WorldWideScience

Sample records for balmer emission lines

  1. Balmer line shifts in quasars

    CERN Document Server

    Sulentic, J W; Del Olmo, A; Zamfir, S

    2015-01-01

    We offer a broad review of Balmer line phenomenology in type 1 active galactic nuclei, briefly sum- marising luminosity and radio loudness effects, and discussing interpretation in terms of nebular physics along the 4D eigenvector 1 sequence of quasars. We stress that relatively rare, peculiar Balmer line profiles (i.e., with large shifts with respect to the rest frame or double and multiple peaked) that start attracted attentions since the 1970s are still passable of multiple dynamical interpretation. More mainstream objects are still not fully understood as well, since competing dynamical models and geometries are possible. Further progress may come from inter-line comparison across the 4D Eigenvector 1 sequence.

  2. Aperture corrections for disk galaxy properties derived from the CALIFA survey. Balmer emission lines in spiral galaxies

    CERN Document Server

    Iglesias-Páramo, J; Galbany, L; Sánchez, S F; Rosales-Ortega, F F; Mast, D; García-Benito, R; Husemann, B; Aguerri, J A L; Alves, J; Bekeraité, S; Bland-Hawthorn, J; Catalán-Torrecilla, C; de Amorim, A L; de Lorenzo-Cáceres, A; Ellis, S; Falcón-Barroso, J; Flores, H; Florido, E; Gallazzi, A; Gomes, J M; Delgado, R M González; Haines, T; Hernández-Fernández, J D; Kehrig, C; López-Sánchez, A R; Lyubenova, M; Marino, R A; Mollá, M; Monreal-Ibero, A; Mourão, A; Papaderos, P; Sánchez-Blázquez, P; Spekkens, K; Stanishev, V; van de Ven, G; Walcher, C J; Wisotzki, L; Zibetti, S; Ziegler, B

    2013-01-01

    This work investigates the effect of the aperture size on derived galaxy properties for which we have spatially-resolved optical spectra. We focus on some indicators of star formation activity and dust attenuation for spiral galaxies that have been widely used in previous work on galaxy evolution. We have used 104 spiral galaxies from the CALIFA survey for which 2D spectroscopy with complete spatial coverage is available. From the 3D cubes we have derived growth curves of the most conspicuous Balmer emission lines (Halpha, Hbeta) for circular apertures of different radii centered at the galaxy's nucleus after removing the underlying stellar continuum. We find that the Halpha flux (f(Halpha)) growth curve follows a well defined sequence with aperture radius showing low dispersion around the median value. From this analysis, we derive aperture corrections for galaxies in different magnitude and redshift intervals. Once stellar absorption is properly accounted for, the f(Halpha)/f(Hbeta) ratio growth curve shows...

  3. Discovery of superstrong, fading, iron line emission and double-peaked Balmer lines of the galaxy SDSSJ0952+2143 - the light echo of a huge flare

    CERN Document Server

    Komossa, S; Wang, T; Ajello, M; Ge, J; Greiner, J; Lü, H; Salvato, M; Saxton, R; Shan, H; Xu, D; Yuan, W

    2008-01-01

    We report the discovery of superstrong, fading, high-ionization iron line emission in the galaxy SDSSJ095209.56+214313.3 (SDSSJ0952+2143 hereafter), which must have been caused by an X-ray outburst of large amplitude. SDSSJ0952+2143 is unique in its strong multiwavelength variability; such a broadband emission-line and continuum response has not been observed before. The strong iron line emission is accompanied by unusual Balmer line emission with a broad base, narrow core and double-peaked narrow horns, and strong HeII emission. These lines, while strong in the SDSS spectrum taken in 2005, have faded away significantly in new spectra taken in December 2007. Comparison of SDSS, 2MASS, GALEX and follow-up GROND photometry reveals variability in the NUV, optical and NIR band. Taken together, these unusual observations can be explained by a giant outburst in the EUV--X-ray band, detected even in the optical and NIR. The intense and variable iron, Helium and Balmer lines represent the ``light echo'' of the flare,...

  4. Solar prominences with Na and Mg emissions and centrally reversed Balmer line

    CERN Document Server

    Stellmacher, G; 10.1051/0004-6361:20041550

    2012-01-01

    We study spectral lines in exceptionally bright solar limb prominences with pronounced sodium and magnesium emission. We find that most prominences with significant NaD2 and Mgb2 emission show centrally reversed profiles of H-alpha and occasionally even of H-beta, which are are well reproduced by semi-infinite models. The maximum H-alpha source function corresponds to an excitation temperature of 3950 K, for pronounced central reversions 4000 K; the related optical thickness exceeds 10.0. The narrow widths of the NaD2 and Mgb2 profiles yield a non-thermal broadening of 5 km/s.

  5. Collisionless shock in a partially ionized medium. II. Balmer emission

    CERN Document Server

    Morlino, G; Blasi, P; Amato, E

    2012-01-01

    Strong shocks propagating into a partially ionized medium are often associated with optical Balmer lines. This emission is due to impact excitation of neutral hydrogen by hot protons and electrons in the shocked gas. The structure of such Balmer-dominated shocks has been computed in a previous paper (Blasi et al. 2012), where the distribution function of neutral particles was derived from the appropriate Boltzmann equation including coupling with ions and electrons through charge exchange and ionization. This calculation showed how the presence of neutrals can significantly modify the shock structure through the formation of a "neutral-induced" precursor ahead of the shock. Here we follow up on our previous work and investigate the properties of the resulting Balmer emission, with the aim of using the observed radiation as a diagnostic tool for shock parameters. Our main focus is on Supernova Remnant shocks, and we find that, for typical parameters, the H{\\alpha} emission typically has a three-component spect...

  6. COLLISIONLESS SHOCKS IN A PARTIALLY IONIZED MEDIUM. II. BALMER EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Morlino, G.; Bandiera, R.; Blasi, P.; Amato, E. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)

    2012-12-01

    Strong shocks propagating into a partially ionized medium are often associated with optical Balmer lines. This emission is due to impact excitation of neutral hydrogen by hot protons and electrons in the shocked gas. The structure of such Balmer-dominated shocks has been computed in a previous paper, where the distribution function of neutral particles was derived from the appropriate Boltzmann equation including coupling with ions and electrons through charge exchange and ionization. This calculation showed how the presence of neutrals can significantly modify the shock structure through the formation of a neutral-induced precursor ahead of the shock. Here we follow up on our previous work and investigate the properties of the resulting Balmer emission, with the aim of using the observed radiation as a diagnostic tool for shock parameters. Our main focus is on supernova remnant shocks, and we find that, for typical parameters, the H{alpha} emission typically has a three-component spectral profile, where (1) a narrow component originates from upstream cold hydrogen atoms, (2) a broad component comes from hydrogen atoms that have undergone charge exchange with shocked protons downstream of the shock, and (3) an intermediate component is due to hydrogen atoms that have undergone charge exchange with warm protons in the neutral-induced precursor. The relative importance of these three components depends on the shock velocity, on the original degree of ionization, and on the electron-ion temperature equilibration level. The intermediate component, which is the main signature of the presence of a neutral-induced precursor, becomes negligible for shock velocities {approx}< 1500 km s{sup -1}. The width of the intermediate line reflects the temperature in the precursor, while the width of the narrow one is left unaltered by the precursor. In addition, we show that the profiles of both the intermediate and broad components generally depart from a thermal distribution, as a

  7. Indicators of star formation : 4000 angstrom break and Balmer lines

    NARCIS (Netherlands)

    Poggianti, BM; Barbaro, G

    1997-01-01

    The behaviour of the 4000 Angstrom break index and of the equivalent width of the main Balmer lines is investigated a) for a single star as a function of effective temperature, gravity and metallicity and b) for a single stellar population as a function of age and metallicity. Consequences for the i

  8. Constraining Sub-Parsec Binary Supermassive Black Holes in Quasars with Multi-Epoch Spectroscopy. II. The Population with Kinematically Offset Broad Balmer Emission Lines

    CERN Document Server

    Liu, Xin; Bian, Fuyan; Loeb, Abraham; Tremaine, Scott

    2013-01-01

    A small fraction of quasars have long been known to show bulk velocity offsets in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (~sub-pc) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with offset broad H-beta lines from the SDSS DR7 quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad H-beta lines with a rest-frame baseline of a few years to nearly a decade. Using cross-correlation analysis, we detect significant (99% confidence) radial accelerati...

  9. Constraining sub-parsec binary supermassive black holes in quasars with multi-epoch spectroscopy. II. The population with kinematically offset broad Balmer emission lines

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Bian, Fuyan [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Loeb, Abraham [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tremaine, Scott, E-mail: xinliu@astro.ucla.edu [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2014-07-10

    A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred to thousands of km s{sup –1}) in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (∼sub-parsec (sub-pc)) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with kinematically offset broad Hβ lines from the Sloan Digital Sky Survey (SDSS) Seventh Data Release quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad Hβ lines with a rest-frame baseline of a few years to nearly a decade. While previous work focused on objects with extreme velocity offset (>10{sup 3} km s{sup –1}), we explore the parameter space with smaller (a few hundred km s{sup –1}) yet significant offsets (99.7% confidence). Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad Hβ lines in 24 of the 50 objects, of ∼10-200 km s{sup –1} yr{sup –1} with a median measurement uncertainty of ∼10 km s{sup –1} yr{sup –1}, implying a high fraction of variability of the broad-line velocity on multi-year timescales. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either Hα or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I, we find a tentative anti-correlation between the velocity offset in the

  10. The Peculiar Balmer Line Profiles of OQ 208

    CERN Document Server

    Marziani, P; Calvani, M; Pérez, E; Moles, M; Penston, M V

    1993-01-01

    We present spectrophotometric observations of the Broad Line Radio Galaxy OQ 208 (Mrk 668, 1404+286) obtained between 1985 and 1991. We show that the Balmer line fluxes and profile shapes undergo remarkable changes. The ratio of intensities between the broad and narrow components of Hbeta increased monotonically from 15 in 1985 to 40 in 1991. The peak of the broad components of Hbeta and Halpha were known to be strongly displaced to the red. We have discovered a correlation between the amplitude of the broad peak displacement and the luminosity of Hbeta, in the sense that the displacement is larger when the line luminosity is higher. We suggest that the observations are not compatible with either a binary Broad Line Region model or one involving ballistic acceleration of the line emitting gas. Radiative acceleration of a system of outflowing clouds readily explains the correlation between line shift and luminosity as well as the peculiar line profiles. Furthermore, it seems that most or all of the Balmer emis...

  11. Resolution of the discrepancy between Balmer alpha emission rates, the solar Lyman beta flux, and models of geocoronal hydrogen concentration

    Science.gov (United States)

    Levasseur, A.-C.; Meier, R. R.; Tinsley, B. A.

    1976-01-01

    New satellite Balmer alpha measurements and solar Lyman beta flux and line profile measurements, together with new measurements of the zodiacal light intensity used in correcting both ground and satellite Balmer alpha measurements for the effects of the Fraunhofer line in the zodiacal light, have been used in a reevaluation of the long-standing discrepancy between ground-based Balmer alpha emission rates and other geocoronal hydrogen parameters. The solar Lyman beta line center flux is found to be (4.1 plus or minus 1.3) billion photons per sq cm per sec per angstrom at S(10.7) equals 110 and, together with a current hydrogen model which has 92,000 atoms per cu cm at 650 km for T(inf) equals 950 K, gives good agreement between calculated Balmer alpha emission rates and the ground-based and satellite measurements.

  12. The analysis of the hydrogen broad Balmer line ratios: possible implications to the physical properties of the BLR of AGN

    CERN Document Server

    Ilic, D; La Mura, G; Ciroi, S; Rafanelli, P

    2012-01-01

    We analyze the ratios of the broad hydrogen Balmer emission lines (from H\\alpha to H\\epsilon) in the context of estimating the physical conditions in the broad line region (BLR) of active galactic nuclei (AGN). The Balmer emission lines are obtained in three ways: i) using photoionization models obtained by a spectral synthesis code CLOUDY; ii) calculated using the recombination theory for hydrogenic ions; iii) measured from the sample of observed spectra taken from the Sloan Digital Sky Survey database. We investigate the Balmer line ratios in the frame of the so called Boltzmann-plot (BP), analyzing physical conditions of the emitting plasma for which we could use the BP method. The BP considers the ratio of Balmer lines normalized to the atomic data of the corresponding line transition, and is in that way different from the Balmer decrement. We found that for a certain range of thermodynamic parameters, there are objects that follow the BP. These AGN may have a BLR consisting of mostly high density plasma.

  13. Modelling of passive spectroscopy in the ITER divertor: the first hydrogen Balmer lines

    International Nuclear Information System (INIS)

    The first lines of the hydrogen Balmer series are investigated in ITER divertor conditions using a line shape code and a plasma edge transport code. It is shown that most of the emissivity originates from a localized, cold and dense region close to the divertor target plates, where the plasma is in the recombining regime. We simulate the signal obtained by pointing a spectrometer at this zone. The physical processes which contribute to the spectral line formation are examined, with a special emphasis on the Stark effect, photon absorption and stimulated emission. It is shown that, even though the Stark effect is significant, local information on the Doppler atomic temperature can be obtained from a fitting analysis of the Dα spectral line shape.

  14. Modelling of passive spectroscopy in the ITER divertor: the first hydrogen Balmer lines

    Science.gov (United States)

    Rosato, J.; Kotov, V.; Reiter, D.

    2010-07-01

    The first lines of the hydrogen Balmer series are investigated in ITER divertor conditions using a line shape code and a plasma edge transport code. It is shown that most of the emissivity originates from a localized, cold and dense region close to the divertor target plates, where the plasma is in the recombining regime. We simulate the signal obtained by pointing a spectrometer at this zone. The physical processes which contribute to the spectral line formation are examined, with a special emphasis on the Stark effect, photon absorption and stimulated emission. It is shown that, even though the Stark effect is significant, local information on the Doppler atomic temperature can be obtained from a fitting analysis of the Dα spectral line shape.

  15. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    OpenAIRE

    Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this positio...

  16. Black Hole Mass Estimates Based on CIV are Consistent with Those Based on the Balmer Lines

    CERN Document Server

    Assef, R J; Kochanek, C S; Peterson, B M; Kozlowski, S; Ageorges, N; Buschkamp, P; Falco, E; Feiz, C; Gemperlein, H; Germeroth, A; Grier, C J; Hofmann, R; Juette, M; Khan, R; Kilic, M; Knierim, V; Laun, W; Lederer, R; Lehmitz, M; Lenzen, R; Mall, U; Mandel, H; Martini, P; Mueller, P; Naranjo, V; Pasquali, A; Polsterer, K; Pogge, R W; Quirrenbach, A; Seifert, W; Shappee, B; Storz, C; Van Saders, J; Weiser, P; Zhang, D

    2010-01-01

    Using a sample of high-redshift lensed quasars from the CASTLES project with observed-frame ultraviolet or optical and near-infrared spectra, we have searched for possible biases between supermassive black hole (BH) mass estimates based on the CIV, Halpha and Hbeta broad emission lines. Our sample is based upon that of Greene, Peng & Ludwig, expanded with new near-IR spectroscopic observations, consistently analyzed high S/N optical spectra, and consistent continuum luminosity estimates at 5100A. We find that BH mass estimates based on the FWHM of CIV show a systematic offset with respect to those obtained from the line dispersion, sigma_l, of the same emission line, but not with those obtained from the FWHM of Halpha and Hbeta. The magnitude of the offset depends on the treatment of the HeII and FeII emission blended with CIV, but there is little scatter for any fixed measurement prescription. While we otherwise find no systematic offsets between CIV and Balmer line mass estimates, we do find that the re...

  17. A possible solution to the Lyman/Balmer line problem in hot DA white dwarfs

    CERN Document Server

    Preval, S P; Badnell, N R; Holberg, J B; Hubeny, I

    2014-01-01

    Arguably, the best method for determining the effective temperature ($T_{\\mathrm{eff}}$) and surface gravity (log $g$) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with $T_{\\mathrm{eff}}$>50,000K, the calculated value from the Lyman and Balmer lines are discrepant, which worsens with increasing temperature. Many different solutions have been suggested, ranging from the input physics used to calculate the models, to interstellar reddening. We will focus on the former, and consider three variables. The first is the atomic data used, namely the number of transitions included in line blanketing treatments and the photoionization cross sections. The second is the stark broadening treatment used to synthesise the Lyman and Balmer line profiles, namely the calculations performed by Lemke (1997) and Tremblay & Bergeron (2009). Finally, the third is the atmospheric content. The model grids are calculated with a pure H composition, ...

  18. Are broad optical balmer lines from central accretion disk in PG 1613+658?

    CERN Document Server

    Zhang, XueGuang

    2014-01-01

    In this letter, we report positive correlations between broad line width and broad line flux for the broad balmer lines of the long-term observed AGN PG 1613+658. Rather than the expected negative correlations under the widely accepted virialization assumption for AGN BLRs, the positive correlations indicate much different BLR structures of PG 1613+658 from the commonly considered BLR structures which are dominated by the equilibrium between radiation pressure and gas pressure. Therefore, accretion disk origin is preferred for the observed broad single-peaked optical balmer lines of PG 1613+658, because of the mainly gravity dominated disk-like BLRs with radial structures having few effects from radiation pressure.

  19. Variation in the pre-transit Balmer line signal around the hot Jupiter HD 189733 b

    CERN Document Server

    Cauley, P Wilson; Jensen, Adam G; Barman, Travis

    2016-01-01

    As followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full pre-transit phase coverage of a single planetary transit. The pre-transit signal is again detected in the Balmer lines but with variable strength and timing, suggesting that the bow shock geometry reported in our previous work does not describe the signal from the latest transit. We also demonstrate the use of the Ca II H and K residual core flux as a proxy for the stellar activity level throughout the transit. A moderate trend is found between the pre-transit absorption signal in the 2013 data and the Ca II H flux. This suggests that some of the 2013 pre-transit hydrogen absorption can be attributed to varying stellar activity levels. A very weak correlation is found between the Ca II H core flux and the Balmer line absorption in the 2015 transit, hinting at a smaller contribution from stellar activity compared to the 2013 transit. We simulate how varying stellar activity levels can produce changes in the Balmer ...

  20. Variation in the Pre-transit Balmer Line Signal Around the Hot Jupiter HD 189733b

    Science.gov (United States)

    Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.; Barman, Travis

    2016-07-01

    As followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full pre-transit phase coverage of a single planetary transit. The pre-transit signal is again detected in the Balmer lines but with variable strength and timing, suggesting that the bow shock geometry reported in our previous work does not describe the signal from the latest transit. We also demonstrate the use of the Ca ii H and K residual core flux as a proxy for the stellar activity level throughout the transit. A moderate trend is found between the pre-transit absorption signal in the 2013 data and the Ca ii H flux. This suggests that some of the 2013 pre-transit hydrogen absorption can be attributed to varying stellar activity levels. A very weak correlation is found between the Ca ii H core flux and the Balmer line absorption in the 2015 transit, hinting at a smaller contribution from stellar activity compared to the 2013 transit. We simulate how varying stellar activity levels can produce changes in the Balmer line transmission spectra. These simulations show that the strength of the 2013 and 2015 pre-transit signals can be reproduced by stellar variability. If the pre-transit signature is attributed to circumplanetary material, its evolution in time can be described by accretion clumps spiraling toward the star, although this interpretation has serious limitations. Further high-cadence monitoring at Hα is necessary to distinguish between true absorption by transiting material and short-term variations in the stellar activity level.

  1. Evaluation of hydrogen atom density in the plasma core region based on the Balmerline profile

    Science.gov (United States)

    Goto, M.; Sawada, K.; Fujii, K.; Hasuo, M.; Morita, S.

    2011-02-01

    The Balmerline profile is measured with high wavelength resolution for a discharge in the Large Helical Device. The line profile is regarded as a superposition of continuously varying Doppler broadened components and is expressed as the Laplace transform. Numerical Laplace inversion of the measured line profile gives the distribution function of line emissivity in terms of atom temperature. The temperature dependence of the line emissivity is interpreted as spatial dependence so that the ionization rate and atom density of neutral hydrogen are determined. The temperature range of the detected atoms extends beyond 2 keV which corresponds to a penetration depth of about 1 m in the plasma, or the location at ρ ~ 0.3, where ρ is the normalized minor radius. The atom density of approximately 1013 m-3 is derived in the plasma core region which is more than four orders smaller than that at the plasma boundary. Calculation of neutral transport with a Monte-Carlo simulation code gives satisfactory consistency with the experimental results.

  2. Evaluation of hydrogen atom density in the plasma core region based on the Balmerline profile

    International Nuclear Information System (INIS)

    The Balmerline profile is measured with high wavelength resolution for a discharge in the Large Helical Device. The line profile is regarded as a superposition of continuously varying Doppler broadened components and is expressed as the Laplace transform. Numerical Laplace inversion of the measured line profile gives the distribution function of line emissivity in terms of atom temperature. The temperature dependence of the line emissivity is interpreted as spatial dependence so that the ionization rate and atom density of neutral hydrogen are determined. The temperature range of the detected atoms extends beyond 2 keV which corresponds to a penetration depth of about 1 m in the plasma, or the location at ρ ∼ 0.3, where ρ is the normalized minor radius. The atom density of approximately 1013 m-3 is derived in the plasma core region which is more than four orders smaller than that at the plasma boundary. Calculation of neutral transport with a Monte-Carlo simulation code gives satisfactory consistency with the experimental results.

  3. Variations of the high-level Balmer line spectrum of the helium-strong star Sigma Orionis E

    CERN Document Server

    Smith, Myron A

    2007-01-01

    Using the high-level Balmer lines and continuum, we trace the density structure of two magnetospheric disk segments of the prototypical Bp star sigma Ori E (B2p) as these segments occult portions of the star during the rotational cycle. High-resolution spectra of the Balmer lines >H9 and Balmer edge were obtained on seven nights in January-February 2007 at an average sampling of 0.01 cycles. We measured equivalent width variations due to the star occultations by two disk segments 0.4 cycles apart and constructed differential spectra of the migrations of the corresponding absorptions across the Balmer line profiles. We first estimated the rotational and magnetic obliquity angles. We then simulated the observed Balmer jump variation using the model atmosphere codes synspec/circus and evaluated the disk geometry and gas thermodynamics. We find that the two occultations are caused by two disk segments. The first of these transits quickly, indicating that the segment resides in a range of distances, perhaps 2.5-6R...

  4. Translational spectroscopy of electron impact dissociation of HF by Doppler profile measurements of Balmeremission

    International Nuclear Information System (INIS)

    The Doppler profiles of the Balmeremission by electron impact on HF have been investigated through varying the electron impact energy by using an etalon-grating monochromator with a high resolving power. The spectral profiles of the Balmeremission consist of three components, which indicates that there are three kinds of precursors leading to Hsup(*)(3) contributing to the Balmeremission. The average kinetic energy of Hsup(*)(3) is obtained for each component. From discussions on the precursors of Hsup(*)(3) and their dissociation processes, the observed profiles have been ascribed to the dissociation of Rydberg states (approx. equal to18 eV), doubly excited states (approx. equal to23 eV) and inner shell excited states (approx. equal to40 eV). (orig.)

  5. Optimization of C5+ Balmer- line intensity at 182 Å from laser-produced carbon plasma

    Indian Academy of Sciences (India)

    A Chowdhury; R A Joshi; P A Naik; P D Gupta

    2007-01-01

    Parametric dependence of the intensity of 182 Å Balmer- line (C5+; = 3 → 2), relevant to xuv soft X-ray lasing schemes, from laser-produced carbon plasma is studied in circular spot focusing geometry using a flat field grating spectrograph. The maximum spectral intensity for this line in space integrated mode occurred at a laser intensity of 1.2 × 1013 W cm-2. At this laser intensity, the space resolved measurements show that the spectral intensity of this line peaks at ∼ 1.5 mm from the target surface indicating the maximum population of C5+ ions ( = 3), at this distance. From a comparison of spatial intensity variation of this line with that of C5+ Ly- ( = 2 → 1) line, it is inferred that = 3 state of C5+ ions is predominantly populated through three-body recombination pumping of C6+ ions of the expanding plasma consistent with quantitative estimates on recombination rates of different processes.

  6. On the determination of plasma electron number density from Stark broadened hydrogen Balmer series lines in Laser-Induced Breakdown Spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pardini, L., E-mail: loren.pard@gmail.com [Istituto di Chimica dei Composti Organometallici del CNR, Area della Ricerca del CNR di Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Legnaioli, S.; Lorenzetti, G.; Palleschi, V. [Istituto di Chimica dei Composti Organometallici del CNR, Area della Ricerca del CNR di Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Gaudiuso, R.; De Giacomo, A. [Dipartimento di Chimica, Università di Bari, Via Orabona 4, 70126 Bari (Italy); Diaz Pace, D.M. [Instituto de Física ‘Arroyo Seco’, Facultad de Ciencias Exactas, Paraje Arroyo Seco, B7000GHG Tandil (Argentina); Anabitarte Garcia, F. [Photonic Engineering Group, Universidad de Cantabria, Edificio I+D+iTelecomunicación, Dpto. TEISA, 39005 Santander (Spain); Holanda Cavalcanti, G. de [Institute of Physics, Universidade Federal Fluminense, UFF, Campus da Praia Vermelha, Av. Gal Milton Tavares de Souza, Gragoatá, 24310 240 Niterói, RJ (Brazil); Parigger, C. [University of Tennessee Space Institute, 411 B. H. Goethert Parkway, Tullahoma, TN 37388-9700 (United States)

    2013-10-01

    In this work, different theories for the determination of the electron density in Laser-Induced Breakdown Spectroscopy (LIBS) utilizing the emission lines belonging to the hydrogen Balmer series have been investigated. The plasmas were generated by a Nd:Yag laser (1064 nm) pulsed irradiation of pure hydrogen gas at a pressure of 2 · 10{sup 4} Pa. H{sub α}, Η{sub β}, Η{sub γ}, Η{sub δ}, and H{sub ε} Balmer lines were recorded at different delay times after the laser pulse. The plasma electron density was evaluated through the measurement of the Stark broadenings and the experimental results were compared with the predictions of three theories (the Standard Theory as developed by Kepple and Griem, the Advanced Generalized Theory by Oks et al., and the method discussed by Gigosos et al.) that are commonly employed for plasma diagnostics and that describe LIBS plasmas at different levels of approximations. A simple formula for pure hydrogen plasma in thermal equilibrium was also proposed to infer plasma electron density using the H{sub α} line. The results obtained showed that at high hydrogen concentration, the H{sub α} line is affected by considerable self-absorption. In this case, it is preferable to use the H{sub β} line for a reliable calculation of the electron density. - Highlights: • We evaluated the electron density in LIPs utilizing the hydrogen Balmer series. • Plasmas were generated by a Nd:Yag laser (1064 nm) on pure hydrogen gas. • We show that at high hydrogen concentration, H{sub b}eta line is preferable than H{sub a}lpha. • We propose a formula to derive the plasma electron density using the H{sub a}lpha line.

  7. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    CERN Document Server

    Weis, K; Bomans, D J; Davidson, K; Gull, T R; Humphreys, R M; Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this position than when seen directly on eta Car using HST/STIS. Assuming that the reflected spectrum is indeed latitude dependent this indicates that the spectral changes during the event seen pole-on (FOS4) are different from those closer to the equator (directly on the star). In contrast to the spectrum of the star, the scattered spectrum of FOS4 always shows pronounced P Cygni absorption with little variation across the ``spectroscopic event''. After that event an additional high-velocity absorption component appears. The emissio...

  8. Discovery of an activity cycle in the solar analog HD 45184. Exploring Balmer and metallic lines as activity proxy candidates

    Science.gov (United States)

    Flores, M.; González, J. F.; Jaque Arancibia, M.; Buccino, A.; Saffe, C.

    2016-05-01

    Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca ii H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims: We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long- and short-term activity variations. Methods: We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca ii H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca ii H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe ii and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results: We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe ii lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba ii and Ti ii lines present variations at 3σ level, which

  9. Hubble Space Telescope Spectroscopy of the Balmer lines in Sirius B

    CERN Document Server

    Barstow, M A; Holberg, J B; Burleigh, M R; Hubeny, I; Köster, D; Bond, Howard E.

    2005-01-01

    Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from space we can take advantage of the superb spatial resolution of the Hubble Space Telescope to resolve the A and B components. Since the closest approach in 1993, the separation between the two stars has become increasingly favourable and we have recently been able to obtain a spectrum of the complete Balmer line series for Sirius B using HST?s Space Telescope Imaging Spectrograph (STIS). The quality of the STIS spectra greatly exceed that of previous ground-based spectra, and can be used to provide an important determination of the stellar temperature (Teff = 25193K) and gravity (log g = 8.556). In addition we have obtained a new, more accurate, gravitational red-shift of 80.42 +/- 4.83 km s-1 for Sirius B. Combining these results with the photometric data and the Hipparcos parallax we obtain new determinations o...

  10. Measuring the electron density in plasmas from the difference of Lorentzian part of the widths of two Balmer series hydrogen lines

    Energy Technology Data Exchange (ETDEWEB)

    Yubero, C. [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain); García, M.C., E-mail: fa1gamam@uco.es [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain); Dimitrijevic, M.S. [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia); Sola, A.; Gamero, A. [Grupo de Física de Plasmas: Diagnosis, Modelos y Aplicaciones (FQM-136), Edificio A. Einstein (C-2), Campus de Rabanales, Universidad de Córdoba, 14071 Córdoba (Spain)

    2015-05-01

    We present an alternative optical emission spectroscopy method to measure the plasma electron density from the difference of widths of two Balmer series hydrogen lines (H{sub α} and H{sub β}), especially convenient for non-thermal plasmas since with this method, there is no need to know either the gas temperature or the van der Waals contribution to the Lorentzian part of the line. In this paper it has been assumed that the part of full width at half maximum due to Stark broadening can be determined with the approximation of Lorentzian line shape. The method has been applied to the determination of the electron density in an argon microwave-induced plasma maintained at atmospheric pressure, and comparison with the results obtained using other diagnostic methods has been done. - Highlights: • An alternative method to measure the electron density in plasmas from two Balmer series hydrogen lines (H{sub α} and H{sub β}) is presented. • The method is very convenient for plasmas with electron densities of the order of 10{sup 14} cm{sup −3} and above, at low gas temperatures. • It has been applied to the determination of the electron density of an argon microwave plasma at atmospheric pressure. • Results from it are in good agreement with previous ones obtained using other diagnostic methods.

  11. Hydrogen Balmer beta: The separation between line peaks for plasma electron density diagnostics and self-absorption test

    International Nuclear Information System (INIS)

    We propose a diagnostic technique for the measurement of plasma electron number density, Ne, based on the wavelength separation between peaks, ΔλPS, of hydrogen Balmer beta line, Hβ. In favor of the proposed diagnostic technique we demonstrate high sensitivity of ΔλPS on Ne and low sensitivity on plasma elementary processes and plasma parameters that may distort the line profile. These properties of ΔλPS enable reliable Ne plasma diagnostics in the presence of considerable self-absorption. On the basis of available theoretical data tables for the Hβ line profiles, simple Ne=f(ΔλPS) formulas are proposed. Their validity is experimentally confirmed in a low initial pressure pulsed discharge for the Ne range of (0.2–7)⁎1023 m−3. The agreement of the proposed formulas with another diagnostic technique is well within 10%. In addition, the difference in Ne values obtained from peak separation and from the Hβ line width is successfully used as a self-absorption test for line profile. - Highlights: • Separation between peaks of Hβ line proposed for electron density diagnostics. • Derived formulas for peak separations versus electron density. • Formulas tested in high electron density low pressure pulsed arc. • Applications of formulas in optically thick plasmas proven. • Method for hydrogen Balmer beta line self-absorption testing proposed

  12. Broad Balmer Absorption Line Variability: Evidence of Gas Transverse Motion in the QSO SDSS J125942.80+121312.6

    Science.gov (United States)

    Shi, Xiheng; Zhou, Hongyan; Shu, Xinwen; Zhang, Shaohua; Ji, Tuo; Pan, Xiang; Sun, Luming; Zhao, Wen; Hao, Lei

    2016-03-01

    We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of Hβ shows a variation of more than 5σ at a high velocity portion (\\gt 3000 {km} {{{s}}}-1) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He i and optical Fe ii absorptions (λ4233 from b4P5/2 level and λ5169 from a6S5/2) at the same velocity. These Fe ii lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of n({{H}})≈ {10}9.1 {{cm}}-3 and a column density of {N}{col}({{H}})≈ {10}23 {{cm}}-2 for the BOSS data, but the model fails to predict the variations of ionic column densities between the SDSS and BOSS observations if changes in ionizing flux are assumed. We thus propose transverse motion of the absorbing gas being the cause of the observed broad Balmer absorption line variability. In fact, we find that the changes in covering factors of the absorber can well-reproduce all of the observed variations. The absorber is estimated ∼0.94 pc away from the central engine, which is where the outflow likely experiences deceleration due to the collision with the surrounding medium. This scheme is consistent with the argument that LoBAL QSOs may represent the transition from obscured star-forming galaxies to classic QSOs.

  13. Broad Balmer Absorption Line Variability: Evidence of Gas Transverse Motion in the QSO SDSS J125942.80+121312.6

    CERN Document Server

    Shi, Xiheng; Shu, Xinwen; Zhang, Shaohua; Ji, Tuo; Pan, Xiang; Sun, Luming; Zhao, Wen; Hao, Lei

    2016-01-01

    We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of H$\\beta$ shows a variation of more than 5$\\sigma$ at a high velocity portion ($>3000\\ \\mathrm{km\\ s}^{-1}$) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He I and optical Fe II absorptions ($\\lambda 4233$ from b$^4$P$_{5/2}$ level and $\\lambda 5169$ from a$^6$S$_{5/2}$) at the same velocity. These Fe II lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of $n(\\mathrm{H})\\approx 10^{9.1}\\ \\mathrm{cm}^{-3}$ and a column density of $N_{\\mathrm{col}}(\\mathrm{H})\\approx 10^{23}\\ \\mathrm{cm}^{-2}$ for ...

  14. Star formation in NGC 4449: MAMA-detector UV imagery and Fabry-Perot Balmer-line imagery

    Science.gov (United States)

    Hill, Robert S.; Home, Allen T.; Smith, Andrew M.; Bruhweiler, Fred C.; Cheng, K.P.; Hintzen, Paul M. N.; Oliversen, Ronald J.

    1994-01-01

    Using far-ultraviolet (FUV) and Balmer-line imagery, we investigate the star formation history of 22 large OB complexes in the Magellanic irregular galaxy NGC 4449. The FUV luminosity of NGC 4449 is comparable to those of late-type spirals and is greater than that of the LMC by approximately 2.4 mag, indicating substantial star formation in the last 10(exp 8) yr. FUV data were taken using a sounding-rocket telescope with a Multianode Microchannel Array (MAMA) detector, and Balmer-line data were taken using the Goddard Fabry-Perot Imager. The resulting imagery shows bright, roughly coincident FUV and H alpha sources throughout the extent of the visible galaxy. We model these sources using cluster-evolution codes. Although all sources are a few Myr old, clear age differences are found. In particular, several of the most recently active star formation regions are located together in the galaxy's northern periphery, which is apparently coincident with a large H I reservoir. The brightest and most massive OB complexes are found along the northeast-southwest surface brightness ridgeline (the 'bar'). Over the entire galaxy, star formation rates are consistent on timescales of 10(exp 6), 10(exp 8), and 10(exp 9) yr. A history of recent star formation is suggested with two main episodes, one predominantly in the bar ending approximately 5 Myr ago, and an ongoing one associated with an observed H I cloud.

  15. Discovery of an activity cycle in the solar-analog HD 45184. Exploring Balmer and metallic lines as activity proxy candidates

    CERN Document Server

    Flores, M; Arancibia, M Jaque; Buccino, A; Saffe, C

    2016-01-01

    (Abridged) Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca II H&K lines as stellar activity proxies. However, it is unclear if such activity cycles could be identified using other optical lines. Aims. To detect activity cycles in solar-analog stars and determine if these can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184. Methods. We analyse the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. In order to search for line-core fluxes variations, we focus on Ca II H&K and Balmer H$\\alpha$, H$\\beta$ lines, which are usually used as optical chromospheric activity indicators. We calculate the HARPS-S index from Ca II H&K lines and convert it to the Mount-Wilson scale. In addition, we also consider as activity indicators the equivalent widths of Balmer lines. Moreover, we analyse the possible variability of Fe II and other metallic l...

  16. Emission Line Galaxies and Active Galactic Nuclei in WINGS clusters

    CERN Document Server

    Marziani, P; Bettoni, D; Poggianti, B M; Moretti, A; Fasano, G; Fritz, J; Cava, A; Varela, J; Omizzolo, A

    2016-01-01

    We present the analysis of the emission line galaxies members of 46 low redshift (0.04 < z < 0.07) clusters observed by WINGS (WIde-field Nearby Galaxy cluster Survey, Fasano et al. 2006). Emission line galaxies were identified following criteria that are meant to minimize biases against non-star forming galaxies and classified employing diagnostic diagrams. We have examined the emission line properties and frequencies of star forming galaxies, transition objects and active galactic nuclei (AGNs: LINERs and Seyferts), unclassified galaxies with emission lines, and quiescent galaxies with no detectable line emission. A deficit of emission line galaxies in the cluster environment is indicated by both a lower frequency with respect to control samples, and by a systematically lower Balmer emission line equivalent width and luminosity (up to one order of magnitude in equivalent width with respect to control samples for transition objects) that implies a lower amount of ionised gas per unit mass and a lower s...

  17. Continuum and line emission of flares on red dwarf stars

    CERN Document Server

    Morchenko, Egor; Livshits, Moisey

    2015-01-01

    The emission spectrum has been calculated of a homogeneous pure hydrogen layer, which parameters are typical for a flare on a red dwarf. The ionization and excitation states were determined by the solution of steady-state equations taking into account the continuum and all discrete hydrogen levels. We consider the following elementary processes: electron-impact transitions, spontaneous and induced radiative transitions, and ionization by the bremsstrahlung and recombination radiation of the layer itself. The Biberman--Holstein approximation was used to calculate the scattering of line radiation. Asymptotic formulae for the escape probability are obtained for a symmetric line profile taking into account the Stark and Doppler effects. The approximation for the core of the H$-\\alpha$ line by a gaussian curve has been substantiated. The spectral intensity of the continuous spectrum, the intensity of the lines of the Balmer series and the magnitude of the Balmer jump have been calculated. The conditions have been ...

  18. Accretion Disk Line Emission in AGN a Devil's Advocacy

    CERN Document Server

    Sulentic, J W; Dultzin-Hacyan, D

    1998-01-01

    We review the evidence for AGN optical and X-ray broad line emission from an accretion disk. We argue that there is little, if any, statistical evidence to support this assertion. The inconsistency is strongest for the rare class of Balmer profiles that show double peaks. The line profiles predicted by a simple illuminated disk model are often incompatible with the observations. We suggest that the Fe Kalpha line in Seyfert 1 galaxies, where a broad line is most often and most strongly detected, is actually a composite of two lines both with Gaussian profiles; one narrow/unshifted and the other broad/redshifted.

  19. The emission-line pulse pattern in the intermediate polar RX J0558

    OpenAIRE

    Harlaftis, E. T.; Horne, K.

    1999-01-01

    We observed the intermediate polar RX J0558+53 with the 4.2m WHT and find in the pulsed emission lines, a ``corkscrew'' pattern, which indicates a two-pole white dwarf accretion. The ``corkscrew'' pattern consists of two emission-line pulses, separated by half the white dwarf spin period, and moving from red to blue velocities. The detected emission-line pulsations have an amplitude of 1.1--2.7 per cent in the He II and Balmer emission lines on the 545-s spin period of the white dwarf which c...

  20. Comment on “Hydrogen Balmer beta: The separation between line peaks for plasma electron density diagnostics and self-absorption test”

    International Nuclear Information System (INIS)

    In this letter, we present a brief comment regarding the recently published paper by Ivković et al., J Quant Spectrosc Radiat Transf 2015;154:1–8. Reference is made to previous experimental results to indicate that self absorption must have occurred; however, when carefully considering error propagation, both widths and peak-separation predict electron densities within the error margins. Yet the diagnosis method and the presented details on the use of the hydrogen beta peak separation are viewed as a welcomed contribution in studies of laser-induced plasma. - Highlights: • Balmer series Hβ line for determination of electron density. • Compare FWHM with peak-separation method. • Apply to laser induced plasma characterization. • Comment on self-absorption

  1. HYDROGEN BALMER CONTINUUM IN SOLAR FLARES DETECTED BY THE INTERFACE REGION IMAGING SPECTROGRAPH (IRIS)

    Energy Technology Data Exchange (ETDEWEB)

    Heinzel, P. [Astronomical Institute, Academy of Sciences of the Czech Republic, Fričova 298, 25165 Ondřejov (Czech Republic); Kleint, L., E-mail: pheinzel@asu.cas.cz [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland)

    2014-10-20

    We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 Å reached 100%-200% and can be even larger closer to Mg II lines. This is fully consistent with the hydrogen recombination Balmer-continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photospheric continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on the Solar Optical Telescope on board Hinode. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 Å), eliminating seeing effects known to complicate the WLF detection. Moreover, we use a spectral window so far unexplored for flare studies, which provides the potential to study the Balmer continuum, as well as many metallic lines appearing in emission during flares. Combined with future ground-based observations of the continuum near the Balmer limit, we will be able to disentangle various scenarios of the WLF origin. IRIS observations also provide a critical quantitative measure of the energy radiated in the Balmer continuum, which constrains various models of the energy transport and deposit during flares.

  2. HYDROGEN BALMER CONTINUUM IN SOLAR FLARES DETECTED BY THE INTERFACE REGION IMAGING SPECTROGRAPH (IRIS)

    International Nuclear Information System (INIS)

    We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 Å reached 100%-200% and can be even larger closer to Mg II lines. This is fully consistent with the hydrogen recombination Balmer-continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photospheric continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on the Solar Optical Telescope on board Hinode. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 Å), eliminating seeing effects known to complicate the WLF detection. Moreover, we use a spectral window so far unexplored for flare studies, which provides the potential to study the Balmer continuum, as well as many metallic lines appearing in emission during flares. Combined with future ground-based observations of the continuum near the Balmer limit, we will be able to disentangle various scenarios of the WLF origin. IRIS observations also provide a critical quantitative measure of the energy radiated in the Balmer continuum, which constrains various models of the energy transport and deposit during flares

  3. Shock-induced polarized hydrogen emission lines in omicron Ceti

    Science.gov (United States)

    Fabas, N.; Lèbre, A.; Gillet, D.

    2012-05-01

    Hydrogen emission lines in Mira variable stars are a well-known phenomenon whose origin has been established as related to the propagation of radiative hypersonic shock waves throughout the stellar atmosphere. A polarimetric observation by McLean and Coyne [1] made on omicron Ceti (the prototype of Mira variable stars) has revealed the existence of linear polarization signatures associated with Balmer emission lines. However, the polarizing mechanism has never been properly explained so far. The study presented here is the first of its kind since it displays the results of a spectropolarimetric survey of omicron Ceti in the Balmer lines. The survey was made with the NARVAL spectropolarimeter (Telescope Bernard Lyot, France) in full Stokes mode. We did not just confirm the appearance of this polarization but we also and above all showed the temporal variation of the linear polarization in the lines. We conclude that the polarizing mechanism is definitely intrinsic to the shock wave propagation throughout the stellar atmosphere of Mira and give some leads about the nature of this mechanism.

  4. Discovery of polarized line emission in SN1006

    CERN Document Server

    Sparks, W B; Carswell, R F; Long, K S; Cracraft, M

    2015-01-01

    Laming (1990) predicted that the narrow Balmer line core of the ~3000 km/s shock in the SN 1006 remnant would be significantly polarized due to electron and proton impact polarization. Here, based on deep spectrally resolved polarimetry obtained with the European Southern Observatory (ESO)'s Very Large Telescope (VLT), we report the discovery of polarized line emission of polarization degree approx 1.3 percent with position angle orthogonal to the SNR filament. Correcting for an unpolarized broad line component, the implied narrow line polarization is approx 2.0 percent, close to the predictions of Laming (1990). The predicted polarization is primarily sensitive to shock velocity and post-shock temperature equilibration. By measuring polarization for the SN1006 remnant, we validate and enable a new diagnostic that has important applications in a wide variety of astrophysical situations, such as shocks, intense radiation fields, high energy particle streams and conductive interfaces.

  5. DISCOVERY OF POLARIZED LINE EMISSION IN SN 1006

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, W. B.; Pringle, J. E.; Long, K. S.; Cracraft, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Carswell, R. F., E-mail: sparks@stsci.edu [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

    2015-12-10

    Laming predicted that the narrow Balmer line core of the ∼3000 km s{sup −1} shock in the SN 1006 remnant would be significantly polarized due to electron and proton impact polarization. Here, based on deep spectrally resolved polarimetry obtained with the European Southern Observatory (ESO)’s Very Large Telescope (VLT), we report the discovery of polarized line emission with a polarization degree of 1.3% and position angle orthogonal to the SNR filament. Correcting for an unpolarized broad line component, the implied narrow line polarization is ≈2.0%, close to the predictions of Laming. The predicted polarization is primarily sensitive to shock velocity and post-shock temperature equilibration. By measuring polarization for the SN 1006 remnant, we validate and enable a new diagnostic that has important applications in a wide variety of astrophysical situations, such as shocks, intense radiation fields, high energy particle streams, and conductive interfaces.

  6. Polarization of Lyman-α and Balmeremission in proton-hydrogen collisions: a study using first-order Born-Faddeev-type equations

    Science.gov (United States)

    Fathi, R.; Bolorizadeh, M. A.; Shojaei Akbarabadi, F.; Brunger, M. J.

    2012-10-01

    A three-body Born-Faddeev model is devised to calculate the total cross sections of Balmer-α and Lyman-α emissions, for the excitation of hydrogen atoms by proton impact in the energy range of 100 keV-7 MeV. In addition, the polarization alignment factor A20 is calculated and compared against available experimental data to further test the theory. Specifically, here we use the Faddeev-Watson-Lovelace formalism to study the excitation of atomic hydrogen from its ground state to the excited states of n = 2 and 3 and magnetic sublevels l = 0, 1 and 2, wherever applicable. The first-order electronic, A(1)e, and the first-order nuclear, A(1)n, amplitudes are considered in order to calculate the excitation transition matrix (TPT), while a near-the-shell condition is assumed throughout. In addition, our results were used to calculate the first-order form factors. The present results are compared, where possible, with those of other theoretical and experimental works that are currently available in the literature.

  7. Precision Measurement of the Energies and Line Shapes of Antiprotonic Lyman and Balmer Transitions From Hydrogen and Helium Isotopes

    CERN Multimedia

    2002-01-01

    % PS207 \\\\ \\\\ For the study of the antiproton-proton and antiproton-nuclear spin-spin and spin-orbital interaction at threshold a high resolution measurement is proposed of the line shapes and energy shifts of antiprotonic K$\\alpha$ and L$\\alpha$ transitions of hydrogen and helium isotopes. The intense LEAR beam, stopped in the cyclotron trap at low gas pressure, provides a unique~X-ray~source with sufficient brightness. Charge coupled devices with their excellent background rejection and energy resolution allow a precise determination of the strong shifts and widths of the 1s hyperfine states of protonium, in addition the detection of the $\\bar{p}$D K$\\alpha$ transition should be possible. A focussing crystal spectrometer with a resolution $\\Delta$E/E of about l0$ ^- ^{4} $, which is superior in the accuracy of the energy determination by two orders of magnitude as compared to the present detection methods, will be used to measure the energies of the L$\\alpha$ transitions. This permits a first direct measure...

  8. The Redshifted Hydrogen Balmer and Metastable He 1 Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec-scale Accretion Inflow?

    Science.gov (United States)

    Shi, Xi-Heng; Jiang, Peng; Wang, Hui-Yuan; Zhang, Shao-Hua; Ji, Tuo; Liu, Wen-Juan; Zhou, Hong-Yan

    2016-10-01

    The accretion of the interstellar medium onto central super-massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. However, few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example in which the rarely detected hydrogen Balmer and metastable He i absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg ii, Fe ii, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He i* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find that the absorbing medium is exposed to the radiation with ionization parameter U ≈ 10-1.8, and the density is n({{H}})≈ {10}9 {{cm}}-3. Thus the absorbing medium is located ˜4 pc away from the central engine. According to the similarity in the distance and physical conditions between the absorbing medium and the torus, we strongly propose the absorption line system as a candidate for the accretion inflow, which originates in the inner surface of the torus.

  9. Modelado del continuo de Balmer en estrellas Be

    Science.gov (United States)

    Cruzado, A.; Bibbó, I.; Ringuelet, A.

    The second Balmer jump is a distinctive spectral feature very often observed in Be stars. This jump, which is usually attributed to a surrounding extended envelope, may be in emission or in absorption. So, an excess or defect of radiation relative to theoretical atmospheric models describing early-type spectra is originated in the Balmer continuum region. The aim of the present work is to account for the different aspects shown by the Balmer continuum in Be stars. In order to do that, models have been built by adopting different density and temperature distributions and by taking into account every physical process that may take place in extended envelopes of Be stars.

  10. The Redshifted Hydrogen Balmer and Metastable He I Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec Scale Accretion Inflow?

    CERN Document Server

    Shi, Xi-Heng; Wang, Hui-Yuan; Zhang, Shao-Hua; Ji, Tuo; Liu, Wen-Juan; Zhou, Hong-Yan

    2016-01-01

    The accretion of interstellar medium onto the central super massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. But few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example, in which the rarely detected hydrogen Balmer and metastable He I absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg II, Fe II, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He I* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find the absorbing medium is exposed to the radiation with ionization param...

  11. On the role of atomic metastability in the production of Balmer line radiation from ‘cold’ atomic hydrogen, deuterium and hydrogenic ion impurities in fusion edge plasmas

    Science.gov (United States)

    Hey, J. D.

    2012-03-01

    Published arguments, which assign an important role to atomic metastability in the production of ‘narrow’ Zeeman component radiation from the boundary region of fusion plasmas, are examined critically in relation to l-redistribution by proton and electron collisions, and mixing of unperturbed atomic states by the ion microfield and microfield gradient. It is concluded that these important processes indeed severely constrain the contribution from ‘metastable’ states to the generation of the hydrogen Balmer spectra, for electron concentrations above 1012 cm-3, as pointed out before by the present author (Hey et al 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3555). The analysis of collision-induced l-redistribution represents an extension of that used previously (Hey et al 1996 Contrib. Plasma Phys. 36 583), applicable up to higher electron densities. For comparison purposes, we also consider the question of metastability of ionized helium in a low-temperature plasma, and that of some common hydrogenic impurities (C5+ and Ne9+) in a hydrogen (deuterium) fusion plasma. While for low nuclear charge Z the metastability of 2s1/2 levels is quenched by the plasma environment, it is much reduced in high-Z ions owing to the rapid increase with Z of the two-photon electric dipole (2E1) and magnetic dipole (M1) spontaneous transition rates to the ground state, whereas the role of the plasma in these cases is less important. The main new principle elaborated in this work is the sensitivity of atomic line strengths, and hence collision strengths, to perturbation by the plasma environment for transitions between fine-structure sublevels of the same principal quantum number. As the plasma microfield strength grows, ‘allowed’ transitions diminish in strength, while ‘forbidden’ transitions grow. However, owing to violation of the parity selection rule, there is an overall loss of collision strength available to transitions, resulting from the appearance of significant

  12. Hydrogen Balmer Continuum in Solar Flares Detected by the Interface Region Imaging Spectrograph (IRIS)

    CERN Document Server

    Heinzel, Petr

    2014-01-01

    We present a novel observation of the white-light flare (WLF) continuum, which was significantly enhanced during the X1 flare on March 29, 2014 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its NUV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 \\AA\\ reached 100 - 200 % and can be even larger closer to the Mg II lines. This is fully consistent with the hydrogen recombination Balmer continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photospheric continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on Hinode/SOT. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 \\AA), eliminating seeing eff...

  13. Balmer and He I absorption in the nuclear spectrum of NGC 4151

    CERN Document Server

    Hutchings, J B; Krämer, S B; Gabel, J R; Kaiser, M E; Weistrop, D; Gull, T R

    2002-01-01

    Spectra taken with the Space Telescope Imaging Spectrograph (STIS) allow accurate location and extraction of the nuclear spectrum of NGC 4151, with minimal contamination by extended line emission and circumnuclear starlight. Spectra since 1997 show that the P Cygni Balmer and He I absorption seen previously in low nuclear states, is present in higher states, with outflow velocity that changes with the nuclear flux. The phenomenon is discussed in terms of some of the absorbers seen in the UV resonance lines, and outflows from the central source and surrounding torus.

  14. Modeling molecular hyperfine line emission

    CERN Document Server

    Keto, Eric

    2010-01-01

    In this paper we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transitions rates between hyperfine levels are unknown. Hyperfine structure is seen in the rotational spectra of many commonly observed molecules such as HCN, HNC, NH3, N2H+, and C17O. The intensities of these spectral lines can be modeled by numerical techniques such as Lambda-iteration that alternately solve the equations of statistical equilibrium and the equation of radiative transfer. However, these calculations require knowledge of both the radiative and collisional rates for all transitions. For most commonly observed radio frequency spectral lines, only the net collisional rates between rotational levels are known. For such cases, two approximate methods have been suggested. The first method, hyperfine statistical equilibrium (HSE), distributes the hyperfine level populations according to their statistical weight, but allows the population of the rotationa...

  15. Shock-Induced Polarized Hydrogen Emission Lines in the Mira Star omicron Ceti

    CERN Document Server

    Fabas, Nicolas; Gillet, Denis

    2011-01-01

    In the spectra of pulsating stars, especially Mira stars, the detection of intense hydrogen emission lines has been explained by a radiative shock wave, periodically propagating throughout the atmosphere. Previous observation of the Mira star omicron Ceti around a bright maximum of light led to the detection of a strong linear polarization associated to Balmer emissions, although the origin of this phenomenon is not fully explained yet. With the help of spectropolarimetry, we propose to investigate the nature of shock waves propagating throughout the stellar atmosphere and present, for omicron Ceti (the prototype of Mira stars), a full observational study of hydrogen emission lines formed in the radiative region of such a shock. Using the instrument NARVAL, we performed a spectropolarimetric monitoring of omicron Ceti during three consecutive pulsation cycles. All Stokes parameters were systematically collected, with a particular emphasis on the maxima of luminosity, i.e. when a radiative shock wave is suppos...

  16. A new beam emission polarimetry diagnostic for measuring the magnetic field line angle at the plasma edge of ASDEX Upgrade

    Science.gov (United States)

    Viezzer, E.; Dux, R.; Dunne, M. G.

    2016-11-01

    A new edge beam emission polarimetry diagnostic dedicated to the measurement of the magnetic field line angle has been installed on the ASDEX Upgrade tokamak. The new diagnostic relies on the motional Stark effect and is based on the simultaneous measurement of the polarization direction of the linearly polarized π (parallel to the electric field) and σ (perpendicular to the electric field) lines of the Balmer line Dα. The technical properties of the system are described. The calibration procedures are discussed and first measurements are presented.

  17. Segunda discontinuidad de Balmer y procesos físicos en envolturas extendidas de estrellas Be

    Science.gov (United States)

    Bibbo, I.; Cruzado, A.; Ringuelet, A.

    We study a group of Be stars in which the second Balmer jump is observed. Our aim is to correlate the second Balmer jump with other spectral features. Spectroscopic observations were performed with the 2.15 m telescope at Complejo Astronómico el Leoncito, CASLEO (San Juan, Argentina). In December 2001 and August 2002 high resolution echelle spectra were obtained with a REOSC echelle spectrograph. We find that, when a second Balmer jump in emission is observed, an emission in λ = 4233,17 Å of FeII multiplet 27 is also, generally seen. Besides, the electron temperature of the region of the envelope where the second jump is formed is estimated assuming that radiative recombinations cause the flux emission in the Balmer continuum. The temperature values obtained in this way are found correlated with the measure of the second Balmer jump.

  18. Relation between Starlight and Nebular Emission Lines of Star-Forming Galaxies

    Institute of Scientific and Technical Information of China (English)

    Hong-Lin Lu; Hong-Yan Zhou; Ting-Gui Wang; Zhen-Quan Zhuang; Xiao-Bo Dong; Jun-Xian Wang; Cheng Li

    2005-01-01

    We present an exercise that intends to establish a relationship between the strength of nebular emission lines and optical stellar features in the spectrum of a galaxy. After accurately subtracting the stellar continuum and the underlying stellar absorption, we made reliable measurements of the emission lines of all the galaxies in the Sloan Digital Sky Survey Data Release 2 (SDSS DR2). More than 4000 star-forming galaxies with high S/N ratio of both the stellar spectrum and the emission lines are selected. These galaxy spectra are fitted with the 10 PCs of Yip et al., after all the emission line regions have been filtered out. We find that the flux of hydrogen Balmer emission lines, Hα and Hβ can be well recovered from the PCs, while the metal lines are not well reproduced. The fluxes of Hα and Hβ measured from the PC-reconstructed spectra and from the observed spectra agree well with an rms scatter of only ~ 0.1 dex. This result suggests that, with moderate spectral resolution and S/N ratio, the optical stellar spectrum of a galaxy can serve as an indicator of star formation rate.

  19. The emission-line pulse pattern in the intermediate polar RX J0558

    CERN Document Server

    Harlaftis, E T

    1999-01-01

    We observed the intermediate polar RX J0558+53 with the 4.2m WHT and find in the pulsed emission lines, a ``corkscrew'' pattern, which indicates a two-pole white dwarf accretion. The ``corkscrew'' pattern consists of two emission-line pulses, separated by half the white dwarf spin period, and moving from red to blue velocities. The detected emission-line pulsations have an amplitude of 1.1--2.7 per cent in the He II and Balmer emission lines on the 545-s spin period of the white dwarf which compare to 3.5-4.8 per cent for the continuum double-peak pulsations. We image the emission-line pulse pattern and is shown to lag the continuum pulse by 0.12 spin cycles. We interpret the pattern by invoking an accretion curtain from the disrupted, inner disc to the two poles of the magnetic white dwarf. The semi-amplitude of the He II pulse of 408+-35 km/s can be used to constrain the size of the magnetosphere, R ~ 4.1 x 10^4 km, and the magnetic moment of the white dwarf (~2.4 10^32 G cm^3). Power spectra show dominant ...

  20. UV Emission line shifts of symbiotic binaries

    OpenAIRE

    Friedjung, M.; Mikolajewska, J.; Zajczyk, A.; Eriksson, M.

    2010-01-01

    Relative and absolute emission line shifts have been previously found for symbiotic binaries, but their cause was not clear. This work aims to better understand the emission line shifts. Positions of strong emission lines were measured on archival UV spectra of Z And, AG Dra, RW Hya, SY Mus and AX Per and relative shifts between the lines of different ions compared. Profiles of lines of RW Hya and Z And were also examined. The reality of the relative shift between resonance and intercombinati...

  1. Spatially-resolved HST Grism Spectroscopy of a Lensed Emission Line Galaxy at z~1

    CERN Document Server

    Frye, Brenda L; Bowen, David V; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

    2012-01-01

    We take advantage of gravitational lensing amplification by Abell 1689 (z=0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i_775=27.3 via slitless grism spectroscopy. One ELG (at z=0.7895) is very bright owing to lensing magnification by a factor of ~4.5. Several Balmer emission lines detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M_* = 2 x 10^9 solar masses) with a high specific star formation rate (~20 /Gyr). From the blue emission lines we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H)=8.8 +/- 0.2). We break the continuous line-emitting region of this giant arc into seven ~1kpc bins (intrinsic size) and measure a variety of metallicity dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region...

  2. "Direct" Gas-phase Metallicities, Stellar Properties, and Local Environments of Emission-line Galaxies at Redshift below 0.90

    CERN Document Server

    Ly, Chun; Nagao, Tohru; Kashikawa, Nobunari; Shimasaku, Kazuhiro; Hayashi, Masao

    2013-01-01

    Using deep narrow-band imaging and optical spectroscopy from Keck and MMT, we identify a sample of 20 emission-line galaxies at z=0.065-0.90 where the weak auroral emission line, [O III]4363, is detected at >3\\sigma. These detections allow us to determine the gas-phase metal abundances using the "direct" method. After correcting for dust attenuation using Balmer decrements, we find that 10 of these low-mass galaxies are extremely metal-poor with 12+log(O/H) 1 galaxies.

  3. The Of emission lines near 4650 A

    Science.gov (United States)

    Underhill, A. B.; Gilroy, K. K.; Hill, G. M.

    1989-09-01

    Rectified, normalized, high S/N intensity tracings of nine Of stars were obtained from Reticon spectra in the 4550-4800-A region. The well-known relatively sharp Of emission lines are seen to stand on pedestals of broad weak emission somewhat like the broad emission lines from WR stars. It is suggested that cascades following dielectronic recombination may be an important process driving some lines of N III, C III, and C IV into the emission of Of stars, and that the sharp Of lines come from plasma that is stationary with respect to the star. The broad emission features show an extensive low-density wind from each star. The results imply that the detection of two, more or less equal, broad jumps in the rest spectra of galaxies at about 4640 and 4686 A is more indicative of Of stars than of WR stars.

  4. The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross

    Science.gov (United States)

    Braibant, L.; Hutsemékers, D.; Sluse, D.; Anguita, T.

    2016-07-01

    We investigate the kinematics and ionization structure of the broad emission line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein cross) using differential microlensing in the high- and low-ionization broad emission lines. We combine visible and near-infrared spectra of the four images of the lensed quasar and detect a large-amplitude microlensing effect distorting the high-ionization CIV and low-ionization Hα line profiles in image A. While microlensing only magnifies the red wing of the Balmer line, it symmetrically magnifies the wings of the CIV emission line. Given that the same microlensing pattern magnifies both the high- and low-ionization broad emission line regions, these dissimilar distortions of the line profiles suggest that the high- and low-ionization regions are governed by different kinematics. Since this quasar is likely viewed at intermediate inclination, we argue that the differential magnification of the blue and red wings of Hα favors a flattened, virialized, low-ionization region whereas the symmetric microlensing effect measured in CIV can be reproduced by an emission line formed in a polar wind, without the need of fine-tuned caustic configurations. Based on observations made with the ESO-VLT, Paranal, Chile; Proposals 076.B-0197 and 076.B-0607 (PI: Courbin).

  5. Balmer and Rydberg Equations for Hydrogen Spectra Revisited

    OpenAIRE

    Heyrovska, Raji

    2011-01-01

    Balmer equation for the atomic spectral lines was generalized by Rydberg. Here it is shown that 1) while Bohr's theory explains the Rydberg constant in terms of the ground state energy of the hydrogen atom, quantizing the angular momentum does not explain the Rydberg equation, 2) on reformulating Rydberg's equation, the principal quantum numbers are found to correspond to integral numbers of de Broglie waves and 3) the ground state energy of hydrogen is electromagnetic like that of photons an...

  6. Supermassive black holes and spectral emission lines

    International Nuclear Information System (INIS)

    It is widely accepted that active galactic nuclei (AGN) are hosting a supermassive black hole in their center. The supermassive black hole is actively fueled by surrounding gas through an accretion disk, which produces a broad band continuum (from X-ray to radio emission). The hard photons from the accretion disk create the photoionized plasma around the central black hole, which emits a number of broad emission lines. Therefore, one of the signatures of the strong activity in galaxies is the emission of the broad spectral lines (line widths of several 1000 km/s), which are seen only in a fraction of AGN, so called Type 1 AGN. These broad emission lines often show very complex line profiles, usually strongly variable in time. Here we will describe the basic properties of the broad emission lines and how can we use them to derive the properties of the central supermassive black hole, i.e., the mass and spin, or see signatures of supermassive binary black holes

  7. Local Group Galaxy Emission-line Survey

    Science.gov (United States)

    Blaha, Cindy; Baildon, Taylor; Mehta, Shail; Garcia, Edgar; Massey, Philip; Hodge, Paul W.

    2015-01-01

    We present the results of the Local Group Galaxy Emission-line Survey of Hα emission regions in M31, M33 and seven dwarf galaxies in (NGC6822, IC10, WLM, Sextans A and B, Phoenix and Pegasus). Using data from the Local Group Galaxy Survey (LGGS - see Massey et al, 2006), we used continuum-subtracted Ha emission line images to define emission regions with a faint flux limit of 10 -17 ergs-sec-1-cm-2above the background. We have obtained photometric measurements for roughly 7450 Hα emission regions in M31, M33 and five of the seven dwarf galaxies (no regions for Phoenix or Pegasus). Using these regions, with boundaries defined by Hα-emission flux limits, we also measured fluxes for the continuum-subtracted [OIII] and [SII] images and constructed a catalog of Hα fluxes, region sizes and [OIII]/ Hα and [SII]/ Hα line ratios. The HII region luminosity functions and size distributions for the spiral galaxies M31 and M33 are compared with those of the dwarf galaxies NGC 6822 and IC10. For M31 and M33, the average [SII]/ Hα and [OIII]/ Hα line ratios, plotted as a function of galactocentric radius, display a linear trend with shallow slopes consistent with other studies of metallicity gradients in these galaxies. The galaxy-wide averages of [SII]/ Hα line ratios correlate with the masses of the dwarf galaxies following the previously established dwarf galaxy mass-metallicity relationship. The slope of the luminosity functions for the dwarf galaxies varies with galaxy mass. The Carleton Catalog of this Local Group Emission-line Survey will be made available on-line.

  8. UV Emission line shifts of symbiotic binaries

    CERN Document Server

    Friedjung, M; Zajczyk, A; Eriksson, M

    2010-01-01

    Relative and absolute emission line shifts have been previously found for symbiotic binaries, but their cause was not clear. This work aims to better understand the emission line shifts. Positions of strong emission lines were measured on archival UV spectra of Z And, AG Dra, RW Hya, SY Mus and AX Per and relative shifts between the lines of different ions compared. Profiles of lines of RW Hya and Z And were also examined. The reality of the relative shift between resonance and intercombination lines of several times ionised atoms was clearly shown except for AG Dra. This redshift shows a well defined variation with orbital phase for Z And and RW Hya. In addition the intercombination lines from more ionised atoms and especially OIV are redshifted with respect to those from less ionised atoms. Other effects are seen in the profiles. The resonance-intercombination line shift variation can be explained in quiescence by P Cygni shorter wavelength component absorption, due to the wind of the cool component, which ...

  9. Investigating Starburst Galaxy Emission Line Equivalent Widths

    Science.gov (United States)

    Meskhidze, Helen; Richardson, Chris T.

    2016-01-01

    Modeling star forming galaxies with spectral synthesis codes allows us to study the gas conditions and excitation mechanisms that are necessary to reproduce high ionization emission lines in both local and high-z galaxies. Our study uses the locally optimally-emitting clouds model to develop an atlas of starburst galaxy emission line equivalent widths. Specifically, we address the following question: What physical conditions are necessary to produce strong high ionization emission lines assuming photoionization via starlight? Here we present the results of our photoionization simulations: an atlas spanning 15 orders of magnitude in ionizing flux and 10 orders of magnitude in hydrogen density that tracks over 150 emission lines ranging from the UV to the near IR. Each simulation grid contains ~1.5x104 photoionization models calculated by supplying a spectral energy distribution, grain content, and chemical abundances. Specifically, we will be discussing the effects on the emission line equivalent widths of varying the metallicity of the cloud, Z = 0.2 Z⊙ to Z = 5.0 Z⊙, and varying the star-formation history, using the instantaneous and continuous evolution tracks and the newly released Starburst99 Geneva rotation tracks.

  10. The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross

    CERN Document Server

    Braibant, Lorraine; Sluse, Dominique; Anguita, Timo

    2016-01-01

    We investigate the kinematics and ionization structure of the broad emission line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein cross) using differential microlensing in the high- and low-ionization broad emission lines. We combine visible and near-infrared spectra of the four images of the lensed quasar and detect a large-amplitude microlensing effect distorting the high-ionization CIV and low-ionization H$\\alpha$ line profiles in image A. While microlensing only magnifies the red wing of the Balmer line, it symmetrically magnifies the wings of the CIV emission line. Given that the same microlensing pattern magnifies both the high- and low-ionization broad emission line regions, these dissimilar distortions of the line profiles suggest that the high- and low-ionization regions are governed by different kinematics. Since this quasar is likely viewed at intermediate inclination, we argue that the differential magnification of the blue and red wings of H$\\alpha$ favors a flattened, viri...

  11. On the accuracy of Black Hole Mass estimation from Broad Emission Lines

    Science.gov (United States)

    Mejia-Restrepo, Julian; Trakhtenbrot, Benny; Lira, Paulina; Netzer, Hagai; Capellupo, Daniel

    2016-08-01

    In this talk we compare single-epoch (SE) black hole mass (MBH) estimates based on low ionization (Hα, Hβ, and MgII) and high ionization (CIV) broad emission lines. We also examine the implications of different continuum modeling approaches in line width and MBH measurements. For this purpose we use a sample of 39 unobscured AGNs at z=1.55 selected to cover a large range in MBH (2.0dex) and L/Ledd (2.5dex) and observed by X-shooter. We find that using a local power-law continuum instead of a physically-motivated thin disk continuum leads to only slight underestimation of the FWHM of the lines and the associated MBH(FWHM). However, the line dispersion σ and associated MBH(σ) are strongly affected by the continuum placement providing less reliable mass estimates. We find that low ionization lines provides reliable virial MBH estimation. However, the CIV line is not reliable in the majority of the cases, indicating that the gas emitting this line may not be virialized. We find that Hα, Hβ show similar line widths and that FWHM(MgII) is about 30% narrower than FWHM(Hβ) . We test and confirm several recent suggestions to improve the accuracy in CIV-based mass estimates, relying on other UV emission lines. However, we find that such improvements do not help in reducing the scatter between CIV-based and Balmer-line-based mass estimates. This work has been recently accepted for publication in MNRAS.

  12. Emission lines from hot astrophysical plasmas

    Science.gov (United States)

    Raymond, John C.

    The spectral lines which dominate the X-ray emission of hot, optically thin astrophysical plasmas reflect the elemental abundances, temperature distribution, and other physical parameters of the emitting gas. The accuracy and level of detail with which these parameters can be inferred are limited by the measurement uncertainties and uncertainties in atomic rates used to compute the model spectrum. This paper discusses the relative importance and the likely uncertainties in the various atomic rates and the likely uncertainties in the overall ionization balance and spectral line emissivities predicted by the computer codes currently used to fit X-ray spectral data.

  13. Molecular Emission Line Formation in Prestellar Cores

    CERN Document Server

    Pavlyuchenkov, Ya; Shustov, B; Henning, T; Launhardt, R; Semenov, D

    2008-01-01

    We investigate general aspects of molecular line formation under conditions which are typical of prestellar cores. Focusing on simple linear molecules, we study formation of their rotational lines by radiative transfer simulations. We present a thermalization diagram to show the effects of collisions and radiation on the level excitation. We construct a detailed scheme (contribution chart) to illustrate the formation of emission line profiles. This chart can be used as an efficient tool to identify which parts of the cloud contribute to a specific line profile. We show how molecular line characteristics for uniform model clouds depend on hydrogen density, molecular column density, and kinetic temperature. The results are presented in a 2D plane to illustrate cooperative effects of the physical factors. We also use a core model with a non-uniform density distribution and chemical stratification to study the effects of cloud contraction and rotation on spectral line maps. We discuss the main issues that should ...

  14. The line emissions and polarization in blazars

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.

  15. An Atlas of Starburst Galaxy Emission Lines

    Science.gov (United States)

    Meskhidze, Helen; Richardson, Chris T.; Ferland, Gary J.

    2015-01-01

    Recent observations of high ionization lines (e.g. [Ne V] and He II λ4686) from star-forming regions have prompted a need to study the production mechanisms of these high ionization lines. Our study addresses the following questions: 1. What are specific cloud parameters that influence the strength of emission lines in starburst galaxies? 2. How can these parameters be tuned in simulations to match observations? We adopt the locally optimally emitting cloud model, a model previously used to study AGN, for our study of star-forming regions. We present the results of hundreds of photoionization simulations spanning 15 orders of magnitude in hydrogen ionizing photon flux and 10 orders of magnitude in hydrogen density. We vary both properties of the starbursts (SEDs, evolutionary histories, ages), as well as cloud properties (such as the abundances and metallicity), tracking nearly 100 emission lines ranging from the UV to the near IR. Finally, we compare these results to the results of other studies on star-forming regions. The results of our photoionization calculations should prove useful for the analysis of starburst galaxy emission-line data.

  16. Balmer and Rydberg Equations for Hydrogen Spectra Revisited

    CERN Document Server

    Heyrovska, Raji

    2011-01-01

    Balmer equation for the atomic spectral lines was generalized by Rydberg. Here it is shown that 1) while Bohr's theory explains the Rydberg constant in terms of the ground state energy of the hydrogen atom, quantizing the angular momentum does not explain the Rydberg equation, 2) on reformulating Rydberg's equation, the principal quantum numbers are found to correspond to integral numbers of de Broglie waves and 3) the ground state energy of hydrogen is electromagnetic like that of photons and the frequency of the emitted or absorbed light is the difference in the frequencies of the electromagnetic energy levels.

  17. Newly Identified Rydberg Emission Lines in Novae

    Science.gov (United States)

    Lynch, David K.; Rudy, R. J.; Bernstein, L. S.

    2008-09-01

    Newly Identified Rydberg Emission Lines in Novae David K. Lynch, Richard. J. Rudy (The Aerospace Corporation) & Lawrence S. Bernstein (Spectral Sciences, Inc.) Novae spectra in the near infrared frequently show a set of six emission lines that have not been positively identified (Williams, Longmore, & Geballe 1996, MNRAS, 279, 804; Lynch et al. 2001, AJ, 122, 2013; Rudy et al. 2002 ApJ, 573, 794; Lynch et al. 2004 Astron. J. 127, 1089-1097). These lines are at 0.8926, 1.1114, 1.1901, 1.5545, 2.0996 and 2.425 µm ± 0.005 µm. Krautter et al. (1984 A&A 137, 304) suggested that three of the lines were due to rydberg (hydrogenic) transitions in an unspecified atomic species that was in the 4th or 5th ionization stage (core charge = 4 & 5). We believe that Krautter et al.'s explanation is correct based on 4 additional lines that we have identified in the visible and near infrared spectrum of V723 Cassiopeiae. The observed Rydberg lines appear to originate from high angular momentum states with negligible quantum defects. The species cannot be determined with any certainty because in rydberg states, the outer electron sees a nucleus shielded by the inner electrons and together the inner atom appears to have a charge of +1, like hydrogen. As a result, the atom looks hydrogenic and species such as CV, NV, OV, MgV, SiV, etc. have their rydberg transitions at very similar wavelengths. All the lines represent permitted transitions, most likely formed by recombination. Atoms with core charges 4, 5 & 6 are rarely seen in the astrophysical environment because an extremely hot radiation field is necessary to ionize them. Thermonuclear runaways on the surface of a white dwarf can reach millions of degrees K, and thus there are enough X-ray photons available to achieve the necessary high ionization levels.

  18. Linear Polarization Measurements of Chromospheric Emission Lines

    Science.gov (United States)

    Sheeley, N. R., Jr.; Keller, C. U.

    2003-01-01

    We have used the Zurich Imaging Stokes Polarimeter (ZIMPOL I) with the McMath-Pierce 1.5 m main telescope on Kitt Peak to obtain linear polarization measurements of the off-limb chromosphere with a sensitivity better than 1 x 10(exp -5). We found that the off-disk observations require a combination of good seeing (to show the emission lines) and a clean heliostat (to avoid contamination by scattered light from the Sun's disk). When these conditions were met, we obtained the following principal results: 1. Sometimes self-reversed emission lines of neutral and singly ionized metals showed linear polarization caused by the transverse Zeeman effect or by instrumental cross talk from the longitudinal Zeeman effect in chromospheric magnetic fields. Otherwise, these lines tended to depolarize the scattered continuum radiation by amounts that ranged up to 0.2%. 2. Lines previously known to show scattering polarization just inside the limb (such as the Na I lambda5889 D2 and the He I lambda5876 D3 lines) showed even more polarization above the Sun's limb, with values approaching 0.7%. 3. The O I triplet at lambda7772, lambda7774, and lambda7775 showed a range of polarizations. The lambda7775 line, whose maximum intrinsic polarizability, P(sub max), is less than 1%, revealed mainly Zeeman contributions from chromospheric magnetic fields. However, the more sensitive lambda7772 (P(sub max) = 19%) and lambda7774 (P(sub max) = 29%) lines had relatively strong scattering polarizations of approximately 0.3% in addition to their Zeeman polarizations. At times of good seeing, the polarization spectra resolve into fine structures that seem to be chromospheric spicules.

  19. Active galactic nuclei at z ˜ 1.5 - II. Black hole mass estimation by means of broad emission lines

    Science.gov (United States)

    Mejía-Restrepo, J. E.; Trakhtenbrot, B.; Lira, P.; Netzer, H.; Capellupo, D. M.

    2016-07-01

    This is the second in a series of papers aiming to test how the mass (MBH), accretion rate (Ṁ) and spin (a*) of supermassive black holes (SMBHs) determine the observed properties of type I active galactic nuclei (AGN). Our project utilizes a sample of 39 unobscured AGN at z ≃ 1.55 observed by Very Large Telescope/X-Shooter, selected to map a large range in MBH and L/LEdd and covers the most prominent UV-optical (broad) emission lines, including Hα, Hβ, Mg II λ2798 and C IV λ1549. This paper focuses on single-epoch, `virial' MBH determinations from broad emission lines and examines the implications of different continuum modelling approaches in line width measurements. We find that using a local power-law continuum instead of a physically motivated thin disc continuum leads to only slight underestimation of the full width at half-maximum (FWHM) of the lines and the associated MBH(FWHM). However, the line dispersion σline and associated MBH(σline) are strongly affected by the continuum placement and provides less reliable mass estimates than FWHM-based methods. Our analysis shows that Hα, Hβ and Mg II can be safely used for virial MBH estimation. The C IV line, on the other hand, is not reliable in the majority of the cases; this may indicate that the gas emitting this line is not virialized. While Hα and Hβ show very similar line widths, the mean FWHM(Mg II) is about 30 per cent narrower than FWHM(Hβ). We confirm several recent suggestions to improve the accuracy in C IV-based mass estimates, relying on other UV emission lines. Such improvements do not reduce the scatter between C IV-based and Balmer-line-based mass estimates.

  20. Revisiting correlations between broad-line and jet emission variations for AGNs: 3C 120 and 3C 273

    Science.gov (United States)

    Liu, H. T.; Bai, J. M.; Feng, H. C.; Li, S. K.

    2015-06-01

    We restudy the issue of cross-correlations between broad-line and jet emission variations, and aim to locate the position of a radio (and gamma-ray) emitting region in a jet of active galactic nuclei. Considering the radial profiles of the radius and number density of clouds in a spherical broad-line region (BLR), we derive new formulae connecting the jet-emitting position Rjet to the time lag τob between broad-line and jet emission variations, and the BLR radius. Also, formulae are derived for a disc-like BLR and a spherical shell BLR. The model-independent flux randomization/random subset selection method is used to estimate τob. For 3C 120, positive lags of about 0.3 yr are found between the 15 GHz emission and the Hβ, Hγ and He II λ4686 lines, including broad-line data in a newly published paper, indicating that the line variations lead the 15 GHz ones. Each of the broad-line light curves corresponds to a radio outburst. Rjet = 1.1-1.5 parsec (pc) is obtained for 3C 120. For 3C 273, a common feature of negative time lags is found in the cross-correlation functions between light curves of radio emission and the Balmer lines, as well as Lyα λ1216 and C IV λ1549 lines. Rjet = 1.0-2.6 pc is obtained for 3C 273. The estimated Rjet is comparable for 3C 120 and 3C 273, and the gamma-ray-emitting positions will be within ˜1-3 pc from the central engines. Comparisons show that the cloud number density and radius radial distributions and the BLR structures have only negligible effects on Rjet.

  1. Evolution of [O III] λ5007 Emission-line Profiles in Narrow Emission-line Galaxies

    Science.gov (United States)

    Wang, J.; Mao, Y. F.; Wei, J. Y.

    2011-11-01

    The active galactic nucleus (AGN)-host co-evolution issue is investigated here by focusing on the evolution of the [O III] λ5007 emission-line profile. A large sample of narrow emission-line galaxies is selected from the Max-Planck Institute for Astrophysics/Johns Hopkins University Sloan Digital Sky Survey DR7 catalog to simultaneously measure both the [O III] line profile and circumnuclear stellar population in an individual spectrum. By requiring that (1) the [O III] line signal-to-noise ratio is larger than 30 and (2) the [O III] line width is larger than the instrumental resolution by a factor of two, our sample is narrowed down to 2333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 star-forming galaxies. In addition to the commonly used profile parameters (i.e., line centroid, relative velocity shift, and velocity dispersion), two dimensionless shape parameters, skewness and kurtosis, are used to quantify the line shape deviation from a pure Gaussian function. We show that the transition galaxies are systematically associated with narrower line widths and weaker [O III] broad wings than the AGNs, which implies that the kinematics of emission-line gas are different in the two kinds of objects. By combining the measured host properties and line shape parameters, we find that the AGNs with stronger blue asymmetries tend to be associated with younger stellar populations. However, a similar trend is not identified in the transition galaxies. The failure likely results from a selection effect in which the transition galaxies are systematically associated with younger stellar populations than the AGNs. The evolutionary significance revealed here suggests that both narrow-line region kinematics and outflow feedback in AGNs co-evolve with their host galaxies.

  2. EVOLUTION OF [O III] λ5007 EMISSION-LINE PROFILES IN NARROW EMISSION-LINE GALAXIES

    International Nuclear Information System (INIS)

    The active galactic nucleus (AGN)-host co-evolution issue is investigated here by focusing on the evolution of the [O III] λ5007 emission-line profile. A large sample of narrow emission-line galaxies is selected from the Max-Planck Institute for Astrophysics/Johns Hopkins University Sloan Digital Sky Survey DR7 catalog to simultaneously measure both the [O III] line profile and circumnuclear stellar population in an individual spectrum. By requiring that (1) the [O III] line signal-to-noise ratio is larger than 30 and (2) the [O III] line width is larger than the instrumental resolution by a factor of two, our sample is narrowed down to 2333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 star-forming galaxies. In addition to the commonly used profile parameters (i.e., line centroid, relative velocity shift, and velocity dispersion), two dimensionless shape parameters, skewness and kurtosis, are used to quantify the line shape deviation from a pure Gaussian function. We show that the transition galaxies are systematically associated with narrower line widths and weaker [O III] broad wings than the AGNs, which implies that the kinematics of emission-line gas are different in the two kinds of objects. By combining the measured host properties and line shape parameters, we find that the AGNs with stronger blue asymmetries tend to be associated with younger stellar populations. However, a similar trend is not identified in the transition galaxies. The failure likely results from a selection effect in which the transition galaxies are systematically associated with younger stellar populations than the AGNs. The evolutionary significance revealed here suggests that both narrow-line region kinematics and outflow feedback in AGNs co-evolve with their host galaxies.

  3. Shocked POststarbust Galaxy Survey I: Candidate Poststarbust Galaxies with Emission Line Ratios Consistent with Shocks

    CERN Document Server

    Alatalo, Katherine; Rich, Jeffrey A; Appleton, Philip N; Kewley, Lisa J; Lacy, Mark; Lanz, Lauranne; Medling, Anne M; Nyland, Kristina

    2016-01-01

    [Abridged] There are many mechanisms by which galaxies can transform from blue, star-forming spirals to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent studies of nearby case studies seem to have identified a population of galaxies that quench "quietly." Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify galaxies in an earlier phase of transformation, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the OSSY measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1,067 SPOG candidates (SPOGs*) within z = 0.2. SPOGs* represent 0.7% of emission line galaxies (and 0.2% of OSSY). SPOGs* colors suggest that they ...

  4. Data-model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

    Science.gov (United States)

    Bishop, J.; Mierkiewicz, E. J.; Roesler, F. L.; Gómez, J. F.; Morales, C.

    2004-05-01

    Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer α Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman β, Lyman γ and He 584 Å emission intensities. In this paper, coincident EURD Lyman β and PBO Balmer α radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A data-model comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman β irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

  5. Interpreting broad emission-line variations I : Factors influencing the emission-line response

    CERN Document Server

    Goad, M R

    2014-01-01

    We investigate the sensitivity of the measured broad emission-line responsivity dlog f_line/dlog f_cont to continuum variations in the context of straw-man BLR geometries of varying size with fixed BLR boundaries, and for which the intrinsic emission-line responsivity is known a priori. We find for a generic emission-line that the measured responsivity, delay and maximum of the cross-correlation function are correlated for characteristic continuum variability timescales T_char less than the maximum delay for that line tau_max(line) for a particular choice of BLR geometry and observer orientation. The above correlations are manifestations of geometric dilution arising from reverberation effects within the spatially extended BLR. When present, geometric dilution reduces the measured responsivity, delay and maximum of the cross-correlation function. We also find that the measured responsivity and delay show a strong dependence on light-curve duration, with shorter campaigns resulting in smaller than expected val...

  6. Line emission from optically thick relativistic accretion tori

    OpenAIRE

    Fuerst, Steven V.; Wu, Kinwah

    2007-01-01

    We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderat...

  7. Star formation activity in Balmer break galaxies at $z$ < 1.5

    CERN Document Server

    Tello, J Díaz; Padilla, N; Akiyama, M; Fujishiro, N; Yoshikawa, T; Hanami, H

    2016-01-01

    Aims. We present a spectroscopic study of the properties of 64 Balmer break galaxies that show signs of star formation. The studied sample of star-forming galaxies spans a redshift range from 0.094 to 1.475 with stellar masses in the range 10$^{8}-$10$^{12}$ $M_{\\odot}$. The sample also includes eight broad emission line galaxies with redshifts between 1.5 $emission line luminosities and investigated the dependence of the SFR and specific SFR (SSFR) on the stellar mass and color. Furthermore, we investigated the evolution of these relations with the redshift. Results. We found that the SFR correlates with the stellar mass, our data is consistent with previous results from other authors in that there is a break in the correlation, which reveals the presence of massive galaxies with lower SFR values (i.e., decreasing star formation). We also note an anticorrelation for the SSFR with the stellar mass. Again in this case, our data is also consis...

  8. FIR line emission from high redshift galaxies

    CERN Document Server

    Vallini, Livia; Ferrara, Andrea; Baek, Sunghye

    2013-01-01

    By combining high resolution, radiative transfer cosmological simulations of z~6 galaxies with a sub-grid multi-phase model of their interstellar medium we derive the expected intensity of several far infrared (FIR) emission lines ([C II] 158 micron, [O I] 63 micron, and [N II] 122 micron) for different values of the gas metallicity, Z. For Z = Z_sun the [C II] spectrum is very complex due to the presence of several emitting clumps of individual size < 3 kpc; the peak is displaced from the galaxy center by ~100 km/s. While the [O I] spectrum is also similarly displaced, the [N II] line comes predominantly from the central ionized regions of the galaxy. When integrated over ~500 km/s, the [C II] line flux is 185 mJy km/s; 95% of such flux originates from the cold (T~250 K) H I phase, and only 5% from the warm (T~5000 K) neutral medium. The [O I] and [N II] fluxes are ~6 and ~90 times lower than the [C II] one, respectively. By comparing our results with observations of Himiko, the most extended and luminous...

  9. X-ray line emission produced in clump bow shocks

    OpenAIRE

    Cassinelli, Joe P.; Ignace, R.; Waldron, W.; Cho, J.; Murphy, N; Lazarian, A.

    2008-01-01

    We summarize Chandra observations of the emission line profiles from 17 OB stars. The lines tend to be broad and unshifted. The forbidden/intercombination line ratios arising from Helium-like ions provide radial distance information for the X-ray emission sources, while the H-like to He-like line ratios provide X-ray temperatures, and thus also source temperature versus radius distributions. OB stars usually show power law differential emission measure distributions versus temperature. In mod...

  10. Continuum and line emission in Cygnus A

    Science.gov (United States)

    Stockton, Alan; Ridgway, Susan E.; Lilly, Simon J.

    1994-08-01

    We present the results from (1) imaging observations of Cygnus A in five essentially line-free continuum bands with central wavelengths ranging from 0.34 to 2.1 microns. (2) imaging observations in five narrowband filters centered on the emission lines H beta(O III) lambda5007, H alpha(N II) lambda6583, and (S II) lambda lambda6716, 6731, and (3) deep spectroscopy covering the entire central region of Cyg A. We confirm that the featureless spectrum component is to be identified with the prominent double morphology at the center of Cyg A, but uncertainties in the distribution of the dust in this region tend to limit the accuracy with which we can determine its morphology and spectral-energy distribution (SED). From regions that appear to be least affected by obscuration, we find fv is approximately v-0.1 for this component. This SED could be consistent with free-free emission, a population of young stars, or a quasar continuum scattered by electrons, but probably not with a quasar continuum scattered by dust, which would be bluer. Our spectroscopy places an upper limit on the equivalent width of broad H beta that is well below that of typical quasars, showing that this flat-spectrum component (FSC) is almost certainly not dominated by scattered quasar radiation. Appeals to scattering by hot electrons to smear the scattered broad lines into invisibility appear to fail because the large density scale height of the electrons and the inefficiency of electron scattering should result in smoother and more extensive structure than we observe. Although the relative SED is consistent with free-free emission, the required amount of hot gas violates other observational constraints. At high angular resolution, the apparent morphology of the FSC is spiral-like. Although this impression may be partly due to obscuration, the distribution of the dust itself only serves to reinforce the spiral-like nature of the material with which it is associated. We conclude that the FSC is most

  11. First Science with SHARDS: emission line galaxies

    CERN Document Server

    Cava, Antonio

    2012-01-01

    SHARDS (Survey for High-z Absorption Red & Dead Sources) is an unbiased ultra-deep spectro-photometric survey with GTC@OSIRIS aimed at selecting and studying massive passively evolving galaxies at z=1.0-2.3 using a set of 24 medium-band filters (FWHM\\sim17 nm) at 500-950 nm in GOODS-N. Our observing strategy is optimized to detect at z>1 the prominent Mg absorption feature at rest-frame ~280 nm, a distinctive, necessary, and sufficient feature of evolved stellar populations. Nonetheless, the data quality allow a plethora of studies on galaxy populations, including Emission Lines Galaxies (ELGs) about which we have started our first science verification project presented in this contribution.

  12. Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

    Science.gov (United States)

    Lomanowski, B. A.; Meigs, A. G.; Sharples, R. M.; Stamp, M.; Guillemaut, C.; Contributors, JET

    2015-11-01

    A parametrised spectral line profile model is formulated to investigate the diagnostic scope for recovering plasma parameters from hydrogenic Balmer and Paschen series spectroscopy in the context of JET-ILW divertor plasmas. The separate treatment of Zeeman and Stark contributions in the line model is tested against the PPP-B code which accounts for their combined influence on the spectral line shape. The proposed simplified model does not fully reproduce the Stark-Zeeman features for the α and β transitions, but good agreement is observed in the line width and wing profiles, especially for n  >  5. The line model has been applied to infer radial density profiles in the JET-ILW divertor with generally good agreement between the D 5\\to 2 , 5\\to 3 , 6\\to 2 , 7\\to 2 and 9\\to 2 lines for high recycling and detached conditions. In an L-mode detached plasma pulse the Langmuir probe measurements typically underestimated the density by a factor 2-3 and overestimated the electron temperature by a factor of 5-10 compared to spectroscopically derived values. The line model is further used to generate synthetic high-resolution spectra for low-n transitions to assess the potential for parameter recovery using a multi-parametric fitting technique. In cases with 4 parameter fits with a single Maxwellian neutral temperature component the D 4\\to 3 line yields the best results with parameter estimates within 10% of the input values. For cases with 9 parameter fits inclusive of a multi-component neutral velocity distribution function the quality of the fits is degraded. Simultaneous fitting of the D 3\\to 2 and 4\\to 3 profiles improves the fit quality significantly, highlighting the importance of complementary spectroscopic measurements for divertor plasma emission studies.

  13. Molecular clouds photoevaporation and FIR line emission

    CERN Document Server

    Vallini, L; Pallottini, A; Gallerani, S

    2016-01-01

    With the aim of improving predictions on the far infrared (FIR) line emission from Giant Molecular Clouds (GMC), we have studied the effects of photoevaporation (PE) produced by external far-ultraviolet (FUV) and ionizing (extreme-ultraviolet, EUV) radiation on the GMC structure. Our model includes: (i) an observationally-based inhomogeneous GMC density field, and (ii) its time evolution during the PE process. We find that the photoevaporation timescale, $t_{pe}$, of a typical GMC ($M_{\\rm GMC}=9 \\times 10^{4}\\,\\rm{M_{\\odot}}$) is in the range $1-30$ Myr, for gas metallicity $Z=0.05-1\\,\\rm Z_{\\odot}$, respectively. At fixed metallicity, $t_{pe}$ decreases for higher FUV fluxes, $G_0$, due to the larger temperature of the photodissociation region (PDR). The presence of EUV radiation is important at $Z<0.2\\,\\rm{Z_{\\odot}}$, when the size of the HII layer becomes comparable to the cloud radius. We then compute the time-dependent luminosity (for which we give fitting formulae) of several key FIR lines ([CII], ...

  14. The CAMbridge Emission Line Surveyor (CAMELS)

    CERN Document Server

    Thomas, C N; Maiolino, R; Goldie, D J; Acedo, E de Lera; Wagg, J; Blundell, R; Paine, S; Zeng, L

    2014-01-01

    The CAMbridge Emission Line Surveyor (CAMELS) is a pathfinder program to demonstrate on-chip spectrometry at millimetre wavelengths. CAMELS will observe at frequencies from 103-114.7 GHz, providing 512 channels with a spectral resolution of R = 3000. In this paper we describe the science goals of CAMELS, the current system level design for the instrument and the work we are doing on the detailed designs of the individual components. In addition, we will discuss our efforts to understand the impact that the design and calibration of the filter bank on astronomical performance. The shape of the filter channels, the degree of overlap and the nature of the noise all effect how well the parameters of a spectral line can be recovered. We have developed a new and rigorous method for analysing performance, based on the concept of Fisher information. This can in be turn coupled to a detailed model of the science case, allowing design trade-offs to be properly investigated.

  15. Balmer-Dominated Shocks: A Concise Review

    CERN Document Server

    Heng, Kevin

    2009-01-01

    A concise and critical review of Balmer-dominated shocks (BDSs) is presented, summarizing the state of theory and observations, including models with/without shock precursors and their synergy with atomic physics. Observations of BDSs in supernova remnants are reviewed on an object-by-object basis. The relevance of BDSs towards understanding the acceleration of cosmic rays in shocks is emphasized. Probable and possible detections of BDSs in astrophysical objects other than supernova remnants, including pulsar wind nebulae and high-redshift galaxies, are described. The case for the continued future of studying BDSs in astrophysics is made, including their relevance towards understanding electron-ion temperature equilibration in collisionless shocks.

  16. Quantifying correlations between galaxy emission lines and stellar continua

    CERN Document Server

    Beck, Róbert; Yip, Ching-Wa; Szalay, Alexander S; Csabai, István

    2016-01-01

    We analyse the correlations between continuum properties and emission line equivalent widths of star-forming and active galaxies from the Sloan Digital Sky Survey. Since upcoming large sky surveys will make broad-band observations only, including strong emission lines into theoretical modelling of spectra will be essential to estimate physical properties of photometric galaxies. We show that emission line equivalent widths can be fairly well reconstructed from the stellar continuum using local multiple linear regression in the continuum principal component analysis (PCA) space. Line reconstruction is good for star-forming galaxies and reasonable for galaxies with active nuclei. We propose a practical method to combine stellar population synthesis models with empirical modelling of emission lines. The technique will help generate more accurate model spectra and mock catalogues of galaxies to fit observations of the new surveys. More accurate modelling of emission lines is also expected to improve template-base...

  17. Parametric dependence of the line emissions in sonoluminescence

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on a series of spectral measurements of sonoluminescence, this paper investigates parametric dependence of the line emissions in single bubble sonoluminescence (SBSL) and multi-bubble sonoluminescence (MBSL). The experiments show that the intensities of the OH* radical line, the sodium line and the noble gas lines in SBSL are relevant to the driving pressure of the acoustic field and the concentration of the noble gases dissolved in host liquids. The intensity of line emissions in total spectrum increases with the decreasing driving pressure and the increasing concentration of noble gases. Parametric dependence of line emissions in MBSL consists with that in SBSL. Line emissions in sonoluminescence should correspond to lower temperature inside the bubbles. SBSL and MBSL share the same spectral structure, and the difference between them found by previous experiments should result from the different temperatures inside bubbles.

  18. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.;

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...

  19. Iron emission line from the spiral galaxy M101

    CERN Document Server

    Yamauchi, Shigeo

    2015-01-01

    Archival Suzaku data of the face-on spiral galaxy M101 were analyzed. An intense emission line at 6.72^{+0.10}_{-0.12} keV was detected in the central region. This line is identified with a K-line from He-like iron, which indicates the existence of a thin thermal plasma with a temperature of several keV. The iron line luminosity within the central 5 arcmin radius region is estimated to be (2-12)x10^{37} erg s^{-1}. The origin of the iron emission line is discussed.

  20. Emission lines in the long period Cepheid l Carinae

    Science.gov (United States)

    Boehm-Vitense, Erika; Love, Stanley G.

    1991-01-01

    For the Cepheid (l) Carinae with a pulsation period of 35.5 days we have studied the emission line fluxes as a function of pulsational phase in order to find out whether we see chromosphere and transition layer emission or whether we see emission due to an outward moving shock. All emission lines show a steep increase in flux shortly before maximum light suggestive of a shock moving through the surface layers. The large ratio of the C IV to C II line fluxes shows that these are not transition layer lines. During maximum light the large ratio of the C IV to C II line fluxes also suggests that we see emission from a shock with velocities greater than 100 km/sec such that C IV emission can be excited. With such velocities mass outflow appears possible. The variations seen in the Mg II line profiles show that there is an internal absorption over a broad velocity band independent of the pulsational phase. We attribute this absorption to a circumstellar 'shell'. This 'shell' appears to be seen also as spatially extended emission in the O I line at 1300 angstrom, which is probably excited by resonance with Ly beta.

  1. UV-visible emission as a probe of core excitations applied to the furan and carbon dioxide molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kivimaeki, A; Coreno, M; Simone, M de [CNR-INFM, Laboratorio Nazionale TASC, 34149 Trieste (Italy); Ruiz, J Alvarez [Departamento de Quimica Laser, Instituto de Quimica-Fisica Rocasolano Consejo Superior de Investigaciones Cientificas, Serrano 119, 28006 Madrid (Spain); Dampc, M; Zubek, M, E-mail: kivimaki@tasc.infm.i [Department of Physics of Electronic Phenomena, Gdansk University of Technology, Narutowicza 11/12, 80233 Gdansk (Poland)

    2009-11-15

    The core excitations of the furan and carbon dioxide molecules have been studied using dispersed UV-visible fluorescence spectroscopy. Balmer-{alpha} (Balmer-{beta}) emission was measured at the O 1s and C 1s (O 1s) excitations of furan, while emission due to an excited state of the neutral oxygen atom was measured at the O 1s excitations of CO{sub 2}. The excitation functions of the emission lines display both valence and Rydberg resonances, but the latter are more enhanced.

  2. A Guided-Inquiry Lab for the Analysis of the Balmer Series of the Hydrogen Atomic Spectrum

    Science.gov (United States)

    Bopegedera, A. M. R. P.

    2011-01-01

    A guided-inquiry lab was developed to analyze the Balmer series of the hydrogen atomic spectrum. The emission spectrum of hydrogen was recorded with a homemade benchtop spectrophotometer. By drawing graphs and a trial-and-error approach, students discover the linear relationship presented in the Rydberg formula and connect it with the Bohr model…

  3. The Masses of Distant Galaxies from Optical Emission Line Widths

    CERN Document Server

    Gillespie, E B; Gillespie, Elizabeth Barton; Zee, Liese van

    2002-01-01

    Promising methods for studying galaxy evolution rely on optical emission line width measurements to compare intermediate-redshift objects to galaxies with equivalent masses at the present epoch. However, emission lines can be misleading. We show empirical examples of galaxies with concentrated central star formation from a survey of galaxies in pairs; HI observations of these galaxies indicate that the optical line emission fails to sample their full gravitational potentials. We use simple models of bulge-forming bursts of star formation to demonstrate that compact optical morphologies and small half-light radii can accompany these anomalously narrow emission lines; thus late-type bulges forming on rapid (0.5-1 Gyr) timescales at intermediate redshift would exhibit properties similar to those of heavily bursting dwarfs. We conclude that some of the luminous compact objects observed at intermediate and high redshift may be starbursts in the centers of massive galaxies and/or bulges in formation.

  4. Line Emission from Optically Thick RelativisticAccretion Tori

    Energy Technology Data Exchange (ETDEWEB)

    Fuerst, Steven V.; /KIPAC, Menlo Park /Mullard Space Sci. Lab.; Wu, Kinwah; /Mullard Space Sci. Lab.

    2007-09-14

    We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderate viewing inclination angles they both have asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter red peak which has an extensive red wing. At high viewing inclination angles they both have very broad, asymmetric lines which can be roughly considered as single-peaked. Torus and disk lines may show very different red and blue line wings, but the differences are due to the models for relativistic tori and disks having differing inner boundary radii. Self-eclipse and lensing play some role in shaping the torus lines, but they are effective only at high inclination angles. If inner and outer radii of an accretion torus are the same as those of an accretion disk, their line profiles show substantial differences only when inclination angles are close to 90{sup o}, and those differences are manifested mostly at the central regions of the lines instead of the wings.

  5. Far infra-red emission lines in high redshift quasars

    CERN Document Server

    Gallerani, Simona

    2012-01-01

    We present Plateau de Bure Interferometer observations of far infra-red emission lines in BRI 0952-0115, a lensed quasar at z=4.4 powered by a super-massive black hole (M_BH=2x10^9 M_sun). In this source, the resolved map of the [CII] emission at 158 micron allows us to reveal the presence of a companion galaxy, located at \\sim 10 kpc from the quasar, undetected in optical observations. From the CO(5-4) emission line properties we infer a stellar mass M*3500 M_sun/yr).

  6. Significant contribution of the Cerenkov line-like radiation to the broad emission lines of quasars

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D. B.; You, J. H. [Institute of Nuclear, Particle, Astronomy and Cosmology, Department of Physics and Astronomy, and Shanghai Key Lab for Particle Physics and Cosmology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Chen, W. P. [Institute of Astronomy and Department of Physics, National Central University, Chung-Li 32054, Taiwan (China); Chen, L., E-mail: dbliu@sjtu.edu.cn, E-mail: dliu@cfa.Harvard.edu [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany)

    2014-01-01

    The Cerenkov line-like radiation in a dense gas (N {sub H} > 10{sup 13} cm{sup –3}) is potentially important in the exploration of the optical broad emission lines of quasars and Seyfert 1 galaxies. With this quasi-line emission mechanism, some long standing puzzles in the study of quasars could be resolved. In this paper, we calculate the power of the Cerenkov line-like radiation in dense gas and compare with the powers of other radiation mechanisms by a fast electron to confirm its importance. From the observed gamma-ray luminosity of 3C 279, we show that the total number of fast electrons is sufficiently high to allow effective operation of the quasi-line emission. We present a model calculation for the luminosity of the Cerenkov Lyα line of 3C 279, which is high enough to compare with observations. We therefore conclude that the broad line of quasars may be a blend of the Cerenkov emission line with the real line produced by the bound-bound transition. A new approach to the absorption of the Cerenkov line is presented with the method of escape probability, which markedly simplifies the computation in the optically thick case. The revised set of formulae for the Cerenkov line-like radiation is more convenient in applications.

  7. H Emission Line Morphologies in Markarian Starburst Galaxies

    Indian Academy of Sciences (India)

    A. Chitre; U. C. Joshi

    2001-06-01

    We present broad band and narrow band H emission line images of a sample of optically selected starburst galaxies from the Markarian lists. The emission line morphology is studied and global properties like luminosities, equivalent widths and star formation rates are derived. The radial distribution of H flux and the EW are determined using concentric aperture photometry on the emission line and the continuum images. H flux is generally found to peak in the nuclear region and fall off outwards. The EW is found to peak off-center in most of the cases implying that though the intensity of emission is maximum at the nucleus, the star formation activity relative to the underlying continuum often peaks away from the center in Markarian starburst galaxies.

  8. Line-of-sight statistical methods for turbulent medium: VCS for emission and absorption lines

    CERN Document Server

    Pogosyan, D

    2009-01-01

    We present an overview of the Velocity Coordinate Spectrum (VCS), a new technique for studying astrophysical turbulence that utilizes the line-of-sight statistics of Doppler-broadened spectral lines. We consider the retrieval of turbulence spectra from emission intensity observations of both high and low spatial resolution and find that the VCS allows one to study turbulence even when the emitting turbulent volume is not spatially resolved. This opens interesting prospects for using the technique for extragalactic research. VCS developed for spectral emission lines is applicable to absorption lines as well if the optical depth is used instead of intensity. VCS for absorption lines in point-source spectra benefit from effectively narrow beam and does not require dense sky coverage by sampling directions. Even strongly saturated absorption lines still carry the information about the small scale turbulence, albeit limited to the wings of a line. Combining different absorption lines one can develop tomography of ...

  9. Deuterium Balmer/Stark spectroscopy and impurity profiles: first results from mirror-link divertor spectroscopy system on the JET ITER-like wall

    CERN Document Server

    Meigs, A G; Clever, M; Huber, A; Marsen, S; Nicholas, C; Stamp, M; Zastrow, K-D; Contributors, JET EFDA

    2013-01-01

    For the ITER-like wall, the JET mirror link divertor spectroscopy system was redesigned to fully cover the tungsten horizontal strike plate with faster time resolution and improved near-UV performance. Since the ITER-like wall project involves a change in JET from a carbon dominated machine to a beryllium and tungsten dominated machine with residual carbon, the aim of the system is to provide the recycling flux, equivalent, to the impinging deuterium ion flux, the impurity fluxes (C, Be, O) and tungsten sputtering fluxes and hence give information on the tungsten divertor source. In order to do this self-consistently, the system also needs to provide plasma characterization through the deuterium Balmer spectra measurements of electron density and temperature during high density. L-Mode results at the density limit from Stark broadening/line ratio analysis will be presented and compared to Langmuir probe profiles and 2D-tomography of low-n Balmer emission [1]. Comparison with other diagnostics will be vital fo...

  10. Quantifying correlations between galaxy emission lines and stellar continua

    Science.gov (United States)

    Beck, Róbert; Dobos, László; Yip, Ching-Wa; Szalay, Alexander S.; Csabai, István

    2016-03-01

    We analyse the correlations between continuum properties and emission line equivalent widths of star-forming and active galaxies from the Sloan Digital Sky Survey. Since upcoming large sky surveys will make broad-band observations only, including strong emission lines into theoretical modelling of spectra will be essential to estimate physical properties of photometric galaxies. We show that emission line equivalent widths can be fairly well reconstructed from the stellar continuum using local multiple linear regression in the continuum principal component analysis (PCA) space. Line reconstruction is good for star-forming galaxies and reasonable for galaxies with active nuclei. We propose a practical method to combine stellar population synthesis models with empirical modelling of emission lines. The technique will help generate more accurate model spectra and mock catalogues of galaxies to fit observations of the new surveys. More accurate modelling of emission lines is also expected to improve template-based photometric redshift estimation methods. We also show that, by combining PCA coefficients from the pure continuum and the emission lines, automatic distinction between hosts of weak active galactic nuclei (AGNs) and quiescent star-forming galaxies can be made. The classification method is based on a training set consisting of high-confidence starburst galaxies and AGNs, and allows for the similar separation of active and star-forming galaxies as the empirical curve found by Kauffmann et al. We demonstrate the use of three important machine learning algorithms in the paper: k-nearest neighbour finding, k-means clustering and support vector machines.

  11. Infrared [Fe II] Emission Lines from Radiative Atomic Shocks

    CERN Document Server

    Koo, Bon-Chul; Kim, Hyun-Jeong

    2016-01-01

    [Fe II] emission lines are prominent in the infrared (IR), and they are important diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We first review general characteristics of IR [Fe II] emission lines from shocked gas, and derive [Fe II] line fluxes as a function of shock speed and ambient density. We have compiled the available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We find that the observed ratios of IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid-infrared lines, e.g., [Fe II] 35.35 um/[Fe II] 25.99 um, [Fe II] 5.340 um/[Fe II] 25.99 um, and [Fe II] 5.340 um/[Fe II] 17.94 um, are significantly offset from our model grid. We discuss ...

  12. The VLT-FLAMES Tarantula survey XX. The nature of the X-ray bright emission line star VFTS 399

    CERN Document Server

    Clark, J S; Broos, P S; Townsley, L K; Taylor, W D; Walborn, N R; Bird, A J; Sana, H; de Mink, S E; Dufton, P L; Evans, C J; Langer, N; Apellániz, J Maíz; Schneider, F R N; Soszyński, I

    2015-01-01

    The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity - in this study we aim to determine its physical nature and the cause of this behaviour. We find VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select HeI lines - taken together these suggest an OeBe classification. The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that ...

  13. Line emission from optically thick relativistic accretion tori

    CERN Document Server

    Fuerst, Steven V

    2007-01-01

    We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderate viewing inclination angles they both have asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter red peak which has an extensive red wing. At high viewing inclination angles they both have very broad, asymmetric lines which can be roughly considered single-peaked. Torus and disk lines may show very different red and blue line wings, but the differences are due to the models for relativistic tori and disks having differing inner boundary radii. Self-eclipse and lensing play some role in shaping the ...

  14. Two-Component Structure of the Hbeta Broad-Line Region in Quasars. I. Evidence from Spectral Principal Component Analysis

    CERN Document Server

    Hu, Chen; Ho, Luis C; Ferland, Gary J; Baldwin, Jack A; Wang, Ye

    2012-01-01

    We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500--5500 \\AA. The sample is explicitly designed to mitigate spurious effects on SPCA induced by Fe II velocity shifts. We improve the algorithm of SPCA in the literature and introduce a new quantity, \\emph{the fractional-contribution spectrum}, that effectively identifies the emission features encoded in each eigenspectrum. The first eigenspectrum clearly records the power-law continuum and very broad Balmer emission lines. Narrow emission lines dominate the second eigenspectrum. The third eigenspectrum represents the Fe II emission and a component of the Balmer lines with kinematically similar intermediate velocity widths. Correlations between the weights of the eigenspectra and parametric measurements of line strength and continuum slope confirm the above interpretation for the eigenspectra. Monte Carlo simulations demonstr...

  15. GRB hosts through cosmic time - VLT/X-shooter emission-line spectroscopy of 96 GRB-selected galaxies at 0.1 < z < 3.6

    CERN Document Server

    Krühler, T; Fynbo, J P U; Hartoog, O E; Hjorth, J; Jakobsson, P; Perley, D A; Rossi, A; Schady, P; Schulze, S; Tanvir, N R; Vergani, S D; Wiersema, K; Afonso, P M J; Bolmer, J; Cano, Z; Covino, S; D'Elia, V; Postigo, A de Ugarte; Filgas, R; Friis, M; Graham, J F; Greiner, J; Goldoni, P; Gomboc, A; Hammer, F; Japelj, J; Kann, D A; Kaper, L; Klose, S; Levan, A J; Leloudas, G; Milvang-Jensen, B; Guelbenzu, A Nicuesa; Palazzi, E; Pian, E; Piranomonte, S; Sanchez-Ramirez, R; Savaglio, S; Selsing, J; Tagliaferri, G; Vreeswijk, P M; Watson, D J; Xu, D

    2015-01-01

    We present data and initial results from VLT/X-shooter emission-line spectroscopy of 96 GRB-selected galaxies at 0.1Balmer and/or forbidden lines of oxygen, nitrogen and neon, we measure systemic redshifts, star-formation rates, visual attenuations (A_V), oxygen abundances and emission-line widths (sigma). We find a strong change of the typical physical properties of GRB hosts with redshift. The median SFR, for example, increases from ~0.6 M_sun/yr at z~0.6 up to ~15 M_sun/yr at z~2. A higher ratio of [OIII]/[OII] at higher redshifts leads to an increasing distance of GRB-selected galaxies to the locus of local galaxies in the BPT diagram. Oxygen abundances of the galaxies are distributed between 12+log(O/H)=7.9 and 12+log(O/H)=9.0 with a median of 12+log(O/H)~8.5. The fraction of GRB-selected galaxies with super-solar metallic...

  16. Search for an emission line of a gravitational wave background

    CERN Document Server

    Nishizawa, Atsushi

    2015-01-01

    In the light of the history of researches on electromagnetic wave spectrum, a sharp emission line of gravitational-wave background (GWB) would be an interesting observational target. Here we study an efficient method to detect a line GWB by correlating data of multiple ground-based detectors. We find that the width of frequency bin for coarse graining is a critical parameter, and the commonly-used value 0.25 Hz is far from optimal, decreasing the signal-to-noise ratio by up to a factor of seven. By reanalyzing the existing data with a smaller bin width, we might detect a precious line signal from the early universe.

  17. The Subaru FMOS Galaxy Redshift Survey (FastSound). II. The Emission Line Catalog and Properties of Emission Line Galaxies

    CERN Document Server

    Okada, Hiroyuki; Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Ohta, Kouji; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Okumura, Teppei; Shimizu, Ikkoh

    2015-01-01

    We present basic properties of $\\sim$3,300 emission line galaxies detected by the FastSound survey, which are mostly H$\\alpha$ emitters at $z \\sim$ 1.2-1.5 in the total area of about 20 deg$^2$, with the H$\\alpha$ flux sensitivity limit of $\\sim 1.6 \\times 10^{-16} \\rm erg \\ cm^{-2} s^{-1}$ at 4.5 sigma. This paper presents the catalogs of the FastSound emission lines and galaxies, which will be open to the public in the near future. We also present basic properties of typical FastSound H$\\alpha$ emitters, which have H$\\alpha$ luminosities of $10^{41.8}$-$10^{43.3}$ erg/s, SFRs of 20--500 $M_\\odot$/yr, and stellar masses of $10^{10.0}$--$10^{11.3}$ $M_\\odot$. The 3D distribution maps for the four fields of CFHTLS W1--4 are presented, clearly showing large scale clustering of galaxies at the scale of $\\sim$ 100--600 comoving Mpc. Based on 1,105 galaxies with detections of multiple emission lines, we estimate that contamination of non-H$\\alpha$ lines is about 4% in the single-line emission galaxies, which are m...

  18. PROFIT: a new alternative for emission-line PROfile FITting

    CERN Document Server

    Riffel, Rogemar A

    2010-01-01

    I briefly describe a simple routine for emission-line profiles fitting by Gaussian curves or Gauss-Hermite series. The PROFIT (line-PROfile FITting) routine represent a new alternative for use in fits data cubes, as those from Integral Field Spectroscopy or Fabry-Perot Interferometry, and may be useful to better study the emission-line flux distributions and gas kinematics in distinct astrophysical objects, such as the central regions of galaxies and star forming regions. The PROFIT routine is written in IDL language and is available at http://www.ufsm.br/rogemar/software.html. The PROFIT routine was used to fit the [Fe II]1.257um emission-line profiles for about 1800 spectra of the inner 350 pc of the Seyfert galaxy Mrk1066 obtained with Gemini NIFS and shows that the line profiles are better reproduced by Gauss-Hermite series than by the commonly used Gaussian curves. The two-dimensional map of the h_3 Gauss-Hermite moment shows its highest absolute values in regions close to the edge of the radio structure...

  19. Extreme Ultraviolet Emission Lines of Iron Fe XI-XIII

    Science.gov (United States)

    Lepson, Jaan; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Brickhouse, N. S.; Dupree, A. K.

    2013-04-01

    The extreme ultraviolet (EUV) spectral region (ca. 20--300 Å) is rich in emission lines from low- to mid-Z ions, particularly from the middle charge states of iron. Many of these emission lines are important diagnostics for astrophysical plasmas, providing information on properties such as elemental abundance, temperature, density, and even magnetic field strength. In recent years, strides have been made to understand the complexity of the atomic levels of the ions that emit the lines that contribute to the richness of the EUV region. Laboratory measurements have been made to verify and benchmark the lines. Here, we present laboratory measurements of Fe XI, Fe XII, and Fe XIII between 40-140 Å. The measurements were made at the Lawrence Livermore electron beam ion trap (EBIT) facility, which has been optimized for laboratory astrophysics, and which allows us to select specific charge states of iron to help line identification. We also present new calculations by the Hebrew University - Lawrence Livermore Atomic Code (HULLAC), which we also utilized for line identification. We found that HULLAC does a creditable job of reproducing the forest of lines we observed in the EBIT spectra, although line positions are in need of adjustment, and line intensities often differed from those observed. We identify or confirm a number of new lines for these charge states. This work was supported by the NASA Solar and Heliospheric Program under Contract NNH10AN31I and the DOE General Plasma Science program. Work was performed in part under the auspices of the Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC52-07NA27344.

  20. Plasma simulations of emission line regions in high energy environments

    Science.gov (United States)

    Richardson, Chris T.

    This dissertation focuses on understanding two different, but in each case extreme, astrophysical environments: the Crab Nebula and emission line galaxies. These relatively local objects are well constrained by observations and are test cases of phenomena seen at high-z where detailed observations are rare. The tool used to study these objects is the plasma simulation code known as Cloudy. The introduction provides a brief summary of relevant physical concepts in nebular astrophysics and presents the basic features and assumptions of Cloudy. The first object investigated with Cloudy, the Crab Nebula, is a nearby supernova remnant that previously has been subject to photoionization modeling to reproduce the ionized emission seen in the nebula's filamentary structure. However, there are still several unanswered questions: (1) What excites the H2 emitting gas? (2) How much mass is in the molecular component? (3) How did the H2 form? (4) What is nature of the dust grains? A large suite of observations including long slit optical and NIR spectra over ionized, neutral and molecular gas in addition to HST and NIR ground based images constrain a particularly bright region of H2 emission, Knot 51, which exhibits a high excitation temperature of ˜3000 K. Simulations of K51 revealed that only a trace amount of H2 is needed to reproduce the observed emission and that H2 forms through an uncommon nebular process known as associative detachment. The final chapters of this dissertation focus on interpreting the narrow line region (NLR) in low-z emission line galaxies selected by a novel technique known as mean field independent component analysis (MFICA). A mixture of starlight and radiation from an AGN excites the gas present in galaxies. MFICA separates galaxies over a wide range of ionization into subsets of pure AGN and pure star forming galaxies allowing simulations to reveal the properties responsible for their observed variation in ionization. Emission line ratios can

  1. Interpreting the Ionization Sequence in AGN Emission-Line Spectra

    CERN Document Server

    Richardson, Chris T; Baldwin, Jack A; Hewett, Paul C; Ferland, Gary J

    2013-01-01

    We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow lined active galactic nuclei (AGN). Mean field independent component analysis identifies examples of individual SDSS galaxies whose spectra are not dominated by emission due to star formation (SF), which we designate as AGN. We assembled high S/N ratio composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line regions (NLR), extending down to very low-ionization cases. We used a local optimally emitting cloud (LOC) model to fit emission-line ratios in this AGN sequence. These included the weak lines that can be measured only in the co-added spectra, providing consistency checks on strong line diagnostics. After integrating over a wide range of radii and densities our models indicate that the radial extent of the NLR is the major parameter in determining the position of high to moderate ionization AGN along our sequence, providing a physical interpretation for their ...

  2. Typing Supernova Remnants Using X-ray Line Emission Morphologies

    CERN Document Server

    Lopez, Laura A; Badenes, Carles; Huppenkothen, Daniela; Jeltema, Tesla E; Pooley, David A

    2009-01-01

    We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in seventeen Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using power ratios), we find that the core-collapse SNRs are statistically more asymmetric than the Type Ia SNRs. We show that the two classes of supernovae can be separated naturally using this technique because X-ray line morphologies reflect the distinct explosion mechanisms and structure of the circumstellar material. These findings are consistent with recent spectropolarimetry results showing that core-collapse SNe are intrinsically more asymmetric.

  3. Emission-Line Profiles of Accretion Disks with a Non-Axisymmetric Pattern

    OpenAIRE

    SANBUICHI, Kiyotaka; FUKUE, Jun; Kojima, Yasufumi

    1994-01-01

    In several cases, accretion disks may have non-axisymmetric patterns, such as one-armed oscillations and spiral shock waves. In such cases the line emissivity may also become non-axisymmetric. We examined the emission-line profiles for geometrically thin/thick, (non-) relativistic accretion disks while taking acount of the non-axisymmetric emissivity. The emission-line profiles were calculated numerically using a code based on the ray-tracing method. The emission-line profiles are usually ...

  4. The broad emission-line region: the confluence of the outer accretion disc with the inner edge of the dusty torus

    Science.gov (United States)

    Goad, M. R.; Korista, K. T.; Ruff, A. J.

    2012-11-01

    We have investigated the observational characteristics of a class of broad emission line region (BLR) geometries that connect the outer accretion disc with the inner edge of the dusty toroidal obscuring region (TOR). We suggest that the BLR consists of photoionized gas of densities which allow for efficient cooling by ultraviolet (UV)/optical emission lines and of incident continuum fluxes which discourage the formation of grains, and that such gas occupies the range of distance and scale height between the continuum-emitting accretion disc and the dusty TOR. As a first approximation, we assume a population of clouds illuminated by ionizing photons from the central source, with the scale height of the illuminated clouds growing with increasing radial distance, forming an effective surface of a 'bowl'. Observer lines of sight which peer into the bowl lead to a Type 1 active galactic nuclei (AGN) spectrum. We assume that the gas dynamics are dominated by gravity, and we include in this model the effects of transverse Doppler shift (TDS), gravitational redshift (GR) and scale-height-dependent macroturbulence. Our simple model reproduces many of the commonly observed phenomena associated with the central regions of AGN, including (i) the shorter than expected continuum-dust delays (geometry), (ii) the absence of response in the core of the optical recombination lines on short time-scales (geometry/photoionization), (iii) an enhanced redwing response on short time-scales (GR and TDS), (iv) the observed differences between the delays for high- and low-ionization lines (photoionization), (v) identifying one of the possible primary contributors to the observed line widths for near face-on systems even for purely transverse motion (GR and TDS), (vi) a mechanism responsible for producing Lorentzian profiles (especially in the Balmer and Mg II emission lines) in low-inclination systems (turbulence), (vii) the absence of significant continuum-emission-line delays between the

  5. Polarization Diagnostics for Cool Core Cluster Emission Lines

    CERN Document Server

    Sparks, William B; Carswell, Robert F; Voit, G Mark; Donahue, Megan; Cracraft, Misty; Meyer, Eileen T; Hough, James H; Manset, Nadine

    2013-01-01

    The nature of the interaction between low-excitation gas filaments at ~10^4 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ~10^7 K in the centers of galaxy clusters remains a puzzle. The presence of a strong, empirical correlation between the two gas phases is indicative of a fundamental relationship between them, though as yet of undetermined cause. The cooler filaments, originally thought to have condensed from the hot gas, could also arise from a merger or the disturbance of cool circumnuclear gas by nuclear activity. Here, we have searched for intrinsic line emission polarization in cool core galaxy clusters as a diagnostic of fundamental transport processes. Drawing on developments in solar astrophysics, direct energetic particle impact induced polarization holds the promise to definitively determine the role of collisional processes such as thermal conduction in the ISM physics of galaxy clusters, while providing insight into other highly anisotropic excitation mechanisms su...

  6. The MOSDEF Survey: Measurements of Balmer Decrements and the Dust Attenuation Curve at Redshifts z~1.4-2.6

    CERN Document Server

    Reddy, Naveen A; Shapley, Alice E; Freeman, William R; Siana, Brian; Coil, Alison L; Mobasher, Bahram; Price, Sedona H; Sanders, Ryan L; Shivaei, Irene

    2015-01-01

    We present results on the dust attenuation curve of z~2 galaxies using early observations from the MOSFIRE Deep Evolution Field (MOSDEF) survey. Our sample consists of 224 star-forming galaxies with nebular spectroscopic redshifts in the range z= 1.36-2.59 and high S/N measurements of, or upper limits on, the H-alpha and H-beta emission lines obtained with Keck/MOSFIRE. We construct composite SEDs of galaxies in bins of specific SFR and Balmer optical depth in order to directly constrain the dust attenuation curve from the UV through near-IR for typical star-forming galaxies at high redshift. Our results imply an attenuation curve that is very similar to the SMC extinction curve at wavelengths redward of 2500 Angstroms. At shorter wavelengths, the shape of the curve is identical to that of the Calzetti relation, but with a lower normalization (R_V). Hence, the new attenuation curve results in SFRs that are ~20% lower, and log stellar masses that are 0.16 dex lower, than those obtained with the Calzetti attenu...

  7. Warm ionized gas in CALIFA early-type galaxies. 2D emission-line patterns and kinematics for 32 galaxies

    Science.gov (United States)

    Gomes, J. M.; Papaderos, P.; Kehrig, C.; Vílchez, J. M.; Lehnert, M. D.; Sánchez, S. F.; Ziegler, B.; Breda, I.; Dos Reis, S. N.; Iglesias-Páramo, J.; Bland-Hawthorn, J.; Galbany, L.; Bomans, D. J.; Rosales-Ortega, F. F.; Cid Fernandes, R.; Walcher, C. J.; Falcón-Barroso, J.; García-Benito, R.; Márquez, I.; Del Olmo, A.; Masegosa, J.; Mollá, M.; Marino, R. A.; González Delgado, R. M.; López-Sánchez, Á. R.; Califa Collaboration

    2016-04-01

    traces of localized star formation in the extranuclear component of several of our sample galaxies points to a non-negligible contribution by OB stars to the global ionizing photon budget in ETGs. Additionally, our data again highlight the diversity of ETGs in their gaseous and stellar kinematics. While in one half of our sample, gas and stars show similar (yet not necessarily identical) velocity patterns that are both dominated by rotation along the major galaxy axis, our analysis also documents several cases of kinematical decoupling between gas and stars, or rotation along the minor galaxy axis. We point out that the generally very low (≲1 Å) EW(Hα) of ETGs requires a careful quantitative assessment of potential observational and analysis biases in studies of their wim. With standard emission-line fitting tools, Balmer emission lines become progressively difficult to detect below an EW(Hα) ~ 3 Å, therefore our current understanding of the presence and 2D emission patterns and kinematics of the diffuse wim ETGs may be severely incomplete. We demonstrate that at the typical emission-line detection threshold of ~2 Å in previous studies, most of the extranuclear wim emission in an ETG may evade detection, which could in turn cause ETGs to be classified as entirely gas-devoid systems. Conclusions: This study adds further observational evidence for a considerable heterogeneity among ETGs with regard to the physical properties and 2D kinematics of their extended wim component, and it clearly shows that a comprehensive understanding of these systems requires IFS studies over their entire optical extent.

  8. Relativistic emission lines from accreting black holes - The effect of disk truncation on line profiles

    CERN Document Server

    Müller, A; Mueller, Andreas; Camenzind, Max

    2004-01-01

    Relativistic emission lines generated by thin accretion disks around rotating black holes are an important diagnostic tool for testing gravity near the horizon. The iron K-line is of special importance for the interpretation of the X-ray emission of Seyfert galaxies, quasars and galactic X-ray binary systems. A generalized kinematic model is presented which includes radial drifts and non-Keplerian rotations for the line emitters. The resulting line profiles are obtained with an object-oriented ray tracer operating in the curved Kerr background metric. The general form of the Doppler factor is presented which includes all kinds of poloidal and toroidal motions near the horizon. The parameters of the model include the spin parameter, the inclination, the truncation and outer radius of the disk, velocity profiles for rotation and radial drift, the emissivity profile and a multi-species line-system. The red wing flux is generally reduced when radial drift is included as compared to the pure Keplerian velocity fie...

  9. A Monte Carlo model of auroral hydrogen emission line profiles

    Directory of Open Access Journals (Sweden)

    J.-C. Gérard

    2005-06-01

    Full Text Available Hydrogen line profiles measured from space-borne or ground-based instruments provide useful information to study the physical processes occurring in the proton aurora and to estimate the proton flux characteristics. The line shape of the hydrogen lines is determined by the velocity distribution of H atoms along the line-of-sight of the instrument. Calculations of line profiles of auroral hydrogen emissions were obtained using a Monte Carlo kinetic model of proton precipitation into the auroral atmosphere. In this model both processes of energy degradation and scattering angle redistribution in momentum and charge transfer collisions of the high-energy proton/hydrogen flux with the ambient atmospheric gas are considered at the microphysical level. The model is based on measured cross sections and scattering angle distributions and on a stochastic interpretation of such collisions. Calculations show that collisional angular redistribution of the precipitating proton/hydrogen beam is the dominant process leading to the formation of extended wings and peak shifts in the hydrogen line profiles. All simulations produce a peak shift from the rest line wavelength decreasing with increasing proton energy. These model predictions are confirmed by analysis of ground-based H-β line observations from Poker Flat, showing an anti-correlation between the magnitude of the peak shift and the extent of the blue wing of the line. Our results also strongly suggest that the relative extension of the blue and red wings provides a much better indicator of the auroral proton characteristic energy than the position of the peak wavelength.

  10. Ultraviolet Diagnostics for the Emission Line Gas in Active Galaxies

    CERN Document Server

    Allen, M G; Tsvetanov, Z I

    1998-01-01

    Optical diagnostic diagrams are frequently ambiguous as a test of the photoionization or fast shock models of the narrow line regions of active galaxies. Here, we present a set of UV line ratio diagrams which can discriminate between pure shock and photoionization modes of excitation, and to some extent, also discriminate shocks with ionized precursors from photoionization. These diagrams use relatively bright emission lines and reddening insensitive ratios and provide a practical observational test for separating the excitation mechanisms of the narrow line regions of active galaxies. The most useful diagrams are those involving the various ionization stages of Carbon, [OIII]5007/H-beta vs. CIV 1550/ HeII 1640 and the purely UV ratio pair CII] 2326 / CIII] 1909 vs. CIV 1550 / CIII]909. Temperature sensitive FUV lines CIII 977 and NIII 991 also provide good discriminants. The models are compared to observations of nearby AGN, and also to high redshift objects where the UV lines are shifted into the optical.

  11. Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

    CERN Document Server

    Fausnaugh, M M; Bentz, M C; Denney, K D; De Rosa, G; Peterson, B M; Kochanek, C S; Pogge, R W; Adams, S M; Barth, A J; Beatty, Thomas G; Bhattacharjee, A; Borman, G A; Boroson, T A; Bottorff, M C; Brown, Jacob E; Brown, Jonathan S; Brotherton, M S; Coker, C T; Crawford, S M; Croxall, K V; Eftekharzadeh, Sarah; Eracleous, Michael; Joner, M D; Henderson, C B; Holoien, T W -S; Horne, Keith; Hutchison, T; Kaspi, Shai; Kim, S; King, Anthea L; Li, Miao; Lochhaas, Cassandra; Ma, Zhiyuan; MacInnis, F; Manne-Nicholas, E R; Mason, M; Montuori, Carmen; Mosquera, Ana; Mudd, Dale; Musso, R; Nazarov, S V; Nguyen, M L; Okhmat, D N; Onken, Christopher A; Ou-Yang, B; Pancoast, A; Pei, L; Penny, Matthew T; Poleski, Radoslaw; Rafter, Stephen; Romero-Colmenero, E; Runnoe, Jessie; Sand, David J; Schimoia, Jaderson S; Sergeev, S G; Shappee, B J; Simonian, Gregory V; Somers, Garrett; Spencer, M; Starkey, D; Stevens, Daniel J; Tayar, Jamie; Treu, T; Valenti, Stefano; Van Saders, J; Villanueva, S; Villforth, C; Weiss, Yaniv; Winkler, H; Zhu, W

    2016-01-01

    We present the first results from an optical reverberation mapping campaign executed in 2014, targeting the active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-H$\\beta$ lags, we measure black hole masses for all five targets. We also obtain H$\\gamma$ and He{\\sc ii}\\,$\\lambda 4686$ lags for all objects except 3C 382. The He{\\sc ii}\\,$\\lambda 4686$ lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100--300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

  12. X-ray emission lines from photoionized plasmas

    International Nuclear Information System (INIS)

    Plasma emission codes have become a standard tool for the analysis of spectroscopic data from cosmic X-ray sources. However, the assumption of collisional equilibrium, typically invoked in these codes, renders them inapplicable to many important astrophysical situations, particularly those involving X-ray photoionized nebulae, which are likely to exist in the circumsource environments of compact X-ray sources. X-ray line production in a photoionized plasma is primarily the result of radiative cascades following recombination. Through the development of atomic models of several highly-charged ions, this work extends the range of applicability of discrete spectral models to plasmas dominated by recombination. Assuming that ambient plasma conditions lie in the temperature range 105--106 K and the density range 1011--1016 cm-3, X-ray line spectra are calculated over the wavelength range 5--45 angstrom using the HULLAC atomic physics package. Most of the work focuses on the Fe L-shell ions. Line ratios of the form (3s-2p)/(3d-2p) are shown to characterize the principal mode of line excitation, thereby providing a simple signature of photoionization. At electron densities exceeding 1012 cm-3, metastable state populations in the ground configurations approach their LTE value, resulting in the enrichment of the Fe L-shell recombination spectrum and a set of density-sensitive X-ray line ratios. Radiative recombination continua and emission lines produced selectively by Δn = 0 dielectronic recombination are shown to provide two classes of temperature diagnostics. Because of the extreme overionization, the recombination continua are expected to be narrow (ΔE/E much-lt 1), with ΔE = kT. Dielectronic recombination selectively drives radiative transitions that originate on states with vacancies in the 2s subshell, states that are inaccessible under pure RR population kinetics

  13. Emission Line Astronomy - Coronagraphic Tunable Narrow Band Imaging and Integral Field Spectroscopy. Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to continue our program of emission line astronomy featuring three areas of emphasis: 1) The distribution and nature of high redshift emission line...

  14. Line-integrated emissivity in tokamak plasma radiation diagnostics

    International Nuclear Information System (INIS)

    In tokamak plasma radiation diagnostics, an emissivity profile derived from line-integrated radiation measurement data with Abel inversion or tomographic analysis is averaged over a poloidal cross-section of the plasma chord. The width of this cross-section restricts the spatial resolution of the given diagnostic system. In the cases where the condition for infinitesimal-detector approximation is not satisfied, this width appears to be markedly greater than that defined by the angle viewed from the detector center to the poloidal dimension of an aperture, and the contributions to the detected signal from different points on the given cross-section of the plasma chord are not the same, so the average of the emissivity over the cross-section is a weighted one. In fact, many radiation diagnostic systems on tokamaks do not satisfy the infinitesimal-detector approximation condition. On the basis of the derived explicit formula for the line-integrated emissivity, the relevant questions are discussed in detail

  15. BAT AGN Spectroscopic Survey II: X-ray Emission and High Ionization Optical Emission Lines

    CERN Document Server

    Berney, Simon; Trakhtenbrot, Benny; Ricci, Claudio; Lamperti, Isabella; Schawinski, Kevin; Balokovic, Mislav; Crenshaw, D Michael; Fischer, Travis; Gehrels, Neil; Harrison, Fiona; Hashimoto, Yasuhiro; Ichikawa, Kohei; Mushotzky, Richard; Oh, Kyuseok; Stern, Daniel; Treister, Ezequiel; Ueda, Yoshihiro; Veilleux, Sylvain; Winter, Lisa

    2015-01-01

    We investigate the relationship between X-ray and optical line emission in 340 nearby AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction corrected [O III] and hard X-ray luminosity (14-195 keV) with a [OIII] large scatter (R_Pear = 0.64, sigma = 0.62 dex) and a similarly large scatter with the intrinsic 2-10 keV to [O III] luminosities (RPear=0.63, sigma = 0.63 dex). Correlations of the hard X-ray fluxes with the fluxes of high-ionization narrow lines ([O III], He II, [Ne III] and [Ne V]) are not significantly better than with the low ionization lines (Halpha, [SII]). Factors like obscuration or physical slit size are not found to be a significant part of the large scatter. In contrast, the optical emission lines show much better correlations with each other (sigma = 0.3 dex) than with the X-ray flux. The inherent large scatter questions the common usage of narrow emission lines as AGN bolometric luminosity indicators and suggests that other issues such as geometrical...

  16. Line emission from $\\gamma$-ray burst environments

    CERN Document Server

    Böttcher, M

    1999-01-01

    The time and angle dependent line and continuum emission from a dense torus around a cosmological gamma-ray burst source is simulated, taking into account photoionization, collisional ionization, recombination, and electron heating and cooling due to various processes. The importance of the hydrodynamical interaction between the torus and the expanding blast wave is stressed. Due to the rapid deceleration of the blast wave as it interacts with the dense torus, the material in the torus will be illuminated by a drastically different photon spectrum than observable through a low-column-density line of sight, and will be heated by the hydrodynamical interaction between the blast wave and the torus. A model calculation to reproduce the Fe K-alpha line emission observed in the X-ray afterglow of GRB 970508 is presented. The results indicate that ~ 10^{-4} solar masses of iron must be concentrated in a region of less than 10^{-3} pc. The illumination of the torus material due to the hydrodynamic interaction of the ...

  17. Shocked POststarbust Galaxy Survey. I. Candidate Post-starbust Galaxies with Emission Line Ratios Consistent with Shocks

    Science.gov (United States)

    Alatalo, Katherine; Cales, Sabrina L.; Rich, Jeffrey A.; Appleton, Philip N.; Kewley, Lisa J.; Lacy, Mark; Lanz, Lauranne; Medling, Anne M.; Nyland, Kristina

    2016-06-01

    There are many mechanisms by which galaxies can transform from blue, star-forming spirals, to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent observations of nearby case studies have identified a population of galaxies that quench “quietly.” Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the Oh-Sarzi-Schawinski-Yi (OSSY) measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1067 SPOG candidates (SPOGs*) within z = 0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an “E+A” selection. SPOGs* have a 13% 1.4 GHz detection rate from the Faint Images of the Radio Sky at Twenty Centimeters Survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei (AGNs). SPOGs* also have stronger Na i D absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of

  18. Detection of Broad H$\\alpha$ Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

    CERN Document Server

    Yan, Lin; Ofek, E; Gal-Yam, A; Mazzali, P; Perley, D; Vreeswijk, P; Leloudas, G; de Cia, A; Masci, F; Cenko, S B; Cao, Y; Kulkarni, S R; Nugent, P E; Rebbapragada, Umaa D; Woźniak, P R; Yaron, O

    2015-01-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z=0.3434, with properties similar to SN2007bi. It rises within (83-148)days (rest-frame) to reach a peak bolometric luminosity of 1.3x$10^{44}$erg/s, then decays very slowly at 0.015mag. per day. The measured ejecta velocity is 13000km/s. The inferred explosion characteristics, such as the ejecta mass (67-220$M_\\odot$), the total radiative and kinetic energy ($10^{51}$ & 2x$10^{53}$erg respectively), is typical of SLSN-R events. However, the late-time spectrum taken at +251days reveals a Balmer Halpha emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ~4500km/s and has a ~300km/s blue-ward shift relative to the narrow component. We interpret this broad Halpha emission line as the interaction between the supernova ejecta and a H-rich circumstellar medium (CSM) shell, located at a distance of ~4x$10^{16}$cm from the explosion site. This eje...

  19. Compton wavelength, Bohr radius, Balmer's formula and g-factors

    CERN Document Server

    Heyrovska, R

    2004-01-01

    The Balmer formula for the spectrum of atomic hydrogen is shown to be analogous to that in Compton effect and is written in terms of the difference between the absorbed and emitted wavelengths. The g-factors come into play when the atom is subjected to disturbances (like changes in the magnetic and electric fields), and the electron and proton get displaced from their fixed positions giving rise to Zeeman effect, Stark effect, etc.

  20. Narrowband emission line imaging spectrometry using Savart plates

    Science.gov (United States)

    Maione, Bryan; Brickson, Leandra; Kudenov, Michael; Escuti, Michael

    2016-05-01

    Polarization spatial heterodyne interferometry (PSHI) allows for the development of compact, vibration insensitive, high spectral resolution sensors. Introducing the imaging qualities of a lenslet array extends the advantages of PSHI to imaging interferometers. The use of Savart plates enables a birefringent interferometer that obtains higher spectral resolution with fewer optical aberrations when compared to alternative designs. In this paper, we describe the design, construction, calibration and validation of a narrowband emission line imaging spectrometer (NELIS), based on Savart plates and liquid crystal polarization gratings, along with its associated theoretical model. This sensor is advantageous for spectral imaging in the areas of remote sensing, biomedical imaging and machine vision.

  1. 3D Simulations of line emission from ICF capsules

    International Nuclear Information System (INIS)

    Line emission from ICF implosions can be used to diagnose the temperature of the DT fuel and provides an indication of the distortion in the fuel-pusher interface. 2D simulations have provided valuable insights into the usefulness of argon and titanium dopants as diagnostics of instabilities. Characterizing the effects of drive asymmetries requires 3D modeling with large demands for computer time and memory, necessitating the use of parallel computers. We present the results of some 3D simulations achieved with a code utilizing both shared memory and distributed parallelism. We discuss the code structure and related performance issues

  2. Spatially-resolved dust maps from Balmer decrements in galaxies at z~1.4

    CERN Document Server

    Nelson, Erica June; Momcheva, Ivelina G; Brammer, Gabriel B; Wuyts, Stijn; Franx, Marijn; Schreiber, Natascha M Forster; Whitaker, Katherine E; Skelton, Rosalind E

    2015-01-01

    We derive average radial gradients in the dust attenuation towards HII regions in 609 galaxies at z~1.4, using measurements of the Balmer decrement out to r~3kpc. The Balmer decrements are derived from spatially resolved maps of Halpha and Hbeta emission from the 3D-HST survey. We find that with increasing stellar mass (M) both the normalization and strength of the gradient in dust attenuation increases. Galaxies with a mean mass of = 9.2Msun have little dust attenuation at all radii, whereas galaxies with = 10.2Msun have dust attenuation toward Halpha A(Halpha)~2mag in their central regions. We parameterize this as A(Halpha) = b + c log(r), with b = 0.9 + 1.0 log(M10), c = -1.9 - 2.2 log(M10), r in kpc, and M10 the stellar mass in units of 10^10Msun. This expression can be used to correct spatially resolved measurements of Halpha to radial distributions of star formation. When applied to our data, we find that the star formation rates in the central r<1kpc of galaxies in the highest mass bin are ~ 6 Msun...

  3. Photometric classification of emission line galaxies with Machine Learning methods

    CERN Document Server

    Cavuoti, Stefano; D'Abrusco, Raffaele; Longo, Giuseppe; Paolillo, Maurizio

    2013-01-01

    In this paper we discuss an application of machine learning based methods to the identification of candidate AGN from optical survey data and to the automatic classification of AGNs in broad classes. We applied four different machine learning algorithms, namely the Multi Layer Perceptron (MLP), trained respectively with the Conjugate Gradient, Scaled Conjugate Gradient and Quasi Newton learning rules, and the Support Vector Machines (SVM), to tackle the problem of the classification of emission line galaxies in different classes, mainly AGNs vs non-AGNs, obtained using optical photometry in place of the diagnostics based on line intensity ratios which are classically used in the literature. Using the same photometric features we discuss also the behavior of the classifiers on finer AGN classification tasks, namely Seyfert I vs Seyfert II and Seyfert vs LINER. Furthermore we describe the algorithms employed, the samples of spectroscopically classified galaxies used to train the algorithms, the procedure follow...

  4. Bloated stars as agn broad line clouds the emission line spectrum

    CERN Document Server

    Alexander, T; Tal Alexander; Hagai Netzer

    1994-01-01

    The `Bloated Stars Scenario' proposes that AGN broad line emission originates in the winds or envelopes of bloated stars (BS). Its main advantage over BLR cloud models is the gravitational confinement of the gas and its major difficulty the large estimated number of BSs and resulting high mass loss rate. We calculate the emission line spectrum by a detailed numerical photoionization code for a wide range of wind structures and a detailed QSO nucleus model with L(ion)=7E45 erg/s, M(bh)=8E7 Mo. The size and boundary density of the BS wind are determined by various processes: Comptonization by the central continuum source, calculated self consistently, tidal disruption by the black hole and the limit set by the wind's finite mass. We find that the emission spectrum is mainly determined by the conditions at the boundary of the line emitting fraction of the wind rather than by its internal structure. Comptonization results in very high ionization parameters at the boundary which produces an excess of unobserved br...

  5. Estimation of relativistic accretion disk parameters from iron line emission

    CERN Document Server

    Pariev, V I; Miller, W A; Pariev, Vladimir I.; Bromley, Benjamin C.; Miller, Warner A.

    2000-01-01

    The observed iron K-alpha fluorescence lines in Seyfert-1 galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the emission. Here we present an analysis of the geometrical and kinematic properties of the disk based on the extreme frequency shifts of a line profile as determined by measurable flux in both the red and blue wings. The edges of the line are insensitive to the distribution of the X-ray flux over the disk, and hence provide a robust alternative to profile fitting of disk parameters. Our approach yields new, strong bounds on the inclination angle of the disk and the location of the emitting region. We apply our method to interpret observational data from MCG-6-30-15 and find that the commonly assumed inclination 30 deg for the accretion disk in MCG-6-30-15 is inconsistent with the position of the blue edge of the line at a 3 sigma level. A thick turbulent disk model or the presence of highly ionized iron may reconcile the bounds on inclination from the...

  6. Gaseous versus Stellar Velocity Dispersion in Emission-Line Galaxies

    Institute of Scientific and Technical Information of China (English)

    Xiao-Yan Chen; Cai-Na Hao; Jing Wang

    2008-01-01

    We compare the ionized gas velocity dispersion σgas with the stellar velocity dis-persion σ* in star-forming galaxies, composite galaxies, Low Ionization Nuclear Emission-line Regions (LINERs) and Seyfert 2s, compiled from a cross-identification of Sloan Digital Sky Survey Fourth Data Release (SDSS DR4) and Point Source Catalogue Redshift Survey (PSCz). We measure σgas from the FWHMs of emission lines (Hα, [NII]λλ6548, 6583 and [SII] λλ6716, 6731). A significant correlation between the gas and stellar velocity dispersion exists, despite substantial scatter. The mean value of the gas to stellar velocity dispersion ratio is close to unity. This suggests that gas velocity dispersion can substitute for the stellar veloc-ity dispersion as a tracer of the gravitational potential well for all the four types of galaxies,but the involved uncertainties are different from type to type. We also studied σgas/σ* as a function of the redshift and the axial ratio to test the effects of aperture and galaxy inclina-tion, and found that both effects are weak. Finally we checked the trend of σgas/σ* with the infrared luminosity and found no significant correlation.

  7. Neutral Hydrogen and its Emission Lines in the Solar Corona

    CERN Document Server

    Vial, Jean-Claude

    2016-01-01

    Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisionnal and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun cente...

  8. Nitrogen line spectroscopy of O-stars -- I. Nitrogen III emission line formation revisited

    CERN Document Server

    Gonzalez, Jorge G Rivero; Najarro, Francisco

    2011-01-01

    This is the first paper in a series dealing with optical Nitrogen spectroscopy of O-type stars, aiming at the analysis of Nitrogen abundances. We implemented a new Nitrogen model atom into the NLTE atmosphere/spectrum synthesis code FASTWIND, and compare the resulting optical NIII lines at 4634/40/42 A with other predictions, mostly from Mihalas & Hummer (1973, ApJ 179, 827,`MH'), and from the alternative code CMFGEN. Using similar model atmospheres as MH (not blanketed and wind-free), we are able to reproduce their results, in particular the triplet emission lines. According to MH, these should be strongly related to dielectronic recombination (DR) and the drain by certain two-electron transitions. However, using realistic, fully line-blanketed atmospheres at solar abundances, the key role of DR controlling these emission features is superseded -- for O-star conditions -- by the strength of the stellar wind and metallicity. In the case of wind-free models, the resulting lower ionizing EUV-fluxes severely...

  9. Quasar emission lines, radio structures and radio unification

    CERN Document Server

    Jackson, Neal

    2012-01-01

    Unified schemes of radio sources, which account for different types of radio AGN in terms of anisotropic radio and optical emission, together with different orientations of the ejection axis to the line of sight, have been invoked for many years. Recently, large samples of optical quasars, mainly from the Sloan Digital Sky Survey, together with large radio samples, such as FIRST, have become available. These hold the promise of providing more stringent tests of unified schemes but, compared to previous samples, lack high resolution radio maps. Nevertheless they have been used to investigate unified schemes, in some cases yielding results which appear inconsistent with such theories. Here we investigate using simulations how the selection effects to which such investigations are subject can influence the conclusions drawn. In particular, we find that the effects of limited resolution do not allow core-dominated radio sources to be fully represented in the samples, that the effects of limited sensitivity system...

  10. A sensitive search for methanol line emission toward evolved stars

    CERN Document Server

    Gomez, J F; Suarez, O; Rizzo, J R; de Gregorio-Monsalvo, I

    2014-01-01

    We present a sensitive search for methanol line emission in evolved stars at 1 cm, aiming to detect, for the first time, methanol masers in this type of objects. Our sample comprised post-AGB stars and young planetary nebulae (PNe), whose mass-loss processes and circumstellar structures resemble those of young stellar objects (YSOs), where methanol masers are detected. Class I masers were searched for in 73 objects, whereas Class II ones were searched in 16. No detection was obtained. The non-detection of Class I methanol masers indicated that methanol production in dust grains and/or the enhancement of its gas-phase abundance in the shocked regions of evolved objects are not as efficient as in YSOs. We suggest that relatively more evolved PNe might have a better probability of harboring Class II masers.

  11. A versatile apparatus for on-line emission channeling experiments

    CERN Document Server

    da Silva, Manuel Ribeiro; Correia, João Guilherme; Amorim, Lígia Marina; Pereira, Lino Miguel da Costa

    2013-01-01

    The concept and functionality of an apparatus dedicated to emission channeling experiments using short-lived isotopes on-line at ISOLDE/CERN is described. The setup is assembled in two functional blocks - (a) base stand including beam collimation, implantation and measurement chamber, cryogenic extension, and vacuum control system and - (b) Panmure goniometer extension including maneuvering cradle and sample heating furnace. This setup allows for in situ implantation and sample analysis in the as-implanted state and upon cooling down to 50 K and during annealing up to 1200 K. The functionality of the setup will be illustrated with the example of establishing the lattice location of $^{56}$Mn probes implanted into GaAs.

  12. Using optical lines to study particle acceleration at supernova remnants

    Energy Technology Data Exchange (ETDEWEB)

    Morlino, Giovanni [APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13 (France); Department of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States)

    2014-11-15

    The shocks of several young supernova remnants (SNR) are often associated with very thin optical filaments dominated by Balmer emission resulting from charge-exchange and collisional excitation between neutral Hydrogen from the interstellar medium and shocked protons and electrons. Optical lines are a direct probe of the conditions at the shock, in particular the width of the narrow and broad components reflect the temperature upstream and downstream of the shock, respectively. When the shock accelerate efficiently non-thermal particles, the shock structure changes producing anomalous Balmer lines and it is possible to use their line shape and their spatial profile to check the efficiency of SNR shocks in accelerating cosmic rays. Here we illustrate the kinetic theory of shock acceleration in presence of neutrals with some applications to young SNRs. We show that in three cases (RCW 86, SNR 0509-67.5 and Tycho) anomalous Balmer lines can be explained assuming that a fraction of ∼ 10% of the total shock kinetic energy is converted into not thermal particles, while in one single case, the northwestern part of SN 1006, there is no evidence of efficient acceleration.

  13. Influence of the plasma boundary on the line-integrated emissivity

    International Nuclear Information System (INIS)

    In tokamak plasma radiation diagnostics, if the width of a detected plasma chord is comparable with the plasma minor radius, the plasma boundary may influence the line-integrated emissivity considerably and make it a weighted integral of the width-averaged emissivity. The explicit formula for the line-integrated emissivity with taking into account the plasma boundary effect is presented

  14. Quasar emission lines, radio structures and radio unification

    Science.gov (United States)

    Jackson, Neal; Browne, I. W. A.

    2013-02-01

    Unified schemes of radio sources, which account for different types of radio active galactic nucleus in terms of anisotropic radio and optical emission, together with different orientations of the ejection axis to the line of sight, have been invoked for many years. Recently, large samples of optical quasars, mainly from the Sloan Digital Sky Survey (SDSS), together with large radio samples, such as Faint Images of the Radio Sky at Twenty cm (FIRST), have become available. These hold the promise of providing more stringent tests of unified schemes but, compared to previous samples, lack high-resolution radio maps. Nevertheless, they have been used to investigate unified schemes, in some cases yielding results which appear inconsistent with such theories. Here we investigate using simulations how the selection effects to which such investigations are subject can influence the conclusions drawn. In particular, we find that the effects of limited resolution do not allow core-dominated radio sources to be fully represented in the samples, that the effects of limited sensitivity systematically exclude some classes of sources and the lack of deep radio data make it difficult to decide to what extent closely separated radio sources are associated. Nevertheless, we conclude that relativistic unified schemes are entirely compatible with the current observational data. For a sample selected from SDSS and FIRST which includes weak-cored triples we find that the equivalent width of the [O III] emission line decreases as core dominance increases, as expected, and also that core-dominated quasars are optically brighter than weak-cored quasars.

  15. X-ray emission lines from inhomogeneous stellar winds

    CERN Document Server

    Oskinova, L M; Hamann, W R

    2004-01-01

    It is commonly adopted that X-rays from O stars are produced deep inside the stellar wind, and transported outwards through the bulk of the expanding matter which attenuates the radiation and affects the shape of emission line profiles. None of the existing models was able to fit the observationed lines consistently. The possible caveat of these models was the assumption of a smooth stellar wind. Motivated by the various evidences that the stellar winds are in fact structured, we present a 2-D numerical model of a stochastic, inhomogeneous wind. Small parcels of hot, X-ray emitting gas are permeated with cool, absorbing wind material which is compressed into thin shell fragments. Wind fragmentation alters the radiative transfer drastically, compared to homogeneous models of the same mass-loss rate. X-rays produced deep inside the wind, which would be totally absorbed in a homogeneous flow, can effectively escape from a fragmented wind. The wind absorption becomes wavelength independent if the individual fragm...

  16. Protoplanetary disk masses from CO isotopologues line emission

    CERN Document Server

    Miotello, Anna; van Dishoeck, Ewine F

    2014-01-01

    One of the methods for deriving disk masses relies on direct observations of the gas, whose bulk mass is in the outer cold ($T\\lesssim30$K) regions. This zone can be well traced by rotational lines of less abundant CO isotopologues, that probe the gas down to the midplane. The total CO gas mass is then obtained with the isotopologue ratios taken to be constant at the elemental isotope values found in the local ISM. This approach is however imprecise, because isotope selective processes are ignored. The aim of this work is an isotopologue selective treatment of CO isotopologues, in order to obtain a more accurate determination of disk masses. The isotope-selective photodissociation, the main process controlling the abundances of CO isotopologues in the CO-emissive layer, is properly treated for the first time in a full disk model (DALI, Bruderer et al. 2012; Bruderer 2013). The chemistry, thermal balance, line and continuum radiative transfer are all considered together with a chemical network that treats $^{1...

  17. NUMERICAL SIMULATIONS OF THE EMISSION-LINE REGIONS OF QUASARS

    Institute of Scientific and Technical Information of China (English)

    Gary J.Ferland

    2001-01-01

    The luninous quasars are the most distant objects we can directly observe. Once understood, their emission lines will measure the quasar's luminosity and the composition of the interstellar medium of the host galaxy. Unfortunately the emitting plasma is far from equilibrium, and its conditions are set by a host of microphysical processes. The equations of statistical and thermal equilibrium must be solved to determine the ionization distribution, level populations, and kinetic temperature as a function of depth. Simultaneously the line and continuum radiative transfer problems are solved to predict the observed spectrum.A complete simulation involves many hundreds of stages of ionization, many thousands of levels, with populations determined by a vast sea of atomic and molecular processes, many with accurate cross sections and rate coefficients only now becoming available. This is a problem at the very forefront of atomic and computational physics. Once complete, we will be able to map out the first generations of stellar processing in the cores of massive galaxies, and directly chart the expansion of the universe when it had an age under a billion years.

  18. An Integral View of Balmer-dominated Shocks in Supernova Remnants

    CERN Document Server

    Nikolić, Sladjana; Heng, Kevin; Kupko, Daniel; Méndez-Abreu, Jairo; Aguerri, J Alfonso L; Serra, Joan Font; Beckman, John

    2013-01-01

    We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 km/s) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution of the instrument enable us to show that the physical characteristics of the shocks exhibit a strong spatial variation over few atomic scale lengths across 133 sky locations. Our results point to the presence of a population of non-thermal protons (10-100 keV) which might well be the seed particles for generating high-energy cosmic rays. We also present observations of Tycho's supernova remnant taken with the narrow-band tunable filter imager OSIRIS at the GTC and the Fabry-Perot interferometer GHaFaS at the WHT to resolve respectively the broad and narrow H\\alpha\\ lines across a large part of the remnant.

  19. Line emissions from sonoluminescence in aqueous solutions of halide salts without noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jinfu, E-mail: liang.shi2007@163.com [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China); School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001 (China); Chen, Weizhong, E-mail: wzchen@nju.edu.cn [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China); Zhou, Chao; Cui, Weicheng; Chen, Zhan [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China)

    2015-02-20

    Line emissions of trivalent terbium (Tb{sup 3+}) ion were observed from single-bubble sonoluminescence (SL) in an aqueous solution of terbium chloride (TbCl{sub 3}) that contained no noble gas. In addition, sodium (Na) lines were observed in multi-bubble SL in aqueous solutions of various halide salts that contained no noble gas. These observations show that the halide ions, such as Cl{sup −}, Br{sup −}, and I{sup −}, help for line emissions as the noble gases. The intensity of a line emission depends on both the chemical species produced by cavitation bubbles and the temperature of SL bubble that responds to the driving ultrasound pressure. With the increase of driving pressure, some line emissions attached to the continuous spectrum may become increasingly clear, while other line emissions gradually become indistinct. - Highlights: • Line emissions of Tb(III) ions were observed without the presence of noble gases. • The halide ions help to generate a line emission during sonoluminescence. • The intensity of a line emission mainly depends on the bubble's temperature. • The definition of a line emission is related to the temperature of caviation bubble and the kind of host liquid.

  20. A catalog of early-type emission-line stars and Hα line profiles from LAMOST DR2

    Science.gov (United States)

    Hou, Wen; Luo, A.-Li; Hu, Jing-Yao; Yang, Hai-Feng; Du, Chang-De; Liu, Chao; Lee, Chien-De; Lin, Chien-Cheng; Wang, Yue-Fei; Zhang, Yong; Cao, Zi-Huang; Hou, Yong-Hui

    2016-09-01

    We present a catalog including 11 204 spectra of 10 436 early-type emission-line stars from LAMOST DR2, among which 9752 early-type emission-line spectra are newly discovered. For these early-type emission-line stars, we discuss the morphological and physical properties of their low-resolution spectra. In this spectral sample, the Hα emission profiles display a wide variety of shapes. Based on the Hα line profiles, these spectra are categorized into five distinct classes: single-peak emission, single-peak emission in absorption, double-peak emission, double-peak emission in absorption, and P-Cygni profiles. To better understand what causes the Hα line profiles, we divide these objects into four types from the perspective of physical classification, which include classical Be stars, Herbig Ae/Be stars, close binaries and spectra contaminated by HΠ regions. The majority of Herbig Ae/Be stars and classical Be stars are identified and separated using a (H-K, K-W1) color-color diagram. We also discuss 31 binary systems that are listed in the SIMBAD on-line catalog and identify 3600 spectra contaminated by HΠ regions after cross-matching with positions in the Dubout-Crillon catalog. A statistical analysis of line profiles versus classifications is then conducted in order to understand the distribution of Hα profiles for each type in our sample. Finally, we also provide a table of 172 spectra with Fe Π emission lines and roughly calculate stellar wind velocities for seven spectra with P-Cygni profiles.

  1. A catalogue of early-type emission-line stars and H{\\alpha} line profiles from LAMOST DR2

    CERN Document Server

    Hou, Wen; Hu, Jingyao; Yang, Haifeng; Du, Changde; Liu, Chao; Lee, Chien-De; Lin, Chien-Cheng; Wang, Yuefei; Zhang, Yong; Cao, Zihuang; Hou, Yonghui

    2016-01-01

    We present a catalogue including 11,204 spectra for 10,436 early-type emission-line stars from LAMOST DR2, among which 9,752 early-type emission-line spectra are newly discovered. For these early-type emission-line stars, we discuss the morphological and physical properties from their low-resolution spectra. In this spectral sample, the H$\\alpha$ emission profiles display a wide variety of shapes. Based on the H$\\alpha$ line profiles, these spectra are categorized into five distinct classes: single-peak emission, single-peak emission in absorption, double-peak emission, double-peak emission in absorption, and P-Cygni profiles. To better understand what causes the H$\\alpha$ line profiles, we divide these objects into four types from the view of physical classification, which include classical Be stars, Herbig Ae/Be stars, close binaries and spectra contaminated by HII regions. The majority of Herbig Ae/Be stars and classical Be stars are identified and separated using the (H-K, K-W1) color-color diagram. We al...

  2. Redshifts of Emission Line Objects in the Hubble Ultra Deep Field

    CERN Document Server

    Xu, C; Malhotra, S; Rhoads, J E; Mobasher, B; Daddi, E; Gronwall, C; Hathi, N P; Panagia, N; Ferguson, H C; Koekemoer, A M; Kümmel, M; Moustakas, L A; Pasquali, A; Alighieri, S S; Vernet, J; Walsh, J R; Windhorst, R; Yan, H; Xu, Chun; Pirzkal, Norbert; Malhotra, Sangeeta; Rhoads, James E.; Mobasher, Bahram; Daddi, Emanuele; Gronwall, Caryl; Hathi, Nimish P.; Panagia, Nino; Ferguson, Henry C.; Koekemoer, Anton M.; Kuemmel, Martin; Moustakas, Leonidas A.; Pasquali, Anna; Alighieri, Sperello di Serego; Vernet, Joel; Walsh, Jeremy R.; Windhorst, Rogier; Yan, Haojing

    2007-01-01

    We present redshifts for 115 emission line objects in the Hubble Ultra Deep Field (HUDF) identified through the GRism ACS Program for Extragalactic Science (GRAPES) project using the slitless grism spectroscopy mode of the ACS Camera on the Hubble Space Telescope (HST). The sample was selected by an emission line search on all extracted 1-dimensional GRAPES spectra. We identify the emission lines using line wavelength ratios where multiple lines are detected in the grism wavelength range (5800A 25 mag). Such emission lines would likely remain undiscovered without our deep survey. The emission line objects fall into 3 categories: 1) Most are low to moderate redshift galaxies (0 < z < 2), including many actively star forming galaxies with strong HII regions; 2) 9 are high redshift (4 < z < 7) Lyman-alpha emitters; and 3) at least 3 are candidate AGNs.

  3. Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

    DEFF Research Database (Denmark)

    Dietrich, M.; Appenzeller, I.; Hamann, F.;

    2003-01-01

    We present observations of 11 high redshift quasars ($3.9 \\la z \\la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chem......We present observations of 11 high redshift quasars ($3.9 \\la z \\la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate...

  4. Plasma Diagnostics Using K-Line Emission Profiles of Argon

    CERN Document Server

    Chen, Yiling; Reinholz, Heidi; Röpke, Gerd

    2014-01-01

    K-line profiles emitted from a warm dense plasma environment are used for diagnostics of Ar droplet plasmas created by high energy laser pulses. We observe temperature gradients within the Ar droplet from cold temperatures of the order of some 10 eV up to higher temperatures of about 170 eV. Non-perturbative wave functions are calculated as well as ionization energies, binding energies and relevant emission energies using a chemical {\\it ab initio} code. The plasma screening is considered within a perturbative approach to the Hamiltonian. The plasma effect influences the many-particle system resulting in energy shifts due to electron-ion and electron-electron interaction. With this approach we get a good reproduction of spectral features that are strongly influenced by ionization and excitation processes within the plasma. Comparing with the widely known FLYCHK code, counting for internal degrees of freedom (bound states) and treating pressure ionization within our quantum statistical approach leads to differ...

  5. Analysis of neutral hydrogenic emission spectra in a tokamak

    Science.gov (United States)

    Ko, J.; Chung, J.; Jaspers, R. J. E.

    2015-10-01

    Balmer-α radiation by the excitation of thermal and fast neutral hydrogenic particles has been investigated in a magnetically confined fusion device, or tokamak, from the Korea Superconducting Tokamak Advanced Research (KSTAR). From the diagnostic point of view, the emission from thermal neutrals is associated with passive spectroscopy and that from energetic neutrals that are usually injected from the outside of the tokamak to the active spectroscopy. The passive spectroscopic measurement for the thermal Balmeremission from deuterium and hydrogen estimates the relative concentration of hydrogen in a deuterium-fueled plasma and therefore, makes a useful tool to monitor the vacuum wall condition. The ratio of hydrogen to deuterium obtained from this measurement qualitatively correlates with the energy confinement of the plasma. The Doppler-shifted Balmer-α components from the fast neutrals features the spectrum of the motional Stark effect (MSE) which is an essential principle for the measurement of the magnetic pitch angle profile. Characterization of this active MSE spectra, especially with multiple neutral beam lines crossing along the observation line of sight, has been done for the guideline of the multi-ion-source heating beam operation and for the optimization of the narrow bandpass filters that are required for the polarimeter-based MSE diagnostic system under construction at KSTAR.

  6. HST Emission Line Galaxies at z ~ 2: Comparing Physical Properties of Lyman Alpha and Optical Emission Line Selected Galaxies

    CERN Document Server

    Hagen, Alex; Behrens, Christoph; Ciardullo, Robin; Gebhardt, Henry S Grasshorn; Gronwall, Caryl; Bridge, Joanna S; Fox, Derek B; Schneider, Donald P; Trump, Jonathan R; Blanc, Guillermo A; Chiang, Yi-Kuan; Chonis, Taylor S; Finkelstein, Steven L; Hill, Gary J; Jogee, Shardha; Gawiser, Eric

    2015-01-01

    We compare the physical and morphological properties of z ~ 2 Lyman-alpha emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z ~ 2 optical emission line galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5 < logM < 10.5), size (0.5 < R < 3.0 kpc), and star-formation rate (~1 < SFR < 100). Remarkably, a comparison of the most commonly used physical and morphological parameters -- stellar mass, half-light radius, UV slope, star formation rate, ellipticity, nearest neighbor distance, star formation surface density, specific star formation rate, [O III] luminosity, and [O III] equivalent width -- reveals no statistically significant differences between the populations. This suggests that the processes and conditions which regulate the escape of Ly-alpha from a z ~ 2 star-forming galaxy do not depend on these quantities. In particular, the lack of dependence on ...

  7. The IPHAS Catalogue of Halpha Emission Line Sources in the Northern Galactic Plane

    CERN Document Server

    Witham, A R; Drew, J E; Greimel, R; Steeghs, D; Gänsicke, B T; Groot, P J; Mampaso, A

    2007-01-01

    We present a catalogue of point-source Halpha emission line objects selected from the INT/WFC Photometric H$\\alpha$ Survey of the Northern Galactic Plane (IPHAS). The catalogue covers the magnitude range 13 13) emission line objects than were previously known in the Milky Way.

  8. Formation of optical lines in black-hole binaries

    CERN Document Server

    Wu, K; Johnston, H; Hunstead, R W; Wu, Kinwah; Soria, Roberto; Johnston, Helen; Hunstead, Richard

    2002-01-01

    The HI Balmer emission lines of black-hole binaries show double-peaked profiles during the high-soft state and the quiescent state. In the high-soft state the profiles are asymmetric with a stronger red peak, but the profiles are symmetric in the quiescent state. We suggest that in the high-soft state the emission lines originate from the temperature-inversion layer caused by irradiative heating of an optically thick accretion disk. Irradiative heating also causes the formation of a disk wind, which mildly absorbs the blue peak of the lines. The double-peaked lines seen in the quiescent state arise from an optically thin disk. In the absence of a disk wind, the lines are unabsorbed and so the symmetry of the line profiles is preserved.

  9. Detection of emission lines from z ~ 3 DLAs towards the QSO J2358+0149

    CERN Document Server

    Srianand, Raghunathan; Noterdaeme, Pasquier; Petitjean, Patrick; Krühler, Thomas; Japelj, Jure; Pâris, Isabelle; Kashikawa, Nobunari

    2016-01-01

    Using VLT/X-shooter we searched for emission line galaxies associated to four damped Lyman-$\\alpha$ systems (DLAs) and one sub-DLA at 2.73=10 per cent. No other emission line is detected from this system. Because the DLA has a small velocity separation from the quasar (~500 km s^{-1}) and the DLA emission is located within a small projected distance ($\\rho<5$ kpc), we also explore the possibility that the Ly$\\alpha$ emission is being induced by the QSO itself. QSO induced Ly$\\alpha$ fluorescence is possible if the DLA is within a physical separation of 340 kpc to the QSO. Detection of stellar continuum light and/or the oxygen emission lines would disfavor this possibility. We do not detect any emission line from the remaining three systems.

  10. Dark matter line emission constraints from NuSTAR observations of the Bullet Cluster

    DEFF Research Database (Denmark)

    Riemer-Sørensen, S.; Wik, D.; Madejski, G.;

    2015-01-01

    Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. We present the first search for dark matter line emission in the range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line...... emission and instead we derive upper limits (95% CL) on the flux, and interpret these constraints in the context of sterile neutrinos and more generic dark matter candidates. NuSTAR does not have the sensitivity to constrain the recently claimed line detection at , but improves on the constraints...... for energies of 10–25 keV....

  11. Dust extinction from Balmer decrements of star-forming galaxies at 0.75

    CERN Document Server

    Domínguez, A; Henry, A L; Scarlata, C; Bedregal, A G; Malkan, M; Atek, H; Ross, N R; Colbert, J W; Teplitz, H I; Rafelski, M; McCarthy, P; Bunker, A; Hathi, N P; Dressler, A; Martin, C L; Masters, D

    2012-01-01

    Spectroscopic observations of Halpha and Hbeta emission lines of 129 star-forming galaxies in the redshift range 0.75Balmer decrement, as a function of Halpha luminosity down to LHa ~ 3 x 10^{41} erg s^{-1}, galaxy stellar mass down to M_{*} ~ 4 x 10^{8} Msun, and rest-frame Halpha equivalent width. The faintest galaxies are five times fainter in Halpha luminosity than galaxies previously studied at z ~ 1.5. We provide empirical relations to correct for the effect of dust extinction in star-forming galaxies as a function of Halpha luminosity and stellar mass. A clear evolution is observed where galaxies of the same Halpha luminosity have lower extinction at higher redshifts, whereas ...

  12. SHORT-TIMESCALE MONITORING OF THE X-RAY, UV, AND BROAD DOUBLE-PEAK EMISSION LINE OF THE NUCLEUS OF NGC 1097

    Energy Technology Data Exchange (ETDEWEB)

    Schimoia, Jaderson S.; Storchi-Bergmann, Thaisa [Instituto de Física, Universidade Federal do Rio Grande do Sul, Campus do Vale, Porto Alegre, RS (Brazil); Grupe, Dirk [Space Science Center, Morehead State University, 235 Martindale Drive, Morehead, KY 40351 (United States); Eracleous, Michael [Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Peterson, Bradley M. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Baldwin, Jack A. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48864 (United States); Nemmen, Rodrigo S. [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, SP 05508-090 (Brazil); Winge, Cláudia, E-mail: silva.schimoia@ufrgs.br [Gemini South Observatory, c/o AURA Inc., Casilla 603, La Serena (Chile)

    2015-02-10

    Recent studies have suggested that the short-timescale (≲ 7 days) variability of the broad (∼10,000 km s{sup –1}) double-peaked Hα profile of the LINER nucleus of NGC 1097 could be driven by a variable X-ray emission from a central radiatively inefficient accretion flow. To test this scenario, we have monitored the NGC 1097 nucleus in X-ray and UV continuum with Swift and the Hα flux and profile in the optical spectrum using SOAR and Gemini-South from 2012 August to 2013 February. During the monitoring campaign, the Hα flux remained at a very low level—three times lower than the maximum flux observed in previous campaigns and showing only limited (∼20%) variability. The X-ray variations were small, only ∼13% throughout the campaign, while the UV did not show significant variations. We concluded that the timescale of the Hα profile variation is close to the sampling interval of the optical observations, which results in only a marginal correlation between the X-ray and Hα fluxes. We have caught the active galaxy nucleus in NGC 1097 in a very low activity state, in which the ionizing source was very weak and capable of ionizing just the innermost part of the gas in the disk. Nonetheless, the data presented here still support the picture in which the gas that emits the broad double-peaked Balmer lines is illuminated/ionized by a source of high-energy photons which is located interior to the inner radius of the line-emitting part of the disk.

  13. A simple formula for the thermal pair annihilation line emissivity

    OpenAIRE

    Svensson, Roland; Larsson, Stefan; Poutanen, Juri

    1996-01-01

    We introduce a simple and convenient fitting formula for the thermal annihilation line from pair plasmas in cosmic sources. The fitting formula is accurate to 0.04\\% and is valid at all photon energies and temperatures of interest. The commonly used Gaussian line profile is not a good approximation for broader lines.

  14. Numerical experiments on the broadening of emission lines formed in a disk

    International Nuclear Information System (INIS)

    The shapes of emission lines formed from a thin, narrow disk inclined to the plane of the sky are investigated. Where the ratio of the velocity of rotation v to the intrinsic line width sigma is greater than about 2.0, the profile may become double-peaked. Where v is comparable to or smaller than 2 sigma, the line is single-peaked. A solid disk always presents a single-peaked profile. Increasing the inclination of the disk to the line of sight increases the width of the line. The differing widths of the emission lines in stars of the same WN subtype may result from differing values of v, sigma, and the inclination of the disk to the plane of the sky. If the disk has a large hole in its middle, the intensity of the emission line is reduced from what it would be for a solid disk or for one with a small hole. 21 refs

  15. Giant Broad Line Regions in Dwarf Seyferts

    CERN Document Server

    Devereux, Nick

    2015-01-01

    High angular resolution spectroscopy obtained with the Hubble Space Telescope (HST) has revealed a remarkable population of galaxies hosting dwarf Seyfert nuclei with an unusually large broad-line region (BLR). These objects are remarkable for two reasons. Firstly, the size of the BLR can, in some cases, rival those seen in the most luminous quasars. Secondly, the size of the BLR is not correlated with the central continuum luminosity, an observation that distinguishes them from their reverberating counterparts. Collectively, these early results suggest that non-reverberating dwarf Seyferts are a heterogeneous group and not simply scaled versions of each other. Careful inspection reveals broad H Balmer emission lines with single peaks, double peaks, and a combination of the two, suggesting that the broad emission lines are produced in kinematically distinct regions centered on the black hole (BH). Because the gravitational field strength is already known for these objects, by virtue of knowing their BH mass, ...

  16. Spatial Correlation between Dust and Hα Emission in Dwarf Irregular Galaxies

    Science.gov (United States)

    Jimmy; Tran, Kim-Vy; Saintonge, Amélie; Accurso, Gioacchino; Brough, Sarah; Oliva-Altamirano, Paola; Salmon, Brett; Forrest, Ben

    2016-07-01

    Using a sample of dwarf irregular galaxies selected from the ALFALFA blind H i-survey and observed using the VIMOS IFU, we investigate the relationship between Hα emission and Balmer optical depth ({τ }{{b}}). We find a positive correlation between Hα luminosity surface density and Balmer optical depth in 8 of 11 at ≥0.8σ significance (6 of 11 at ≥1.0σ) galaxies. Our spaxels have physical scales ranging from 30 to 80 pc, demonstrating that the correlation between these two variables continues to hold down to spatial scales as low as 30 pc. Using the Spearman’s rank correlation coefficient to test for correlation between {{{Σ }}}{{H}α } and {τ }{{b}} in all the galaxies combined, we find ρ =0.39, indicating a positive correlation at 4σ significance. Our low stellar-mass galaxy results are in agreement with observations of emission line regions in larger spiral galaxies, indicating that this relationship is independent of the size of the galaxy hosting the emission line region. The positive correlation between Hα luminosity and Balmer optical depth within spaxels is consistent with the hypothesis that young star-forming regions are surrounded by dusty birth-clouds. Based on VLT service mode observations (Programs 081.B-0649 and 083.B-0662) gathered at the European Southern Observatory, Chile.

  17. Late Spectral Evolution of SN 1987A: II. Line Emission

    OpenAIRE

    Kozma, Cecilia; Fransson, Claes

    1997-01-01

    Using the temperature and ionization calculated in our previous paper, we model the spectral evolution of SN 1987A. The IR-catastrophe is seen in the metal lines as a transition from thermal to non-thermal excitation, most clearly in the [O I] 6300, 6364 lines. The distribution of the different zones, and therefore the gamma-ray deposition, is determined from the line profiles of the most important lines, where possible. We find the total mass of hydrogen-rich gas to be ~7.7 Msun. The helium ...

  18. IFU spectroscopy of 10 early-type galactic nuclei - II. Nuclear emission line properties

    Science.gov (United States)

    Ricci, T. V.; Steiner, J. E.; Menezes, R. B.

    2014-05-01

    Although it is well known that massive galaxies have central black holes, most of them accreting at low Eddington ratios, many important questions still remain open. Among them are the nature of the ionizing source, the characteristics and frequencies of the broad-line region and of the dusty torus. We report observations of 10 early-type galactic nuclei, observed with the Gemini Multi Object Spectrograph in integral field unit mode, installed on the Gemini South telescope, analysed with standard techniques for spectral treatment and compared with results obtained with principal component analysis Tomography (Paper I). We performed spectral synthesis of each spaxel of the data cubes and subtracted the stellar component from the original cube, leaving a data cube with emission lines only. The emission lines were decomposed in multi-Gaussian components. We show here that, for eight galaxies previously known to have emission lines, the narrow-line region can be decomposed in two components with distinct line widths. In addition to this, broad Hα emission was detected in six galaxies. The two galaxies not previously known to have emission lines show weak Hα+[N II] lines. All 10 galaxies may be classified as low-ionization nuclear emission regions in diagnostic diagrams and seven of them have bona fide active galactic nuclei with luminosities between 1040 and 1043 erg s-1. Eddington ratios are always <10-3.

  19. Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1

    CERN Document Server

    Goldstein, G R; Blank, D

    2004-01-01

    High resolution spectral studies were undertaken at orbital phases 0, 0.25 and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra data. We present (a) the first detailed analysis of the multiple strong narrow emission lines present in phase 0.5 (b) an analysis of the absorption of the continuum in phase 0.5, and (c) the first detection of narrow emission and absorption lines in phase 0.25. Multiple fluorescent and H-and He-like emission lines in the band 1.6 - 20 Angstrom in eclipse are partially obscured at phase 0.25 by the X-ray continuum. The phase 0.25 spectrum displays 3 triplets, 2 with a blue-shifted resonance (r) line in absorption and the intercombination (i) and forbidden (f) lines in emission, and shows in absorption other blue-shifted lines seen in emission in eclipse. At phase 0.5 the soft X-ray continuum diminishes revealing an "eclipse-like" spectrum, however line flux values are around 13-fold those in eclipse. We conclude the narrow emission lines in Vela X-1 become app...

  20. Skylab ultraviolet stellar spectra - Emission lines from the Beta Lyrae system

    Science.gov (United States)

    Kondo, Y.; Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Mccluskey, G. E.

    1976-01-01

    Observations of Beta Lyr with the Skylab S-019 ultraviolet objective-prism spectrograph show numerous emission lines in the region from 1400 to 2300 A. Some variations in line strength between phases 0.25 and 0.50 are seen, which probably explain the shallowness of the OAO-2 light curve at 1910 A. Many of the emission lines are probably due to intercombination transitions, thus confirming the concept that the emission is produced by collisional excitation in low-density clouds of hot gas.

  1. Spectroscopic survey of emission-line stars. I. B[e] stars

    CERN Document Server

    Aret, Anna; Šlechta, Miroslav

    2015-01-01

    Emission-line stars are typically surrounded by dense circumstellar material, often in form of rings or disc-like structures. Line emission from forbidden transitions trace a diversity of density and temperature regimes. Of particular interest are the forbidden lines of [O I] {\\lambda}{\\lambda}6300, 6364 and [Ca II] {\\lambda}{\\lambda}7291, 7324. They arise in complementary, high-density environments, such as the inner-disc regions around B[e] supergiants. To study physical conditions traced by these lines and to investigate how common they are, we initiated a survey of emission-line stars. Here, we focus on a sample of nine B[e] stars in different evolutionary phases. Emission of the [O I] lines is one of the characteristics of B[e] stars. We find that four of the objects display [Ca II] line emission: for the B[e] supergiants V1478 Cyg and 3 Pup the kinematics obtained from the [O I] and [Ca II] line profiles agrees with a Keplerian rotating disc scenario; the forbidden lines of the compact planetary nebula ...

  2. Late Spectral Evolution of SN 1987A; 2, Line Emission

    CERN Document Server

    Fransson, C; Fransson, Claes; Kozma, Cecilia

    1997-01-01

    Using the temperature and ionization calculated in our previous paper, we model the spectral evolution of SN 1987A. The IR-catastrophe is seen in the metal lines as a transition from thermal to non-thermal excitation, most clearly in the [O I] 6300, 6364 lines. The distribution of the different zones, and therefore the gamma-ray deposition, is determined from the line profiles of the most important lines, where possible. We find the total mass of hydrogen-rich gas to be ~7.7 Msun. The helium mass derived from the line fluxes is sensitive to assumptions about the degree of redistribution in the line. The mass of the helium dominated zone is consistent with ~1.9 Msun, with a further ~3.9 Msun of helium residing in the hydrogen component. Because of uncertainties in the modeling of the non-thermal excitation of the [O I] lines, the uncertainty in the oxygen mass is considerable. In addition, masses of nitrogen, neon, magnesium, iron and nickel are estimated. The dominant contribution to the line luminosity often...

  3. Laboratory Measurements of the X-ray Line Emission from Neon-like Fe XVII

    Science.gov (United States)

    Brown, G. V.; Beiersdorfer, P.; Chen, H.; Scofield, J. H.; Boyce, K. R.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Gu, M. F.; Kahn, S. M.

    2006-01-01

    We have conducted a systematic study of the dominant x-ray line emission from Fe XVII. These studies include relative line intensities in the optically thin limit, intensities in the presence of radiation from satellite lines from lower charge states of iron, and the absolute excitation cross sections of some of the strongest lines. These measurements were conducted at the Lawrence Livermore National Laboratory electron beam ion trap facility using crystal spectrometers and a NASA-Goddard Space Flight Center microcalorimeter array.

  4. X-ray Emission Lines in GRB Afterglows: Evidence for a Two-component Jet Model

    Institute of Scientific and Technical Information of China (English)

    Wei-Hong Gao; Da-Ming Wei

    2005-01-01

    X-ray emission lines have been observed in X-ray afterglows of several γ-ray bursts (GRBs). It is a major breakthrough for understanding the nature of the progenitors. It has been proposed that the X-ray emission lines can be well explained by the Geometry-Dominated models, but in these models the illuminating angle is much larger than that of the collimated jet of the GRB. For GRB 011211, we have obtained an illuminating angle of about θ~ 45°, while the angle of the GRB jet is only 3.6°. So we propose that the outflow of GRBs with emission lines should have two distinct components: a wide component that illuminates the reprocessing material and produces the emission lines and a narrow one that produces the GRB. Observations show the energy for producing the emission lines is higher than that of the GRB. In this case, when the wide component dominates the afterglows, a bump should appear in the GRB afterglow. For GRB 011211,the bump should occur within 0.05 days of the GRB, which is obviously too early for the observation to catch it. Alongside the X-ray emission lines there should also be a bright emission component between the UV and the soft X-rays. These features can be tested by the Swift satellite in the near future.

  5. Classification and analysis of emission-line galaxies using mean field independent component analysis

    CERN Document Server

    Allen, James T; Richardson, Chris T; Ferland, Gary J; Baldwin, Jack A

    2013-01-01

    We present an analysis of the optical spectra of narrow emission-line galaxies, based on mean field independent component analysis (MFICA). Samples of galaxies were drawn from the Sloan Digital Sky Survey (SDSS) and used to generate compact sets of `continuum' and `emission-line' component spectra. These components can be linearly combined to reconstruct the observed spectra of a wider sample of galaxies. Only 10 components - five continuum and five emission line - are required to produce accurate reconstructions of essentially all narrow emission-line galaxies; the median absolute deviations of the reconstructed emission-line fluxes, given the signal-to-noise ratio (S/N) of the observed spectra, are 1.2-1.8 sigma for the strong lines. After applying the MFICA components to a large sample of SDSS galaxies we identify the regions of parameter space that correspond to pure star formation and pure active galactic nucleus (AGN) emission-line spectra, and produce high S/N reconstructions of these spectra. The phys...

  6. First detection of line emission from the hot interstellar medium with solid state detectors

    Science.gov (United States)

    Schnopper, H. W.; Delvaille, J. P.; Rocchia, R.; Blondel, C.; Cheron, C.; Christy, J. C.; Ducros, R.; Koch, L.; Rothenflug, R.

    1981-01-01

    Previously reported enhanced soft X-ray emission from the North-Galactic Polar region supports the theory of a hot interstellar component. This paper reports the first detection of line emission from the hot interstellar component in the North-Galactic-Polar region. Measurements were made with solid state Si(Li) detectors aboard a spin-stabilized rocket launched from the White Sands Missile Range on March 22, 1980. Two features are clearly present in the low energy portion of the spectrum derived from the data. They correspond to emission lines from C V (300 eV) and C VI (360 eV), and from O VII (560 eV) and O VIII (650 eV). The detection of emission lines coming from these highly stripped ions is direct evidence for the thermal origin of the emission and confirms the presence of a hot (1-million K) component in the interstellar medium.

  7. The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

    CERN Document Server

    León-Tavares, J; Lobanov, A; Valtaoja, E; Arshakian, T G

    2014-01-01

    AGN reverberate when the broad emission lines respond to changes of the ionizing thermal continuum emission. Reverberation measurements have been commonly used to estimate the size of the broad-line region (BLR) and the mass of the central black hole. However, reverberation mapping studies have been mostly performed on radio-quiet sources where the contribution of the jet can be neglected. In radio-loud AGN, jets and outflows may affect substantially the relation observed between the ionizing continuum and the line emission. To investigate this relation, we have conducted a series of multiwavelength studies of radio-loud AGN, combining optical spectral line monitoring with regular VLBI observations. Our results suggest that at least a fraction of the broad-line emitting material can be located in a sub-relativistic outflow ionized by non-thermal continuum emission generated in the jet at large distances (> 1pc) from the central engine of AGN. This finding may have a strong impact on black hole mass estimates ...

  8. Virilization of the Broad Line Region in Active Galactic Nuclei - connection between shifts and widths of broad emission lines

    CERN Document Server

    Jonic, Sanja; Ilic, Dragana; Popovic, Luka C

    2016-01-01

    We investigate the virilization of the emission lines Hbeta and Mg II in the sample of 287 Type 1 Active Galactic Nuclei taken from the Sloan Digital Sky Survey database. We explore the connections between the intrinsic line shifts and full widths at different levels of maximal intensity. We found that: (i) Hbeta seems to be a good virial estimator of black hole masses, and an intrinsic redshift of Hbeta is dominantly caused by the gravitational effect, (ii) there is an anti-correlation between the redshift and width of the wings of the Mg II line, (iii) the broad Mg II line can be used as virial estimator only at 50% of the maximal intensity, while the widths and intrinsic shifts of the line wings can not be used for this purpose.

  9. Herschel observations of FIR emission lines in brightest cluster galaxies

    CERN Document Server

    Edge, A C; Mittal, R; Allen, S W; Baum, S A; Boehringer, H; Bregman, J N; Bremer, M N; Combes, F; Crawford, C S; Donahue, M; Egami, E; Fabian, A C; Hamer, S L; Hatch, N A; Jaffe, W; Johnstone, R M; McNamara, B R; O'Dea, C P; Popesso, P; Quillen, A C; Salome, P; Sarazin, C L; Voit, G M; Wilman, R J; Wise, M W

    2010-01-01

    The question of how much gas cools in the cores of clusters of galaxies has been the focus of many, multiwavelength studies in the past 30 years. In this letter we present the first detections of the strongest atomic cooling lines, [C II], [O I] and [N I] in two strong cooling flow clusters, A1068 and A2597, using Herschel PACS. These spectra indicate that the substantial mass of cold molecular gas (>10^9 Mo) known to be present in these systems is being irradiated by intense UV radiation, most probably from young stars. The line widths of these FIR lines indicate that they share dynamics similar but not identical to other ionised and molecular gas traced by optical, near-infrared and CO lines. The relative brightness of the FIR lines compared to CO and FIR luminosity is consistent with other star-forming galaxies indicating that the properties of the molecular gas clouds in cluster cores and the stars they form are not unusual. These results provide additional evidence for a reservoir of cold gas that is fed...

  10. 40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What permeation emission control requirements apply for fuel lines? 1060.102 Section 1060.102 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND STATIONARY EQUIPMENT...

  11. Modelling line emission of deuterated H3+ from prestellar cores

    Science.gov (United States)

    Sipilä, O.; Hugo, E.; Harju, J.; Asvany, O.; Juvela, M.; Schlemmer, S.

    2010-01-01

    Context. The depletion of heavy elements in cold cores of interstellar molecular clouds can lead to a situation where deuterated forms of H3+ are the most useful spectroscopic probes of the physical conditions. Aims: The aim is to predict the observability of the rotational lines of H2D+ and D2H+ from prestellar cores. Methods: Recently derived rate coefficients for the H3+ + H2 isotopic system were applied to the “complete depletion” reaction scheme to calculate abundance profiles in hydrostatic core models. The ground-state lines of H2D+(o) (372 GHz) and D2H+(p) (692 GHz) arising from these cores were simulated. The excitation of the rotational levels of these molecules was approximated by using the state-to-state coefficients for collisions with H2. We also predicted line profiles from cores with a power-law density distribution advocated in some previous studies. Results: The new rate coefficients introduce some changes to the complete depletion model, but do not alter the general tendencies. One of the modifications with respect to the previous results is the increase of the D3+ abundance at the cost of other isotopologues. Furthermore, the present model predicts a lower H2D+ (o/p) ratio, and a slightly higher D2H+ (p/o) ratio in very cold, dense cores, as compared with previous modelling results. These nuclear spin ratios affect the detectability of the submm lines of H2D+(o) and D2H+(p). The previously detected H2D+ and D2H+ lines towards the core I16293E, and the H2D+ line observed towards Oph D can be reproduced using the present excitation model and the physical models suggested in the original papers.

  12. Data-driven dissection of emission-line regions in Seyfert galaxies

    CERN Document Server

    Villarroel, Beatriz

    2016-01-01

    Indirectly resolving the line-emitting gas regions in distant Active Galactic Nuclei (AGN) requires both high-resolution photometry and spectroscopy (i.e. through reverberation mapping). Emission in AGN originates on widely different scales; the broad-line region (BLR) has a typical radius less than a few parsec, the narrow-line region (NLR) extends out to hundreds of parsecs. But emission also appears on large scales from heated nebulae in the host galaxies (tenths of kpc). We propose a novel, data-driven method based on correlations between emission-line fluxes to identify which of the emission lines are produced in the same kind of emission-line regions. We test the method on Seyfert galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and Galaxy Zoo project. We demonstrate the usefulness of the method on Seyfert-1s and Seyfert-2 objects, showing similar narrow-line regions (NLRs). Preliminary results from comparing Seyfert-2s in spiral and elliptical galaxy hosts suggest that the presenc...

  13. Constraints on the outer radius of the broad emission line region of active galactic nuclei

    CERN Document Server

    Landt, Hermine; Elvis, Martin; Karovska, Margarita

    2014-01-01

    Here we present observational evidence that the broad emission line region (BELR) of active galactic nuclei (AGN) generally has an outer boundary. This was already clear for sources with an obvious transition between the broad and narrow components of their emission lines. We show that the narrow component of the higher-order Paschen lines is absent in all sources, revealing a broad emission line profile with a broad, flat top. This indicates that the BELR is kinematically separate from the narrow emission line region. We use the virial theorem to estimate the BELR outer radius from the flat top width of the unblended profiles of the strongest Paschen lines, Pa alpha and Pa beta, and find that it scales with the ionising continuum luminosity roughly as expected from photoionisation theory. The value of the incident continuum photon flux resulting from this relationship corresponds to that required for dust sublimation. A flat-topped broad emission line profile is produced by both a spherical gas distribution ...

  14. ROTATIONAL LINE EMISSION FROM WATER IN PROTOPLANETARY DISKS

    NARCIS (Netherlands)

    Meijerink, R.; Poelman, D. R.; Spaans, M.; Tielens, A. G. G. M.; Glassgold, A. E.

    2008-01-01

    Circumstellar disks provide the material reservoir for the growth of young stars and for planet formation. We combine a high-level radiative transfer program with a thermal-chemical model of a typical T Tauri star disk to investigate the diagnostic potential of the far-infrared lines of water for pr

  15. Measurement of Plasma Ion Temperature and Flow Velocity from Chord-Averaged Emission Line Profile

    Indian Academy of Sciences (India)

    Xu Wei

    2011-03-01

    The distinction between Doppler broadening and Doppler shift has been analysed, the differences between Gaussian fitting and the distribution of chord-integral line shape have also been discussed. Local ion temperature and flow velocity have been derived from the chord-averaged emission line profile by a chosen-point Gaussian fitting technique.

  16. X-ray Line Emission from the Hot Stellar Wind of theta 1 Ori C

    OpenAIRE

    Schulz, N. S.; Canizares, C. R.; Huenemoerder, D.; Lee, J. C.

    2000-01-01

    We present a first emission line analysis of a high resolution X-ray spectrum of the stellar wind of theta 1 Ori C obtained with the High Energy Transmission grating Spectrometer onboard the Chandra X-ray Observatory. The spectra are resolved into a large number of emission lines from H- and He-like O, Ne, Mg, Si, S, Ar and Fe ions. The He-like Fe XXV and Li-like Fe XXIV appear quite strong indicating very hot emitting regions. From H/He flux ratios, as well as from Fe He/Li emission measure ...

  17. Unidentified emission lines in Jupiter's northern and southern 2 micron aurorae

    International Nuclear Information System (INIS)

    The detection of a number of unidentified emission lines in Jupiter's 2 micron spectral region for both the northern and southern aurorae is reported. Spectra taken as far back as September 1987 show that at least some of these features are long-lived. Some emission features are present in both the aurorae while others appear to reside only in one or the other. Certain emission lines are detected only at low latitudes. Altogether, two or more species besides H2 are inferred. 13 refs

  18. Broad emission lines variability: a window into the heart of AGN

    OpenAIRE

    Ilic, Dragana; Popovic, Luka C.; Shapovalova, Alla I.; Afanasiev, V.L.; V. H. Chavushyan; Burenkov, A.; Kollatschny, W.; Kovacevic, A.

    2016-01-01

    The broad emission lines of active galactic nuclei (AGN) are known to vary both in flux and shape, and are often showing very complex line profiles. They can give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. The BLR is close to the supermassive black hole in AGN and may hold basic information about the formation and fueling of AGN. Here we summarize the results of the line and continuum variability of a ...

  19. CIV Emission Line Properties and Systematic Trends in Quasar Black Hole Mass Estimates

    OpenAIRE

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.

    2016-01-01

    Black-hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z > 2.1, black hole masses are normally derived using the velocity-width of the CIV broad emission line, based on the assumption that the observed velocity-widths arise from virial-induced motions. In many quasars, the CIV-emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced...

  20. Study of Opacity Effects on Emission Lines at EXTRAP T2R RFP

    International Nuclear Information System (INIS)

    We have investigated the influence of opacity on hydrogen (H-α and Ly-β) and Li-like oxygen emission lines from the EXTRAP T2R reversed field pinch. We used the Atomic Data Analysis System (AzDAS) based on the escape factor approximation for radiative transfer to calculate metastable and excited population densities via a collisional-radiative model. Population escape factor, emergent escape factor and modified line profiles are plotted vs. optical depth. The simulated emission line ratios in the density/temperature plane are in good agreement with experimental data for electron density and temperature measurements

  1. Study of Opacity Effects on Emission Lines at EXTRAP T2R RFP

    Science.gov (United States)

    Stancalie, Viorica; Rachlew, Elisabeth

    We have investigated the influence of opacity on hydrogen (H-α and Ly-β) and Li-like oxygen emission lines from the EXTRAP T2R reversed field pinch. We used the Atomic Data Analysis System (AzDAS) based on the escape factor approximation for radiative transfer to calculate metastable and excited population densities via a collisional-radiative model. Population escape factor, emergent escape factor and modified line profiles are plotted vs. optical depth. The simulated emission line ratios in the density/temperature plane are in good agreement with experimental data for electron density and temperature measurements.

  2. Error Estimates for Emission Lines in the Hydrogen and Helium Isosequences

    Science.gov (United States)

    Smith, R. K.; Brickhouse, N. S.

    2000-05-01

    Emission lines from hydrogen and helium isosequence are among the strongest in X-ray spectra; they will soon be used to measure the temperature, density, and equilibrium state of collisionally excited, astrophysical plasmas. We have created a new plasma code, APEC, which calculates the emission from such a plasma. APEC calculates the line emission from the direct electron and proton excitation rate and the radiative and dielectronic recombination rate. We show how different collisional plasma codes give varying emissivities for some strong lines of O VII and Fe XXVI, where direct excitation is the primary effect. This variation is partly due to simple differences in the plasma code. However, the primary reason is that much work remains to be done on experimental and theoretical calculations of the atomic rates. Large (~ 50%) differences exist even for excitation rates for hydrogenic ions.

  3. Modelling line emission of deuterated H_3^+ from prestellar cores

    OpenAIRE

    Sipilä, O.; Hugo, E.; Harju, J.; Asvany, O.; Juvela, M.; Schlemmer, S.

    2009-01-01

    Context: The depletion of heavy elements in cold cores of interstellar molecular clouds can lead to a situation where deuterated forms of H_3^+ are the most useful spectroscopic probes of the physical conditions. Aims: The aim is to predict the observability of the rotational lines of H_2D^+ and D_2H^+ from prestellar cores. Methods: Recently derived rate coefficients for the H_3^+ + H_2 isotopic system were applied to the "complete depletion" reaction scheme to calculate abundance profiles i...

  4. Modelling line emission of deuterated H_3^+ from prestellar cores

    CERN Document Server

    Sipilä, O; Harju, J; Asvany, O; Juvela, M; Schlemmer, S

    2009-01-01

    Context: The depletion of heavy elements in cold cores of interstellar molecular clouds can lead to a situation where deuterated forms of H_3^+ are the most useful spectroscopic probes of the physical conditions. Aims: The aim is to predict the observability of the rotational lines of H_2D^+ and D_2H^+ from prestellar cores. Methods: Recently derived rate coefficients for the H_3^+ + H_2 isotopic system were applied to the "complete depletion" reaction scheme to calculate abundance profiles in hydrostatic core models. The ground-state lines of H_2D^+(o) (372 GHz) and D_2H^+(p) (692 GHz) arising from these cores were simulated. The excitation of the rotational levels of these molecules was approximated by using the state-to-state coefficients for collisions with H_2. We also predicted line profiles from cores with a power-law density distribution advocated in some previous studies. Results: The new rate coefficients introduce some changes to the complete depletion model, but do not alter the general tendencies...

  5. The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines

    CERN Document Server

    Shen, Yue; Denney, Kelly D; Greene, Jenny E; Grier, C J; Ho, Luis C; Peterson, Bradley M; Petitjean, Patrick; Richards, Gordon T; Schneider, Donald P; Tao, Charling; Trump, Jonathan R

    2016-01-01

    Quasar emission lines are often shifted from the systemic velocity due to various dynamical and radiative processes in the line-emitting region. The level of these velocity shifts depends both on the line species and on quasar properties. We study velocity shifts for the line peaks of various narrow and broad quasar emission lines relative to systemic using a sample of 849 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. The coadded (from 32 epochs) spectra of individual quasars have sufficient signal-to-noise ratio (SNR) to measure stellar absorption lines to provide reliable systemic velocity estimates, as well as weak narrow emission lines. The sample also covers a large dynamic range in quasar luminosity (~2 dex), allowing us to explore potential luminosity dependence of the velocity shifts. We derive average line peak velocity shifts as a function of quasar luminosity for different lines, and quantify their intrinsic scatter. We further quantify how well the peak velocit...

  6. Frequency lock of a dye laser emission on iron atomic line top

    International Nuclear Information System (INIS)

    The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

  7. Abell 262 and RXJ0341: Two Brightest Cluster Galaxies with Line Emission Blanketing a Cool Core

    Science.gov (United States)

    Edwards, Louise O. V.; Heng, Renita

    2014-08-01

    Over the last decade, integral field (IFU) analysis of the brightest cluster galaxies (BCGs) in several cool core clusters has revealed the central regions of these massive old red galaxies to be far from dead. Bright line emission alongside extended X-ray emission links nearby galaxies, is superposed upon vast dust lanes and extends out in long thin filaments from the galaxy core. Yet, to date no unifying picture has come into focus, and the activity across systems is currently seen as a grab-bag of possibile emission line mechanisms. Our primary goal is to work toward a consistent picture for why the BCGs seem are undergoing a renewed level of activity. One problem is most of the current data remains focused on mapping the very core of the BCG, but neglects surrounding galaxies. We propose to discover the full extent of line emission in a complementary pair of BCGs. In Abell 262, an extensive dust patch screens large portions of an otherwise smooth central galaxy, whereas RXJ0341 appears to be a double-core dust free BCG. We will map the full extent of the line emission in order to deduce whether the line emission is a product of local interactions, or the large-scale cluster X-ray gas. The narrow band filter set and large FOV afforded by the the Mayall MOSAIC-1 (MOSA) imager allows us to concurrently conduct an emission line survey of both clusters, locating all line emitting members and beginning a search for the effect of the environment of the different regions (outskirts vs. cluster core) out to the virial radius. We will combine our results with publically available data from 2MASS to determine the upper limits on specific star formation in the BCG and other cluster galaxies within the cluster virial radius.

  8. Emission Line Imaging and Spectroscopy of Distant Galaxies

    DEFF Research Database (Denmark)

    Zabl, Johannes Florian

    for the gas surrounding a galaxy. Around some objects the extended Ly αemission is so strong that it can be detected for individual objects. In this thesis extremely deep VLT/XSHOOTER rest-frame far-UV spectroscopy is presented for Himiko, a gigantic Ly α emitter at redshift z = 6.6 or a time when...... the universe was only 6 per cent of its present age. We constrained with our work, which of the possible Ly α producing mechanisms is responsible for the majority of Himiko’s Ly α emission. We conclude that normal Pop II star formation is the most likely explanation. Himiko is a rare object. Yet, recent...... applied a novel NB measurement method to a sample of UltraVISTA NB118 H α emitters, and demonstrate that this technique allows to recover more accurate fluxes. Additionally, the method allows to determine more accurate redshifts. Contemporary NB surveys have a strong focus on searches for Ly α emitters...

  9. A High Fraction of Double-peaked Narrow Emission Lines in Powerful Active Galactic Nuclei

    Science.gov (United States)

    Lyu, Yang; Liu, Xin

    2016-08-01

    One percent of redshift z ˜ 0.1 Active Galactic Nuclei (AGNs) show velocity splitting of a few hundred km s-1 in the narrow emission lines in spatially integrated spectra. Such line profiles have been found to arise from the bulk motion of ionized gas clouds associated with galactic-scale outflows, merging pairs of galaxies each harboring a supermassive black hole (SMBH), and/or galactic-scale disk rotation. It remains unclear, however, how the frequency of narrow-line velocity splitting may depend on AGN luminosity. Here we study the correlation between the fraction of Type 2 AGNs with double-peaked narrow emission lines and AGN luminosity as indicated by [O III]λ5007 emission-line luminosity L[O III]. We combine the sample of Liu et al. (2010a) at z ˜ 0.1 with a new sample of 178 Type 2 AGNs with double-peaked [O III] emission lines at z ˜ 0.5. We select the new sample from a parent sample of 2089 Type 2 AGNs from the SDSS-III/Baryon Oscillation Spectroscopic Survey. We find a statistically significant (˜4.2σ) correlation between L[O III] and the fraction of objects that exhibit double-peaked narrow emission lines among all Type 2 AGNs, corrected for selection bias and incompleteness due to [O III] line width, equivalent width, splitting velocity, and/or equivalent width ratio between the two velocity components. Our result suggests that galactic-scale outflows and/or merging pairs of SMBHs are more prevalent in more powerful AGNs, although spatially resolved follow up observations are needed to resolve the origin(s) for the narrow-line velocity splitting for individual AGNs.

  10. TWO-COMPONENT STRUCTURE OF THE Hβ BROAD-LINE REGION IN QUASARS. I. EVIDENCE FROM SPECTRAL PRINCIPAL COMPONENT ANALYSIS

    International Nuclear Information System (INIS)

    We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500-5500 Å. The sample is explicitly designed to mitigate spurious effects on SPCA induced by Fe II velocity shifts. We improve the algorithm of SPCA in the literature and introduce a new quantity, the fractional-contribution spectrum, that effectively identifies the emission features encoded in each eigenspectrum. The first eigenspectrum clearly records the power-law continuum and very broad Balmer emission lines. Narrow emission lines dominate the second eigenspectrum. The third eigenspectrum represents the Fe II emission and a component of the Balmer lines with kinematically similar intermediate-velocity widths. Correlations between the weights of the eigenspectra and parametric measurements of line strength and continuum slope confirm the above interpretation for the eigenspectra. Monte Carlo simulations demonstrate the validity of our method to recognize cross talk in SPCA and firmly rule out a single-component model for broad Hβ. We also present the results of SPCA for four other samples that contain quasars in bins of larger Fe II velocity shift; similar eigenspectra are obtained. We propose that the Hβ-emitting region has two kinematically distinct components: one with very large velocities whose strength correlates with the continuum shape and another with more modest, intermediate velocities that is closely coupled to the gas that gives rise to Fe II emission.

  11. Two-component Structure of the Hβ Broad-line Region in Quasars. I. Evidence from Spectral Principal Component Analysis

    Science.gov (United States)

    Hu, Chen; Wang, Jian-Min; Ho, Luis C.; Ferland, Gary J.; Baldwin, Jack A.; Wang, Ye

    2012-12-01

    We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500-5500 Å. The sample is explicitly designed to mitigate spurious effects on SPCA induced by Fe II velocity shifts. We improve the algorithm of SPCA in the literature and introduce a new quantity, the fractional-contribution spectrum, that effectively identifies the emission features encoded in each eigenspectrum. The first eigenspectrum clearly records the power-law continuum and very broad Balmer emission lines. Narrow emission lines dominate the second eigenspectrum. The third eigenspectrum represents the Fe II emission and a component of the Balmer lines with kinematically similar intermediate-velocity widths. Correlations between the weights of the eigenspectra and parametric measurements of line strength and continuum slope confirm the above interpretation for the eigenspectra. Monte Carlo simulations demonstrate the validity of our method to recognize cross talk in SPCA and firmly rule out a single-component model for broad Hβ. We also present the results of SPCA for four other samples that contain quasars in bins of larger Fe II velocity shift; similar eigenspectra are obtained. We propose that the Hβ-emitting region has two kinematically distinct components: one with very large velocities whose strength correlates with the continuum shape and another with more modest, intermediate velocities that is closely coupled to the gas that gives rise to Fe II emission.

  12. Spectroscopy of bright quasars: emission lines and internal extinction

    CERN Document Server

    Bachev, R; Semkov, E; Mihov, B

    2008-01-01

    The main purpose of this work is to improve the existing knowledge about the most powerful engines in the Universe - quasars. Although a lot is already known, we still have only a vague idea how these engines work exactly, why they behave as they do, and what the relation is between their evolution and the evolution of their harboring galaxy. Methods we used are based on optical spectroscopy of visually bright quasars, many of which have recently been discovered as X-ray sources, but eventually missed in color-selected surveys. The spectra typically cover the 4200-7000 AA region, allowing measurements of the characteristics of the hydrogen lines, the FeII contribution, and other lines of interest. We present accurate redshift estimates and Seyfert type classification of the objects. We also show that the contribution of the host galaxy to the optical continuum is non-negligible in many cases, as is the intrinsic AGN absorption. Consequences of not correcting for those factors when estimating different quasar ...

  13. Theoretical emission line ratios for O VII in low-density plasmas

    International Nuclear Information System (INIS)

    New electron excitation rates for O VII calculated by Tayal and Kingston using the R-matrix method are used to determine theoretical emission line strengths. Values of the electron density sensitive ratio R (forbidden line to intercombination line) are found to be very similar to those deduced by other authors. However the temperature sensitive ratios G (intercombination plus forbidden lines to resonance line) are approximately 20% lower than the best previous estimates. The observed value of G for solar active regions (G=1.0 +- 0.1) predicts an electron temperature in the range 1.1 x 106 K 6 K, which overlaps that of maximum O VII emissivity, Tsub(M) = 1.8 x 106 K. In addition, the theoretical G versus Tsub(e) curve is an excellent agreement with the observed for a Tokamak plasma. (orig.)

  14. MAPPING DUST THROUGH EMISSION AND ABSORPTION IN NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Kreckel, Kathryn; Groves, Brent; Schinnerer, Eva; Meidt, Sharon E.; Tabatabaei, Fatemeh S. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Johnson, Benjamin D. [Institut d' Astrophysique de Paris, UMR 7095, 98 bis Bvd Arago, F-75014 Paris (France); Aniano, Gonzalo [Institut d' Astrophysique Spatiale (IAS), Batiment 121, Universite Paris-Sud 11 and CNRS (UMR 8617), F-91405 Orsay (France); Calzetti, Daniela [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Croxall, Kevin V. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Draine, Bruce T. [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 (United States); Gordon, Karl D. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Crocker, Alison F.; Smith, J. D. T. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Hunt, Leslie K. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Kennicutt, Robert C., E-mail: kreckel@mpia.de [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-07-01

    Dust has long been identified as a barrier to measuring inherent galaxy properties. However, the link between dust and attenuation is not straightforward and depends on both the amount of dust and its distribution. Herschel imaging of nearby galaxies undertaken as part of the KINGFISH project allows us to map the dust as seen in emission with unprecedented sensitivity and {approx}1 kpc resolution. We present here new optical integral field unit spectroscopy for eight of these galaxies that provides complementary 100-200 pc scale maps of the dust attenuation through observation of the reddening in both the Balmer decrement and the stellar continuum. The stellar continuum reddening, which is systematically less than that observed in the Balmer decrement, shows no clear correlation with the dust, suggesting that the distribution of stellar reddening acts as a poor tracer of the overall dust content. The brightest H II regions are observed to be preferentially located in dusty regions, and we do find a correlation between the Balmer line reddening and the dust mass surface density for which we provide an empirical relation. Some of the high-inclination systems in our sample exhibit high extinction, but we also find evidence that unresolved variations in the dust distribution on scales smaller than 500 pc may contribute to the scatter in this relation. We caution against the use of integrated A{sub V} measures to infer global dust properties.

  15. Gaia-ESO Survey: Gas dynamics in the Carina Nebula through optical emission lines

    CERN Document Server

    Damiani, F; Magrini, L; Prisinzano, L; Mapelli, M; Micela, G; Kalari, V; Apellaniz, J Maiz; Gilmore, G; Randich, S; Alfaro, E; Flaccomio, E; Koposov, S; Klutsch, A; Lanzafame, A C; Pancino, E; Sacco, G G; Bayo, A; Carraro, G; Casey, A R; Costado, M T; Franciosini, E; Hourihane, A; Lardo, C; Lewis, J; Monaco, L; Morbidelli, L; Worley, C; Zaggia, S; Zwitter, T; Dorda, R

    2016-01-01

    We present observations from the Gaia-ESO Survey in the lines of H$\\alpha$, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV $>$50 km/s) gas emission. We show that gas giving rise to H$\\alpha$ and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around $\\eta$ Car, the Trumpler 14...

  16. Luminous HC3N line emission in NGC4418 - buried AGN or nascent starburst?

    CERN Document Server

    Aalto, S; Martin, S

    2007-01-01

    IRAM 30m observations reveal that the deeply obscured IR-luminous galaxy NGC4418 has a rich molecular chemistry - including unusually luminous HC3N line emission. We furthermore detect: ortho-H2CO 2-1, 3-2; CN 1-0, 2-1; HCO+, 1-0. 3-2, HCN 3-2, HNC 1-0, 3-2 (and tentatively OCS 12-11). The HCN, HCO+, H2CO and CN line emission can be fitted to densities of n=5 x 10E4 - 10E5 cm-3 and gas temperatures Tk=80-150 K. Both HNC and HC3N are, however, significantly more excited than the other species which requires higher gas densities - or radiative excitation through e.g. mid-IR pumping. The HCN line intensity is fainter than that of HCO+ and HNC for the 3-2 transition, in contrast to previous findings for the 1-0 lines where the HCN emission is the most luminous. We tentatively suggest that the observed molecular line emission is consistent with a young starburst, where the emission can be understood as emerging from dense, warm gas with an additional PDR component. We find that X-ray chemistry is not required to e...

  17. Identification of Emission Lines in the Low-Ionization Strontium Filament Near Eta Carinae

    CERN Document Server

    Hartman, H; Johansson, S; Smith, N

    2004-01-01

    We have obtained deep spectra from 1640 to 10100A with the Space Telescope Imaging Spectrograph (STIS) of the Strontium Filament, a largely neutral emission nebulosity lying close to the very luminous star Eta Carinae and showing an uncommon spectrum. Over 600 emission lines, both permitted and forbidden, have been identified. The majority originates from neutral or singly-ionized iron group elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Sr is the only neutron capture element detected. The presence of Sr II, numerous strong Ti II and V II lines and the dominance of Fe I over Fe II are notable discoveries. While emission lines of hydrogen, helium, and nitrogen are associable with other spatial structures at other velocities within the Homunculus, no emission lines from these elements correspond to the spatial structure or velocity of the Sr Filament. Moreover, no identified Sr Filament emission line requires an ionization or excitation energy above approximately 8 eV. Ionized gas extends spatially along the apertur...

  18. Physical Conditions in the X-ray Emission-line Gas in NGC 1068

    CERN Document Server

    Kraemer, S B; Turner, T J; George, Ian M; Crenshaw, D Michael

    2014-01-01

    We present a detailed, photoionization modeling analysis of XMM-Newton/Reflection Grating Spectrometer observations of the Seyfert 2 galaxy NGC 1068. The spectrum, previously analyzed by Kinkhabwala et al. (2002), reveals a myriad of soft-Xray emission lines, including those from H- and He-like carbon, nitrogen, oxygen, and neon, and M- and L-shell iron. As noted in the earlier analysis, based on the narrowness of the radiative recombination continua, the electron temperatures in the emission-line gas are consistent with photoionization, rather than collisional ionization. The strengths of the carbon and nitrogen emission lines, relative to those of oxygen, suggest unusual elemental abundances, which we attribute to star-formation history of the host galaxy. Overall, the emission-lines are blue-shifted with respect to systemic, with radial velocities ~ 160 km/s, similar to that of [O III] 5007, and thus consistent with the kinematics and orientation of the optical emission-line gas and, hence, likely part of ...

  19. Broad emission lines variability: a window into the heart of AGN

    Science.gov (United States)

    Ilic, Dragana; Popovic, Luka C.; Shapovalova, Alla I.; Afanasiev, V. L.; Chavushyan, V. H.; Burenkov, A.; Kollatschny, W.; Kovacevic, A.

    2016-08-01

    The broad emission lines of active galactic nuclei (AGN) are known to vary both in flux and shape, and are often showing very complex line profiles. They can give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. The BLR is close to the supermassive black hole in AGN and may hold basic information about the formation and fueling of AGN.Here we summarize the results of the line and continuum variability of a sample of broad line AGN, obtained with the long-term optical monitoring campaign performed with telescopes of SAO (Russia), OAGH and OAN-SPM (Mexico), and Calar Alto (Spain). We monitored different type of broad line AGN (double-peaked, radio loud and radio quiet, NLSy1 and a supermassive binary black hole candidate) which show different variability characteristics that can be explained by different physical properties in BLR.

  20. A High Fraction of Double-peaked Narrow Emission Lines in Powerful Active Galactic Nuclei

    CERN Document Server

    Lyu, Yang

    2016-01-01

    One percent of redshift z~0.1 Active Galactic Nuclei (AGNs) show velocity splitting of a few hundred km/s in the narrow emission lines in spatially integrated spectra. Such line profiles have been found to arise from the bulk motion of ionized gas clouds associated with galactic-scale outflows, merging pairs of galaxies each harboring a supermassive black hole (SMBH), and/or galactic-scale disk rotation. It remains unclear, however, how the frequency of narrow-line velocity splitting may depend on AGN luminosity. Here we study the correlation between the fraction of Type 2 AGNs with double-peaked narrow emission lines and AGN luminosity as indicated by [O III]5007 emission-line luminosity L_[O III]. We combine the sample of Liu et al. (2010) at z~0.1 with a new sample of 178 Type 2 AGNs with double-peaked [O III] emission lines at z~0.5. We select the new sample from a parent sample of 2089 Type 2 AGNs from the SDSS-III/Baryon Oscillation Spectroscopic Survey. We find a statistically significant (~4.2\\sigma) ...

  1. On the Thermal Line Emission from the Outflows in Ultraluminous X-Ray Sources

    Science.gov (United States)

    Xu, Ya-Di; Cao, Xinwu

    2016-08-01

    The atomic features in the X-ray spectra of ultraluminous X-ray sources (ULXs) may be associated with the outflow, which may provide a way to explore the physics of the ULXs. We construct a conical outflow model and calculate the thermal X-ray Fe emission lines from the outflows. Our results show that thermal line luminosity decreases with increasing outflow velocity and/or opening angle of the outflow for a fixed kinetic power of the outflows. Assuming the kinetic power of the outflows to be comparable with the accretion power in the ULXs, we find that the equivalent width can be several eV for the thermal X-ray Fe emission line from the outflows in the ULXs with stellar-mass black holes. The thermal line luminosity is proportional to 1/M bh (M bh is the black hole mass of the ULX). The equivalent width decreases with the black hole mass, which implies that the Fe line emission from the outflows can hardly be detected if the ULXs contain intermediate-mass black holes. Our results suggest that the thermal X-ray Fe line emission should be preferentially be detected in the ULXs with high kinetic power slowly moving outflows from the accretion disks surrounding stellar-mass black holes/neutron stars. The recently observed X-ray atomic features of the outflows in a ULX may imply that it contains a stellar-mass black hole.

  2. Detecting emission lines with XMM-Newton in 4U 1538-52

    CERN Document Server

    Rodes-Roca, J J; Torrejón, J M; Osborne, J P; Bernabéu, G; 10.1051/0004-6361/201014324

    2010-01-01

    Context. The properties of the X-ray emission lines are a fundamental tool for studying the nature of the matter surrounding the neutron star and the phenomena that produce these lines. Aims. The aim of this work is to analyze the X-ray spectrum of 4U 1538-52 obtained by the XMM-Newton observatory and to look for the presence of diagnostic lines in the energy range 0.3-11.5 keV. Methods. We used a 54 ks PN & MOS/XMM-Newton observation of the high mass X-ray binary 4U 1538-52 covering the orbital phase between 0.75 to 1.00 (the eclipse-ingress). We have modelled the 0.3-11.5 keV continuum emission with three absorbed power laws and looked for the emission lines. Results. We found previously unreported recombination lines, in this system, at 2.4 keV, 1.9 keV and 1.3 keV, consistent with the presence of highly ionized states of S XV He?, Si XIII He? and Mg K? or Mg XI He?. On the other hand, both out of eclipse and in eclipse we detect a fluorescence iron emission line at 6.4 keV which is resolved into two c...

  3. Tracing the origins of permitted emission lines in RU Lupi down to AU scales

    CERN Document Server

    Podio, L; Bacciotti, F; Antoniucci, S; Nisini, B; Dougados, C; Takami, M

    2007-01-01

    Most of the observed emission lines and continuum excess from young accreting low mass stars (Classical T Tauri stars -- CTTSs) take place in the star-disk or inner disk region. These regions have a complex emission topology still largely unknown. In this paper the magnetospheric accretion and inner wind contributions to the observed permitted He and H near infrared (NIR) lines of the bright southern CTTS RU Lupi are investigated for the first time. Previous optical observations of RU Lupi showed a large H-alpha profile, due to the emission from a wind in the line wings, and a micro-jet detected in forbidden lines. We extend this analysis to NIR lines through seeing-limited high spectral resolution spectra taken with VLT/ISAAC, and adaptive optics (AO) aided narrow-band imaging and low spectral resolution spectroscopy with VLT/NACO. Using spectro-astrometric analysis we investigate the presence of extended emission down to very low spatial scales (a few AU). The HeI 10830 line presents a P Cygni profile whose...

  4. Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths

    CERN Document Server

    Feltre, Anna; Gutkin, Julia

    2015-01-01

    In the context of observations of the rest-frame ultraviolet and optical emission from distant galaxies, we explore the emission-line properties of photoionization models of active and inactive galaxies. Our aim is to identify new line-ratio diagnostics to discriminate between gas photoionization by active galactic nuclei (AGN) and star formation. We use a standard photoionization code to compute the emission from AGN narrow-line regions and compare this with calculations of the nebular emission from star-forming galaxies achieved using the same code. We confirm the appropriateness of widely used optical spectral diagnostics of nuclear activity versus star formation and explore new diagnostics at ultraviolet wavelengths. We find that combinations of a collisionally excited metal line or line multiplet, such as CIV 1548,1551, OIII]1661,1666, NIII]1750, [SiIII]1883+[SiIII]1892 and [CIII]1907+CIII]1909, with the HeII 1640 recombination line are individually good discriminants of the nature of the ionizing source...

  5. Ly\\alpha\\ emission line reconstruction for high-$z$ QSOs

    CERN Document Server

    Greig, Bradley; McGreer, Ian D; Gallerani, Simona; Haiman, Zoltán

    2016-01-01

    We introduce an intrinsic Ly\\alpha\\ emission line profile reconstruction method for high-$z$ quasars (QSOs). This approach utilises a covariance matrix of emission line properties obtained from a large, moderate-$z$ ($2 \\leq z \\leq 2.5$), high signal to noise (S/N > 15) sample of BOSS QSOs. For each QSO, we complete a Monte Carlo Markov Chain fitting of the continuum and emission line properties and perform a visual quality assessment to construct a large database of robustly fit spectra. With this dataset, we construct a covariance matrix to describe the correlations between the high ionisation emission lines Ly\\alpha, C IV, Si IV + O IV] and C III], and find it to be well approximated by an $N$-dimensional Gaussian distribution. This covariance matrix characterises the correlations between the line width, peak height and velocity offset from systemic while also allowing for the existence of broad and narrow line components for Ly\\alpha\\ and C IV. We illustrate how this covariance matrix allows us to statist...

  6. HI 21 cm Emission Line Study of Southern Galactic Supernova Remnants

    CERN Document Server

    Koo, B C; McClure-Griffiths, N M; Koo, Bon-Chul; Kang, Ji-hyun

    2004-01-01

    We have searched for HI 21 cm line emission from shocked atomic gas associated with southern supernova remnants (SNRs) using data from the Southern Galactic Plane Survey. Among the 97 sources studied, we have detected 10 SNRs with high-velocity HI emission confined to the SNR. The large velocity and the spatial confinement suggest that the emission is likely from the gas accelerated by the SN blast wave. We also detected 22 SNRs which show HI emission significantly brighter than the surrounding regions over a wide ($>10$\\kms) velocity interval. The association with these SNRs is less certain. We present the parameters and maps of the excess emission in these SNRs. We discuss in some detail the ten individual SNRs with associated high-velocity HI emission.

  7. THE CONNECTIONS BETWEEN THE UV AND OPTICAL Fe ii EMISSION LINES IN TYPE 1 AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Kovacević-Dojcinović, Jelena; Popović, Luka Č., E-mail: jkovacevic@aob.bg.ac.rs, E-mail: lpopovic@aob.bg.ac.rs [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

    2015-12-15

    We investigate the spectral properties of the UV (λλ2650–3050 Å) and optical (λλ4000–5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe ii{sub opt}) versus EW [O iii] 5007 Å and EW Fe ii{sub opt} versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  8. Comparison of Fe XVIII and Fe XIX Line Emissions with Spectral Models

    Science.gov (United States)

    Desai, P.; Brickhouse, N. S.; Drake, J. J.; Edgar, R. J.; Hoogerwerf, R.; Kashyap, V.; Wargelin, B. J.; Smith, R. K.; Huenemoerder, D. P.; Liedahl, D. A.

    2005-06-01

    We discuss here the observations of Fe XVIII and XIX emission lines and compare the X-ray, EUV and FUV lines with the spectral codes widely used today (e.g. FAC and APEC). We assess the relative accuracy of these spectral models and try to identify the critical atomic data and processes. Capella with a narrow enhancement in its emission measure distribution at 6 MK provides a unique opportunity to test the Fe XVIII and Fe XIX model emissivities which peak from 6 to 8 MK. We use the summed spectra from Chandra HETG/ACIS-S and LETG/HRC-S, as well as contemporaneous EUVE and FUSE observations, to measure line ratios for comparison with predictions.

  9. Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey

    Institute of Scientific and Technical Information of China (English)

    Ying-He Zhao; Qiu-Sheng Gu; Zhi-Xin Peng; Lei Shi; Xin-Lian Luo; Qiu-He Peng

    2006-01-01

    As part of a study of star formation history along the Hubble sequence,we present here the results for 11 elliptical galaxies with strong nebular emission lines. After removing the dilution from the underlying old stellar populations by use of stellar population synthesis model, we derive the accurate fluxes of all the emission lines in these objects, which are then classified, using emission line ratios,into one Seyfert 2, six LINERs and four HⅡ galaxies. We also identify one HⅡ galaxy (A1216+04) as a hitherto unknown Wolf-Rayet galaxy from the presence of the WolfRayet broad bump at 4650 A. We propose that the star-forming activities in elliptical galaxies are triggered by either galaxy-galaxy interaction or the merging of a small satellite/a massive star cluster, as has been suggested by recent numerical simulations.

  10. Searching of New Emission-Line Stars using the Astroinformatics Approach

    CERN Document Server

    Škoda, Petr

    2011-01-01

    Using data mining techniques applied on emission line characteristics of Be stars spectra we attempted to find new Be stars candidates in SDSS SEGUE survey. The mid-resolution spectra of confirmed Be stars obtained from VO-compatible archive of Ond\\v{r}ejov observatory 2m telescope were transformed to the spectral resolution of SDSS and important characteristics of emission line profiles were estimated, to be used as a training base of supervised learning methods. The obtained knowledge base of the characteristic shapes and sizes of Be emission lines was finally used to identify new potential candidates in SDSS spectral survey. The several newly found Be stars candidates justify our approach and approve Astroinformatics as a viable research methodology.

  11. Implications of Coronal Line Emission in NGC 4696

    CERN Document Server

    Chatzikos, M; Ferland, G J; Canning, R E A; Fabian, A C; Sanders, J S; van Hoof, P A M; Johnstone, R M; Lykins, M; Porter, R L

    2014-01-01

    We announce a new facility in the spectral code CLOUDY that enables tracking the evolution of a cooling parcel of gas with time. For gas cooling from temperatures relevant to galaxy clusters, earlier calculations estimated the [Fe XIV] {\\lambda}5303 / [Fe X] {\\lambda}6375 luminosity ratio, a critical diagnostic of a cooling plasma, to slightly less than unity. By contrast, our calculations predict a ratio ~3. We revisit recent optical coronal line observations along the X-ray cool arc around NGC 4696 by Canning et al. (2011), which detected [Fe X] {\\lambda}6375, but not [Fe XIV] {\\lambda}5303. We show that these observations are not consistent with predictions of cooling flow models. Differential extinction could in principle account for the observations, but it requires extinction levels (A_V > 3.625) incompatible with previous observations. The non-detection of [Fe XIV] implies a temperature ceiling of 2.1 million K. Assuming cylindrical geometry and transonic turbulent pressure support, we estimate the gas...

  12. A Suzaku Search for Dark Matter Emission Lines in the X-ray Brightest Galaxy Clusters

    CERN Document Server

    Urban, O; Allen, S W; Simionescu, A; Kaastra, J S; Strigari, L E

    2014-01-01

    We present the results of a search for unidentified emission lines in deep Suzaku X-ray spectra for the central regions of the four X-ray brightest galaxy clusters: Perseus, Coma, Virgo and Ophiuchus. We employ an optimized energy range for our analysis (3.2-5.3 keV) that is relatively free of instrumental features, and a baseline plasma emission model that incorporates the abundances of elements with the strongest expected emission lines at these energies (S, Ar, Ca) as free parameters. For the Perseus Cluster core, employing this baseline model, we find evidence for an additional emission feature at an energy $3.51^{+0.02}_{-0.01}$ keV with a flux of ~$2.87\\times10^{-7}$ ph/s/cm^2/arcmin^2. At slightly larger radii, we detect an emission line at 3.59+/-0.02 keV with a flux of ~$4.8\\times10^{-8}$ ph/s/cm^2/arcmin^2. The energies and fluxes of these features are broadly consistent with previous claims, although the radial variation of the line strength appears in tension with standard dark matter (DM) model p...

  13. X-ray Emission Line Profiles from Wind Clump Bow Shocks in Massive Stars

    CERN Document Server

    Ignace, R; Cassinelli, J P

    2012-01-01

    The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two component flow structure of wind and clumps using two "beta" velocity laws. While individual bow shocks tend to generate double horned emission line profiles, a group of bow shocks can lead to line profiles with a range of shapes with blueshifted peak emission that depends on the degree of X-ray photoabsorption by the interclump wind medium, the number of clump structures in the flow, and the radial distribution of the clumps. Using the two beta law prescription, the theoretical emission measure and temperature distribution throughout the...

  14. The Physical Conditions of the X-ray Emission Line Regions in the Circinus Galaxy

    CERN Document Server

    Sako, M; Paerels, F B S; Liedahl, D A; Sako, Masao; Kahn, Steven M.; Paerels, Frits; Liedahl, Duane A.

    2000-01-01

    We present a detailed X-ray spectral analysis of the Circinus Galaxy using archival data obtained with the ASCA satellite. The spectrum shows numerous emission lines in the soft X-ray band from highly ionized ions, as well as Compton reflection and fluorescent lines from neutral or near-neutral matter. We analyze the spectrum in the context of a self-consistent recombination cascade model and find that a nearly flat differential emission measure (DEM) distribution in ionization parameter fits the data. For a fixed solid angle distribution of matter surrounding a point source, this corresponds to a run of electron density of the form, n(r) ~ r^(-3/2), which is suggestive of Bondi accretion onto a central compact mass. Using this density profile and comparing the resulting emission spectra with the ASCA data, the size of the X-ray emission line region is estimated to be < 1 kpc. We also show that the derived density as a function of radius is compatible with the X-ray recombination line emission region being...

  15. Molecular Line Emission Towards High-Mass Clumps: The MALT90 Catalogue

    Science.gov (United States)

    Rathborne, J. M.; Whitaker, J. S.; Jackson, J. M.; Foster, J. B.; Contreras, Y.; Stephens, I. W.; Guzmán, A. E.; Longmore, S. N.; Sanhueza, P.; Schuller, F.; Wyrowski, F.; Urquhart, J. S.

    2016-07-01

    The Millimetre Astronomy Legacy Team 90 GHz survey aims to characterise the physical and chemical evolution of high-mass clumps. Recently completed, it mapped 90 GHz line emission towards 3 246 high-mass clumps identified from the ATLASGAL 870 μm Galactic plane survey. By utilising the broad frequency coverage of the Mopra telescope's spectrometer, maps in 16 different emission lines were simultaneously obtained. Here, we describe the first catalogue of the detected line emission, generated by Gaussian profile fitting to spectra extracted towards each clumps' 870 μm dust continuum peak. Synthetic spectra show that the catalogue has a completeness of > 95%, a probability of a false-positive detection of evolutionary state as estimated from Spitzer mid-IR images, including (1) HNC is relatively brighter in colder, less evolved clumps than those that show active star formation, (2) N2H+ is relatively brighter in the earlier stages, (3) that the observed optical depth decreases as the clumps evolve, and (4) the optically thickest HCO+ emission shows a `blue-red asymmetry' indicating overall collapse that monotonically decreases as the clumps evolve. This catalogue represents the largest compiled database of line emission towards high-mass clumps and is a valuable data set for detailed studies of these objects.

  16. X-ray Line Emission from the Hot Stellar Wind of theta 1 Ori C

    CERN Document Server

    Schulz, N S; Huenemoerder, D P; Lee, J C

    2000-01-01

    We present a first emission line analysis of a high resolution X-ray spectrum of the stellar wind of theta 1 Ori C obtained with the High Energy Transmission grating Spectrometer onboard the Chandra X-ray Observatory. The spectra are resolved into a large number of emission lines from H- and He-like O, Ne, Mg, Si, S, Ar and Fe ions. The He-like Fe XXV and Li-like Fe XXIV appear quite strong indicating very hot emitting regions. From H/He flux ratios, as well as from Fe He/Li emission measure ratios we deduce temperatures ranging from 0.5 to 6.1 x 10^7 K. The He-triplets are very sensitive to density as well. At these temperatures the relative strengths of the intercombination and forbidden lines indicate electron densities well above 10^12 cm^-3. The lines appear significantly broadened from which we deduce a mean velocity of 770 km/s with a spread between 400 and 2000 km/s. Along with results of the deduced emission measure we conclude that the X-ray emission could originate in dense and hot regions with a c...

  17. H2 infrared line emission from the ionized region of planetary nebulae

    CERN Document Server

    Aleman, Isabel

    2010-01-01

    The analysis and interpretation of the H2 line emission from planetary nebulae have been done in the literature assuming that the molecule survives only in regions where the hydrogen is neutral, as in photodissociation, neutral clumps or shocked regions. However, there is strong observational and theoretical evidence that at least part of the H2 emission is produced inside the ionized region of such objects. The aim of the present work is to calculate and analyze the infrared line emission of H2 produced inside the ionized region of planetary nebulae using a one-dimensional photoionization code. The photoionization code Aangaba was improved in order to calculate the statistical population of the H2 energy levels and the intensity of the H2 infrared emission lines in physical conditions typical of planetary nebulae. A grid of models was obtained and the results are analyzed and compared with the observational data. We show that the contribution of the ionized region to the H2 line emission can be important, pa...

  18. Wide-Field Survey of Emission-line Stars in IC 1396

    OpenAIRE

    M. Nakano; Sugitani, K; Watanabe, M.; N. Fukuda; Ishihara, D; Ueno, M.

    2012-01-01

    We have made an extensive survey of emission-line stars in the IC 1396 HII region to investigate the low-mass population of pre-main sequence (PMS) stars. A total of 639 H-alpha emission-line stars were detected in an area of 4.2 deg^2 and their i'-photometry was measured. Their spatial distribution exhibits several aggregates near the elephant trunk globule (Rim A) and bright-rimmed clouds at the edge of the HII region (Rim B and SFO 37, 38, 39, 41), and near HD 206267, which is the main exc...

  19. A General Catalogue of Molecular Hydrogen Emission-Line Objects (MHOs) in Outflows from Young Stars

    CERN Document Server

    Davis, Christopher J; Khanzadyan, Tigran; Smith, Michael D; Jenness, Tim

    2009-01-01

    We present a catalogue of Molecular Hydrogen emission-line Objects (MHOs) in outflows from embedded young stars. All objects are identified in the near-infrared lines of molecular hydrogen, all reside in the Milky Way, and all are associated with jets or molecular outflows from young stars. Objects in both low and high-mass star forming regions are included. This catalogue complements the existing database of Herbig-Haro objects; indeed, for completeness, HH objects that are detected in H2 emission are included in the MHO catalogue.

  20. The Gaia satellite: a tool for Emission Line Stars and Hot Stars

    CERN Document Server

    Martayan, Christophe; Blomme, Ronny; Jonckheere, Anthony; Borges, Marcelo; De Batz, Bertrand; Leroy, Bernard; Sordo, Rosanna; Bouret, Jean-Claude; Martins, Fabrice; Zorec, Jean; Neiner, Coralie; Nazé, Yael; Alecian, Evelyne; Floquet, Michele; Hubert, Anne-Marie; Briot, Danielle; Miroshnichenko, Anatholy; Kolka, Indrek; Stee, Philippe; Lanz, Thierry; Meynet, Georges

    2008-01-01

    The Gaia satellite will be launched at the end of 2011. It will observe at least 1 billion stars, and among them several million emission line stars and hot stars. Gaia will provide parallaxes for each star and spectra for stars till V magnitude equal to 17. After a general description of Gaia, we present the codes and methods, which are currently developed by our team. They will provide automatically the astrophysical parameters and spectral classification for the hot and emission line stars in the Milky Way and other close Local Group galaxies such as the Magellanic Clouds.

  1. Emission Signatures from Sub-parsec Binary Supermassive Black Holes. I. Diagnostic Power of Broad Emission Lines

    Science.gov (United States)

    Nguyen, Khai; Bogdanović, Tamara

    2016-09-01

    Motivated by advances in observational searches for sub-parsec supermassive black hole binaries (SBHBs) made in the past few years, we develop a semi-analytic model to describe spectral emission-line signatures of these systems. The goal of this study is to aid the interpretation of spectroscopic searches for binaries and to help test one of the leading models of binary accretion flows in the literature: SBHB in a circumbinary disk. In this work, we present the methodology and a comparison of the preliminary model with the data. We model SBHB accretion flows as a set of three accretion disks: two mini-disks that are gravitationally bound to the individual black holes and a circumbinary disk. Given a physically motivated parameter space occupied by sub-parsec SBHBs, we calculate a synthetic database of nearly 15 million broad optical emission-line profiles and explore the dependence of the profile shapes on characteristic properties of SBHBs. We find that the modeled profiles show distinct statistical properties as a function of the semimajor axis, mass ratio, eccentricity of the binary, and the degree of alignment of the triple disk system. This suggests that the broad emission-line profiles from SBHB systems can in principle be used to infer the distribution of these parameters and as such merit further investigation. Calculated profiles are more morphologically heterogeneous than the broad emission lines in observed SBHB candidates and we discuss improved treatment of radiative transfer effects, which will allow a direct statistical comparison of the two groups.

  2. The Structure of the Broad Line Region in AGN: I. Reconstructed Velocity-Delay Maps

    CERN Document Server

    Grier, C J; Horne, Keith; Bentz, M C; Pogge, R W; Denney, K D; De Rosa, G; Martini, Paul; Kochanek, C S; Zu, Y; Shappee, B; Siverd, R; Beatty, T G; Sergeev, S G; Kaspi, S; Salvo, C Araya; Bird, J C; Bord, D J; Borman, G A; Che, X; Chen, C; Cohen, S A; Dietrich, M; Doroshenko, V T; Efimov, Yu S; Free, N; Ginsburg, I; Henderson, C B; King, A L; Mogren, K; Molina, M; Mosquera, A M; Nazarov, S V; Okhmat, D N; Pejcha, O; Rafter, S; Shields, J C; Skowron, J; Szczygiel, D M; Valluri, M; van Saders, J L

    2012-01-01

    We present velocity-resolved reverberation results for five active galactic nuclei. We recovered velocity-delay maps using the maximum-entropy method for four objects: Mrk 335, Mrk 1501, 3C120, and PG2130+099. For the fifth, Mrk 6, we were only able to measure mean time delays in different velocity bins of the H\\beta\\ emission line, but see tentative evidence of combined virial motion and infalling gas. The four velocity-delay maps show unique dynamical signatures for each object. For 3C120, the Balmer lines show kinematic signatures consistent with both an inclined disk and infalling gas, but the HeII 4686 emission line is suggestive only of inflow. The Balmer lines in Mrk 335, Mrk 1501, and PG 2130+099 show signs of infalling gas, but the HeII emission in Mrk 335 is consistent with an inclined disk. The maps for 3C120 and Mrk 335 are two of the most clearly defined velocity-delay maps to date. These maps constitute a large increase in the number of objects for which we have resolved velocity-delay maps and ...

  3. Theoretical quasar emission-line profiles. I - Curve-of-growth effects on observed profiles

    Science.gov (United States)

    Hubbard, E. N.; Puetter, R. C.

    1983-01-01

    Radiative transfer effects are examined in an investigation of the kinematics of quasar and Seyfert emission-line regions with pancake cloud geometries. Consideration is given only to the effects of limb brightening with the aspect angle of pancake clouds, assuming that all lines lie on a single portion of the curve of growth. This effect is coupled with several simple but plausible ensemble geometries and dynamics, and a number of theoretical emission-line profiles have been generated. It is shown that these profiles differ substantially depending on both the ensemble geometry and the portion of the curve of growth considered; for a given ensemble geometry, optically thick line profiles are different from optically thick profiles. It is shown that, for radiatively driven clouds, ensembles of clouds which have maximum velocities approaching the terminal velocity of the acceleration mechanism never produce acceptable profiles unless the cloud luminosity is a strongly decreasing function of radius.

  4. Resonant scattering of X-ray emission lines in the hot intergalactic medium

    CERN Document Server

    Churazov, E; Sazonov, S; Sunyaev, R

    2010-01-01

    While very often a hot intergalactic medium (IGM) is optically thin to continuum radiation, the optical depth in resonant lines can be of order unity or larger. Resonant scattering in the brightest X-ray emission lines can cause distortions in the surface brightness distribution, spurious variations in the abundance of heavy elements, changes in line spectral shapes and even polarization of line emission. The magnitude of these effects not only depends on the density, temperature and ionization state of the gas, but is also sensitive to the characteristics of the gas velocity field. This opens a possibility to use resonant scattering as a convenient and powerful tool to study IGM properties. We discuss the application of these effects to galaxy clusters.

  5. First CO(17-16) emission line detected in a z > 6 quasar

    CERN Document Server

    Gallerani, Simona; Neri, Roberto; Maiolino, Roberto

    2014-01-01

    We report the serendipitous detection of the CO(17-16) emission line toward the quasar SDSSJ114816.64+525150.3 (J1148) at redshift z = 6.4 obtained with the Plateau de Bure Interferometer. The CO(17-16) line is possibly contaminated by OH+ emission, that may account for ~ 35 - 60% of the total flux observed. Photo-Dissociation and X-ray Dominated Regions (PDRs and XDRs) models show that PDRs alone cannot reproduce the high luminosity of the CO(17-16) line relative to low-J CO transitions and that XDRs are required. By adopting a composite PDR+XDR model we derive molecular cloud and radiation field properties in the nuclear region of J1148. Our results show that highly excited CO lines represent a sensitive and possibly unique tool to infer the presence of X-ray faint or obscured supermassive black hole progenitors in high-z galaxies.

  6. LZIFU: an emission-line fitting toolkit for integral field spectroscopy data

    CERN Document Server

    Ho, I-Ting; Groves, Brent; Rich, Jeffrey A; Rupke, David S N; Hampton, Elise; Kewley, Lisa J; Bland-Hawthorn, Joss; Croom, Scott M; Richards, Samuel; Schaefer, Adam L; Sharp, Rob; Sweet, Sarah M

    2016-01-01

    We present LZIFU (LaZy-IFU), an IDL toolkit for fitting multiple emission lines simultaneously in integral field spectroscopy (IFS) data. LZIFU is useful for the investigation of the dynamical, physical and chemical properties of gas in galaxies. LZIFU has already been applied to many world-class IFS instruments and large IFS surveys, including the Wide Field Spectrograph, the new Multi Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area (CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail the structure of the toolkit, and how the line fluxes and flux uncertainties are determined, including the possibility of having multiple distinct kinematic components. We quantify the performance of LZIFU, demonstrating its accuracy and robustness. We also show examples of applying LZIFU to CALIFA and SAMI data to construct emission line and kinematic maps, and investigate complex, skewed line prof...

  7. Emission-Line Taxonomy and the Nature of AGN-Looking Galaxies in the SDSS

    Science.gov (United States)

    Cid Fernandes, Roberto; Stasińska, Grażyna; Vale Asari, Natalia; Mateus, Abílio; Schlickmann, Marielli S.; Schoenell, William; Schoenell

    2010-05-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission-line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separetely because one cannot fully classify them onto the standard star-forming, Seyfert, or LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to explain their line ratios and luminosities. Such retired galaxies deserve a place in the emission-line taxonomy.

  8. CIV Emission Line Properties and Systematic Trends in Quasar Black Hole Mass Estimates

    CERN Document Server

    Coatman, Liam; Banerji, Manda; Richards, Gordon T

    2016-01-01

    Black-hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z > 2.1, black hole masses are normally derived using the velocity-width of the CIV broad emission line, based on the assumption that the observed velocity-widths arise from virial-induced motions. In many quasars, the CIV-emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km/s to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the H$\\alpha$ emission line, for 19 luminous ($L_{Bol}$ = 46.5-47.5 erg/s) Sloan Digital Sky Survey quasars, at redshifts 2 2000 km/s, the velocity-widths appear to be dominated by non-virial motions. Black-hole masses, based on the full width at half maximum of the CIV-emission line, can be overestimated by a factor of...

  9. Extraplanar Emission-Line Gas in Edge-On Spiral Galaxies. I. Deep Emission-Line Imaging

    CERN Document Server

    Miller, S T; Miller, Scott T.; Veilleux, Sylvain

    2003-01-01

    The extraplanar diffuse ionized gas (eDIG) in 17 nearby, edge-on disk galaxies is studied using deep Taurus Tunable Filter Halpha and [N II] lambda 6583 images and conventional interference filter Halpha + [N II] lambda 6548, 6583 images which reach flux levels generally below about 1 x 10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}. [N II] lambda 6583/Halpha excitation maps are available for 10 of these objects. All but one galaxy in the sample exhibit eDIG. The contribution of the eDIG to the total Halpha luminosity is relatively constant, of order 12 +/- 4%. The Halpha scale height of the eDIG derived from a two-exponential fit to the vertical emission profile ranges from 0.4 kpc to 17.9 kpc, with an average of 4.3 kpc. This average value is noticeably larger than the eDIG scale height measured in our Galaxy and other galaxies. This difference in scale height is probably due in part to the lower flux limits of our observations. A quantitative analysis of the topology of the eDIG confirms that several galaxies in ...

  10. VizieR Online Data Catalog: Nebular emission lines towards NGC3372 center (Damiani+, 2016)

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maiz Apellaniz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.

    2016-04-01

    Nebular emission lines of H-alpha, [NII] 6584Å, HeI 6678Å, [SII] 6717Å, [SII] 6731Å, towards the center of Carina nebula, are modeled with two gaussians each ('blue' and 'red' components). Best-fit parameters are given in the table. Line widths include the instrumental width of the Giraffe spectrograph (7km/s). Radial velocities are heliocentric. (1 data file).

  11. Time variation of emission lines structure in the spectrum of HR Delfini

    Energy Technology Data Exchange (ETDEWEB)

    Babaev, M.B. (AN Azerbajdzhanskoj SSR, Baku. Shemakhinskaya Astrofizicheskaya Observatoriya)

    1983-04-01

    It is found that H..beta.., HeII lambda4686 and (OIII)lambdalambda4959, 5007 emission lines in the spectrum of nova HR Del had in 1981 four-component structure, as they did earlier. A comparison with 1968-1978 spectra reveals the changes in relative intensities of the internal and external components of these lines. It is concluded that time variations of physical conditions occur in some condensation in the envelope of HR Del.

  12. Searching for gas emission lines in Spitzer Infrared Spectrograph (IRS) spectra of young stars in Taurus

    Science.gov (United States)

    Baldovin-Saavedra, C.; Audard, M.; Güdel, M.; Rebull, L. M.; Padgett, D. L.; Skinner, S. L.; Carmona, A.; Glauser, A. M.; Fajardo-Acosta, S. B.

    2011-04-01

    Context. Our knowledge of circumstellar disks has traditionally been based on studies of dust. However, gas dominates the disk mass and its study is key to our understanding of accretion, outflows, and ultimately planet formation. The Spitzer Space Telescope provides access to gas emission lines in the mid-infrared, providing crucial new diagnostics of the physical conditions in accretion disks and outflows. Aims: We seek to identify gas emission lines in mid-infrared spectra of 64 pre-main-sequence stars in Taurus. Using line luminosities and other known star-disk-outflow parameters, we aim to identify correlations that will help to constrain gas heating, excitation mechanisms, and the line formation. Methods: We have based our study on Spitzer observations using the Infrared Spectrograph (IRS), mainly with the high-resolution modules. Line luminosities (or 3σ upper limits) have been obtained by fitting Gaussian profiles to the lines. We have further searched for correlations between the line luminosities and different parameters related to the star-disk system. Results: We have detected H2 (17.03, 28.22 μm) emission in 6 objects, [Ne II] (12.81 μm) emission in 18 objects, and [Fe II] (17.93, 25.99 μm) emission in 7 objects. [Ne II] detections are found primarily in Class II objects. The luminosity of the [Ne II] line (LNeII) is in general higher for objects known to drive jets than for those without known jets, but the two groups are not statistically distinguishable. LNeII is correlated with X-ray luminosity, but for Class II objects only. LNeII is also correlated with disk mass and accretion rate when the sample is divided into high and low accretors. Furthermore, we find correlations of LNeII with mid-IR continuum luminosity and with luminosity of the [O I] (6300 Å) line, the latter being an outflow tracer. L [FeII] correlates with Ṁacc. No correlations were found between LH2 and several tested parameters. Conclusions: Our study reveals a general trend

  13. Radio continuum detection in blue early-type weak emission line galaxies

    OpenAIRE

    Paswan, A.; Omar, A.

    2016-01-01

    The star formation rates (SFRs) in weak emission line (WEL) galaxies in a volume-limited ($0.02 < z < 0.05$) sample of blue early-type galaxies (ETGs) identified from SDSS, are constrained here using 1.4 GHz radio continuum emission. The direct detection of 1.4 GHz radio continuum emission is made in 8 WEL galaxies and a median stacking is performed on 57 WEL galaxies using VLA FIRST images. The median stacked 1.4 GHz flux density and luminosity are estimated as 79 $\\pm$ 19 $\\mu$Jy and 0.20 $...

  14. Method for measuring radial impurity emission profiles using correlations of line integrated signals

    Science.gov (United States)

    Kuldkepp, M.; Brunsell, P. R.; Drake, J.; Menmuir, S.; Rachlew, E.

    2006-04-01

    A method of determining radial impurity emission profiles is outlined. The method uses correlations between line integrated signals and is based on the assumption of cylindrically symmetric fluctuations. Measurements at the reversed field pinch EXTRAP T2R show that emission from impurities expected to be close to the edge is clearly different in raw as well as analyzed data to impurities expected to be more central. Best fitting of experimental data to simulated correlation coefficients yields emission profiles that are remarkably close to emission profiles determined using more conventional techniques. The radial extension of the fluctuations is small enough for the method to be used and bandpass filtered signals indicate that fluctuations below 10kHz are cylindrically symmetric. The novel method is not sensitive to vessel window attenuation or wall reflections and can therefore complement the standard methods in the impurity emission reconstruction procedure.

  15. IFU spectroscopy of 10 early type galactic nuclei: II - Nuclear emission line properties

    CERN Document Server

    Ricci, T V; Menezes, R B

    2014-01-01

    Although it is well known that massive galaxies have central black holes, most of them accreting at low Eddington ratios, many important questions still remain open. Among them, are the nature of the ionizing source, the characteristics and frequencies of the broad line region and of the dusty torus. We report observations of 10 early-type galactic nuclei, observed with the IFU/GMOS spectrograph on the Gemini South telescope, analysed with standard techniques for spectral treatment and compared with results obtained with principal component analysis Tomography (Paper I). We performed spectral synthesis of each spaxel of the data cubes and subtracted the stellar component from the original cube, leaving a data cube with emission lines only. The emission lines were decomposed in multi-Gaussian components. We show here that, for eight galaxies previously known to have emission lines, the narrow line region can be decomposed in two components with distinct line widths. In addition to this, broad H$\\alpha$ emissio...

  16. C IV emission-line properties and systematic trends in quasar black hole mass estimates

    Science.gov (United States)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.

    2016-09-01

    Black hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z ≳ 2.1, black hole masses are normally derived using the velocity width of the C IV λ λ1548, 1550 broad emission line, based on the assumption that the observed velocity widths arise from virial-induced motions. In many quasars, the C IV emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km s-1 to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the Hα λ6565 emission line, for 19 luminous (LBol = 46.5-47.5 erg s-1) Sloan Digital Sky Survey quasars, at redshifts 2 2000 km s-1, the velocity widths appear to be dominated by non-virial motions. Black hole masses, based on the full width at half-maximum of the C IV emission line, can be overestimated by a factor of 5 at large blueshifts. A larger sample of quasar spectra with both C IV and H β, or Hα, emission lines will allow quantitative corrections to C IV-based black hole masses as a function of blueshift to be derived. We find that quasars with large C IV blueshifts possess high Eddington luminosity ratios and that the fraction of high-blueshift quasars in a flux-limited sample is enhanced by a factor of approximately 4 relative to a sample limited by black hole mass.

  17. The Impact of Diffuse Ionized Gas on Emission-line Ratios and Gas Metallicity Measurements

    Science.gov (United States)

    Zhang, Kai; Yan, Renbin; MaNGA Team

    2016-01-01

    Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impact the measurements of emission line ratios, hence the gas-phase metallicity measurements and the interpretation of diagnostic diagrams. We demonstrate that emission line surface brightness (SB) is a reasonably good proxy to separate HII regions from regions dominated by diffuse ionized gas. For spatially-adjacent regions or regions at the same radius, many line ratios change systematically with emission line surface brightness, reflecting a gradual increase of dominance by DIG towards low SB. DIG could significantly bias the measurement of gas metallicity and metallicity gradient. Because DIG tend to have a higher temperature than HII regions, at fixed metallicity DIG displays lower [NII]/[OII] ratios. DIG also show lower [OIII]/[OII] ratios than HII regions, due to extended partially-ionized regions that enhance all low-ionization lines ([NII], [SII], [OII], [OI]). The contamination by DIG is responsible for a substantial portion of the scatter in metallicity measurements. At different surface brightness, line ratios and line ratio gradients can differ systematically. As DIG fraction could change with radius, it can affect the metallicity gradient measurements in systematic ways. The three commonly used strong-line metallicity indicators, R23, [NII]/[OII], O3N2, are all affected in different ways. To make robust metallicity gradient measurements, one has to properly isolate HII regions and correct for DIG contamination. In line ratio diagnostic diagrams, contamination by DIG moves HII regions towards composite or LINER-like regions.

  18. THE SURVEY OF LINES IN M31 (SLIM): INVESTIGATING THE ORIGINS OF [C II] EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Kapala, M. J.; Sandstrom, K.; Groves, B.; Kreckel, K.; Schinnerer, E.; Walter, F.; Fouesneau, M. [Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Croxall, K. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Dalcanton, J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Leroy, A., E-mail: kapala@mpia.de [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

    2015-01-01

    The [C II] 158 μm line is one of the strongest emission lines observed in star-forming galaxies and has been empirically measured to correlate with the star-formation rate (SFR) globally and on kiloparsec scales. However, because of the multiphase origins of [C II], one might expect this relation to break down at small scales. We investigate the origins of [C II] emission by examining high spatial resolution observations of [C II] in M31 with the Survey of Lines in M31. We present five ∼700 × 700 pc (3' × 3') fields mapping the [C II] emission, Hα emission, and the ancillary infrared (IR) data. We spatially separate star-forming regions from diffuse gas and dust emission on ∼50 pc scales. We find that the [C II]-SFR correlation holds even at these scales, although the relation typically has a flatter slope than found at larger (kiloparsec) scales. While the Hα emission in M31 is concentrated in the SFR regions, we find that a significant amount (∼20%-90%) of the [C II] emission comes from outside star-forming regions and that the total IR emission (TIR) has the highest diffuse fraction of all SFR tracers. We find a weak correlation of the [C II]/TIR to dust color in each field and find a large-scale trend of increasing [C II]/TIR with galactocentric radius. The differences in the relative diffuse fractions of [C II], Hα, and IR tracers are likely caused by a combination of energetic photon leakage from H II regions and heating by the diffuse radiation field arising from older (B-star) stellar populations. However, we find that by averaging our measurements over kiloparsec scales, these effects are minimized, and the relation between [C II] and SFR found in other nearby galaxy studies is retrieved.

  19. The Nature of Active Galactic Nuclei with Velocity Offset Emission Lines

    Science.gov (United States)

    Müller-Sánchez, F.; Comerford, J.; Stern, D.; Harrison, F. A.

    2016-10-01

    We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field spectroscopy to probe the morphology and kinematics of the ionized gas in four velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey. These objects possess optical emission lines that are offset in velocity from systemic as measured from stellar absorption features. At a resolution of ∼0.″18, OSIRIS allows us to distinguish which velocity offset emission lines are produced by the motion of an AGN in a dual supermassive black hole system, and which are produced by outflows or other kinematic structures. In three galaxies, J1018+2941, J1055+1520, and J1346+5228, the spectral offset of the emission lines is caused by AGN-driven outflows. In the remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that contains the peak of Paα emission 0.″2 from the center of the galaxy. The most plausible explanation for the origin of this spatially and kinematically offset peak is that it is a region of enhanced Paα emission located at the intersection zone between the nuclear disk and the bar of the galaxy. In all four objects, the peak of ionized gas emission is not spatially coincident with the center of the galaxy as traced by the peak of the near-IR continuum emission. The peaks of ionized gas emission are spatially offset from the galaxy centers by 0.″1–0.″4 (0.1–0.7 kpc). We find that the velocity offset originates at the location of this peak of emission, and the value of the offset can be directly measured in the velocity maps. The emission-line ratios of these four velocity-offset AGNs can be reproduced only with a mixture of shocks and AGN photoionization. Shocks provide a natural explanation for the origin of the spatially and spectrally offset peaks of ionized gas emission in these galaxies. Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the

  20. Locally Optimally Emitting Clouds and the Variable Broad Emission Line Spectrum of NGC 5548

    Science.gov (United States)

    Korista, Kirk T.; Goad, Michael R.

    2000-06-01

    In recent work Baldwin et al. proposed that in the geometrically extended broad-line regions (BLRs) of quasars and active galactic nuclei, a range in line-emitting gas properties (e.g., density, column density) might exist at each radius and showed that under these conditions the broad emission line spectra of these objects may be dominated by selection effects introduced by the atomic physics and general radiative transfer within the large pool of line-emitting entities. In this picture, the light we see originates in a vast amalgam of emitters but is dominated by those emitters best able to reprocess the incident continuum into a particular emission line. We test this ``locally optimally emitting clouds'' (LOC) model against the extensive spectroscopic database of the Seyfert 1 galaxy NGC 5548. The time-averaged, integrated-light UV broad emission line spectrum from the 1993 Hubble Space Telescope (HST) monitoring campaign is reproduced via the optimization of three global geometric parameters: the outer radius, the index controlling the radial cloud covering fraction of the continuum source, and the integrated cloud covering fraction. We make an ad hoc selection from the range of successful models, and for a simple spherical BLR geometry we simulate the emission-line light curves for the 1989 IUE and 1993 HST campaigns, using the respective observed UV continuum light curves as drivers. We find good agreement between the predicted and observed light curves and lags-a demonstration of the LOC picture's viability as a means to understanding the BLR environment. Finally, we discuss the next step in developing the LOC picture, which involves the marriage of echo-mapping techniques with spectral simulation grids such as those presented here, using the constraints provided by a high-quality, temporally well-sampled spectroscopic data set.

  1. Bayesian Redshift Classification of Emission-line Galaxies with Photometric Equivalent Widths

    CERN Document Server

    Leung, Andrew S; Gawiser, Eric; Ciardullo, Robin; Komatsu, Eiichiro; Zeimann, Gregory R; Bridge, Joanna S; Feldmeier, John J; Finkelstein, Steven L; Gebhardt, Karl; Gronwall, Caryl; Hagen, Alex; Hill, Gary J; Schneider, Donald P

    2015-01-01

    We present a Bayesian approach to the redshift classification of emission-line galaxies when only a single emission line is detected spectroscopically. We consider the case of surveys for high-redshift ${\\rm Ly{\\alpha}}$-emitting galaxies (LAEs), which have traditionally been classified via an inferred rest-frame equivalent width $(W_{\\rm Ly\\alpha})$ greater than $20 {\\rm \\,\\AA}$. Our Bayesian method relies on known prior probabilities in measured emission-line luminosity functions and equivalent width distributions for the galaxy populations in question, and it returns the probability that an object is an LAE given the characteristics observed. This approach will be directly relevant for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), which seeks to classify $\\sim$$10^6$ emission-line galaxies into LAEs and low-redshift [O II] emitters. For a simulated HETDEX catalog with realistic measurement noise, our Bayesian method recovers $86\\%$ of LAEs missed by the traditional $W_{\\rm Ly\\alpha} > 20 {\\rm...

  2. Cross section calculations of astrophysical interest. [for theories of absorption and emission lines

    Science.gov (United States)

    Gerjuoy, E.

    1974-01-01

    Cross sections are discussed for rotational excitation associated with theories of absorption and emission lines from molecules in space with emphasis on H2CO, CO, and OH by collisions with neutral particles such H, H2, and He. The sensitivity of the Thaddeus equation for the H2CO calculation is examined.

  3. Effects of the Electron Energy Distribution Function on Line and Continuum Emission

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, S B; Shlyaptseva, A S

    2004-03-18

    Effects of suprathermal (''hot'') electrons on the predictions of K- and L-shell non-LTE collisional-radiative atomic kinetics models are presented through an investigation of various electron distribution functions (EDFs) on collisional rates and spectra. It is shown that while most collisional rates are fairly insensitive to the functional form and characteristic energy of the hot electrons as long as their characteristic energy is larger than the threshold energy for the collisional process, collisional excitation and ionization rates are highly sensitive to the fraction of hot electrons. This permits the development of robust spectroscopic diagnostics that can be used to detect the presence of hot electrons from x-ray line emission spectra. Hot electrons are shown to increase and spread out plasma charge state distributions, amplify the intensities of emission lines fed by direct collisional excitation and radiative cascades, and alter the structure of satellite and EUV line emission features. The characteristic energy, functional form, and spatial properties of hot electron distributions in plasmas are open to characterization through their effects on high-energy continuum emission and on the polarization of spectral lines.

  4. Predicted emission lines from giant HII regions ionized by aging star clusters

    OpenAIRE

    García Vargas, M. L.; Bressan, A.; Angeles I. Díaz

    1995-01-01

    This is an electronic version of an article published in Astronomy and Astrophysics, Supplement Series. García-Vargas, M.L., Bressan, A. and A.I. Díaz. Predicted emission lines from giant HII regions ionized by aging star clusters. Astronomy and Astrophysics 112, Supplement Series (1995): 35-70

  5. Laboratory Measurements of Fe xxiv Line Emission: 3→2 Transitions near Excitation Threshold

    International Nuclear Information System (INIS)

    Using the Electron Beam Ion Trap facility at Lawrence Livermore National Laboratory, we have measured relative cross sections for Fe xxiv line emission at electron energies between 0.7 and 3.0 keV. The measurements include line formation by direct electron impact excitation (DE), radiative cascades, resonant excitation (RE), and dielectronic recombination (DR) satellites with captured electrons in n≥5 levels. Good agreement with R-matrix and distorted wave calculations is found. In collisionally ionized plasmas, at temperatures near where the ion abundance peaks (kTe ∼1.7 keV), the RE contributions are found to be approx-lt 5% of the line emission, while the DR satellites contribute approx-lt 10%. While good agreement with state-of-the-art atomic physics calculations is found, there is less good agreement with existing spectral synthesis codes in common astrophysical use. For the Fe xxiv 3p3/2 →2s1/2, 3p1/2 →2s1/2, and 3d5/2 →2p3/2 transitions, the synthesis code MEKAL underestimates the emissivity in coronal equilibrium by ∼20% at temperatures near where the ion abundance peaks. In situations where the ionization balance is not solely determined by the electron temperature, RE and DR satellites may contribute a considerable fraction of the line emission. copyright copyright 1999. The American Astronomical Society

  6. The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines

    CERN Document Server

    Sun, Mouyuan; Shen, Yue; Brandt, W N; Dawson, Kyle; Denney, Kelly D; Hall, Patrick B; Ho, Luis C; Horne, Keith; Jiang, Linhua; Richards, Gordon T; Schneider, Donald P; Bizyaev, Dmitry; Kinemuchi, Karen; Oravetz, Daniel; Pan, Kaike; Simmons, Audrey

    2015-01-01

    We explore the variability of quasars in the MgII and Hbeta broad emission lines and UV/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over $6$ months, containing 357 quasars with MgII and 41 quasars with Hbeta . On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional $2854$ quasars with MgII and 572 quasars with Hbeta. The MgII emission line is significantly variable ($\\Delta f/f$ 10% on 100-day timescales), indicating that it is feasible to use the broad MgII line for reverberation mapping studies. The data also confirm that continuum variability increases with timescale and decreases with luminosity, and the continuum light curves are consistent with a damped random-walk model on rest-frame timescales of $\\gtrsim 5$ days. We compare the emission-line and...

  7. Flux calibrated emission line imaging of extended sources using GTC/OSIRIS Tunable Filters

    CERN Document Server

    Mayya, Y D; Vega, O; Mendez-Abreu, J; Terlevich, R; Terlevich, E; Bertone, E; Rodriguez-Merino, L H; Munoz-Tunon, C; Rodriguez-Espinosa, J M; Almeida, J Sanchez; Aguerri, J A L

    2012-01-01

    We investigate the utility of the Tunable Filters (TFs) for obtaining flux calibrated emission line maps of extended objects such as galactic nebulae and nearby galaxies, using the OSIRIS instrument at the 10.4-m GTC. Despite a relatively large field of view of OSIRIS (8'x8'), the change in the wavelength across the field (~80 Ang) and the long-tail of Tunable Filter (TF) spectral response function, are hindrances for obtaining accurate flux calibrated emission-line maps of extended sources. The purpose of this article is to demonstrate that emission-line maps useful for diagnostics of nebula can be generated over the entire field of view of OSIRIS, if we make use of theoretically well-understood characteristics of TFs. We have successfully generated the flux-calibrated images of the nearby, large late-type spiral galaxy M101 in the emission lines of Halpha, [NII]6583, [SII]6716 and [SII]6731. We find that the present uncertainty in setting the central wavelength of TFs (~1 Ang), is the biggest source of erro...

  8. Determination of sulfur in biodiesel microemulsions using the summation of the intensities of multiple emission lines.

    Science.gov (United States)

    Young, Carl G; Amais, Renata S; Schiavo, Daniela; Garcia, Edivaldo E; Nóbrega, Joaquim A; Jones, Bradley T

    2011-05-15

    A method for the determination of sulfur in biodiesel samples by inductively coupled plasma optical emission spectrometry which uses microemulsion for sample preparation and the summation of the intensities of multiple emission lines has been developed. Microemulsions were prepared using 0.5 mL of 20% v/v HNO(3), 0.5 mL of Triton X-100, 2-3 mL of biodiesel sample, and diluted with n-propanol to a final volume of 10 mL. Summation of the emission intensities of multiple sulfur lines allowed for increased accuracy and sensitivity. The amounts of sulfur determined experimentally were between 2 and 7 mg L(-1), well below legislative standards for many countries. Recoveries obtained ranged from 72 to 119%, and recoveries obtained for the 182.562 nm line were slightly lower. This is most likely due to its lower sensitivity. Using microemulsion for sample preparation and the summation of the intensities of multiple emission lines for the successful determination of sulfur in biodiesel has been demonstrated. PMID:21482315

  9. Deficit of far-infrared [CII] line emission toward the Galactic center

    CERN Document Server

    Nakagawa, T; Yui, Y Y; Okuda, H; Mochizuki, K; Shibai, H; Nishimura, T; Low, F J; Nakagawa, Takao; Doi, Yasuo; Yui, Yukari Yamashita; Okuda, Haruyuki; Mochizuki, Kenji; Shibai, Hiroshi; Nishimura, Tetsuo; Low, Frank J

    1995-01-01

    We have observed the [CII] 158 micron line emission from the Galactic plane (-10 deg < l < 25 deg, |b| <= 3 deg) with the Balloon-borne Infrared Carbon Explorer (BICE). The observed longitudinal distribution of the [CII] line emission is clearly different from that of the far-infrared continuum emission; the Galactic center is not the dominant peak in the [CII] emission. Indeed, the ratio of the [CII] line emission to far-infrared continuum (I_[CII] / I_FIR) is systematically low within the central several hundred parsecs of the Galaxy. The observational results indicate that the abundance of the C+ ions themselves is low in the Galactic center. We attribute this low abundance mainly to soft UV radiation with fewer C-ionizing photons. This soft radiation field, together with the pervasively high molecular gas density, makes the molecular self-shielding more effective in the Galactic center. The self-shielding further reduces the abundance of C+ ions, and raises the temperature of molecular gas at the...

  10. RESIK observations of He-like Ar X-ray line emission in solar flares

    CERN Document Server

    Sylwester, J; Phillips, K J H

    2008-01-01

    The Ar XVII X-ray line group principally due to transitions 1s2 - 1s2l (l=s, p) near 4 Anstroms was observed in numerous flares by the RESIK bent crystal spectrometer aboard CORONAS-F between 2001 and 2003. The three line features include the Ar XVII w (resonance line), a blend of x and y (intercombination lines), and z (forbidden line), all of which are blended with Ar XVI dielectronic satellites. The ratio G, equal to [I(x+y) + I(z)]/I(w), varies with electron temperature Te mostly because of unresolved dielectronic satellites. With temperatures estimated from GOES X-ray emission, the observed G ratios agree fairly well with those calculated from CHIANTI and other data. With a two-component emission measure, better agreement is achieved. Some S XV and S XVI lines blend with the Ar lines, the effect of which occurs at temperatures greater than 8MK, allowing the S/Ar abundance ratio to be determined. This is found to agree with coronal values. A nonthermal contribution is indicated for some spectra in the rep...

  11. Hints of Correlations Between Broad-Line and Radio Variations for AGNs

    CERN Document Server

    Liu, H T; Feng, H C; Li, S K

    2014-01-01

    In this paper, we study the issue of correlation between broad-line and radio variations under a spherical broad-line region (BLR), and attempt to locate the position of radio (and gamma-ray) emitting region in jet of radio-loud active galactic nuclei (AGNs). Considering the radial profiles of the radius and number density of clouds in the spherical BLR, we have deduced new formulae connecting the radio emitting position $R_{\\rm{jet}}$ to the time lags $\\tau_{\\rm{ob}}$ between broad-line and radio variations, and the BLR inner and outer radii. The new formulae are applied to broad-line radio-loud Fermi-LAT AGNs, 3C 273 and 3C 120. For 3C 273, a common feature of negative time lags is found in the cross-correlation functions between light curves of radio emission and the Balmer lines, and as well Ly$\\alpha$ $\\lambda 1216$ and C IV $\\lambda 1549$ lines. $R_{\\rm{jet}}=$ 1.0--2.6 parsec (pc) are obtained from the time lags of the Balmer lines. For 3C 120, positive lags of about 0.3 yr are found between the 15 GHz...

  12. Detection of emission lines from z ˜ 3 DLAs towards the QSO J2358+0149

    Science.gov (United States)

    Srianand, Raghunathan; Hussain, Tanvir; Noterdaeme, Pasquier; Petitjean, Patrick; Krühler, Thomas; Japelj, Jure; Pâris, Isabelle; Kashikawa, Nobunari

    2016-07-01

    Using VLT/X-shooter, we searched for emission line galaxies associated with four damped Lyman α systems (DLAs) and one sub-DLA at 2.73 ≤z ≤3.25 towards QSO J2358+0149. We detect [O III] emission from a `low-cool' DLA at zabs = 2.9791 (having log N(H I) = 21.69 ± 0.10, [Zn/H] = -1.83 ± 0.18) at an impact parameter of, ρ ˜ 12 kpc. The associated galaxy is compact with a dynamical mass of (1-6) × 109 M⊙, very high excitation ([O III]/[O II] and [O III]/[Hβ] both greater than 10), 12+[O/H]≤8.5 and moderate star formation rate (SFR ≤2 M⊙ yr-1). Such properties are typically seen in the low-z extreme blue compact dwarf galaxies. The kinematics of the gas is inconsistent with that of an extended disc and the gas is part of either a large scale wind or cold accretion. We detect Lyα emission from the zabs = 3.2477 DLA [having log N(H I) = 21.12 ± 0.10 and [Zn/H] = -0.97 ± 0.13]. The Lyα emission is redshifted with respect to the metal absorption lines by 320 km s-1, consistent with the location of the red hump expected in radiative transport models. We derive SFR ˜0.2-1.7 M⊙ yr-1 and Lyα escape fraction of ≥10 per cent. No other emission line is detected from this system. Because the DLA has a small velocity separation from the quasar (˜500 km s-1) and the DLA emission is located within a small projected distance (ρ < 5 kpc), we also explore the possibility that the Lyα emission is being induced by the QSO itself. QSO-induced Lyα fluorescence is possible if the DLA is within a physical separation of 340 kpc to the QSO. Detection of stellar continuum light and/or the oxygen emission lines would disfavour this possibility. We do not detect any emission line from the remaining three systems.

  13. Detection of an oxygen emission line from a high redshift galaxy in the reionization epoch

    CERN Document Server

    Inoue, Akio K; Matsuo, Hiroshi; Mawatari, Ken; Shimizu, Ikkoh; Shibuya, Takatoshi; Ota, Kazuaki; Yoshida, Naoki; Zackrisson, Erik; Kashikawa, Nobunari; Kohno, Kotaro; Umehata, Hideki; Hatsukade, Bunyo; Iye, Masanori; Matsuda, Yuichi; Okamoto, Takashi; Yamaguchi, Yuki

    2016-01-01

    The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The non-detection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium.

  14. Detection of an oxygen emission line from a high-redshift galaxy in the reionization epoch.

    Science.gov (United States)

    Inoue, Akio K; Tamura, Yoichi; Matsuo, Hiroshi; Mawatari, Ken; Shimizu, Ikkoh; Shibuya, Takatoshi; Ota, Kazuaki; Yoshida, Naoki; Zackrisson, Erik; Kashikawa, Nobunari; Kohno, Kotaro; Umehata, Hideki; Hatsukade, Bunyo; Iye, Masanori; Matsuda, Yuichi; Okamoto, Takashi; Yamaguchi, Yuki

    2016-06-24

    The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The nondetection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium. PMID:27312046

  15. Detection of an oxygen emission line from a high-redshift galaxy in the reionization epoch

    Science.gov (United States)

    Inoue, Akio K.; Tamura, Yoichi; Matsuo, Hiroshi; Mawatari, Ken; Shimizu, Ikkoh; Shibuya, Takatoshi; Ota, Kazuaki; Yoshida, Naoki; Zackrisson, Erik; Kashikawa, Nobunari; Kohno, Kotaro; Umehata, Hideki; Hatsukade, Bunyo; Iye, Masanori; Matsuda, Yuichi; Okamoto, Takashi; Yamaguchi, Yuki

    2016-06-01

    The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The nondetection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium.

  16. The SDSS-IV eBOSS emission-line galaxy pilot survey

    CERN Document Server

    Comparat, J; Jouvel, S; Raichoor, A; Kneib, J-P; Yeche, C; Abdalla, F B; Cras, C Le; Maraston, C; Wilkinson, D M; Zhu, G; Jullo, E; Prada, F; Schlegel, D; Xu, Z; Zou, H; Bautista, J; Bizyaev, D; Bolton, A; Brownstein, J R; Dawson, K S; Gaulme, S Escoffier P; Kinemuchi, K; Malanushenko, E; Malanushenko, V; Mariappan, V; Newman, J A; Oravetz, D; Pan, K; Percival, W J; Prakash, A; Schneider, D P; Simmons, A; Allam, T M C Abbott S; Banerji, M; Benoit-Lévy, A; Bertin, E; Brooks, D; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Castander, F J; Cunha, C E; da Costa, L N; Desai, S; Doel, P; Eifler, T F; Estrada, J; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Lima, M; Maia, M A G; March, M; Marshall, J L; Miquel, R; Plazas, A A; Reil, K; Roe, N; Romer, A K; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Thomas, D; Walker, A R; Zhang, Y

    2015-01-01

    The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe approximately 270,000 emission-line galaxies (ELGs) to measure the Baryonic Acoustic Oscillation standard ruler (BAO) at redshift 0.9. To test different ELG selection algorithms, based on data from several imaging surveys, 9,000 spectra were observed with the SDSS spectrograph as a pilot survey. First, we provide a detailed description of each target selection algorithm tested. Then, using visual inspection and redshift quality flags, we find that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a robust BAO measurement. Also, we show the correlations between sky emission, signal-to-noise ratio in the emission lines and redshift error. As a result, we provide robust redshift distributions for the different target selection schemes tested. Finally, we infer two optimal target selection algorithms to be applied on DECam photometry that fulfill the eBOSS ...

  17. Shift and broadening of emission lines in Nd$^{3+}$:YAG laser crystal influenced by input energy

    Indian Academy of Sciences (India)

    POURMAND SEYED EBRAHIM; REZAEI GHASEM

    2016-06-01

    Spectroscopic properties of the flashlamp-pumped Nd$^{3+}$:YAG laser as a function of input energy were studied over the range of 18–75 J. The spectral widths and shifts of quasi-three-level and four-level inter-Stark emissions within the respective intermanifold transitions of $^4$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2} $ and $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ were investigated. The emission lines of $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2}$ shifted towards longer wavelength (red shift) and broadened, while the positions and linewidths of the $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ transition lines remained constant by increasing the pumping energy. This is attributed to the thermal population as well as one-phonon and multiphonon emission processes in the ground state. This phenomenon degrades the output performance of the lasers.

  18. Resonance scattering in the X-ray emission line profiles of Zeta Puppis

    CERN Document Server

    Leutenegger, M A; Kahn, S M; Owocki, S P; Paerels, F B S

    2007-01-01

    We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star Zeta Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.

  19. Emission Lines of Boron, Carbon, Oxygen and Iron in Tokamak Plasma

    Institute of Scientific and Technical Information of China (English)

    DI Long; WAN Bao-Nian; ZHAO Gang; ZHANG Jie; SHI Jian-Rong; WANG Shou-Jun; DONG Quan-Li; ZHAO Jing; LI Yu-Tong; FU Jia; WANG Fu-Di; SHI Yue-Jiang

    2011-01-01

    The emission lines of B,C,O and Fe in tokamak plasma are reported. The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate atomic data.General agreement is obtained between the results of experiment and computation.Most of the lines in the spectra are identified,and the relative number density ratios orB,C,O and Fe are determined.It is found that the processes of line formation in our experiment are similar to those in the stellar coronae.The line-averaged electron density of the tokamak plasma is measured by the HCN laser,indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI.

  20. Silicon X-ray line emission from solar flares and active regions

    International Nuclear Information System (INIS)

    New observations of solar flare and active region X-ray spectra obtained with the Columbia University instrument on OSO-8 are presented and discussed. The high sensitivity of the graphite crystal panel has allowed both line and continuum spectra to be observed with moderate spectral resolution. Observations with higher spectral resolution have been made with a panel of pentaerythritol crystals. Twenty-nine lines between 1.5 and 7.0 A have been resolved and identified, including several dielectronic recombination satellite lines to Si XIV and Si XIII lines which have been observed for the first time. It has been found that thermal continuum models specified by single values of temperature and emission measure have fitted that data adequately, there being good agreement with the values of these parameters derived from line intensity ratios. (Auth.)

  1. The near-IR shape of the big blue bump emission from quasars: under the hot dust emission

    CERN Document Server

    Kishimoto, M; Blaes, Omer M; Kishimoto, Makoto; Antonucci, Robert; Blaes, Omer

    2006-01-01

    One primary difficulty in understanding the nature of the putative accretion disk in the central engine of AGNs is that some of its key intrinsic spectral signatures are buried under the emissions from the surrounding regions, i.e. the broad line region (BLR) and the obscuring torus. We argue here that these signatures can be revealed by using optical and near-IR polarization. At least in some quasars, the polarization is seen only in the continuum and is not shared by emission lines. In this case, the polarized flux is considered to show the intrinsic spectrum interior to the BLR, removing off the emissions from the BLR and torus. We have used this polarization to reveal the Balmer-edge feature and near-IR spectral shape of the central engine, both of which are important for testing the fundamental aspects of the models.

  2. On the thermal line emission from the outflows in ultraluminous X-ray sources

    CERN Document Server

    Xu, Ya-Di

    2016-01-01

    The atomic features in the X-ray spectra of the ultraluminous X-ray source (ULX) may be associated with the outflow (Middleton et al. 2015), which may provide a way to explore the physics of the ULXs. We construct a conical outflow model, and calculate the thermal X-ray Fe emission lines from the outflows. Our results show that thermal line luminosity decreases with increasing outflow velocity or/and opening angle of the outflow for a fixed kinetic power of the outflows. Assuming the kinetic power of the outflows to be comparable with the accretion power in the ULXs, we find that the equivalent width can be several eV for the thermal X-ray Fe emission line from the outflows in the ULXs with stellar mass black holes. The thermal line luminosity is proportional to 1/M (M is the black hole mass of the ULX). The equivalent width decreases with the black hole mass, which implies that the Fe line emission from the outflows can hardly be detected if the ULXs contain intermediate mass black holes. Our results suggest...

  3. A z ∼ 5.7 Lyα emission line with an ultrabroad red wing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Huan; Wang, JunXian [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, Zhen-Ya; Malhotra, Sangeeta; Rhoads, James E. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Infante, Leopoldo, E-mail: yanghuan@mail.ustc.edu.cn, E-mail: jxw@mail.ustc.edu.cn, E-mail: zzheng13@asu.edu, E-mail: smalhotr@asu.edu, E-mail: james.rhoads@asu.edu, E-mail: linfante@astro.puc.cl [Institute of Astrophysics, Ponticia Universidad Catolica, Santiago (Chile)

    2014-03-20

    Using the Lyα emission line as a tracer of high-redshift, star-forming galaxies, hundreds of Lyα emission line galaxies (LAEs) at z > 5 have been detected. These LAEs are considered to be low-mass young galaxies, critical to the re-ionization of the universe and the metal enrichment of the circumgalactic medium (CGM) and the intergalactic medium (IGM). It is assumed that outflows in LAEs can help both ionizing photons and Lyα photons escape from galaxies. However, we still know little about the outflows in high-redshift LAEs due to observational difficulties, especially at redshift >5. Models of Lyα radiative transfer predict asymmetric Lyα line profiles with broad red wings in LAEs with outflows. Here, we report a z ∼ 5.7 Lyα emission line with a broad red wing extending to >1000 km s{sup –1} relative to the peak of Lyα line, which has been detected in only a couple of z > 5 LAEs until now. If the broad red wing is ascribed to gas outflow instead of active galactic nucleus activity, the outflow velocity could be larger than the escape velocity (∼500 km s{sup –1}) of a typical halo mass of z ∼ 5.7 LAEs, which is consistent with the idea that outflows in LAEs disperse metals to CGM and IGM.

  4. A z ~ 5.7 Ly{\\alpha} Emission Line with an Ultra Broad Red Wing

    CERN Document Server

    Yang, Huan; Zheng, Zhen-Ya; Malhotra, Sangeeta; Rhoads, James E; Infante, Leopoldo

    2014-01-01

    Using Ly{\\alpha} emission line as a tracer of high redshift star forming galaxies, hundreds of Ly{\\alpha} emission line galaxies (LAEs) at z > 5 have been detected. These LAEs are considered to be low mass young galaxies, critical to the reionization of the universe and the metal enrichment of circumgalactic medium (CGM) and intergalactic medium (IGM). It is assumed that outflows in LAEs can help ionizing photons and Ly{\\alpha} photons escape out of galaxies. However we still know little about the outflows in high redshifts LAEs due to observational difficulties, especially at redshift > 5. Models of Ly{\\alpha} radiative transfer predict asymmetric Ly{\\alpha} line profiles with broad red wing in LAEs with outflows. Here we report a z ~ 5.7 Ly{\\alpha} emission line with a broad red wing extending to > 1000 km/s relative to the peak of Ly{\\alpha} line, which has been detected in only a couple of z > 5 LAEs till now. If the broad red wing is ascribed to gas outflow instead of AGN activity, the outflow velocity c...

  5. Spectral classification indicators of emission-line galaxies from the Sloan Digital Sky Survey

    Science.gov (United States)

    Shi, Fei; Liu, Yu-Yan; Li, Pei-Yu; Yu, Ming; Lei, Yu-Ming; Wang, Jian

    2015-07-01

    To find efficient spectral classification diagrams to classify emission-line galaxies, especially in large surveys and huge data bases, an artificial neural network (ANN) supervised learning algorithms is applied to a sample of emission-line galaxies from the Sloan Digital Sky Survey data release 9 provided by the Max Planck Institute and the Johns Hopkins University (MPA/JHU) (http://www.sdss3.org/dr9/spectro/spectroaccess.php). A two-step approach is adopted. (i) The ANN network must be trained with a subset of objects that are known to be active galactic nuclei (AGNs) hosts, composites or star-forming galaxies, treating the strong emission-line flux measurements as input feature vectors in n-dimensional space, where n is the number of strong emission-line flux ratios. (ii) After the network is trained on a sample of galaxies, the remaining galaxies are classified in the automatic test analysis as AGN hosts, composites or star-forming galaxies. We show that the classification diagrams based on the [N II]/Hα versus other emission-line ratio, such as [O III]/Hβ, [Ne III]/[O II], ([O III]λ4959 + [O III]λ5007)/[O III]λ4363, [O II]/Hβ, [Ar III]/[O III], [S II]/Hα, and [O I]/Hα, plus colour, allows us to separate unambiguously AGN hosts, composites or star-forming galaxies. Among them, the diagram of [N II]/Hα versus [O III]/Hβ achieved an accuracy of 98 per cent for classification of AGN hosts, composites or star-forming galaxies. The other diagrams above except the diagram of [N II]/Hα versus [O III]/Hβ give an accuracy of ˜90 per cent. The code in the paper is available on the web (http://fshi5388.blog.163.com).

  6. Identification of emission lines in the low-ionization strontium filament near Eta Carinae

    Science.gov (United States)

    Hartman, H.; Gull, T.; Johansson, S.; Smith, N.; HST Eta Carinae Treasury Project Team

    2004-05-01

    We have obtained deep spectra from 1640 to 10 100 Å with the Space Telescope Imaging Spectrograph (STIS) of the strontium filament, a largely neutral emission nebulosity lying close to the very luminous star Eta Carinae and showing an uncommon spectrum. Over 600 emission lines, both permitted and forbidden, have been identified. The majority originates from neutral or singly-ionized iron group elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Sr is the only neutron capture element detected. The presence of Sr II, numerous strong Ti II and V II lines and the dominance of Fe I over Fe II are notable discoveries. While emission lines of hydrogen, helium, and nitrogen are associable with other spatial structures at other velocities within the Homunculus, no emission lines from these elements correspond to the spatial structure or velocity of the \\ion{Sr} filament. Moreover, no identified \\ion{Sr} filament emission line requires an ionization or excitation energy above approximately 8 eV. Ionized gas extends spatially along the aperture, oriented along the polar axis of the Homunculus, and in velocity around the strontium filament. We suggest that the strontium filament is shielded from ultraviolet radiation at energies above 8 eV, but is intensely irradiated by the central star at wavelengths longward of 1500 Å. Based 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 NAS5-26555. Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/419/215

  7. First redshift determination of an optically/UV faint submillimeter galaxy using CO emission lines

    CERN Document Server

    Weiss, A; Downes, D; Walter, F; Cirasuolo, M; Menten, K M

    2009-01-01

    We report the redshift of a distant, highly obscured submm galaxy (SMG), based entirely on the detection of its CO line emission. We have used the newly commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8 GHz of instantaneous dual-polarization bandwidth, to search the 3-mm atmospheric window for CO emission from SMMJ14009+0252, a bright SMG detected in the SCUBA Lens Survey. A detection of the CO(3--2) line in the 3-mm window was confirmed via observations of CO(5--4) in the 2-mm window. Both lines constrain the redshift of SMMJ14009+0252 to z=2.9344, with high precision (dz=2 10^{-4}). Such observations will become routine in determining redshifts in the era of the Atacama Large Millimeter/submillimeter Array (ALMA).

  8. Weak Emission Line Quasars in the Context of a Modified Baldwin Effect

    CERN Document Server

    Shemmer, Ohad

    2015-01-01

    We investigate the relationship between the rest-frame equivalent width (EW) of the C IV \\lambda1549 broad-emission line, monochromatic luminosity at rest-frame 5100 A, and the Hbeta-based Eddington ratio in a sample of 99 ordinary quasars across the widest possible ranges of redshift (0 ~3 \\sigma\\ level, by exhibiting C IV lines much weaker than predicted from their Hbeta-based Eddington ratios. Assuming the supermassive black-hole masses in all quasars can be determined reliably using the single-epoch Hbeta-method, our results indicate that EW(C IV) cannot depend solely on the Eddington ratio. We briefly discuss a strategy for further investigation into the roles that basic physical properties play in controlling the relative strengths of broad-emission lines in quasars.

  9. Super-massive binary black holes and emission lines in active galactic nuclei

    CERN Document Server

    Popovic, Luka C

    2011-01-01

    The broad emission spectral lines emitted from AGNs are our main probe of the geometry and physics of the broad line region (BLR) close to the SMBH. There is a group of AGNs that emits very broad and complex line profiles, showing two displaced peaks, one blueshifted and one redshifted from the systemic velocity defined by the narrow lines, or a single such peak. It has been proposed that such line shapes could indicate a supermassive binary black hole (SMB) system. We discuss here how the presence of an SMB will affect the BLRs of AGNs and what the observational consequences might be. We review previous claims of SMBs based on broad line profiles and find that they may have non-SMB explanations as a consequence of a complex BLR structure. Because of these effects it is very hard to put limits on the number of SMBs from broad line profiles. It is still possible, however, that unusual broad line profiles in combination with other observational effects (line ratios, quasi-periodical oscillations, spectropolarim...

  10. HST WFC3 Early Release Science: Emission-Line Galaxies from IR Grism Observations

    Science.gov (United States)

    Straughn, A. N.; Kuntschner, H.; Kuemmel, M.; Walsh, J. R.; Cohen, S. H.; Gardner, J. P.; Windhorst, R. A.; O'Connell, R. W.; Pirzkal, N.; Meurer, G.; McCarthy, P. J.; Hathi, N. P.; Malhotra, S.; Rhoads, J.; Balick, B.; Bond, H. E.; Calzetti, D.; Disney, M. J.; Dopita, M. A.; Frogel, J. A.; Hall, D. N. B.; Holtzman, J. A.; Kimlbe, R. A.; Trauger, J. T.; Young, E. T.

    2010-01-01

    We present grism spectra of emission line galaxies (ELGs) from 0.6-1.6 microns from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). These new infrared grism data augment previous optical Advanced Camera for Surveys G800L (0.6-0.95 micron) grism data in GOODS South, extending the wavelength coverage well past the G800L red cutoff. The ERS grism field was observed at a depth of 2 orbits per grism, yielding spectra of hundreds of faint objects, a subset of which are presented here. ELGs are studied via the Ha, [O III ], and [OII] emission lines detected in the redshift ranges 0.2 less than or equal to z less than or equal to 1.6, 1.2 less than or equal to z less than or equal to 2.4 and 2.0 less than or equal to z less than or equal to 3.6 respectively in the G102 (0.8-1.1 microns; R approximately 210) and C141 (1.1-1.6 microns; R approximately 130) grisms. The higher spectral resolution afforded by the WFC3 grisms also reveals emission lines not detectable with the G800L grism (e.g., [S II] and [S III] lines). From these relatively shallow observations, line luminosities, star formation rates, and grism spectroscopic redshifts are determined for a total of 25 ELGs to M(sub AB)(F098M) approximately 25 mag. The faintest source in our sample with a strong but unidentified emission line--is MAB(F098M)=26.9 mag. We also detect the expected trend of lower specific star formation rates for the highest mass galaxies in the sample, indicative of downsizing and discovered previously from large surveys. These results demonstrate the remarkable efficiency and capability of the WFC3 NIR grisms for measuring galaxy properties to faint magnitudes.

  11. Hot surface ionic line emission and cold K-inner shell emission from petawatt-laser irradiated Cu foil targets

    Energy Technology Data Exchange (ETDEWEB)

    Theobald, W; Akli, K; Clarke, R; Delettrez, J A; Freeman, R R; Glenzer, S; Green, J; Gregori, G; Heathcote, R; Izumi, N; King, J A; Koch, J A; Kuba, J; Lancaster, K; MacKinnon, A J; Key, M; Mileham, C; Myatt, J; Neely, D; Norreys, P A; Park, H; Pasely, J; Patel, P; Regan, S P; Sawada, H; Shepherd, R; Snavely, R; Stephens, R B; Stoeckl, C; Storm, M; Zhang, B; Sangster, T C

    2005-12-13

    A hot, T{sub e} {approx} 2- to 3-keV surface plasma was observed in the interaction of a 0.7-ps petawatt laser beam with solid copper-foil targets at intensities >10{sup 20} W/cm{sup 2}. Copper K-shell spectra were measured in the range of 8 to 9 keV using a single-photon-counting x-ray CCD camera. In addition to K{sub {alpha}} and K{sub {beta}} inner-shell lines, the emission contained the Cu He{sub {alpha}} and Ly{sub {alpha}} lines, allowing the temperature to be inferred. These lines have not been observed previously with ultrafast laser pulses. For intensities less than 3 x 10{sup 18} W/cm{sup 2}, only the K{sub {alpha}} and K{sub {beta}} inner-shell emissions are detected. Measurements of the absolute K{sub {alpha}} yield as a function of the laser intensity are in agreement with a model that includes refluxing and confinement of the suprathermal electrons in the target volume.

  12. Startup of Plasma Current in J-TEXT Tokamak Prompted by the Hα Line Emission Criterion

    Institute of Scientific and Technical Information of China (English)

    GAO Li; ZHUANG Ge; HU Xiwei; ZHANG Ming

    2009-01-01

    An Hα line-emission detection system was developed on the joint texas experimental tokamak (J-TEXT), which is used to determine the Hα emission level during the gas breakdown and hereafter to control the startup of the plasma current. The detector consists of an Hα in-terference filter, a focusing lens, a photodiode and a preamplifier. In the J-TEXT operation, the Hα emission is taken as a monitor signal which is highly sensitive to the generation of a plasma.Furthermore, the power supply control system using the above signal as an input is capable of de-termining whether and when to fire the Ohmic heating capacitor banks, which are applied to drive the plasma current ramp-up. The experimental results confirm that the Hα emission criterion is acceptable for controlling the plasma current promotion in the J-TEXT tokamak.

  13. STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS

    International Nuclear Information System (INIS)

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  14. Strong Field Effects on Emission Line Profiles: Kerr Black Holes and Warped Accretion Disks

    Science.gov (United States)

    Wang, Yan; Li, Xiang-Dong

    2012-01-01

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  15. Line Emission from an Accretion Disk around a Black hole Effects of Disk Structure

    CERN Document Server

    Pariev, V I; Pariev, Vladimir I.; Bromley, Benjamin C.

    1998-01-01

    The observed iron K-alpha fluorescence lines in Seyfert-1 galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. These lines serve as powerful probes for examining the structure of inner regions of accretion disks. Previous studies of line emission have considered geometrically thin disks only, where the gas moves along geodesics in the equatorial plane of a black hole. Here we extend this work to consider effects on line profiles from finite disk thickness, radial accretion flow and turbulence. We adopt the Novikov and Thorne (1973) solution, and find that within this framework, turbulent broadening is the dominant new effect. The most prominent change in the skewed, double-horned line profiles is a substantial reduction in the maximum flux at both red and blue peaks. The effect is most pronounced when the inclination angle is large, and when the accretion rate is high. Thus, the effects discussed here may be important for future detailed model...

  16. Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bulbul, Esra; Foster, Adam; Smith, Randall K.; Randall, Scott W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Markevitch, Maxim [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Loewenstein, Michael, E-mail: ebulbul@cfa.harvard.edu [CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-01

    We detect a weak unidentified emission line at E = (3.55-3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN 'all others' spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50-110 eV of several known lines. The detection is at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with m{sub s} = 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar XVII dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10-20. Confirmation with Astro-H will be critical to determine the nature of this new line.

  17. Oxygen emission line properties from analysis of MAVEN-IUVS Echellograms of the Martian atmosphere

    Science.gov (United States)

    Mayyasi, Majd A.; Clarke, John T.; Stewart, Ian; McClintock, William; Schneider, Nicholas M.; Jakosky, Bruce; IUVS Team

    2016-10-01

    The high resolution echelle mode of the Mars Atmosphere and Volatile Evolution (MAVEN) mission Imaging Ultraviolet Spectrograph (IUVS) instrument has been used to spectrally image the sunlit limb of Mars during the spacecraft periapse orbital segments. When multiple images are co-added over a few hours, there are detectable spectral emission features that have been identified to originate from atomic and molecular neutral species such as H, D, N, O, CO as well as from C+ ions. The echelle detector has a localized spectral resolution of ~0.008 Angstrom and is therefore capable of spectrally resolving the oxygen resonant triplet (130.217, 130.486 and 130.603 nm) and forbidden doublet (135.560 and 135.851 nm) emission lines. The brightness of each of these emission lines has been determined and will be compared with detected brightnesses of other species. The emission line integrated brightness ratios are being analyzed for insights into the abundance, excitation, and variability of oxygen in the martian atmosphere.

  18. Laboratory Measurements of Fe XXIV Line Emission: 3-->2 Transitions near Excitation Threshold

    Science.gov (United States)

    Gu, M. F.; Kahn, S. M.; Savin, D. W.; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Reed, K. J.; Bhalla, C. P.; Grabbe, S. R.

    1999-06-01

    Using the Electron Beam Ion Trap facility at Lawrence Livermore National Laboratory, we have measured relative cross sections for Fe XXIV line emission at electron energies between 0.7 and 3.0 keV. The measurements include line formation by direct electron impact excitation (DE), radiative cascades, resonant excitation (RE), and dielectronic recombination (DR) satellites with captured electrons in n>=5 levels. Good agreement with R-matrix and distorted wave calculations is found. In collisionally ionized plasmas, at temperatures near where the ion abundance peaks (kTe~1.7 keV), the RE contributions arefound to be emission, while the DR satellites contribute atomic physics calculations is found, there is less good agreement with existingspectral synthesis codes in common astrophysical use. For the Fe XXIV 3p3/2-->2s1/2, 3p1/2-->2s1/2, and 3d5/2-->2p3/2 transitions, the synthesis code MEKAL underestimates the emissivity in coronal equilibrium by ~20% at temperatures near where the ion abundance peaks. In situations where the ionization balance is not solely determined by the electron temperature, RE and DR satellites may contribute a considerable fraction of the line emission.

  19. The Nature of Active Galactic Nuclei with Velocity Offset Emission Lines

    CERN Document Server

    Müller-Sánchez, Francisco; Stern, Daniel; Harrison, Fiona A

    2016-01-01

    We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field spectroscopy to probe the morphology and kinematics of the ionized gas in four velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey. These objects possess optical emission lines that are offset in velocity from systemic as measured from stellar absorption features. At a resolution of ~0.18", OSIRIS allows us to distinguish which velocity offset emission lines are produced by the motion of an AGN in a dual supermassive black hole system, and which are produced by outflows or other kinematic structures. In three galaxies, J1018+2941, J1055+1520 and J1346+5228, the spectral offset of the emission lines is caused by AGN-driven outflows. In the remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that contains the peak of Pa$\\alpha$ emission 0.2" from the center of the galaxy. The most plausible explanation for the origin of this spatially and kinematically offset peak is that it is a region of en...

  20. 40 CFR 1042.320 - What happens if one of my production-line engines fails to meet emission standards?

    Science.gov (United States)

    2010-07-01

    ...-line engines fails to meet emission standards? 1042.320 Section 1042.320 Protection of Environment... if one of my production-line engines fails to meet emission standards? (a) If you have a production... an initial failed test if all of the following are true: (1) The catalyst was in a green...

  1. IUE observations of the Henize-Carlson sample of peculiar emission line supergiants: The galactic analogs of the Magellanic Zoo

    Science.gov (United States)

    Shore, Steven N.; Brown, Douglas N.; Sanduleak, N.

    1986-01-01

    Some 15 stars from the Carlson-Henize survey of southern peculiar emission line stars were studied. From both the optical and UV spectra, they appear to be galactic counterparts of the most extreme early-type emission line supergiants of the Magellanic Clouds.

  2. The VLT-FLAMES Tarantula survey. XX. The nature of the X-ray bright emission-line star VFTS 399

    Science.gov (United States)

    Clark, J. S.; Bartlett, E. S.; Broos, P. S.; Townsley, L. K.; Taylor, W. D.; Walborn, N. R.; Bird, A. J.; Sana, H.; de Mink, S. E.; Dufton, P. L.; Evans, C. J.; Langer, N.; Maíz Apellániz, J.; Schneider, F. R. N.; Soszyński, I.

    2015-07-01

    Context. The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. Aims: One member of this group, the late O-type star VFTS 399, is found to be unexpectedly X-ray bright for its bolometric luminosity - in this study we aim to determine its physical nature and the cause of this behaviour. Methods: To accomplish this we performed a time-resolved analysis of optical, infrared and X-ray observations. Results: We found VFTS 399 to be an aperiodic photometric variable with an apparent near-IR excess. Its optical spectrum demonstrates complex emission profiles in the lower Balmer series and select He i lines - taken together these suggest an OeBe classification. The highly variable X-ray luminosity is too great to be produced by a single star, while the hard, non-thermal nature suggests the presence of an accreting relativistic companion. Finally, the detection of periodic modulation of the X-ray lightcurve is most naturally explained under the assumption that the accretor is a neutron star. Conclusions: VFTS 399 appears to be the first high-mass X-ray binary identified within 30 Dor, sharing many observational characteristics with classical Be X-ray binaries. Comparison of the current properties of VFTS 399 to binary-evolution models suggests a progenitor mass ≳25 M⊙ for the putative neutron star, which may host a magnetic field comparable in strength to those of magnetars. VFTS 399 is now the second member of the cohort of rapidly rotating "single" O-type stars in 30 Dor to show evidence of binary interaction resulting in spin-up, suggesting that this may be a viable evolutionary pathway for the formation of a subset of this stellar population. Based on observations collected at the European Southern Observatory under program ID 182.D-0222.

  3. FIRST DETECTION OF NEAR-INFRARED LINE EMISSION FROM ORGANICS IN YOUNG CIRCUMSTELLAR DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Mandell, Avi M.; Mumma, Michael J.; Villanueva, Geronimo [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bast, Jeanette; Van Dishoeck, Ewine F. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Blake, Geoffrey A. [California Institute of Technology, Division of Geological and Planetary Sciences, MS 150-21, Pasadena, CA 91125 (United States); Salyk, Colette, E-mail: Avi.Mandell@nasa.gov [Department of Astronomy, University of Texas, Austin, TX 78712 (United States)

    2012-03-10

    We present an analysis of high-resolution spectroscopy of several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope, revealing the first detections of emission from HCN and C{sub 2}H{sub 2} in circumstellar disks at near-infrared wavelengths. Using advanced data reduction techniques, we achieve a dynamic range with respect to the disk continuum of {approx}500 at 3 {mu}m, revealing multiple emission features of H{sub 2}O, OH, HCN, and C{sub 2}H{sub 2}. We also present stringent upper limits for two other molecules thought to be abundant in the inner disk, CH{sub 4} and NH{sub 3}. Line profiles for the different detected molecules are broad but centrally peaked in most cases, even for disks with previously determined inclinations of greater than 20 Degree-Sign , suggesting that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We apply two different modeling strategies to constrain the molecular abundances and temperatures: we use a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we compare these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU).

  4. The DEEP2 Galaxy Redshift Survey: Redshift Identification of Single-Line Emission Galaxies

    CERN Document Server

    Kirby, E N; Faber, S M; Koo, D C; Weiner, B J; Cooper, M C

    2007-01-01

    We present two methods for determining spectroscopic redshifts of galaxies in the \\deep survey which display only one identifiable feature, an emission line, in the observed spectrum ("single-line galaxies"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: Halpha, [OIII] 5007, Hbeta, or [OII] 3727. Then, we supplement spectral information with BRI photometry. The first method, parameter space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B-R), (R-I), R, observed wavelength parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [OII] doublets. Of the lines identified as Halpha in the PSP and ANN methods, 91.4% and 94.2% respectively are accurate. Although the methods are no...

  5. A New Diagnostic Diagram of Ionization Source for High Redshift Emission Line Galaxies

    CERN Document Server

    Zhang, Kai

    2016-01-01

    We propose a new diagram, the Kinematic-Excitation diagram (KEx diagram), which uses the [OIII]/H\\beta\\ line ratio and the [OIII]5007 emission line width (\\sigma_{[OIII]}) to diagnose the ionization source and physical properties of the Active Galactic Nuclei (AGNs) and the star-forming galaxies (SFGs). The KEx diagram is a suitable tool to classify emission-line galaxies (ELGs) at intermediate redshift because it uses only the [OIII]5007 and H\\beta\\ emission lines. We use the SDSS DR7 main galaxy sample and the Baldwin-Phillips-Terlevich (BPT) diagnostic to calibrate the diagram at low redshift. We find that the diagram can be divided into 3 regions: one occupied mainly by the pure AGNs (KEx-AGN region), one dominated by composite galaxies (KEx-composite region), and one contains mostly SFGs (KEx-SFG region). AGNs are separated from SFGs in this diagram mainly because they preferentially reside in luminous and massive galaxies and have high [OIII]/H\\beta. The separation of AGN from star-forming galaxies is e...

  6. Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

    CERN Document Server

    Dietrich, M; Hamann, F; Heidt, J; Jäger, K; Vestergaard, M; Wagner, S J

    2003-01-01

    We present observations of 11 high redshift quasars ($3.9 \\la z \\la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\\odot = 4.3 \\pm 0.3$. Assuming a chemical evolution time scale of $\\tau_{evol} \\simeq 0.5 - 0.8$ Gyrs, we derive a redshift of $z_f \\simeq 6 {\\rm to} 8$ for the onset of the first major star formation episode (H$_o = 65$ km s$^{-1}$ Mpc$^{-1}$, $\\Omega_M = 0.3$, $\\Omega_\\Lambda = 0.7$), corresponding to an age of the universe of several $10^8$ yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe...

  7. The Deepest Spectrum in the Universe? Line Emission from Lyman-alpha Clouds at z 3

    Science.gov (United States)

    Bunker, Andrew J.; Rauch, M.; Haehnelt, M.; Becker, G.; Marleau, F.; Graham, J.; Research, European; Inter-Galactic Medium, Training Network on the

    2007-12-01

    We present the results of an extremely deep long-slit optical spectroscopic search for low-luminosity Lyman-alpha emitters. Over several years we have accumulated 150-hours integration on a single field with 8-10m telescopes (VLT/FORS2, Gemini/GMOS and Keck/LRIS) at a spectral resolution of 300km/s. This is the deepest spectrum ever obtained - our 1 sigma sensitivity to line emission in a 1 arcsec2 aperture is 1019erg/cm2/s. We have significant detections of 30 emission line objects, which are most likely Lyman-alpha emitters at 2.7line emission may be powered by star formation in conditions of low metallicity and low dust, or alternatively may arise from cooling radiation or perhaps external photoionzation by the metagalactic Lyman continuum background. Many of the line emitters are significantly spatially extended (with median size 4arcsec, 30kpc) and could plausibly be the host population of the high column density Lyman-alpha absorption clouds seen in QSO spectra (the Damped Lyman-alpha Systems and the Lyman-Limit Systems).

  8. Ca II H and K Chromospheric Emission Lines in Late K and M Dwarfs

    CERN Document Server

    Rauscher, E; Marcy, Geoffrey W.; Rauscher, Emily

    2006-01-01

    We have measured the profiles of the Ca II H and K chromospheric emission lines in 147 main sequence stars of spectral type M5-K7 (0.30-0.55 solar masses) using multiple high resolution spectra obtained during six years with the HIRES spectrometer on the Keck 1 telescope. Remarkably, the average FWHM, equivalent widths, and line luminosities of Ca II H and K increase by a factor of 3 with increasing stellar mass over this small range of stellar masses. We fit the H and K lines with a double Gaussian model to represent both the chromospheric emission and the non-LTE central absorption. Most of the sample stars display a central absorption that is typically redshifted by ~0.1 km/s relative to the emission, but the nature of this velocity gradient remains unknown. The FWHM of the H and K lines increase with stellar luminosity, reminiscent of the Wilson-Bappu effect in FGK-type stars. Both the equivalent widths and FWHM exhibit modest temporal variability in individual stars. At a given value of M_v, stars exhibi...

  9. ALMA Imaging of the CO (6-5) Line Emission in NGC 7130*

    Science.gov (United States)

    Zhao, Yinghe; Lu, Nanyao; Xu, C. Kevin; Gao, Yu; Barcos-Munõz, Loreto; Díaz-Santos, Tanio; Appleton, Philip; Charmandaris, Vassilis; Armus, Lee; van der Werf, Paul; Evans, Aaron; Cao, Chen; Inami, Hanae; Murphy, Eric

    2016-04-01

    In this paper, we report our high-resolution (0.″20 × 0.″14 or ∼70 × 49 pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 μm dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are 1230 ± 74 Jy km s‑1 and 814 ± 52 mJy, respectively, which account for 100% and 51% of their total fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of ∼70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an active galactic nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-α maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of Universities, Inc.

  10. K-shell Emission of Neutral Iron Line from Sgr B2 Excited by Subrelativistic Protons

    CERN Document Server

    Dogiel, Vladimir; Koyama, Katsuji; Nobukawa, Masayoshi; Cheng, Kwong-Sang

    2011-01-01

    We investigated the emission of K$\\alpha$ iron line from the massive molecular clouds in the Galactic center (GC). We assume that at present the total flux of this emission consists of time variable component generated by primary X-ray photons ejected by Sagittarius A$^\\ast$ (Sgr A$^\\ast$) in the past and a relatively weak quasi-stationary component excited by impact of protons which were generated by star accretion onto the central black hole. The level of background emission was estimated from a rise of the 6.4 keV line intensity in the direction of several molecular clouds, that we interpreted as a stage when the X-ray front ejected by Sgr A$^\\ast$ entered into these clouds. The 6.4 keV emission before this intensity jump we interpreted as emission generated by subrelativistic cosmic rays there. The cross-section of K$\\alpha$ vacancies produced by protons differs from that of electrons or X-rays. Therefore, we expect that this processes can be distinguished from the analysis of the equivalent width of the ...

  11. Development of a Temperature Diagnostic Based on the Emission Lines of Fluorine-Like Ions

    Science.gov (United States)

    Lepson, Jaan K.; Beiersdorfer, Peter; Kaita, Robert; Majeski, Richard; Boyle, Dennis

    2016-06-01

    We used the Flexible Atomic Code to calculate theoretical intensities of extreme ultraviolet emission lines of fluorine-like Al IV, Si VI, and S VIII at electron temperatures Te from 1 eV to well above 100 eV, and found that the intensity ratio of the 3-->2 and 2-->2 transitions is temperature sensitive. We tested these calculations by measuring the relevant Al IV emission in the 115-320 Å spectral region on the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory. Spectra were taken with the Long Wavelength Extreme Ultraviolet Spectrometer, LoWEUS, which has a resolution of ~0.3 Å. We identified emission from neon-like Al V as well as fluorine-like Al IV. Our data include emission from Li II and Li III, and O IV-VI, which we used for wavelength calibration. We used the oxygen line intensities from CHIANTI to calculate the intensity response function for the region we studied. The measurements confirm that the ratio of the intensity of the 3-->2 feature at 133 Å to a pair of 2-->2 lines at 278 Å and 281 Å can be used to derive temperature estimates for the emitting region of the plasma. Our measurements indicate a temperature Te of ~16 ± 2 eV from the 133/278 Å line pair and ~17.5 ±2 eV from the 133/281 Å line pair, which is close to the temperature of maximum abundance of fluorine-like Al.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the U.S. Department of Energy Basic Plasma Science Program.

  12. Mid-infrared [NeII] line emission from the nucleus of NGC 253

    CERN Document Server

    Böker, T; Storey, J W V

    1998-01-01

    We report on mid-infrared (MIR) continuum and line emission mapping of the nucleus of NGC 253. The data, with a resolution of 1\\as.4, reveal a double-peaked arc-like [NeII] emission region. Comparison with published data shows that the [NeII] arc is centered on the nucleus of the galaxy. The brightest [NeII] source coincides with the infrared continuum peak. The interpretation of these results is complicated by the edge-on orientation of NGC 253, but a self-consistent explanation is starformation triggered by dynamical resonances in a barred potential.

  13. First MERLIN Observations of Line Emission from the OH Megamaser toward IRAS 10173+0828

    Institute of Scientific and Technical Information of China (English)

    Zhi-Yao Yu

    2005-01-01

    Many galaxies are thought to contain massive black holes, with masses in excess of ten million solar masses, at their centres and warped circumnuclear toruses. The best evidence comes from observing gas or masers rotating rapidly within a circumnuclear torus surrounding a central body. Here we report on the first MERLIN observations of line emission from the OH megamaser toward IRAS 10173+0828. The position of peak flux contours of the OH megamaser is consistent with that of the continuum in IRAS 10173+0828. This means that the OH megamaser is a diffuse unsaturated maser which could amplify the diffuse 18 cm continuum emission with an amplification factor of order unity.

  14. Integrated Spectroscopy of the Herschel Reference Survey. The spectral line properties of a volume-limited, K-band selected sample of nearby galaxies

    CERN Document Server

    Boselli, A; Cortese, L; Gavazzi, G; Buat, V

    2012-01-01

    We present long-slit integrated spectroscopy of 238 late-type galaxies belonging to the Herschel Reference Survey, a volume limited sample representative of the nearby universe. This sample has a unique legacy value since ideally defined for any statistical study of the multifrequency properties of galaxies spanning a large range in morphological type and luminosity. The spectroscopic observations cover the spectral range 3600-6900 A at a resolution R ~ 1000 and are thus suitable for separating the underlying absorption from the emission of the Hbeta line as well as the two [NII] lines from the Halpha emission. We measure the fluxes and the equivalent widths of the strongest emission lines ([OII], Hbeta, [OIII], [NII], Halpha, and [SII]). The data are used to study the distribution of the equivalent width of all the emission lines, of the Balmer decrement C(Hbeta) and of the observed underlying Balmer absorption under Hbeta in this sample. Combining these new spectroscopic data with those available at other f...

  15. Be phenomenon in open clusters: Results from a survey of emission-line stars in young open clusters

    OpenAIRE

    Mathew, B.; Subramaniam, A.; Bhatt, B. C.

    2008-01-01

    Emission-line stars in young open clusters are identified to study their properties, as a function of age, spectral type and their evolutionary state. 207 open star clusters were observed using slitless spectroscopy method and 157 emission stars were identified in 42 clusters. We have found 54 new emission-line stars in 24 open clusters, out of which 19 clusters are found to house emission stars for the first time. About 20% clusters harbour emission stars. The fraction of clusters housing em...

  16. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves

    CERN Document Server

    Barth, A J; Canalizo, G; Filippenko, A V; Gates, E L; Greene, J E; Li, W; Malkan, M A; Pancoast, A; Sand, D J; Stern, D; Treu, T; Woo, J -H; Assef, R J; Bae, H -J; Brewer, B J; Cenko, S B; Clubb, K I; Cooper, M C; Diamond-Stanic, A M; Hiner, K D; Hoenig, S F; Hsiao, E; Kandrashoff, M T; Lazarova, M S; Nierenberg, A M; Rex, J; Silverman, J M; Tollerud, E J; Walsh, J L

    2015-01-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the AGN continuum, and measurements of the broad H-beta line widths in mean and root-mean square (rms) spectra. For the most highly variable AGNs we also measured broad H-beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H-beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H-beta ve...

  17. LZIFU: an emission-line fitting toolkit for integral field spectroscopy data

    Science.gov (United States)

    Ho, I.-Ting; Medling, Anne M.; Groves, Brent; Rich, Jeffrey A.; Rupke, David S. N.; Hampton, Elise; Kewley, Lisa J.; Bland-Hawthorn, Joss; Croom, Scott M.; Richards, Samuel; Schaefer, Adam L.; Sharp, Rob; Sweet, Sarah M.

    2016-09-01

    We present lzifu (LaZy-IFU), an idl toolkit for fitting multiple emission lines simultaneously in integral field spectroscopy (IFS) data. lzifu is useful for the investigation of the dynamical, physical and chemical properties of gas in galaxies. lzifu has already been applied to many world-class IFS instruments and large IFS surveys, including the Wide Field Spectrograph, the new Multi Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area (CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail the structure of the toolkit, and how the line fluxes and flux uncertainties are determined, including the possibility of having multiple distinct kinematic components. We quantify the performance of lzifu, demonstrating its accuracy and robustness. We also show examples of applying lzifu to CALIFA and SAMI data to construct emission line and kinematic maps, and investigate complex, skewed line profiles presented in IFS data. The code is made available to the astronomy community through github. lzifu will be further developed over time to other IFS instruments, and to provide even more accurate line and uncertainty estimates.

  18. Line emission from an accretion disk around black hole effects of the disk structure

    CERN Document Server

    Pariev, V I; Bromley, Benjamin C.; Pariev, Vladimir I.

    1998-01-01

    The observed iron K-alpha fluorescence lines in Seyfert galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. Previous studies of line emission have considered only geometrically thin disks, where the gas moves along geodesics in the equatorial plane of a black hole. Here we extend this work to include effects on line profiles from finite disk thickness, radial accretion flow and turbulence. We adopt the Novikov-Thorne solution, and find that within this framework, turbulent broadening is the most significant effect. The most prominent changes in the skewed, double-horned line profiles is a substantial reduction in the maximum flux at both red and blue peaks. We show that at the present level of signal-to-noise in X-ray spectra, proper treatment of the actual structure of the accretion disk can change estimates of the inclination angle of the disk. Thus these effects will be important for future detailed modeling of high quality observational d...

  19. BROAD Hβ EMISSION-LINE VARIABILITY IN A SAMPLE OF 102 LOCAL ACTIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Runco, Jordan N.; Cosens, Maren; Bennert, Vardha N.; Scott, Bryan [Physics Department, California Polytechnic State University, San Luis Obispo CA 93407 (United States); Komossa, S. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany); Malkan, Matthew A.; Treu, Tommaso [Department of Physics, University of California, Los Angeles, CA 90095 (United States); Lazarova, Mariana S. [Department of Physics and Physical Science, University of Nebraska Kearney, Kearney, NE 68849 (United States); Auger, Matthew W. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Park, Daeseong, E-mail: jrunco@calpoly.edu, E-mail: mcosens@calpoly.edu, E-mail: vbennert@calpoly.edu, E-mail: malkan@astro.ucla.edu, E-mail: tt@physics.ucsb.edu, E-mail: lazarovam2@unk.edu, E-mail: mauger@ast.cam.ac.uk, E-mail: daeseongpark@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon, 34055 (Korea, Republic of)

    2016-04-10

    A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses M{sub BH} > 10{sup 7}M{sub ⊙} was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M{sub BH} and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate M{sub BH}, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (∼66%) of the objects, resulting in a Seyfert-type change for ∼38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hβ line virtually disappears in 3/102 (∼3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study provides statistical information on the frequency of Hβ line variability in a sample of low-redshift Seyfert galaxies.

  20. The merger Seyfert galaxy Arp 220. Line and continuum absorption and emission

    CERN Document Server

    Contini, M

    2012-01-01

    The line and continuum spectra of the merger galaxy Arp 220 are analysed with the aim of investigating the ionizing and heating sources. We refer to radio, optical, infrared and X-ray spectra. The results show that in agreement with other merger galaxies, the optical lines are emitted from gas photoionised by the AGN and heated by the shocks in the extended NLR. The infrared lines are better explained by the emission from gas close to the starburst. The starburst dominates the infrared emission. [OI] and [CI] lines in the far-infrared are formed in the internal region of extended clouds and are therefore absorbed, while [CII] lines are emitted from the external edges of outflowing clouds. The O/H relative abundances are about solar and N/H are higher than solar by a factor of 1.5, throughout the starburst region, while in the AGN extended NLR the O/H ratio is half solar. A relatively high dust-to-gas ratio is indicated by modelling the dust reprocessed radiation peak consistently with bremsstrahlung emitted f...

  1. On the thermal line emission from the outflows in ultraluminous X-ray sources

    OpenAIRE

    Xu, Ya-Di; Cao, Xinwu

    2016-01-01

    The atomic features in the X-ray spectra of the ultraluminous X-ray source (ULX) may be associated with the outflow (Middleton et al. 2015), which may provide a way to explore the physics of the ULXs. We construct a conical outflow model, and calculate the thermal X-ray Fe emission lines from the outflows. Our results show that thermal line luminosity decreases with increasing outflow velocity or/and opening angle of the outflow for a fixed kinetic power of the outflows. Assuming the kinetic ...

  2. Resonance scattering in the X-ray emission lines profiles of ζ Puppis

    OpenAIRE

    Leutenegger, M. A.; Cohen, D. H.; Kahn, S. M.; Owocki, S. P.; Paerels, F. B. S.

    2008-01-01

    We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star ζ Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombi...

  3. Resonance scattering in the X-ray emission line profiles of Zeta Puppis

    OpenAIRE

    Leutenegger, M. A.; Cohen, D. H.; Kahn, S. M.; Owocki, S. P.; Paerels, F. B. S.

    2007-01-01

    We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star Zeta Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the interco...

  4. Confirmation of Small Dynamical and Stellar Masses for Extreme Emission Line Galaxies at z~2

    CERN Document Server

    Maseda, Michael V; da Cunha, Elisabete; Rix, Hans-Walter; Pacifici, Camilla; Momcheva, Ivelina; Brammer, Gabriel B; Franx, Marijn; van Dokkum, Pieter; Bell, Eric F; Fumagalli, Mattia; Grogin, Norman A; Kocevski, Dale D; Koekemoer, Anton M; Lundgren, Britt F; Marchesini, Danilo; Nelson, Erica J; Patel, Shannon G; Skelton, Rosalind E; Straughn, Amber N; Trump, Jonathan R; Weiner, Benjamin J; Whitaker, Katherine E; Wuyts, Stijn

    2013-01-01

    Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (~50 km/s) for a sample of 14 Extreme Emission Line Galaxies (EELGs) at redshifts 1.4 1. The stellar mass formed in this vigorous starburst phase represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.

  5. Emission Signatures from Sub-parsec Binary Supermassive Black Holes I: Diagnostic Power of Broad Emission Lines

    CERN Document Server

    Nguyen, Khai

    2016-01-01

    Motivated by advances in observational searches for sub-parsec supermassive black hole binaries (SBHBs) made in the past few years we develop a semi-analytic model to describe spectral emission line signatures of these systems. The goal of this study is to aid the interpretation of spectroscopic searches for binaries and help test one of the leading models of binary accretion flows in the literature: SBHB in a circumbinary disk. In this work we present the methodology and a comparison of the preliminary model with the data. We model SBHB accretion flows as a set of three accretion disks: two mini-disks that are gravitationally bound to the individual black holes and a circumbinary disk. Given a physically motivated parameter space occupied by sub-parsec SBHBs, we calculate a synthetic database of nearly 15 million broad optical emission line profiles and explore the dependence of the profile shapes on characteristic properties of SBHBs. We find that the modeled profiles show distinct statistical properties as...

  6. The Diverse Nature of Optical Emission Lines in Brightest Cluster Galaxies: IFU Observations of the Central Kiloparsecs

    CERN Document Server

    Edwards, L O V; Mollá, M; McGee, S L

    2009-01-01

    We present integral field spectroscopy of the nebular line emission in a sample of 9 brightest cluster galaxies (BCGs). The sample was chosen to probe both cooling flow and non-cooling flow clusters, as well as a range of cluster X-ray luminosities. The line emission morphology and velocity gradients suggest a great diversity in the properties of the line emitting gas. While some BGCs show evidence for filamentary or patchy emission (Abell 1060, Abell 1668 and MKW3s), others have extended emission (Abell 1204, Abell 2199), while still others have centrally concentrated emission (Abell 2052). We examine diagnostic line ratios to determine the dominant ionization mechanisms in each galaxy. Most of the galaxies show regions with AGN-like spectra, however for two BCGs, Abell 1060 and Abell 1204, the emission line diagnostics suggest regions which can be described by the emission from young stellar populations. The diversity of emission line properties in our sample of BCGs suggests that the emission mechanism is ...

  7. Chemical Abundances in Broad Emission Line Regions The "Nitrogen-Loud" QSO 0353-383

    CERN Document Server

    Baldwin, J A; Korista, K T; Ferland, G J; Dietrich, M; Warner, C

    2003-01-01

    The intensity of the strong N V 1240 line relative to C IV 1549 or to He II 1640 has been proposed as an indicator of the metallicity of QSO broad emission line regions, allowing abundance measurements in a large number of QSOs out to the highest redshifts. Previously, it had been shown that the (normally) much weaker lines N III] 1750 and N IV] 1486 could be used in the same way. The redshift 1.96 QSO 0353-383 has long been known to have N III] and N IV] lines that are far stronger relative to Ly-alpha or C IV than in any other QSO. Because in this particular case these intercombination lines can be easily measured, this unusual object provides an ideal opportunity for testing whether the N V line is a valid abundance indicator. Using new observations of Q0353-383 made both with HST in the ultraviolet and from the ground in the visible passband, we find that intensity ratios involving the strengths of N V, N IV] and N III] relative to lines of He, C and O all indicate that nitrogen is overabundant relative t...

  8. The unusually strong coronal emission lines of SDSS J1055+5637

    CERN Document Server

    Winkler, Hartmut

    2016-01-01

    Many Seyfert galaxies display weak 'coronal' emission features corresponding to [Fe VII], [Fe XI] and [Fe XIV] in their optical spectra, whereas elsewhere these lines seem to be entirely absent. These lines appear to highlight zones in the nucleus irradiated by high-energy photons. The presence of these zones and the conditions therein as determined by the relative line strengths and profiles impose important constraints on the physical models of active galactic nuclei, and Seyferts in particular. In 2009 the discovery was announced of the highly unusual spectrum of SDSS J0952+2143, where the coronal lines are exceptionally strong. This paper presents a second object with abnormally strong coronal features, SDSS J1055+5637. The spectrum, line ratios and related parameters are compared to those of SDSS J0952+2143, three AGN with moderate coronal lines and one where the coronal lines are missing altogether. Possible mechanisms are discussed that may account for the stronger than usual coronal features.

  9. Analysis of Balmer Profiles of early type stars

    CERN Document Server

    Molla, M; Alvarez, M A; González-Delgado, R M; Molla, Mercedes; Diaz, Angeles I.; Alvarez, Mar Alvarez; Delgado, Rosa Gonzalez

    2000-01-01

    The spectral energy distribution (SED) of recent star formation regions isdominated by the more massive and early stars (O and B types). These stars showlarge and very significant absorption features, the most prominent being therecombination lines of H, HeI and HeII. In particular, the shape of theirprofiles are very dependent on the luminosity of the star. We have explored thepotential use of high resolution profiles to discriminate between differentluminosity classes and spectral types, by using profiles of the He and Balmerlines. We have calculated growth curves for each of the lines and theirdependence on gravity and effective temperature. We show some of thesetheoretical growth curves and our preliminary conclusions are analyzed anddiscussed.

  10. Using an Artificial Neural Network to Classify Multi-component Emission Line Fits

    CERN Document Server

    Hampton, Elise J; Medling, Anne; Davies, Rebecca; Dopita, Mike; Ho, I-Ting; Kaasinen, Melanie; Kewley, Lisa; Leslie, Sarah; Sharp, Rob; Sweet, Sarah M; Thomas, Adam D

    2016-01-01

    We present The Machine, an artificial neural network (ANN) capable of differentiating between the numbers of Gaussian components needed to describe the emission lines of Integral Field Spectroscopic (IFS) observations. Here we show the preliminary results of the S7 first data release (Siding Spring Southern Seyfert Spectro- scopic Snapshot Survey, Dopita et al. 2015) and SAMI Galaxy Survey (Sydney-AAO Multi-object Integral Field Unit, Croom et al. 2012) to classify whether the emission lines in each spatial pixel are composed of 1, 2, or 3 different Gaussian components. Previously this classification has been done by individual people, taking an hour per galaxy. This time investment is no longer feasible with the large spectroscopic surveys coming online.

  11. A Search for "Dwarf" Seyfert Nuclei. VI. Properties of Emission-Line Nuclei in Nearby Galaxies

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    2003-01-01

    We use the database from Paper III to quantify the global and nuclear properties of emission-line nuclei in the Palomar spectroscopic survey of nearby galaxies. We show that the host galaxies of Seyferts, LINERs, and transition objects share remarkably similar large-scale properties and local environments. The distinguishing traits emerge on nuclear scales. Compared with LINERs, Seyfert nuclei are an order of magnitude more luminous and exhibit higher electron densities and internal extinction. We suggest that Seyfert galaxies possess characteristically more gas-rich circumnuclear regions, and hence a more abundant fuel reservoir and plausibly higher accretion rates. The differences between the ionization state of the narrow emission-line regions of Seyferts and LINERs can be partly explained by the differences in their nebular properties. Transition-type objects are consistent with being composite (LINER/\\hii) systems. With very few exceptions, the stellar population within the central few hundred parsecs of...

  12. Interpreting the Ionization Sequence in Star-Forming Galaxy Emission-Line Spectra

    CERN Document Server

    Richardson, Chris T; Baldwin, Jack A; Hewett, Paul C; Ferland, Gary J; Crider, Anthony; Meskhidze, Helen

    2016-01-01

    High ionization star forming (SF) galaxies are easily identified with strong emission line techniques such as the BPT diagram, and form an obvious ionization sequence on such diagrams. We use a locally optimally emitting cloud model to fit emission line ratios that constrain the excitation mechanism, spectral energy distribution, abundances and physical conditions along the star-formation ionization sequence. Our analysis takes advantage of the identification of a sample of pure star-forming galaxies, to define the ionization sequence, via mean field independent component analysis. Previous work has suggested that the major parameter controlling the ionization level in SF galaxies is the metallicity. Here we show that the observed SF- sequence could alternatively be interpreted primarily as a sequence in the distribution of the ionizing flux incident on gas spread throughout a galaxy. Metallicity variations remain necessary to model the SF-sequence, however, our best models indicate that galaxies with the hig...

  13. A general catalogue of molecular hydrogen emission-line objects (MHOs) in outflows from young stars

    Science.gov (United States)

    Davis, C. J.; Gell, R.; Khanzadyan, T.; Smith, M. D.; Jenness, T.

    2010-02-01

    We present a catalogue of Molecular Hydrogen emission-line Objects (MHOs) in outflows from young stars, most of which are deeply embedded. All objects are identified in the near-infrared lines of molecular hydrogen, all reside in the Milky Way, and all are associated with jets or molecular outflows. Objects in both low and high-mass star forming regions are included. This catalogue complements the existing database of Herbig-Haro objects; indeed, for completeness, HH objects that are detected in H2 emission are included in the MHO catalogue. http://www.jach.hawaii.edu/UKIRT/MHCat/ Tables A.1 to A.15 are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/511/A24

  14. Evolving Starburst Modeling of FIR/sub-mm/mm Line Emission. II. Application to M 82

    CERN Document Server

    Yao, Lihong

    2009-01-01

    We present starburst models for far-infrared/sub-millimeter/millimeter (FIR/sub-mm/mm) line emission of molecular and atomic gas in an evolving starburst region, which is treated as an ensemble of non-interacting hot bubbles which drive spherical shells of swept-up gas into a surrounding uniform gas medium. These bubbles and shells are driven by stellar winds and supernovae within massive star clusters formed during an instantaneous starburst. The underlying stellar radiation from the evolving clusters affects the properties and structure of photodissociation regions (PDRs) in the shells, and hence the spectral energy distributions (SEDs) of the molecular and atomic line emission from these swept-up shells and the associated parent giant molecular clouds (GMCs) contains a signature of the stage of evolution of the starburst. The physical and chemical properties of the shells and their structure are computed using a a simple well known similarity solution for the shell expansion, a stellar population synthesis...

  15. Method of evaluating chemical shifts of X-ray emission lines in molecules and solids

    OpenAIRE

    Lomachuk, Yuriy V.; Titov, Anatoly V.

    2013-01-01

    Method of evaluating chemical shifts of X-ray emission lines for sufficiently heavy atoms (beginning from period 4 elements) in chemical compounds is developed. This method is based on the pseudopotential model and one-center restoration method (to reconstruct the proper electronic structure in heavy-atom cores). The approximations of instantaneous transition and frozen inner core spinors of the atom are used for derivation of an expression for chemical shift as a difference between mean valu...

  16. Laboratory Measurements of Fe XXIV Line Emission: 3->2 Transitions near Excitation Threshold

    Science.gov (United States)

    Gu, M. F.; Kahn, S. M.; Savin, D. W.; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Reed, K. J.; Bhalla, C. P.; Grabbe, S. R.

    1999-04-01

    Using the Electron Beam Ion Trap facility at Lawrence Livermore National Laboratory, we have measured relative cross sections for Fe XXIV line emission at electron energies between 0.7 and 3.0 keV. The measurements include line formation by direct electron-impact excitation (DE), radiative cascades, resonant excitation (RE), and dielectronic recombination (DR) satellites with captured electron in n>=5 levels. Good agreement with R-matrix and distorted wave calculations is found. In collisionally ionized plasmas, at temperatures near where the ion abundance peaks (kTe ~ 1.7 keV), the RE contributions are found to be ≲ 5% of the line emission, while the DR satellites contribute ≲ 10%. While good agreement with state-of-the-art atomic physics calculations is found, there is less good agreement with existing spectral synthesis codes in common astrophysical use. For the Fe XXIV 3p_{3/2}-> 2s_{1/2}, 3d_{3/2}-> 2p_{3/2}, and 3d_{5/2}-> 2p_{3/2} transitions, the synthesis code MEKAL underestimates the emissivity in coronal equilibrium by ~ 20% at temperatures near where the ion abundance peaks. In situations where the ionization balance is not solely determined by the electron temperature, RE and DR satellites may contribute a considerable fraction of the line emission. Work at Lawrence Livermore National Laboratory was performed under the auspices of the US Department of Energy under contract No. W-7405-ENG-48. This program is supported by a NASA High Energy Astrophysics X-Ray Astronomy Research and Analysis grant NAGW-4185 (Columbia University) and work order W-19127 (LLNL). The work at Kansas State University is supported by Division of Chemical Science, Office of Basic Energy Research, U.S. Department of Energy.

  17. A Near-Infrared Imaging Study of Seyfert Galaxies with Extended Emission line Regions

    Science.gov (United States)

    Alonso-Herrero, Almudena; Simpson, Chris; Ward, Martin J.; Wilson, Andrew S.

    1997-01-01

    We present a near-infrared J,H,K and L' band (1.25 - 3.80 mue) imaging study of a sample of Seyfert galaxies, including some of the best studied examples of these with extended emission line regions (EELR). The observed near-IR nuclear colors are consistent with mixture of emmisions from an old stellar population and unredening hot dust.

  18. Interpreting broad emission-line variations - II. Tensions between luminosity, characteristic size, and responsivity

    Science.gov (United States)

    Goad, M. R.; Korista, K. T.

    2015-11-01

    We investigate the variability behaviour of the broad H β emission-line to driving continuum variations in the best-studied AGN NGC 5548. For a particular choice of broad emission-line region (BLR) geometry, H β surface emissivity based on photoionization models, and using a scaled version of the 13-yr optical continuum light-curve as a proxy for the driving ionizing continuum, we explore several key factors that determine the broad emission-line luminosity L, characteristic size RRW, and variability amplitude (i.e. responsivity) η, as well as the interplay between them. For fixed boundary models which extend as far as the hot dust the predicted delays for H β are on average too long. However, the predicted variability amplitude of H β provides a remarkably good match to observations except during low-continuum states. We suggest that the continuum flux variations which drive the redistribution in H β surface emissivity F(r) do not on their own lead to large enough changes in RRW or ηeff. We thus investigate dust-bounded BLRs for which the location of the effective outer boundary is modulated by the continuum level and the dust-sublimation and dust-condensation time-scales. We find that in order to match the observed variability amplitude of broad H β in NGC 5548 a rather static outer boundary is preferred. Intriguingly, we show that the most effective way of reducing the H β delay, while preserving its responsivity and equivalent width, is to invoke a smaller value in the incident ionizing photon flux ΦH for a given ionizing source-cloud radial distance r, than is normally inferred from the observed UV continuum flux and typical models of the continuum spectral energy distribution.

  19. Performance of a Line Loss Correction Method for Gas Turbine Emission Measurements

    Science.gov (United States)

    Hagen, D. E.; Whitefield, P. D.; Lobo, P.

    2015-12-01

    International concern for the environmental impact of jet engine exhaust emissions in the atmosphere has led to increased attention on gas turbine engine emission testing. The Society of Automotive Engineers Aircraft Exhaust Emissions Measurement Committee (E-31) has published an Aerospace Information Report (AIR) 6241 detailing the sampling system for the measurement of non-volatile particulate matter from aircraft engines, and is developing an Aerospace Recommended Practice (ARP) for methodology and system specification. The Missouri University of Science and Technology (MST) Center for Excellence for Aerospace Particulate Emissions Reduction Research has led numerous jet engine exhaust sampling campaigns to characterize emissions at different locations in the expanding exhaust plume. Particle loss, due to various mechanisms, occurs in the sampling train that transports the exhaust sample from the engine exit plane to the measurement instruments. To account for the losses, both the size dependent penetration functions and the size distribution of the emitted particles need to be known. However in the proposed ARP, particle number and mass are measured, but size is not. Here we present a methodology to generate number and mass correction factors for line loss, without using direct size measurement. A lognormal size distribution is used to represent the exhaust aerosol at the engine exit plane and is defined by the measured number and mass at the downstream end of the sample train. The performance of this line loss correction is compared to corrections based on direct size measurements using data taken by MST during numerous engine test campaigns. The experimental uncertainty in these correction factors is estimated. Average differences between the line loss correction method and size based corrections are found to be on the order of 10% for number and 2.5% for mass.

  20. M-shell satellite structure of 74W x-ray emission lines

    International Nuclear Information System (INIS)

    The spectra of the x-ray emission lines have a complex structure due to the presence of additional holes in the outer shell, which accompany the main transition. The additional holes are called spectator holes, and the induced transitions which are slightly shifted, usually on the higher energy side of the diagram line, are called satellite lines. Although the origin of these satellite lines can been explained by various mechanisms, there are few experimental studies which actually consider the presence of the satellite lines in the spectra on a theoretical ground. Compared to L-shell x-ray emission spectra, the spectra of M-shell x-ray spectra have a far more complicated structure, as the spectator holes can be created by an increased number of channels, such as shake-off, Auger, Coster-Kronig and super-Coster-Kronig transitions. In the present work we attempt to identify the contribution of the Coster-Kronig induced satellites in the M-shell spectra of 74W, both experimentally and theoretically. The 74W Mα,β emission lines generated by electron bombardment from a rotary target x-ray generator were measured by a high resolution single crystal spectrometer, using the (400) plane of a RAP single crystal. The spectra were fitted into Lorentzians; the satellite structure observed on the higher energy side of the corresponding diagram line in a energy range of 2-18 eV, is compared with the experimental results obtained by Munier. In order to identify the transition of the satellites, the transition energy was calculated by means of relativistic density-functional calculations for the case of single spectator holes which can accompany the diagram transition by subsequent Coster-Kronig transitions. The Coster-Kronig induced satellites have been found to be very close to their parent line (0.7 - 4.4 eV). The higher energy satellite structure which goes up to 18 eV apart from the parent line is considered to be due to M-shell spectator holes which can be created mainly

  1. Empirically Constrained Predictions for Metal-Line Emission from the Circumgalactic Medium

    CERN Document Server

    Corlies, Lauren

    2016-01-01

    The circumgalactic medium (CGM) remains one of the least constrained components of galaxies and as such has significant potential for advancing galaxy formation theories. In this work, we vary the extragalactic ultraviolet background for a high-resolution cosmological simulation of a Milky Way-like galaxy and examine the effect on the absorption and emission properties of metals in the CGM. We find that a reduced quasar background brings the column density predictions into better agreement with recent data. Similarly, when the observationally derived physical properties of the gas are compared to the simulation, we find that the simulation gas is always at temperatures approximately 0.5 dex higher. Thus, similar column densities can be produced from fundamentally different gas. However, emission maps can provide complementary information to the line-of-sight column densities to better derive gas properties. From the simulations, we find that the brightest emission is less sensitive to the extragalactic backgr...

  2. Emission line taxonomy and the nature of AGN-looking galaxies in the SDSS

    CERN Document Server

    Fernandes, Roberto Cid; Asari, Natalia Vale; Mateus, Abilio; Schlickmann, Marielli; Schoenell, William

    2009-01-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separately because one cannot fully classify them onto the standard Star-Forming, Seyfert of LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to expl...

  3. Spectroscopic Study of the HST/ACS PEARS Emission-Line Galaxies

    CERN Document Server

    Xia, Lifang; Rhoads, James; Pirzkal, Norbert; Meurer, Gerhardt; Straughn, Amber; Floyd, David; Zheng, Zhenya

    2010-01-01

    We present spectroscopy of 76 emission-line galaxies (ELGs) in CDF-S taken with the LDSS3 spectrograph on Magellan Telescope. These galaxies are selected to have emission lines with ACS grism data in the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) grism Survey. While the ACS grism spectra cover the wavelength range 6000-9700 {\\AA} and most PEARS grism redshifts are based on a single emission line + photometric redshifts from broad-band colors; the Magellan spectra cover a wavelength range of 4000 {\\AA} to 9000 {\\AA}, and provide a check on redshifts derived from PEARS data. We find an accuracy of {\\sigma}z = 0.006 for the grism redshifts with only one catastrophic outlier. For 14 galaxies at z 10$^{43} ergs s$^{-1}, and power-law continuum spectra. Three objects are identified as starburst galaxies from the full-band X-ray luminosity L$_{FB} ~ 10$^{41}$ ergs s$^{-1}.

  4. Hard X-ray emission and $^{44}$Ti line features of Tycho Supernova Remnant

    CERN Document Server

    Wang, Wei

    2014-01-01

    A deep hard X-ray survey of the INTEGRAL satellite first detected the non-thermal emission up to 90 keV in the Tycho supernova (SN) remnant. Its 3 -- 100 keV spectrum is fitted with a thermal bremsstrahlung of $kT\\sim 0.81\\pm 0.45$ keV plus a power-law model of $\\Gamma \\sim 3.01\\pm 0.16$. Based on the diffusive shock acceleration theory, this non-thermal emission, together with radio measurements, implies that Tycho remnant may not accelerate protons up to $>$PeV but hundreds TeV. Only heavier nuclei may be accelerated to the cosmic ray spectral "knee". In addition, we search for soft gamma-ray lines at 67.9 and 78.4 keV coming from the decay of radioactive $^{44}$Ti in Tycho remnant by INTEGRAL. A bump feature in the 60-90 keV energy band, potentially associated with the $^{44}$Ti line emission, is found with a marginal significance level of $\\sim$ 2.6 $\\sigma$. The corresponding 3 $\\sigma$ upper limit on the $^{44}$Ti line flux amounts to 1.5 $\\times$ 10$^{-5}$ ph cm$^{-2}$ s$^{-1}$. Implications on the pro...

  5. The optical emission lines of type 1 X-ray bright Active Galactic Nuclei

    CERN Document Server

    La Mura, G; Ciroi, S; Cracco, V; Di Mille, F; Rafanelli, P

    2013-01-01

    A strong X-ray emission is one of the defining signatures of nuclear activity in galaxies. According to the Unified Model for Active Galactic Nuclei (AGN), both the X-ray radiation and the prominent broad emission lines, characterizing the optical and UV spectra of Type 1 AGNs, are originated in the innermost regions of the sources, close to the Super Massive Black Holes (SMBH), which power the central engine. Since the emission is concentrated in a very compact region (with typical size $r 2000 km/s) and narrow line (1000 km/s < FWHMH$_{\\rm H\\beta}\\, \\leq$ 2000 km/s) emitting objects, it has been observed that the kinematic and ionization properties of matter close to the SMBHs are related together, and, in particular, that ionization is higher in narrow line sources. Here we report on the study of the optical and X-ray spectra of a sample of Type 1 AGNs, selected from the Sloan Digital Sky Survey (SDSS) database, within an upper redshift limit of z = 0.35, and detected at X-ray energies. We present anal...

  6. Photometry of the 4686 A emission line of gamma(2) Velorum from the South Pole

    International Nuclear Information System (INIS)

    An automated optical telescope located at the Amundsen-Scott South Pole station on Antarctica, has been used to obtain more than 78 h of photometry of the He II emission line (4686 A) of the spectroscopic binary gamma(2) Velorum. These data were obtained on seven different days during the 1987 austral winter; the longest continuous run spans 19 h. Two independent period search techniques have been used to search for periodic behavior in the strength of the He II emission line of this Wolf-Rayet star. They are: (1) power spectrum analysis and (2) a first-order sine function fit to the data using least squares. Various multiplicities of a period on the order of 1.3 h with amplitudes of a few percent are found in most of these data. According to recent theoretical models of Wolf-Rayet stars, fluctuations in the He II emission line may indicate vibrational instability in gamma(2) Vel. These pulsations may, in turn, give rise to shocks which propagate outward and which may provide the necessary conditions for periodic changes in the state of a given region of the atmosphere to occur. 15 refs

  7. Fe Line Diagnostics of Cataclysmic Variables and Galactic Ridge X-ray Emission

    CERN Document Server

    Xu, Xiao-jie; Li, Xiang-Dong

    2016-01-01

    The properties of the Galactic Ridge X-ray Emission (GRXE) observed in the 2-10 keV band place fundamental constraints on various types of X-ray sources in the Milky Way. Although the primarily discrete origin of the emission is now well established, the responsible populations of these sources remain uncertain, especially at relatively low fluxes. To provide insights into this issue, we systematically characterize the Fe emission line properties of the candidate types of the sources in the solar neighborhood and compare them with those measured for the GRXE. Our source sample includes 6 symbiotic stars (SSs), 16 intermediate polars (IPs), 3 polars, 16 quiescent dwarf novae (DNe) and 4 active binaries (ABs). We find that the mean equivalent width ($EW_{6.7}$) of the 6.7-keV line and the mean 7.0/6.7-keV line ratio are $107\\pm16.0$ eV and $0.71\\pm 0.04$ for intermediate polars and $221\\pm 135$ eV and $0.44\\pm 0.14$ for polars, respectively, which are all substantially different from those ($490\\pm15 $~eV and $...

  8. Interpreting broad emission-line variations II: Tensions between luminosity, characteristic size and responsivity

    CERN Document Server

    Goad, Michael R

    2015-01-01

    We investigate the variability behaviour of the broad Hb emission-line to driving continuum variations in the best-studied AGN NGC 5548. For a particular choice of BLR geometry, Hb surface emissivity based on photoionization models, and using a scaled version of the 13 yr optical continuum light curve as a proxy for the driving ionizing continuum, we explore several key factors that determine the broad emission line luminosity L, characteristic size R(RW), and variability amplitude (i.e., responsivity) eta, as well as the interplay between them. For fixed boundary models which extend as far as the hot-dust the predicted delays for Hb are on average too long. However, the predicted variability amplitude of Hb provides a remarkably good match to observations except during low continuum states. We suggest that the continuum flux variations which drive the redistribution in Hb surface emissivity F(r) do not on their own lead to large enough changes in R(RW) or eta(eff). We thus investigate dust-bounded BLRs for w...

  9. ALMA Imaging of the CO(6-5) Line Emission in NGC 7130

    CERN Document Server

    Zhao, Yinghe; Xu, Kevin C; Gao, Yu; Barcos-Munoz, Loreto; Diaz-Santos, Tanio; Appleton, Philip; Charmandaris, Vassilis; Armus, Lee; van der Werf, Paul; Evans, Aaron; Cao, Chen; Inami, Hanae; Murphy, Eric

    2016-01-01

    In this paper, we report our high-resolution ($0^{\\prime\\prime}.20\\times0^{\\prime\\prime}.14$ or $\\sim$$70\\times49$ pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 $\\mu$m dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are $1230\\pm74$ Jy km s$^{-1}$ and $814\\pm52$ mJy, respectively, which account for 100% and 51% of their total respective fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of $\\sim$70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an Active Galactic Nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of t...

  10. Restarting radio activity and dust emission in radio-loud broad absorption line quasars

    CERN Document Server

    Bruni, G; Montenegro-Montes, F M; Brienza, M; González-Serrano, J I

    2015-01-01

    Broad absorption line quasars (BAL QSOs) are objects showing absorption from relativistic outflows, with velocities up to 0.2c. These manifest, in about 15% of quasars, as absorption troughs on the blue side of UV emission lines, such as C iv and Mg ii. In this work, we complement the information collected in the cm band for our previously presented sample of radio loud BAL QSOs with new observations at m and mm bands. Our aim is to verify the presence of old, extended radio components in the MHz range, and probe the emission of dust (linked to star formation) in the mm domain. We observed 5 sources from our sample, already presenting hints of low-frequency emission, with the GMRT at 235 and 610 MHz. Other 17 sources (more than half the sample) were observed with bolometer cameras at IRAM-30m and APEX. All sources observed with the GMRT present extended emission at a scale of tens of kpc. In some cases these measurements allow us to identify a second component in the SED, at frequencies below 1.4 GHz, beyond ...

  11. Estimating Black Hole Masses of AGNs using Ultraviolet Emission Line Properties

    Institute of Scientific and Technical Information of China (English)

    Min-Zhi Kong; Xue-Bing Wu; Ran Wang; Jin-Lin Han

    2006-01-01

    Based on measured broad line region sizes in the reverberation-mapping AGN sample, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift (z > 0.5) AGNs. First, using the archival IUE/HST spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical relations between the BLR size and Mg Ⅱ/C Ⅳ emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mapping sample as calibration, we found two new relationships for determining the black hole mass with the full width at half maximum and the luminosity of Mg Ⅱ/C Ⅳ line. We then apply the relations to estimate the black hole masses of the AGNs in the Large Bright Quasar Survey and a sample of radio-loud quasars. For the objects with small radio-loudness, the black hole mass estimated using the RBLR-LMg Ⅱ/C Ⅳ relation is consistent with that from the RBLR-L3000(A)/1350(A) relation. For radio-loud AGNs, however, the mass estimated from the RBLR-LMg Ⅱ/C Ⅳ relation is systematically lower than that from the continuum luminosity L3000 (A)/1350 (A).Because jets could have significant contributions to the UV/optical continuum luminosity of radio-loud AGNs,we emphasize once again that for radio-loud AGNs, the emission line luminosity may be a better tracer of the ionizing luminosity than the continuum luminosity, so that the relations between the BLR size and UV emission line luminosities should be used to estimate the black hole masses of high redshift radio-loud AGNs.

  12. The SAURON project - V. Integral-field emission-line kinematics of 48 elliptical and lenticular galaxies

    CERN Document Server

    Sarzi, M; Davies, R L; Bacon, R; Bureau, M; Cappellari, M; De Zeeuw, P T; Emsellem, E; Fathi, K; Krajnovic, D; Kuntschner, H; McDermid, R M; Peletier, R F; Emsellem, Eric; Peletier, Reynier F.

    2006-01-01

    We present the emission-line fluxes and kinematics of 48 representative elliptical and lenticular galaxies obtained with our custom-built integral-field spectrograph SAURON. Hb, [OIII], and [NI] emission lines were measured using a new procedure that simultaneously fits both the stellar spectrum and the emission lines. Using this technique we can detect emission lines down to an equivalent width of 0.1A set by the current limitations in describing galaxy spectra with synthetic and real stellar templates, rather than by the quality of our spectra. Emission is detected in 75% of our sample galaxies, and comes in a variety of resolved spatial distributions and kinematic behaviours. The ionised-gas kinematics is rarely consistent with simple coplanar circular motions. However, the gas almost never displays completely irregular kinematics, generally showing coherent motions with smooth variations in angular momentum. In the majority of the cases the gas kinematics is decoupled from the stellar kinematics, and in h...

  13. Broad Hbeta Emission-Line Variability in a Sample of 102 Local Active Galaxies

    CERN Document Server

    Runco, Jordan N; Bennert, Vardha N; Scott, Bryan; Komossa, S; Malkan, Matthew A; Lazarova, Mariana S; Auger, Matthew W; Treu, Tommaso; Park, Daeseong

    2016-01-01

    A sample of 102 local (0.02 10^7 M_sun was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10-m telescope to study the scaling relations between MBH and host galaxy properties. We study profile changes of the broad Hbeta emission line within the ~3-9 year time-frame between the two sets of spectra. The variability of the broad Hbeta emission line is of particular interest, not only since it is used to estimate MBH, but also since its strength and width is used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (~66%) of the objects, resulting in a Seyfert-type change for ~38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hbeta line virtually disappears in 3/102 (~3%) extreme cases. We discuss potential causes for these changing-look AGNs. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case ...

  14. First Detection of Ar-K Line Emission from the Cygnus Loop

    CERN Document Server

    Uchida, H; Tominaga, N; Katsuda, S; Kimura, M; Kosugi, H; Takahashi, H; Takakura, S

    2011-01-01

    We observed the Cygnus Loop with XMM-Newton (9 pointings) and Suzaku (32 pointings) between 2002 and 2008. The total effective exposure time is 670.2 ks. By using all of the available data, we intended to improve a signal-to-noise ratio of the spectrum. Accordingly, the accumulated spectra obtained by the XIS and the EPIC show some line features around 3 keV that are attributed to the S He$\\beta$ and Ar He$\\alpha$ lines, respectively. Since the Cygnus Loop is an evolved ($\\sim$10,000 yr) supernova remnant whose temperature is relatively low ($<$1 keV) compared with other young remnants, its spectrum is generally faint above 3.0 keV, no emission lines, such as the Ar-K line have ever been detected. The detection of the Ar-K line is the first time and we found that its abundance is significantly higher than that of the solar value; 9.0$^{+4.0}_{-3.8}$ and 8.4$^{+2.5}_{-2.7}$ (in units of solar), estimated from the XIS and the EPIC spectra, respectively. We conclude that the Ar-K line originated from the ejec...

  15. Neon and [CII] 158 micron Emission Line Profiles in Dusty Starbursts and Active Galactic Nuclei

    CERN Document Server

    Samsonyan, Anahit; Lebouteiller, Vianney; Barry, Donald; Sargsyan, Lusine

    2016-01-01

    The sample of 379 extragalactic sources is presented that have mid-infrared, high resolution spectroscopy with the Spitzer Infrared Spectrograph (IRS) and also spectroscopy of the [CII] 158 um line with the Herschel Photodetector Array Camera and Spectrometer (PACS). The emission line profiles of [NeII] 12.81 um, [NeIII] 15.55 um, and [CII] 158 um are presented, and intrinsic line widths are determined (full width half maximum of Gaussian profiles after instrumental correction). All line profiles together with overlays comparing positions of PACS and IRS observations are made available in the Cornell Atlas of Spitzer IRS Sources (CASSIS). Sources are classified from AGN to starburst based on equivalent widths of the 6.2 um polycyclic aromatic hydrocarbon feature. It is found that intrinsic line widths do not change among classification for [CII], with median widths of 207 km per s for AGN, 248 km per s for composites, and 233 km per s for starbursts. The [NeII] line widths also do not change with classificati...

  16. EDDINGTON RATIO GOVERNS THE EQUIVALENT WIDTH OF Mg II EMISSION LINE IN ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    We have investigated the ensemble regularities of the equivalent widths (EWs) of Mg II λ2800 emission line of active galactic nuclei (AGNs), using a uniformly selected sample of 2092 Seyfert 1 galaxies and quasars at 0.45 ≤ z ≤ 0.8 in the spectroscopic data set of the Sloan Digital Sky Survey Fourth Data Release. We find a strong correlation between the EW of Mg II and the AGN Eddington ratio (L/LEdd): EW(Mg II) ∝ (L/L Edd)-0.4. Furthermore, for AGNs with the same L/LEdd, their EWs of Mg II show no correlation with luminosity, black hole mass, or line width, and the Mg II line luminosity is proportional to continuum luminosity, as expected by photoionization theory. Our result shows that Mg II EW is not dependent on luminosity, but is solely governed by L/LEdd.

  17. Intensity enhancement of O VI ultraviolet emission lines in solar spectra due to opacity

    CERN Document Server

    Keenan, F P; Madjarska, M S; Rose, S J; Bowler, L A; Britton, J; McCrink, L; Mathioudakis, M

    2014-01-01

    Opacity is a property of many plasmas, and it is normally expected that if an emission line in a plasma becomes optically thick, its intensity ratio to that of another transition that remains optically thin should decrease. However, radiative transfer calculations undertaken both by ourselves and others predict that under certain conditions the intensity ratio of an optically thick to thin line can show an increase over the optically thin value, indicating an enhancement in the former. These conditions include the geometry of the emitting plasma and its orientation to the observer. A similar effect can take place between lines of differing optical depth. Previous observational studies have focused on stellar point sources, and here we investigate the spatially-resolved solar atmosphere using measurements of the I(1032 A)/I(1038 A) intensity ratio of O VI in several regions obtained with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument on board the Solar and Heliospheric Observatory (...

  18. Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.

    2016-06-01

    Aims: We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods: We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results: We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These "shells" are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey (program 188.B-3002).Full Tables 1-3 are only available at the CDS via anonymous ftp to http

  19. THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A.; Treu, Tommaso [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Pancoast, Anna [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sand, David J. [Texas Tech University, Physics Department, Box 41051, Lubbock, TX 79409-1051 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Assef, Roberto J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Brewer, Brendon J. [Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, MC 661, Greenbelt, MD 20771 (United States); and others

    2015-04-15

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  20. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-line Light Curves

    Science.gov (United States)

    Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E..; Li, Weidong; Malkan, Matthew A.; Pancoast, Anna; Sand, David J.; Stern, Daniel; Cenko, S. Bradley

    2016-01-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hß line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad H beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H beta velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad H beta velocity shifted by approximately 250 km s(exp -1) over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  1. Model for Atomic Oxygen Visible Line Emissions in Comet C/1995 O1 Hale-Bopp

    CERN Document Server

    Raghuram, Susarla

    2012-01-01

    We have recently developed a coupled chemistry-emission model for the green and red-doublet emissions of atomic oxygen on comet Hyakutake. In the present work we applied our model to comet Hale-Bopp, which had an order of magnitude higher H2O production rate than comet Hyakutake, to evaluate the photochemistry associated with the production and loss of O(1S) and O(1D) atoms and emission processes of green and red-doublet lines. We present the wavelength-dependent photo-attenuation rates for different photodissociation processes forming O(1S) and O(1D). The calculated radiative efficiency profiles of O(1S) and O(1D) atoms show that in comet Hale-Bopp the green and red-doublet emissions are emitted mostly above radial distances of 10^3 and 10^4 km, respectively. The model calculated [OI] 6300 A emission surface brightness and average intensity over the Fabry-P{\\'e}rot spectrometer field of view are consistent with the observation of Morgenthaler et al. (2001), while the intensity ratio of green to red-doublet e...

  2. Empirically Constrained Predictions for Metal-line Emission from the Circumgalactic Medium

    Science.gov (United States)

    Corlies, Lauren; Schiminovich, David

    2016-08-01

    The circumgalactic medium (CGM) is one of the remaining least constrained components of galaxies and as such has significant potential for advancing galaxy formation theories. In this work, we vary the extragalactic ultraviolet background for a high-resolution cosmological simulation of a Milky-Way-like galaxy and examine the effect on the absorption and emission properties of metals in the CGM. We find that a reduced quasar background brings the column density predictions into better agreement with recent data. Similarly, when the observationally derived physical properties of the gas are compared to the simulation, we find that the simulation gas is always at temperatures approximately 0.5 dex higher. Thus, similar column densities can be produced from fundamentally different gas. However, emission maps can provide complementary information to the line-of-sight column densities to better derive gas properties. From the simulations, we find that the brightest emission is less sensitive to the extragalactic background and that it closely follows the fundamental filamentary structure of the halo. This becomes increasingly true as the galaxy evolves from z = 1 to z = 0 and the majority of the gas transitions to a hotter, more diffuse phase. For the brightest ions (C iii, C iv, O vi), detectable emission can extend as far as 120 kpc at z = 0. Finally, resolution is a limiting factor for the conclusions we can draw from emission observations, but with moderate resolution and reasonable detection limits, upcoming instrumentation should place constraints on the physical properties of the CGM.

  3. Checking Potassium origin of new emission line at 3.5 keV with K XIX line complex at 3.7 keV

    CERN Document Server

    Iakubovskyi, Dmytro

    2015-01-01

    Whether the new line at ~3.5 keV, recently detected in different samples of galaxy clusters, Andromeda galaxy and central part of our Galaxy, is due to Potassium emission lines, is now unclear. By using the latest astrophysical atomic emission line database AtomDB v. 3.0.2, we show that the most prospective method to directly check its Potassium origin will be the study of K XIX emission line complex at ~3.7 keV with future X-ray imaging spectrometers such as Soft X-ray spectometer on-board Astro-H mission or microcalorimeter on-board Micro-X sounding rocket experiment. To further reduce the remaining (factor ~3-5) uncertainty of the 3.7/3.5 keV ratio one should perform more precise modeling including removal of significant spatial inhomogeneities, detailed treatment of background components, and further extension of the modeled energy range.

  4. Effects of excitation laser wavelength on Ly-α and He-α line emission from nitrogen plasmas

    OpenAIRE

    Harilal, S. S.; Miloshevsky, G. V.; Sizyuk, T.; Hassanein, A.

    2013-01-01

    Laser-produced nitrogen plasmas emitting radiation at 2.48 nm (Ly-α) and 2.88 nm (He-α) are considered potential efficient sources for water-window (WW) microscopy. The atomic and optical properties of nitrogen plasma and influence of the laser wavelength on the line emission in the WW range are investigated. It is found that the optimal temperatures for maximum emission from Ly-α and He-α spectral lines are 40-60 eV and 80-100 eV, respectively. The WW line emission and the conversion efficie...

  5. Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments

    CERN Document Server

    Sankrit, Ravi; Blair, William P; Long, Knox S; Williams, Brian J; Borkowski, Kazimierz J; Patnaude, Daniel J; Reynolds, Stephen P

    2015-01-01

    We report on the proper motions of Balmer-dominated filaments in Kepler's supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of 5.1 [+0.8, -0.7] kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km/s and is encountering material with densities of about 8 cm^-3. We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations amon...

  6. High resolution imaging of molecular line emission from high redshift QSOs

    CERN Document Server

    Carilli, C L; Kawabe, R; Ohta, K; Henkel, C; Menten, K M; Yun, M; Petric, A; Tutui, Y

    2002-01-01

    We present moderate (1'') and high resolution (0.2'') observations of the CO(2-1) emission at 43 GHz, and radio continuum emission at 1.47 GHz, from the z=4.7 QSO BRI 1202-0725 and the z=4.4 QSO BRI 1335--0417 using the Very Large Array. The moderate resolution observations show that in both cases the CO emission is spatially resolved into two components separated by 1'' for 1335-0417 and 4'' for 1202-0725. The high resolution observations show that each component has sub-structure on scales of 0.2'' to 0.5'', with intrinsic brightness temperatures > 20K. The CO ladder from (2-1) up to (7-6) suggests a high kinetic temperature for the gas (70 K), and a high column density (10^{24} cm^{-2}). In both sources the continuum-to-line ratio: L_{FIR}/L'_{CO(1-0)} = 335. All these characteristics (brightness temperature, excitation temperature, column density, and continuum-to-line ratio) are comparable to conditions found in low redshift, ultra-luminous nuclear starburst galaxies. We find that the CO emitting regions...

  7. Activity from Magnetar Candidate 4U 0142+61: Bursts and Emission Lines

    CERN Document Server

    Gavriil, Fotis P; Kaspi, Victoria M

    2007-01-01

    After 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months. During the active phase, several bursts were detected, and many aspects of the X-ray emission changed. We report on the discovery of six X-ray bursts, the first ever seen from this AXP in ~10 years of Rossi X-ray Timing Explorer (RXTE) monitoring. All the bursts occurred in the interval between 2006 April 6 and 2007 February 7. The bursts had the canonical fast rise slow decay profiles characteristic of SGR/AXP bursts. The burst durations ranged from 8-3x10^3 s as characterized by T90,these are very long durations even when compared to the broad T90 distributions of other bursts from SGRs and AXPs. The first five burst spectra are well modeled by simple blackbodies, with temperature kT ~2-6 keV. However, the sixth burst had a complicated spectrum consisting of at least three emission lines with possible additional emission and absorption lines. The most significant feature was...

  8. Optimization of InGaN quantum dots for single line emission at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zakizadeh, Elahe; Dartsch, Heiko; Aschenbrenner, Timo; Figge, Stephan; Kruse, Carsten; Hommel, Detlef [Institute of Solid State Physics, University of Bremen (Germany)

    2012-07-01

    Due to the large bandgap and high exciton binding energy of the nitrides, InGaN quantum dots (QDs) are promising candidates for single photon emission at room temperature. In this presentation we show results of micro photoluminescence measurements on InGaN quantum dots formed by a spinodal decomposition process in MOVPE. The samples show quantum dot related photoluminescence in the blue-green spectral region. Simple GaN layers containing InGaN QDs have been investigated as well as a fully monolithically grown cavity structure with InGaN QDs at the antinode position of a cavity between two GaN/AlInN Bragg reflectors. Single line QD emission could be observed up to a temperature of 100 K. In order to achieve single line emission at higher temperatures a novel concept of introducing AlGaN or AlInN barriers for larger carrier confinement will be discussed and first results will be shown.

  9. Sub-mm Emission Line Deep Fields: CO and [CII] Luminosity Functions out to z = 6

    CERN Document Server

    Popping, Gergö; Decarli, Roberto; Spaans, Marco; Somerville, Rachel S; Trager, Scott C

    2016-01-01

    Now that ALMA is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. Deep fields are ideal to study the luminosity function of sub-mm emission lines, ultimately tracing the atomic and molecular gas properties of galaxies. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J=1-0 up to CO J=6-5 and [CII] at redshifts z=0-6. We find that: 1) our model correctly reproduces the CO and [CII] emission of low- and high-redshift galaxies and reproduces the available constraints on the CO luminosity function at z1.5 and the CO luminosity of individual galaxies at intermediate redshifts. We argue that this is driven by a lack of cold gas in galaxies at intermediate redshifts as predicted by cosmological simulations of galaxy formation. This may lay at the root of other problems theoretical models face at the same redshifts.

  10. 2D-photochemical model for forbidden oxygen line emission for comet 1P/Halley

    Science.gov (United States)

    Cessateur, G.; De Keyser, J.; Maggiolo, R.; Rubin, M.; Gronoff, G.; Gibbons, A.; Jehin, E.; Dhooghe, F.; Gunell, H.; Vaeck, N.; Loreau, J.

    2016-08-01

    We present here a 2D-model of photochemistry for computing the production and loss mechanisms of the O(1S) and O(1D) states, which are responsible for the emission lines at 577.7 nm, 630 nm, and 636.4 nm, in case of the comet 1P/Halley. The presence of O2 within cometary atmospheres, measured by the in-situ ROSETTA and GIOTTO missions, necessitates a revision of the usual photochemical models. Indeed, the photodissociation of molecular oxygen also leads to a significant production of oxygen in excited electronic states. In order to correctly model the solar UV flux absorption, we consider here a 2D configuration. While the green to red-doublet ratio is not affected by the solar UV flux absorption, estimates of the red-doublet and green lines emissions are, however, overestimated by a factor of two in the 1D model compared to the 2D model. Considering a spherical symmetry, emission maps can be deduced from the 2D model in order to be directly compared to ground and/or in-situ observations.

  11. SDSS-IV eBOSS emission-line galaxy pilot survey

    Science.gov (United States)

    Comparat, J.; Delubac, T.; Jouvel, S.; Raichoor, A.; Kneib, J.-P.; Yèche, C.; Abdalla, F. B.; Le Cras, C.; Maraston, C.; Wilkinson, D. M.; Zhu, G.; Jullo, E.; Prada, F.; Schlegel, D.; Xu, Z.; Zou, H.; Bautista, J.; Bizyaev, D.; Bolton, A.; Brownstein, J. R.; Dawson, K. S.; Escoffier, S.; Gaulme, P.; Kinemuchi, K.; Malanushenko, E.; Malanushenko, V.; Mariappan, V.; Newman, J. A.; Oravetz, D.; Pan, K.; Percival, W. J.; Prakash, A.; Schneider, D. P.; Simmons, A.; Abbott, T. M. C.; Allam, S.; Banerji, M.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cunha, C. E.; da Costa, L. N.; Desai, S.; Doel, P.; Eifler, T. F.; Estrada, J.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Miquel, R.; Plazas, A. A.; Reil, K.; Roe, N.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, D.; Walker, A. R.; Zhang, Y.

    2016-08-01

    The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195 000 emission-line galaxies (ELGs) to measure the baryonic acoustic oscillation (BAO) standard ruler at redshift 0.9. To test different ELG selection algorithms, 9000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error. Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Finally, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements. The catalog is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A121

  12. Strong field effects on emission line profiles: Kerr black holes and warped accretion disks

    CERN Document Server

    Wang, Yan

    2011-01-01

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, ...

  13. Evaluation of Glucose Uptake in Normal and Cancer Cell Lines by Positron Emission Tomography.

    Science.gov (United States)

    Maddalena, Francesca; Lettini, Giacomo; Gallicchio, Rosj; Sisinni, Lorenza; Simeon, Vittorio; Nardelli, Anna; Venetucci, Angela Assunta; Storto, Giovanni; Landriscina, Matteo

    2015-01-01

    To date, there is no definitive demonstration of the utility of positron emission tomography (PET) in studying glucose metabolism in cultured cell lines. Thus, this study was designed to compare PET to more standardized methods for the quantitative assessment of glucose uptake in nontransformed and transformed living cells and to validate PET for metabolic studies in vitro. Human colon and breast carcinoma cell lines and mouse embryo fibroblasts were evaluated for [(18)F]fluorodeoxyglucose ([(18)F]FDG) uptake by PET and autoradiography and 2-deoxyglucose (2-DG) incorporation by colorimetric assay and analyzed for the radiotoxic effects of [(18)F]FDG and the expression levels of glucose transporters. Indeed, [(18)F]FDG incorporation on PET was comparable to [(18)F]FDG uptake by autoradiography and 2-DG incorporation by colorimetric assay, although radiotracer-based methods exhibited more pronounced differences between individual cell lines. As expected, these data correlated with glucose transporters 1 to 4 and hexokinase II expression in tumor cell lines and mouse fibroblasts. Notably, [(18)F]FDG incorporation resulted in low apoptotic rates, with fibroblasts being slightly more sensitive to radiotracer-induced cell death. The quantitative analysis of [(18)F]FDG uptake in living cells by PET represents a valuable and reproducible method to study tumor cell metabolism in vitro, being representative of the differences in the molecular profile of normal and tumor cell lines.

  14. Optical Emission Lines from Warm Interstellar Clouds a Decisive Test of the Decaying Neutrino Theory

    CERN Document Server

    Sciama, Dennis William

    1998-01-01

    Recently developed instruments such as the Taurus Tunable Filter and WHAM should be able to detect some or all of the optical emission lines H$\\alpha$, [OI] $\\lambda$6300, [SII] $\\lambda$6717, [NI] $\\lambda$ 5200 and [NII] $&$ Fitzpatrick (1993) (SF) along the line of sight to the halo star HD93521. The strengths of these lines should resolve the debate as to whether the free electrons, which SF held responsible for the observed excitation of CII in the clouds, are located mainly in the skins of the clouds or in their interiors. If the free electrons are indeed mainly located in the cloud interiors, then the substantial electron density derived by SF, and its constancy from cloud to cloud for the slow-moving clouds, when combined with their opacity to Lyman continuum radiation, lend strong support to the decaying neutrino theory for the ionisation of the interstellar medium (Sciama 1990, 1993 a, b, 1997). If the [OI] and [NI] lines are relatively strong but the [NII] line is weak, then this would lend fur...

  15. Coexistence of Gravitationally Bound and Radiation Driven CIV Emission Line Regions in Active Galactic Nuclei

    CERN Document Server

    Wang, Huiyuan; Zhou, Hongyan; Liu, Bo; Wang, Jianguo; Yuan, Weimin; Dong, Xiaobo

    2011-01-01

    There are mutually contradictory views in the literature of the kinematics and structure of high-ionization line (e.g. CIV) emitting regions in active galactic nuclei (AGNs). Two kinds of broad emission line region (BELR) models have been proposed, outflow and gravitationally bound BELR, which are supported respectively by blueshift of the CIV line and reverberation mapping observations. To reconcile these two apparently different models, we present a detailed comparison study between the CIV and MgII lines using a sample of AGNs selected from the Sloan Digital Sky Survey. We find that the kinematics of the CIV region is different from that of MgII, which is thought to be controlled by gravity. A strong correlation is found between the blueshift and asymmetry of the CIV profile and the Eddington ratio. This provides strong observational support for the postulation that the outflow is driven by radiation pressure. In particular, we find robust evidence that the CIV line region is largely dominated by outflow a...

  16. Radiative emission of solar features in the Ca II K line: comparison of measurements and models

    CERN Document Server

    Ermolli, I; Uitenbroek, H; Giorgi, F; Rast, M P; Solanki, S K

    2010-01-01

    We study the radiative emission of various types of solar features, such as quiet Sun, enhanced network, plage, and bright plage regions, identified on filtergrams taken in the Ca II K line. We analysed fulldisk images obtained with the PSPT, by using three interference filters that sample the Ca II K line with different bandpasses. We studied the dependence of the radiative emission of disk features on the filter bandpass. We also performed a NLTE spectral synthesis of the Ca II K line integrated over the bandpass of PSPT filters. The synthesis was carried out by utilizing both the PRD and CRD with the most recent set of semi­empirical atmosphere models in the literature and some earlier atmosphere models. We measured the CLV of intensity values for various solar features identified on PSPT images and compared the results obtained with those derived from the synthesis. We find that CRD calculations derived using the most recent quiet Sun model, on average, reproduce the measured values of the quiet Sun regi...

  17. First detection of rotational CO line emission in an RGB star

    CERN Document Server

    Groenewegen, M A T

    2014-01-01

    Context: For stars with initial masses below about 1 solar mass, the mass loss during the first red giant branch (RGB) phase dominates mass loss in the later asymptotic giant branch (AGB) phase. Nevertheless, mass loss on the RGB is still often parameterised by a simple Reimers law in stellar evolution models. Aims: To try to detect CO thermal emission in a small sample of nearby RGB stars with reliable Hipparcos parallaxes that were shown to have infrared excess in an earlier paper. Methods: A sample of five stars was observed in the CO J=2-1 and J=3-2 lines with the IRAM and APEX telescopes. Results: One star, the one with the largest mass-loss rate based on the previous analysis of the spectral energy distribution, was detected. The expansion velocity is unexpectedly large at 12 km/s. The line profile and intensity are compared to the predictions from a molecular line emission code. The standard model predicts a double-peaked profile, while the observations indicate a flatter profile. A model that does fit...

  18. The Binary Black Hole Model for Mrk 231 Cannot Explain the Observed Emission Lines

    CERN Document Server

    Leighly, Karen M; Gallagher, Sarah C; Lucy, Adrian B

    2016-01-01

    Mrk 231 is a nearby quasar with an unusually red continuum, generally explained as heavy reddening by dust (e.g., Leighly et al. 2014). Yan et al. 2015 proposed that Mrk 231 is a milli-parsec black-hole binary with little intrinsic reddening. The large-mass black hole experiences advection-dominated accretion, emitting little continuum, while the accretion disk of the small-mass black hole emits as an ordinary quasar, dominating the observed weak UV continuum and contributing all of the photoionizing flux. We demonstrate that this model is untenable for four reasons. (1) To produce the observed near-infrared emission lines, the equivalent widths would have to be ~100 times larger than typical values with respect to the photoionizing continuum, a situation that seems energetically unlikely. (2) We use the photoionization code Cloudy to demonstrate it is not possible to produce the HeI* emission line intensity for the observed HeI*/Pbeta flux ratios, even if the line-emitting gas intersects all of the photoioni...

  19. Emission Lines from the Gas Disk around TW Hydra and the Origin of the Inner Hole

    CERN Document Server

    Gorti, Uma; Najita, Joan; Pascucci, Ilaria

    2011-01-01

    We compare line emission calculated from theoretical disk models with optical to sub-millimeter wavelength observational data of the gas disk surrounding TW Hya and infer the spatial distribution of mass in the gas disk. The model disk that best matches observations has a gas mass ranging from $\\sim10^{-4}-10^{-5}$\\ms\\ for $0.06{\\rm AU} 13.6$eV) flux from TW Hya. H$_2$ pure rotational line emission comes primarily from $r\\sim 1-30$AU. [OI]63$\\mu$m, HCO$^+$ and CO pure rotational lines all arise from the outer disk at $r\\sim30-120$AU. We discuss planet formation and photoevaporation as causes for the decrease in surface density of gas and dust inside 4 AU. If a planet is present, our results suggest a planet mass $\\sim 4-7$M$_J$ situated at $\\sim 3$AU. Using our photoevaporation models and the best surface density profile match to observations, we estimate a current photoevaporative mass loss rate of $4\\times10^{-9}$\\ms\\ yr$^{-1}$ and a remaining disk lifetime of $\\sim 5$ million years.

  20. Hubble Space Telescope Spectroscopy of the Balmer lines in Sirius B

    OpenAIRE

    Barstow, M. A.; Bond, Howard E.; Holberg, J. B.; Burleigh, M. R.; Hubeny, I.; Koester, D.

    2005-01-01

    Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from space we can take advantage of the superb spatial resolution of the Hubble Space Telescope to resolve the A and B components. Since the closest approach in 1993, the separation between the two stars has become increasingly favourable and we have recently been able to obtain a spectrum of the comp...

  1. Measurements of neutral density profiles using a deuterium Balmer-alpha diagnostic in the C-2 FRC plasma

    International Nuclear Information System (INIS)

    In C-2 field-reversed configuration (FRC) device, low neutral density outside the FRC separatrix is required to minimize the charge exchange loss of fast particles. Titanium gettering is used in C-2 to reduce the wall recycling and keep the neutral density low in plasma edge. The measurements of neutral density radial profile are desirable to understand the plasma recycling and the effects of titanium gettering. These measurements are also needed to study the interaction of neutral beams with FRC plasma and confinement of fast ions. Diagnostic based on absolute deuterium Balmer-alpha (D-alpha) radiation measurements is developed and deployed on C-2 device to measure the radial profile of neutral density. Simultaneous measurements of electron density and temperature are done using CO2 interferometer, Thomson scattering, and triple probes diagnostics along with absolute D-alpha radiation. Abel inversion was performed to get the time dependent radial profile of the local D-alpha emission density. Neutral density profiles are obtained under different machine conditions of titanium deposition.

  2. Investigations on burning efficiency and exhaust emission of in-line type emulsified fuel system

    Directory of Open Access Journals (Sweden)

    Yen Kuei Tseng, Hsien Chang Cheng

    2011-07-01

    Full Text Available In this research, the burning efficiency as well as exhaust emission of a new water-in-oil emulsified fuel system was studied. This emulsified system contains two core processes, the first one is to mix 97% water with 3% emulsifier by volume, and get the milk-like emulsified liquid, while the second one is to compound the milk-like emulsified liquid with heavy oil then obtain the emulsified fuel. In order to overcome the used demulsification problem during in reserve or in transport, this system was designed as a made and use in-line type. From the results of a series burning tests, the fuel saving can be over 8~15%. Also, from the comparison of decline for the heat value and total energy output of varies emulsified fuel, one can find that the water as the dispersed phase in the combustion process will leading a micro-explosion as well as the water gas effect, both can raise the combustion temperature and burning efficiency. By comparing the waste gas emission of different types of emulsified fuel, one can know that, the CO2 emission reduces approximately 14%, and NOx emission reduces above 46%, that means the reduction of the exhaust gas is truly effectively. From the exhaust temperature of tail pipe, the waste heat discharge also may reduce 27%, it is quite advantageous to the global warming as well as earth environmental protection.

  3. Radio continuum detection in blue early-type weak emission line galaxies

    CERN Document Server

    Paswan, A

    2016-01-01

    The star formation rates (SFRs) in weak emission line (WEL) galaxies in a volume-limited ($0.02 < z < 0.05$) sample of blue early-type galaxies (ETGs) identified from SDSS, are constrained here using 1.4 GHz radio continuum emission. The direct detection of 1.4 GHz radio continuum emission is made in 8 WEL galaxies and a median stacking is performed on 57 WEL galaxies using VLA FIRST images. The median stacked 1.4 GHz flux density and luminosity are estimated as 79 $\\pm$ 19 $\\mu$Jy and 0.20 $\\pm$ 0.05 $\\times$ 10$^{21}$ W Hz$^{-1}$ respectively. The radio far-infrared correlation in 4 WEL galaxies suggests that the radio continuum emission from WEL galaxies is most likely due to star formation activities. The median SFR for WEL galaxies is estimated as 0.23 $\\pm$ 0.06 M$_{\\odot}$yr$^{-1}$, which is much less compared to SFRs ($0.5 - 50$ M$_{\\odot}$yr$^{-1}$) in purely star forming blue ETGs. The SFRs in blue ETGs are found to be correlated with their stellar velocity dispersions ($\\sigma$) and decreasin...

  4. P-MaNGA Galaxies: Emission Lines Properties - Gas Ionisation and Chemical Abundances from Prototype Observations

    CERN Document Server

    Belfiore, F; Bundy, K; Thomas, D; Maraston, C; Wilkinson, D; Sánchez, S F; Bershady, M; Blanc, G A; Bothwell, M; Cales, S L; Coccato, L; Drory, N; Emsellem, E; Fu, H; Gelfand, J; Law, D; Masters, K; Parejko, J; Tremonti, C; Wake, D; Weijmans, A; Yan, R; Xiao, T; Zhang, K; Zheng, T; Bizyaev, D; Kinemuchi, K; Oravetz, D; Simmons, A

    2014-01-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a SDSS-IV survey that will obtain spatially resolved spectroscopy from 3600 \\AA\\ to 10300 \\AA\\ for a representative sample of over 10000 nearby galaxies. In this paper we present the analysis of nebular emission line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, illustrating that galaxy characterisations based on single fibre spectra are necessarily incomplete. We observe extended (up to $\\rm 1 R_{e}$) LINER-like emission in the central regions of three galaxies. We make use of the $\\rm EW(H \\alpha)$ to argue that the observed emission is consistent with ionisation from hot evolved stars. Using stellar population indices we conclude that galactic regions which are ionised by a Seyfert/LINER-like radiation field are also devoid of recent st...

  5. Effects of trapped electrons on the line shape in emission Moessbauer spectra

    International Nuclear Information System (INIS)

    To explain line broadening in emission Moessbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom.

  6. Interstellar absorption in the Mg II resonance line k2 and h2 emissions

    Science.gov (United States)

    Boehm-Vitense, E.

    1981-01-01

    High-resolution (0.2 A) IUE spectra for the long wavelength range (1800-3000 A) have been studied. It is shown that narrow interstellar Mg II lines are seen in the center of the k2 and h2 emissions from nearby stars with large rotational velocities. For all observed stars, the radial velocity of the central k3 absorption component in the rest system of the star is strongly correlated with the mirror image of the radial velocity of the stars; this shows that a major fraction if not all of the k3 absorption is due to interstellar absorption in the solar neighborhood. The violet to red asymmetry of the k2 emission also correlates with the radial velocities of the star; this shows that the shift of k3 is due to the velocity shift of the local interstellar cloud with respect to the star.

  7. Instrumentation for continuous on-line monitoring of non-methane organic carbon in air emissions

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, S.; Xu, Y.; Chen, W. [New Jersey Institute of Technology, Newark, NJ (United States); McAllister, G. [Environmental Protection Agency, Durham, NC (United States)

    1996-12-31

    Nonmethane organic carbons (NMOC) is a measure of total organic carbon except that from methane. EPA standard method 25 was developed in the mid 1970`s as a means of quantifying NMOC emission from stationary source such as incinerators and paint industry. This method which involves obtaining a grab sample, and transporting it to the lab for analysis is not suitable for continuous monitoring. Moreover, this GC based method is prone to interferences from moisture and high concentrations of CO{sub 2}. In this paper we discuss the development of a novel columnless instrument that can be used for continuous on-line monitoring of NMOC in emission sources as well as in ambient air. 4 refs., 4 figs.

  8. The Chemical Evolution of Narrow Emission Line Galaxies: the Key to their Formation Processes

    CERN Document Server

    Torres-Papaqui, J P; Ortega-Minakata, R A

    2011-01-01

    Using the largest sample of narrow emission line galaxies available so far, we show that their spectral characteristics are correlated with different physical parameters, like the chemical abundances, the morphologies, the masses of the bulge and the mean stellar age of the stellar populations of the host galaxies. It suggests that the spectral variations observed in standard spectroscopic diagnostic diagrams are not due solely to variations of ionization parameters or structures but reflect also the chemical evolution of the galaxies, which in turn can be explained by different galaxy formation processes.

  9. The Dust Attenuation Curve versus Stellar Mass for Emission Line Galaxies at z ~ 2

    OpenAIRE

    Zeimann, Gregory R.; Ciardullo, Robin; Gronwall, Caryl; Bridge, Joanna; Brooks, Hunter; Fox, Derek; Gawiser, Eric; Gebhardt, Henry; Hagen, Alex; Schneider, Donald P.; Trump, Jonathan R.

    2015-01-01

    We derive the mean wavelength dependence of stellar attenuation in a sample of 239 high redshift (1.90 < z < 2.35) galaxies selected via Hubble Space Telescope (HST) WFC3 IR grism observations of their rest-frame optical emission lines. Our analysis indicates that the average reddening law follows a form similar to that derived by Calzetti et al. for local starburst galaxies. However, over the mass range 7.2 < log M/Msolar < 10.2, the slope of the attenuation law in the UV is shallower than t...

  10. Far-ultraviolet MAMA detector imagery and emission-line CCD imagery of NGC 6240

    Science.gov (United States)

    Smith, Andrew M.; Hill, Robert S.; Vrba, Frederick J.; Timothy, J. G.

    1992-01-01

    An image of the luminous infrared galaxy NGC 6240 at 1480 A was obtained using a multianode microchannel array (MAMA) detector with a rocket-borne telescope. At distances greater than 12 arcsec from the nucleus, the measured ultraviolet luminosity implies intensive star formation activity equal to 2-3 times that of a spiral galaxy such as M83. Optical images in the H-beta and forbidden O III 5007 A emission lines reveal a region of high excitation east of the nucleus between the centers of disks 1 and 2 as described by Bland-Hawthorn et al.

  11. High-excitation emission lines near eta Carinae, and its likely companion star

    OpenAIRE

    Mehner, Andrea; Davidson, Kris; Ferland, Gary J.; Humphreys, Roberta M.

    2009-01-01

    In order to study the distribution of gas and ionizing radiation around eta Car and their implications for its likely companion star, we have examined high-excitation emission lines of [Ne III], [Fe III], etc., in spectra obtained with the HST/STIS instrument during 1998-2004. Our principal results, some of them unexpected, are: (1) The high-excitation fluxes varied systematically and non-trivially throughout eta Car's 5.5-year spectroscopic cycle. Instead of rising to a plateau after the 199...

  12. THE MOSDEF SURVEY: DISSECTING THE STAR FORMATION RATE VERSUS STELLAR MASS RELATION USING Hα AND Hβ EMISSION LINES AT z ∼ 2

    Energy Technology Data Exchange (ETDEWEB)

    Shivaei, Irene; Reddy, Naveen A.; Siana, Brian; Mobasher, Bahram; Freeman, William R.; Groot, Laura de [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Shapley, Alice E.; Sanders, Ryan [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Kriek, Mariska; Price, Sedona H. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Coil, Alison L.; Azadi, Mojegan [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States)

    2015-12-20

    We present results on the star formation rate (SFR) versus stellar mass (M{sub *}) relation (i.e., the “main sequence”) among star-forming galaxies at 1.37 ≤ z ≤ 2.61 using the MOSFIRE Deep Evolution Field (MOSDEF) survey. Based on a sample of 261 galaxies with Hα and Hβ spectroscopy, we have estimated robust dust-corrected instantaneous SFRs over a large range in M{sub *} (∼10{sup 9.5}–10{sup 11.5} M{sub ⊙}). We find a correlation between log(SFR(Hα)) and log(M{sub *}) with a slope of 0.65 ± 0.08 (0.58 ± 0.10) at 1.4 < z < 2.6 (2.1 < z < 2.6). We find that different assumptions for the dust correction, such as using the color excess of the stellar continuum to correct the nebular lines, sample selection biases against red star-forming galaxies, and not accounting for Balmer absorption, can yield steeper slopes of the log(SFR)–log(M{sub *}) relation. Our sample is immune from these biases as it is rest-frame optically selected, Hα and Hβ are corrected for Balmer absorption, and the Hα luminosity is dust corrected using the nebular color excess computed from the Balmer decrement. The scatter of the log(SFR(Hα))–log(M{sub *}) relation, after accounting for the measurement uncertainties, is 0.31 dex at 2.1 < z < 2.6, which is 0.05 dex larger than the scatter in log(SFR(UV))–log(M{sub *}). Based on comparisons to a simulated SFR–M{sub *} relation with some intrinsic scatter, we argue that in the absence of direct measurements of galaxy-to-galaxy variations in the attenuation/extinction curves and the initial mass function, one cannot use the difference in the scatter of the SFR(Hα)– and SFR(UV)–M{sub *} relations to constrain the stochasticity of star formation in high-redshift galaxies.

  13. Untangling the Recombination Line Emission from HII Regions with Multiple Velocity Components

    CERN Document Server

    Anderson, L D; Wenger, T V; Bania, T M; Balser, Dana S

    2015-01-01

    HII regions are the ionized spheres surrounding high-mass stars. They are ideal targets for tracing Galactic structure because they are predominantly found in spiral arms and have high luminosities at infrared and radio wavelengths. In the Green Bank Telescope HII Region Discovery Survey (GBT HRDS) we found that >30% of first Galactic quadrant HII regions have multiple hydrogen radio recombination line (RRL) velocities, which makes determining their Galactic locations and physical properties impossible. Here we make additional GBT RRL observations to determine the discrete HII region velocity for all 117 multiple-velocity sources within 18deg. < l < 65deg. The multiple-velocity sources are concentrated in the zone 22deg. < l < 32deg., coinciding with the largest regions of massive star formation, which implies that the diffuse emission is caused by leaked ionizing photons. We combine our observations with analyses of the electron temperature, molecular gas, and carbon recombination lines to determ...

  14. Suppression of Fiber Modal Noise Induced Radial Velocity Errors for Bright Emission-Line Calibration Sources

    CERN Document Server

    Mahadevan, Suvrath; Ramsey, Lawrence; Venditti, Nick

    2014-01-01

    Modal noise in optical fibers imposes limits on the signal to noise and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity (RV) spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high signal to noise. Many of these spectrographs plan to use highly coherent emission line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial mass planets. These high precision calibration sources often use single mode fibers or highly coherent sources. Coupling light from single mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf (COTS) solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to...

  15. Gamma-ray line emission from 26Al produced by Wolf-Rayet stars

    International Nuclear Information System (INIS)

    The recent satellite observations of the 1.8 MeV line from the decay of 26Al has given a new impetus to the study of the nucleosynthesis of 26Al. In this communication we discuss the production and ejection of 26Al by massive mass-losing stars (Of and WR stars), in the light of recent stellar models. We also derive the longitude distribution of the 26Al gamma-ray line emission produced by the galactic collection of WR stars, based on various estimates of their radial distribution. This longitude profile provides i) a specific signature of massive stars on the background of other potential 26Al sources, as novae, supernovae, certain red giants and possibly AGB stars and ii) a possible tool to improve the data analysis of the HEAO 3 and SMM experiments

  16. Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495.

    Science.gov (United States)

    Fabian, A C; Zoghbi, A; Ross, R R; Uttley, P; Gallo, L C; Brandt, W N; Blustin, A J; Boller, T; Caballero-Garcia, M D; Larsson, J; Miller, J M; Miniutti, G; Ponti, G; Reis, R C; Reynolds, C S; Tanaka, Y; Young, A J

    2009-05-28

    Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG-6-30-15 (ref. 1), broad iron K lines have been found in emission from several other Seyfert galaxies, from accreting stellar-mass black holes and even from accreting neutron stars. The iron K line is prominent in the reflection spectrum created by the hard-X-ray continuum irradiating dense accreting matter. Relativistic distortion of the line makes it sensitive to the strong gravity and spin of the black hole. The accompanying iron L-line emission should be detectable when the iron abundance is high. Here we report the presence of both iron K and iron L emission in the spectrum of the narrow-line Seyfert 1 galaxy 1H 0707-495. The bright iron L emission has enabled us to detect a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the black hole. The observed reverberation timescale is comparable to the light-crossing time of the innermost radii around a supermassive black hole. The combination of spectral and timing data on 1H 0707-495 provides strong evidence that we are witnessing emission from matter within a gravitational radius, or a fraction of a light minute, from the event horizon of a rapidly spinning, massive black hole. PMID:19478778

  17. Line broadening caused by Coulomb carrier-carrier correlations and dynamics of carrier capture and emission in quantum dots

    DEFF Research Database (Denmark)

    Uskov, Alexander V; Magnúsdóttir, Ingibjörg; Tromborg, Bjarne;

    2001-01-01

    Mechanisms of pure dephasing in quantum dots due to Coulomb correlations and the dynamics of carrier capture and emission are suggested, and a phenomenological model for the dephasing is developed. It is shown that, if the rates of these capture and emission processes are sufficiently high, signi......, significant homogeneous line broadening of the order of several meV can result....

  18. The Importance of Broad Emission-Line Widths in Single Epoch Black Hole Mass Estimates

    CERN Document Server

    Assef, R J; Grier, C J; Kochanek, C S; Denney, K D; Peterson, B M

    2012-01-01

    Estimates of the mass of super-massive black holes (BHs) in distant active galactic nuclei (AGNs) can be obtained efficiently only through single-epoch spectra, using a combination of their broad emission-line widths and continuum luminosities. Yet the reliability and accuracy of the method, and the resulting mass estimates, M_BH, remain uncertain. A recent study by Croom using a sample of SDSS, 2QZ and 2SLAQ quasars suggests that line widths contribute little information about the BH mass in these single-epoch estimates and can be replaced by a constant value without significant loss of accuracy. In this Letter, we use a sample of nearby reverberation-mapped AGNs to show that this conclusion is not universally applicable. We use the bulge luminosity (L_Bulge) of these local objects to test how well the known M_BH - L_Bulge correlation is recovered when using randomly assigned line widths instead of the measured ones to estimate M_BH. We find that line widths provide significant information about M_BH, and th...

  19. Detection of CI line emission from the detached CO shell of the AGB star R Sculptoris

    CERN Document Server

    Olofsson, Hans; Lindqvist, Michael

    2015-01-01

    Stars on the asymptotic giant branch (AGB) lose substantial amounts of matter, to the extent that they are important for the chemical evolution of, and dust production in, the universe. The mass loss is believed to increase gradually with age on the AGB, but it may also occur in the form of bursts, possibly related to the thermal pulsing phenomenon. Detached, geometrically thin, CO shells around carbon stars are good signposts of brief and intense mass ejection. We aim to put further constraints on the physical properties of detached CO shells around AGB stars. The photodissociation of CO and other carbon-bearing species in the shells leads to the possibility of detecting lines from neutral carbon. We have therefore searched for the CI($^3P_1-\\,^3P_0$) line at 492 GHz towards two carbon stars, S Sct and R Scl, with detached CO shells of different ages, about 8000 and 2300 years, respectively. The CI($^3P_1-\\,^3P_0$) line was detected towards R Scl. The line intensity is dominated by emission from the detached...

  20. Evidence of the Link between Broad Emission Line Regions and Accretion Disks in Active Galactic Nuclei

    Institute of Scientific and Technical Information of China (English)

    Yun Xu; Xin-Wu Cao

    2007-01-01

    There is observational evidence that broad-line regions (BLRs) exist in most active galactic nuclei (AGNs), but their origin is still unclear. One scenario is that the BLRs originate from winds accelerated from the hot coronae of the disks, and the winds are suppressed when the black hole is accreting at low rates. This model predicts a relation between (m) ((m) = (M)/(M)Edd) and the FWHM of broad emission lines. We estimate the central black hole masses for a sample of bright AGNs by using their broad Hβ line-widths and optical luminosities. The dimensionless accretion rates (m) = (M)/(M)Edd are derived from the optical continuum luminosities by using two different models: using an empirical relation between the bolometric luminosity Lbol and the optical luminosity ((m) = Lbol/LEdd, a fixed radiative efficiency is adopted); and calculating the optical spectra of accretion disks as a function of (m). We find a significant correlation between the derived (m) and the observed line width of Hβ,FWHM∝ (m)-0.37, which almost overlaps the disk-corona model calculations, if the viscosity α≈ 0.1 - 0.2 is adopted. Our results provide strong evidence for the physical link between the BLRs and accretion disks in AGNs.

  1. The Soft X-ray and Narrow-line Emission of Mrk 573 on Kiloparsec Scales

    Science.gov (United States)

    Gonzalez-Martin, O.; Acosta-Pulido, J. A.; Perez Garcia, A. M.; Ramos Almeida, C.

    2010-11-01

    We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk 573 using Chandra, XMM-Newton, and Hubble Space Telescope (HST) data. We have studied the morphology of the soft (soft X-ray emission is resolved into a complex extended region. The X-ray morphology shows a biconical region extending up to 12 arcsec (4 kpc) in projection from the nucleus. A strong correlation between the X-rays and the highly ionized gas seen in the [O III]λ5007 Å image is reported. Moreover, we have studied the line intensities detected with the XMM-Newton Reflection Grating Spectrometer (RGS) and used them to fit the low-resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS/XMM-Newton spectrum is dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among other highly ionized species. A good fit is obtained using these emission lines found in the RGS/XMM-Newton spectrum as a template for Chandra spectra of the nucleus and extended emission, coincident with the cone-like structures seen in the [O III]/Hα map. The photoionization model Cloudy provides a reasonable fit for both the nuclear region and the cone-like structures showing that the dominant excitation mechanism is photoionization. For the nucleus the emission is modeled using two phases: a high ionization [log (U) = 1.23] and a low ionization [log (U) = 0.13]. For the high-ionization phase the transmitted and reflected components are in a 1:2 ratio, whereas for the low ionization the reflected component dominates. For the extended emission, we successfully reproduced the emission with two phases. The first phase shows a higher ionization parameter for the northwest (log (U) = 0.9) than for the southeast cone (log (U) = 0.3). Moreover, this phase is transmission dominated for the southeast cone and reflection dominated for the northwest cone. The second phase shows a low-ionization parameter (log (U) = -3) and is rather uniform for northwest and southeast cones and equally distributed

  2. The Number Density Evolution of Extreme Emission Line Galaxies in 3D-HST: Results from a Novel Automated Line Search Technique for Slitless Spectroscopy

    CERN Document Server

    Maseda, Michael V; Rix, Hans-Walter; Momcheva, Ivelina; Brammer, Gabriel B; Franx, Marijn; Lundgren, Britt F; Skelton, Rosalind E; Whitaker, Katherine E

    2016-01-01

    The multiplexing capability of slitless spectroscopy is a powerful asset in creating large spectroscopic datasets, but issues such as spectral confusion make the interpretation of the data challenging. Here we present a new method to search for emission lines in the slitless spectroscopic data from the 3D-HST survey utilizing the Wide-Field Camera 3 on board the Hubble Space Telescope. Using a novel statistical technique, we can detect compact (extended) emission lines at 90% completeness down to fluxes of 1.5 (3.0) times 10^{-17} erg/s/cm^2, close to the noise level of the grism exposures, for objects detected in the deep ancillary photometric data. Unlike previous methods, the Bayesian nature allows for probabilistic line identifications, namely redshift estimates, based on secondary emission line detections and/or photometric redshift priors. As a first application, we measure the comoving number density of Extreme Emission Line Galaxies (restframe [O III] 5007 equivalent widths in excess of 500 Angstroms)...

  3. Design of a portable optical emission tomography system for microwave induced compact plasma for visible to near-infrared emission lines

    Science.gov (United States)

    Rathore, Kavita; Munshi, Prabhat; Bhattacharjee, Sudeep

    2016-03-01

    A new non-invasive diagnostic system is developed for Microwave Induced Plasma (MIP) to reconstruct tomographic images of a 2D emission profile. A compact MIP system has wide application in industry as well as research application such as thrusters for space propulsion, high current ion beams, and creation of negative ions for heating of fusion plasma. Emission profile depends on two crucial parameters, namely, the electron temperature and density (over the entire spatial extent) of the plasma system. Emission tomography provides basic understanding of plasmas and it is very useful to monitor internal structure of plasma phenomena without disturbing its actual processes. This paper presents development of a compact, modular, and versatile Optical Emission Tomography (OET) tool for a cylindrical, magnetically confined MIP system. It has eight slit-hole cameras and each consisting of a complementary metal-oxide-semiconductor linear image sensor for light detection. The optical noise is reduced by using aspheric lens and interference band-pass filters in each camera. The entire cylindrical plasma can be scanned with automated sliding ring mechanism arranged in fan-beam data collection geometry. The design of the camera includes a unique possibility to incorporate different filters to get the particular wavelength light from the plasma. This OET system includes selected band-pass filters for particular argon emission 750 nm, 772 nm, and 811 nm lines and hydrogen emission Hα (656 nm) and Hβ (486 nm) lines. Convolution back projection algorithm is used to obtain the tomographic images of plasma emission line. The paper mainly focuses on (a) design of OET system in detail and (b) study of emission profile for 750 nm argon emission lines to validate the system design.

  4. Spectroscopy of southern Galactic disk planetary nebulae. Notes on chemical composition and emission-line stars

    CERN Document Server

    Górny, S K

    2014-01-01

    We present low resolution spectroscopic observations for a sample of 53 planetary nebulae (PNe) located in the southern sky between Vela and Norma constellations and pertaining to the Galactic disk with expected Galactocentric distance range of 5 to 10 kpc. We derive nebular chemical composition and plasma parameters with the classical empirical method. For most of the observed objects it is done for the first time. The distributions of the chemical abundances of the observed disk sample are generally indistinguishable from Galactic bulge and inner-disk PNe populations. The exceptions are possible differences in He/H distribution comparing to bulge PNe and Ne/Ar comparing to inner-disk PNe sample. The derived O/H ratios for the observed disk PNe fit to the concept of flattening of the chemical gradient in the inner parts of the Milky Way. We use the spectra to search for emission-line central stars in the observed sample. We found 6 new emission-line central stars comprising examples of all known types: WEL, ...

  5. Magnetically elevated accretion disks in active galactic nuclei: broad emission line regions and associated star formation

    Science.gov (United States)

    Begelman, Mitchell C.; Silk, Joseph

    2016-10-01

    We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal (φ -direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at R to large heights z ˜ 0.1 R and low densities, while leaving a thin dense layer containing most of the mass - but contributing very little accretion - around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: the formation of broad emission line regions and the suppression of fragmentation thought to inhibit accretion at the required rates. We show that the disk of stars that formed in the Galactic Center a few million years ago could have resulted from an episode of magnetically elevated accretion at ˜0.1 of the Eddington limit.

  6. Time-Dependent MHD Shocks and Line Emission: The Case of the DG Tau Jet

    CERN Document Server

    Massaglia, S; Bodo, G

    2005-01-01

    The line emission from a growing number of Herbig-Haro jets can be observed and resolved at angular distances smaller than a few arcseconds from the central source. The interpretation of this emission is problematic, since the simplest model of a cooling jet cannot sustain it. It has been suggested that what one actually observes are shocked regions with a filling factor of $\\sim 1%$. In this framework, up to now, comparisons with observations have been based on stationary shock models. Here we introduce for the first time the self-consistent dynamics of such shocks and we show that considering their properties at different times, i.e. locations, we can reproduce observational data of the DG Tau microjet. In particular, we can interpret the spatial behavior of the [SII]6716/6731 and [NII]/[OI]6583/6300 line intensity ratios adopting a set of physical parameters that yield values of mass loss rates and magnetic fields consistent with previous estimates. We also obtain the values of the mean ionization fraction...

  7. Wide-Field Survey of Emission-line Stars in IC 1396

    CERN Document Server

    Nakano, M; Watanabe, M; Fukuda, N; Ishihara, D; Ueno, M

    2012-01-01

    We have made an extensive survey of emission-line stars in the IC 1396 HII region to investigate the low-mass population of pre-main sequence (PMS) stars. A total of 639 H-alpha emission-line stars were detected in an area of 4.2 deg^2 and their i'-photometry was measured. Their spatial distribution exhibits several aggregates near the elephant trunk globule (Rim A) and bright-rimmed clouds at the edge of the HII region (Rim B and SFO 37, 38, 39, 41), and near HD 206267, which is the main exciting star of the HII region. Based on the extinction estimated from the near-infrared (NIR) color-color diagram, we have selected pre-main sequence star candidates associated with IC 1396. The age and mass were derived from the extinction corrected color-magnitude diagram and theoretical pre-main sequence tracks. Most of our PMS candidates have ages of < 3 Myr and masses of 0.2-0.6 Mo. Although it appears that only a few stars were formed in the last 1 Myr in the east region of the exciting star, the age difference am...

  8. CLASH: Extreme Emission Line Galaxies and Their Implication on Selection of High-Redshift Galaxies

    CERN Document Server

    Huang, Xingxing; Wang, Junxian; Ford, Holland; Lemze, Doron; Moustakas, John; Shu, Xinwen; Van der Wel, Arjen; Zitrin, Adi; Frye, Brenda L; Postman, Marc; Bartelmann, Matthias; Benitez, Narciso; Bradley, Larry; Broadhurst, Tom; Coe, Dan; Donahue, Megan; Infante, Leopoldo; Kelson, Daniel; Koekemoer, Anton; Lahav, Ofer; Medezinski, Elinor; Moustakas, Leonidas; Rosati, Piero; Seitz, Stella; Umetsu, Keiichi

    2014-01-01

    We utilize the CLASH (Cluster Lensing And Supernova survey with Hubble) observations of 25 clusters to search for extreme emission-line galaxies (EELGs). The selections are carried out in two central bands: F105W (Y105) and F125W (J125), as the flux of the central bands could be enhanced by the presence of [O III] 4959, 5007 at redshift of about 0.93-1.14 and 1.57-1.79, respectively. The multi-band observations help to constrain the equivalent widths of emission lines. Thanks to cluster lensing, we are able to identify 52 candidates down to an intrinsic limiting magnitude of 28.5 and to a rest-frame [O III] 4959,5007 equivalent width of about 3737 angstrom. Our samples include a number of EELGs at lower luminosities that are missed in other surveys, and the extremely high equivalent width can be only found in such faint galaxies. These EELGs can mimic the dropout feature similar to that of high redshift galaxies and contaminate the color-color selection of high redshift galaxies when the S/N ratio is limited ...

  9. Application of artificial neural networks to a nanoflare model of active region emission line radiance

    CERN Document Server

    Bazarghan, M; Innes, D E; Karami, E; Solanki, S K

    2008-01-01

    Context. Nanoflares are small impulsive bursts of energy that blend with and possibly make up much of the solar background emission. Determining their frequency and energy input is central to understanding the heating of the solar corona. One method is to extrapolate the energy frequency distribution of larger individually observed flares to lower energies. Only if the power law exponent is greater than 2, is it considered possible that nanoflares contribute significantly to the energy input. Aims. Time sequences of ultraviolet line radiances observed in the corona of an active region are modelled with the aim of determining the power law exponent of the nanoflare energy distribution. Methods. A simple nanoflare model based on three key parameters (the flare rate, the flare duration time, and the power law exponent of the flare energy frequency distribution) is used to simulate emission line radiances from the ions Fe XIX, Ca XIII, and Si iii, observed by SUMER in the corona of an active region as it rotates ...

  10. The evolution of the [OII], H{\\beta} and [OIII] emission-line luminosity functions

    CERN Document Server

    Comparat, Johan; Perez-Gonzalez, Violeta; Norberg, Peder; Newman, Jeffrey; Tresse, Laurence; Richard, Johan; Yepes, Gustavo; Kneib, Jean-Paul; Raichoor, Anand; Prada, Francisco; Maraston, Claudia; Yèche, Christophe; Delubac, Timothée; Jullo, Eric

    2016-01-01

    Emission-line galaxies (ELGs) are one of the main tracers of the large-scale structure to be targeted by the next-generation dark energy surveys. To provide a better understanding of the properties and statistics of these galaxies, we have collected spectroscopic data from the VVDS and DEEP2 deep surveys and estimated the galaxy luminosity functions (LFs) of three distinct emission lines, [OII], H$\\beta$ and [OIII] at redshifts ($0.2 < z < 1.3$). Our measurements are based on the largest sample so far. We present the first measurement of the \\Hb LF at these redshifts. We have also compiled LFs from the literature that were based on independent data or covered different redshift ranges, and we fit the entire set over the whole redshift range with analytic Schechter and Saunders models, assuming a natural redshift dependence of the parameters. We find that the characteristic luminosity ($L_*$) and density ($\\phi_*$) of all LFs increase with redshift. Using the Schechter model, we find that $L^*$ of [OII] ...

  11. Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction

    CERN Document Server

    Wang, Lile; Ju, Wenhua; Rafikov, Roman R; Ruan, John J; Schneider, Donald P

    2016-01-01

    Supermassive black hole binaries (SMBHs) are expected to result from galaxy mergers, and thus are natural byproducts (and probes) of hierarchical structure formation in the Universe. They are also the primary expected source of low-frequency gravitational wave emission. We search for binary BHs using time-variable velocity shifts in broad Mg II emission lines of quasars with multi-epoch observations. First, we inspect velocity shifts of the binary SMBH candidates identified in Ju et al. (2013), using SDSS spectra with an additional epoch of data that lengthens the typical baseline to ~10 yr. We find variations in the line-of-sight velocity shifts over 10 years that are comparable to the shifts observed over 1-2 years, ruling out the binary model for the bulk of our candidates. We then analyze 1438 objects with 8 yr median time baselines, from which we would expect to see velocity shifts >1000 km/s from sub-pc binaries. We find only one object with an outlying velocity of 448 km/s, indicating, based on our mod...

  12. High-excitation emission lines near eta Carinae, and its likely companion star

    CERN Document Server

    Mehner, Andrea; Ferland, Gary J; Humphreys, Roberta M

    2009-01-01

    In order to study the distribution of gas and ionizing radiation around eta Car and their implications for its likely companion star, we have examined high-excitation emission lines of [Ne III], [Fe III], etc., in spectra obtained with the HST/STIS instrument during 1998-2004. Our principal results, some of them unexpected, are: (1) The high-excitation fluxes varied systematically and non-trivially throughout eta Car's 5.5-year spectroscopic cycle. Instead of rising to a plateau after the 1998 "event," they changed continuously with a maximum in mid-cycle. (2) At one significant location a brief, strong secondary maximum occurred just before the 2003.5 spectroscopic event. (3) These emission lines are strongly concentrated at the "Weigelt knots" several hundred AU northwest of the star. With less certainty, [Ne III] appears to be somewhat more concentrated than [Fe III]. (4) A faster, blue-shifted component of each feature appears concentrated near the star and elongated perpendicular to the system's bipolar ...

  13. Locally Optimally-Emitting Clouds and the Variable Broad Emission Line Spectrum of NGC 5548

    CERN Document Server

    Korista, K T; Korista, Kirk T.; Goad, Michael R.

    2000-01-01

    [abridged] We test the ``locally optimally-emitting clouds'' (LOC) model against the extensive spectroscopic data base of the Seyfert~1, NGC 5548. The time-averaged, integrated-light UV broad emission line spectrum from the 1993 global geometric parameters: the outer radius, the index controlling the radial cloud covering fraction of the continuum source, and the integrated cloud covering fraction. We make an {\\em ad~hoc} selection from the range of successful models, and for a simple spherical BLR geometry we simulate the emission line light curves for the 1989 {\\em IUE} and 1993 {\\em HST} campaigns, using the respective observed UV continuum light curves as drivers. We find good agreement between the predicted and observed light curves and lags --- a demonstration of the LOC picture's viability as a means to understanding the BLR environment. Finally, we discuss the next step in developing the LOC picture which involves the marriage of echo-mapping techniques with spectral simulation grids such as those pre...

  14. Photometric redshifts and clustering of emission line galaxies selected jointly by DES and eBOSS

    CERN Document Server

    Jouvel, S; Comparat, J; Carnero, A; Camacho, H; Abdalla, F B; Kneib, J-P; Merson, A; Lima, M; Sobreira, F; da Costa, Luiz; Prada, F; Zhu, G B; Benoit-Levy, A; De La Macora, A; Kuropatkin, N; Lin, H; Abbott, T M C; Allam, S; Banerji, M; Bertin, E; Brooks, D; Capozzi, D; Kind, M Carrasco; Carretero, J; Castander, F J; Cunha, C E; Desai, S; Doel, P; Eifler, T F; Estrada, J; Neto, A Fausti; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Lahav, O; Li, T S; Maia, M A G; March, M; Marshall, J L; Miquel, R; Percival, W J; Plazas, A A; Reil, K; Romer, A K; Roodman, A; Rykoff, E S; Sako, M; Sanchez, E; Santiago, B; Scarpine, V; Sevilla-Noarbe, I; Santos, M Soares; Suchyta, E; Tarle, G; Thaler, J; Thomas, D; Walker, A; Zhang, Y

    2015-01-01

    We present the results of the first test plates of the extended Baryon Oscillation Spectroscopic Survey. This paper focuses on the emission line galaxies (ELG) population targetted from the Dark Energy Survey (DES) photometry. We analyse the success rate, efficiency, redshift distribution, and clustering properties of the targets. From the 9000 spectroscopic redshifts targetted, 4600 have been selected from the DES photometry. The total success rate for redshifts between 0.6 and 1.2 is 71\\% and 68\\% respectively for a bright and faint, on average more distant, samples including redshifts measured from a single strong emission line. We find a mean redshift of 0.8 and 0.87, with 15 and 13\\% of unknown redshifts respectively for the bright and faint samples. In the redshift range 0.6

  15. The CIDA-UCM-Yale Shallow Survey for Emission Line Galaxies

    CERN Document Server

    Bongiovanni, A; Magris, G; Gallego, J; García-Dabo, C E; Coppi, P; Sabbey, C

    2005-01-01

    We present the CIDA-UCM-Yale (Centro de Investigaciones de Astronomia, Universidad Complutense de Madrid and Yale University) survey for Halpha+[NII]6549,6584 emission-line galaxies using objective-prism spectra. The most important properties of a catalogue with 427 entries and significant subsets are analysed. The complete sample contains 183 statistically confirmed ELGs in a sky area of 151 sq.deg. and redshift up to 0.14. We determine the parameters of the Halpha luminosity function using the Halpha+[NII] flux directly measured on the ELGs spectra in this sample and the star formation rate density derived is in agreement with the values reported in the literature. Finally, we study the clustering properties of local star-forming galaxies relative to quiescent ones from different perspectives. We find that emission-line galaxies avoid dense regions of quiescent galaxies and we propose a power-law expression to parametrise the relation between star formation rate density and environment volume density of emi...

  16. X-ray narrow emission lines from the nuclear region of NGC 1365

    CERN Document Server

    Whewell, M; Page, M J

    2016-01-01

    NGC 1365 is a Seyfert 2 galaxy with a starburst ring in its nuclear region. In this work we look at the XMM Reflection Grating Spectrometer (RGS) data from four 2012-13, three 2007 and two 2004 observations of NGC 1365. We characterise the narrow-line emitting gas visible by XMM RGS and make comparisons between the 2012-13 spectra and those from 2004-07, already published. This source is usually absorbed within the soft X-ray band, with a typical neutral column density of >1.5 x 10$^{23}$ cm$^{-2}$, and only 1 observation of the 9 we investigate shows low enough absorption for the continuum to emerge in the soft X-rays. We stack all observations from 2004-07, and separately three of the four observations from 2012-13, analysing the less absorbed observation separately. We first model the spectra using gaussian profiles representing the narrow line emission. We fit physically motivated models to the 2012-13 stacked spectra, with collisionally ionised components representing the starburst emission and photoioni...

  17. Fluorescent H_2 Emission Lines from the Reflection Nebula NGC 7023 Observed with IGRINS

    CERN Document Server

    Le, Huynh Anh N; Kaplan, Kyle F; Mace, Gregory N; Lee, Sungho; Pavel, Michael D; Jeong, Ueejeong; Oh, Heeyoung; Lee, Hye-In; Chun, Moo-Young; Yuk, In-Soo; Pyo, Tae-Soo; Hwang, Narae; Kim, Kang-Min; Park, Chan; Oh, Jae Sok; Yu, Young S; Park, Byeong-Gon; Minh, Young Chol; Jaffe, Daniel T

    2016-01-01

    We have analyzed the temperature, velocity and density of H_2 gas in NGC 7023 with a high-resolution near-infrared spectrum of the northwestern filament of the reflection nebula. By observing NGC 7023 in the H and K bands at R ~ 45,000 with the Immersion GRating INfrared Spectrograph (IGRINS), we detected 70 H_2 emission lines within the 1" x 15" slit. The diagnostic ratios of 2-1 S(1)/1-0 S(1) are 0.39-0.54. In addition, the estimated ortho-to-para ratios (OPR) are 1.57-1.62, indicating that the H_2 transitions in the observed regions are mostly from UV fluorescence. Gradients in the temperature, velocity, and OPR of the observed areas imply motion of the photodissociation region (PDR) relative to the molecular cloud. In addition, we derive the column density of H_2 from the observed emission lines and compare these results with PDR models in the literature covering a range of densities and incident UV field intensities. The notable difference between PDR model predictions and the observed data, in high rota...

  18. Spectral optical monitoring of a double-peaked emission line AGN Arp 102B: I. Variability of spectral lines and continuum

    CERN Document Server

    Shapovalova, A I; Burenkov, A N; Chavushyan, V H; Ilic, D; Kollatschny, W; Kovacevic, A; Bochkarev, N G; Valdes, J R; Torrealba, J; Patino-Alvarez, V; Leon-Tavares, J; Benitez, E; Carrasco, L; Dultzin, D; Mercado, A; Zhdanova, V E

    2013-01-01

    Here we present results of the long-term (1987-2010) optical spectral monitoring of the broad line radio galaxy Arp 102B, a prototype of active galactic nuclei with the double-peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore the structure of the broad line region (BLR), we analyze the light curves of the broad H\\alpha and H\\beta lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. We use the CCF to find lags between the lines and continuum variations. We investigate in more details the correlation between line and continuum fluxes, moreover we explore periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms. The line and continuum light curves show several flare-like events. The fluxes in lines and in the continuum are not showing a big change (around 20%) during the monitoring period. We found a small correlation between the line and continuum flux...

  19. Long Fading Mid-Infrared Emission in Transient Coronal Line Emitters: Dust Echo of Tidal Disruption Flare

    OpenAIRE

    Dou, Liming; Wang, Ting-Gui; Jiang, Ning; Yang, Chenwei; Lyu, Jianwei; Zhou, Hongyan

    2016-01-01

    The sporadic accretion followed the tidal disruption of a star by a supermassive black hole leads to a bright UV and soft X-ray flare in the galactic nucleus. The gas and dust surrounding the black hole responses to such a flare with an echo in emission lines and infrared emission. In this paper, we report the detection of long fading mid-IR emission lasting up to 14 years after the flare in four TDE candidates with transient coronal lines using the WISE public data release. We estimate repro...

  20. Excitation wavelength dependence of water-window line emissions from boron-nitride laser-produced plasmas

    OpenAIRE

    Crank, M.; Harilal, S. S.; S.M. Hassan; Hassanein, A.

    2012-01-01

    We investigated the effects of laser excitation wavelength on water-window emission lines of laser-produced boron-nitride plasmas. Plasmas are produced by focusing 1064 nm and harmonically generated 532 and 266 nm radiation from a Nd:YAG laser on BN target in vacuum. Soft x-ray emission lines in the water-window region are recorded using a grazing-incidence spectrograph. Filtered photodiodes are used to obtain complementary data for water-window emission intensity and angular dependence. Spec...

  1. Tomographic imaging system for measuring impurity line emission in a field-reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Roche, T.; Heidbrink, W. W.; McWilliams, R. [University of California, Irvine, California 92697 (United States); Bolte, N.; Garate, E.; Wessel, F. [University of California, Irvine, California 92697 (United States); Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2012-10-15

    A 16 chord optical tomography system has been developed and implemented in the flux coil generated-field reversed configuration (FRC). The chords are arranged in two fans of eight, which cover {approx}35% of the vessel area at the midplane. Each illuminate separate photomultiplier tubes (PMTs) which are fitted with narrow band-pass filters. In this case, filters are centered at 434.8 nm to measure emission from singly ionized argon. PMT crosstalk is negligible. Background noise due to electron radiation and H{sub {gamma}} line radiation is <10% of argon emission. The spatial resolution of the reconstruction is 1.5 cm. Argon is introduced using a puff valve and tube designed to impart the gas into the system as the FRC is forming. Reconstruction of experimental data results in time-dependent, 2D emissivity profiles of the impurity ions. Analysis of these data show radial, cross-field diffusion to be in the range of 10-10{sup 3} m{sup 2}/s during FRC equilibrium.

  2. C IV and He II Line Emission of Lyman Alpha Blobs: Powered by Shock Heated Gas

    CERN Document Server

    Cabot, Samuel H C; Zheng, Zheng

    2016-01-01

    Utilizing {\\it ab initio} ultra-high resolution hydrodynamical simulations, we investigate the properties of the interstellar and circum-galactic medium of Ly$\\alpha$ Blobs (LABs) at $z=3$, focusing on three important emission lines: Ly$\\alpha$ 1216\\AA, \\heii 1640\\AA\\ and \\civ 1449\\AA. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed \\civ/\\lya\\ and \\heii/\\lya\\ ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation, and the \\civ/Ly$\\alpha$ and \\heii/Ly$\\alpha$ ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the \\lya\\ emission, the \\lya\\ and \\civ\\ emission...

  3. VLBI IMAGING OF THE DOUBLE PEAKED EMISSION LINE SEYFERT KISSR 1494

    Energy Technology Data Exchange (ETDEWEB)

    Kharb, P.; Das, M.; Subramanian, S.; Chitta, L. P. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Paragi, Z., E-mail: kharb@iiap.res.in [Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo (Netherlands)

    2015-02-01

    We present here the results from dual-frequency phase-referenced Very Long Baseline Interferometry observations of the Seyfert galaxy KISSR 1494, which exhibits double peaked emission lines in its Sloan Digital Sky Survey spectrum. We detect a single radio component at 1.6 GHz, but not at 5 GHz, implying a spectral index steeper than –1.5 ± 0.5 (S {sub ν}∝ν{sup α}). The high brightness temperature of the radio component (∼1.4 × 10{sup 7} K) and the steep radio spectrum support a non-thermal synchrotron origin. A crude estimate of the black hole mass derived from the M {sub BH}-σ{sub *} relation is ∼1.4 ± 1.0 × 10{sup 8} M {sub ☉}; it is accreting at an Eddington rate of ∼0.02. The radio data are consistent with either the radio emission coming from the parsec-scale base of a synchrotron wind originating in the magnetized corona above the accretion disk, or from the inner ionized edge of the accretion disk or torus. In the former case, the narrow line region (NLR) clouds may form a part of the broad outflow, while in the latter, the NLR clouds may form a part of an extended disk beyond the torus. The radio and NLR emission may also be decoupled so that the radio emission originates in an outflow while the NLR is in a disk and vice versa. While with the present data it is not possible to clearly distinguish between these scenarios, there appears to be greater circumstantial evidence supporting the coronal wind picture in KISSR 1494. From the kiloparsec-scale radio emission, the time-averaged kinetic power of this outflow is estimated to be Q ≈ 1.5 × 10{sup 42} erg s{sup –1}, which is typical of radio outflows in low-luminosity active galactic nuclei. This supports the idea that radio ''jets'' and outflowing coronal winds are indistinguishable in Seyfert galaxies.

  4. Ultraviolet Emission Lines of Si ii in Quasars: Investigating the "Si ii Disaster"

    Science.gov (United States)

    Laha, Sibasish; Keenan, Francis P.; Ferland, Gary J.; Ramsbottom, Catherine A.; Aggarwal, Kanti M.

    2016-07-01

    The observed line intensity ratios of the Si ii λ1263 and λ1307 multiplets to that of Si ii λ1814 in the broad-line region (BLR) of quasars are both an order of magnitude larger than the theoretical values. This was first pointed out by Baldwin et al., who termed it the “Si ii disaster,” and it has remained unresolved. We investigate the problem in the light of newly published atomic data for Si ii. Specifically, we perform BLR calculations using several different atomic data sets within the CLOUDY modeling code under optically thick quasar cloud conditions. In addition, we test for selective pumping by the source photons or intrinsic galactic reddening as possible causes for the discrepancy, and we also consider blending with other species. However, we find that none of the options investigated resolve the Si ii disaster, with the potential exception of microturbulent velocity broadening and line blending. We find that a larger microturbulent velocity (˜ 500 {km} {{{s}}}-1) may solve the Si ii disaster through continuum pumping and other effects. The CLOUDY models indicate strong blending of the Si ii λ1307 multiplet with emission lines of O i, although the predicted degree of blending is incompatible with the observed λ1263/λ1307 intensity ratios. Clearly, more work is required on the quasar modeling of not just the Si ii lines but also nearby transitions (in particular those of O i) to fully investigate whether blending may be responsible for the Si ii disaster.

  5. The probability distribution functions of emission line flux measurements and their ratios

    Science.gov (United States)

    Wesson, R.; Stock, D. J.; Scicluna, P.

    2016-07-01

    Many physical parameters in astrophysics are derived using the ratios of two observed quantities. If the relative uncertainties on measurements are small enough, uncertainties can be propagated analytically using simplifying assumptions, but for large normally distributed uncertainties, the probability distribution of the ratio become skewed, with a modal value offset from that expected in Gaussian uncertainty propagation. Furthermore, the most likely value of a ratio A/B is not equal to the reciprocal of the most likely value of B/A. The effect is most pronounced when the uncertainty on the denominator is larger than that on the numerator. We show that this effect is seen in an analysis of 12 126 spectra from the Sloan Digital Sky Survey (SDSS). The intrinsically fixed ratio of the [O III] lines at 4959 and 5007 Å is conventionally expressed as the ratio of the stronger line to the weaker line. Thus, the uncertainty on the denominator is larger, and non-Gaussian probability distributions result. By taking this effect into account, we derive an improved estimate of the intrinsic 5007/4959 ratio. We obtain a value of 3.012 ± 0.008, which is slightly but statistically significantly higher than the theoretical value of 2.98. We further investigate the suggestion that fluxes measured from emission lines in noisy spectra are strongly biased upwards. We were unable to detect this effect in the SDSS line flux measurements, and we could not reproduce the results of Rola and Pelat who first described this bias. We suggest that the magnitude of this effect may depend strongly on the specific fitting algorithm used.

  6. A Link Between X-ray Emission Lines and Radio Jets in 4U 1630-47?

    CERN Document Server

    Neilsen, Joseph; Fender, Rob; Lee, Julia C; Ponti, Gabriele; Tzioumis, Tasso; Edwards, Phil; Broderick, Jess W

    2014-01-01

    Recently, Diaz Trigo et al. reported an XMM-Newton detection of relativistically Doppler-shifted emission lines associated with steep-spectrum radio emission in the stellar-mass black hole candidate 4U 1630-47 during its 2012 outburst. They interpreted these lines as indicative of a baryonic jet launched by the accretion disk. Here we present a search for the same lines earlier in the same outburst using high-resolution X-ray spectra from the Chandra High-Energy Transmission Grating Spectrometer. While our observations (eight months prior to the XMM-Newton campaign) also coincide with detections of steep spectrum radio emission by the Australia Telescope Compact Array, we find no evidence for any relativistic X-ray emission lines. Indeed, despite $\\sim5\\times$ brighter radio emission, our Chandra spectra allow us to place an upper limit on the flux in the blueshifted Fe XXVI line that is $\\gtrsim20\\times$ weaker than the line observed by Diaz Trigo et al. We explore several scenarios that could explain our di...

  7. UVES and X-Shooter spectroscopy of the emission line AM CVn systems GP Com and V396 Hya

    CERN Document Server

    Kupfer, T; Groot, P J; Marsh, T R; Nelemans, G; Roelofs, G H A

    2016-01-01

    We present time-resolved spectroscopy of the AM CVn-type binaries GP Com and V396 Hya obtained with VLT/X-Shooter and VLT/UVES. We fully resolve the narrow central components of the dominant helium lines and determine radial velocity semi-amplitudes of $K_{\\rm spike} = 11.7\\pm0.3$ km s$^{-1}$ for GP Com and $K_{\\rm spike} = 5.8\\pm0.3$ km s$^{-1}$ for V396 Hya. The mean velocities of the narrow central components show variations from line to line. Compared to calculated line profiles that include Stark broadening we are able to explain the displacements, and the appearance of forbidden helium lines, by additional Stark broadening of emission in a helium plasma with an electron density $n_e\\simeq 5\\times 10^{15}$ cm$^{-3}$. More than $30$ nitrogen and more than $10$ neon lines emission lines were detected in both systems. Additionally, $20$ nitrogen absorption lines are only seen in GP Com. The radial velocity variations of these lines show the same phase and velocity amplitude as the central helium emission co...

  8. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main sequence stars

    CERN Document Server

    Mendigutía, I; Rigliaco, E; Fairlamb, J R; Calvet, N; Muzerolle, J; Cunningham, N; Lumsden, S L

    2015-01-01

    Correlations between the accretion luminosity and emission line luminosities (L_acc and L_line) of pre-main sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) L_acc-L_line correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L_star) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the L_acc-L_line correlations depend on the L_acc-L_star relationship. We conclude that because PMS stars show the L_acc-L_star correlation immediately implies that L_acc also correlates with the luminosity of all emission lines, for which the L_acc-L_line correlations alone do not prove any phy...

  9. A support vector machine for spectral classification of emission-line galaxies from the Sloan Digital Sky Survey

    Science.gov (United States)

    Shi, Fei; Liu, Yu-Yan; Sun, Guang-Lan; Li, Pei-Yu; Lei, Yu-Ming; Wang, Jian

    2015-10-01

    The emission-lines of galaxies originate from massive young stars or supermassive blackholes. As a result, spectral classification of emission-line galaxies into star-forming galaxies, active galactic nucleus (AGN) hosts, or compositions of both relates closely to formation and evolution of galaxy. To find efficient and automatic spectral classification method, especially in large surveys and huge data bases, a support vector machine (SVM) supervised learning algorithm is applied to a sample of emission-line galaxies from the Sloan Digital Sky Survey (SDSS) data release 9 (DR9) provided by the Max Planck Institute and the Johns Hopkins University (MPA/JHU). A two-step approach is adopted. (i) The SVM must be trained with a subset of objects that are known to be AGN hosts, composites or star-forming galaxies, treating the strong emission-line flux measurements as input feature vectors in an n-dimensional space, where n is the number of strong emission-line flux ratios. (ii) After training on a sample of emission-line galaxies, the remaining galaxies are automatically classified. In the classification process, we use a 10-fold cross-validation technique. We show that the classification diagrams based on the [N II]/Hα versus other emission-line ratio, such as [O III]/Hβ, [Ne III]/[O II], ([O III]λ4959+[O III]λ5007)/[O III]λ4363, [O II]/Hβ, [Ar III]/[O III], [S II]/Hα, and [O I]/Hα, plus colour, allows us to separate unambiguously AGN hosts, composites or star-forming galaxies. Among them, the diagram of [N II]/Hα versus [O III]/Hβ achieved an accuracy of 99 per cent to separate the three classes of objects. The other diagrams above give an accuracy of ˜91 per cent.

  10. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

    Science.gov (United States)

    Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

    2010-01-01

    \\Ve compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 microns, [Ne II] 12.81 microns, [Ne III] 15.56 microns and [Ne V] 14.32 microns, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGNs are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT luminosities suggests that the emission lines primarily arise in gas ionized by the AGN. We also compared the mid-IR emission-lines in the BAT AGNs with those from published studies of star-forming galaxies and LINERs. We found that the BAT AGN fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. From this we found that sources that have been previously classified in the mid-infrared/optical as AGN have smaller emission line ratios than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGN represents the main contribution to the observed line emission. Overall, we present a different set of emission line diagnostics to distinguish between AGN and star forming galaxies that can be used as a tool to find new AGN.

  11. Neon Fine-Structure Line Emission By X-ray Irradiated Protoplanetary Disks

    CERN Document Server

    Glassgold, A E; Igea, J; Glassgold, Alfred E.; Najita, Joan R.; Igea, Javier

    2006-01-01

    Using a thermal-chemical model for the generic T-Tauri disk of D'Alessio et al. (1999), we estimate the strength of the fine-structure emission lines of NeII and NeIII at 12.81 and 15.55 microns that arise from the warm atmosphere of the disk exposed to hard stellar X-rays. The Ne ions are produced by the absorption of keV X-rays from the K shell of neutral Ne, followed by the Auger ejection of several additional electrons. The recombination cascade of the Ne ions is slow because of weak charge transfer with atomic hydrogen in the case of Ne2+ and by essentially no charge transfer for Ne+. For a distance of 140pc, the 12.81 micron line of Ne II has a flux of 1e-14 erg/cm2s, which should be observable with the Spitzer Infrared Spectrometer and suitable ground based instrumentation. The detection of these fine-structure lines would clearly demonstrate the effects of X-rays on the physical and chemical properties of the disks of young stellar objects and provide a diagnostic of the warm gas in protoplanetary dis...

  12. Centimeter searches for molecular line emission from high-redshift galaxies

    CERN Document Server

    Carilli, C L

    2002-01-01

    We consider the capabilities for detecting low order CO emission lines from high-z galaxies using the next generation of radio telescopes operating at 22 and 43 GHz. We employ models for the evolution of dusty star forming galaxies based on source counts at (sub)millimeter wavelengths, and on the observed mm through infrared backgrounds, to predict the expected detection rate of low-order CO(2-1) and CO(1-0) line emitting galaxies for optimal centimeter(cm)-wave surveys using future radio telescopes, such as the Square Kilometer Array (SKA) and the Expanded Very Large Array (EVLA). We then compare these results to surveys that can be done with the next-generation mm-wave telescope, the Atacama Large Millimeter Array (ALMA). Operating at 22 GHz the SKA will be competitive with the ALMA in terms of the detection rate of lines from high-z galaxies, and will be potentially superior by an order of magnitude if extended to 43 GHz. Perhaps more importantly, cm-wave telescopes are sensitive to lower excitation gas in...

  13. Shocks in dense clouds. IV. Effects of grain-grain processing on molecular line emission

    CERN Document Server

    Anderl, S; Forêts, G Pineau des; Flower, D R

    2014-01-01

    Grain-grain processing has been shown to be an indispensable ingredient of shock modelling in high density environments. For densities higher than \\sim10^5 cm-3, shattering becomes a self-enhanced process that imposes severe chemical and dynamical consequences on the shock characteristics. Shattering is accompanied by the vaporization of grains, which can directly release SiO to the gas phase. Given that SiO rotational line radiation is used as a major tracer of shocks in dense clouds, it is crucial to understand the influence of vaporization on SiO line emission. We have developed a recipe for implementing the effects of shattering and vaporization into a 2-fluid shock model, resulting in a reduction of computation time by a factor \\sim100 compared to a multi-fluid modelling approach. This implementation was combined with an LVG-based modelling of molecular line radiation transport. Using this model we calculated grids of shock models to explore the consequences of different dust-processing scenarios. Grain-...

  14. Estimate black hole masses of AGNs using ultraviolet emission line properties

    CERN Document Server

    Kong, M Z; Wang, R; Han, J L; Kong, Min-Zhi; Wu, Xue-Bing; Wang, Ran; Han, Jin-Lin

    2005-01-01

    Based on the measured sizes of broad line region of the reverberation-mapping AGN sample, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift ($z > 0.5$) AGNs. First, using the archival $IUE/HST$ spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical relations between the BLR size and \\Mg/\\C emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mapping sample for calibration, two new relationships for determination of black hole mass with the full width of half maximum and the luminosity of \\Mg/\\C line are also found. We then apply the relations to estimate the black hole masses of AGNs in Large Bright Quasar Surveyq and a sample of radio-loud quasars. For the objects with small radio-loudness, the black hole mass estimated using the $R_{\\rm BLR} - L_{\\eMg/\\eC}$ relation is consistent with that from the $R_{BLR} - L_{3000\\AA/1350 \\AA}$ relation. But for radio-...

  15. The Spectral Energy Distribution and Emission-Line properties of the NLS1 Galaxy Arakelian 564

    CERN Document Server

    Romano, P; Turner, T J; Krämer, S B; Crenshaw, D M; Peterson, B M; Pogge, R W; Brandt, W N; George, I M; Horne, K; Kriss, G A; Netzer, H; Shemmer, O; Wamsteker, W

    2004-01-01

    We present the intrinsic spectral energy distribution (SED) of the NLS1 Arakelian 564, constructed with contemporaneous data obtained during a multi-wavelength, multi-satellite observing campaign in 2000 and 2001. We compare it with that of the NLS1 Ton S180 and with those obtained for BLS1s to infer how the relative accretion rates vary among the Sy1 population. Although the peak of the SED is not well constrained, most of the energy is emitted in the 10-100 eV regime, constituting roughly half of the emitted energy in the optical/X-ray ranges. This is consistent with a primary spectral component peaking in the extreme UV/soft X-ray band, and disk-corona models, hence high accretion rates. Indeed, we estimate that \\dot{m}~1. We examine the emission lines in its spectrum, and we constrain the physical properties of the line-emitting gas through photoionization modeling. The line-emitting gas is characterized by log n~11 and log U~0, and is stratified around log U~0. Our estimate of the radius of the H\\beta-em...

  16. Multifrequency radiation hydrodynamics simulations of H2 line emission in primordial, star-forming clouds

    Science.gov (United States)

    Greif, Thomas H.

    2014-10-01

    We investigate the collapse of primordial gas in a minihalo with three-dimensional radiation hydrodynamics simulations that accurately model the transfer of H2 line emission. For this purpose, we have implemented a multiline, multifrequency ray-tracing scheme in the moving-mesh code AREPO that is capable of adaptively refining rays based on the HEALPIX algorithm, as well as a hybrid equilibrium/non-equilibrium primordial chemistry solver. We find that a multifrequency treatment of the individual H2 lines is essential, since for high optical depths the smaller cross-section in the wings of the lines greatly increases the amount of energy that can escape. The influence of Doppler shifts due to bulk velocities is comparatively small, since systematic velocity differences in the cloud are typically smaller than the sound speed. During the initial collapse phase, the radially averaged escape fraction agrees relatively well with the fit of Ripamonti & Abel. However, in general it is not advisable to use a simple density-dependent fitting function, since the escape fraction depends on many factors and does not capture the suppression of density perturbations due to the diffusion of radiation. The Sobolev method overestimates the escape fraction by more than an order of magnitude, since the properties of the gas change on scales smaller than the Sobolev length.

  17. Spectroscopic Studies of Solar Corona VI: Trend in Line-width Variation of Coronal Emission Lines with Height Independent of the Structure of Coronal Loops

    Indian Academy of Sciences (India)

    Jagdev Singh; Takashi Sakurai; Kiyoshi Ichimoto; S. Muneer

    2006-06-01

    We have obtained spectroscopic observations in coronal emission lines by choosing two lines simultaneously, one [Fe X] 6374 Å and the other [Fe XI] 7892 Å or [Fe XIII] 10747 Å or [Fe XIV] 5303 Å. We found that in 95 per cent of the coronal loops observed in 6374 Å, the FWHM of the emission line increases with height above the limb irrespective of the size, shape and orientation of the loop and that in case of 5303 Å line decreases with height in about 89 per cent of the coronal loops. The FWHM of 7892 Å and 10747 Å emission lines show intermediate behavior. The increase in the FWHM of 6374 Å line with height is the steepest among these four lines.We have also studied the intensity ratio and ratio of FWHM of these lines with respect to those of 6374 Å as a function height above the limb. We found that the intensity ratio of 7892 Å and 10747 Å lines with respect to 6374 Å line increases with height and that of 5303 Å to 6374 Å decreases with height above the limb. This implies that temperature in coronal loops will appear to increase with height in the intensity ratio plots of 7892 Å and 6374 Å; and 10747 Å and 6374 Å whereas it will appear to decrease with height in intensity ratio of 5303 Å to 6374 Å line versus height plot. These findings are up to a height of about 200 arcsec above the limb. The varying ratios with height indicate that relatively hotter and colder plasma in coronal loops interact with each other. Therefore, the observed increase in FWHM with height above the limb of coronal emission lines associated with plasma at about 1 MK may not be due to increase in non-thermal motions caused by coronal waves but due to interaction with the relatively hotter plasma. These findings also do not support the existing coronal loop models, which predict an increase in temperature of the loop with height above the limb.

  18. Halpha Emission Line Stars in M31, M33 and Seven Local Group Dwarfs

    Science.gov (United States)

    McNeill, Reagin T.; Massey, P.; Olsen, K. A.; Hodge, P. W.; Jacoby, G. H.; Blaha, C.; Smith, R. C.; Holmes, S. B.

    2006-12-01

    While there are many ideas as to how differing galactic environments affect the formation and evolution of massive stars, the numbers of stars with known physical properties outside the Milky Way are too scarce to provide much insight. For instance, we have a very poor idea as to the actual number of Luminous Blue Variables (LBVs) in nearby galaxies, since these have mostly been found on the basis of strong photometric variability over a span of a few decades. But, we know that the Galactic LBVs P Cygni and Eta Car had their last major photometric upsets centuries ago. Were these stars located in a nearby galaxy, we might well be unaware of them. In order to help rectify this situation, we have used the recent UBVRI catalogs of M31 and M33 (Massey et al. 2006) and seven dwarf galaxies in the Local Group (Massey et al. 2007) in conjunction with data from narrowband filters centered on Halpha, [SII] and [OIII] to select Halpha emission sources with similar characteristics to the known LBVs. This search uncovered over 300 potential Halpha emission sources in M31 and M33, and 41 potential Halpha emission sources in the dwarf galaxies. Many of the most promising objects in M31 and M33 were observed spectroscopically at WIYN in September, revealing a wealth of new LBVs and Wolf-Rayet stars. In our poster we will outline our selection method and show some of the newly found emission-lined stars. Funding provided by the NSF through grant number AST-0453611.

  19. NLTE carbon abundance determination in selected A- and B-type stars and the interpretation of C I emission lines

    Science.gov (United States)

    Alexeeva, S. A.; Ryabchikova, T. A.; Mashonkina, L. I.

    2016-10-01

    We constructed a comprehensive model atom for C I-C II using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for C I and C II in classical 1D models representing the atmospheres of A- and late B-type stars. Our NLTE calculations predict the emission that appears at effective temperature of 9250 to 10 500 K depending on log g in the C I 8335, 9405 Å singlet lines and at Teff> 15 000 K (log g = 4) in the C I 9061-9111 Å, 9603-9658 Å triplet lines. A pre-requisite of the emission phenomenon is the overionization-recombination mechanism resulting in a depopulation of the lower levels of C I to a greater extent than the upper levels. Extra depopulation of the lower levels of the transitions corresponding to the near-infrared lines, is caused by photon loss in the UV lines C I 2479, 1930, and 1657 Å. We analysed the lines of C I and C II in Vega, HD 73666, Sirius, 21 Peg, π Cet, HD 22136, and ι Her taking advantage of their observed high-resolution spectra. The C I emission lines were detected in the four hottest stars, and they were well reproduced in our NLTE calculations. For each star, the mean NLTE abundances from lines of the two ionization stages, C I and C II, including the C I emission lines, were found to be consistent. We show that the predicted C I emission phenomenon depends strongly on whether accurate or approximate electron-impact excitation rates are applied.

  20. A dynamical magnetosphere model for periodic Halpha emission from the slowly rotating magnetic O star HD191612

    CERN Document Server

    Sundqvist, Jon O; Owocki, Stanley P; Townsend, Richard H D; Howarth, Ian D; Wade, Gregg A

    2012-01-01

    The magnetic O-star HD191612 exhibits strongly variable, cyclic Balmer line emission on a 538-day period. We show here that its variable Halpha emission can be well reproduced by the rotational phase variation of synthetic spectra computed directly from full radiation magneto-hydrodynamical simulations of a magnetically confined wind. In slow rotators such as HD191612, wind material on closed magnetic field loops falls back to the star, but the transient suspension of material within the loops leads to a statistically overdense, low velocity region around the magnetic equator, causing the spectral variations. We contrast such "dynamical magnetospheres" (DMs) with the more steady-state "centrifugal magnetospheres" of stars with rapid rotation, and discuss the prospects of using this DM paradigm to explain periodic line emission from also other non-rapidly rotating magnetic massive stars.

  1. Determination of nitrogen to carbon abundance ratios from transition layer emission lines

    Science.gov (United States)

    Boehm-Vitense, Erika

    1992-01-01

    We have finished studying the nitrogen to carbon abundance ratios for stars with different effective temperatures T(sub eff) and luminosities using transition layer emission lines and using spectra available in the IUE archives. The N/C abundance ratio determinations using transition layer emission lines are as accurate as the photospheric abundance determinations as found by comparison of results obtained by both methods for the same stars. Our measurements confirm photospheric abundance determinations in regions of the HR diagram where they can be obtained. Our studies have extended the temperature range to higher temperatures. They have shown the exact positions in the HR diagram where the mixing due to the outer convection zones reaches deep enough to bring nuclear processed material to the surface. This occurs at effective temperatures which are higher by delta log T(sub eff) approximately 0.04 or roughly 400 K than expected theoretically. Since the depth of the convection zone increases rapidly with decreasing T(sub eff) this may indicate considerable overshoot beyond the lower boundary of the convection zone. Our N/C abundance ratio determinations from transition layer emission lines have confirmed that the actual enrichment observed for some cool giants is larger than expected theoretically, again indicating a larger degree of mixing in several stars either from below or from above. For the supergiants it probably indicates overshoot above the convective core in the progenitor main sequence stars. For the more massive giants this may also be the case, though we did not find a correlation between delta log N/C and the absolute magnitudes, but these are rather uncertain. As byproducts of these studies we also found anomalies in Si/C and N/C abundance ratios for F giants which can be understood as the relict of surface abundance changes for their main sequence progenitors due to diffusion. This anomaly disappears for G giants, for which the depths of the

  2. Mid-Infrared [NeII] and [NeIII] Emission Line Profiles in Starbursts and AGN

    Science.gov (United States)

    Samsonyan, A. L.

    2016-09-01

    Line profiles and velocities of the [CII] 157μm line observed with the Herschel PACS instrument are compared to high resolution [NeII] 12.81μm and [NeIII] 15.55μm emission lines observed with the Spitzer Infrared Spectrograph (IRS). We are analysing spectra of at least 400 galaxies having both IRS high resolution and Herschel PACS [CII] line profiles that are available from the public archives. The goal of the work is the comparison of emission line velocity profiles and fluxes to locate and understand differences in the origins of [CII] compared to the mid-infrared Neon lines. Line velocities and widths are carefully measured, and errors are analyzed to determine if there is any kinematic evidence for [CII] arising from clouds not visible in the mid-infrared emission lines. This will give an answer to two questions: 1. Is there evidence that [CII] is more diffuse, distributed throughout galaxies, than the mid infrared starburst indicators [NeII] and [NeIII]?; 2. Is there evidence for specific, very dusty clouds of [CII] with so much extinction that the [CII] can be seen but the [NeII] and [NeIII] is not seen?

  3. X-ray emission line spectroscopy of cataclysmic variables. II. Temperatures and densities from line ratios in the Chandra HETG band

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, E. M.; Shipley, H. V. [Department of Physics and Astronomy, University of Texas-San Antonio, San Antonio, TX 78249 (United States); Rana, V. R. [Space Radiation Laboratory, Caltech, Pasadena, CA 91125 (United States); Barrett, P. E. [US Naval Observatory, Washington, DC 20392-5420 (United States); Singh, K. P., E-mail: eric.schlegel@utsa.edu, E-mail: vrana@srl.caltech.edu, E-mail: barrett.paul@usno.navy.mil, E-mail: singh@tifr.res.in [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai (India)

    2014-12-10

    We summarize the results of a line-by-line fitting analysis of the available spectra obtained using the Chandra High-Energy Transmission Grating. We confirm the existence of broad ionization and electron temperature ranges and high number densities in cataclysmic variables (CVs) of all subtypes. Temperatures range from ∼0.4 keV to ∼5-10 keV or more with a broad range detected in any given CV. In other words, single-temperature models do not describe the line emission. Number densities also cover a broad range, from 10{sup 12} to >10{sup 16} cm{sup –3}. We demonstrate that much of the plasma is in a nonequilibrium state; the Fe emission, however, may arise from plasma in the ionization equilibrium.

  4. X-ray emission line spectroscopy of cataclysmic variables. II. Temperatures and densities from line ratios in the Chandra HETG band

    International Nuclear Information System (INIS)

    We summarize the results of a line-by-line fitting analysis of the available spectra obtained using the Chandra High-Energy Transmission Grating. We confirm the existence of broad ionization and electron temperature ranges and high number densities in cataclysmic variables (CVs) of all subtypes. Temperatures range from ∼0.4 keV to ∼5-10 keV or more with a broad range detected in any given CV. In other words, single-temperature models do not describe the line emission. Number densities also cover a broad range, from 1012 to >1016 cm–3. We demonstrate that much of the plasma is in a nonequilibrium state; the Fe emission, however, may arise from plasma in the ionization equilibrium.

  5. Resolving the optical emission lines of Lya blob 'B1' at z=2.38: another hidden quasar

    CERN Document Server

    Overzier, R A; Dijkstra, M; Hatch, N A; Lehnert, M D; Villar-Martín, M; Wilman, R J; Zirm, A W

    2013-01-01

    We have used the SINFONI near-infrared integral field unit on the VLT to resolve the optical emission line structure of one of the brightest (L~1e44 erg/s) and nearest (z=2.38) of all Lya blobs (LABs). The target, known in the literature as object 'B1' (Francis et al. 1996), lies at a redshift where the main optical emission lines are accessible in the observed near-infrared. We detect luminous [OIII]4959,5007A and Ha emission with a spatial extent of at least 32x40 kpc (4"x5"). The dominant optical emission line component shows relatively broad lines (600-800 km/s, FWHM) and line ratios consistent with AGN-photoionization. The new evidence for AGN photoionization, combined with previously detected CIV and luminous, warm infrared emission, suggest that B1 is the site of a hidden quasar. This is confirmed by the fact that [OII] is relatively weak compared to [OIII] (extinction-corrected [OIII]/[OII] of about 3.8), which is indicative of a high, Seyfert-like ionization parameter. From the [OIII] luminosity we i...

  6. Exploring star formation in high-z galaxies using atomic and molecular emission lines

    Science.gov (United States)

    Gullberg, Bitten

    2016-03-01

    The conditions under which stars are formed and the reasons for triggering and quenching of starburst events in high-z galaxies, are still not well understood. Studying the interstellar medium (ISM) and the morphology of high-z galaxies are therefore key points in order to understand galaxy evolution. The cosmic star formation rate density peaks between 1Universe is therefore crucial to investigate in order to know more about the star-formation triggering and quenching mechanisms. Phenomena such as major mergers and galactic nuclear activity are believed to be mechanisms dominating the star formation activity at this period of time. It is therefore necessary to study galaxy populations which show signs of major merger events and active galactic nuclei (AGN). This thesis presents three studies of the ISM in high-z galaxies and their morphologies by: Exploring the physical conditions of the ISM in a sample of dusty star-forming galaxies (DSFGs) using the relative observed line strength of ionised carbon ([CII]) and carbon monoxide (CO). We find that the line ratios can best be described by a medium of [CII] and CO emitting gas with a higher [CII] than CO excitation temperature, high CO optical depth tau(CO)>>1, and low to moderate [CII] optical depth tau(CII)water (H2O) and an unusually large amount of neutral atomic carbon ([CI]) relative to highly excited CO compared to lensed DSFGs. The detection of water (H2O) emission, which is not associated with the 246GHz continuum emission, suggests excitation by shocks. The uncommon line ratio between [CI]2-1 and CO(7-6) might be due special conditions of the ISM in MRC1138-262 dominated by cosmic rays or differential lensing in other DSFGs thereby not representing the intrinsic ratio. These three studies of the physical conditions of the ISM and morphology of high-z galaxies at z>2, pave the road for future investigations of the star-forming ISM in high-z galaxies, by illustrating the importance of multi-wavelength, fine

  7. Electron density profile measurements from hydrogen line intensity ratio method in Versatile Experiment Spherical Torus

    Science.gov (United States)

    Kim, YooSung; Shi, Yue-Jiang; Yang, Jeong-hun; Kim, SeongCheol; Kim, Young-Gi; Dang, Jeong-Jeung; Yang, Seongmoo; Jo, Jungmin; Oh, Soo-Ghee; Chung, Kyoung-Jae; Hwang, Y. S.

    2016-11-01

    Electron density profiles of versatile experiment spherical torus plasmas are measured by using a hydrogen line intensity ratio method. A fast-frame visible camera with appropriate bandpass filters is used to detect images of Balmer line intensities. The unique optical system makes it possible to take images of Hα and Hβ radiation simultaneously, with only one camera. The frame rate is 1000 fps and the spatial resolution of the system is about 0.5 cm. One-dimensional local emissivity profiles have been obtained from the toroidal line of sight with viewing dumps. An initial result for the electron density profile is presented and is in reasonable agreement with values measured by a triple Langmuir probe.

  8. Modeling the Line-of-Sight Integrated Emission in the Corona: Implications for Coronal Heating

    CERN Document Server

    Viall, Nicholeen M

    2013-01-01

    One of the outstanding problems in all of space science is uncovering how the solar corona is heated to temperatures greater than 1 MK. Though studied for decades, one of the major difficulties in solving this problem has been unraveling the line-of-sight (LOS) effects in the observations. The corona is optically thin, so a single pixel measures counts from an indeterminate number (perhaps tens of thousands) of independently heated flux tubes, all along that pixel's LOS. In this paper we model the emission in individual pixels imaging the active region corona in the Extreme Ultraviolet. If LOS effects are not properly taken into account, erroneous conclusions regarding both coronal heating and coronal dynamics may be reached. We model the corona as a LOS integration of many thousands of completely independently heated flux tubes. We demonstrate that despite the superposition of randomly heated flux tubes, nanoflares leave distinct signatures in light curves observed with multi-wavelength and high time cadence...

  9. A Search for Low Surface Brightness Structure Around Compact Narrow Emission Line Galaxies

    CERN Document Server

    Barton, E J; Bershady, M A; Barton, Elizabeth J.; Zee, Liese van; Bershady, Matthew A.

    2006-01-01

    As the most extreme members of the rapidly evolving faint blue galaxy population at intermediate redshift, the compact narrow emission line galaxies (CNELGs) are intrinsically luminous (-22 -18). Conversely, 15 are not blue enough to fade to low-luminosity dwarfs (M_B > -15.2). The majority of the CNELGs are consistent with progenitors of intermediate-luminosity dwarfs and low-luminosity spiral galaxies with small disks. CNELGs are a heterogeneous progenitor population with significant fractions (up to 44%) capable of fading into today's faint dwarfs (M_B > -15.2), while 15 to 85% may only experience an apparently extremely compact CNELG phase at intermediate redshift but remain more luminous galaxies at the present epoch.

  10. FeII/MgII Emission Line Ratio in High Redshift Quasars

    DEFF Research Database (Denmark)

    Dietrich, M.; Hamann, F.; Appenzeller, I.;

    2003-01-01

    We present results of the analysis of near infrared spectroscopic observations of 6 high-redshift quasars (z > 4), emphasizing the measurement of the ultraviolet FeII/MgII emission line strength in order to estimate the beginning of intense star formation in the early universe. To investigate the...... evolution of the FeII/MgII ratio over a wider range in cosmic time, we measured this ratio for composite quasar spectra which cover a redshift range of 0 4 quasars must have started already at an epoch corresponding to z_f = 6 to 9, when the age of the universe was ~0.5 Gyr (H_o = 72 km/s/Mpc, Omega_M = 0...

  11. Magnetically elevated accretion disks in active galactic nuclei: broad emission line regions and associated star formation

    CERN Document Server

    Begelman, Mitchell C

    2016-01-01

    We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal ($\\phi-$direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at $R$ to large heights $z > 0.1 R$ and low densities, while leaving a thin dense layer containing most of the mass --- but contributing very little accretion --- around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: th...

  12. The Covering Factor of Warm Dust in Weak Emission-Line Active Galactic Nuclei

    CERN Document Server

    Zhang, Xudong

    2016-01-01

    Weak emission-line active galactic nuclei (WLAGNs) are radio-quiet active galactic nuclei (AGNs) that have nearly featureless optical spectra. We investigate the ultraviolet to mid-infrared spectral energy distributions of 73 WLAGNs (0.4

  13. Properties of the radio jet emission of four gamma-ray Narrow Line Seyfert 1 galaxies

    CERN Document Server

    Angelakis, E; Myserlis, I; Nestoras, I; Karamanavis, V; Krichbaum, T P; Zensus, J A; Marchili, N; Foschini, L; Ungerechts, H; Sievers, A

    2013-01-01

    The detection of gamma rays from a small number of Narrow Line Seyfert 1 galaxies by the LAT instrument onboard Fermi seriously challenged our understanding of AGN physics. Among the most important findings associated with their discovery has been the realisation that smaller-mass black holes seem to be hosted by these systems. Immediately after their discovery a radio multi- frequency monitoring campaign was initiated to understand their jet radio emission. Here the first results of the campaign are presented. The light curves and some first variability analyses are discussed, showing that the brightness temperatures and Doppler factors are moderate. The phenomenologies are typically blazar-like. The frequency domain on the other hand indicates intense spectral evolution and the variability patterns indicate mechanisms similar to those acting in the jets of BL Lacs and FSRQs. Finally, the linear polarisation also reveals the presence of a quiescent, optically thin jet in certain cases.

  14. Deep observations of CO line emission from star-forming galaxies in a cluster candidate at z=1.5

    CERN Document Server

    Aravena, M; Salvato, M; Tanaka, M; Lentati, L; Schinnerer, E; Walter, F; Riechers, D; Smolcic, V; Capak, P; Aussel, H; Bertoldi, F; Chapman, S C; Farrah, D; Finoguenov, A; Floc'h, E Le; Lutz, D; Magdis, G; Oliver, S; Riguccini, L; Berta, S; Magnelli, B; Pozzi, F

    2012-01-01

    We report results from a deep Jansky Very Large Array (JVLA) search for CO 1-0 line emission from galaxies in a candidate galaxy cluster at z~1.55 in the COSMOS field. We target 4 galaxies with optical spectroscopic redshifts in the range z=1.47-1.59. Two of these 4 galaxies, ID51613 and ID51813, are nominally detected in CO line emission at the 3-4 sigma level. We find CO luminosities of 2.4x10^10 K km/s pc^2 and 1.3x10^10 K km/s pc^2, respectively. Taking advantage from the clustering and 2-GHz bandwidth of the JVLA, we perform a search for emission lines in the proximity of optical sources within the field of view of our observations. We limit our search to galaxies with K4 sigma) in the data cube, which we identify with the CO line emission. To test the reliability of the line peaks found, we performed a parallel search for line peaks using a Bayesian inference method. Monte Carlo simulations show that such associations are statistically significant, with probabilities of chance association of 3.5% and 10...

  15. Photometric redshifts and clustering of emission line galaxies selected jointly by DES and eBOSS

    Energy Technology Data Exchange (ETDEWEB)

    Jouvel, S.; et al.

    2015-09-23

    We present the results of the first test plates of the extended Baryon Oscillation Spectroscopic Survey. This paper focuses on the emission line galaxies (ELG) population targetted from the Dark Energy Survey (DES) photometry. We analyse the success rate, efficiency, redshift distribution, and clustering properties of the targets. From the 9000 spectroscopic redshifts targetted, 4600 have been selected from the DES photometry. The total success rate for redshifts between 0.6 and 1.2 is 71\\% and 68\\% respectively for a bright and faint, on average more distant, samples including redshifts measured from a single strong emission line. We find a mean redshift of 0.8 and 0.87, with 15 and 13\\% of unknown redshifts respectively for the bright and faint samples. In the redshift range 0.6

  16. WIDE-FIELD SURVEY OF EMISSION-LINE STARS IN IC 1396

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, M. [Faculty of Education and Welfare Science, Oita University, Oita 870-1192 (Japan); Sugitani, K. [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan); Watanabe, M. [Department of Cosmosciences, Hokkaido University, Sapporo 060-0810 (Japan); Fukuda, N. [Department of Computer Simulation, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005 (Japan); Ishihara, D. [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Ueno, M., E-mail: mnakano@oita-u.ac.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshino-dai, Chuo-ku, Sagamihara 252-5210 (Japan)

    2012-03-15

    We have made an extensive survey of emission-line stars in the IC 1396 H II region to investigate the low-mass population of pre-main-sequence (PMS) stars. A total of 639 H{alpha} emission-line stars were detected in an area of 4.2 deg{sup 2} and their i' photometry was measured. Their spatial distribution exhibits several aggregates near the elephant trunk globule (Rim A) and bright-rimmed clouds at the edge of the H II region (Rim B and SFO 37, 38, 39, 41), and near HD 206267, which is the main exciting star of the H II region. Based on the extinction estimated from the near-infrared color-color diagram, we have selected PMS star candidates associated with IC 1396. The age and mass were derived from the extinction-corrected color-magnitude diagram and theoretical PMS tracks. Most of our PMS candidates have ages of <3 Myr and masses of 0.2-0.6 M{sub Sun }. Although it appears that only a few stars were formed in the last 1 Myr in the east region of the exciting star, the age difference among subregions in our surveyed area is not clear from the statistical test. Our results may suggest that massive stars were born after the continuous formation of low-mass stars for 10 Myr. The birth of the exciting star could be the late stage of slow but contiguous star formation in the natal molecular cloud. It may have triggered the formation of many low-mass stars at the dense inhomogeneity in and around the H II region by a radiation-driven implosion.

  17. Uncovering the Spectral Energy Distribution in Active Galaxies Using High Ionization Mid-Infrared Emission Lines

    Science.gov (United States)

    Melendez, M.; Kraemer, S. B.; Weaver, K. A.; Mushotzky, R. F.

    2011-01-01

    The shape of the spectral energy distribution of active galaxies in the EUV soft X-ray band (13.6 eV to 1 keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the spectral energy distribution in this energy band, we have generated a set of photoionization models which reproduce the small dispersion found in correlations between high-ionization mid-infrared emission lines in a sample of hard X-ray selected AGN. Our calculations show that a broken power-law continuum model is sufficient to reproduce the [Ne V]14.32 microns/[Ne III], [Ne V]24.32 microns/[O IV]25.89 micron and [O IV] 25.89 microns/[Ne III] ratios, and does not require the addition of a "big bump" EUV model component. We constrain the EUV-soft X-ray slope, alpha(sub i), to be between 1.5 - 2.0 and derive a best fit of alpha(sub i) approx. 1.9 for Seyfert 1 galaxies, consistent with previous studies of intermediate redshift quasars. If we assume a blue bump model, most sources in our sample have derived temperatures between T(sub BB) = 10(exp 5.18) K to 10(exp 5.7) K, suggesting that the peak of this component spans a large range of energies extending from approx. (Lambda)600 A to > (Lambda)1900 A. In this case, the best fitting peak energy that matches the mid-infrared line ratios of Seyfert 1 galaxies occurs between approx. (Lambda)700-(Lambda)1000 A. Despite the fact that our results do not rule out the presence of an EUV bump, we conclude that our power-law model produces enough photons with energies > 4 Ry to generate the observed amount of mid-infrared emission in our sample of BAT AGN.

  18. [C II] LINE EMISSION IN MASSIVE STAR-FORMING GALAXIES AT z = 4.7

    International Nuclear Information System (INIS)

    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C II] 157.7 μm fine structure line and thermal dust continuum emission from a pair of gas-rich galaxies at z = 4.7, BR1202-0725. This system consists of a luminous quasar host galaxy and a bright submillimeter galaxy (SMG), while a fainter star-forming galaxy is also spatially coincident within a 4'' (25 kpc) region. All three galaxies are detected in the submillimeter continuum, indicating FIR luminosities in excess of 1013 L☉ for the two most luminous objects. The SMG and the quasar host galaxy are both detected in [C II] line emission with luminosities L[CII] = (10.0 ± 1.5) × 109 L☉ and L[CII] = (6.5 ± 1.0) × 109 L☉, respectively. We estimate a luminosity ratio L[CII]/LFIR = (8.3 ± 1.2) × 10–4 for the starburst SMG to the north and L[CII]/LFIR = (2.5 ± 0.4) × 10–4 for the quasar host galaxy, in agreement with previous high-redshift studies that suggest lower [C II]-to-FIR luminosity ratios in quasars than in starburst galaxies. The third fainter object with a flux density S340GHz = 1.9 ± 0.3 mJy is coincident with a Lyα emitter and is detected in HST ACS F775W and F814W images but has no clear counterpart in the H band. Even if this third companion does not lie at a redshift similar to BR1202-0725, the quasar and the SMG represent an overdensity of massive, infrared luminous star-forming galaxies within 1.3 Gyr of the big bang.

  19. Survey for Emission-Line Galaxies Universidad Complutense de Madrid List 3

    CERN Document Server

    Alonso, O; Zamorano, J; Gallego, J M; Rego, M

    1999-01-01

    A new low-dispersion objective-prism search for low-redshift (z<0.045) emission-line galaxies (ELG) has been carried out by the Universidad Complutense de Madrid with the Schmidt Telescope at the Calar-Alto Observatory. This is a continuation of the UCM Survey, which was performed by visual selection of candidates in photographic plates via the presence of the Halpha+[NII]6584 blend in emission. In this new list we have applied an automatic procedure, fully developed by us, for selecting and analyzing the ELG candidates on the digitized images obtained with the MAMA machine. The analyzed region of the sky covers 189 square degrees in nine fields near R.A.=14h & 17h, Dec=25 deg. The final sample contains 113 candidates. Special effort has been made to obtain a large amount of information directly from our uncalibrated plates by using several external calibrations. The parameters obtained for the ELG candidates allow for the study of the statistical properties for the sample.

  20. Radio continuum detection in blue early-type weak-emission-line galaxies

    Science.gov (United States)

    Paswan, A.; Omar, A.

    2016-06-01

    The star formation rates (SFRs) in weak-emission-line (WEL) galaxies in a volume-limited (0.02 Hz-1, respectively. The radio far-infrared correlation in four WEL galaxies suggests that the radio continuum emission from WEL galaxies is most likely a result of star formation activities. The median SFR for WEL galaxies is estimated as 0.23 ± 0.06 M⊙ yr-1, which is much less than SFRs (0.5-50 M⊙ yr-1) in purely star-forming blue ETGs. The SFRs in blue ETGs are found to be correlated with their stellar velocity dispersions (σ) and decreasing gradually beyond σ of ˜100 km s-1. This effect is most likely linked to the growth of a black hole and the suppression of star formation via active galactic nucleus (AGN) feedback. The colour differences between star-forming and WEL subtypes of blue ETGs appear to be driven to a large extent by the level of current star formation activities. In a likely scenario of an evolutionary sequence between subtypes, the observed colour distribution in blue ETGs can be explained best in terms of fast evolution through AGN feedback.

  1. The evolution of Balmer jump selected galaxies in the ALHAMBRA survey

    CERN Document Server

    Iribarren, P Troncoso; Padilla, N; Lacerna, I; Garcia, S; Orsi, A; Arancibia, A Muñoz; Moustakas, J; Cristóbal-Hornillos, J; Moles, M; Fernández-Soto, A; Martínez, V J; Cerviño, M; Alfaro, E J; Ascaso, B; Arnalte-Mur, P; Nieves-Seoane, L; Benítez, N

    2016-01-01

    We present a new color-selection technique, based on the Bruzual & Charlot models convolved with the bands of the ALHAMBRA survey, and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 < z < 1.5. These galaxies are dubbed Balmer jump Galaxies BJGs. We apply the iSEDfit Bayesian approach to fit each detailed SED and determine star-formation rate (SFR), stellar mass, age and absolute magnitudes. The mass of the haloes where these samples reside are found via a clustering analysis. Five volume-limited BJG sub-samples with different mean redshifts are found to reside in haloes of median masses $\\sim 10^{12.5 \\pm 0.2} M_\\odot$ slightly increasing toward z=0.5. This increment is similar to numerical simulations results which suggests that we are tracing the evolution of an evolving population of haloes as they grow to reach a mass of $\\sim 10^{12.7 \\pm 0.1} M_\\odot$ at z=0.5. The likely progenitors of our samples at z$\\sim$3 are Lyman Break Galaxies, whic...

  2. Iron Fluorescent Line Emission from the mCvs and Hard X-ray Emitting Symbiotic Stars as a Source of the Iron Fluorescent Line Emission from the Galactic Ridge

    CERN Document Server

    Romanus, Eze; Ebisawa, Ken

    2015-01-01

    The Galactic Ridge X-ray Emission (GRXE) spectrum has strong iron emission lines at 6.4, 6.7, and 7.0~keV, each corresponding to the neutral (or low-ionized), He-like, and H-like iron ions. The 6.4~keV fluorescence line is due to irradiation of neutral (or low ionized) material (iron) by hard X-ray sources, indicating uniform presence of the cold matter in the Galactic plane. In order to resolve origin of the cold fluorescent matter, we examined the contribution of the 6.4~keV line emission from white dwarf surfaces in the hard X-ray emitting symbiotic stars (hSSs) and magnetic cataclysmic variables (mCVs) to the GRXE. In our spectral analysis of 4~hSSs and 19~mCVs observed with Suzaku, we were able to resolve the three iron emission lines. We found that the equivalent-widths (EWs) of the 6.4~keV lines of hSSs are systematically higher than those of mCVs, such that the average EWs of hSSs and mCVs are $179_{-11}^{+46}$~eV and $93_{-3}^{+20}$~eV, respectively. The EW of hSSs compares favorably with the typical...

  3. Optimization of soft x-ray line emission from laser-produced carbon plasma with laser intensity

    Indian Academy of Sciences (India)

    A Chowdhury; R A Joshi; G P Gupta; P A Naik; P D Gupta

    2003-12-01

    Absolute measurement for He- resonance (1s2 10-1s2p 11, at 40.2 Å) line emission from a laser-produced carbon plasma has been studied as a function of laser intensity. The optimum laser intensity is found to be ≈ 1.3 × 1012 W/cm2 for the maximum emission of 3.2 × 1013 photons sr-1 pulse-1. Since this line lies in the water window spectral region, it has potential application in x-ray microscopic imaging of biological sample in wet condition. Theoretical calculation using corona model for the emission of this line is also carried out with appropriate ionization and radiative recombination rate coefficients.

  4. Be phenomenon in open clusters: Results from a survey of emission-line stars in young open clusters

    CERN Document Server

    Mathew, Blesson; Bhatt, Bhuwan Chandra

    2008-01-01

    Emission-line stars in young open clusters are identified to study their properties, as a function of age, spectral type and their evolutionary state. 207 open star clusters were observed using slitless spectroscopy method and 157 emission stars were identified in 42 clusters. We have found 54 new emission-line stars in 24 open clusters, out of which 19 clusters are found to house emission stars for the first time. About 20% clusters harbour emission stars. The fraction of clusters housing emission stars is maximum in both the 0--10 and 20--30 Myr age bin ($\\sim$ 40% each) and in the other age bins, this fraction ranges between 10% -- 25%, upto 80 Myr. We have used optical colour magnitude diagram (CMD) along with Near-IR Colour-Colour diagram (NIR CCDm) to classify the emission stars into Classical Be (CBe) stars and Herbig Be (HBe) stars. Most of the emission stars in our survey belong to CBe class ($\\sim$ 92%) while a few are HBe stars ($\\sim$ 6%) and HAe stars ($\\sim$1%). The CBe stars are located all alo...

  5. Inversion technique to obtain an emissivity profile from tangential line-integrated hard x-ray measurements

    International Nuclear Information System (INIS)

    A matrix inversion technique has been developed to calculate local x-ray emissivity profiles from line-integrated x-ray measurements from an anisotropic source. A 2D hard x-ray camera has been used to measure tangential line-integrated bremsstrahlung emission from suprathermal electrons generated by lower hybrid current drive in the PBX-M tokamak. Local emissivities, E, on the midplane of the tokamak are useful to localize the lower hybrid-driven current. The anisotropy is assumed to be uniform over the plasma with a form E(R,θ)=E(R)cosn(θ), where E(R) is the forward emissivity at the major radius R, θ is the angle to the camera from tangency, and the exponent n defines the degree of anisotropy. For isotropic emission, n=0. The measured brightness B(R) on the midplane is then related to the forward emissivity E(R) by a matrix M=L(R,φ)cosn[θ(R,φ)], where φ is the toroidal angle, L is a length matrix containing the path lengths through the plasma. By inverting the matrix M, the forward emissivity is obtained from the measured brightness, E=M-1B. The anisotropy exponent n is adjusted to match the emission at the inner and outer radii of the plasma

  6. The ALMA detection of CO rotational line emission in AGB stars in the Large Magellanic Cloud

    CERN Document Server

    Groenewegen, M A T; Marigo, P; Sloan, G C; Decin, L; Feast, M W; Goldman, S R; Justtanont, K; Kerschbaum, F; Matsuura, M; McDonald, I; Olofsson, H; Sahai, R; van Loon, J Th; Wood, P R; Zijlstra, A A; Bernard-Salas, J; Boyer, M L; Guzman-Ramirez, L; Jones, O C; Lagadec, E; Meixner, M; Rawlings, M G; Srinivasan, S

    2016-01-01

    Context: Low- and intermediate-mass stars lose most of their stellar mass at the end of their lives on the asymptotic giant branch (AGB). Determining gas and dust mass-loss rates (MLRs) is important in quantifying the contribution of evolved stars to the enrichment of the interstellar medium. Aims: Attempt to, for the first time, spectrally resolve CO thermal line emission in a small sample of AGB stars in the Large Magellanic Cloud. Methods: ALMA was used to observe 2 OH/IR stars and 4 carbon stars in the LMC in the CO J= 2-1 line. Results: We present the first measurement of expansion velocities in extragalactic carbon stars. All four C-stars are detected and wind expansion velocities and stellar velocities are directly measured. Mass-loss rates are derived from modelling the spectral energy distribution and Spitzer/IRS spectrum with the DUSTY code. Gas-to-dust ratios are derived that make the predicted velocities agree with the observed ones. The expansion velocities and MLRs are compared to a Galactic sam...

  7. Comparisons of Infrared Colors and Emission-line Intensities between Two types of Seyfert 2 Galaxies

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We study the relation between the infrared colors, [OIII] emission lines, gaseous absorbing column density (NH),and the detectability of the polarized (hidden) broad-line region (HBLR) in a large sample of 75 Seyfert 2 galaxies (Sy2s).From the indicators of star-formation activity, f60/f100 and LFIR/LB, we find some evidence that the Sy2s without HBLR show higher star-formation activities than those with HBLR, in agreement with previous prediction. Also, we confirm that theHBLR Sy2s tend to have a larger luminosity ratio of the core to the host galaxy,suggesting that the HBLR Sy2s display more powerful AGN activity. However, the level of obscuration found in previous papers is nearly indistinguishable between the two types of Sy2s. The results support the statement that the non-HBLR Sy2s,with a weaker core component and a stronger star-formation activity component,are intrinsically different from the HBLR Sy2s, which are Sy1 systems with a hidden powerful AGN core and a low star-formation activity. The indications are that the non-HBLR Sy2s might be at an earlier evolutionary phase than the HBLR Sy2s.

  8. Estimating Black Hole Masses in Quasars Using Broad Optical and UV Emission Lines

    CERN Document Server

    Marziani, Paola

    2011-01-01

    We review past work using broad emission lines as virial estimators of black hole masses in quasars. Basically one requires estimates of the emitting region radius and virial velocity dispersion to obtain black hole masses. The three major ways to estimate the broad-line emitting region (BLR) radius involve: (1) direct reverberation mapping, (2) derivation of BLR radius for larger samples using the radius-luminosity correlation derived from reverberation measures, and (3) estimates of BLR radius using the definition of the ionization parameter solved for BLR radius (photoionization method). At low redshift (z < 0.7) FWHM H-beta serves as the most widely used estimator of virial velocity dispersion. FWHM H-beta can provide estimates for tens of thousands of quasars out to z ~ 3.8 (IR spectroscopy beyond z ~ 1). A new photoionization method also shows promise for providing many reasonable estimates of BLR radius via high S/N IR spectroscopy of the UV region 1300 -- 2000 A. FWHM MgII 2800 can serve as a surro...

  9. Quantitative analysis of resolved X-ray emission line profiles of O stars

    CERN Document Server

    Cohen, David H; Townsend, Richard H D

    2007-01-01

    By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of $\\zeta$ Pup, we are able to explore the trade-offs between reduced mass-loss rates and wind porosity. We find that reducing the mass-loss rate of $\\zeta$ Pup by roughly a factor of four, to 1.5 \\times 10^{-6} M_sun/yr, enables simple non-porous wind models to provide good fits to the data. If, on the other hand, we take the literature mass-loss rate of 6 \\times 10^{-6} M_sun/yr, then to produce X-ray line profiles that fit the data, extreme porosity lengths -- of $h_{\\infty} \\approx 3$ Rstar -- are required. Moreover, these porous models do not provide better fits to the data than the non-porous, low optical depth models. Additionally, such huge porosity lengths do not seem realistic in light of 2-D numerical simulations of the wind instability.

  10. Detailed Characterization of H_beta emission line profile in low z SDSS quasars

    CERN Document Server

    Zamfir, S; Marziani, P; Dultzin, D

    2009-01-01

    We explore the properties of the H_beta emission line profile in a large, homogeneous and bright sample of N~470 low redshift quasars extracted from Sloan Digital Sky Survey (DR5). We approach the investigation from two complementary directions: composite/median spectra and a set of line diagnostic measures (asymmetry index, centroid shift and kurtosis) in individual quasars. The project is developed and presented in the framework of the so-called 4D Eigenvector 1 (4DE1) Parameter Space, with a focus on its optical dimensions, FWHM(H_beta) and the relative strength of optical FeII (R_FeII=W(FeII4434-4684)/W(H_beta)). We reenforce the conclusion that not all quasars are alike and spectroscopically they do not distribute randomly about an average typical optical spectrum. Our results give further support to the concept of two populations A and B (narrower and broader than 4000 km/s FWHM(H_beta), respectively) that emerged in the context of 4DE1 space. The broad H_beta profiles in composite spectra of Population...

  11. Method for evaluating chemical shifts of x-ray emission lines in molecules and solids

    Science.gov (United States)

    Lomachuk, Yuriy V.; Titov, Anatoly V.

    2013-12-01

    A method of evaluating chemical shifts of x-ray emission lines for period four and heavier elements is developed. This method is based on the relativistic pseudopotential model and one-center restoration approach [Int. J. Quantum Chem.IJQCB20020-760810.1002/qua.20418 104, 223 (2005)] to recover a proper electronic structure in heavy-atom cores after the pseudopotential simulation of chemical compounds. The approximations of instantaneous transition and frozen core are presently applied to derive an expression for chemical shift as a difference between mean values of certain effective operator. The method allows one to avoid evaluation of small quantities (chemical shifts ˜0.01-1 eV) as differences of very large values (transition energies ˜1-100 keV in various compounds). The results of our calculations of chemical shifts for the Kα1, Kα2, and L transitions of group-14 metal cations with respect to neutral atoms are presented. Calculations of Kα1-line chemical shifts for the Pb core transitions in PbO and PbF2 with respect to those in the Pb atom are also performed and discussed. The accuracy of approximations used is estimated and the quality of the calculations is analyzed.

  12. Method of evaluating chemical shifts of X-ray emission lines in molecules and solids

    CERN Document Server

    Lomachuk, Yuriy V

    2013-01-01

    Method of evaluating chemical shifts of X-ray emission lines for sufficiently heavy atoms (beginning from period 4 elements) in chemical compounds is developed. This method is based on the pseudopotential model and one-center restoration method (to reconstruct the proper electronic structure in heavy-atom cores). The approximations of instantaneous transition and frozen inner core spinors of the atom are used for derivation of an expression for chemical shift as a difference between mean values of some effective operator. The method allows one to avoid evaluating small values (chemical shifts ~ 0.01{\\div}1 eV) as differences of very large values (transition energies ~ 1{\\div}100 keV in various compounds). The results of our calculations of chemical shifts for the K_{\\alpha1,2} and L transitions of the group 14 metal cations with respect to neutral atoms are presented. The calculations of chemical shift of K_{\\alpha1}-line in the Pb-core transition within PbO and PbF_2 with respect to the neutral Pb are also p...

  13. Suppression of Fiber Modal Noise Induced Radial Velocity Errors for Bright Emission-line Calibration Sources

    Science.gov (United States)

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  14. Investigating Possible Departures from Maxwellian Energy Distributions in Nebulae using High-Resolution Emission Line Spectra

    Science.gov (United States)

    Turbyfill, Amanda; Dinerstein, H. L.; Sterling, N. C.

    2014-01-01

    The derivation of ionic abundance ratios from collisionally excited emission lines in gaseous nebulae requires knowledge of the physical state of the gas, particularly the electron kinetic temperature, Te, to which the resulting abundances are highly sensitive. A long-standing problem in nebular analyses has been pervasive discrepancies among values of Te obtained from different diagnostic ratios for a single nebula. Recently, Nicholls et al. (2012, ApJ, 752, 148) have suggested that the nebular electrons may not obey an equilibrium Maxwell-Boltzmann (M-B) energy distribution, but instead follow a “κ distribution” seen in many solar system plasmas, a family of distributions for which the M-B distribution is the limiting case where κ → ∞. The high-energy tail of supra-thermal electrons in κ distributions have a disproportionate effect on strongly energy dependent quantities, such as Te diagnostics, for even modest departures from M-B distributions. We apply prescriptions given by Nicholls et al. (2013, ApJS, 207, 21) to high-resolution (R=36,700) optical spectra of 10 planetary nebulae obtained with the 2d-coudé echelle spectrograph on the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The advantages of these data include their broad spectral coverage and sufficiently high spectral resolution to separate blended lines and assess possible atmospheric absorption issues. The line fluxes were obtained using ROBOSPECT, an automated spectral line measurement package developed by Waters & Hollek (2013, PASP, 125, 1164). We solve both for Te under the assumption of M-B distributions, and the parameters of κ distributions consistent with the data. Our goal is to test whether the κ distribution hypothesis provides a better fit to the observed line ratios. Finally, we discuss effects on the derived ionic abundances under this alternate description of the particle energy distributions. This research was supported by NSF grant AST 0708245 and the John W

  15. Constraining UV continuum slopes of active galactic nuclei with cloudy models of broad-line region extreme-ultraviolet emission lines

    Energy Technology Data Exchange (ETDEWEB)

    Moloney, Joshua [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Michael Shull, J., E-mail: joshua.moloney@colorado.edu, E-mail: michael.shull@colorado.edu [Also at Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA, UK. (United Kingdom)

    2014-10-01

    Understanding the composition and structure of the broad-line region (BLR) of active galactic nuclei (AGNs) is important for answering many outstanding questions in supermassive black hole evolution, galaxy evolution, and ionization of the intergalactic medium. We used single-epoch UV spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope to measure EUV emission-line fluxes from four individual AGNs with 0.49 ≤ z ≤ 0.64, two AGNs with 0.32 ≤ z ≤ 0.40, and a composite of 159 AGNs. With the CLOUDY photoionization code, we calculated emission-line fluxes from BLR clouds with a range of density, hydrogen ionizing flux, and incident continuum spectral indices. The photoionization grids were fit to the observations using single-component and locally optimally emitting cloud (LOC) models. The LOC models provide good fits to the measured fluxes, while the single-component models do not. The UV spectral indices preferred by our LOC models are consistent with those measured from COS spectra. EUV emission lines such as N IV λ765, O II λ833, and O III λ834 originate primarily from gas with electron temperatures between 37,000 K and 55,000 K. This gas is found in BLR clouds with high hydrogen densities (n {sub H} ≥ 10{sup 12} cm{sup –3}) and hydrogen ionizing photon fluxes (Φ{sub H} ≥ 10{sup 22} cm{sup –2} s{sup –1}).

  16. The Chandra, HST, and VLA View of the Circumnuclear Extended Emission in the Narrow Emission Line Galaxy NGC 2110

    CERN Document Server

    Evans, D A; Kamenetska, M; Gallagher, S C; Kraft, R P; Hardcastle, M J; Weaver, K A; Evans, Daniel A.; Lee, Julia C.; Kamenetska, Maria; Gallagher, Sarah C.; Kraft, Ralph P.; Hardcastle, Martin J.; Weaver, Kimberly A.

    2006-01-01

    We present results from new Chandra and archival HST and VLA imaging observations of the circumnuclear extended emission in the nearby Type 2 Seyfert galaxy NGC 2110. We find resolved soft-band X-ray emission 4'' (~160 pc) north of the nucleus, which is spatially coincident with [OIII] emission, but lies just beyond the northern edge of the radio jet in the source. We find that shock-heating of multi-phase gas clouds can successfully account for this extended emission, although we cannot rule out alternative models, such as the scattering of nuclear radiation by ionized material, or pure photoionization from the nucleus. In addition, we detect kpc-scale (~30'') extended soft-band X-ray emission south of the nucleus. Finally, we compare our results for NGC 2110 with the prototypical Type 2 Seyfert galaxy NGC 1068, and suggest that different physical processes could produce extended circumnuclear X-ray emission in Seyfert galaxies.

  17. Development of a composite line source emission model for traffic interrupted microenvironments and its application in particle number emissions at a bus station

    Science.gov (United States)

    Wang, Lina; Jayaratne, Rohan; Heuff, Darlene; Morawska, Lidia

    A composite line source emission (CLSE) model was developed to specifically quantify exposure levels and describe the spatial variability of vehicle emissions in traffic interrupted microenvironments. This model took into account the complexity of vehicle movements in the queue, as well as different emission rates relevant to various driving conditions (cruise, decelerate, idle and accelerate), and it utilised multi-representative segments to capture the accurate emission distribution for real vehicle flow. Hence, this model was able to quickly quantify the time spent in each segment within the considered zone, as well as the composition and position of the requisite segments based on the vehicle fleet information, which not only helped to quantify the enhanced emissions at critical locations, but it also helped to define the emission source distribution of the disrupted steady flow for further dispersion modelling. The model then was applied to estimate particle number emissions at a bi-directional bus station used by diesel and compressed natural gas fuelled buses. It was found that the acceleration distance was of critical importance when estimating particle number emission, since the highest emissions occurred in sections where most of the buses were accelerating and no significant increases were observed at locations where they idled. It was also shown that emissions at the front end of the platform were 43 times greater than at the rear of the platform. Although the CLSE model is intended to be applied in traffic management and transport analysis systems for the evaluation of exposure, as well as the simulation of vehicle emissions in traffic interrupted microenvironments, the bus station model can also be used for the input of initial source definitions in future dispersion models.

  18. The Chandra, HST, and VLA View of the Circumnuclear Extended Emission in the Narrow Emission Line Galaxy NGC 2110

    OpenAIRE

    Evans, Daniel A.; Lee, Julia C.; Kamenetska, Maria; Gallagher, Sarah C.; Kraft, Ralph P.; Hardcastle, Martin J.; Weaver, Kimberly A.

    2006-01-01

    We present results from new Chandra and archival HST and VLA imaging observations of the circumnuclear extended emission in the nearby Type 2 Seyfert galaxy NGC 2110. We find resolved soft-band X-ray emission 4'' (~160 pc) north of the nucleus, which is spatially coincident with [OIII] emission, but lies just beyond the northern edge of the radio jet in the source. We find that shock-heating of multi-phase gas clouds can successfully account for this extended emission, although we cannot rule...

  19. C IV and He II line emission of Lyman α blobs: powered by shock-heated gas

    Science.gov (United States)

    Cabot, Samuel H. C.; Cen, Renyue; Zheng, Zheng

    2016-10-01

    Utilizing ab initio ultrahigh resolution hydrodynamical simulations, we investigate the properties of the interstellar and circumgalactic medium of Lyα blobs (LABs) at z = 3, focusing on three important emission lines: Lyα 1216 Å, He II 1640 Å and C IV 1549 Å. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed C IV/Lyα and He II/Lyα ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation and the C IV/Lyα and He II/Lyα ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the Lyα emission, the Lyα and C IV emission lines due to shock-heated gas are primarily collisional excitation driven and the He II emission line collisional ionization driven. We find that the density, temperature and metallicity of the gas responsible for each emission line is significantly distinct, in a multiphase interstellar and circumgalactic medium that is shock heated primarily by supernovae and secondarily by gravitational accretion of gas.

  20. Broad iron emission lines in Seyfert Galaxies - re-condensation of gas onto an inner disk below the ADAF

    OpenAIRE

    Meyer-Hofmeister, E.; Meyer, F

    2011-01-01

    Recent observations of Seyfert 1 AGN with Chandra, XMM-Newton and Suzaku revealed broad iron K_alpha emission lines, some relativistically blurred. For galactic black hole X-ray binaries XMM-Newton spectra during hard state also reveal the presence of a relativistic iron emission line and a thermal component, interpreted as an indication for a weak inner cool accretion disk underneath a hot corona. These thermal components were found after the transition from soft to hard spectral state and c...

  1. Near-IR dust and line emission from the central region of Mrk1066: Constraints from Gemini NIFS

    CERN Document Server

    Riffel, Rogemar A; Nagar, Neil M

    2010-01-01

    We present integral field spectroscopy of the inner 350 pc of the Mrk1066 obtained with Gemini NIFS at a spatial resolution of 35 pc. This high spatial resolution allowed us to observe, for the first time in this galaxy, an unresolved dust concentration with mass 0.014 M_Sun, which may be part of the dusty torus. The emission-line fluxes are elongated in PA=135/315deg in agreement with the [OIII] and radio images and, except for the H lines, are brighter to the north-west than to the south-east. The H emission is stronger to the south-east, where we find a large region of star-formation. The strong correlation between the radio emission and the highest emission-line fluxes indicates that the radio jet plays a fundamental role at these intensity levels. The H2 flux is more uniformly distributed and has an excitation temperature of 2100 K. Its origin appears to be circumnuclear gas heated by X-rays from the AGN. The [FeII] emission also is consistent with X-ray heating, but with additional emission due to excit...

  2. Space Telescope and Optical Reverberation Mapping Project. IV. Anomalous behavior of the broad ultraviolet emission lines in NGC 5548

    CERN Document Server

    Goad, M R; De Rosa, G; Kriss, G A; Edelson, R; Barth, A J; Ferland, G J; Kochanek, C S; Netzer, H; Peterson, B M; Bentz, M C; Bisogni, S; Crenshaw, D M; Denney, K D; Ely, J; Fausnaugh, M M; Grier, C J; Gupta, A; Horne, K D; Kaastra, J; Pancoast, A; Pei, L; Pogge, R W; Skielboe, A; Starkey, D; Vestergaard, M; Zu, Y; Anderson, M D; Arevalo, P; Bazhaw, C; Borman, G A; Boroson, T A; Bottorff, M C; Brandt, W N; Breeveld, A A; Brewer, B J; Cackett, E M; Carini, M T; Croxall, K V; Bonta, E Dalla; de Lorenzo-Caceres, A; Dietrich, M; Efimova, N V; Evans, P A; Filippenko, A V; Flatland, K; Gehrels, N; Geier, S; Gelbord, G M; Gonzalez, L; Gorjian, V; Grupe, D; Hall, P B; Hicks, S; Horenstein, D; Hutchison, T; Im, M; Jensen, J J; Joner, M D; Jones, J; Kaspi, S; Kelly, B C; Kennea, J A; Kim, M; Kim, S C; Klimanov, S A; Larionov, V M; Lee, J C; Leonard, D C; Lira, P; MacInnis, F; Manne-Nicholas, E R; Mathur, S; McHardy, I M; Montouri, C; Musso, R; Nazarov, S V; Norris, R P; Nousek, J A; Okhmat, D N; Papadakis, I; Parks, J R; Pott, J -U; Rafter, S E; Rix, H -W; Saylor, D A; Schimoia, J S; Schnulle, K; Sergeev, S G; Siegel, M; Spencer, M; Sung, H -I; Teems, K G; Treu, T; Turner, C S; Uttley, P; Villforth, C; Weiss, Y; Woo, J -H; Yan, H; Young, S; Zheng, W -K

    2016-01-01

    During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert~1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad emission-line variations decorrelated for ~60 to 70 days, starting ~75 days after the first HST/COS observation. Following this anomalous state, the flux and variability of the broad emission lines returned to a more normal state. This transient behavior, characterised by significant deficits in flux and equivalent width of the strong broad UV emission lines, is the first of its kind to be unambiguously identified in an active galactic nucleus reverberation mapping campaign. The largest corresponding emission-line flux deficits occurred for the high-ionization collisionally excited lines, C IV and Si IV(+O IV]), and also He II(+O III]), while the anomaly in Ly-alpha was substantially smaller. This pattern of behavior indicates a depletion in the flux of photons with E_{\\rm ph} >...

  3. Extended Carbon Line Emission in the Galaxy: Searching for Dark Molecular Gas along the G328 Sightline

    CERN Document Server

    Burton, Michael G; Braiding, Catherine; Freeman, Matthew; Kulesa, Craig; Wolfire, Mark G; Hollenbach, David J; Rowell, Gavin; Lau, James

    2015-01-01

    We present spectral data cubes of the [CI] 809GHz, 12CO 115GHz, 13CO 110GHz and HI 1.4GHz line emission from an 1 square degree region along the l = 328{\\deg} (G328) sightline in the Galactic Plane. Emission arises principally from gas in three spiral arm crossings along the sight line. The distribution of the emission in the CO and [CI] lines is found to be similar, with the [CI] slightly more extended, and both are enveloped in extensive HI. Spectral line ratios per voxel in the data cubes are found to be similar across the entire extent of the Galaxy. However, towards the edges of the molecular clouds the [CI]/13CO and 12CO/13CO line ratios rise by ~50%, and the [CI]/HI ratio falls by ~10$%. We attribute this to these sightlines passing predominantly through the surfaces of photodissociation regions (PDRs), where the carbon is found mainly as C or C+, while the H2 is mostly molecular, and the proportion of atomic gas also increases. We undertake modelling of the PDR emission from low density molecular clou...

  4. Observations of Ellerman bomb emission features in He I D3 and He I 10830 {\\AA}

    CERN Document Server

    Libbrecht, Tine; Rodríguez, Jaime de la Cruz; Leenaarts, Jorrit; Ramos, Andrés Asensio

    2016-01-01

    Context. Ellerman bombs (EBs) are short-lived emission features, characterized by extended wing emission in hydrogen Balmer lines. Until now, no distinct signature of EBs has been found in the He I 10830 {\\AA} line, and conclusive observations of EBs in He I D 3 have never been reported. Aims. We aim to study the signature of EBs in neutral helium triplet lines. Methods. The observations consist of 10 consecutive SST/TRIPPEL raster scans close to the limb, featuring the H$\\beta$, He I D3 and He I 10830 {\\AA} spectral regions. We also obtained raster scans with IRIS and make use of the SDO/AIA 1700 {\\AA} channel. We use Hazel to invert the neutral helium triplet lines. Results. Three EBs in our data show distinct emission signatures in neutral helium triplet lines, most prominently visible in the He I D3 line. The helium lines have two components: a broad and blue-shifted emission component associated with the EB, and a narrower absorption component formed in the overlying chromosphere. One of the EBs in our d...

  5. A line-of-sight electron cyclotron emission receiver for electron cyclotron resonance heating feedback control of tearing modes

    DEFF Research Database (Denmark)

    Oosterbeek, J.W.; Bürger, A.; Westerhof, E.;

    2008-01-01

    An electron cyclotron emission (ECE) receiver inside the electron cyclotron resonance heating (ECRH) transmission line has been brought into operation. The ECE is extracted by placing a quartz plate acting as a Fabry-Perot interferometer under an angle inside the electron cyclotron wave (ECW) bea...... for the control of plasma instabilities this line-of-sight ECE diagnostic removes the need to localize the instabilities in absolute coordinates. (C) 2008 American Institute of Physics....

  6. Nebular line emission from z > 7 galaxies in a cosmological simulation: rest-frame UV to optical lines

    Science.gov (United States)

    Shimizu, Ikkoh; Inoue, Akio K.; Okamoto, Takashi; Yoshida, Naoki

    2016-10-01

    We have performed very large and high-resolution cosmological hydrodynamic simulations in order to investigate detectability of nebular lines in the rest-frame ultraviolet (UV) to optical wavelength range from galaxies at z > 7. We find that the expected line fluxes are very well correlated with the apparent UV magnitudes. The C IV 1549 Å and C III] 1909 Å lines of galaxies brighter than 26 AB magnitudes are detectable with current facilities such as the Very Large Telescope (VLT) XShooter and the Keck Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE). Metal lines such as C IV 1549 Å, C III] 1909 Å, [O II] 3727 Å and [O III] 4959/5007 Å are good targets for spectroscopic observation with the Thirty-Metre Telescope (TMT), European Extremely Large Telescope (E-ELT), Giant Magellan Telescope (GMT) and James Webb Space Telescope (JWST). We also expect Hα and Hβ lines to be detectable with these telescopes. Additionally, we predict the detectability of nebular lines for z > 10 galaxies, which will be found with JWST, the Wide-Field Infrared Survey Telescope (WFIRST) and First Light And Reionization Explorer (FLARE) (11 ≤ z ≤ 15). We conclude that the C IV 1549 Å, C III] 1909 Å, [O III] 4959/5007 Å and Hβ lines from even z ˜15 galaxies could be strong targets for TMT, E-ELT and JWST. We also find that magnification by gravitational lensing is of great help in detecting such high-z galaxies. According to our model, the C III] 1909 Å line in z > 9 galaxy candidates is detectable even using current facilities.

  7. Measurements and Models for Complete and Accurate Line Emission Determinations in the Six EUV Channels of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The understanding of the line emission from heavy ions is still incomplete and often inaccurate, resulting in missing or incorrect line assignments and missing or...

  8. Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

    CERN Document Server

    Arnold, N D; Banks, G; Bechtold, R; Beczek, K; Benson, C; Berg, S; Berg, W; Biedron, S G; Biggs, J A; Boerste, K; Borland, M; Bosek, M; Brzowski, W R; Budz, J; Carwardine, J A; Castro, P; Chae, Y C; Christensen, S; Clark, C; Conde, M; Crosbie, E A; Decker, G A; Dejus, Roger J; Deleon, H; Den Hartog, P K; Deriy, B N; Dohan, D; Dombrowski, P; Donkers, D; Doose, C L; Dortwegt, R J; Edwards, G A; Eidelman, Y; Erdmann, M J; Error, J J; Ferry, R; Flood, R; Forrestal, J; Freund, H; Friedsam, H; Gagliano, J; Gai, W; Galayda, J N; Gerig, R; Gilmore, R L; Gluskin, E; Goeppner, G A; Goetzen, J; Gold, C; Grelick, A E; Hahne, M W; Hanuska, S; Harkay, K C; Harris, G; Hillman, A L; Hogrefe, R; Hoyt, J; Huang, Z; Jagger, J M; Jansma, W G; Jaski, M; Jones, S J; Keane, R T; Kelly, A L; Keyser, C; Kim, K J; Kim, S H; Kirshenbaum, M; Klick, J H; Knoerzer, K; Knott, M; Koldenhoven, R J; Labuda, S; Laird, R; Lang, J; Lenkszus, F R; Lessner, E S; Lewellen, J W; Li, Y; Lill, R M; Lumpkin, Alex H; Makarov, O A; Markovich, G M; McDowell, M; McDowell, W P; McNamara, P E; Meier, T; Meyer, D; Michalek, W; Milton, S V; Moe, H; Moog, E; Morrison, L; Nassiri, A; Noonan, J R; Otto, R; Pace, J; Pasky, S J; Penicka, J M; Pietryla, A F; Pile, G; Pitts, C; Power, J; Powers, T; Putnam, C C; Puttkammer, A J; Reigle, D; Reigle, L; Ronzhin, D; Rotela, E R; Russell, E F; Sajaev, Vadim; Sarkar, S; Scapino, J C; Schröder, K; Seglem, R A; Sereno, N S; Sharma, S K; Sidarous, J F; Singh, O; Smith, T L; Soliday, R; Sprau, G A; Stein, S J; Stejskal, B; Svirtun, V; Teng, L C; Theres, E; Thompson, K; Tieman, B J; Torres, J A; Trakhtenberg, E; Travish, G; Trento, G F; Vacca, J; Vasserman, I B; Vinokurov, N A; Walters, D R; Wang, J; Wang, X J; Warren, J; Wesling, S; Weyer, D L; Wiemerslage, G; Wilhelmi, K; Wright, R; Wyncott, D; Xu, S; Yang, B X; Yoder, W; Zabel, R B

    2001-01-01

    Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

  9. Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, N.D.; Attig, J.; Banks, G.; Bechtold, R.; Beczek, K.; Benson, C.; Berg, S.; Berg, W.; Biedron, S.G.; Biggs, J.A.; Borland, M.; Boerste, K.; Bosek, M.; Brzowski, W.R.; Budz, J.; Carwardine, J.A.; Castro, P.; Chae, Y.-C.; Christensen, S.; Clark, C.; Conde, M.; Crosbie, E.A.; Decker, G.A.; Dejus, R.J.; DeLeon, H.; Den Hartog, P.K.; Deriy, B.N.; Dohan, D.; Dombrowski, P.; Donkers, D.; Doose, C.L.; Dortwegt, R.J.; Edwards, G.A.; Eidelman, Y.; Erdmann, M.J.; Error, J.; Ferry, R.; Flood, R.; Forrestal, J.; Freund, H.; Friedsam, H.; Gagliano, J.; Gai, W.; Galayda, J.N.; Gerig, R.; Gilmore, R.L.; Gluskin, E.; Goeppner, G.A.; Goetzen, J.; Gold, C.; Gorski, A.J.; Grelick, A.E.; Hahne, M.W.; Hanuska, S.; Harkay, K.C.; Harris, G.; Hillman, A.L.; Hogrefe, R.; Hoyt, J.; Huang, Z.; Jagger, J.M.; Jansma, W.G.; Jaski, M.; Jones, S.J.; Keane, R.T.; Kelly, A.L.; Keyser, C.; Kim, K.-J.K.-J.; Kim, S.H.; Kirshenbaum, M.; Klick, J.H.; Knoerzer, K.; Koldenhoven, R.J.; Knott, M.; Labuda, S.; Laird, R.; Lang, J.; Lenkszus, F.; Lessner, E.S.; Lewellen, J.W.; Li, Y.; Lill, R.M.; Lumpkin, A.H.; Makarov, O.A.; Markovich, G.M.; McDowell, M.; McDowell, W.P.; McNamara, P.E.; Meier, T.; Meyer, D.; Michalek, W.; Milton, S.V. E-mail: milton@aps.anl.gov; Moe, H.; Moog, E.R.; Morrison, L.; Nassiri, A.; Noonan, J.R.; Otto, R.; Pace, J.; Pasky, S.J.; Penicka, J.M.; Pietryla, A.F.; Pile, G.; Pitts, C.; Power, J.; Powers, T.; Putnam, C.C.; Puttkammer, A.J.; Reigle, D.; Reigle, L.; Ronzhin, D.; Rotela, E.R.; Russell, E.F.; Sajaev, V.; Sarkar, S.; Scapino, J.C.; Schroeder, K.; Seglem, R.A.; Sereno, N.S.; Sharma, S.K.; Sidarous, J.F.; Singh, O.; Smith, T.L.; Soliday, R.; Sprau, G.A.; Stein, S.J.; Stejskal, B.; Svirtun, V.; Teng, L.C.; Theres, E.; Thompson, K.; Tieman, B.J.; Torres, J.A.; Trakhtenberg, E.M.; Travish, G.; Trento, G.F.; Vacca, J.; Vasserman, I.B.; Vinokurov, N.A.; Walters, D.R.; Wang, J.; Wang, X.J.; Warren, J.; Wesling, S.; Weyer, D.L.; Wiemerslage, G.; Wilhelmi, K.; Wright, R.

    2001-12-21

    Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

  10. New observations and models of circumstellar CO line emission of AGB stars in the Herschel SUCCESS programme

    CERN Document Server

    Danilovich, Taissa; Justtanont, K; Olofsson, H; Cerrigone, L; Bujarrabal, V; Alcolea, J; Cernicharo, J; Castro-Carrizo, A; Garcia-Lario, P; Marston, A

    2015-01-01

    CONTEXT: Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy elements and dust grains for the interstellar medium. The mass-loss rate can be well traced by carbon monoxide (CO) line emission. AIMS: We present new Herschel HIFI and IRAM 30m telescope CO line data for a sample of 53 galactic AGB stars. The lines cover a fairly large range of excitation energy from the $J=1\\to0$ line to the $J=9\\to8$ line, and even the $J=14\\to13$ line in a few cases. We perform radiative transfer modelling for 38 of these sources to estimate their mass-loss rates. METHODS: We used a radiative transfer code based on the Monte Carlo method to model the CO line emission. We assume spherically symmetric circumstellar envelopes that are formed by a constant mass-loss rate through a smoothly accelerating wind. RESULTS: We find models that are consistent across...

  11. Relative timing of solar prompt. gamma. -ray line and X-ray emission produced by flare accelerated ions and electrons

    Energy Technology Data Exchange (ETDEWEB)

    Hulot, E.; Vilmer, N.; Trottet, G.

    1988-09-25

    SMM and Hinotori observations show that the peak time of the ..gamma..-ray emission is sometimes delayed with respect to the one of the hard X-ray flux. Such delays may be interpreted either as an evidence of a two step acceleration process of electrons and ions or as the result of the partial trapping and/or propagation of the particles from the acceleration region to the interaction site. Here we focus on the latter hypothesis and present some preliminary calculations of the time dependent transport of energetic ions. Preliminary estimates of the 4.4 MeV line emission are used to discuss the relative timing of Hard X-ray and ..gamma..-ray emissions. One difficulty with the preliminary model discussed here is that the number of ions involved in the ..gamma..-ray line production is very large. Nevertheless, for reasonable parameters, a good agreement is found between observed and expected delays.

  12. Characterisation of neutral hydrogen beam by means of active balmer-a-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, C

    1999-01-01

    Neutral particle beams are used in thermal nuclear experiments for plasma heating and current drive, and as a diagnostic tool for active spectroscopy. Within the frame of this thesis eight viewing lines for H{sub {alpha}}-spectroscopy have been installed at the end of the injector to observe the fully established neutral beam. The viewing lines are all parallel to the horizontal plane and include small angles with the beam axis, in order to make use of the Doppler effect which separates the signals from the three energy components from each other and from the H{sub {alpha}}-emission of the thermal particles. A multi-Gaussian fit code has been applied to give the amplitudes, positions and widths of the Gauss shaped signals. From this data, the beam composition and, including the physics processes in the acceleration and neutralisation sections, the ion species fractions in the source have been calculated. Furthermore, the vertical density profile and an estimation of the absolute particle density distribution based on an absolute calibration resulted. From the line positions the exact acceleration voltage has been obtained. The line widths allow an estimate of the horizontal divergence. During this work, two ion sources, the 'Pagoda' and the 'Sourcette', have been investigated to obtain the ion species ratio and beam profile. The comparison of the spectroscopic with the calorimetric results gives a useful insight into the beam steering geometry. (author)

  13. COEXISTENCE OF GRAVITATIONALLY-BOUND AND RADIATION-DRIVEN C IV EMISSION LINE REGIONS IN ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    There are mutually contradictory views in the literature of the kinematics and structure of high-ionization line (e.g., C IV) emitting regions in active galactic nuclei (AGNs). Two kinds of broad emission line region (BELR) models have been proposed, outflow and gravitationally-bound BELR, which are supported, respectively, by blueshift of the C IV line and reverberation mapping observations. To reconcile these two apparently different models, we present a detailed comparison study between the C IV and Mg II lines using a sample of AGNs selected from the Sloan Digital Sky Survey. We find that the kinematics of the C IV region is different from that of Mg II, which is thought to be controlled by gravity. A strong correlation is found between the blueshift and asymmetry of the C IV profile and the Eddington ratio. This provides strong observational support for the postulation that the outflow is driven by radiation pressure. In particular, we find robust evidence that the C IV line region is largely dominated by outflow at high Eddington ratios, while it is primarily gravitationally-bounded at low Eddington ratios. Our results indicate that these two emitting regions coexist in most AGNs. The emission strength from these two gases varies smoothly with Eddington ratio in opposite ways. This explanation naturally reconciles the apparently contradictory views proposed in previous studies. Finally, candidate models are discussed which can account for both the enhancement of outflow emission and suppression of normal BEL in AGNs with high Eddington ratios.

  14. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

    Science.gov (United States)

    Mendigutía, I.; Oudmaijer, R. D.; Rigliaco, E.; Fairlamb, J. R.; Calvet, N.; Muzerolle, J.; Cunningham, N.; Lumsden, S. L.

    2015-09-01

    Correlations between the accretion luminosity and emission line luminosities (Lacc and Lline) of pre-main-sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) Lacc-Lline correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L*) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the Lacc-Lline correlations depend on the Lacc-L* relationship. We conclude that because PMS stars show the Lacc-L* correlation immediately implies that Lacc also correlates with the luminosity of all emission lines, for which the Lacc-Lline correlations alone do not prove any physical connection with accretion but can only be used with practical purposes to roughly estimate accretion rates. When looking for correlations with possible physical meaning, we suggest that Lacc/L* and Lline/L* should be used instead of Lacc and Lline. Finally, the finding that Lacc has a steeper dependence on L* for T Tauri stars than for intermediate-mass Herbig Ae/Be stars is also discussed. That is explained from the magnetospheric accretion scenario and the different photospheric properties in the near-UV.

  15. On line photochemically induced excitation-emission-kinetic four-way data

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez Giron, A.; Duran-Meras, I.; Espinosa-Mansilla, A. [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain); Munoz de la Pena, A. [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain)], E-mail: arsenio@unex.es; Canada Canada, F. [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain); Olivieri, A.C. [Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Instituto de Quimica de Rosario (CONICET), Suipacha 531, S2002LRK Rosario (Argentina)

    2008-08-01

    The determination of folic acid and its two main serum metabolites, 5-methyltetrahydrofolic acid and tetrahydrofolic acid, has been accomplished using four-way data modelled by the third-order multivariate calibration methods unfolded and N-dimensional partial least-squares (U-PLS and N-PLS), in combination with the separate procedure known as residual trilinearization (RTL). The four-way data were acquired by following the photochemical reaction of these compounds by on line irradiation with a UV lamp. The excitation-emission matrices (EEMs) were recorded as a function of the irradiation time, using a fast scanning spectrofluorimeter. The method achieves selectivity from the different rates at which the corresponding photoproducts of the folic acid derivatives are formed and degraded. Several N-dimensional chemometric algorithms were used and the method was applied to the determination of these compounds in serum samples. The best algorithms to perform the multivariate calibration were U-PLS and N-PLS in combination with the separate residual trilinearization procedure, achieving the second-order advantage. The approach allows minimizing or eliminating traditionally time-consuming sample pre-treatments and can facilitate quantifying an analyte in its native environment.

  16. Formation of emission line dots and extremely metal-deficient dwarfs from almost dark galaxies

    CERN Document Server

    Bekki, Kenji

    2015-01-01

    Recent observations have discovered a number of extremely gas-rich very faint dwarf galaxies possibly embedded in low-mass dark matter halos. We investigate star formation histories of these gas-rich dwarf ("almost dark") galaxies both for isolated and interacting/merging cases. We find that although star formation rates (SFRs) are very low (<10^-5 M_sun/yr) in the simulated dwarfs in isolation for the total halo masses (M_h) of 10^8-10^9 M_sun, they can be dramatically increased to be ~ 10^{-4} M_sun/yr when they interact or merge with other dwarfs. These interacting faint dwarfs with central compact HII regions can be identified as isolated emission line dots ("ELdots") owing to their very low surface brightness envelopes of old stars. The remnant of these interacting and merging dwarfs can finally develop central compact stellar systems with very low metallicities (Z/Z_sun<0.1), which can be identified as extremely metal-deficient ("XMD") dwarfs. These results imply that although there would exist ma...

  17. Intranight Optical Variability of Radio-Quiet Weak Emission Line Quasars-IV

    CERN Document Server

    Kumar, Parveen; Gopal-Krishna,

    2016-01-01

    We report an extension of our program to search for radio-quiet BL Lac candidates using intra-night optical variability (INOV) as a probe. The present INOV observations cover a well-defined representative set of 10 `radio-quiet weak-emission-line quasars' (RQWLQs), selected from a newly published sample of 46 such sources, derived from the Sloan Digital Sky Survey (Data release 7). Intra-night CCD monitoring of the 10 RQWLQs was carried out in 18 sessions lasting at least 3.5 hours. For each session, differential light curves (DLCs) of the target RQWLQ were derived relative to two steady comparison stars monitored simultaneously. Combining these new data with those already published by us for 15 RQWLQs monitored in 30 sessions, we estimate an INOV duty cycle of $\\sim 3\\%$ for the RQWLQs, which appears inconsistent with BL Lacs. However, the observed INOV events (which occurred in just two of the sessions) are strong (with a fractional variability amplitude $\\psi >$ 10\\%), hence blazar-like. We briefly point o...

  18. Intranight optical variability of radio-quiet weak emission line quasars - IV

    Science.gov (United States)

    Kumar, Parveen; Chand, Hum; Gopal-Krishna

    2016-09-01

    We report an extension of our programme to search for radio-quiet BL Lac candidates using intranight optical variability (INOV) as a probe. The present INOV observations cover a well-defined representative set of 10 `radio-quiet weak-emission-line quasars' (RQWLQs), selected from a newly published sample of 46 such sources, derived from the Sloan Digital Sky Survey (Data release 7). Intranight CCD monitoring of the 10 RQWLQs was carried out in 18 sessions lasting at least 3.5 h. For each session, differential light curves of the target RQWLQ were derived relative to two steady comparison stars monitored simultaneously. Combining these new data with those already published by us for 15 RQWLQs monitored in 30 sessions, we estimate an INOV duty cycle of ˜3 per cent for the RQWLQs, which appears inconsistent with BL Lacs. However, the observed INOV events (which occurred in just two of the sessions) are strong (with a fractional variability amplitude ψ > 10 per cent), hence blazar-like. We briefly point out the prospects of an appreciable rise in the estimated INOV duty cycle for RQWLQs with a relatively modest increase in sensitivity for monitoring these rather faint objects.

  19. Tracing Slow Winds from T Tauri Stars via Low Velocity Forbidden Line Emission

    CERN Document Server

    Simon, M N; Edwards, S; Feng, W; Gorti, U; Hollenbach, D; Rigliaco, E; Keane, J T

    2016-01-01

    Using Keck/HIRES spectra {\\Delta}v ~ 7 km/s, we analyze forbidden lines of [O I] 6300 {\\AA}, [O I] 5577 {\\AA} and [S II] 6731 {\\AA} from 33 T Tauri stars covering a range of disk evolutionary stages. After removing a high velocity component (HVC) associated with microjets, we study the properties of the low velocity component (LVC). The LVC can be attributed to slow disk winds that could be magnetically (MHD) or thermally (photoevaporative) driven. Both of these winds play an important role in the evolution and dispersal of protoplanetary material. LVC emission is seen in all 30 stars with detected [O I] but only in 2 out of eight with detected [S II] , so our analysis is largely based on the properties of the [O I] LVC. The LVC itself is resolved into broad (BC) and narrow (NC) kinematic components. Both components are found over a wide range of accretion rates and their luminosity is correlated with the accretion luminosity, but the NC is proportionately stronger than the BC in transition disks. The FWHM of...

  20. Uncovering the Spectral Energy Distribution in Active Galaxies Using High Ionization Mid-infrared Emission Lines

    CERN Document Server

    Meléndez, M; Weaver, K A; Mushotzky, R F

    2011-01-01

    The shape of the spectral energy distribution of active galaxies in the EUV--soft X-ray band (13.6 eV to 1 keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the spectral energy distribution in this energy band, we have generated a set of photoionization models which reproduce the small dispersion found in correlations between high-ionization mid-infrared emission lines in a sample of hard X-ray selected AGN. Our calculations show that a broken power-law continuum model is sufficient to reproduce the [Ne V]14.32 mm/[NeIII], [Ne V]24.32mm/[O IV]25.89mm and [O IV] 25.89mm/[Ne III] ratios, and does not require the addition of a "big bump" EUV model component. We constrain the EUV--soft X-ray slope, alpha_i, to be between 1.5 -- 2.0 and derive a best fit of alpha_i ~ 1.9 for Seyfert 1 galaxies, consistent with previous studies of intermediate redshift quasars. If we assume a blue bump model, most sources in our sample have derived temperatures b...