

  5. Spectral-line Survey at Millimeter and Submillimeter Wavelengths toward an Outflow-shocked Region, OMC 2-FIR 4

    Science.gov (United States)

    Shimajiri, Yoshito; Sakai, Takeshi; Kitamura, Yoshimi; Tsukagoshi, Takashi; Saito, Masao; Nakamura, Fumitaka; Momose, Munetake; Takakuwa, Shigehisa; Yamaguchi, Takahiro; Sakai, Nami; Yamamoto, Satoshi; Kawabe, Ryohei

    2015-12-01

    We performed the first spectral line survey at 82-106 GHz and 335-355 GHz toward the outflow-shocked region OMC 2-FIR 4, the outflow driving source FIR 3, and the northern outflow lobe FIR 3N. We detected 120 lines of 20 molecular species. The line profiles can be classified into two types: one type is a single Gaussian component with a narrow (3 km s-1) widths. The narrow components for most of the lines are detected at all positions, suggesting that they trace the ambient dense gas. For CO, CS, HCN, and HCO+, the wide components are detected at all positions, suggesting an outflow origin. The wide components of C34S, SO, SiO, H13CN, HC15N, {{{H}}}213CO, H2CS, HC3N, and CH3OH are only detected at FIR 4, suggesting an origin as outflow-shocked gas. The rotation diagram analysis revealed that the narrow components of C2H and H13CO+ show low temperatures of 12.5 ± 1.4 K, while the wide components show high temperatures of 20-70 K. This supports our interpretation that the wide components trace the outflow and/or outflow-shocked gas. We compared the observed molecular abundances relative to H13CO+ with those of the outflow-shocked region L 1157 B1 and the hot corino IRAS 16293-2422. Although we cannot exclude the possibility that the chemical enrichment in FIR 4 is caused by hot-core chemistry, the chemical compositions in FIR 4 are more similar to those in L 1157 B1 than those in IRAS 16293-2422.

  6. Cerebral venous outflow and cerebrospinal fluid dynamics

    Directory of Open Access Journals (Sweden)

    Clive B. Beggs

    2014-12-01

    Full Text Available In this review, the impact of restricted cerebral venous outflow on the biomechanics of the intracranial fluid system is investigated. The cerebral venous drainage system is often viewed simply as a series of collecting vessels channeling blood back to the heart. However there is growing evidence that it plays an important role in regulating the intracranial fluid system. In particular, there appears to be a link between increased cerebrospinal fluid (CSF pulsatility in the Aqueduct of Sylvius and constricted venous outflow. Constricted venous outflow also appears to inhibit absorption of CSF into the superior sagittal sinus. The compliance of the cortical bridging veins appears to be critical to the behaviour of the intracranial fluid system, with abnormalities at this location implicated in normal pressure hydrocephalus. The compliance associated with these vessels appears to be functional in nature and dependent on the free egress of blood out of the cranium via the extracranial venous drainage pathways. Because constricted venous outflow appears to be linked with increased aqueductal CSF pulsatility, it suggests that inhibited venous blood outflow may be altering the compliance of the cortical bridging veins.

  7. Evolution of Mass Outflow in Protostars

    CERN Document Server

    Watson, Dan M; Fischer, William J; Forrest, W J; Manoj, P; Megeath, S Thomas; Melnick, Gary J; Najita, Joan; Neufeld, David A; Sheehan, Patrick D; Stutz, Amelia M; Tobin, John J

    2015-01-01

    We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si II], [Fe II] and [S I] line emission, and 11 of these in far-infrared [O I] emission. We use the results to derive their mass outflow rates. Thereby we observe a strong correlation of mass outflow rates with bolometric luminosity, and with the inferred mass accretion rates of the central objects, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass-flow rates, the different classes of young stellar objects lie in the sequence Class 0 -- Class I/flat-spectrum -- Class II, indicating that the trend is an evolutionary sequence in which mass outflow and accretion rates decrease together with increasing age, while maintaining rough proportionality. The survey results include two which are key tests of magnetocentrifugal outflow-acceleration mechanisms: the distribution of the outflow/accretion branching ratio b, and limits on the distribution of...

  8. Collimated Jet Or Expanding Outflow: Possible Origins of GRBs And X-Ray Flashes

    Energy Technology Data Exchange (ETDEWEB)

    Mizuta, Akira; /Kyoto U., Yukawa Inst., Kyoto /Garching, Max Planck Inst.; Yamasaki, Tatsuya; /Kyoto U., Yukawa Inst., Kyoto; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst.,; Mineshige, Shin; /Kyoto U., Yukawa Inst., Kyoto

    2006-08-10

    We investigate the dynamics of an injected outflow propagating in a progenitor in the context of the collapsar model for gamma-ray bursts (GRBs) through two dimensional axisymmetric relativistic hydrodynamic simulations. Initially, we locally inject an outflow near the center of a progenitor. We calculate 25 models, in total, by fixing its total input energy to be 10{sup 51} ergs s{sup -1} and radius of the injected outflow to be 7 x 10{sup 7} cm while varying its bulk Lorentz factor, {Lambda}{sub 0} = 1.05 {approx} 5, and its specific internal energy, {epsilon}{sub 0}/c{sup 2} 30 (with c being speed of light). The injected outflow propagates in the progenitor and drives a large-scale outflow or jet. We find a smooth but dramatic transition from a collimated jet to an expanding outflow among calculated models. The opening angle of the outflow ({theta}{sub sim}) is sensitive to {Lambda}{sub 0}; we find {theta}{sub sim} < 2{sup o} for {Lambda}{sub 0} {approx}> 3. The maximum Lorentz factor is, on the other hand, sensitive to both of {Lambda}{sub 0} and {epsilon}{sub 0}; roughly {Lambda}{sub max} {approx} {Lambda}{sub 0}(1 + {epsilon}{sub 0}/c{sup 2}). In particular, a very high Lorentz factor of {Lambda}{sub max} {approx}> 100 is achieved in one model. A variety of opening angles can arise by changing {epsilon}{sub 0}, even when the maximum Lorentz factor is fixed. The jet structure totally depends on {Lambda}{sub 0}. When {Lambda}{sub 0} is high, a strong bow shock appears and generates a back flow. High pressure progenitor gas heated by the bow shock collimates the outflow to form a narrow, relativistic jet. A number of internal oblique shocks within the jet are generated by the presence of the back flow and/or shear instability. When {Lambda}{sub 0} is low, on the contrary, the outflow expands soon after the injection, since the bow shock is weak and thus the pressure of the progenitor gas is not high enough to confine the flow. Our finding will explain a smooth

  9. Neutral interstellar helium parameters based on Ulysses/GAS and IBEX-Lo observations: what are the reasons for the differences?

    CERN Document Server

    Katushkina, Olga A; Wood, Brain E; McMulin, Donald R

    2014-01-01

    Recent analysis of the interstellar helium fluxes measured in 2009-2010 at Earth orbit by the Interstellar Boundary Explorer (IBEX) has suggested that the interstellar velocity (both direction and magnitude) is inconsistent with that derived previously from Ulysses/GAS observations made in the period from 1990 to 2002 at 1.5-5.5 AU from the Sun. Both results are model-dependent and models that were used in the analyses are different. In this paper, we perform an analysis of the Uysses/GAS and IBEX-Lo data using our state-of-the-art 3D time-dependent kinetic model of interstellar atoms in the heliosphere. For the first time we analyze Ulysses/GAS data from year 2007, the closest available Ulysses/GAS observations in time to the IBEX observations. We show that the interstellar velocity derived from the Ulysses 2007 data is consistent with previous Ulysses results and does not agree with the velocity derived from IBEX. This conclusion is very robust since, as is shown in the paper, it does not depend on the ioni...

  10. What is Neutrality?

    NARCIS (Netherlands)

    Pierik, R.; van der Burg, W.

    2014-01-01

    This paper reinvestigates the question of liberal neutrality. We contend that current liberal discussions have been dominated - if not hijacked - by one particular interpretation of what neutrality could imply, namely, exclusive neutrality, that aims to exclude religious and cultural expressions

  11. INTEGRAL FIELD SPECTROSCOPY OF AGN ABSORPTION OUTFLOWS: MRK 509 AND IRAS F04250–5718

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guilin; Arav, Nahum [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Rupke, David S. N., E-mail: glliu@vt.edu [Department of Physics, Rhodes College, Memphis, TN 38112 (United States)

    2015-11-15

    Ultraviolet (UV) absorption lines provide abundant spectroscopic information enabling the probe of the physical conditions in active galactic nucleus (AGN) outflows, but the outflow radii (and the energetics consequently) can only be determined indirectly. We present the first direct test of these determinations using integral field unit (IFU) spectroscopy. We have conducted Gemini IFU mapping of the ionized gas nebulae surrounding two AGNs, whose outflow radii have been constrained by UV absorption line analyses. In Mrk 509, we find a quasi-spherical outflow with a radius of 1.2 kpc and a velocity of ∼290 km s{sup −1}, while IRAS F04250–5718 is driving a biconical outflow extending out to 2.9 kpc, with a velocity of ∼580 km s{sup −1} and an opening angle of ∼70°. The derived mass flow rate ∼5 and >1 M{sub ⊙} yr{sup −1}, respectively, and the kinetic luminosity ≳1 × 10{sup 41} erg s{sup −1} for both. Adopting the outflow radii and geometric parameters measured from IFU, absorption line analyses would yield mass flow rates and kinetic luminosities in agreement with the above results within a factor of ∼2. We conclude that the spatial locations, kinematics, and energetics revealed by this IFU emission-line study are consistent with pre-existing UV absorption line analyses, providing a long-awaited direct confirmation of the latter as an effective approach for characterizing outflow properties.

  12. On the X-ray low- and high-velocity outflows in AGNs

    CERN Document Server

    Ramirez, J M

    2011-01-01

    An exploration of the relationship between bolometric luminosity and outflow velocity, for two classes of X-ray outflows in a large sample of active galactic nuclei has been performed. We find that line radiation pressure could be one physical mechanism that might accelerate the gas we observe in warm absorber, v~100-1000 km/s, and on comparable but less stringent grounds the ultra-fast outflows (UFOs), v~0.03-0.3c. If comparable with the escape velocity of the system; the first is naturally located at distances of the dusty torus, ~ 1 pc, and the second at sub-parsec scales, ~ 0.01 pc, in accordance with large set of observational evidence existing in the literature. The presentation of this relationship might give us key clues for our understanding of the different physical mechanisms acting in the center of galaxies, the feedback process and its impact on the evolution of the host galaxy.

  13. Observations of Molecular Outflow in Car 291.6-01.9

    Science.gov (United States)

    Saul, M.; Saul, L.

    2012-01-01

    We report the first observations of a dense molecular gas nebula and bipolar outflow in Car 291.6-01.9, showing characteristics of an embedded young stellar object (YSO). Using the Mopra radio telescope near Coonabarabaran, Australia, we image the kinematic structure of several emission features to examine physical properties within a molecular clump of mass ~3.2 ± 0.6 × 103 M ⊙ in which a stellar cluster may be forming. Motivated by acquiring a more thorough understanding of star formation we ask what may have initiated collapse in the clump; observed outflow alignment is suggestive of ~1.0 pc distant massive star HD 308280 radiative-driven compression as a formation trigger for the dense core. An outflow derived age of <106 years, together with significant C18O and SO core depletion, support the case for the core as the host of an extremely YSO cluster.

  14. A systematic study of Lyman-Alpha transfer through outflowing shells: Model parameter estimation

    CERN Document Server

    Gronke, Max; Dijkstra, Mark

    2015-01-01

    Outflows promote the escape of Lyman-$\\alpha$ (Ly$\\alpha$) photons from dusty interstellar media. The process of radiative transfer through interstellar outflows is often modelled by a spherically symmetric, geometrically thin shell of gas that scatters photons emitted by a central Ly$\\alpha$ source. Despite its simplified geometry, this `shell model' has been surprisingly successful at reproducing observed Ly$\\alpha$ line shapes. In this paper we perform automated line fitting on a set of noisy simulated shell model spectra, in order to determine whether degeneracies exist between the different shell model parameters. While there are some significant degeneracies, we find that most parameters are accurately recovered, especially the HI column density ($N_{\\rm HI}$) and outflow velocity ($v_{\\rm exp}$). This work represents an important first step in determining how the shell model parameters relate to the actual physical properties of Ly$\\alpha$ sources. To aid further exploration of the parameter space, we ...

  15. Observations of Protostellar Outflow Feedback in Clustered Star Formation

    CERN Document Server

    Nakamura, Fumitaka

    2015-01-01

    We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects significantly the clump dynamics. On the other hand, for clumps with masses larger than about 200 M$_\\odot$, the outflow kinetic energy is significantly smaller than the clump gravitational energy. Since the majority of stars form in such clumps, we conclude that outflow feedback cannot destroy the whole parent clump. These characteristics of the outflow feedback support the scenario of slow star formation.

  16. Magnetospheric outflows in young stellar objects

    Directory of Open Access Journals (Sweden)

    Zanni Claudio

    2014-01-01

    Full Text Available Different classes of outflows are associated with the magnetospheric activity of accreting T Tauri protostars. Stellar winds are accelerated along the open field lines anchored in the stellar surface; disk winds (extended or X-type can be launched along the open magnetic surfaces threading the accretion disk; another type of ejection can arise from the region of interaction of the closed magnetosphere with the accretion disk (magnetospheric ejections, conical winds, where the magnetic surfaces undergo quasiperiodic episodes of inflation and reconnection. In this chapter I will present the main dynamical properties of these different types of outflow. Two main issues will be addressed. First, I will try to understand if these ejection phenomena can account for the origin of the jets often observed in young forming stellar systems. Second, I will evaluate the impact of these outflows on the angular momentum evolution of the central protostar.

  17. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    Science.gov (United States)

    Wang, Tinggui; Ferland, Gary J.; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-06-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe ii UV arising from transitions to ground/low excitation levels, and very weak Fe ii at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C iv, Al iii and Mg ii but sometimes, a lack of non-resonant lines such as C iii], S iii and He ii. We interpret the Fe ii lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 Å produces Fe ii emission very similar to that observed. The gas is too cool to collisionally excite Fe ii lines, accounting for the lack of optical emission. The spectral energy distribution from the UV to the mid-infrared can be modeled as emission from a clumpy dusty torus, with UV emission being reflected/scattered light either by the dusty torus or the outflow. Within this scenario, we estimate a minimum covering factor of the outflows from a few to 20% for the Fe ii scattering region, suggesting that Fe ii BAL quasars are at a special stage of quasar evolution.

  18. Quenching the X-ray spectrum of hot halos with AGN outflows and turbulence

    Science.gov (United States)

    Gaspari, M.

    2016-06-01

    I highlight recent advancements in the astrophysics of AGN outflow feedback and diffuse hot gas. Thanks to XMM RGS resolution, we know that the X-ray cores of clusters, groups, and massive galaxies have a strong deficit of soft X-ray emission compared with the classic cooling flow prediction: dL_{x}/dT ∝ (T/T_{hot})^{2±1}. Using 3D hydrodynamic simulations, I show that such deficit arises from the tight self-regulation between thermal instability condensation and AGN outflow feedback. Multiphase filaments condense out of the hot plasma, they rain onto the central SMBH, and boost the AGN outflows via chaotic cold accretion. The sub-relativistic outflows thermalize in the core via shocks and turbulence, releasing more heat in the inner cooler phase, thus inducing the observed soft X-ray decline. I discuss how we can leverage XMM capabilities in the next decade by probing turbulence, conduction, AGN accretion and outflows via the information contained in X-ray spectra and surface brightness. I focus on the importance of selecting a few objects with Ms exposure and how we can unveil multiphase halos through the synergy between simulations and multiwavelength observations.

  19. Unravelling the complex structure of AGN-driven outflows: II. Photoionization and energetics

    CERN Document Server

    Karouzos, Marios; Bae, Hyun-Jin

    2016-01-01

    Outflows have been shown to be prevalent in galaxies hosting luminous active galactic nuclei (AGNs) and present a physically plausible way to couple the AGN energy output with the interstellar medium of their hosts. Despite their prevalence, accurate characterization of these outflows has been challenging. In the second of a series of papers, we use Gemini Multi-Object Spectrograph IFU data of 6 local (z<0.1) and moderate-luminosity Type 2 AGNs to study the ionization properties and energetics of AGN-driven outflows. We find strong evidence that connect the extreme kinematics of the ionized gas with the AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as virial motions or rotation, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that from 30% up to 90% of the total mass and kinetic energy of the outflow is contained within the central kpc of the galaxy. The spatially i...

  20. Active galaxies. A fast and long-lived outflow from the supermassive black hole in NGC 5548.

    Science.gov (United States)

    Kaastra, J S; Kriss, G A; Cappi, M; Mehdipour, M; Petrucci, P-O; Steenbrugge, K C; Arav, N; Behar, E; Bianchi, S; Boissay, R; Branduardi-Raymont, G; Chamberlain, C; Costantini, E; Ely, J C; Ebrero, J; Di Gesu, L; Harrison, F A; Kaspi, S; Malzac, J; De Marco, B; Matt, G; Nandra, K; Paltani, S; Person, R; Peterson, B M; Pinto, C; Ponti, G; Pozo Nuñez, F; De Rosa, A; Seta, H; Ursini, F; de Vries, C P; Walton, D J; Whewell, M

    2014-07-01

    Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution x-ray and ultraviolet (UV) observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas not seen before. It blocks 90% of the soft x-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and, at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.

  1. Outflows Driven by Quasars in High-Redshift Galaxies with Radiation Hydrodynamics

    Science.gov (United States)

    Bieri, Rebekka; Dubois, Yohan; Rosdahl, Joakim; Wagner, Alexander; Silk, Joseph; Mamon, Gary A.

    2016-09-01

    The quasar mode of Active Galactic Nuclei (AGN) in the high-redshift Universe is routinely observed in gas-rich galaxies together with large-scale AGN-driven winds. It is crucial to understand how photons emitted by the central AGN source couple to the ambient interstellar-medium to trigger large-scale outflows. By means of radiation-hydrodynamical simulations of idealised galactic discs, we study the coupling of photons with the multiphase galactic gas, and how it varies with gas cloud sizes, and the radiation bands included in the simulations, which are ultraviolet (UV), optical, and infrared (IR). We show how a quasar with a luminosity of 146 erg s-1 can drive large-scale winds with velocities of 102 - 103 km s-1 and mass outflow rates around 10^3 M_⊙ yr^{-1} for times of order a few million years. Infrared radiation is necessary to efficiently transfer momentum to the gas via multi-scattering on dust in dense clouds. However, IR multi-scattering, despite being extremely important at early times, quickly declines as the central gas cloud expands and breaks up, allowing the radiation to escape through low gas density channels. The typical number of multi-scattering events for an IR photon is only about a quarter of the mean optical depth from the center of the cloud. Our models account for the observed outflow rates of ˜ 500-1000 M_{⊙} {yr}^{-1} and high velocities of ˜ 10^3 km s^{-1}, favouring winds that are energy-driven via extremely fast nuclear outflows, interpreted here as being IR-radiatively-driven winds.

  2. Quenching of Star Formation in Molecular Outflow Host NGC 1266

    CERN Document Server

    Alatalo, K; Graves, G; Deustua, S; Young, L M; Davis, T A; Bureau, M; Bayet, E; Blitz, L; Bois, M; Bournaud, F; Cappellari, M; Davies, R L; de Zeeuw, P T; Emsellem, E; Khochfar, S; Krajnovic, D; Kuntschner, H; McDermid, R M; Morganti, R; Naab, T; Oosterloo, T; Sarzi, M; Scott, N; Serra, P; Weijmans, A

    2012-01-01

    We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a role in instigating outflows in other systems, deep imaging of NGC 1266 as well as stellar kinematic observations from SAURON, have failed to provide evidence that NGC 1266 has recently been involved in a major interaction. The molecular gas and the instantaneous SF tracers indicate that the current sites of star formation are located in a hypercompact disk within 200 pc of the nucleus (Fig. 1; SF rate ~ 2 Msuns/yr). On the other hand, tracers of recent star formation, such as the H{\\beta} absorption map from SAURON and stellar population analysis show that the young stars are distributed throughout a larger area of the galaxy than current star formation. As the AGN at the center of NGC 1266 continues to drive cold...

  3. A Two-Temperature Model of Magnetized Protostellar Outflows

    CERN Document Server

    Wang, Liang-Yao; Krasnopolsky, Ruben; Chiang, Tzu-Yang

    2015-01-01

    We explore kinematics and morphologies of molecular outflows driven by young protostars using magnetohydrodynamic simulations in the context of the unified wind model of Shang et al. The model explains the observed high-velocity jet and low-velocity shell features. In this work we investigate how these characteristics are affected by the underlying temperature and magnetic field strength. We study the problem of a warm wind running into a cold ambient toroid by using a tracer field that keeps track of the wind material. While an isothermal equation of state is adopted, the effective temperature is determined locally based on the wind mass fraction. In the unified wind model, the density of the wind is cylindrically stratified and highly concentrated toward the outflow axis. Our simulations show that for a sufficiently magnetized wind, the jet identity can be well maintained even at high temperatures. However, for a high temperature wind with low magnetization, the thermal pressure of the wind gas can drive ma...

  4. An Origin for Multi-Phase Gas in Galactic Winds and Halos

    CERN Document Server

    Thompson, Todd A; Zhang, Dong; Weinberg, David

    2016-01-01

    The origin of high velocity cool gas seen in galactic winds remains unknown. Following Wang (1995), we argue that rapid radiative cooling in initially hot (10^7-10^8 K) thermally-driven outflows can produce fast neutral atomic and photoionized cool gas. Outflows with hot gas mass-loading factor relative to star formation rate of beta > 0.5 cool on scales ranging from the size of the host to tens of kpc. We provide scalings for the cooling radius r_cool, density, column density, emission measure, radiative efficiency, and cool gas velocity. At r_cool, the gas produces X-ray and then UV/optical line emission at velocities of hundreds to thousands of km/s with a total power bounded from above by the energy injection rate 0.01 L_star if the flow is powered by steady-state star formation with luminosity L_star. The wind is thermally and convectively unstable at and beyond r_cool. Thermal instability can amplify density fluctuations by a factor of ~100, potentially leading to a multi-phase medium. Cooled winds can ...

  5. Gemini GMOS and WHT SAURON integral-field spectrograph observations of the AGN driven outflow in NGC 1266

    CERN Document Server

    Davis, Timothy A; McDermid, Richard M; Bureau, Martin; Sarzi, Marc; Nyland, Kristina; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frederic; Cappellari, Michele; Crocker, Alison; Davies, Roger L; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M

    2012-01-01

    We use the SAURON and GMOS integral field spectrographs to observe the active galactic nucleus (AGN) powered outflow in NGC 1266. This unusual galaxy is relatively nearby (D=30 Mpc), allowing us to investigate the process of AGN feedback in action. We present maps of the kinematics and line strengths of the ionised gas emission lines Halpha, Hbeta, [OIII], [OI], [NII] and [SII], and report on the detection of Sodium D absorption. We use these tracers to explore the structure of the source, derive the ionised and atomic gas kinematics and investigate the gas excitation and physical conditions. NGC 1266 contains two ionised gas components along most lines of sight, tracing the ongoing outflow and a component closer to the galaxy systemic, the origin of which is unclear. This gas appears to be disturbed by a nascent AGN jet. We confirm that the outflow in NGC 1266 is truly multiphase, containing radio plasma, atomic, molecular and ionised gas and X-ray emitting plasma. The outflow has velocities up to \\pm900 km/...

  6. Electronic properties of GaSe, InSe, GaS and GaTe layered semiconductors: charge neutrality level and interface barrier heights

    Science.gov (United States)

    Brudnyi, V. N.; Sarkisov, S. Yu; Kosobutsky, A. V.

    2015-11-01

    Density functional theory calculations have been applied to study the structural and electronic properties of layered ɛ-GaSe, γ-InSe, β-GaS and GaTe compounds. The optimized lattice parameters have been obtained using vdW-DF2-C09 exchange-correlation functional, which is able to describe dispersion forces and produces interlayer distances in close agreement with experiments. Based on the calculated electronic band structures, the energy position of the charge neutrality level (CNL) in the III-VI semiconductors has been estimated for the first time. The room-temperature values of CNL are found to be 0.80 eV, 1.02 eV, 0.72 eV and 0.77 eV for ɛ-GaSe, β-GaS, GaTe and γ-InSe, respectively. The persistent p-type conductivity of the intentionally undoped ɛ-GaSe, β-GaS and GaTe and n-type conductivity of γ-InSe crystals are discussed and explained using the concept of CNL. We also estimated the barrier heights for a number of metal/semiconductor and semiconductor/semiconductor interfaces assuming partial Fermi level pinning at the CNL. A reasonable agreement between our calculations and the available experimental data has been obtained.

  7. Relativistic hadrons and the origin of relativistic outflows in active galactic nuclei

    Science.gov (United States)

    Contopoulos, John; Kazanas, D.

    1995-01-01

    We examine the hydrodynamic origin of relativistic outflows in active galactic nuclei (AGN). Specifically, we propose that the presence of a population of relativistic hadrons in the AGN 'central engine' and the associated neutron production suffices to produce outflows which under rather general conditions could be relativistic. The main such condition is that the size of the neutron production region be larger than the neutron flight path tau(sub n) approximately 3 x 10(exp 13) cm. This condition guarantees that the mean energy per particle in the proton fluid, resulting from the decay of the neutrons outside their production region, be greater than the proton rest mass. The expansion of this fluid can then lead naturally to a relativistic outflow by conversion of its internal energy to directed motion. We follow the development of such flows by solving the mass, energy as well as the kinetic equation for the proton gas in steady state, taking into account the source terms due to compute accurately the adiabatic index of the expanding gas, and in conjunction with Bernoulli's equation the detailed evolution of the bulk Lorentz factor. We further examine the role of large-scale magnetic fields in confining these outflows to produce the jets observed at larger scales.

  8. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    CERN Document Server

    Wang, Tinggui; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-01-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe II UV arising from transitions to ground/low excitation levels, and very weak Fe II at wavelengths longer than 2800 {\\AA}. The spectra of these quasars display strong resonant emission lines, such as C IV, Al III and Mg II but sometimes, a lack of non-resonant lines such as C III], S III and He II. We interpret the Fe II lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 {\\AA} produces Fe II emission very similar to that observed. The gas is too cool to coll...

  9. Water distribution in shocked regions of the NGC1333-IRAS4A protostellar outflow

    CERN Document Server

    Santangelo, G; Codella, C; Lorenzani, A; Yildiz, U A; Antoniucci, S; Bjerkeli, P; Cabrit, S; Giannini, T; Kristensen, L; Liseau, R; Mottram, J C; Tafalla, M; van Dishoeck, E F

    2014-01-01

    We present the study of the H2O spatial distribution at two bright shocked regions along IRAS4A, one of the strongest H2O emitters among the Class 0 outflows. We obtained Herschel-PACS maps of the IRAS4A outflow and HIFI observations of two shocked positions. The largest HIFI beam of 38 arcsec at 557 GHz was mapped in several key water lines with different upper energy levels, to reveal possible spatial variations of the line profiles. We detect four H2O lines and CO (16-15) at the two selected positions. In addition, transitions from related outflow and envelope tracers are detected. Different gas components associated with the shock are identified in the H2O emission. In particular, at the head of the red lobe of the outflow, two distinct gas components with different excitation conditions are distinguished in the HIFI emission maps: a compact component, detected in the ground-state water lines, and a more extended one. Assuming that these two components correspond to two different temperature components ob...

  10. Protostellar Outflow Evolution in Turbulent Environments

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, A; Frank, A; Carroll, J; Blackman, E; Quillen, A

    2008-04-11

    The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.

  11. Accretion, Outflows, and Winds of Magnetized Stars

    CERN Document Server

    Romanova, M M

    2016-01-01

    Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars...

  12. The Resolved Outflow from 3C 48

    Science.gov (United States)

    Shih, Hsin-Yi; Stockton, Alan

    2014-10-01

    We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the

  13. Radiation pressure confinement - III. The origin of the broad ionization distribution in AGN outflows

    Science.gov (United States)

    Stern, Jonathan; Behar, Ehud; Laor, Ari; Baskin, Alexei; Holczer, Tomer

    2014-12-01

    The winds of ionized gas driven by active galactic nuclei (AGN) can be studied through absorption lines in their X-ray spectra. A recurring feature of these outflows is their broad ionization distribution, including essentially all ionization levels (e.g., Fe0+ to Fe25+). This characteristic feature can be quantified with the absorption measure distribution (AMD), defined as the distribution of column density with ionization parameter |dN/d log ξ|. Observed AMDs extend over 0.1 ≲ ξ ≲ 104 (cgs), and are remarkably similar in different objects. Power-law fits (|dN/d log ξ| ≈ N1ξa) yield N1 = 3 × 1021 cm- 2 ± 0.4 dex and a = 0-0.4. What is the source of this broad ionization distribution, and what sets the small range of observed N1 and a? A common interpretation is a multiphase outflow, with a wide range of gas densities in a uniform gas pressure medium. However, the incident radiation pressure leads to a gas pressure gradient in the photoionized gas, and therefore to a broad range of ionization states within a single slab. We show that this compression of the gas by the radiation pressure leads to an AMD with |dN/d log ξ| = 8 × 1021 ξ0.03 cm-2, remarkably similar to that observed. The calculated values of N1 and a depend weakly on the gas metallicity, the ionizing spectral slope, the distance from the nucleus, the ambient density, and the total absorber column. Thus, radiation pressure compression (RPC) of the photoionized gas provides a natural explanation for the observed AMD. RPC predicts that the gas pressure increases with decreasing ionization, which can be used to test the validity of RPC in ionized AGN outflows.

  14. Outflow Entrainment and Feedback: A Case Study with HH46/47 Molecular Outflow

    Science.gov (United States)

    Zhang, Yichen; Arce, H.; Mardones, D.; Cabrit, S.

    2017-06-01

    Our ALMA multi-cycle multi-band observations of HH46/47 outflow show co-existence of entrainment by both wide-angle wind and jet bow-shock and this outflow is at a moment that the former has just become dominant. The estimated outflow mass and strength suggest that it has already strongly affected the core-to-star efficiency to 1/3 at this early stage. The zoom-in observation also reveals multiple wide outflowing shells with positions and shapes smoothly changing over a wide range of velocity, which may be an evidence of episodic eruption not only in jet but also in the wide-angle wind.

  15. An Experimental Field Dataset with Buoyant, Neutral, and Dense Gas Atmospheric Releases and Model Comparisons in Low-Wind Speed (Diffusion) Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Veronica E. Wannberg, Gustavious Williams, Patrick Sawyer, and Richard Venedam

    2010-09-01

    Aunique field dataset from a series of low–wind speed experiments, modeling efforts using three commonly used models to replicate these releases, and statistical analysis of how well these models were able to predict the plume concentrations is presented. The experiment was designed to generate a dataset to describe the behavior of gaseous plumes under low-wind conditions and the ability of current, commonly used models to predict these movements. The dataset documents the release and transport of three gases: ammonia (buoyant), ethylene (neutral), and propylene (dense) in low–wind speed (diffusion) conditions. Release rates ranged from 1 to 20 kg h21. Ammonia and ethylene had five 5-min releases each to represent puff releases and five 20-min releases each to represent plume releases. Propylene had five 5-min puffs, six 20-min plumes, and a single 30-min plume. Thirty-two separate releases ranging from 6 to 47 min were conducted, of which only 30 releases generated useful data. The data collected included release rates, atmospheric concentrations to 100 m from the release point, and local meteorological conditions. The diagnostics included nine meteorological stations on 100-m centers and 36 photoionization detectors in a radial pattern. Three current stateof- the-practice models, Aerial locations of Hazardous Atmospheres (ALOHA), Emergency Prediction Information code (EPIcode), and Second-Order Closure Integrated Puff (SCIPUFF), were used to try to duplicate the measured field results. Low wind speeds are difficult to model, and all of the models had difficulty replicating the field measurements. However, the work does show that these models, if used correctly, are conservative (overpredict concentrations) and can be used for safety and emergency planning.

  16. The Implications of Extreme Outflows from Extreme Starbursts

    OpenAIRE

    Heckman, Timothy M.; Borthakur, Sanchayeeta

    2016-01-01

    Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along ...

  17. The Neutral Hydrogen Content of Galaxies in Cosmological Hydrodynamic Simulations

    CERN Document Server

    Davé, Romeel; Oppenheimer, Benjamin D; Kollmeier, Juna A; Weinberg, David H

    2013-01-01

    We examine the global HI properties of galaxies in quarter-billion particle cosmological hydrodynamic simulations, focusing on how our main adjustable physical process, galactic outflows, impacts HI content. In addition to the three outflow models considered in our earlier papers, we present a new one (ezw) motivated by high resolution interstellar medium simulations, in which the scalings of wind speeds and mass loading factors follow those expected for momentum-driven outflows for larger galaxies, and energy-driven outflows for dwarfs (sigma<75 km/s). To obtain predicted HI masses, we employ a simple but effective local correction for particle self-shielding, as well as an observationally-constrained transition from neutral to molecular hydrogen. We find that our ezw model produces an HI mass function whose shape agrees well with observations from the ALFALFA survey, having a low mass end slope of -1.3, while other models agree less well. Outflows critically govern the HI content in low-mass galaxies, wi...

  18. Powerful Outflows and Feedback from Active Galactic Nuclei

    CERN Document Server

    King, Andrew

    2015-01-01

    Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\\sim 0.1- 0.2c$ are a common feature in X--ray spectra of luminous AGN, offering a plausible physical origin for the well known connections between the hole and properties of its host. Observability constraints suggest that the winds must be episodic, and detectable only for a few percent of their lifetimes. The most powerful wind feedback, establishing the $M -\\sigma$ relation, is probably not directly observable at all. The $M - \\sigma$ relation signals a global change in the nature of AGN feedback. At black hole masses below $M-\\sigma$ feedback is confined to the immediate vicinity of the hole. At the $M-\\sigma$ mass it becomes much more energetic and widespread, and can drive away much of the bulge gas as a fast molecular outflow.

  19. A high-velocity transient outflow in Eta Carinae

    CERN Document Server

    Behar, Ehud; Soker, Noam

    2007-01-01

    We analyze velocity profiles of the X-ray spectral lines emitted by the Eta Carinae stellar binary at four epochs, just before the X-ray minimum (associated with periastron) and more than two years before the minimum (~apastron). The profiles are nicely resolved by the HETGS spectrometer on board Chandra. Far from periastron, we find symmetrical lines that are more or less centered at zero velocity. Closer to periastron, the lines broaden, shift towards the blue, and become visibly asymmetric. While the quiescent X-ray emission and slight (<200 km/sec) centroid shifts can be ascribed to the ordinary continuous binary wind interaction and to the orbital velocity of the secondary star, the observed high-velocity emission up to ~2,000 km/sec and the abrupt flares during which it occurs can not. This leads us to interpret the high-velocity flaring emission as due to a fast collimated outflow of ionized gas.

  20. Shocked molecular hydrogen in the bipolar outflow NGC 2071

    Energy Technology Data Exchange (ETDEWEB)

    Burton, M.G. (Edinburgh Univ. (UK). Dept. of Astronomy; National Aeronautics and Space Administration, Moffett Field, CA (USA). Ames Research Center); Geballe, T.R. (Joint Astronomy Centre, Hilo, Hawaii (USA); Foundation for Astronomical Research in the Netherlands (ASTRON)); Brand, P.W.J.L. (Edinburgh Univ. (UK). Dept. of Astronomy)

    1989-06-15

    Emission from the 4u = 1 - 0 S(1) line of molecular hydrogen has been mapped in the bipolar outflow NGC 2071. The line emission peaks at six positions distributed irregularly along the two lobes, which extend over a distance of {similar to} 1 pc. These lobes are parallel to, but offset {similar to} 20 arcsec from, the lobes of high-velocity CO line emission. Spectra from 2.1 to 2.45 {mu}m of the H{sub 2} emission lines are typical of shock-excited emission. The total H{sub 2} line luminosity is estimated to be {similar to} 4.5 time the solar luminosity. Profiles of the 1-0 S(1) line are relatively narrow (< 30 km s{sup -1} FWHM) for shocked gas. The peak velocity varies systematically across the source, in a manner consistent with the observed bipolarity of the millimetre-wave CO line emission. (author).

  1. Jet acceleration of the fast molecular outflows in the Seyfert galaxy IC 5063.

    Science.gov (United States)

    Tadhunter, C; Morganti, R; Rose, M; Oonk, J B R; Oosterloo, T

    2014-07-24

    Massive outflows driven by active galactic nuclei are widely recognized to have a key role in the evolution of galaxies, by heating the ambient gas, expelling it from the nuclear regions, and thereby affecting the star-formation histories of the galaxy bulges. It has been proposed that the powerful jets of relativistic particles (such as electrons) launched by some active nuclei can both accelerate and heat the molecular gas, which often dominates the mass budgets of the outflows. Clear evidence for this mechanism, in the form of detailed associations between the molecular gas kinematics and features in the radio-emitting jets, has however been lacking. Here we report that the warm molecular hydrogen gas in the western radio lobe of the Seyfert galaxy IC 5063 is moving at high velocities-up to about 600 kilometres per second-relative to the galaxy disk. This suggests that the molecules have been accelerated by fast shocks driven into the interstellar medium by the expanding radio jets. These results demonstrate the general feasibility of accelerating molecular outflows in fast shocks driven by active nuclei.

  2. Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

    Science.gov (United States)

    Mou, Guobin; Wang, Tinggui; Yang, Chenwei

    2017-07-01

    The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

  3. Neutral Operator and Neutral Differential Equation

    Directory of Open Access Journals (Sweden)

    Jingli Ren

    2011-01-01

    Full Text Available In this paper, we discuss the properties of the neutral operator (Ax(t=x(t−cx(t−δ(t, and by applying coincidence degree theory and fixed point index theory, we obtain sufficient conditions for the existence, multiplicity, and nonexistence of (positive periodic solutions to two kinds of second-order differential equations with the prescribed neutral operator.

  4. Modelling the neutralisation process in neutral beam injectors

    OpenAIRE

    Fitzgerald, Niall J.

    2009-01-01

    High power neutral beams currently play an important role in heating, fuelling and diagnosing magnetically confined thermonuclear fusion plasmas. At the Joint European Torus (JET) in Oxfordshire, England, the formation of such a beam involves passing a positive ion beam through a neutral gas target wherein beam electron-capture collisions result in a neutral beam component. The subsequent beam injection into the fusion plasma requires the sole use of this neutral component, since the charged ...

  5. Are bioenergy production systems carbon neutral? An overview of the work of IEA Bioenergy Task 38 on greenhouse gas balances of biomass and bioenergy systems

    Energy Technology Data Exchange (ETDEWEB)

    Cowie, A.; George, B. [Univ. of New England, Armidale, NSW (Australia)

    2010-07-01

    The bioenergy industry is growing rapidly in response to concerns over climate change and high oil prices. However, there are serious concerns about the sustainability of the industry, as well as about the environmental impacts of off-site activities. The International Energy Agency's (IEA) Task 38 was established to develop a method of calculating the net greenhouse gas (GHG) mitigation benefit of bioenergy and sequestration projects. Task 38 focuses on the methods used to assess the GHG benefits of bioenergy systems when compared with fossil fuel systems. A full life cycle approach was used to assess the GHG emissions associated with the production and handling of biomass, as well as the nitrous oxide (N{sub 2}O) emissions emitted from fertilized soils, and emissions resulting from the production of fertilizer, herbicide, and the manufacture and construction of power stations. Methods for including indirect land use change where biomass production is displacing food production are also being discussed as part of the task. To date, the study has indicated that materials substitution or co-firing applications have greater mitigation benefits than other bioenergy systems.

  6. Outflow and Accretion in Massive Star Forming Regions

    CERN Document Server

    Klaassen, P D

    2007-01-01

    In order to distinguish between the various components of massive star forming regions (i.e. infalling, outflowing and rotating gas structures) within our own Galaxy, we require high angular resolution observations which are sensitive to structures on all size scales. To this end, we present observations of the molecular and ionized gas towards massive star forming regions at 230 GHz from the SMA (with zero spacing from the JCMT) and at 22 and 23 GHz from the VLA at arcsecond or better resolution. These observations (of sources such as NGC7538, W51e2 and K3-50A) form an integral part of a multi-resolution study of the molecular and ionized gas dynamics of massive star forming regions (i.e. Klaassen & Wilson 2007). Through comparison of these observations with 3D radiative transfer models, we hope to be able to distinguish between various modes of massive star formation, such as ionized or halted accretion (i.e Keto 2003 or Klaassen et al. 2006 respectively).

  7. Line-emitting galaxies beyond a redshift of 7: an improved method for estimating the evolving neutrality of the intergalactic medium

    Energy Technology Data Exchange (ETDEWEB)

    Schenker, Matthew A.; Ellis, Richard S.; Konidaris, Nick P. [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Stark, Daniel P., E-mail: schenker@astro.caltech.edu [Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2014-11-01

    The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha (Lyα) emission, x {sub Lyα} has become the most valuable constraint on the evolving neutrality of the early intergalactic medium. However, in addition to resonant scattering by neutral gas, the visibility of Lyα is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content, and the nature of outflowing gas. Taking advantage of significant progress we have made in determining the line-emitting properties of z ≅ 4-6 galaxies, we propose an improved method, based on using the measured slopes of the rest-frame ultraviolet continua of galaxies, to interpret the growing body of near-infrared spectra of z > 7 galaxies in order to take into account these host galaxy dependencies. In a first application of our new method, we demonstrate its potential via a new spectroscopic survey of 7 < z < 8 galaxies undertaken with the Keck MOSFIRE spectrograph. Together with earlier published data, our data provide improved estimates of the evolving visibility of Lyα, particularly at redshift z ≅ 8. As a by-product, we also present a promising new line-emitting galaxy candidate, detected at 4.0σ at redshift z = 7.62. We discuss the improving constraints on the evolving neutral fraction over 6 < z < 8 and the implications for cosmic reionization.

  8. HH 223: a parsec-scale H2 outflow in the star-forming region L723

    CERN Document Server

    Lopez, R; Gomez, G; Estalella, R; Carrasco-Gonzalez, C

    2010-01-01

    The dark cloud Lynds 723 (L723) is a low-mass star-forming region where one of the few known cases of a quadrupolar CO outflow has been reported. Two recent works have found that the radio continuum source VLA 2, towards the centre of the CO outflow, is actually a multiple system of young stellar objects (YSOs). Several line-emission nebulae that lie projected on the east-west CO outflow were detected in narrow-band Halpha and [SII] images. The spectra of the knots are characteristic of shock-excited gas (Herbig-Haro spectra), with supersonic blueshifted velocities, which suggests an optical outflow also powered by the VLA 2 YSO system of L723. We imaged a field of ~5' X 5' centred on HH 223, which includes the whole region of the quadrupolar CO outflow with nir narrow-band filters . The H2 line-emission structures appear distributed over a region of 5.5' (0.5 pc for a distance of 300 pc) at both sides of the VLA 2 YSO system, with an S-shape morphology, and are projected onto the east-west CO outflow. Most o...

  9. Diagnostics of AGN-driven Molecular Outflows in ULIRGs from Herschel-PACS Observations of OH at 119um

    CERN Document Server

    Spoon, H W W; Lebouteiller, V; Gonzalez-Alfonso, E; Bernard-Salas, J; Urrutia, T; Rigopoulou, D; Westmoquette, M S; Smith, H A; Afonso, J; Pearson, C; Cormier, D; Efstathiou, A; Borys, C; Verma, A; Etxaluze, M; Clements, D L

    2013-01-01

    We report on our observations of the 79 and 119um doublet transitions of OH for 24 local (z<0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH119 profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to 2000 km/s, with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km/s (1000 km/s). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km/s are thought to require an active galactic nucleus (AGN) to drive them, about 2/3 of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the...

  10. Line Emitting Galaxies Beyond a Redshift of 7: An Improved Method for Estimating the Evolving Neutrality of the Intergalactic Medium

    CERN Document Server

    Schenker, Matthew A; Konidaris, Nick P; Stark, Daniel P

    2014-01-01

    The redshift-dependent fraction of color-selected galaxies revealing Lyman alpha emission has become the most valuable constraint on the evolving neutrality of the early intergalactic medium. However, in addition to resonant scattering by neutral gas, the visibility of Lyman alpha is also dependent on the intrinsic properties of the host galaxy, including its stellar population, dust content and the nature of outflowing gas. Taking advantage of significant progress we have made in determining the line emitting properties of $z \\simeq 4-6$ galaxies, we propose an improved method, based on using the measured slopes of the rest-frame ultraviolet continua of galaxies, to interpret the growing body of near-infrared spectra of $z>7$ galaxies in order to take into account these host galaxy dependencies. In a first application of our new method, we demonstrate its potential via a new spectroscopic survey of $7

  11. Directly Imaging Damped Ly-Alpha Galaxies at Redshifts Greater Than 2. III: The Star Formation Rates of Neutral Gas Reservoirs at Redshifts of Approximately 2.7

    Science.gov (United States)

    Fumagalli, Michele; OMeara, John M.; Prochaska, J. Xavier; Rafelski, Marc; Kanekar, Nissim

    2014-01-01

    We present results from a survey designed to probe the star formation properties of 32 damped Ly alpha systems (DLAs) at redshifts of approximately 2.7. By using the "double-DLA" technique that eliminates the glare of the bright background quasars, we directly measure the rest-frame FUV flux from DLAs and their neighbouring galaxies. At the position of the absorbing gas, we place stringent constraints on the unobscured star formation rates (SFRs) of DLAs to 2 sigma limits of psi less than 0.09-0.27 solar mass yr(exp -1), corresponding to SFR surface densities sigma(sub sfr) less than 10(exp -2.6)-10(exp -1.5) solar mass yr(exp -1) kpc(exp -2). The implications of these limits for the star formation law, metal enrichment, and cooling rates of DLAs are examined. By studying the distribution of impact parameters as a function of SFRs for all the galaxies detected around these DLAs, we place new direct constraints on the bright end of the UV luminosity function of DLA hosts. We find that less than or equal to 13% of the hosts have psi greater than or equal to 2 solar mass yr(exp -1) at impact parameters b(sub dla) less than or equal to (psi/solar mass yr(exp -1))(exp 0.8) + 6 kpc, differently from current samples of confirmed DLA galaxies. Our observations also disfavor a scenario in which the majority of DLAs arise from bright LBGs at distances 20 less than or equal to b(sub dla) less than 100 kpc. These new findings corroborate a picture in which DLAs do not originate from highly star forming systems that are coincident with the absorbers, and instead suggest that DLAs are associated with faint, possibly isolated, star-forming galaxies. Potential shortcomings of this scenario and future strategies for further investigation are discussed.

  12. Influence of Mediterranean Outflow on climate

    Science.gov (United States)

    Rahmstorf, Stefan

    A cover article in Eos last year [Johnson, 1997] called for a dam across the Strait of Gibraltar to prevent a new Ice Age. In this article, R. G. Johnson argued that reduced Nile River flow after building the Aswan Dam increases Mediterranean Sea salinity, leading to enhanced outflow of salty water into the Atlantic Ocean. This, in turn, would alter the thermohaline (that is, temperature and salinity driven) circulation of the Atlantic, heat up the Labrador Sea and enhance evaporation there, and increase snowfall in Canada until a new ice sheet builds up. Ocean circulation model experiments, however, suggest that this fear is unfounded. While Mediterranean saltwater outflow (Figure 1a) does appear to have some effect on North Atlantic circulation and surface climate, the change in Mediterranean salt budget resulting from the Aswan Dam is far too small to have any noticeable impact.

  13. Hepatic venous outflow obstruction: Three similar syndromes

    Institute of Scientific and Technical Information of China (English)

    Ulas Darda Bayraktar; Soley Seren; Yusuf Bayraktar

    2007-01-01

    Our goal is to provide a detailed review of venoocclusive disease (VOD), Budd-Chiari syndrome (BCS),and congestive hepatopathy (CH), all of which results in hepatic venous outflow obstruction. This is the first article in which all three syndromes have been reviewed,enabling the reader to compare the characteristics of these disorders. The histological findings in VOD, BCS,and CH are almost identical: sinusoidal congestion and cell necrosis mostly in perivenular areas of hepatic acini which eventually leads to bridging fibrosis between adjacent central veins. Tender hepatomegaly with jaundice and ascites is common to all three conditions.However, the clinical presentation depends mostly on the extent and rapidity of the outflow obstruction.Although the etiology and treatment are completely different in VOD, BCS, and CH; the similarities in clinical manifestations and liver histology may suggest a common mechanism of hepatic injury and adaptation in response to increased sinusoidal pressure.

  14. Protostellar outflows with Smoothed Particle Magnetohydrodynamics (SPMHD)

    CERN Document Server

    Bürzle, Florian; Stasyszyn, Federico; Dolag, Klaus; Klessen, Ralf S

    2011-01-01

    The protostellar collapse of a molecular cloud core is usually accompanied by outflow phenomena. The latter are thought to be driven by magnetorotational processes from the central parts of the protostellar disc. While several 3D AMR/nested grid studies of outflow phenomena in collapsing magnetically supercritical dense cores have been reported in the literature, so far no such simulation has been performed using the Smoothed Particle Hydrodynamics (SPH) method. This is mainly due to intrinsic numerical difficulties in handling magnetohydrodynamics within SPH, which only recently were partly resolved. In this work, we use an approach where we evolve the magnetic field via the induction equation, augmented with stability correction and divergence cleaning schemes. We consider the collapse of a rotating core of one solar mass, threaded by a weak magnetic field initially parallel to the rotation axis so that the core is magnetically supercritical. We show, that Smoothed Particle Magnetohydrodynamics (SPMHD) is a...

  15. Neutral Buoyancy Laboratory (NBL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility,...

  16. Hot Electromagnetic Outflows I: Acceleration and Spectra

    CERN Document Server

    Russo, Matthew

    2013-01-01

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such the breakout of a gamma-ray burst jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pushed inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid...

  17. Magnotospheric imaging of high latitude ion outflows

    Directory of Open Access Journals (Sweden)

    D. E. Garrido

    Full Text Available High latitude ion outflows mostly consist of upward streaming O+ and He+ emanating from the ionosphere. At heights above 1000 km, these flows consist of cold and hot components which resonantly scatter solar extreme ultraviolet (EUV light, however, the ion populations respond differently to Doppler shifting resulting from the large relative velocities between the ions and the Sun. The possibility of optical detection of the Doppler effect on the scattering rate will be discussed for the O+ (83.4 nm ions. We have contrasted the EUV solar resonance images of these outflows by simulations of the 30.4 nm He+ and 83.4 nm O+ emissions for both quiet and disturbed geomagnetic conditions. Input data for the 1000 km level has been obtained from the EICS instrument aboard the Dynamics Explorer satellite. Our results show emission rates of 50 and 56 milli-Rayleighs at 30.4 nm for quiet and disturbed conditions and 65 and 75 milli-Rayleighs at 83.4 nm for quiet and disturbed conditions, respectively, obtained for a polar orbiting satellite and viewing radially outward. We also find that an imager at an equatorial distance of 9 RE or more is in a favourable position for detecting ion outflows, particularly when the plasmapause is depressed in latitude. However, an occultation disk is necessary to obscure the bright plasmaspheric emissions.

  18. ITER neutral beam system US conceptual design

    Energy Technology Data Exchange (ETDEWEB)

    Purgalis, P.

    1990-09-01

    In this document we present the US conceptual design of a neutral beam system for International Thermonuclear Experimental Reactor (ITER). The design incorporates a barium surface conversion D{sup {minus}} source feeding a linear array of accelerator channels. The system uses a dc accelerator with electrostatic quadrupoles for strong focusing. A high voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and in the ion dump cavity to pump re-neutralized ions and neutralizer gas. All the above components are packaged in compact identical, independent modules which can be removed for remote maintenance. The neutral beam system delivers 75 MW of DO at 1.3 MeV, into three ports with a total of 9 modules arranged in stacks of three modules per port . To increase reliability each module is designed to deliver up to 10 MW; this allows eight modules operating at partial capacity to deliver the required power in the event one module is out of service, and provides 20% excess capacity to improve availability. Radiation protection is provided by shielding and by locating critical components in the source and accelerator 46.5 m from the torus centerline. Neutron shielding in the drift duct and neutralizer provides the added feature of limiting conductance and thus reducing gas flow to and from the torus.

  19. A Three Parsec-Scale Jet-Driven Outflow from Sgr A

    Science.gov (United States)

    Yusef-Zadeh, F.; Arendt, R.; Bushouse, H.; Cotton, W.; Haggard, D.; Pound, M. W.; Roberts, D. A.; Royster, M.; Wardle, M.

    2012-01-01

    The compact radio source Sgr A* is coincident with a 4x 10(exp 6) solar Mass black hole at the dynamical center of the Galaxy and is surrounded by dense orbiting ionized and molecular gas. We present high resolution radio continuum images of the central 3' and report a faint continuous linear structure centered on Sgr A*. This feature is rotated by 28 deg in PA with respect to the Galactic plane. A number of weak blobs of radio emission with X-ray counterparts are detected along the axis of the linear structure. In addition, the continuous linear feature appears to be terminated symmetrically by two linearly polarized structures at 8.4 GHz, approx 75" from Sgr A*. The linear structure is best characterized by a mildly relativistic jet-driven outflow from Sgr A*, and an outflow rate 10(exp 6) solar M / yr. The near and far-sides of the jet are interacting with orbiting ionized and molecular gas over the last 1-3 hundred years and are responsible for the origin of a 2" hole, the "minicavity", where disturbed kinematics, enhanced FeII/III line emission, and diffuse X-ray gas have been detected. The estimated kinetic luminosity of the outflow is approx 1.2 X 10(exp 41) erg/s which can produce the Galactic center X-ray flash that has recently been identified

  20. The Water Vapor Abundance in Orion KL Outflows

    CERN Document Server

    Cernicharo, J; Daniel, F; Lerate, M R; Barlow, M J; Swinyard, B M; Van Dishoeck, E F; Lim, T L; Viti, S; Yates, J

    2006-01-01

    We present the detection and modeling of more than 70 far-IR pure rotational lines of water vapor, including the 18O and 17O isotopologues, towards Orion KL. Observations were performed with the Long Wavelength Spectrometer Fabry-Perot (LWS/FP; R~6800-9700) on board the Infrared Space Observatory (ISO) between ~43 and ~197 um. The water line profiles evolve from P-Cygni type profiles (even for the H2O18 lines) to pure emission at wavelengths above ~100 um. We find that most of the water emission/absorption arises from an extended flow of gas expanding at 25+-5 kms^-1. Non-local radiative transfer models show that much of the water excitation and line profile formation is driven by the dust continuum emission. The derived beam averaged water abundance is 2-3x10^-5. The inferred gas temperature Tk=80-100 K suggests that: (i) water could have been formed in the "plateau" by gas phase neutral-neutral reactions with activation barriers if the gas was previously heated (e.g. by shocks) to >500 K and/or (ii) H2O for...

  1. A Robust Measurement of the Mass Outflow Rate of the Galactic Outflow from NGC 6090

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei

    2016-01-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si~{\\sc IV} absorption lines to calculate the scaling of velocity (v), covering fraction (C$_f$), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: $v \\propto(1 -R_i/r )^\\beta$ (were R$_i$ is the inner outflow radius). We find that the velocity ($\\beta$=0.43) is consistent with an outflow driven by an r$^{-2}$ force, while the scaling of the covering fraction ($C_f \\propto r^{-0.82}$) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of fou...

  2. High-velocity extended molecular outflow in the star-formation dominated luminous infrared galaxy ESO 320-G030

    CERN Document Server

    Pereira-Santaella, M; García-Burillo, S; Alonso-Herrero, A; Arribas, S; Cazzoli, S; Emonts, B; López, J Piqueras; Planesas, P; Bergmann, T Storchi; Usero, A; Villar-Martín, M

    2016-01-01

    We analyze new high spatial resolution (~60 pc) ALMA CO(2-1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d=48 Mpc) in combination with ancillary HST optical and near-IR imaging as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (~450 km/s) spatially resolved (size~2.5 kpc; dynamical time ~3 Myr) massive (~10^7 Msun; mass rate~2-8 Msun/yr) molecular outflow originated in the central ~250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 10^5.5 and 10^6.4 Msun. The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (~100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7x10^-5, which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow...

  3. Spectral-Line Survey at Millimeter and Submillimeter Wavelengths toward an Outflow-Shocked Region, OMC 2-FIR 4

    CERN Document Server

    Shimajiri, Yoshito; Kitamura, Yoshimi; Tsukagoshi, Takashi; Saito, Masao; Nakamura, Fumitaka; Momose, Munetake; Takakuwa, Shigehisa; Yamaguchi, Takahiro; Sakai, Nami; Yamamoto, Satoshi; Kawabe, Ryohei

    2015-01-01

    We performed the first spectral-line survey at 82--106 GHz and 335--355 GHz toward the outflow-shocked region, OMC 2-FIR 4, the outflow driving source, FIR 3, and the northern outflow lobe, FIR 3N. We detected 120 lines of 20 molecular species. The line profiles are found to be classifiable into two types: one is a single Gaussian component with a narrow ($$ 3km s$^{-1}$) widths. The narrow components for the most of the lines are detected at all positions, suggesting that they trace the ambient dense gas. For CO, CS, HCN, and HCO$^{+}$, the wide components are detected at all positions, suggesting the outflow origin. The wide components of C$^{34}$S, SO, SiO, H$^{13}$CN, HC$^{15}$N, H$_2^{13}$CO, H$_2$CS, HC$_3$N, and CH$_3$OH are detected only at FIR 4, suggesting the outflow-shocked gas origin. The rotation diagram analysis revealed that the narrow components of C$_2$H and H$^{13}$CO$^+$ show low temperatures of 12.5$\\pm$1.4 K, while the wide components show high temperatures of 20--70 K. This supports our...

  4. Unstable mass-outflows in geometrically thick accretion flows around black holes

    CERN Document Server

    Okuda, Toru

    2015-01-01

    Accretion flows around black holes generally result in mass-outflows that exhibit irregular behavior quite often. Using 2D time-dependent hydrodynamical calculations, we show that the mass-outflow is unstable in the cases of thick accretion flows such as the low angular momentum accretion flow and the advection-dominated accretion flow. For the low angular momentum flow, the inward accreting matter on the equatorial plane interacts with the outflowing gas along the rotational axis and the centrifugally supported oblique shock is formed at the interface of both the flows, when the viscosity parameter $\\alpha$ is as small as $\\alpha \\le 10^{-3}$. The hot and rarefied blobs, which result in the eruptive mass-outflow, are generated in the inner shocked region and grow up toward the outer boundary. The advection-dominated accretion flow attains finally in the form of a torus disc with the inner edge of the disc at $3R_{\\rm g} \\le r \\le 6R_{\\rm g}$ and the center at $6R_ {\\rm g} \\le r \\le 10R_{\\rm g}$, and a series...

  5. CHANG-ES VII: Magnetic outflows from the Virgo cluster galaxy NGC 4388

    CERN Document Server

    Damas-Segovia, Ancor; Vollmer, Bernd; Wiegert, Theresa; Krause, Marita; Irwin, Judith; Wezgowiec, Marek; Li, Jiang-Tao; Dettmar, Ralf-Jurgen; English, Jayanne; Wang, Q Daniel

    2016-01-01

    We investigate the effects of ram pressure on the ordered magnetic field of a galaxy hosting a radio halo and strong nuclear outflows. New radio images in total and polarized intensity of the edge-on Virgo galaxy NGC\\,4388 were obtained within the CHANG-ES EVLA project. The unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field. The nuclear outflow extends far into the halo to about 5\\,kpc from the center and is spatially correlated with the $\\rm{H}\\alpha$ and X-ray emission. For the first time, the southern outflow is detected. Above and below both spiral arms we find extended blobs of polarized emission with an ordered field oriented perpendicular to the disk. The synchrotron lifetime of the cosmic ray electrons (CREs) in these regions yields a mean outflow velocity of $(270\\pm70)\\kms$, in agreement with a galactic wind scenario. The observed symmetry of the polarized halo features in NGC 4388 excludes a compression of the halo gas by the ram pressure of th...

  6. A CATALOG OF METHANOL MASERS IN MASSIVE STAR-FORMING REGIONS. III. THE MOLECULAR OUTFLOW SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Ruiz, A. I. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis E. Erro 1, Tonantzintla, Puebla, C.P. 72840, México (Mexico); Kurtz, S. E.; Loinard, L. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apartado Postal 3-72, Morelia 58089, México (Mexico); Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States); Hofner, P. [New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States)

    2016-02-15

    We present an interferometric survey of the 44 GHz class I methanol maser transition toward a sample of 69 sources consisting of high-mass protostellar object (HMPO) candidates and ultracompact (UC) H ii regions. We found a 38% detection rate (16 of 42) in the HMPO candidates and a 54% detection rate (13 of 24) for the regions with ionized gas. This result indicates that class I methanol maser emission is more common toward the more evolved young stellar objects of our sample. Comparing with similar interferometric data sets, our observations show narrower linewidths, likely due to our higher spatial resolution. Based on a comparison between molecular outflow tracers and the maser positions, we find several cases where the masers appear to be located at the outflow interface with the surrounding core. Unlike previous surveys, we also find several cases where the masers appear to be located close to the base of the molecular outflow, although we cannot discard projection effects. This and other surveys of class I methanol masers not only suggest that these masers may trace shocks at different stages, but also that they may even trace shocks arising from a number of different phenomena occurring in star-forming regions: young/old outflows, cloud–cloud collisions, expanding H ii regions, among others.

  7. A Massive X-ray Outflow From The Quasar PDS 456

    Science.gov (United States)

    Reeves, J. N.; O'Brien, P. T.; Ward, M. J.

    2003-01-01

    We report on XMM-Newton spectroscopic observations of the luminous, radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, which can be attributed to a series of blue-shifted K-shell absorption edges due to highly ionized iron. The higher resolution soft X-ray grating RGS spectrum exhibits a broad absorption line feature near 1 keV, which can be modeled by a blend of L-shell transitions from highly ionized iron (Fe XVII - XXIV). An extreme outflow velocity of approx. 50000 km/s is required to model the K and L shell iron absorption present in the XMM-Newton data. Overall, a large column density (N(sub H) = 5 x 10(exp 23)/sq cm) of highly ionized gas (log xi = 2.5) is required in PDS 456. A large mass outflow rate of approx. 10 solar mass/year (assuming a conservative outflow covering factor of 0.1 steradian) is derived, which is of the same order as the overall mass accretion rate in PDS 456. This represents a substantial fraction (approx. 10%) of the quasar energy budget, whilst the large column and outflow velocity place PDS 456 towards the extreme end of the broad absorption line quasar population.

  8. Quantifying AGN-Driven Metal-Enhanced Outflows in Chemodynamical Simulations

    CERN Document Server

    Taylor, Philip

    2015-01-01

    We show the effects of AGN-driven outflows on the ejection of heavy elements using our cosmological simulations, where super-massive black holes originate from the first stars. In the most massive galaxy, we have identified two strong outflows unambiguously driven by AGN feedback. These outflows have a speed greater than $\\sim 8000$ km\\,s$^{-1}$ near the AGN, and travel out to a half Mpc with $\\sim 3000$ km\\,s$^{-1}$. These outflows remove the remaining gas ($\\sim 3$ per cent of baryons) and significant amounts of metals ($\\sim 2$ per cent of total produced metals) from the host galaxy, chemically enriching the circumgalactic medium (CGM) and the intergalactic medium (IGM). 17.6 per cent of metals from this galaxy, and 18.4 per cent of total produced metals in the simulation, end up in the CGM and IGM, respectively. The metallicities of the CGM and IGM are higher with AGN feedback, while the mass--metallicity relation of galaxies is not affected very much. We also find `selective' mass-loss where iron is more...

  9. Silicon Monoxide Observations Reveal a Cluster of Hidden Compact Outflows in the OMC1 South Region

    CERN Document Server

    Zapata, L A; Rodríguez, L F; O'Dell, C R; Zhang, Q; Muench, A; Zapata, Luis A.; Ho, Paul T. P.; Rodriguez, Luis F.; Zhang, Qizhou; Muench, August

    2006-01-01

    We present high angular resolution ($2\\rlap.{''}8 \\times 1\\rlap.{''}7$) SiO J=5$\\to$4; $v=0$ line observations of the OMC1S region in the Orion Nebula made using the Submillimeter Array (SMA). We detect for the first time a cluster of four compact bipolar and monopolar outflows that show high, moderate and low velocity gas and appear to be energized by millimeter and infrared sources associated with this region. The SiO molecular outflows are compact ($<$ 3500 AU), and in most of the cases, they are located very close to their exciting sources. We thus propose that the SiO thermal emission is tracing the youngest and most highly excited parts of the outflows which cannot be detected by other molecules. Moreover, since the ambient cloud is weak in the SiO line emission, these observations can reveal flows that in other molecular transitions will be confused with the ambient velocity cloud emission. Analysis of their positional-velocity diagrams show that some components of these outflows may be driven by wi...

  10. CHANG-ES. VII. Magnetic Outflows from the Virgo Cluster Galaxy NGC 4388

    Science.gov (United States)

    Damas-Segovia, A.; Beck, R.; Vollmer, B.; Wiegert, T.; Krause, M.; Irwin, J.; Weżgowiec, M.; Li, J.; Dettmar, R.-J.; English, J.; Wang, Q. D.

    2016-06-01

    We investigate the effects of ram pressure on the ordered magnetic field of a galaxy hosting a radio halo and strong nuclear outflows. New radio images in total and polarized intensity of the edge-on Virgo galaxy NGC 4388 were obtained within the CHANG-ES EVLA project. The unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field. The nuclear outflow extends far into the halo to about 5 kpc from the center and is spatially correlated with the {{H}}α and X-ray emission. For the first time, the southern outflow is detected. Above and below both spiral arms we find extended blobs of polarized emission with an ordered field oriented perpendicular to the disk. The synchrotron lifetime of the cosmic-ray electrons (CREs) in these regions yields a mean outflow velocity of 270+/- 70 {km} {{{s}}}-1, in agreement with a galactic wind scenario. The observed symmetry of the polarized halo features in NGC 4388 excludes a compression of the halo gas by the ram pressure of the intracluster medium (ICM). The assumption of equilibrium between the halo pressure and the ICM ram pressure yields an estimate of the ICM density that is consistent with both the ICM density derived from X-ray observations and the recent Planck Sunyaev-Zel’dovich measurements. The detection of a faint radio halo around cluster galaxies could thus be used for an estimate of ICM ram pressure.

  11. An Ordered Bipolar Outflow from a Massive Early-stage Core

    Science.gov (United States)

    Tan, Jonathan C.; Kong, Shuo; Zhang, Yichen; Fontani, Francesco; Caselli, Paola; Butler, Michael J.

    2016-04-01

    We present ALMA follow-up observations of two massive, early-stage core candidates, C1-N and C1-S, in IRDC G028.37+00.07, that were previously identified by their {{{N}}}2{{{D}}}+(3-2) emission, and show high levels of deuteration of this species. The cores are also dark at far-infrared wavelengths up to ˜ 100 μ {{m}}. We detect 12CO(2-1) from a narrow, highly collimated bipolar outflow that is being launched from near the center of the C1-S core, which is also the location of the peak 1.3 mm dust continuum emission. This protostar, C1-Sa, has associated dense gas traced by {{{C}}}18{{O}}(2-1) and DCN(3-2), from which we estimate that it has a radial velocity that is near the center of the range exhibited by the C1-S massive core. A second outflow-driving source is also detected within the projected boundary of C1-S, but it appears to be at a different radial velocity. After considering the properties of the outflows, we conclude that C1-Sa is a promising candidate for an early-stage massive protostar and as such it shows that these early phases of massive star formation can involve highly ordered outflow, and thus accretion, processes, similar to models developed to explain low-mass protostars.

  12. Mapping the Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble

    Science.gov (United States)

    Bordoloi, Rongmon; Fox, Andrew J.; Lockman, Felix J.; Wakker, Bart P.; Jenkins, Edward B.; Savage, Blair D.; Hernandez, Svea; Tumlinson, Jason; Bland-Hawthorn, Joss; Kim, Tae-Sun

    2017-01-01

    We report new observations from a systematic, spectroscopic, ultraviolet absorption-line survey that maps the spatial and kinematic properties of the high velocity gas in the Galactic Center (GC) region. We examine the hypothesis that this gas traces the biconical nuclear outflow. We use an ultraviolet spectra of 47 background QSOs and halo stars projected inside and outside the northern Fermi Bubble from the Hubble Space Telescope to study the incidence of high velocity absorption around it. We use five lines of sight inside the northern Fermi Bubble to constrain the velocity and column densities of outflowing gas traced by O i, Al ii, C ii, C iv, Si ii, Si iii, Si iv, and other species. We find that all five lines of sight inside the northern Fermi Bubble exhibit blueshifted high velocity absorption components, whereas only 9 out of the 42 lines of sight outside the northern Fermi Bubble exhibit blueshifted high velocity absorption components. The observed outflow velocity profile decreases with Galactic latitude and radial distance (R) from the GC. The observed blueshifted velocities change from {v}{GSR}=-265 {km} {{{s}}}-1 at R ≈ 2.3 kpc to {v}{GSR}=-91 {km} {{{s}}}-1 at R ≈ 6.5 kpc. We derive the metallicity of the entrained gas along the 1H1613-097 sightline, one that passes through the center of the northern Fermi Bubble, finding [O/H] ≳ -0.54 ± 0.15. A simple kinematic model, tuned to match the observed absorption component velocities along the five lines of sight inside the Bubble, constrains the outflow velocities to ≈1000-1300 {km} {{{s}}}-1, and the age of the outflow to be ˜6-9 Myr. We estimate a minimum mass outflow rate for the nuclear outflow to be ≳ 0.2{M}⊙ {{yr}}-1. Combining the age and mass outflow rates, we determine a minimum mass of total UV-absorbing cool gas entrained in the Fermi Bubbles to be ≳ 2× {10}6 {M}⊙ .

  13. High-velocity extended molecular outflow in the star-formation dominated luminous infrared galaxy ESO 320-G030

    Science.gov (United States)

    Pereira-Santaella, M.; Colina, L.; García-Burillo, S.; Alonso-Herrero, A.; Arribas, S.; Cazzoli, S.; Emonts, B.; Piqueras López, J.; Planesas, P.; Storchi Bergmann, T.; Usero, A.; Villar-Martín, M.

    2016-10-01

    We analyze new high spatial resolution (~60 pc) ALMA CO(2-1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d = 48 Mpc) in combination with ancillary Hubble Space Telescope optical and near infrared (IR) imaging, as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (~450 km s-1) spatially resolved (size~2.5 kpc; dynamical time ~3 Myr) massive (~107 M⊙; Ṁ ~ 2-8 M⊙ yr-1) molecular outflow that has originated in the central ~250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 105.5 and 106.4 M⊙. The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (~100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7 × 10-5, which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow. The nuclear IR and radio properties are compatible with strong and highly obscured star-formation (Ak ~ 4.6 mag; star formation rate ~ 15 M⊙ yr-1). We do not find any evidence for the presence of an active galactic nucleus. We estimate that supernova explosions in the nuclear starburst (νSN ~ 0.2 yr-1) can power the observed molecular outflow. The kinetic energy and radial momentum of the cold molecular phase of the outflow correspond to about 2% and 20%, respectively, of the supernovae output. The cold molecular outflow velocity is lower than the escape velocity, so the gas will likely return to the galaxy disk. The mass loading factor is ~0.1-0.5, so the negative feedback owing to this star-formation-powered molecular outflow is probably limited. The reduced images and datacubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  14. Variation in cell wall composition among forage maize (Zea mays L.) inbred lines and its impact on digestibility: analysis of neutral detergent fiber composition by pyrolysis-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Fontaine, Anne-Sophie; Bout, Siobhán; Barrière, Yves; Vermerris, Wilfred

    2003-12-31

    Cell wall digestibility is an important determinant of forage quality, but the relationship between cell wall composition and digestibility is poorly understood. We analyzed the neutral detergent fiber (NDF) fraction of nine maize inbred lines and one brown midrib3 mutant with pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Among 29 pyrolysis fragments that were quantified, two carbohydrate-derived and six lignin-derived fragments showed statistically significant genetic variation. The pyrolysis products 4-vinyl phenol and 2,6-dimethoxy-4-vinyl phenol were negatively correlated with digestibility, whereas furfural and 3-(4-hydroxyphenyl)-3-oxopropanal showed a positive correlation with digestibility. Linear discriminant analysis of the pyrolysis data resulted in the resolution of groups of inbred lines with different digestibility properties based on their chemical composition. These analyses reveal that digestibility is governed by complex interactions between different cell wall compounds, but that several pyrolysis fragments can be used as markers to distinguish between maize lines with different digestibility.

  15. The SILCC project - III. Regulation of star formation and outflows by stellar winds and supernovae

    Science.gov (United States)

    Gatto, Andrea; Walch, Stefanie; Naab, Thorsten; Girichidis, Philipp; Wünsch, Richard; Glover, Simon C. O.; Klessen, Ralf S.; Clark, Paul C.; Peters, Thomas; Derigs, Dominik; Baczynski, Christian; Puls, Joachim

    2017-04-01

    We study the impact of stellar winds and supernovae on the multiphase interstellar medium using three-dimensional hydrodynamical simulations carried out with FLASH. The selected galactic disc region has a size of (500 pc)2 × ±5 kpc and a gas surface density of 10 M⊙ pc-2. The simulations include an external stellar potential and gas self-gravity, radiative cooling and diffuse heating, sink particles representing star clusters, stellar winds from these clusters that combine the winds from individual massive stars by following their evolution tracks, and subsequent supernova explosions. Dust and gas (self-) shielding is followed to compute the chemical state of the gas with a chemical network. We find that stellar winds can regulate star (cluster) formation. Since the winds suppress the accretion of fresh gas soon after the cluster has formed, they lead to clusters that have lower average masses (102-104.3 M⊙) and form on shorter time-scales (10-3-10 Myr). In particular, we find an anticorrelation of cluster mass and accretion time-scale. Without winds, the star clusters easily grow to larger masses for ∼5 Myr until the first supernova explodes. Overall, the most massive stars provide the most wind energy input, while objects beginning their evolution as B-type stars contribute most of the supernova energy input. A significant outflow from the disc (mass loading ≳1 at 1 kpc) can be launched by thermal gas pressure if more than 50 per cent of the volume near the disc mid-plane can be heated to T > 3 × 105 K. Stellar winds alone cannot create a hot volume-filling phase. The models that are in best agreement with observed star formation rates drive either no outflows or weak outflows.

  16. Stellar Populations, Outflows, and Morphologies of High-Redshift Galaxies

    Science.gov (United States)

    Kornei, Katherine Anne

    Understanding the regulation and environment of star formation across cosmic time is critical to tracing the build-up of mass in the Universe and the interplay between the stars and gas that are the constituents of galaxies. Three studies are presented in this thesis, each examining a different aspect of star formation at a specific epoch. The first study presents the results of a photometric and spectroscopic survey of 321 Lyman break galaxies (LBGs) at z ˜ 3 to investigate systematically the relationship between Lyalpha emission and stellar populations. Lyalpha equivalent widths were calculated from rest-frame UV spectroscopy and optical/near-infrared/Spitzer photometry was used in population synthesis modeling to derive the key properties of age, dust extinction, star formation rate (SFR), and stellar mass. Using a variety of statistical tests, we find that Lyalpha equivalent width and age, SFR, and dust extinction, respectively, are significantly correlated in the sense that objects with strong Lyalpha emission also tend to be older, lower in star formation rate, and less dusty than objects with weak Lyalpha emission, or the line in absorption. We accordingly conclude that, within the LBG sample, objects with strong Lyalpha emission represent a later stage of galaxy evolution in which supernovae-induced outflows have reduced the dust covering fraction. The second study focuses specifically on galactic-scale outflowing winds in 72 star-forming galaxies at z ˜ 1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering SiII, CIV, FeII, MgII, and MgI lines in the rest-frame ultraviolet. Using GALEX, HST, and Spitzer imaging available for the Extended Groth Strip, we examine galaxies on a per-object basis in order to better understand both the prevalence of galactic outflows at z ˜ 1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from

  17. Collimated Outflows in the Stingray Nebula (He 3-1357)

    Science.gov (United States)

    Bobrowsky, M.; Sahu, K. C.; Parthasarathy, M.; Garcia-Lario, P.

    1997-12-01

    Observations over the past four decades have revealed significant changes in the spectrum of the Stingray Nebula (He 3-1357). Here we present HST images and spectra showing the most recent developments. In 1950, Henize saw only Hα in emission; but more recent observations by Parthasarathy et al. in 1992 showed strong forbidden lines consistent with a young planetary nebula. The spherically aberrated 1992 HST images, in which Bobrowsky first optically resolved the nebula, showed a compact nebula surrounding the central star. Nebular gas appeared most strongly concentrated in an ellipse with its major axis subtending 1.('') 6 from NE to SW. If this ellipse is actually a circular ring viewed obliquely, then our line of sight is inclined from the symmetry axis by 56deg . Above and below the ring of gas are two bubbles containing lower-density gas. At the tip of each bubble, there is a hole where the gas inside the bubbles has broken through and is now escaping. While images of focused jets have been obtained previously (Borkowski et al.), this is the first case where the nebular structure responsible for the focusing of an outflow can be clearly seen. The windblown appearance of the nebula is consistent with the blueshifted Si IV (1394-1403 Angstroms) and Al III (1855-1863 Angstroms) doublets observed by Parthasarathy et al. that indicated the presence of a strong stellar wind. The N V (1239-1243 Angstroms) to C IV (1548-1551 Angstroms) ratio has increased in recent years, consistent with a young nebula becoming increasingly ionized. Our new spectra reveal additional developments that show the real-time development of this young nebula. Finally, the new HST Planetary Camera images of the nebula show detailed structure indicating a much more complex object than previously known, including the presence of a companion star 0.('') from the central star.

  18. Dispersal of dense protostellar material - NH3 hot cores and outflows in Sagittarius B2

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, S.N.; Genzel, R.; Palmer, P.

    1987-05-01

    VLA observations of Sgr B2 in six ammonia transitions have uncovered two 200-K condensations with approximately 0.2 pc diameters associated with water maser sources which are similar to the Orion hot core but are more massive. Total NH3 mass of the northern source is 1000 times higher than in the Orion hot core. The hot core emission traces dense gas around newly formed massive stars, and is produced during a relatively brief stage after the star begins to heat the surrounding medium and before the dense gas is dispersed by outflow and the emergence of an expanding H II region. 36 references.

  19. Ion-Neutral Coupling in Solar Prominences

    Science.gov (United States)

    Gilbert, Holly

    2011-01-01

    Interactions between ions and neutrals in a partially ionized plasma are important throughout heliophysics, including near the solar surface in prominences. Understanding how ion-neutral coupling affects formation, support, structure, and dynamics of prominences will advance our physical understanding of magnetized systems involving a transition from a weakly ionized dense gas to a fully ionized tenuous plasma. We address the fundamental physics of prominence support, which is normally described in terms of a magnetic force on the prominence plasma that balances the solar gravitational force, and the implications for observations. Because the prominence plasma is only partially ionized, it is necessary to consider the support of the both the ionized and neutral components. Support of the neutrals is accomplished through a frictional interaction between the neutral and ionized components of the plasma, and its efficacy depends strongly on the degree of ionization of the plasma. More specifically, the frictional force is proportional to the relative flow of neutral and ion species, and for a sufficiently weakly ionized plasma, this flow must be relatively large to produce a frictional force that balances gravity. A large relative flow, of course, implies significant draining of neutral particles from the prominence. We evaluate the importance of this draining effect for a hydrogen-helium plasma, and consider the observational evidence for cross-field diffusion of neutral prominence material.

  20. Extreme-Velocity Quasar Outflows and the Role of X-ray Shielding

    CERN Document Server

    Hamann, Fred; McGraw, Sean; Hidalgo, Paola Rodriguez; Shields, Joseph; Capellupo, Daniel; Charlton, Jane; Eracleous, Michael

    2013-01-01

    Quasar accretion disk winds observed via broad absorption lines (BALs) in the UV produce strong continuous absorption in X-rays. The X-ray absorber is believed to serve critically as a radiative shield to enable radiative driving. However, "mini-BAL" and narrow absorption line outflows have dramatically less X-ray absorption than BALs. Here we examine X-ray and rest-frame UV spectra of 8 mini-BAL quasars with outflow speeds in the range 0.1c to 0.2c to test whether extreme speeds require a strong shield. We find that the X-ray absorption is weak or moderate, with neutral-equivalent column densities N_H ~ 8 x 10^15 cm (based on measured line depths), the outflows have shapes like thin "pancakes" viewed face-on, or they occupy larger volumes like a spray of many dense clouds with a small volume filling factor. These results favor models with magnetic confinement in magnetic disk winds.

  1. A resolved outflow of matter from a Brown Dwarf

    CERN Document Server

    Whelan, E T; Bacciotti, F; Natta, A; Testi, L; Randich, S; Whelan, Emma T.; Ray, Thomas P.; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

    2005-01-01

    The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs amongst newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

  2. A resolved outflow of matter from a brown dwarf.

    Science.gov (United States)

    Whelan, Emma T; Ray, Thomas P; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

    2005-06-01

    The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs among newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

  3. Interferometric Mapping of Perseus Outflows with MASSES

    Science.gov (United States)

    Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

    2017-01-01

    The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

  4. Functional Anatomy of the Outflow Facilities.

    Science.gov (United States)

    Pizzirani, Stefano; Gong, Haiyan

    2015-11-01

    In order to understand the pathophysiology, select optimal therapeutic options for patients and provide clients with honest expectations for cases of canine glaucoma, clinicians should be familiar with a rational understanding of the functional anatomy of the ocular structures involved in this group of diseases. The topographical extension and the structural and humoral complexity of the regions involved with the production and the outflow of aqueous humor undergo numerous changes with aging and disease. Therefore, the anatomy relative to the fluid dynamics of aqueous has become a pivotal yet flexible concept to interpret the different phenotypes of glaucoma.

  5. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Lockman, F. J. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Dickey, J. M. [School of Physics and Mathematics, University of Tasmania, TAS 7001 (Australia); Gaensler, B. M.; Green, A. J., E-mail: naomi.mcclure-griffiths@csiro.au [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

    2013-06-10

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

  6. Outflows vs. Clouds in AGN Intrinsic Absorbers

    OpenAIRE

    Arav, Nahum

    2003-01-01

    We discuss the crucial role of a dynamical picture in the analysis of AGN intrinsic absorbers data. High quality FUSE data of Mrk 279 are used to demonstrate that the line of sight covering fraction is a strong function of velocity. In Mrk 279, as well as in most cases where the data is of high enough quality, the shape of the absorption troughs is mainly determined by the velocity-dependent covering fraction. We argue that the traditional ``cloud'' picture of AGN outflows is hard pressed to ...

  7. Suzaku Discovery of Ultra-fast Outflows in Radio-loud AGN

    Science.gov (United States)

    Sambruna, Rita M.; Tombesi, F.; Reeves, J.; Braito, V.; Gofford, J.; Cappi, M.

    2010-03-01

    We present the results of an analysis of the 3.5--10.5 keV spectra of five bright Broad-Line Radio Galaxies (BLRGs) using proprietary and archival Suzaku observations. In three sources -- 3C 111, 3C 120, and 3C 390.3 -- we find evidence, for the first time in a radio-loud AGN, for absorption features at observed energies 7 keV and 8--9 keV, with high significance according to both the F-test and extensive Monte Carlo simulations (99% or larger). In the remaining two BLRGs, 3C 382 and 3C 445, there is no evidence for such absorption features in the XIS spectra. If interpreted as due to Fe XXV and/or Fe XXVI K-shell resonance lines, the absorption features in 3C 111, 3C 120, and 3C 390.3 imply an origin from an ionized gas outflowing with velocities in the range v 0.04-0.15c, reminiscent of Ultra-Fast Outflows (UFOs) previously observed in radio-quiet Seyfert galaxies. A fit with specific photoionization models gives ionization parameters log ξ 4--5.6 erg s-1 cm and column densities of NH 1022-23 cm-2, similar to the values observed in Seyferts. Based on light travel time arguments, we estimate that the UFOs in the three BLRGs are located within 20--500 gravitational radii from the central black hole, and thus most likely are connected to disk winds/outflows. Our estimates show that the UFOs mass outflow rate is comparable to the accretion rate and their kinetic energy a significant fraction of the AGN bolometric luminosity, making these outflows significant for the global energetic of these systems, in particular for mechanisms of jet formation.

  8. Polytropic transonic galactic outflows in a dark matter halo with a central black hole

    Science.gov (United States)

    Igarashi, Asuka; Mori, Masao; Nitta, Shin-ya

    2017-09-01

    Polytropic transonic solutions of spherically symmetric and steady galactic winds in the gravitational potential of a dark matter halo (DMH) with a supermassive black hole (SMBH) are studied. The solutions are classified in terms of their topological features, and the gravitational potential of the SMBH adds a new branch to the transonic solutions generated by the gravity of the DMH. The topological types of the transonic solutions depend on the mass distribution, the amount of supplied energy, the polytropic index γ and the slope α of the DMH mass distribution. When α becomes larger than a critical value αc, the transonic solution types change dramatically. Further, our model predicts that it is possible for a slowly accelerating outflow to exist, even in quiescent galaxies with small γ. This slowly accelerating outflow differs from those considered in many of the previous studies focusing on supersonic outflows in active star-forming galaxies. In addition, our model indicates that outflows in active star-forming galaxies have only one transonic point in the inner region (∼0.01 kpc). The locus of this transonic point does not strongly depend on γ. We apply the polytropic model incorporating mass flux supplied by stellar components to the Sombrero galaxy, and conclude that it can reproduce the observed gas density and the temperature distribution well. This result differs significantly from the isothermal model, which requires an unrealistically large mass flux. Thus, we conclude that the polytropic model is more realistic than the isothermal model, and that the Sombrero galaxy can have a slowly accelerating outflow.

  9. FAR-ULTRAVIOLET OBSERVATIONS OF OUTFLOWS FROM INFRARED-LUMINOUS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Leitherer, Claus; Wofford, Aida [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Chandar, Rupali [Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606 (United States); Tremonti, Christy A. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Schaerer, Daniel, E-mail: leitherer@stsci.edu, E-mail: wofford@stsci.edu, E-mail: Rupali.Chandar@utoledo.edu, E-mail: tremonti@astro.wisc.edu, E-mail: daniel.schaerer@unige.ch [Observatoire de Geneve, 51 chemin des Maillettes, CH 1290 Versoix (Switzerland)

    2013-08-01

    We obtained medium-resolution ultraviolet (UV) spectra between 1150 and 1450 A of the four UV-bright, infrared-luminous starburst galaxies IRAS F08339+6517, NGC 3256, NGC 6090, and NGC 7552 using the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The selected sightlines toward the starburst nuclei probe the properties of the recently formed massive stars and the physical conditions in the starburst-driven galactic superwinds. Despite being metal-rich and dusty, all four galaxies are strong Ly{alpha} emitters with equivalent widths ranging between 2 and 13 A. The UV spectra show strong P Cygni-type high-ionization features indicative of stellar winds and blueshifted low-ionization lines formed in the interstellar and circumgalactic medium. We detect outflowing gas with bulk velocities of {approx}400 km s{sup -1} and maximum velocities of almost 900 km s{sup -1}. These are among the highest values found in the local universe and comparable to outflow velocities found in luminous Lyman-break galaxies at intermediate and high redshift. The outflow velocities are unlikely to be high enough to cause escape of material from the galactic gravitational potential. However, the winds are significant for the evolution of the galaxies by transporting heavy elements from the starburst nuclei and enriching the galaxy halos. The derived mass outflow rates of {approx}100 M{sub Sun} yr{sup -1} are comparable to or even higher than the star formation rates. The outflows can quench star formation and ultimately regulate the starburst as has been suggested for high-redshift galaxies.

  10. Misalignment of Magnetic Fields and Outflows in Protostellar Cores

    OpenAIRE

    Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erica; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.

    2012-01-01

    We present results of λ1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with ~2."5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotati...

  11. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Savage, Blair D.; Wakker, Bart P. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Lockman, Felix J. [National Radio Astronomy Observatory, P.O. Box 2, Rt. 28/92, Green Bank, WV 24944 (United States); Jenkins, Edward B.; Bowen, David V. [Princeton University Observatory, Princeton, NJ 08544 (United States); Bland-Hawthorn, Joss [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Kim, Tae-Sun [Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34143 Trieste (Italy); Benjamin, Robert A., E-mail: afox@stsci.edu [Department of Physics, University of Wisconsin-Whitewater, 800 West Main Street, Whitewater, WI 53190 (United States)

    2015-01-20

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (ℓ, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = –235 and +250 km s{sup –1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ≳900 km s{sup –1} and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  12. Multiday production of condensing organic aerosol mass in urban and forest outflow

    Directory of Open Access Journals (Sweden)

    J. Lee-Taylor

    2014-07-01

    Full Text Available Secondary organic aerosol (SOA production in air masses containing either anthropogenic or biogenic (terpene-dominated emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50% and of shorter duration (1–2 days. The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products of both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.

  13. Powerful quasar outflow in a massive disc galaxy at $z \\sim 5$

    CERN Document Server

    Curtis, Michael

    2016-01-01

    There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to $\\sim 10^9 M_\\odot$ by $z \\sim 5$ and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in previous work using the same feedback strength, and that this leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations...

  14. The Low Energy Neutral Imager (LENI)

    Science.gov (United States)

    Westlake, J. H.; Mitchell, D. G.; Clark, G. B.; Brandt, P. C.; Hoffer, E.

    2016-12-01

    To achieve breakthroughs in the areas of heliospheric and magnetospheric energetic neutral atom (ENA) imaging a new class of instruments is required. We present a high angular resolution ENA imager concept aimed at the suprathermal plasma populations with energies between 0.5 and 20 keV. This instrument is intended for high-spatial resolution ENA imaging of suprathermal plasmas. This technique could be used to understand the spatial and temporal structure of the heliospheric boundary recently revealed by Interstellar Boundary Explorer (IBEX) instrumentation and the Cassini Ion and Neutral Camera (INCA). The instrument is also well suited to characterize magnetospheric ENA emissions from low-altitude ENAs produced by precipitation of magnetospheric ions into the terrestrial upper atmosphere, or from energetic tails of ion outflow, or from the magnetosheath where solar wind protons are neutralized by charge exchange, or from the ring-current region. We present a new technique utilizing ultra-thin carbon foils, 2D collimation using a curved microchannel plate, and a novel electron optical design to produce high-angular resolution (≤2°) and high-sensitivity (≥ 10-3 cm2 sr/pixel) ENA imaging in the 0.5-20 keV energy range.

  15. Flow splitting in numerical simulations of oceanic dense-water outflows

    Science.gov (United States)

    Marques, Gustavo M.; Wells, Mathew G.; Padman, Laurie; Özgökmen, Tamay M.

    2017-05-01

    Flow splitting occurs when part of a gravity current becomes neutrally buoyant and separates from the bottom-trapped plume as an interflow. This phenomenon has been previously observed in laboratory experiments, small-scale water bodies (e.g., lakes) and numerical studies of small-scale systems. Here, the potential for flow splitting in oceanic gravity currents is investigated using high-resolution (Δx = Δz = 5 m) two-dimensional numerical simulations of gravity flows into linearly stratified environments. The model is configured to solve the non-hydrostatic Boussinesq equations without rotation. A set of experiments is conducted by varying the initial buoyancy number B0 =Q0N3 /g‧2 (where Q0 is the volume flux of the dense water flow per unit width, N is the ambient stratification and g‧ is the reduced gravity), the bottom slope (α) and the turbulent Prandtl number (Pr). Regardless of α or Pr, when B0 ≤ 0.002 the outflow always reaches the deep ocean forming an underflow. Similarly, when B0 ≥ 0.13 the outflow always equilibrates at intermediate depths, forming an interflow. However, when B0 ∼ 0.016, flow splitting always occurs when Pr ≥ 10, while interflows always occur for Pr = 1. An important characteristic of simulations that result in flow splitting is the development of Holmboe-like interfacial instabilities and flow transition from a supercritical condition, where the Froude number (Fr) is greater than one, to a slower and more uniform subcritical condition (Fr internal hydraulic jump and consequent mixing enhancement. Although our experiments do not take into account three-dimensionality and rotation, which are likely to influence mixing and the transition between flow regimes, a comparison between our results and oceanic observations suggests that flow splitting may occur in dense-water outflows with weak ambient stratification, such as Antarctic outflows.

  16. SHIELD: Neutral Gas Kinematics and Dynamics

    CERN Document Server

    McNichols, Andrew T; Nims, Elise; Cannon, John M; Adams, Elizabeth A K; Bernstein-Cooper, Elijah Z; Giovanelli, Riccardo; Haynes, Martha P; Józsa, Gyula I G; McQuinn, Kristen B W; Salzer, John J; Skillman, Evan D; Warren, Steven R; Dolphin, Andrew; Elson, E C; Haurberg, Nathalie; Ott, Jürgen; Saintonge, Amelie; Cave, Ian; Hagen, Cedric; Huang, Shan; Janowiecki, Steven; Marshall, Melissa V; Thomann, Clara M; Van Sistine, Angela

    2016-01-01

    We present kinematic analyses of the 12 galaxies in the "Survey of HI in Extremely Low-mass Dwarfs" (SHIELD). We use multi-configuration interferometric observations of the HI 21cm emission line from the Karl G. Jansky Very Large Array (VLA) to produce image cubes at a variety of spatial and spectral resolutions. Both two- and three-dimensional fitting techniques are employed in an attempt to derive inclination-corrected rotation curves for each galaxy. In most cases, the comparable magnitudes of velocity dispersion and projected rotation result in degeneracies that prohibit unambiguous circular velocity solutions. We thus make spatially resolved position-velocity cuts, corrected for inclination using the stellar components, to estimate the circular rotation velocities. We find circular velocities <30 km/s for the entire survey population. Baryonic masses are calculated using single-dish HI fluxes from Arecibo and stellar masses derived from HST and Spitzer imaging. Comparison is made with total dynamical ...

  17. MHOs toward HMOs: A Search for Molecular Hydrogen Emission-Line Objects toward High-mass Outflows

    Science.gov (United States)

    Wolf-Chase, Grace; Arvidsson, Kim; Smutko, Michael

    2017-07-01

    We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H2 2.12 μm/H2 2.25 μm flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ˜1.5-3, while the vast majority of MHOs display flux ratios typical of C-type shocks (˜6-20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (˜3-4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.

  18. Deterministic nanoassembly: Neutral or plasma route?

    Science.gov (United States)

    Levchenko, I.; Ostrikov, K.; Keidar, M.; Xu, S.

    2006-07-01

    It is shown that, owing to selective delivery of ionic and neutral building blocks directly from the ionized gas phase and via surface migration, plasma environments offer a better deal of deterministic synthesis of ordered nanoassemblies compared to thermal chemical vapor deposition. The results of hybrid Monte Carlo (gas phase) and adatom self-organization (surface) simulation suggest that higher aspect ratios and better size and pattern uniformity of carbon nanotip microemitters can be achieved via the plasma route.

  19. Revealing the ultrafast outflow in IRAS 13224-3809 through spectral variability

    Science.gov (United States)

    Parker, M. L.; Alston, W. N.; Buisson, D. J. K.; Fabian, A. C.; Jiang, J.; Kara, E.; Lohfink, A.; Pinto, C.; Reynolds, C. S.

    2017-08-01

    We present an analysis of the long-term X-ray variability of the extreme narrow-line Seyfert 1 galaxy IRAS 13224-3809 using principal component analysis (PCA) and fractional excess variability (Fvar) spectra to identify model-independent spectral components. We identify a series of variability peaks in both the first PCA component and Fvar spectrum which correspond to the strongest predicted absorption lines from the ultrafast outflow (UFO) discovered by Parker et al. (2017). We also find higher order PCA components, which correspond to variability of the soft excess and reflection features. The subtle differences between RMS and PCA results argue that the observed flux-dependence of the absorption is due to increased ionization of the gas, rather than changes in column density or covering fraction. This result demonstrates that we can detect outflows from variability alone and that variability studies of UFOs are an extremely promising avenue for future research.

  20. Probing the photoionised outflow in the NLS1 Ark 564: An XMM-Newton view

    CERN Document Server

    Khanna, Shourya; Mehdipour, Missagh

    2016-01-01

    We present a detailed analysis of xmm X-ray observations of the Narrow line Seyfert-1 (NLS1) galaxy Ark 564 taken between 2000 and 2011. High-resolution X-ray spectroscopy is carried out on the resultant high signal-to-noise stacked spectrum. We find three separate photoionised warm absorbers outflowing at velocities unusually lower than typical NLS1s. Using recombination timescale estimates, improved constraints on the location of these clouds show they could be located beyond 4 pc from the central source. Our estimates of the outflow kinetics suggest that the AGN in Ark 564 is unlikely to affect the host galaxy in its current state but over typical lifetime of 10^7 years the ISM could be affected. The individual observations used here suggest the luminosity varies over weekly timescales and in addition we find evidence of gas response to changes in the ionising radiation.

  1. NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    Kacprzak, Glenn G.; Cooke, Jeff [Swinburne University of Technology, Victoria 3122 (Australia); Martin, Crystal L.; Ho, Stephanie H. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane [CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP) de Toulouse, 14 Avenue E. Belin, F-31400 Toulouse (France); Churchill, Christopher W.; Klimek, Elizabeth, E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  2. Binary stellar mergers with marginally bound ejecta: excretion discs, inflated envelopes, outflows, and their luminous transients

    Science.gov (United States)

    Pejcha, Ondřej; Metzger, Brian D.; Tomida, Kengo

    2016-09-01

    We study mass-loss from the outer Lagrange point (L2) in binary stellar mergers and their luminous transients by means of radiative hydrodynamical simulations. Previously, we showed that for binary mass ratios 0.06 ≲ q ≲ 0.8, synchronous L2 mass-loss results in a radiatively inefficient, dust-forming unbound equatorial outflow. A similar outflow exists irrespective of q if the ratio of the sound speed to the orbital speed at the injection point is sufficiently large, ε ≡ cT/vorb ≳ 0.15. By contrast, for cold L2 mass-loss (ε ≲ 0.15) from binaries with q ≲ 0.06 or q ≳ 0.8, the equatorial outflow instead remains marginally bound and falls back to the binary over tens to hundreds of binary orbits, where it experiences additional tidal torquing and shocking. As the bound gas becomes virialized with the binary, the luminosity of the system increases slowly at approximately constant photosphere radius, causing the temperature to rise. Subsequent evolution depends on the efficiency of radiative cooling. If the bound atmosphere is able to cool efficiently, as quantified by radiative diffusion time being shorter than the advection time (tdiff/tadv ≪ 1), then the virialized gas collapses to an excretion disc, while for tdiff/tadv ≳ 1 an isotropic wind is formed. Between these two extremes, an inflated envelope transports the heat generated near the binary to the surface by meridional flows. In all cases, the radiated luminosity reaches a fraction ˜10-2 to 10-1 of dot{M}v_orb^2/2, where dot{M} is the mass outflow rate. We discuss the implications of our results for transients in the luminosity gap between classical novae and supernovae, such as V1309 Sco and V838 Mon.

  3. Outflow Detection in a 70 μm Dark High-Mass Core

    Science.gov (United States)

    Feng, Siyi; Beuther, Henrik; Zhang, Qizhou; Liu, Hauyu Baobab; Zhang, Zhiyu; Wang, Ke; Qiu, Keping

    2016-09-01

    We present observations toward a high-mass (\\gt 40 {M}⊙ ), low-luminosity (\\lt 10 {L}⊙ ) 70 μ {{m}} dark molecular core G28.34 S-A at 3.4 mm, using the IRAM 30 m telescope and the NOEMA interferometer. We report the detection of {SiO} J=2\\to 1 line emission, which is spatially resolved in this source at a linear resolution of ˜0.1 pc, while the 3.4 mm continuum image does not resolve any internal sub-structures. The SiO emission exhibits two W-E oriented lobes centering on the continuum peak. Corresponding to the redshifted and blueshifted gas with velocities up to 40 {km} {{{s}}}-1 relative to the quiescent cloud, these lobes clearly indicate the presence of a strong bipolar outflow from this 70 μ {{m}} dark core, a source previously considered as one of the best candidates of “starless” core. Our SiO detection is consistent with ALMA archival data of {SiO} J=5\\to 4, whose high-velocity blueshifted gas reveals a more compact lobe spatially closer to the dust center. This outflow indicates that the central source may be in an early evolutionary stage of forming a high-mass protostar. We also find that the low-velocity components (in the range of {{Vlsr}}-5+3 {km} {{{s}}}-1) have an extended, NW-SE oriented distribution. Discussing the possible accretion scenarios of the outflow-powering young stellar object, we argue that molecular line emission and the molecular outflows may provide a better indication of the accretion history of the forming young stellar object, than snapshot observations of the present bolometric luminosity. This is particularly significant for cases of episodic accretion, which may occur during the collapse of the parent molecular core.

  4. Measurement of Outflow Facility Using iPerfusion.

    Directory of Open Access Journals (Sweden)

    Joseph M Sherwood

    Full Text Available Elevated intraocular pressure (IOP is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied

  5. A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Preplanetary Nebula IRAS 22036+5306

    Science.gov (United States)

    Sahai, Raghvendra; Young, K.; Patel, N. A.; Sanchez Contreras, C.; Morris, M.

    2006-01-01

    We report high angular resolution (approx.1") CO J=3-2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (approx.10") CO and 13CO J=1-0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J=3-2 observations show the presence of a very fast (approx.220 km/s), highly collimated, massive (0.03 Solar Mass) bipolar outflow with a very large scalar momentum (about 10(exp 39) g cm/s), and the characteristic spatiokinematic structure of bow shocks at the tips of this outflow. The H(alpha) line shows an absorption feature blueshifted from the systemic velocity by approx.100 km/s, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I22036, as in most PPNs, cannot be driven by radiation pressure. We find an unresolved source of submillimeter (and millimeter-wave) continuum emission in I22036, implying a very substantial mass (0.02-0.04 Solar Mass) of large (radius > or approx.1 mm), cold ( or approx.4 Solar Mass) progenitor in which hot-bottom-burning has occurred.

  6. Neutralization of English Consonants

    Institute of Scientific and Technical Information of China (English)

    庞彬彬

    2011-01-01

    This paper gives a brief account of English consonant cluster's structure and phonetic features from the perspective of the definition and cause of neutralization of English consonants as well as their distinctive features and oppositions.It comes up with the final conclusion that neutralization exists in only thirteen English consonant clusters,among a large number of consonant clusters.

  7. Jet acceleration of the fast molecular outflows in the Seyfert galaxy IC5063

    CERN Document Server

    Tadhunter, C; Rose, M; Oonk, J B R; Oosterloo, T

    2014-01-01

    Massive outflows driven by active galactic nuclei (AGN) are widely recognised to play a key role in the evolution of galaxies, heating the ambient gas, expelling it from the nuclear regions, and thereby affecting the star formation histories of the galaxy bulges. It has been proposed that the powerful jets of relativistic particles launched by some AGN can both accelerate and heat the molecular gas, which often dominates the mass budgets of the outflows. However, clear evidence for this mechanism in the form of detailed associations between the molecular gas kinematics and features in the radio-emitting jets has been lacking. Here we show that the warm molecular hydrogen gas in the western radio lobe of the Seyfert galaxy IC5063 is moving at high velocities - up to 600 km/s - relative to the galaxy disk. This suggests that the molecules have been accelerated by fast shocks driven into the interstellar medium (ISM) by the expanding radio jets. These results demonstrate the general feasibility of accelerating m...

  8. Radiation Pressure Confinement -- III. The origin of the broad ionization distribution in AGN outflows

    CERN Document Server

    Stern, Jonathan; Laor, Ari; Baskin, Alexei; Holczer, Tomer

    2014-01-01

    The winds of ionized gas driven by Active Galactic Nuclei (AGN) can be studied through absorption features in their X-ray spectra. A recurring feature of these outflows is their broad ionization distribution, including essentially all ionization levels (e.g., Fe^0+ to Fe^25+). The absorption measure distribution (AMD) is defined as the distribution of column density with ionization parameter |dN / dlog xi|. The AMD extends over a wide range of 0.1 < xi < 10^4 (cgs), and is remarkably similar in different objects. Power-law fits to the observed AMDs (|dN / dlog xi| ~ N_1 xi^a) yield N_1 = 3x10^21 cm^-2 +- 0.4 dex and a = 0 -- 0.4. What is the source of this broad ionization distribution, and what sets the small range of observed $N_1$ and $a$ values? A common interpretation is a multiphase outflow, with a wide range of gas densities in a uniform pressure medium. However, it has already been shown that the incident radiation pressure leads to a gas pressure gradient in the photoionized gas, and therefore ...

  9. Outflows Driven by Quasars in High-Redshift Galaxies with Radiation Hydrodynamics

    CERN Document Server

    Bieri, Rebekka; Rosdahl, Joakim; Wagner, Alexander Y; Silk, Joseph; Mamon, Gary A

    2016-01-01

    The quasar mode of Active Galactic Nuclei (AGN) in the high-redshift Universe is routinely observed in gas-rich galaxies together with large-scale AGN-driven winds. It is crucial to understand how photons emitted by the central AGN source couple to the ambient interstellar-medium to trigger large-scale outflows. By means of radiation-hydrodynamical simulations of idealised galactic discs, we study the coupling of photons with the multiphase galactic gas, and how it varies with gas cloud sizes, and the radiation bands included in the simulations, which are ultraviolet (UV), optical, and infrared (IR). We show how a quasar with a luminosity of $10^{46}$ erg/s can drive large-scale winds with velocities of $10^2-10^3$ km/s and mass outflow rates around $10^3$ M$_\\odot$/yr for times of order a few million years. Infrared radiation is necessary to efficiently transfer momentum to the gas via multi-scattering on dust in dense clouds. However, IR multi-scattering, despite being extremely important at early times, qu...

  10. Grain Evolution across the Shocks in the L1448-mm Outflow

    CERN Document Server

    Jimenez-Serra, I; Rodríguez-Franco, A; Martin, S

    2005-01-01

    The recent detection of shock-precursors toward the very young L1448-mm outflow offers us the possibility to study the grain chemistry during the first stages of the shock evolution, constraining the molecules ejected from grains and the species formed in gas phase. Observations of key molecules in the grain chemistry such as SiO, CH3OH, SO, CS, H2S, OCS, and SO2 toward this outflow are presented. The line profiles and the derived abundances show three distinct velocity regimes that trace the shock evolution: the preshock, the shock-precursor and the postshock gas. The SiO, CH3OH, SO, and CS abundances are enhanced with respect to the quiescent gas by 1 order of magnitude in the shock-precursor component, and by 3 orders of magnitude in the postshock gas. The derived SiO and CH3OH abundances are consistent with the recent ejection of these molecules from grains. Since H2S is only enhanced in the shock-precursor component, and OCS and SO2 are undetected, SO and CS are the most abundant sulfur-bearing species i...

  11. Collective outflow from a small multiple stellar system

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Thomas [Institut für Theoretische Physik, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Klaassen, Pamela D. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Mac Low, Mordecai-Mark [Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024-5192 (United States); Schrön, Martin; Klessen, Ralf S. [Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Federrath, Christoph [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Vic 3800 (Australia); Smith, Michael D., E-mail: tpeters@physik.uzh.ch [Centre for Astrophysics and Space Science, University of Kent, Canterbury, CT2 7NH (United Kingdom)

    2014-06-10

    The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M {sub ☉}, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H{sub 2} and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of two to three.

  12. Standing Shocks around Black Holes and Estimation of Outflow Rates

    Indian Academy of Sciences (India)

    Santabrata Das; Sandip K. Chakrabarti

    2002-03-01

    We self-consistently obtain shock locations in an accretion flow by using an analytical method. One can obtain the spectral properties, quasi-periodic oscillation frequencies and the outflowrates when the inflow parameters are known. Since temperature of the CENBOL decides the spectral states of the black hole, and also the outflow rate, the outflow rate is directly related to the spectral states.

  13. An Intergalactic Magnetic Field from Quasar Outflows

    CERN Document Server

    Furlanetto, S; Furlanetto, Steven; Loeb, Abraham

    2001-01-01

    Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and calculate their distribution as a function magnetic field strength at different redshifts. We find that by a redshift z ~ 3, about 5-80% of the IGM volume is filled by magnetic fields with an energy density > 10% of the mean thermal energy density of a photo-ionized IGM (at ~ 10^4 K). As massive galaxies and X-ray clusters condense out of the magnetized IGM, the adiabatic compression of the magnetic field could result in the fields observed in these systems without a need for further dynamo amplification.

  14. Relativistic Outflows in Gamma-Ray Bursts

    CERN Document Server

    Aloy, M A

    2007-01-01

    The possibility that gamma-ray bursts (GRBs) were not isotropic emissions was devised theoretically as a way to ameliorate the huge energetic budget implied by the standard fireball model for these powerful phenomena. However, the mechanism by which after the quasy-isotropic release of a few $10^{50} $erg yields a collimated ejection of plasma could not be satisfactory explained analytically. The reason being that the collimation of an outflow by its progenitor system depends on a very complex and non-linear dynamics. That has made necessary the use of numerical simulations in order to shed some light on the viability of some likely progenitors of GRBs. In this contribution I will review the most relevant features shown by these numerical simulations and how they have been used to validate the collapsar model (for long GRBs) and the model involving the merger of compact binaries (for short GRBs).

  15. Ice sculpture in the Martian outflow channels

    Science.gov (United States)

    Lucchitta, B. K.

    1982-01-01

    Viking Orbiter and terrestrial satellite images are examined at similar resolution to compare features of the Martian outflow channels with features produced by the movement of ice on earth, and many resemblances are found. These include the anastomoses, sinuosities, and U-shaped cross profiles of valleys; hanging valleys; linear scour marks on valley walls; grooves and ridges on valley floors; and the streamlining of bedrock highs. Attention is given to the question whether ice could have moved in the Martian environment. It is envisaged that springs or small catastrophic outbursts discharged fluids from structural outlets or chaotic terrains. These fluids built icings that may have grown into substantial masses and eventually flowed like glaciers down preexisting valleys. An alternative is that the fluids formed rivers or floods that in turn formed ice jams and consolidated into icy masses in places where obstacles blocked their flow.

  16. Searching for molecular outflows in Hyper-Luminous Infrared Galaxies

    CERN Document Server

    Calderón, D; Veilleux, S; Graciá-Carpio, J; Sturm, E; Lira, P; Schulze, S; Kim, S

    2016-01-01

    We present constraints on the molecular outflows in a sample of five Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet at 119 {\\mu}m. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ~1500 km/s. Our analysis shows that this system is in general agreement with previous results on Ultra-luminous Infrared Galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead the galaxy outflow likely arises from an embedded AGN.

  17. Reconnection outflow generated turbulence in the solar wind

    CERN Document Server

    Vörös, Z; Semenov, V S; Zaqarashvili, T V; Bruno, R; Khodachenko, M

    2014-01-01

    Petschek-type time-dependent reconnection (TDR) and quasi-stationary reconnection (QSR) models are considered to understand reconnection outflow structures and the features of the associated locally generated turbulence in the solar wind. We show that the outflow structures, such as discontinuites, Kelvin-Helmholtz (KH) unstable flux tubes or continuous space filling flows cannot be distinguished from one-point WIND measurements. In both models the reconnection outflows can generate more or less spatially extended turbulent boundary layers (TBDs). The structure of an unique extended reconnection outflow is investigated in detail. The analysis of spectral scalings and break locations show that reconnection outflows can control the local field and plasma conditions which may play in favor of one or another turbulent dissipation mechanisms with their characteristic scales and wavenumbers.

  18. The Implications of Extreme Outflows from Extreme Starbursts

    CERN Document Server

    Heckman, Timothy M

    2016-01-01

    Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along the extrapolation of, the trends defined by the more typical systems studied previously by us. We exploit the wide dynamic range provided by this new sample to determine scaling relations of outflow velocity with galaxy stellar mass (M*), circular velocity, star-formation rate (SFR), SFR/M*, and SFR/area. We argue that these results can be accommodated within the general interpretational framework we previously advocated, in which a population of ambient interstellar or circum-galactic clouds is accelerated by the combine...

  19. Cosmic-ray Driven Outflows in Global Galaxy Disk Models

    CERN Document Server

    Salem, Munier

    2013-01-01

    Galactic-scale winds are a generic feature of massive galaxies with high star formation rates across a broad range of redshifts. Despite their importance, a detailed physical understanding of what drives these mass-loaded global flows has remained elusive. In this paper, we explore the dynamical impact of cosmic rays by performing the first three-dimensional, adaptive mesh refinement simulations of an isolated starbursting galaxy that includes a basic model for the production, dynamics and diffusion of galactic cosmic rays. We find that including cosmic rays naturally leads to robust, massive, bipolar outflows from our 10^12 Msun halo, with a mass-loading factor Mout/SFR = 0.3 for our fiducial run. Other reasonable parameter choices led to mass-loading factors above unity. The wind is multiphase and is accelerated to velocities well in excess of the escape velocity. We employ a two-fluid model for the thermal gas and relativistic CR plasma and model a range of physics relevant to galaxy formation, including r...

  20. AGN Outflow Shocks on Bonnor-Ebert Spheres

    CERN Document Server

    Dugan, Zachary; Bieri, Rebekka; Silk, Joseph; Rahman, Mubdi

    2016-01-01

    Feedback from Active Galactic Nuclei (AGN) and subsequent jet cocoons and outflow bubbles can have a significant impact on star formation in the host galaxy. To investigate feedback physics on small scales, we perform hydrodynamic simulations of realistically fast AGN winds striking Bonnor-Ebert (BE) spheres and examine gravitational collapse and ablation. We test AGN wind velocities ranging from 300--3,000 km s$^{-1}$ and wind densities ranging from 0.5--10 $m_\\mathrm{p}\\,\\mathrm{cm}^{-3}$. We include heating and cooling of low- and high-temperature gas, self-gravity, and spatially correlated perturbations in the shock, with a maximum resolution of 0.01 pc. We find that the ram pressure is the most important factor that determines the fate of the cloud. High ram pressure winds increase fragmentation and decrease the star formation rate, but also cause star formation to occur on a much shorter time scale and with increased velocities of the newly formed stars. We find a threshold ram pressure of $\\sim 2\\times...