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Sample records for hole candidate swift

  1. NuSTAR and SWIFT Observations of the Black Hole Candidate XTE J1908+094 during its 2013 Outburst

    DEFF Research Database (Denmark)

    Tao, Lian; Tomsick, John A.; Walton, Dominic J.

    2015-01-01

    The black hole (BH) candidate XTE J1908+094 went into outburst for the first time since 2003 in 2013 October. We report on an observation with the Nuclear Spectroscopic Telescope Array (NuSTAR) and monitoring observations with Swift during the outburst. NuSTAR caught the source in the soft state...

  2. Discovery and Evolution of the New Black Hole Candidate Swift J1539.2-6227 During Its 2008 Outburst

    Science.gov (United States)

    Krimm, H. A.; Tomsick, J. A.; Markwardt, C. B.; Brocksopp, C.; Grise, F.; Kaaret, P.; Romano, P.

    2010-01-01

    We report on the discovery by the Swift Gamma-Ray Burst Explorer of the black hole candidate Swift J1539.2-6227 and the subsequent course of an outburst beginning in November 2008 and lasting at least seven months. The source was discovered during normal observations with the Swift Burst Alert Telescope (BAT) on 2008 November 25. An extended observing campaign with the Rossi X-Ray Timing Explorer (RXTE) and Swift provided near-daily coverage over 176 days, giving us a rare opportunity to track the evolution of spectral and timing parameters with fine temporal resolution through a series of spectral states. The source was first detected in a hard state during which strong low-frequency quasiperiodic oscillations (QPOs) were detected. The QPOs persisted for about 35 days and a signature of the transition from the hard to soft intermediate states was seen in the timing data. The source entered a short-lived thermal state about 40 days after the start of the outburst. There were variations in spectral hardness as the source flux declined and returned to a hard state at the end of the outburst. The progression of spectral states and the nature of the timing features provide strong evidence that Swift J1539.2-6227 is a candidate black hole in a low-mass X-ray binary system.

  3. The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift

    DEFF Research Database (Denmark)

    Del Santo, M.; Kuulkers, E.; Bozzo, E.

    2011-01-01

    The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...

  4. The evolving polarized jet of black hole candidate Swift J1745-26

    NARCIS (Netherlands)

    Curran, P.A.; Coriat, M.; Miller-Jones, J.C.A.; Armstrong, R.P.; Edwards, P.G.; Sivakoff, G.R.; Woudt, P.; Altamirano, D.; Belloni, T.M.; Corbel, S.; Fender, R.P.; Körding, E.G.; Krimm, H.A.; Markoff, S.; Migliari, S.; Russell, D.M.; Stevens, J.; Tzioumis, T.

    2014-01-01

    Swift J1745−26 is an X-ray binary towards the Galactic Centre that was detected when it went into outburst in 2012 September. This source is thought to be one of a growing number of sources that display ‘failed outbursts’, in which the self-absorbed radio jets of the transient source are never fully

  5. Combined Spectral and Timing Analysis of the Black Hole Candidate MAXI J1659-152 Discovered by MAXI and Swift

    Science.gov (United States)

    Yamaoka, Kazutaka; Allured, Ryan; Kaaret, Philip; Kennea, Jamie A.; Kawaguchi, Toshihiro; Gandhi, Poshak; Shaposhnikov, Nicholai; Ueda, Yoshihiro; Nakahira, Satoshi; Kotani, Taro; hide

    2011-01-01

    We report on X-ray spectral and timing results of the new black hole candidate (BHC) MAXI J1659-152 with the orbital period of 2.41 hours (shortest among BHCs) in the 2010 outburst from 65 Rossi X-ray Timing Explorer (RXTE) observations and 8 simultaneous Swift and RXTE observations. According to the definitions of the spectral states in Remillard & McClintock (2006), most of the observations have been classified into the intermediate state. All the X-ray broadband spectra can be modeled by a multi-color disk plus a power-law with an exponential cutoff or a multi-color disk plus a Comptonization component. During the initial phase of the outburst, a high energy cutoff was visible at 30-40 keV. The innermost radius of the disk gradually decreased by a factor of more than 3 from the onset of the outburst and reached a constant value of 35 d(sub 10)cos(i sup -1/2) km, where d(sub 10) is the distance in units of 10 kpc and i is the inclination. The type-C quasi-periodic oscillation (QPO) frequency varied from 1.6 Hz to 7.3 Hz in association with a change of the innermost radius, while the innermost radius remained constant during the type-B QPO detections at 1.6-4.1 Hz. Hence, we suggest that the origin of the type-B QPOs is different from that of type-C QPOs, the latter of which would originate from the disk truncation radius. Assuming the constant innermost radius in the latter phase of the outburst as the innermost stable circular orbit, the black hole mass in MAXI J1659-152 is estimated to be 3.6-8.0 solar mass for a distance of 5.3-8.6 kpc and an inclination angle of 60-75 degrees.

  6. The Evolving Polarized Jet of Black Hole Candidate Swift J1745-26

    Science.gov (United States)

    Curran, P. A.; Coriat, M.; Miller-Jones, J. C. A.; Armstrong, R. P.; Edwards, P. G.; Sivakoff, G. R.; Woudt, P.; Altamirano, D.; Belloni, T. M.; Corbel, S.; hide

    2013-01-01

    Swift J1745-26 is an X-ray binary towards the Galactic Centre that was detected when it went into outburst in September 2012. This source is thought to be one of a growing number of sources that display "failed outbursts", in which the self-absorbed radio jets of the transient source are never fully quenched and the thermal emission from the geometrically-thin inner accretion disk never fully dominates the X-ray flux. We present multifrequency data from the Very Large Array, Australia Telescope Compact Array and Karoo Array Telescope (KAT- 7) radio arrays, spanning the entire period of the outburst. Our rich data set exposes radio emission that displays a high level of large scale variability compared to the X-ray emission and deviations from the standard radio-X-ray correlation that are indicative of an unstable jet and confirm the outburst's transition from the canonical hard state to an intermediate state. We also observe steepening of the spectral index and an increase of the linear polarization to a large fraction (is approx. equal to 50%) of the total flux, as well as a rotation of the electric vector position angle. These are consistent with a transformation from a self-absorbed compact jet to optically-thin ejecta - the first time such a discrete ejection has been observed in a failed outburst - and may imply a complex magnetic field geometry.

  7. The black hole candidate IGR J17091-3624 going to quiescence

    NARCIS (Netherlands)

    Altamirano, D.; Wijnands, R.; Belloni, T.

    2013-01-01

    We report preliminary results on our Swift/XRT monitoring observations of the current outburst of the black hole candidate IGR J17091-3624 (e.g. Altamirano et al. 2011, ApJL, 742, 17, and references therein). Since our last report on 31 Jan 2013 (ATEL #4773), the X-ray flux as measured from

  8. Testing black hole candidates with electromagnetic radiation

    Science.gov (United States)

    Bambi, Cosimo

    2017-04-01

    Astrophysical black hole candidates are thought to be the Kerr black holes of general relativity, but there is not yet direct observational evidence that the spacetime geometry around these objects is described by the Kerr solution. The study of the properties of the electromagnetic radiation emitted by gas or stars orbiting these objects can potentially test the Kerr black hole hypothesis. This paper reviews the state of the art of this research field, describing the possible approaches to test the Kerr metric with current and future observational facilities and discussing current constraints.

  9. Swift J1112.2-8238: a candidate relativistic tidal disruption flare

    Science.gov (United States)

    Brown, G. C.; Levan, A. J.; Stanway, E. R.; Tanvir, N. R.; Cenko, S. B.; Berger, E.; Chornock, R.; Cucchiaria, A.

    2015-10-01

    We present observations of Swift J1112.2-8238, and identify it as a candidate relativistic tidal disruption flare. The outburst was first detected by Swift/Burst Alert Telescope (BAT) in 2011 June as an unknown, long-lived (order of days) gamma-ray transient source. We show that its position is consistent with the nucleus of a faint galaxy for which we establish a likely redshift of z = 0.89 based on a single emission line that we interpret as the blended [O II] λ3727 doublet. At this redshift, the peak X-ray/gamma-ray luminosity exceeded 1047 erg s-1, while a spatially coincident optical transient source had i' ˜ 22 (Mg ˜ -21.4 at z = 0.89) during early observations, ˜20 d after the Swift trigger. These properties place Swift J1112.2-8238 in a very similar region of parameter space to the two previously identified members of this class, Swift J1644+57 and Swift J2058+0516. As with those events the high-energy emission shows evidence for variability over the first few days, while late-time observations, almost 3 yr post-outburst, demonstrate that it has now switched off. Swift J1112.2-8238 brings the total number of such events observed by Swift to three, interestingly all detected by Swift over a ˜3 month period (<3 per cent of its total lifetime as of 2015 March). While this suggests the possibility that further examples may be uncovered by detailed searches of the BAT archives, the lack of any prime candidates in the years since 2011 means these events are undoubtedly rare.

  10. Swift J164449.3+573451 and Swift J2058.4+0516: Black hole mass estimates for tidal disruption event sources

    Science.gov (United States)

    Seifina, Elena; Titarchuk, Lev; Virgilli, Enrico

    2017-11-01

    A tidal disruption event (TDE) is an astronomical phenomenon in which a previously dormant black hole (BH) destroys a star passing too close to its central part. We analyzed the flaring episode detected from the TDE sources, Swift J164449.3+573451 and Swift J2058.4+0516 (hereafter Swift J1644+57 and Swift J2058+05, respectively) using RXTE, Swift and Suzaku data. The spectra are well fitted by the so called Bulk Motion Comptonization model for which the best-fit photon index Γ varies from 1.1 to 1.8. We have firmly established the saturation of the photon index versus mass accretion rate at Γsat about 1.7-1.8. The saturation of Γ is usually identified as a signature of a BH now established in Swift J1644+57 and Swift J2058+05. In Swift J1644+57 we found the relatively low Γsat values which indicate a high electron (plasma) temperature, kTe 30-40 keV. This is also consistent with high cutoff energies, Ecut 60-80 keV found using best fits of the RXTE spectra. Swift J2058+05 shows a lower electron temperature, kTe 4-10 keV than that for Swift J1644+57. For the BH mass estimate we used the scaling technique taking the Galactic BHs, GRO J1655-40,GX 339-4, Cyg X-1 and 4U 1543-47as reference sources and found that the BH mass in Swift J1644+57 is MBH ≥ 7 × 106M⊙ assuming the distance to this source of 1.5 Gpc. For Swift J2058+05 we obtain MBH ≥ 2 × 107M⊙ assuming the distance to this source of 3.7 Gpc. We have also found that the seed (disk) photon temperatures are quite low, of order of 100-400 eV, in both of the sources, which are consistent with the estimated BH masses.

  11. Swift Follow-Up Observations of Candidate Gravitational-Wave Transient Events

    Science.gov (United States)

    Evans, P. A.; Fridriksson, J. K.; Gehrels, N.; Homan, J.; Osborne, J. P.; Siegel, M.; Beardmore, A.; Handbauer, P.; Gelbord, J.; Kennea, J. A.; hide

    2012-01-01

    We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observatory (within 12 hr). Image transient detection was used to analyze the collected electromagnetic data, which were found to be consistent with background. Off-line analysis of the GW data alone has also established that the selected GW events show no evidence of an astrophysical origin; one of them is consistent with background and the other one was a test, part of a "blind injection challenge." With this work we demonstrate the feasibility of rapid follow-ups of GW transients and establish the sensitivity improvement joint electromagnetic and GW observations could bring. This is a first step toward an electromagnetic follow-up program in the regime of routine detections with the advanced GW instruments expected within this decade. In that regime, multi-wavelength observations will play a significant role in completing the astrophysical identification of GW sources. We present the methods and results from this first combined analysis and discuss its implications in terms of sensitivity for the present and future instruments.

  12. Optical Precursors to Black Hole X-Ray Binary Outbursts: An Evolving Synchrotron Jet Spectrum in Swift J1357.2–0933

    Science.gov (United States)

    Russell, David M.; Qasim, Ahlam Al; Bernardini, Federico; Plotkin, Richard M.; Lewis, Fraser; Koljonen, Karri I. I.; Yang, Yi-Jung

    2018-01-01

    We present six years of optical monitoring of the black hole (BH) candidate X-ray binary Swift J1357.2–0933, during and since its discovery outburst in 2011. On these long timescales, the quiescent light curve is dominated by high amplitude, short-term (seconds–days) variability spanning ∼2 mag, with an increasing trend of the mean flux from 2012 to 2017 that is steeper than in any other X-ray binary found to date (0.17 mag yr‑1). We detected the initial optical rise of the 2017 outburst of Swift J1357.2–0933, and we report that the outburst began between 2017 April 1 and 6. Such a steep optical flux rise preceding an outburst is expected according to disk instability models, but the high amplitude variability in quiescence is not. Previous studies have shown that the quiescent spectral, polarimetric, and rapid variability properties of Swift J1357.2–0933 are consistent with synchrotron emission from a weak compact jet. We find that a variable optical/infrared spectrum is responsible for the brightening: a steep, red spectrum before and soon after the 2011 outburst evolves to a brighter, flatter spectrum since 2013. The evolving spectrum appears to be due to the jet spectral break shifting from the infrared in 2012 to the optical in 2013, then back to the infrared by 2016–2017 while the optical remains relatively bright. Swift J1357.2–0933 is a valuable source to study BH jet physics at very low accretion rates and is possibly the only quiescent source in which the optical jet properties can be regularly monitored.

  13. Effects of model approximations for electron, hole, and photon transport in swift heavy ion tracks

    Science.gov (United States)

    Rymzhanov, R. A.; Medvedev, N. A.; Volkov, A. E.

    2016-12-01

    The event-by-event Monte Carlo code, TREKIS, was recently developed to describe excitation of the electron subsystems of solids in the nanometric vicinity of a trajectory of a nonrelativistic swift heavy ion (SHI) decelerated in the electronic stopping regime. The complex dielectric function (CDF) formalism was applied in the used cross sections to account for collective response of a matter to excitation. Using this model we investigate effects of the basic assumptions on the modeled kinetics of the electronic subsystem which ultimately determine parameters of an excited material in an SHI track. In particular, (a) effects of different momentum dependencies of the CDF on scattering of projectiles on the electron subsystem are investigated. The 'effective one-band' approximation for target electrons produces good coincidence of the calculated electron mean free paths with those obtained in experiments in metals. (b) Effects of collective response of a lattice appeared to dominate in randomization of electron motion. We study how sensitive these effects are to the target temperature. We also compare results of applications of different model forms of (quasi-) elastic cross sections in simulations of the ion track kinetics, e.g. those calculated taking into account optical phonons in the CDF form vs. Mott's atomic cross sections. (c) It is demonstrated that the kinetics of valence holes significantly affects redistribution of the excess electronic energy in the vicinity of an SHI trajectory as well as its conversion into lattice excitation in dielectrics and semiconductors. (d) It is also shown that induced transport of photons originated from radiative decay of core holes brings the excess energy faster and farther away from the track core, however, the amount of this energy is relatively small.

  14. SWIFT X-RAY TELESCOPE TIMING OBSERVATIONS OF THE BLACK HOLE BINARY SWIFT J1753.5-0127: DISK-DILUTED FLUCTUATIONS IN THE OUTBURST PEAK

    Energy Technology Data Exchange (ETDEWEB)

    Kalamkar, M.; Van der Klis, M.; Uttley, P.; Altamirano, Diego; Wijnands, Rudy, E-mail: m.n.kalamkar@uva.nl [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098-XH Amsterdam (Netherlands)

    2013-04-01

    After a careful analysis of the instrumental effects on the Poisson noise to demonstrate the feasibility of detailed stochastic variability studies with the Swift X-Ray Telescope (XRT), we analyze the variability of the black hole X-ray binary SWIFT J1753.5-0127 in all XRT observations during 2005-2010. We present the evolution of the power spectral components along the outburst in two energy bands: soft (0.5-2 keV) and hard (2-10 keV), and in the hard band we find results consistent with those from the Rossi X-Ray Timing Explorer (RXTE). The advantage of the XRT is that we can also explore the soft band not covered by RXTE. The source has previously been suggested to host an accretion disk extending down to close to the black hole in the low hard state, and to show low-frequency variability in the soft-band intrinsic to this disk. Our results are consistent with this, with stronger low-frequency variability at low intensities in the soft than in the hard band. From our analysis, we are able to present the first measurements of the soft-band variability in the peak of the outburst. We find the soft band to be less variable than the hard band, especially at high frequencies, opposite to what is seen at low intensity. Both results can be explained within the framework of a simple two emission-region model where the hot flow is more variable in the peak of the outburst and the disk is more variable at low intensities.

  15. Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1

    Science.gov (United States)

    Webb, N. A.; Guérou, A.; Ciambur, B.; Detoeuf, A.; Coriat, M.; Godet, O.; Barret, D.; Combes, F.; Contini, T.; Graham, Alister W.; Maccarone, T. J.; Mrkalj, M.; Servillat, M.; Schroetter, I.; Wiersema, K.

    2017-06-01

    Aims: ESO 243-49 HLX-1, otherwise known as HLX-1, is an intermediate mass black hole (IMBH) candidate located 8'' (3.7 Kpc) from the centre of the edge-on S0 galaxy ESO 243-49. How the black hole came to be associated with this galaxy, and the nature of the environment in which it resides, remain unclear. Using multi-wavelength observations we aim to investigate the nature of the medium surrounding HLX-1, search for evidence of past mergers with ESO 243-49 and constrain parameters of the galaxy, including the mass of the expected central supermassive black hole, essential for future modelling of the interaction of the IMBH and ESO 243-49. Methods: We have reduced and analysed integral field unit observations of ESO 243-49 that were taken with the MUSE instrument on the VLT. Using complementary multi-wavelength data, including X-shooter, HST, Swift, Chandra and ATCA data, we have further examined the vicinity of HLX-1. We additionally examined the nature of the host galaxy and estimate the mass of the central supermassive black hole in ESO 243-49 using (black hole mass)-(host spheroid) scaling relations and the fundamental plane of black hole activity. Results: No evidence for a recent minor-merger that could result in the presence of the IMBH is discerned, but the data are compatible with a scenario in which minor mergers may have occurred in the history of ESO 243-49. The MUSE data reveal a rapidly rotating disc in the centre of the galaxy, around the supermassive black hole. The mass of the supermassive black hole at the centre of ESO 243-49 is estimated to be 0.5-23 × 107M⊙. Studying the spectra of HLX-1, that were taken in the low and hard state, we determine Hα flux variability to be at least a factor 6, compared to observations taken during the high and soft state. This Hα flux variability over one year indicates that the line originates close to the intermediate mass black hole, excluding the possibility that the line emanates from a surrounding nebula

  16. Recoiling Black Holes: Electromagnetic Signatures, Candidates, and Astrophysical Implications

    Directory of Open Access Journals (Sweden)

    S. Komossa

    2012-01-01

    Full Text Available Supermassive black holes (SMBHs may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically offset from their host galaxies. The presence of the “kicks” has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of active galactic nuclei (AGN. Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which have emerged, including follow-up studies of the candidate recoiling SMBH of SDSSJ092712.65+294344.0.

  17. NuSTARand Swift observations of the very high state in GX 339-4: Weighing the black hole with X-rays

    DEFF Research Database (Denmark)

    Parker, M. L.; Tomsick, J. A.; Kennea, J. A.

    2016-01-01

    We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0.95(-0.08)(+0.02) and ......We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0...

  18. An X-ray view of the very faint black hole X-ray transient Swift J1357.2-0933 during its 2011 outburst

    NARCIS (Netherlands)

    Armas Padilla, M.; Wijnands, R.; Altamirano, D.; Méndez, M.; Miller, J. M.; Degenaar, N.

    We report on the X-ray spectral (using XMM-Newton data) and timing behaviour [using XMM-Newton and Rossi X-ray Timing Explorer (RXTE) data] of the very faint X-ray transient and black hole system Swift J1357.2-0933 during its 2011 outburst. The XMM-Newton X-ray spectrum of this source can be

  19. An X-ray view of the very faint black hole X-ray transient Swift J1357.2-0933 during its 2011 outburst

    NARCIS (Netherlands)

    Armas Padilla, M.; Wijnands, R.; Altamirano, D.; Méndez, M.; Miller, J.M.; Degenaar, N.

    2014-01-01

    We report on the X-ray spectral (using XMM-Newton data) and timing behaviour [using XMM-Newton and Rossi X-ray Timing Explorer (RXTE) data] of the very faint X-ray transient and black hole system Swift J1357.2-0933 during its 2011 outburst. The XMM-Newton X-ray spectrum of this source can be

  20. Evidence for quiescent synchrotron emission in the black hole X-ray transient Swift J1357.2–0933

    Directory of Open Access Journals (Sweden)

    Shahbaz T.

    2013-12-01

    Full Text Available We present high time-resolution optical and infrared observations of the edge-on black hole X-ray transient Swift J1357.2-0933. Our data taken in 2012 shows the system to be at its pre-outburst magnitude and so the system is in quiescence. In contrast to other X-ray transients, the quiescent light curves of Swift J1357.2-0933 do not show the secondary star’s ellipsoidal modulation. The optical and infrared light curves is dominated by variability with an optical fractional rms of about 20 per cent, much larger than what is observed in other systems. The quiescent ultraviolet to mid-IR spectral energy distribution in quiescence is dominated by a nonthermal component with a power–law index of −1.4, (the broad-band rms SED has a similar index which arises from optically thin synchrotron emission from a jet; the lack of a peak in the spectral energy distribution rules out advection-dominated models (based on [19].

  1. Search for Binary Black Hole Candidates from the VLBI Images of ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We have searched the core-jet pairs in the VLBI scales (< 1 kpc), from several VLBI catalogues, and found out 5 possible Binary Black Hole (BBH) candidates. We present here the search results and analyse the candidates preliminarily. We plan to study with multi-band VLBI observation. We also plan to ...

  2. Search for Binary Black Hole Candidates from the VLBI Images of ...

    Indian Academy of Sciences (India)

    Abstract. We have searched the core-jet pairs in the VLBI scales (<1 kpc), from several VLBI catalogues, and found out 5 possible Binary. Black Hole (BBH) candidates. We present here the search results and analyse the candidates preliminarily. We plan to study with multi-band. VLBI observation. We also plan to carry out ...

  3. Diverse Long-Term Variability of Five Candidate High-Mass X-Ray Binaries from Swift Burst Alert Telescope Observations

    Science.gov (United States)

    Corbet, Robin H. D.; Coley, Joel B.; Krimm, Hans A.

    2017-01-01

    We present an investigation of long-term modulation in the X-ray light curves of five little-studied candidate high-mass X-ray binaries using the Swift Burst Alert Telescope (SWIFT-BAT). IGR J14488-5942 and AX J1700.2-4220 show strong modulation at periods of 49.6 and 44 days, respectively, which are interpreted as orbital periods of Be star systems. For IGR J14488-5942, observations with the Swift X-ray Telescope show a hint of pulsations at 33.4 seconds. For AX J1700.2-4220, 54 second-pulsations were previously found with XMM-Newton. Swift J1816.7-1613 exhibits complicated behavior. The strongest peak in the power spectrum is at a period near 150 days, but this conflicts with a determination of a period of 118.5 days by La Parola et al. AX J1820.5-1434 has been proposed to exhibit modulation near 54 days, but the extended BAT observations suggest modulation at slightly longer than double this at approximately 111 days. There appears to be a long-term change in the shape of the modulation near 111 days, which may explain the apparent discrepancy. The X-ray pulsar XTE J1906+090,which was previously proposed to be a Be star system with an orbital period of approximately 30 days from pulse timing, shows peaks in the power spectrum at 81 and 173 days. The origins of these periods are unclear, although theymight be the orbital period and a superorbital period respectively. For all five sources, the long-term variability, together with the combination of orbital and proposed pulse periods, suggests that the sources contain Be starmass donors.

  4. Swift cookbook

    CERN Document Server

    Costa, Cecil

    2015-01-01

    If you are an experienced Objective-C programmer and are looking for quick solutions to many different coding tasks in Swift, then this book is for you. You are expected to have development experience, though not necessarily with Swift.

  5. Millimetre-wave emission from an intermediate-mass black hole candidate in the Milky Way

    Science.gov (United States)

    Oka, Tomoharu; Tsujimoto, Shiho; Iwata, Yuhei; Nomura, Mariko; Takekawa, Shunya

    2017-10-01

    It is widely accepted that black holes with masses greater than a million solar masses (M⊙) lurk at the centres of massive galaxies. The origins of such `supermassive' black holes (SMBHs) remain unknown1, although those of stellar-mass black holes are well understood. One possible scenario is that intermediate-mass black holes (IMBHs), which are formed by the runaway coalescence of stars in young compact star clusters2, merge at the centre of a galaxy to form a SMBH3. Although many candidates for IMBHs have been proposed, none is accepted as definitive. Recently, we discovered a peculiar molecular cloud, CO-0.40-0.22, with an extremely broad velocity width, near the centre of our Milky Way galaxy. Based on the careful analysis of gas kinematics, we concluded that a compact object with a mass of about 105M⊙ is lurking in this cloud4. Here we report the detection of a point-like continuum source as well as a compact gas clump near the centre of CO-0.40-0.22. This point-like continuum source (CO-0.40-0.22*) has a wide-band spectrum consistent with 1/500 of the Galactic SMBH (Sgr A*) in luminosity. Numerical simulations around a point-like massive object reproduce the kinematics of dense molecular gas well, which suggests that CO-0.40-0.22* is one of the most promising candidates for an intermediate-mass black hole.

  6. The Ultracompact Nature of the Black Hole Candidate X-Ray Binary 47 Tuc X9

    Science.gov (United States)

    Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, J.; hide

    2017-01-01

    47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, NuSTAR and Australia Telescope Compact Array. We find a clear 28.18+/- 0.02-min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas having a high oxygen abundance in this system, which indicates a CO white dwarf donor. We also identify reflection features in the hard X-ray spectrum, making X9 the faintest LMXB to show X-ray reflection. We detect an approx. 6.8-d modulation in the X-ray brightness by a factor of 10, in archival Chandra, Swift and ROSAT data. The simultaneous radio X-ray flux ratio is consistent with either a black hole primary or a neutron star primary, if the neutron star is a transitional millisecond pulsar. Considering the measured orbital period (with other evidence of a white dwarf donor), and the lack of transitional millisecond pulsar features in the X-ray light curve, we suggest that this could be the first ultracompact black hole X-ray binary identified in our Galaxy.

  7. Inclusion of TCAF model in XSPEC to study accretion flow dynamics around black hole candidates

    Science.gov (United States)

    Debnath, Dipak; Chakrabarti, Sandip Kumar; Mondal, Santanu

    Spectral and Temporal properties of black hole candidates can be well understood with the Chakrabarti-Titarchuk solution of two component advective flow (TCAF). This model requires two accretion rates, namely, the Keplerian disk accretion rate and the sub-Keplerian halo accretion rate, the latter being composed of a low angular momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disk rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time we are able to create a user friendly version by implementing additive Table model FITS file into GSFC/NASA's spectral analysis software package XSPEC. This enables any user to extract physical parameters of accretion flows, such as two accretion rates, shock location, shock strength etc. for any black hole candidate. Most importantly, unlike any other theoretical model, we show that TCAF is capable of predicting timing properties from spectral fits, since in TCAF, a shock is responsible for deciding spectral slopes as well as QPO frequencies.

  8. Supermassive Black Hole Binary Candidates from the Pan-STARRS1 Medium Deep Survey

    Science.gov (United States)

    Liu, Tingting; Gezari, Suvi

    2018-01-01

    Supermassive black hole binaries (SMBHBs) should be a common product of the hierarchal growth of galaxies and gravitational wave sources at nano-Hz frequencies. We have performed a systematic search in the Pan-STARRS1 Medium Deep Survey for periodically varying quasars, which are predicted manifestations of SMBHBs, and identified 26 candidates that are periodically varying on the timescale of ~300-1000 days over the 4-year baseline of MDS. We continue to monitor them with the Discovery Channel Telescope and the LCO network telescopes and thus are able to extend the baseline to 3-8 cycles and break false positive signals due to stochastic, normal quasar variability. From our imaging campaign, five candidates show persistent periodic variability and remain strong SMBHB candidates for follow-up observations. We calculate the cumulative number rate of SMBHBs and compare with previous work. We also compare the gravitational wave strain amplitudes of the candidates with the capability of pulsar timing arrays and discuss the future capabilities to detect periodic quasar and SMBHB candidates with the Large Synoptic Survey Telescope.

  9. Swift J1644+57 gone MAD: the case for dynamically important magnetic flux threading the black hole in a jetted tidal disruption event

    Science.gov (United States)

    Tchekhovskoy, Alexander; Metzger, Brian D.; Giannios, Dimitrios; Kelley, Luke Z.

    2014-01-01

    The unusual transient Swift J1644+57 likely resulted from a collimated relativistic jet, powered by the sudden onset of accretion on to a massive black hole (BH) following the tidal disruption (TD) of a star. However, several mysteries cloud the interpretation of this event, including (1) the extreme flaring and `plateau' shape of the X-ray/γ-ray light curve during the first t - ttrig ˜ 10 d after the γ-ray trigger; (2) unexpected rebrightening of the forward shock radio emission at t - ttrig ˜ months; (3) lack of obvious evidence for jet precession, despite the misalignment typically expected between the angular momentum of the accretion disc and BH; (4) recent abrupt shut-off in the jet X-ray emission at t - ttrig ˜ 1.5 yr. Here, we show that all of these seemingly disparate mysteries are naturally resolved by one assumption: the presence of strong magnetic flux Φ• threading the BH. Just after the TD event, Φ• is dynamically weak relative to the high rate of fall-back accretion dot{M}, such that the accretion disc (jet) freely precesses about the BH axis = our line of sight. As dot{M} decreases, however, Φ• becomes dynamically important, leading to a state of `magnetically arrested disk' (MAD). MAD naturally aligns the jet with the BH spin, but only after an extended phase of violent rearrangement (jet wobbling), which in Swift J1644+57 starts a few days before the γ-ray trigger and explains the erratic early light curve. Indeed, the entire X-ray light curve can be fitted to the predicted power-law decay dot{M} ∝ t^{-α } (α ≃ 5/3 - 2.2) if the TD occurred a few weeks prior to the γ-ray trigger. Jet energy directed away from the line of sight, either prior to the trigger or during the jet alignment process, eventually manifests as the observed radio rebrightening, similar to an off-axis (orphan) γ-ray burst afterglow. As suggested recently, the late X-ray shut-off occurs when the disc transitions to a geometrically thin (jetless) state once

  10. Characterization of few transient black hole candidates during their X-ray outbursts with TCAF Solution

    Science.gov (United States)

    Debnath, Dipak; Mondal, S.; Chakrabarti, S. K.; Jana, A.; Molla, A. A.; Chatterjee, D.

    The theoretical concept of Chakrabarti-Titarchuk two Component Advective Flow (TCAF) model was introduced around two decades ago in mid-90s. Recently after the inclusion of TCAF model into XSPEC as an additive table model, we find that it is quite capable to fit spectra from different phases of few transient black hole candidates (TBHCs) during their outbursts. This quite agrees with our theoretical understanding. Here, a brief summary of our recent studies of spectral and temporal properties of few TBHCs during their X-ray outbursts with TCAF will be discussed.

  11. NuSTAR AND Swift Observations of the Very High State in GX 339-4: Weighing the Black Hole With X-Rays

    Science.gov (United States)

    Parker, M. L.; Tomsick, J. A.; Kennea, J. A.; Miller, J. M.; Harrison, F. A.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; hide

    2016-01-01

    We present results from spectral fitting of the very high state of GX339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0.95+0.08/-0.02 and inclination of 30deg +/- 1deg (statistical errors). These values agree well with previous results from reflection modeling. With the exceptional sensitivity of NuSTAR at the high-energy side of the disk spectrum, we are able to constrain multiple physical parameters simultaneously using continuum fitting. By using the constraints from reflection as input for the continuum fitting method, we invert the conventional fitting procedure to estimate the mass and distance of GX 339-4 using just the X-ray spectrum, finding a mass of 9.0+1.6/-1.2 Stellar Mass and distance of 8.4 +/- 0.9 kpc (statistical errors).

  12. A RADIO-SELECTED BLACK HOLE X-RAY BINARY CANDIDATE IN THE MILKY WAY GLOBULAR CLUSTER M62

    Energy Technology Data Exchange (ETDEWEB)

    Chomiuk, Laura; Ransom, Scott [National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA (United States); Strader, Jay [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Maccarone, Thomas J. [Department of Physics, Texas Tech University, Box 41051, Lubbock, TX 79409-1051 (United States); Miller-Jones, James C. A. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Heinke, Craig [Department of Physics, University of Alberta, 4-183 CCIS, Edmonton, AB T6G 2E1 (Canada); Noyola, Eva [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM), A. P. 70-264, 04510 (Mexico); Seth, Anil C., E-mail: chomiuk@pa.msu.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)

    2013-11-01

    We report the discovery of a candidate stellar-mass black hole in the Milky Way globular cluster M62. We detected the black hole candidate, which we call M62-VLA1, in the core of the cluster using deep radio continuum imaging from the Karl G. Jansky Very Large Array. M62-VLA1 is a faint source with a flux density of 18.7 ± 1.9 μJy at 6.2 GHz and a flat radio spectrum (α = –0.24 ± 0.42, for S{sub ν} = ν{sup α}). M62 is the second Milky Way cluster with a candidate stellar-mass black hole; unlike the two candidate black holes previously found in the cluster M22, M62-VLA1 is associated with a Chandra X-ray source, supporting its identification as a black hole X-ray binary. Measurements of its radio and X-ray luminosity, while not simultaneous, place M62-VLA1 squarely on the well-established radio-X-ray correlation for stellar-mass black holes. In archival Hubble Space Telescope imaging, M62-VLA1 is coincident with a star near the lower red giant branch. This possible optical counterpart shows a blue excess, Hα emission, and optical variability. The radio, X-ray, and optical properties of M62-VLA1 are very similar to those for V404 Cyg, one of the best-studied quiescent stellar-mass black holes. We cannot yet rule out alternative scenarios for the radio source, such as a flaring neutron star or background galaxy; future observations are necessary to determine whether M62-VLA1 is indeed an accreting stellar-mass black hole.

  13. The Faint "Heartbeats" of IGR J17091-3624: An Exceptional Black Hole Candidate

    Science.gov (United States)

    Altamirano, D.; Belloni, T.; Linares, M.; VanDerKlis, M.; Wunands, R.; Curran, P. A.; Kalamkar, M.; Stiele, H.; Motta, S.; Munoz-Darias, T.; hide

    2011-01-01

    We report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR Jl7091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that JGR J17091-3624 shows the nu, rho, alpha, lambda, Beta, and mu classes as well as quiet periods which resemble the chi class, all occurring at 2-60 keY count rate levels which can be 10-50 times lower than observed in GRS 1915+\\05. The so-called rho class "heartbeats" occur as fast as every few seconds and as slow as approx 100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+\\05. However, while GRS 1915+105 traverses this loop clockwise, IGR Jl7091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR Il7091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known( <3 solar M).

  14. Testing the existence of regions of stable orbits at small radii around black hole candidates

    CERN Document Server

    Bambi, Cosimo

    2013-01-01

    Black hole candidates in X-ray binary systems and at the centers of galaxies are expected to be the Kerr black holes of General Relativity, but the actual nature of these objects has still to be verified. In this paper, we consider the possibility they are exotic compact objects and we describe their exterior gravitational field with a subclass of the Manko-Novikov metrics, which are exact solutions of the vacuum Einstein's equations and can describe the spacetime geometry around bodies with arbitrary mass-multipole moments. We point out that around a Manko-Novikov object there may exist many disconnected non-plunging regions at small radii, with no counterpart in the Kerr background, and that their existence may be tested. For instance, in the presence of an accretion disk, they may be filled by the accreting gas, forming a ring structure that might remind the rings of Saturn. We suggest that the existence of these regions may have a clear observational signature in the waveform of the gravitational radiatio...

  15. Study of the spectral and the temporal properties of few black hole candidates with TCAF model

    Science.gov (United States)

    Mondal, Santanu; Debnath, Dipak; Chakrabarti, Sandip Kumar

    We study spectral and temporal properties of outbursting black hole candidates (BHCs) using Two Component Advective Flow (TCAF) model in XSPEC as a local additive table model. Evolution of spectral and temporal properties of BHCs can easily be explained with spectral analysis using TCAF. From TCAF model fit of black hole spectra one can extract two types of flow rates (Keplerian and sub-Keplerian rates) and shock parameters (location and strength), which give new insight into the problem of accretion dynamics. Depending upon accretion rate ratio (ARR) and nature of QPOs (if present) we can classify total outburst phases of transient BHCs in different spectral states. This classification qualitatively match with the classifications based on spectral properties alone. However, in our process, use the physical quantities, such as accretion rates gave a complete, meaning of what exactly happens in a state transition. We also compare TCAF model fitted spectral results with combined disk black body and power-law model fitted results, which almost matches. In our study, evolution of quasi periodic oscillations (QPOs) also explained from the movement of shock location. It is also clear from the analysis that the rising and declining phases may not retrace the same path always and form a hysteresis loop.

  16. Characterization of few transient black hole candidates with TCAF model during their outbursts

    Science.gov (United States)

    Debnath, Dipak; Chakrabarti, Sandip Kumar; Mondal, Santanu

    Galactic transient black hole candidates (BHCs) are very interesting objects to study in X-rays because they exhibit rapid evolutions in their temporal and spectral properties during outbursts, which are strongly correlated with each other. There are a large number of phenomenological and theoretical models in the literature which claim to explain physics of accretion around a black hole. However, two Component Advective Flow (TCAF) model of Chakrabarti & Titarchuk (1995) based on viscous transonic accretion flows appears to be able to explain both the spectral and temporal properties very successfully. We have included TCAF as an additive table model in GSFC/NASA spectral analysis package XSPEC. From our spectral fit, one can directly extract flow parameters, such as two types of accretion (Keplerian disk and sub-Keplerian halo) rates and shock parameters (location and strength of the shock). From shock parameters, one can predict frequency of primary dominating QPOs. Based on a comparison of halo to disk accretion rate ratio (ARR) along with the presence or absence of quasi-periodic oscillations (QPOs), we are able to provide a physical understanding of the classification of the entire outburst phase of the BHCs into different spectral states. In general, transient BHCs, are found to exhibit four different spectral states during their outbursts. These are : hard, hard-intermediate, soft-intermediate, and soft. They form a hysteresis loop while evolving in the sequence: hard -> hard-intermediate -> soft-intermediate -> soft -> soft-intermediate -> hard-intermediate -> hard.

  17. Resolved, expanding jets in the Galactic black hole candidate XTE J1908+094

    Science.gov (United States)

    Rushton, A. P.; Miller-Jones, J. C. A.; Curran, P. A.; Sivakoff, G. R.; Rupen, M. P.; Paragi, Z.; Spencer, R. E.; Yang, J.; Altamirano, D.; Belloni, T.; Fender, R. P.; Krimm, H. A.; Maitra, D.; Migliari, S.; Russell, D. M.; Russell, T. D.; Soria, R.; Tudose, V.

    2017-07-01

    Black hole X-ray binaries undergo occasional outbursts caused by changing inner accretion flows. Here we report high angular resolution radio observations of the 2013 outburst of the black hole candidate X-ray binary system XTE J1908+094, using data from the Very Long Baseline Array and European VLBI Network. We show that following a hard-to-soft state transition, we detect moving jet knots that appear asymmetric in morphology and brightness, and expand to become laterally resolved as they move away from the core, along an axis aligned approximately -11° east of north. We initially see only the southern component, whose evolution gives rise to a 15-mJy radio flare and generates the observed radio polarization. This fades and becomes resolved out after 4 days, after which a second component appears to the north, moving in the opposite direction. From the timing of the appearance of the knots relative to the X-ray state transition, a 90° swing of the inferred magnetic field orientation, the asymmetric appearance of the knots, their complex and evolving morphology, and their low speeds, we interpret the knots as working surfaces where the jets impact the surrounding medium. This would imply a substantially denser environment surrounding XTE J1908+094 than has been inferred to exist around the microquasar sources GRS 1915+105 and GRO J1655-40.

  18. Swift essentials

    CERN Document Server

    Blewitt, Alex

    2014-01-01

    Whether you are a seasoned Objective-C developer or new to the Xcode platform, Swift Essentials will provide you with all you need to know to get started with the language. Prior experience with iOS development is not necessary, but will be helpful to get the most out of the book.

  19. A Catalog Sample of Low-mass Galaxies Observed in X-Rays with Central Candidate Black Holes

    Science.gov (United States)

    Nucita, A. A.; Manni, L.; De Paolis, F.; Giordano, M.; Ingrosso, G.

    2017-03-01

    We present a sample of X-ray-selected candidate black holes in 51 low-mass galaxies with z ≤ 0.055 and masses up to 1010 M ⊙ obtained by cross-correlating the NASA-SLOAN Atlas with the 3XMM catalog. We have also searched in the available catalogs for radio counterparts of the black hole candidates and find that 19 of the previously selected sources also have a radio counterpart. Our results show that about 37% of the galaxies of our sample host an X-ray source (associated with a radio counterpart) spatially coincident with the galaxy center, in agreement with other recent works. For these nuclear sources, the X-ray/radio fundamental plane relation allows one to estimate the mass of the (central) candidate black holes, which are in the range of 104-2 × 108 M ⊙ (with a median value of ≃3 × 107 M ⊙ and eight candidates having masses below 107 M ⊙). This result, while suggesting that X-ray emitting black holes in low-mass galaxies may have had a key role in the evolution of such systems, makes it even more urgent to explain how such massive objects formed in galaxies. Of course, dedicated follow-up observations both in the X-ray and radio bands, as well as in the optical, are necessary in order to confirm our results.

  20. The host galaxy of the gravitational wave recoiling black hole candidate 3C186

    Science.gov (United States)

    Chiaberge, Marco

    2017-08-01

    We discovered a gravitational wave (GW) recoiling black hole (BH) candidate in our HST WFC3 snapshot images of the radio-loud QSO 3C186. These events are expected to happen as a result of BH-BH mergers. This extremely energetic phenomenon leads to the production of an intense field of GWs, which in most cases are emitted anisotropically. As a result, the merged black hole may receive a kick and be displaced from the center of the host galaxy with velocities that can be as high as 4000 km/s. Depending on the relative orientation of the kick with respect to the line-of-sight, if the BH is active we expect to observe an offset QSO. Furthermore, the broad lines may be offset with respect to the narrow lines, which are emitted in the frame of the host. 3C186 shows all of the predicted observational features of a such an event. Spectra show offsets between narrow and broad emission lines of 2100km/s, and our HST image clearly shows that the QSO is offset by 1.3 with respect to the isophotal center of the host galaxy. Scenarios alternative to the GW kick as the origin for the observed features are unlikely, but still viable. Only HST allows us to obtain spatially resolved information, high sensitivity and stable PSF to better investigate the host galaxy properties. We will use ACS and WFC3 to obtain deep images and study the morphology of the host galaxy. We will unambiguously establish whether the host galaxy of 3C186 underwent a major merger and we will be able to set accurate constraints on the age of the merger. The proposed observations will have a tremendous impact on our knowledge of supermassive BH mergers and the associated emission of gravitational waves.

  1. CHANDRA IDENTIFICATION OF 26 NEW BLACK HOLE CANDIDATES IN THE CENTRAL REGION OF M31

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M. R.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics (CFA), Cambridge, MA 02138 (United States)

    2013-06-20

    We have previously identified 10 M31 black hole candidates (BHCs) in M31 from their X-ray properties alone. They exhibit ''hard state'' emission spectra that are seen at luminosities {approx}<10% Eddington in X-ray binaries (XBs) containing a neutron star (NS) or black hole, at luminosities that significantly exceed the NS threshold. Nine of these are associated with globular clusters (GCs); hence, these are most likely low mass X-ray binaries; eight are included in this survey. We have recently discovered that analysis of the long term 0.5-4.5 keV variability of XBs via structure functions allows us to separate XBs from active galactic nuclei, even though the emission spectra are often similar; this has enabled us to search for BHCs outside of GCs. We have identified 26 new BHCs (12 strong, 14 plausible) within 20' of the M31 nucleus (M31*), using 152 Chandra observations spaced over {approx}13 yr; some of our classifications were enhanced with XMM-Newton observations. Of these, seven appear within 100'' of M31*; this supports the theory suggesting that this region experiences enhanced XB production via dynamical processes similar to those seen in GCs. We have found a parameter space where our BHCs are separated from Galactic NS binaries: we show that modeling a simulated hard state spectrum with a disk blackbody + blackbody model yields parameters that lie outside the space occupied by NS binaries that are modeled this way. The probability that our BHCs all lie within the NS parameter space is {approx}3 Multiplication-Sign 10{sup -29}.

  2. The evolution of the X-ray phase lags during the outbursts of the black hole candidate GX 339-4

    NARCIS (Netherlands)

    Altamirano, Diego; Méndez, Mariano

    2015-01-01

    Owing to the frequency and reproducibility of its outbursts, the black hole candidate GX 339-4 has become the standard against which the outbursts of other black hole candidate are matched up. Here we present the first systematic study of the evolution of the X-ray lags of the broad-band variability

  3. Monsters on the move: Confirming gravitational wave recoiling supermassive black hole candidates

    Science.gov (United States)

    Robinson, Andrew

    2017-08-01

    There is compelling evidence that supermassive black holes (SMBH) reside at the centers of all large galaxies and are the gravitational 'engines' of Active Galactic Nuclei (AGN). Mergers between galaxies are thought to have played a fundamental role in the growth and evolution of the largest galaxies in the nearby universe. Galaxy mergers lead to the formation of an SMBH binary, which eventually coalescences through the emission of gravitational waves and receives a recoil kick ( several 1000km/s). This recoil in turn causes the merged SMBH to oscillate ( 1Gyr) in the gravitational potential well of the host galaxy. During this time, the recoiling SMBH may be observed as a 'displaced' AGN. These events are a strong test of gravitational physics and the merger frequency of binary SMBH. Due to the long damping time of the post recoil oscillations, displacements 10-100pc may be expected even in nearby elliptical galaxies and can be measured as spatial offsets of AGN in high resolution optical or infrared images. In a preliminary study of 96 early type galaxies using archival HST/WFPC2 images we have identified 18 candidates that show a significant displacement between the SMBH (traced by the AGN) and the photocenter of the host galaxy, determined by isophotal analysis. However, it is necessary to confirm these displacements using IR images since diffuse galaxy scale and nuclear dust structures are common. Here we propose to obtain WFC3/IR F110W and F160W images of 6 of the 18 candidates for which no IR images are available in the HST archive. These observations will allow us to both confirm and improve the accuracy of the measured displacements.

  4. On the Nature of QPO Phase Lags in Black Hole Candidates

    Science.gov (United States)

    Shaposhnikov, Nikolai

    2012-01-01

    Observations of quasi-periodic oscillations (QPOs) in X-ray binaries hold a key to understanding many aspects of these enigmatic systems. Complex appearance of the Fourier phase lags related to QPOs is one of the most puzzling observational effects in accreting black holes. In this Letter we show that QPO properties, including phase lags, can be explained in a framework of a simple scenario, where the oscillating media provides a feedback on the emerging spectrum. We demonstrate that the QPO waveform is presented by the product of a perturbation and a time delayed response factors, where the response is energy dependent. The essential property of this effect is its non-linear and multiplicative nature. Our multiplicative reverberation model successfully describes the QPO components in energy dependent power spectra as well as the appearance of the phase lags between signal in different energy bands. We apply our model to QPOs observed by Rossi X-ray Timing Explorer in BH candidate XTE J1550-564. We briefly discuss the implications of the observed energy dependence of the QPO reverberation times and amplitudes to the nature of the power law spectral component and its variability.

  5. The long-term optical evolution of the black hole candidate MAXI J1659-152

    Science.gov (United States)

    Corral-Santana, Jesús M.; Torres, Manuel A. P.; Shahbaz, Tariq; Bartlett, Elizabeth S.; Russell, David M.; Kong, Albert K. H.; Casares, Jorge; Muñoz-Darias, Teodoro; Bauer, Franz E.; Homan, Jeroen; Jonker, Peter G.; Mata Sánchez, Daniel; Wevers, Thomas; Rodríguez-Gil, Pablo; Lewis, Fraser; Schreuder, Laurien

    2018-03-01

    We present 5 yr of optical and infrared data of the black hole candidate MAXI J1659-152 covering its 2010 outburst, decay, and quiescence. Combining optical data taken during the outburst decay, we obtain an orbital period of 2.414 ± 0.005 h, in perfect agreement with the value previously measured from X-ray dips. In addition, we detect a clear H α excess in MAXI J1659-152 with data taken during the outburst decay. We also detect a single hump modulation most likely produced by irradiation. Assuming that the maximum occurs at orbital phase 0.5, we constrain the phase of the X-ray dips to be ˜0.65. We also detect the quiescent optical counterpart at r΄ = 24.20 ± 0.08, I = 23.32 ± 0.02, and H = 20.7 ± 0.1. These magnitudes provide colour indices implying an M2-M5 donor star assuming 60 per cent contribution from a disc component in the r΄ band.

  6. A candidate sub-parsec binary black hole in the Seyfert galaxy NGC 7674

    Science.gov (United States)

    Kharb, P.; Lal, D. V.; Merritt, D.

    2017-10-01

    The existence of binary supermassive black holes (SBHs) is predicted by models of hierarchical galaxy formation. To date, only a single binary SBH has been imaged, at a projected separation of 7.3 pc. Here, we report the detection of a candidate dual SBH with projected separation of 0.35 pc in the gas-rich interacting spiral galaxy NGC 7674 (Mrk 533). This peculiar Seyfert galaxy possesses a roughly 0.7 kpc Z-shaped radio jet. The leading model for the formation of such sources postulates the presence of an uncoalesced binary SBH created during the infall of a satellite galaxy. Using very long baseline interferometry, we imaged the central region of Mrk 533 at radio frequencies of 2, 5, 8 and 15 GHz. Two, possibly inverted-spectrum, radio cores were detected at 15 GHz only. The 8-15 GHz spectral indices of the two cores were ≥-0.33 and ≥-0.38 (±30%), consistent with accreting SBHs. We derived a jet speed of around 0.28c from multi-epoch parsec-scale data of the hotspot region and a source age of ≥ 8.2 × 103 years.

  7. Dynamics of massive black holes as a possible candidate of Galactic dark matter

    Science.gov (United States)

    Xu, Guohong; Ostriker, Jeremiah P.

    1994-01-01

    If the dark halo of the Galaxy is comprised of massive black holes (MBHs), then those within approximately 1 kpc will spiral to the center, where they will interact with one another, forming binaries which contract, owing to further dynamical friction, and then possibly merge to become more massive objects by emission of gravitational radiation. If successive mergers would invariably lead, as has been proposed by various authors, to the formation of a very massive nucleus of 10(exp 8) solar mass, then the idea of MBHs as a dark matter candidate could be excluded on observational grounds, since the observed limit (or value) for a Galactic central black hole is approximately 10(exp 6.5) solar mass. But, if successive mergers are delayed or prevented by other processes, such as the gravitational slingshot or rocket effect of gravitational radiation, then a large mass accumulation will not occur. In order to resolve this issue, we perform detailed N-body simulations using a modfied Aarseth code to explore the dynamical behavior of the MBHs, and we find that for a 'best estimate' model of the Galaxy a runaway does not occur. The code treates the MBHs as subject to the primary gravitational forces of one another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to dynamical friction and gravitational radiation. Instead of a runaway, three-body interactions between hard binaries and single MBHs eject massive objects before accumulation of more than a few units, so that typically the center will contain zero, one, or two MBHs. We study how the situation depends in detail on the mass per MBH, the rotation of the halo, the mass distribution within the Galaxy, and other parameters. A runaway will most sensitively depend on the ratio of initial (spheroid/halo) central mass densities and secondarily on the typical values

  8. Fifty M31 black hole candidates identified by Chandra and XMM-Newton

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, R.; Garcia, M. R.; Primini, F.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2014-08-10

    Over approximately the last five years, we have identified ∼35 black hole candidates (BHCs) in M31 from their X-ray spectra. Our BHCs exhibited 0.3-10 keV spectra consistent with the X-ray binary (XB) hard state at luminosities that are above the upper limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk blackbody + blackbody model for comparison with bright NS XBs, we found that the BHCs inhabited a different parameter space than the NS XBs. However, BH XBs may also exhibit a thermally dominated (TD) state that has never been seen in NS XBs; this TD state is most often observed in X-ray transients. We examined the ∼50 X-ray transients in our Chandra survey of M31 and found 13 with spectra suitable for analysis. We also examined two BHCs outside the field of view of our survey in the globular clusters B045 and B375. We have 42 strong BHCs and 8 plausible BHCs that may benefit from further observation. Of our 15 BHCs in globular clusters, 12 differ from NS spectra by >5σ. Due to improvements in our analysis, we have upgraded 10 previously identified plausible BHCs to strong BHCs. The mean maximum duty cycle of the 33 X-ray transients within 6' of M31* is 0.13; we estimate that >40% of the XBs in this region contain BH accretors. Remarkably, we estimate that BHCs contribute >90% of those XBs >10{sup 38} erg s{sup –1}.

  9. MAXI J1659-152: The shortest orbital period black-hole transient in outburst

    DEFF Research Database (Denmark)

    Kuulkers, E.; Kouveliotou, C.; Belloni, T.

    2013-01-01

    MAXI J1659−152 is a bright X-ray transient black-hole candidate binary system discovered in September 2010. We report here on MAXI, RXTE, Swift, and XMM-Newton observations during its 2010/2011 outburst. We find that during the first one and a half week of the outburst the X-ray light curves disp...

  10. Relativistic boost as the cause of periodicity in a massive black-hole binary candidate.

    Science.gov (United States)

    D'Orazio, Daniel J; Haiman, Zoltán; Schiminovich, David

    2015-09-17

    Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries, most recently in PG 1302-102, which has a short rest-frame optical period of four years (ref. 6). If the orbital period of the black-hole binary matches this value, then for the range of estimated black-hole masses, the components would be separated by 0.007-0.017 parsecs, implying relativistic orbital speeds. There has been much debate over whether black-hole orbits could be smaller than one parsec (ref. 7). Here we report that the amplitude and the sinusoid-like shape of the variability of the light curve of PG 1302-102 can be fitted by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a two to three times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival ultraviolet data. Follow-up ultraviolet and optical observations in the next few years can further test this prediction and confirm the existence of a binary black hole in the relativistic regime.

  11. Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47.

    Science.gov (United States)

    Trigo, María Díaz; Miller-Jones, James C A; Migliari, Simone; Broderick, Jess W; Tzioumis, Tasso

    2013-12-12

    Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and, hence, the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. Energetic considerations and circular-polarization measurements have provided conflicting circumstantial evidence for the presence or absence of baryons in jets, and the only system in which they have been unequivocally detected is the peculiar X-ray binary SS 433 (refs 4, 5). Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black-hole candidate X-ray binary, 4U 1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise from baryonic matter in a jet travelling at approximately two-thirds the speed of light, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the accretion disk than by the spin of the black hole, and if the baryons can be accelerated to relativistic speeds, the jets should be strong sources of γ-rays and neutrino emission.

  12. A detached stellar-mass black hole candidate in the globular cluster NGC 3201

    Science.gov (United States)

    Giesers, Benjamin; Dreizler, Stefan; Husser, Tim-Oliver; Kamann, Sebastian; Anglada Escudé, Guillem; Brinchmann, Jarle; Carollo, C. Marcella; Roth, Martin M.; Weilbacher, Peter M.; Wisotzki, Lutz

    2018-03-01

    As part of our massive spectroscopic survey of 25 Galactic globular clusters with MUSE, we performed multiple epoch observations of NGC 3201 with the aim of constraining the binary fraction. In this cluster, we found one curious star at the main-sequence turn-off with radial velocity variations of the order of 100 km s- 1, indicating the membership to a binary system with an unseen component since no other variations appear in the spectra. Using an adapted variant of the generalized Lomb-Scargle periodogram, we could calculate the orbital parameters and found the companion to be a detached stellar-mass black hole with a minimum mass of 4.36 ± 0.41 M⊙. The result is an important constraint for binary and black hole evolution models in globular clusters as well as in the context of gravitational wave sources.

  13. The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9

    Science.gov (United States)

    Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, Jay; Garcia, Javier A.; Kallman, Timothy

    2017-05-01

    47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio/X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, NuSTAR and Australia Telescope Compact Array. We find a clear 28.18 ± 0.02-min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas having a high oxygen abundance in this system, which indicates a C/O white dwarf donor. We also identify reflection features in the hard X-ray spectrum, making X9 the faintest LMXB to show X-ray reflection. We detect an ˜6.8-d modulation in the X-ray brightness by a factor of 10, in archival Chandra, Swiftand ROSAT data. The simultaneous radio/X-ray flux ratio is consistent with either a black hole primary or a neutron star primary, if the neutron star is a transitional millisecond pulsar. Considering the measured orbital period (with other evidence of a white dwarf donor), and the lack of transitional millisecond pulsar features in the X-ray light curve, we suggest that this could be the first ultracompact black hole X-ray binary identified in our Galaxy.

  14. Swift for dummies

    CERN Document Server

    Feiler, Jesse

    2015-01-01

    Get up and running with Swift-swiftly Brimming with expert advice and easy-to-follow instructions,Swift For Dummies shows new and existing programmers how toquickly port existing Objective-C applications into Swift and getinto the swing of the new language like a pro. Designed from theground up to be a simpler programming language, it's never beeneasier to get started creating apps for the iPhone or iPad, orapplications for Mac OS X. Inside the book, you'll find out how to set up Xcode for a newSwift application, use operators, objects, and data types, andcontrol program flow with conditiona

  15. Chasing the observational signatures of seed black holes at z > 7: candidate observability

    Science.gov (United States)

    Valiante, Rosa; Schneider, Raffaella; Zappacosta, Luca; Graziani, Luca; Pezzulli, Edwige; Volonteri, Marta

    2018-01-01

    Observing the light emitted by the first accreting black holes (BHs) would dramatically improve our understanding of the formation of quasars at z > 6, possibly unveiling the nature of their supermassive black hole (SMBH) seeds. In previous works we explored the relative role of the two main competing BH seed formation channels, Population III remnants (low-mass seeds) and direct collapse BHs (high-mass seeds), investigating the properties of their host galaxies in a cosmological context. Building on this analysis, we predict here the spectral energy distribution and observational features of low- and high-mass BH seeds selected among the progenitors of a z ˜ 6 SMBH. We derive the processed emission from both accreting BHs and stars by using the photo-ionization code Cloudy, accounting for the evolution of metallicity and dust-to-gas mass ratio in the interstellar medium of the host galaxies, as predicted by the cosmological data-constrained model GAMETE/QSODUST. We show how future missions like JWST and ATHENA will be able to detect the light coming from SMBH progenitors already at z ˜ 16. We build upon previous complementary studies and propose a method based on the combined analysis of near infrared (NIR) colors, IR excess (IRX) and UV continuum slopes (i.e. color-color and IRX-β diagrams) to distinguish growing seed BH host galaxies from starburst-dominated systems in JWST surveys. Sources selected through this criterion would be the best target for follow-up X-ray observations.

  16. VLBA 24 and 43 GHz observations of massive binary black hole candidate PKS 1155 + 251

    Science.gov (United States)

    Yang, Xiaolong; Liu, Xiang; Yang, Jun; Mi, Ligong; Cui, Lang; An, Tao; Hong, Xiaoyu; Ho, Luis C.

    2017-10-01

    PKS 1155+251 is a radio-loud quasar source at z = 0.203. Observations using very long baseline interferometry (VLBI) at ∼2, 5, 8 and 15 GHz show that the structure of the radio source is quite complicated on parsec scales and that the outer hotspots are apparently undergoing a significant contraction. Because these results cannot be fully explained based on the compact symmetric object (CSO) scenario with a radio core located between the northern and southern complexes, we made observations with the Very Long Baseline Array (VLBA) at 24 and 43 GHz to search for compact substructures and alternative interpretations. The results show that the radio core revealed in the previous VLBI observations remains compact with a flat spectrum in our sub-milli-arcsecond-resolution images; the northern lobe emission becomes faint at 24 GHz and is mostly resolving out at 43 GHz; the southern complex is more bright but has been resolved into the brightest southern-end (S1) and jet or tail alike components westwards. Explaining the southern components aligned westward with a standard CSO scenario alone remains a challenge. As for the flatter spectral index of the southern-end component S1 between 24 and 43 GHz in our observations and the significant 15 GHz VLBA flux variability of S1, an alternative scenario is that the southern complex may be powered by a secondary black hole residing at S1. But more sensitive and high-resolution VLBI monitoring is required to discriminate the CSO and the binary black hole scenarios.

  17. THE FAINT 'HEARTBEATS' OF IGR J17091-3624: AN EXCEPTIONAL BLACK HOLE CANDIDATE

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano, D.; Van der Klis, M.; Wijnands, R.; Kalamkar, M. [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH, Amsterdam (Netherlands); Belloni, T.; Stiele, H.; Motta, S.; Munoz-Darias, T. [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Linares, M. [Massachusetts Institute of Technology-Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Curran, P. A. [Laboratoire AIM, CEA DSM/IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Casella, P. [School of Physics and Astronomy, University of Southampton, Southampton, Hampshire, SO17 1BJ (United Kingdom); Krimm, H., E-mail: d.altamirano@uva.nl [CRESST and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2011-12-15

    We report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR J17091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that IGR J17091-3624 shows the {nu}, {rho}, {alpha}, {lambda}, {beta}, and {mu} classes as well as quiet periods which resemble the {chi} class, all occurring at 2-60 keV count rate levels which can be 10-50 times lower than observed in GRS 1915+105. The so-called {rho} class 'heartbeats' occur as fast as every few seconds and as slow as {approx}100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+105. However, while GRS 1915+105 traverses this loop clockwise, IGR J17091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR J17091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known (<3 M{sub Sun }).

  18. Chandra Survey of Nearby Galaxies: A Significant Population of Candidate Central Black Holes in Late-type Galaxies

    Science.gov (United States)

    She, Rui; Ho, Luis C.; Feng, Hua

    2017-06-01

    Based on the Chandra data archive as of 2016 March, we have identified 314 candidate active galactic nuclei in 719 galaxies located closer than 50 Mpc, among them late-type galaxies (Hubble types Sc and later) that previously had been classified from optical observations as containing star-forming (H II) nuclei. These late-type galaxies comprise a valuable subsample to search for low-mass (≲ {10}6 {M}⊙ ) central black holes. For the sample as a whole, the overall dependence of the fraction of active nuclei on galaxy type and nuclear spectral classification is consistent with previous results based on optical surveys. We detect 51 X-ray cores among the 163 H II nuclei and estimate that, very conservatively, ˜74% of them with luminosities above 1038 {erg} {{{s}}}-1 are not contaminated by X-ray binaries; the fraction increases to ˜92% for X-ray cores with a luminosity of 1039 {erg} {{{s}}}-1 or higher. This allows us to estimate a black hole occupation fraction of ≳ 21% in these late-type galaxies, many of which are bulgeless.

  19. Estimation of the mass of the black hole candidate MAXI J1659-152 using TCAF and POS models

    Science.gov (United States)

    Molla, Aslam Ali; Debnath, Dipak; Chakrabarti, Sandip K.; Mondal, S.; Jana, A.

    2016-08-01

    The Galactic transient black hole candidate (BHC) MAXI J1659-152 exhibited temporal and spectral evolution during its very first X-ray outburst (2010) after its discovery on 2010 September 25. Our recent studies of a few transient BHCs, including MAXI J1659-152, using the Chakrabarti-Titarchuk two-component advective flow (TCAF) solution as an additive table local model in the XSPEC software revealed details of the accretion-flow dynamics around the black holes. The TCAF model-fitted normalization (N) comes out to be almost constant throughout the entire outburst, consisting of several spectral states. We introduce two independent methods to determine the mass (MBH) of the BHC: namely (i) keeping the TCAF fitted normalization parameter in a narrow range and (ii) studying the evolution of the quasi-periodic oscillation frequency (νQPO) with time, fitting with the propagating oscillatory shock (POS) model. The predicted mass ranges of the source with these two methods are 4.7-7.8 M⊙ and 5.1-7.4 M⊙, respectively. Combining the results of these two methods, we obtain a most probable mass range of the source of 4.7-7.8 M⊙ or 6^{+1.8}_{-1.3} M_{⊙}.

  20. Testing the Kerr nature of black hole candidates using iron line reverberation mapping in the Cardoso-Pani-Rico framework

    Science.gov (United States)

    Jiang, Jiachen; Bambi, Cosimo; Steiner, James F.

    2016-06-01

    The iron K α line commonly observed in the x-ray spectrum of black hole candidates is produced by x-ray fluorescence of the inner accretion disk. This line can potentially be quite a powerful tool to probe the spacetime geometry around these objects and test the Kerr black hole hypothesis. In a previous paper, we studied the ability to constrain possible deviations from the Kerr solution from the standard time-integrated iron line spectrum within the Cardoso-Pani-Rico framework. In the present work, we expand on that study and consider iron line reverberation mapping in the Cardoso-Pani-Rico framework. That is, we consider the time evolution of the iron line profile in response to fluctuations in the x-ray primary source. Our simulations clearly show that the time information in reverberation mapping can better constrain the background metric than the time-integrated approach, and this is true, notably, for the deformation parameter ɛ3r, which is only weakly informed by a time-integrated observation.

  1. Chasing the observational signatures of seed black holes at z > 7: candidate statistics

    Science.gov (United States)

    Valiante, Rosa; Schneider, Raffaella; Graziani, Luca; Zappacosta, Luca

    2018-03-01

    Supermassive black holes (SMBHs) of 109-1010 M⊙ were already in place ˜13 Gyr ago, at z > 6. Super-Eddington growth of low-mass BH seeds (˜100 M⊙) or less extreme accretion on to˜105 M⊙ seeds have been recently considered as the main viable routes to these SMBHs. Here, we study the statistics of these SMBH progenitors at z ˜ 6. The growth of low- and high-mass seeds and their host galaxies are consistently followed using the cosmological data constrained model GAMETE/QSODUST, which reproduces the observed properties of high-z quasars, like SDSS J1148+5251. We show that both seed formation channels can be in action over a similar redshift range 15 < z < 18 and are found in dark matter haloes with comparable mass, ˜5 × 107 M⊙. However, as long as the systems evolve in isolation (i.e. no mergers occur), noticeable differences in their properties emerge: At z ≥ 10 galaxies hosting high-mass seeds have smaller stellar mass and metallicity, the BHs accrete gas at higher rates and star formation proceeds less efficiently than in low-mass seeds hosts. At z < 10 these differences are progressively erased, as the systems experience minor or major mergers and every trace of the BH origin gets lost.

  2. Possible Range of Viscosity Parameters to Trigger Black Hole Candidates to Exhibit Different States of Outbursts

    Science.gov (United States)

    Mondal, Santanu; Chakrabarti, Sandip K.; Nagarkoti, Shreeram; Arévalo, Patricia

    2017-11-01

    In a two component advective flow around a compact object, a high-viscosity Keplerian disk is flanked by a low angular momentum and low-viscosity flow that forms a centrifugal, pressure-supported shock wave close to the black hole. The post-shock region that behaves like a Compton cloud becomes progressively smaller during the outburst as the spectra change from the hard state (HS) to the soft state (SS), in order to satisfy the Rankine–Hugoniot relation in the presence of cooling. The resonance oscillation of the shock wave that causes low-frequency quasi-periodic oscillations (QPOs) also allows us to obtain the shock location from each observed QPO frequency. Applying the theory of transonic flow, along with Compton cooling and viscosity, we obtain the viscosity parameter {α }{SK} required for the shock to form at those places in the low-Keplerian component. When we compare the evolution of {α }{SK} for each outburst, we arrive at a major conclusion: in each source, the advective flow component typically requires an exactly similar value of {α }{SK} when transiting from one spectral state to another (e.g., from HS to SS through intermediate states and the other way around in the declining phase). Most importantly, these {α }{SK} values in the low angular momentum advective component are fully self-consistent in the sense that they remain below the critical value {α }{cr} required to form a Keplerian disk. For a further consistency check, we compute the {α }{{K}} of the Keplerian component, and find that in each of the objects, {α }{SK} < {α }{cr} < {α }{{K}}.

  3. Disc-jet Coupling in the 2009 Outburst of the Black Hole Candidate H1743-322

    Science.gov (United States)

    Miller-Jones, J. C. A.; Sivakoff, G. R.; Altamirano, D.; Coriat, M.; Corbel, S.; Dhawan, V.; Krimm, H. A.; Remillard, R. A.; Rupen, M. P.; Russell, D. M.; hide

    2012-01-01

    We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743-322. With the high angular resolution of the Very Long Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743-322, the ejection was contemporaneous with a quenching of the radio emission, prior to the start of the major radio flare. This contradicts previous assumptions that the onset of the radio flare marks the moment of ejection. The jet speed appears to vary between outbursts with a positive correlation outburst luminosity. The compact core radio jet reactivated on transition to the hard intermediate state at the end of the outburst and not when the source reached the low hard spectral state. Comparison with the known near-infrared behaviour of the compact jets suggests a gradual evolution of the compact jet power over a few days near beginning the and end of an outburst

  4. The XMM-Newton spectrum of a candidate recoiling supermassive black hole: An elusive inverted P-Cygni profile

    Energy Technology Data Exchange (ETDEWEB)

    Lanzuisi, G.; Civano, F.; Marchesi, S.; Hickox, R. [Department of Physics and Astronomy, Dartmouth College, Wilder Laboratory, Hanover, NH 03855 (United States); Comastri, A.; Cappelluti, N. [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Costantini, E. [SRON, Netherlands Institute for Space Research, Sorbonnelaan, 2, 3584 CA Utrecht (Netherlands); Elvis, M.; Fruscione, A. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Mainieri, V. [European Southern Observatory, Karl-Schwarschild-Strasse 2, D-85748 Garching bei Munchen (Germany); Jahnke, K. [Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg (Germany); Komossa, S. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Vignali, C.; Brusa, M. [Dipartimento di Astronomia, Universitá degli Studi di Bologna, via Ranzani 1, I-40127 Bologna (Italy)

    2013-11-20

    We present a detailed spectral analysis of new XMM-Newton data of the source CXOC J100043.1+020637, also known as CID-42, detected in the COSMOS survey at z = 0.359. Previous works suggested that CID-42 is a candidate recoiling supermassive black hole (SMBH) showing also an inverted P-Cygni profile in the X-ray spectra at ∼6 keV (rest) with an iron emission line plus a redshifted absorption line (detected at 3σ in previous XMM-Newton and Chandra observations). Detailed analysis of the absorption line suggested the presence of ionized material flowing into the black hole at high velocity. In the new long XMM-Newton observation, while the overall spectral shape remains constant, the continuum 2-10 keV flux decrease of ∼20% with respect to previous observation and the absorption line is undetected. The upper limit on the intensity of the absorption line is EW < 162 eV. Extensive Monte Carlo simulations show that the nondetection of the line is solely due to variation in the properties of the inflowing material, in agreement with the transient nature of these features, and that the intensity of the line is lower than the previously measured with a probability of 98.8%. In the scenario of CID-42 as a recoiling SMBH, the absorption line can be interpreted as being due to an inflow of gas with variable density that is located in the proximity of the SMBH and recoiling with it. New monitoring observations will be requested to further characterize this line.

  5. High-energy observations of the state transition of the X-ray nova and black hole candidate XTE J1720-318

    DEFF Research Database (Denmark)

    Bel, M.C.; Rodriguez, J.; Sizun, P.

    2004-01-01

    We report the results of extensive high-energy observations of the X-ray transient and black hole candidate XTE J1720-318 performed with INTEGRAL, XMM-Newton and RXTE. The source, which underwent an X-ray outburst in 2003 January, was observed in February in a spectral state dominated by a soft......, typical of a black-hole binary in the so-called High/Soft State. We then followed the evolution of the source outburst over several months using the INTEGRAL Galactic Centre survey observations. The source became active again at the end of March: it showed a clear transition towards a much harder state...... of the black hole X-ray novae class which populate our galactic bulge and we discuss its properties in the frame of the spectral models used for transient black hole binaries....

  6. Buried Black Hole Growth in Advanced Mergers: The Discovery of a Large Population of Dual AGN Candidates by Chandra

    Science.gov (United States)

    Satyapal, Shobita; Secrest, Nathan; Ellison, Sara L.; Ricci, Claudio; Pfeifle, Ryan William; Blecha, Laura; Rothberg, Barry; Gliozzi, Mario; Constantin, Anca; Ferguson, Jason

    2018-01-01

    Interactions between galaxies are predicted to cause gas inflows that can potentially trigger nuclear activity. Since the inflowing material can obscure the central regions of interacting galaxies, a potential limitation of previous optical studies is that obscured active galactic nuclei (AGNs) can be missed at various stages along the merger sequence. In a recent large mid-infrared study of AGNs in mergers, we demonstrated that the fraction of obscured AGNs increases with merger stage, with the most energetically dominant optically obscured AGNs becoming more prevalent in the most advanced mergers, consistent with theoretical predictions. In a recent Chandra program, we discovered 8 out of 15 infrared-selected advanced mergers that display two nuclear X-ray sources with separations of a few kiloparsecs consistent with highly absorbed dual AGNs, demonstrating that WISE pre-selection may be effective in identifying a new population of optically invisible dual AGNs. These observations reveal that infrared and X-ray observations are critical in uncovering the most efficient environments for supermassive black hole accretion and a key stage in galaxy evolution. In this talk, I will discuss Chandra, NuSTAR, and near-infrared spectroscopic observations of these dual AGN candidates and recent hydrodynamic simulations that predict that this key stage in galaxy evolution is expected to be highly obscured.

  7. DISCOVERY OF HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS IN THE BLACK HOLE CANDIDATE IGR J17091-3624

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano, D. [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH Amsterdam (Netherlands); Belloni, T., E-mail: d.altamirano@uva.nl [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy)

    2012-03-15

    We report the discovery of 8.5{sigma} high-frequency quasi-periodic oscillations (HFQPOs) at 66 Hz in the Rossi X-ray Timing Explorer data of the black hole candidate IGR J17091-3624, a system whose X-ray properties are very similar to those of microquasar GRS 1915+105. The centroid frequency of the strongest peak is {approx}66 Hz, its quality factor above five, and its rms is between 4% and 10%. We found a possible additional peak at 164 Hz when selecting a subset of the data; however, at the 4.5{sigma} level we consider this detection marginal. These QPOs have hard spectrum and are stronger in observations performed between 2011 September and October, during which IGR J17091-3624 displayed for the first time light curves that resemble those of the {gamma} variability class in GRS 1915+105. We find that the 66 Hz QPO is also present in previous observations (4.5{sigma}), but only when averaging {approx}235 ks of relatively high count rate data. The fact that the HFQPOs frequency in IGR J17091-3624 matches surprisingly well with that seen in GRS 1915+105 raises questions on the mass scaling of QPOs frequency in these two systems. We discuss some possible interpretations; however, they all strongly depend on the distance and mass of IGR J17091-3624, both completely unconstrained today.

  8. Beginning Swift programming

    CERN Document Server

    Lee, Wei-Meng

    2014-01-01

    Enter the Swift future of iOS and OS X programming Beginning Swift Programming is your ideal starting point for creating Mac, iPhone, and iPad apps using Apple's new Swift programming language. Written by an experienced Apple developer and trainer, this comprehensive guide explains everything you need to know to jumpstart the creation of your app idea. Coverage includes data types, strings and characters, operators and functions, arrays and dictionaries, control flow, and looping, with expert guidance on classes, objects, class inheritance, closures, protocols, and generics. This succinct - ye

  9. Recent Progress on GRBs with Swift

    Science.gov (United States)

    Gehrels, Neil

    2012-01-01

    Gamma-ray bursts (GRBs) are powerful explosions, visible to high red shift, and thought to be the signature of black hole formation. The Swift Observatory has been detecting 100 bursts per year for 7 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from 1 minute after the burst, continuing for days. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type. II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are providing a new tool to study the high redshift universe. Swift has detected several events at z>S and one at z=9.4 giving metallicity measurements and other data on galaxies at previously inaccessible distances. The talk will present the latest results from Swift in GRB astronomy .

  10. The twisted radio structure of PSO J334.2028+01.4075, still a supermassive binary black hole candidate

    Science.gov (United States)

    Mooley, K. P.; Wrobel, J. M.; Anderson, M. M.; Hallinan, G.

    2018-01-01

    Supermassive binary black holes (BBHs) on sub-parsec scales are prime targets for gravitational wave experiments. They also provide insights on close binary evolution and hierarchical structure formation. Sub-parsec BBHs cannot be spatially resolved but indirect methods can identify candidates. In 2015 Liu et al. reported an optical-continuum periodicity in the quasar PSO J334.2028+01.4075, with the estimated mass and rest-frame period suggesting an orbital separation of about 0.006 pc (0.7 μ arcsec). The persistence of the quasar's optical periodicity has recently been disfavoured over an extended baseline. However, if a radio jet is launched from a sub-parsec BBH, the binary's properties can influence the radio structure on larger scales. Here, we use the Very Long Baseline Array (VLBA) and Karl G. Jansky Very Large Array (VLA) to study the parsec- and kiloparsec-scale emission energized by the quasar's putative BBH. We find two VLBA components separated by 3.6 mas (30 pc), tentatively identifying one as the VLBA 'core' from which the other was ejected. The VLBA components contribute to a point-like, time-variable VLA source that is straddled by lobes spanning 8 arcsec (66 kpc). We classify PSO J334.2028+01.4075 as a lobe-dominated quasar, albeit with an atypically large twist of 39° between its elongation position angles on parsec- and kiloparsec-scales. By analogy with 3C 207, a well-studied lobe-dominated quasar with a similarly-rare twist, we speculate that PSO J334.2028+01.4075 could be ejecting jet components over an inner cone that traces a precessing jet in a BBH system.

  11. Game development with Swift

    CERN Document Server

    Haney, Stephen

    2015-01-01

    If you wish to create and publish fun iOS games using Swift, then this book is for you. You should be familiar with basic programming concepts. However, no prior game development or Apple ecosystem experience is required.

  12. The Swift Turbidity Marker

    Science.gov (United States)

    Omar, Ahmad Fairuz; MatJafri, Mohd Zubir

    2011-01-01

    The Swift Turbidity Marker is an optical instrument developed to measure the level of water turbidity. The components and configuration selected for the system are based on common turbidity meter design concepts but use a simplified methodology to produce rapid turbidity measurements. This work is aimed at high school physics students and is the…

  13. Reflection Spectra of the Black Hole Binary Candidate MAXI J1535-571 in the Hard State Observed by NuSTAR

    Science.gov (United States)

    Xu, Yanjun; Harrison, Fiona A.; García, Javier A.; Fabian, Andrew C.; Fürst, Felix; Gandhi, Poshak; Grefenstette, Brian W.; Madsen, Kristin K.; Miller, Jon M.; Parker, Michael L.; Tomsick, John A.; Walton, Dominic J.

    2018-01-01

    We report on a Nuclear Spectroscopic Telescope Array (NuSTAR) observation of the recently discovered bright black hole candidate MAXI J1535-571. NuSTAR observed the source on MJD 58003 (five days after the outburst was reported). The spectrum is characteristic of a black hole binary in the hard state. We observe clear disk reflection features, including a broad Fe Kα line and a Compton hump peaking around 30 keV. Detailed spectral modeling reveals a narrow Fe Kα line complex centered around 6.5 keV on top of the strong relativistically broadened Fe Kα line. The narrow component is consistent with distant reflection from moderately ionized material. The spectral continuum is well described by a combination of cool thermal disk photons and a Comptonized plasma with the electron temperature {{kT}}{{e}}=19.7+/- 0.4 keV. An adequate fit can be achieved for the disk reflection features with a self-consistent relativistic reflection model that assumes a lamp-post geometry for the coronal illuminating source. The spectral fitting measures a black hole spin a> 0.84, inner disk radius {R}{in}confidence), indicating no significant disk truncation and a compact corona. Although the distance and mass of this source are not currently known, this suggests the source was likely in the brighter phases of the hard state during this NuSTAR observation.

  14. INTEGRAL detects Swift J1910.2-0546 (= MAXI J1910-057) in the hard X-rays

    DEFF Research Database (Denmark)

    Bodaghee, A.; Bozzo, E.; Tomsick, J. A.

    2012-01-01

    The black hole candidate Swift J1910.2-0546 (= MAXI J1910-057), which was reported to be transitioning to the hard state (ATels #4273, #4295), was in the field of view of INTEGRAL's hard X-ray imager ISGRI during observations of the Scutum/Sagittarius region performed from 2012 August 20 at 23......:28:03 to August 21 at 03:09:59 UTC (INTEGRAL revolution 1203). A mosaic image combining 12.6 ks of data reveals that Swift J1910.2-0546 is detected by ISGRI at a significance level of 13.7 sigma in the 18--40 keV energy band and at 9.4 sigma in the 40--100 keV energy band. Source count rates in these bands are 15...... curves and images of this source (and others in the field) can be found at the ISA project home page: http://sprg.ssl.berkeley.edu/~bodaghee/isa We thank the ISDC shift team for alerting us to the presence of Swift J1910.2-0546 in our observations and for their help in analyzing the data....

  15. X-Ray Timing and Spectral Observations of Galactic Black Hole Candidate XTE J1550--564 During Outburst

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, Kaice T

    2002-12-11

    Soft X-ray transients (SXTs), a sub-class of low-mass X-ray binaries (LMXBs), provide a unique opportunity to test General Relativity and to probe fundamental physics under conditions terrestrially unattainable. SXT outbursts are of great interest because they allow the study of LMXBs under a wide range of accretion rates. The majority of known SXTs contain black holes, therefore SXT outbursts are key to understanding accretion physics around black holes and in active galactic nuclei, which are thought to contain supermassive, M {approx} 10{sup 6} - 10{sup 10} M{circle_dot}, where M{circle_dot} is one solar mass, central compact objects. These compact objects are most likely black holes, which exhibit, on a much larger scale, accretion physics similar to that around black holes in SXTs. In this work, the timing and spectral properties of the SXT and microquasar XTE J1550-564 during outburst are studied. Observations made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS) are emphasized. USA data show a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing USA flux and a fractional rms amplitude which is correlated with the USA hardness ratio (4-16 keV/1-4 keV). Several high-frequency quasi-periodic oscillations (HFQPOs) were detected by the Rossi X-ray Timing Explorer (RXTE), during periods where the LFQPO is seen to be weakening or not detectable at all. The evolution of the USA hardness ratio with time and source flux is examined. The hardness-intensity diagram shows counterclockwise cyclical evolution and possibly indicates the presence of two independent accretion flows: a geometrically thin, optically thick accretion disk and a hot sub-Keplerian flow.

  16. FIRST LONG-TERM OPTICAL SPECTRAL MONITORING OF A BINARY BLACK HOLE CANDIDATE E1821+643. I. VARIABILITY OF SPECTRAL LINES AND CONTINUUM

    Energy Technology Data Exchange (ETDEWEB)

    Shapovalova, A. I.; Burenkov, A. N.; Zhdanova, V. E. [Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz, Karachaevo-Cherkesia 369167 (Russian Federation); Popović, L. Č. [Astronomical Observatory, Volgina 7, 11160 Belgrade 74 (Serbia); Chavushyan, V. H.; Valdés, J. R.; Patiño-Álvarez, V.; León-Tavares, J.; Torrealba, J. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, Puebla, México (Mexico); Ilić, D.; Kovačević, A. [Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade (Serbia); Kollatschny, W., E-mail: ashap@sao.ru [Institut für Astrophysik, Georg-August-Universität Göttingen (Germany)

    2016-02-15

    We report the results of the first long-term (1990–2014) optical spectrophotometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift, high-luminosity, radio-quiet quasar. In the monitored period, the continua and Hγ fluxes changed about two times, while the Hβ flux changed about 1.4 times. We found periodical variations in the photometric flux with periods of 1200, 1850, and 4000 days, and 4500-day periodicity in the spectroscopic variations. However, the periodicity of 4000–4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, buts with small significance level, while the 1850-day period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s{sup −1}. However, Hβ shows a broader mean profile and has a larger time lag (τ ∼ 120 days) than Hγ (τ ∼ 60 days). We estimate that the mass of the black hole is ∼2.6 × 10{sup 9} M{sub ⊙}. The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of the broad lines, we discuss a scenario where dense, gas-rich, cloudy-like structures are orbiting around a recoiling black hole.

  17. A Thermote, a Novel Thermal Element Simplifying the Finding of a Medium's Entropy Emerges as a Sensible Dark Matter Candidate from Primordial Black Holes with a Mass in Range of Axion's, a Leading Candidate

    Science.gov (United States)

    Feria, Erlan H.

    2017-06-01

    Black holes acting as dark matter have been predicted, e.g., via a duality theory in (Feria 2011, Proc. IEEE Int’l Conf. on SMC, Alaska, USA) and via observations in (Kashlinsky 2016, AJL). Here a thermote, a novel thermal element simplifying the finding of a medium’s entropy, emerges as a dark matter candidate from primordial black holes with a mass in range of axion's, a leading candidate. The thermote energy, eT, is defined as the average thermal energy contributed to a particle’s motion by the medium’s degrees of freedom (DoF) and is thus given by eT=NDoFkBT/2 where NDoF is the DoF number (e.g., NDoF=2 for a black-hole since only in its event-horizon particle motions can occur) and kBT/2 is the thermal energy contributed by each degree of freedom (kB is the Boltzmann constant and T is temperature). The entropy S of a spherical homogeneous medium is then simply stated as S=(kB/2)E/eT where E=Mc2 is the medium's rest-energy, with M its point-mass and c the speed of light, and eT=NDoFkBT/2 is the thermote's kinetic-energy. This simple equation naturally surfaced from a rest/kinetic or retention/motion mass-energy duality theory where, e.g., black-holes and vacuums form together such a duality with black holes offering the least resistance to mass-energy rest, or retention, and vacuums offering the least resistance to mass-energy kinetics, or motions. In turn, this duality theory has roots in the universal cybernetics duality principle (UCDP) stating “synergistic physical and mathematical dualities arise in efficient system designs” (Feria 2014, http://dx.doi.org/10.1117/2.1201407.005429, SPIE Newsroom). Our thermote based entropy finding method is applicable to spherical homogeneous mediums such as black-holes, photon-gases, and flexible-phase (Feria 2016, Proc. IEEE Int’l Conf. on Smart Cloud, Columbia University, NY, USA), where the thermote of a primordial black hole, with NDoF=2 and a CMB radiation temperature of T=2.725 kelvin, emerges as a

  18. The (w)hole survey: An unbiased sample study of transition disk candidates based on Spitzer catalogs

    Science.gov (United States)

    van der Marel, N.; Verhaar, B. W.; van Terwisga, S.; Merín, B.; Herczeg, G.; Ligterink, N. F. W.; van Dishoeck, E. F.

    2016-08-01

    Understanding disk evolution and dissipation is essential for studies of planet formation. Transition disks, I.e., disks with large dust cavities and gaps, are promising candidates of active evolution. About two dozen candidates, selected by their spectral energy distribution (SED), have been confirmed to have dust cavities through millimeter interferometric imaging, but this sample is biased toward the brightest disks. The Spitzer surveys of nearby low-mass star-forming regions have resulted in more than 4000 young stellar objects. Using color criteria, we selected a sample of ~150 candidates and an additional 40 candidates and known transition disks from the literature. The Spitzer data were complemented by new observations at longer wavelengths, including new JCMT and APEX submillimeter photometry, and WISE and Herschel-PACS mid- and far-infrared photometry. Furthermore, optical spectroscopy was obtained and stellar types were derived for 85% of the sample, including information from the literature. The SEDs were fit to a grid of RADMC-3D disk models with a limited number of parameters: disk mass, inner disk mass, scale height and flaring, and disk cavity radius, where the latter is the main parameter of interest. About 72% of our targets possibly have dust cavities based on the SED. The derived cavity sizes are consistent with imaging/modeling results in the literature, where available. Trends are found with Ldisk over L∗ ratio and stellar mass and a possible connection with exoplanet orbital radii. A comparison with a previous study where color observables are used reveals large overlap between their category of planet-forming disks and our transition disks with cavities. A large number of the new transition disk candidates are suitable for follow-up observations with ALMA. Full Tables 4, 5, A.1-A.3, C.1, and D.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  19. Hard state of SWIFT J1753.5-0127 during 2005 outburst

    Science.gov (United States)

    Jana, Arghajit; Debnath, Dipak; Chakrabarti, Sandip Kumar; Mondal, Santanu; Chatterjee, Debjit; Molla, Aslam Ali

    2016-07-01

    Low mass X-ray binary (LMXRB) Galactic black hole candidate (BHC) Swift J1753.5-0127 was discovered on June, 2005 by Swift/BAT. We analyzed 2.5-25 keV RXTE/PCA data of the BHC during its 2005 outburst with two component advective flow (TCAF) model generated fits file as an additive local table model in XSPEC. From the spectral analysis with TCAF, we extracted physical parameters such as Keplerian disk rate, sub-Keplerian halo rate, shock location and shock strength during entire phase of the 2005 outburst. We also find the most probable range of the mass of the BHC is in the range of 4-7 M_{Sun}. During the entire outburst, we find quasi periodic oscillations (QPOs) almost on a daily basis. From the variations of accretion rate ratio (ARR=halo rate/disk rate), QPO frequencies and photon indices, we conclude that the source is in hard state during the entire outburst. This may be because of the low accretion rate in the Keplerian component, which is indeed insufficient to cool down hot Comptonized region i.e., so-called CENBOL according to TCAF. Soft, soft-intermediate and hard-intermediate states are absent in the present outburst.

  20. Radio afterglow of the jetted tidal disruption event Swift J1644+57

    Directory of Open Access Journals (Sweden)

    Mimica P.

    2012-12-01

    Full Text Available The recent transient event Swift J1644+57 has been interpreted as resulting from a relativistic outflow, powered by the accretion of a tidally disrupted star onto a supermassive black hole. This discovery of a new class of relativistic transients opens new windows into the study of tidal disruption events (TDEs and offers a unique probe of the physics of relativistic jet formation and the conditions in the centers of distant quiescent galaxies. Unlike the rapidly-varying γ/X-ray emission from Swift J1644+57, the radio emission varies more slowly and is well modeled as synchrotron radiation from the shock interaction between the jet and the gaseous circumnuclear medium (CNM. Early after the onset of the jet, a reverse shock propagates through and decelerates the ejecta released during the first few days of activity, while at much later times the outflow approaches the self-similar evolution of Blandford and McKee. The point at which the reverse shock entirely crosses the earliest ejecta is clearly observed as an achromatic break in the radio light curve at t ≈ 10 days. The flux and break frequencies of the afterglow constrain the properties of the jet and the CNM, including providing robust evidence for a narrowly collimated jet. I briefly discuss the implications of Swift J1644+57 for the fraction of TDEs accompanied by relativistic jets; the physics of jet formation more broadly; and the prospects for detecting off-axis TDE radio emission, either via follow-up observations of TDE candidates discovered at other wavelengths or blindly with upcoming wide-field radio surveys. The radio rebrightening observed months after the onset of the jet remains a major unsolved mystery, the resolution of which may require considering a jet with more complex (temporal or angular structure.

  1. A strong and broad iron line in the XMM-Newton spectrum of the new X-ray transient and black-hole candidate XTE J1652-453

    NARCIS (Netherlands)

    Hiemstra, Beike; Mendez, Mariano; Done, Chris; Trigo, Maria Diaz; Altamirano, Diego; Casella, Piergiorgio

    2010-01-01

    ABSTRACT We observed the new X-ray transient and black-hole candidate XTE J1652−453 si- multaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTE J1652−453 was in the hard-intermediate state. The spectrum shows a

  2. Hard X-ray detection of the black hole candidates 4U 1630-47 and IGR J17091-3624 up to 200 keV with INTEGRAL

    DEFF Research Database (Denmark)

    Bodaghee, A.; Kuulkers, E.; Tomsick, J. A.

    2012-01-01

    During monitoring observations of the Norma and Inner Perseus Arms (rev. 1209: 2012 Sept. 6 from 18:18:23 to 22:00:21 UTC), INTEGRAL-ISGRI revealed that the accreting black hole candidates 4U 1630-47 and IGR J17091-3624 have brightened in the hard X-rays. Mosaic images consisting of 12.6 ks worth...

  3. Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance

    Science.gov (United States)

    Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

    2010-01-01

    We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

  4. A search for periodicity in the x ray spectrum of black hole candidate A0620-00

    Science.gov (United States)

    Clark, George W.; Plaks, Kenneth

    1991-01-01

    The archived data from the SAS-3 observations of the X-ray nova A0620-00, the best of the stellar blackhole candidates, were exhaustively examined for evidence of variable phenomena correlated with the orbital motion of the binary system of which it is a member. The original analysis of these data was completed before discovery of the binary companion and determination of the orbital period of the system. New interest was drawn to the task of a reexamination of the archive data by the recent discovery of the massive nature of the X-ray source through analysis of the Doppler variations and ellipsoidal light variations of the faint K-star companion by McClintock and Remillard. The archive research, carried out under the supervision of the principal investigator, was the topic of the thesis submitted to the MIT Department of Physics by Kenneth Plaks in partial fulfillment of the requirements for the degree of Master of Science. Plaks' effort was focused on the elimination of fluctuations in the data due to errors in attitude solutions and other extraneous causes. The first products of his work were long-term light curves of the X-ray intensities in the various energy channels as functions of time during the time from outbursts in August 1975 to quiescence approximately 6 months later. These curves, are refined versions of the preliminary results published in 1976 (Matilsky et al. 1976). Smooth exponentials were fitted to these long term light curves to provide the basis for detrending the data, thereby permitting a calculation of residuals derived by subtracting the fitted curve from the data. The residuals were then analyzed by Fourier analysis to search for variations with the period of the binary orbit, namely 7.75 hours. No evidence of an orbital periodicity was found. However, the refined light curve provides a much clearer picture of the outburst and subsequent decay of the X-ray luminosity. In fact, there were two outbursts, each followed by an exponential

  5. A search for periodicity in the X ray spectrum of black hole candidate A0620-00

    Science.gov (United States)

    Clark, George W.; Plaks, Kenneth

    The archived data from the SAS-3 observations of the X-ray nova A0620-00, the best of the stellar blackhole candidates, were exhaustively examined for evidence of variable phenomena correlated with the orbital motion of the binary system of which it is a member. The original analysis of these data was completed before discovery of the binary companion and determination of the orbital period of the system. New interest was drawn to the task of a reexamination of the archive data by the recent discovery of the massive nature of the X-ray source through analysis of the Doppler variations and ellipsoidal light variations of the faint K-star companion by McClintock and Remillard. The archive research, carried out under the supervision of the principal investigator, was the topic of the thesis submitted to the MIT Department of Physics by Kenneth Plaks in partial fulfillment of the requirements for the degree of Master of Science. Plaks' effort was focused on the elimination of fluctuations in the data due to errors in attitude solutions and other extraneous causes. The first products of his work were long-term light curves of the X-ray intensities in the various energy channels as functions of time during the time from outbursts in August 1975 to quiescence approximately 6 months later. These curves, are refined versions of the preliminary results published in 1976 (Matilsky et al. 1976). Smooth exponentials were fitted to these long term light curves to provide the basis for detrending the data, thereby permitting a calculation of residuals derived by subtracting the fitted curve from the data. The residuals were then analyzed by Fourier analysis to search for variations with the period of the binary orbit, namely 7.75 hours. No evidence of an orbital periodicity was found. However, the refined light curve provides a much clearer picture of the outburst and subsequent decay of the X-ray luminosity. In fact, there were two outbursts, each followed by an exponential

  6. Demonstrating the Likely Neutron Star Nature of Five M31 Globular Cluster Sources with Swift-NuSTAR Spectroscopy

    Science.gov (United States)

    Maccarone, Thomas J.; Yukita, Mihoko; Hornschemeier, Ann; Lehmer, Bret D.; Antoniou, Vallia; Ptak, Andrew; Wik, Daniel R.; Zezas, Andreas; Boyd, Padi; Kennea, Jamie; hide

    2016-01-01

    We present the results of a joint Swift-NuSTAR spectroscopy campaign on M31. We focus on the five brightest globular cluster X-ray sources in our fields. Two of these had previously been argued to be black hole candidates on the basis of apparent hard-state spectra at luminosities above those for which neutron stars are in hard states. We show that these two sources are likely to be Z-sources (i.e. low magnetic field neutron stars accreting near their Eddington limits), or perhaps bright atoll sources (low magnetic field neutron stars which are just a bit fainter than this level) on the basis of simultaneous Swift and NuSTAR spectra which cover a broader range of energies. These new observations reveal spectral curvature above 6-8 keV that would be hard to detect without the broader energy coverage the NuSTAR data provide relative to Chandra and XMM-Newton. We show that the other three sources are also likely to be bright neutron star X-ray binaries, rather than black hole X-ray binaries. We discuss why it should already have been realized that it was unlikely that these objects were black holes on the basis of their being persistent sources, and we re-examine past work which suggested that tidal capture products would be persistently bright X-ray emitters. We discuss how this problem is likely due to neglecting disc winds in older work that predict which systems will be persistent and which will be transient.

  7. Demonstrating the likely neutron star nature of five M31 globular cluster sources with Swift-NuSTAR spectroscopy

    DEFF Research Database (Denmark)

    Maccarone, Thomas J.; Yukita, Mihoko; Hornschemeier, Ann

    2016-01-01

    for which neutron stars are in hard states. We show that these two sources are likely to be Z-sources (i.e. low magnetic field neutron stars accreting near their Eddington limits), or perhaps bright atoll sources (low magnetic field neutron stars which are just a bit fainter than this level) on the basis...... are also likely to be bright neutron star X-ray binaries, rather than black hole X-ray binaries. We discuss why it should already have been realized that it was unlikely that these objects were black holes on the basis of their being persistent sources, and we re-examine past work which suggested......We present the results of a joint Swift-NuSTAR spectroscopy campaign on M31. We focus on the five brightest globular cluster X-ray sources in our fields. Two of these had previously been argued to be black hole candidates on the basis of apparent hard-state spectra at luminosities above those...

  8. SWiFT Software Quality Assurance Plan.

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    This document describes the software development practice areas and processes which contribute to the ability of SWiFT software developers to provide quality software. These processes are designed to satisfy the requirements set forth by the Sandia Software Quality Assurance Program (SSQAP). APPROVALS SWiFT Software Quality Assurance Plan (SAND2016-0765) approved by: Department Manager SWiFT Site Lead Dave Minster (6121) Date Jonathan White (6121) Date SWiFT Controls Engineer Jonathan Berg (6121) Date CHANGE HISTORY Issue Date Originator(s) Description A 2016/01/27 Jon Berg (06121) Initial release of the SWiFT Software Quality Assurance Plan

  9. Gamma Ray Bursts in the Swift-Fermi Era

    Science.gov (United States)

    Gehrels, Neil; Razzaque, Soebur

    2013-01-01

    Gamma-ray bursts (GRBs) are among the most violent occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole birth. They are highly luminous events and provide excellent probes of the distant universe. GRB research has greatly advanced over the past 10 years with the results from Swift, Fermi and an active follow-up community. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  10. VizieR Online Data Catalog: Short GRBs with Fermi GBM and Swift BAT (Burns+, 2016)

    Science.gov (United States)

    Burns, E.; Connaughton, V.; Zhang, B.-B.; Lien, A.; Briggs, M. S.; Goldstein, A.; Pelassa, V.; Troja, E.

    2018-01-01

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. (4 data files).

  11. ATCA radio detection of MAXI J1535-571 indicates it is a strong black hole X-ray binary candidate

    Science.gov (United States)

    Russell, T. D.; Miller-Jones, J. C. A.; Sivakoff, G. R.; Tetarenko, A. J.; Jacpot Xrb Collaboration

    2017-09-01

    MAXI J1535-571 is a newly discovered Galactic hard X-ray transient (GCN #21788, ATels #10699, 10700). Following its identification as a potential hard-state low-mass X-ray binary (ATel #10702) and a potential black hole system (ATel #10708), we conducted target of opportunity observations of this source with the Australia Telescope Compact Array (ATCA).

  12. Food of the Little Swift Apus affinis and African Black Swift Apus ...

    African Journals Online (AJOL)

    The food habits of the Little Swift Apus affinis and African Black Swift Apus barbatus were quantified at Kimberley, Northern Cape province and Makapansgat, Limpopo province, South Africa. As previously documented for other species, both of these swifts took a wide variety of aerial arthropods including spiders as well as ...

  13. Swift GRBs and the blast wave model

    NARCIS (Netherlands)

    Curran, P.A.; van der Horst, A.J.; Starling, R.L.C.; Wijers, R.A.M.J.

    2009-01-01

    The complex structure of the light curves of Swift GRBs has made their interpretation and that of the blast wave caused by the burst, more difficult than in the pre-Swift era. We aim to constrain the blast wave parameters: electron energy distribution, p, density profile of the circumburst medium,

  14. The first ten years of Swift supernovae

    Science.gov (United States)

    Brown, Peter J.; Roming, Peter W. A.; Milne, Peter A.

    2015-09-01

    The Swift Gamma Ray Burst Explorer has proven to be an incredible platform for studying the multiwavelength properties of supernova explosions. In its first ten years, Swift has observed over three hundred supernovae. The ultraviolet observations reveal a complex diversity of behavior across supernova types and classes. Even amongst the standard candle type Ia supernovae, ultraviolet observations reveal distinct groups. When the UVOT data is combined with higher redshift optical data, the relative populations of these groups appear to change with redshift. Among core-collapse supernovae, Swift discovered the shock breakout of two supernovae and the Swift data show a diversity in the cooling phase of the shock breakout of supernovae discovered from the ground and promptly followed up with Swift. Swift observations have resulted in an incredible dataset of UV and X-ray data for comparison with high-redshift supernova observations and theoretical models. Swift's supernova program has the potential to dramatically improve our understanding of stellar life and death as well as the history of our universe.

  15. NuSTAR and Swift Observations of Swift J1357.2–0933 During an Early Phase of Its 2017 Outburst

    Science.gov (United States)

    Stiele, H.; Kong, A. K. H.

    2018-01-01

    We present a detailed spectral analysis of Swift and NuSTAR observations of the very faint X-ray transient and black hole system, Swift J1357.2–0933, during an early, low-hard state of its 2017 outburst. Swift J1357.2–0933 was observed at ∼0.02% of the Eddington luminosity (for a distance of 2.3 kpc and a mass of 4 {\\text{}}{M}ȯ ). Despite the low luminosity, the broadband X-ray spectrum between 0.3 and 78 keV requires the presence of a disk blackbody component with an inner disk temperature of {T}{in}∼ 0.06 {keV} in addition to a thermal Comptonization component with a photon index of {{Γ }}∼ 1.70. Using a more physical model, which takes strong relativistic effects into account, and assuming a high inclination of 70°, which is motivated by the presence of dips in optical light curves, we find that the accretion disk is truncated within a few {R}{ISCO} from the black hole, independent of the spin.

  16. Swift: Compiled Inference for Probabilistic Programming Languages

    OpenAIRE

    Wu, Yi; Li, Lei; Russell, Stuart; Bodik, Rastislav

    2016-01-01

    A probabilistic program defines a probability measure over its semantic structures. One common goal of probabilistic programming languages (PPLs) is to compute posterior probabilities for arbitrary models and queries, given observed evidence, using a generic inference engine. Most PPL inference engines---even the compiled ones---incur significant runtime interpretation overhead, especially for contingent and open-universe models. This paper describes Swift, a compiler for the BLOG PPL. Swift-...

  17. Phase imaging in brain using SWIFT

    Science.gov (United States)

    Lehto, Lauri Juhani; Garwood, Michael; Gröhn, Olli; Corum, Curtis Andrew

    2015-03-01

    The majority of MRI phase imaging is based on gradient recalled echo (GRE) sequences. This work studies phase contrast behavior due to small off-resonance frequency offsets in brain using SWIFT, a FID-based sequence with nearly zero acquisition delay. 1D simulations and a phantom study were conducted to describe the behavior of phase accumulation in SWIFT. Imaging experiments of known brain phase contrast properties were conducted in a perfused rat brain comparing GRE and SWIFT. Additionally, a human brain sample was imaged. It is demonstrated how SWIFT phase is orientation dependent and correlates well with GRE, linking SWIFT phase to similar off-resonance sources as GRE. The acquisition time is shown to be analogous to TE for phase accumulation time. Using experiments with and without a magnetization transfer preparation, the likely effect of myelin water pool contribution is seen as a phase increase for all acquisition times. Due to the phase accumulation during acquisition, SWIFT phase contrast can be sensitized to small frequency differences between white and gray matter using low acquisition bandwidths.

  18. Are Spectral and Timing Correlations Similar in Different Spectral States in Black Hole X-Ray Binaries?

    NARCIS (Netherlands)

    Kalamkar, M.; Reynolds, M.T.; van der Klis, M.; Altamirano, D.; Miller, J.M.

    2015-01-01

    We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5-0127, and GX 339-4 with the Swift X-ray Telescope (XRT). The bandpass of the XRT has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a

  19. Swift-Hohenberg-type model

    Science.gov (United States)

    Oza, Anand; Dunkel, Joern

    Recent experiments from the Zvonimir Dogic Lab (Brandeis University) demonstrated that ATP-driven microtubule-kinesin bundles can self-assemble into two-dimensional active liquid crystals that exhibit a rich creation and annihilation dynamics of topological defects, reminiscent of particle-pair production processes in quantum systems. This remarkable discovery has sparked considerable theoretical and experimental interest. Here, we present and validate a minimal continuum theory for this new class of active matter systems by modifying the classical Landau-de Gennes theory for liquid crystals, obtaining a tensorial Swift-Hohenberg-type PDE. We simulate the resulting model numerically and develop an algorithm for tracking topological defects. We find that the resulting model agrees quantitatively with recently published data and predicts a regime of antipolar defect ordering. Ordered states go unstable as the activity parameter is increased, yet the chaotic defect dynamics still exhibit local antipolar ordering. Generally, our results suggest that complex nonequilibrium pattern-formation phenomena might be predictable from a few fundamental symmetry-breaking and scale-selection principles.

  20. Tandem Swift and INTEGRAL Data to Revisit the Orbital and Superorbital Periods of 1E 1740.7-2942

    Science.gov (United States)

    Stecchini, Paulo Eduardo; Castro, Manuel; Jablonski, Francisco; D'Amico, Flavio; Braga, João

    2017-07-01

    The black hole candidate 1E 1740.7-2942 is one of the strongest hard X-ray sources in the Galactic Center region. No counterparts in longer wavelengths have been identified for this object yet. The presence of characteristic timing signatures in the flux history of X-ray sources has been shown to be an important diagnostic tool for the properties of these systems. Using simultaneous data from NASA’s Swift and ESA’s INTEGRAL missions, we have found two periodic signatures at 12.61 ± 0.06 days and 171.1 ± 3.0 days in long-term hard X-ray light curves of 1E 1740.7-2942. We interpret those as the orbital and superorbital periods of the object, respectively. The reported orbital period is in good agreement with previous studies of 1E 1740.7-2942 using NASA’s RXTE data. We present here the first firm evidence of a superorbital period for 1E 1740.7-2942, which has important implications for the nature of the binary system.

  1. Swift J0243.6+6124: Swift discovery of an accreting NS transient

    Science.gov (United States)

    Kennea, J. A.; Lien, A. Y.; Krimm, H. A.; Cenko, S. B.; Siegel, M. H.

    2017-10-01

    At 02:37UT on October 3, 2017, Swift/BAT triggered on a source which was identified as a possible GRB or Galactic transient (Cenko et al., GCN #21960). Continued Swift observations showed that the source was at a constant X-ray brightness over 6 orbits, ruling out the GRB nature (Kennea et al., GCN #21963).

  2. THE SWIFT AGN AND CLUSTER SURVEY. II. CLUSTER CONFIRMATION WITH SDSS DATA

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Rhiannon D.; Dai, Xinyu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Kochanek, Christopher S. [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); Bregman, Joel N., E-mail: Rhiannon.D.Griffin-1@ou.edu, E-mail: xdai@ou.edu, E-mail: ckochanek@astronomy.ohio-state.edu, E-mail: jbregman@umich.edu [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-01-15

    We study 203 (of 442) Swift AGN and Cluster Survey extended X-ray sources located in the SDSS DR8 footprint to search for galaxy over-densities in three-dimensional space using SDSS galaxy photometric redshifts and positions near the Swift cluster candidates. We find 104 Swift clusters with a >3σ galaxy over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmation as galaxy clusters. We present a series of cluster properties including the redshift, brightest cluster galaxy (BCG) magnitude, BCG-to-X-ray center offset, optical richness, and X-ray luminosity. We also detect red sequences in ∼85% of the 104 confirmed clusters. The X-ray luminosity and optical richness for the SDSS confirmed Swift clusters are correlated and follow previously established relations. The distribution of the separations between the X-ray centroids and the most likely BCG is also consistent with expectation. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z ≲ 0.3 and is still 80% complete up to z ≃ 0.4, consistent with the SDSS survey depth. These analysis results suggest that our Swift cluster selection algorithm has yielded a statistically well-defined cluster sample for further study of cluster evolution and cosmology. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 23, and 1 matches in optical, X-ray, and Sunyaev–Zel’dovich catalogs, respectively, and so the majority of these clusters are new detections.

  3. Tidal disruption of stars by supermassive black holes: The X-ray view

    Directory of Open Access Journals (Sweden)

    Komossa S.

    2012-12-01

    Full Text Available The tidal disruption of stars by supermassive black holes produces luminous soft X-ray accretion flares in otherwise inactive galaxies. First events have been discovered in X-rays with the ROSAT observatory, and have more recently been detected with XMM-Newton, Chandra and Swift, and at other wavelengths. In X-rays, they typically appear as very soft, exceptionally luminous outbursts of radiation, which decline consistent with L ∝ t−5/3 on the timescale of months to years. They reach total amplitudes of decline up to factors 1000–6000 more than a decade after their initial high-states, and in low-state, their host galaxies are essentially X-ray inactive, optically inactive, and radio inactive. X-ray luminous tidal disruption events (TDEs represent a powerful new probe of accretion physics near the event horizon, and of relativistic effects. TDEs offer a new way of estimating black hole spin, and they are signposts of supermassive binary black holes and recoiling black holes. Once discovered in the thousands in upcoming sky surveys, their rates will probe stellar dynamics in distant galaxies, and they will uncover the – so far elusive – population of intermediate mass black holes in the universe, if they do exist. Further, the reprocessing of the flare into IR, optical and UV emission lines provides us with multiple new diagnostics of the properties of any gaseous material in the vicinity of the black hole (including the disrupted star itself and in the host galaxy. First candidate events of this kind have been reported recently.

  4. BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog

    Science.gov (United States)

    Ricci, C.; Trakhtenbrot, B.; Koss, M. J.; Ueda, Y.; Del Vecchio, I.; Treister, E.; Schawinski, K.; Paltani, S.; Oh, K.; Lamperti, I.; Berney, S.; Gandhi, P.; Ichikawa, K.; Bauer, F. E.; Ho, L. C.; Asmus, D.; Beckmann, V.; Soldi, S.; Baloković, M.; Gehrels, N.; Markwardt, C. B.

    2017-12-01

    Hard X-ray (≥10 keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The 70-month Swift/BAT all-sky survey, which probes the 14-195 keV energy range, has currently detected 838 AGNs. We report here on the broadband X-ray (0.3-150 keV) characteristics of these AGNs, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku observations in the soft X-ray band (≤slant 10 keV) with 70-month averaged Swift/BAT data. The nonblazar AGNs of our sample are almost equally divided into unobscured ({N}{{H}}X-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured AGNs.

  5. Leading-edge vortex lifts swifts.

    Science.gov (United States)

    Videler, J J; Stamhuis, E J; Povel, G D E

    2004-12-10

    The current understanding of how birds fly must be revised, because birds use their hand-wings in an unconventional way to generate lift and drag. Physical models of a common swift wing in gliding posture with a 60 degrees sweep of the sharp hand-wing leading edge were tested in a water tunnel. Interactions with the flow were measured quantitatively with digital particle image velocimetry at Reynolds numbers realistic for the gliding flight of a swift between 3750 and 37,500. The results show that gliding swifts can generate stable leading-edge vortices at small (5 degrees to 10 degrees) angles of attack. We suggest that the flow around the arm-wings of most birds can remain conventionally attached, whereas the swept-back hand-wings generate lift with leading-edge vortices.

  6. Provenance management in Swift with implementation details.

    Energy Technology Data Exchange (ETDEWEB)

    Gadelha, L. M. R; Clifford, B.; Mattoso, M.; Wilde, M.; Foster, I. (Mathematics and Computer Science); ( CLS-CI); (Federal Univ. of Rio de Janeiro); (National Lab. for Scientific Computing, Brazil); (Univ. of Chicago)

    2011-04-01

    The Swift parallel scripting language allows for the specification, execution and analysis of large-scale computations in parallel and distributed environments. It incorporates a data model for recording and querying provenance information. In this article we describe these capabilities and evaluate interoperability with other systems through the use of the Open Provenance Model. We describe Swift's provenance data model and compare it to the Open Provenance Model. We also describe and evaluate activities performed within the Third Provenance Challenge, which consisted of implementing a specific scientific workflow, capturing and recording provenance information of its execution, performing provenance queries, and exchanging provenance information with other systems. Finally, we propose improvements to both the Open Provenance Model and Swift's provenance system.

  7. Swift vs. Objective-C: A New Programming Language

    Directory of Open Access Journals (Sweden)

    Cristian González García

    2015-06-01

    In this article, we compare the new programming language of Apple, Swift, with the main programming language of Apple before Swift, Objective-C. We are going to show the differences, characteristics and novelties to verify the words of Apple about Swift. With that we want to answer the next question: Is Swift a new programming language easier, more secure and quicker to develop than Objective-C?

  8. IceCube-171106A: Swift observations

    Science.gov (United States)

    Keivani, A.; Fox, D. B.; DeLaunay, J. J.; Kennea, J. A.; Evans, P. A.; Cowen, D. F.; Osborne, J. P.; Marshall, F. E.; Swift-IceCube Collaboration

    2017-11-01

    Swift has observed the field of IceCube-171106A (Rev 0; subsequently updated to Rev 1, GCN #22105), utilizing the on-board 19-point tiling pattern to cover a region centered on RA,Dec (J2000) = (340.0d,+7.4d), with a radius of 0.8 & deg;.

  9. OpenStack Object Storage (Swift) essentials

    CERN Document Server

    Kapadia, Amar; Varma, Sreedhar

    2015-01-01

    If you are an IT administrator and you want to enter the world of cloud storage using OpenStack Swift, then this book is ideal for you. Basic knowledge of Linux and server technology is beneficial to get the most out of the book.

  10. Leading-Edge Vortex lifts swifts

    NARCIS (Netherlands)

    Videler, JJ; Stamhuis, EJ; Povel, GDE

    2004-01-01

    The current understanding of how birds fly must be revised, because birds use their hand-wings in an unconventional way to generate lift and drag. Physical models of a common swift wing in gliding posture with a 60degrees sweep of the sharp hand-wing leading edge were tested in a water tunnel.

  11. Swift Trust in Distributed Ad Hoc Teams

    Science.gov (United States)

    2007-10-04

    not visible or likely to be in close proximity . Page 22 Swift Trust in Distributed Ad hoc Teams Humansystems® mission ended, the servers were...simply allow less “ poetic license” when making judgements about other people. Perhaps asking about a more ambiguous behaviour or task would have yielded

  12. X-ray variability of serendipitous AGNs discovered in Swift GRB Fields

    Science.gov (United States)

    Turriziani, S.; Vagnetti, F.; Trevese, D.; Puccetti, S.; Giommi, P.; Perri, M.

    2008-10-01

    Active Galactic Nuclei are variable in all wave bands and in a wide range of time scales. In the X-ray band, short time scale (10^3-10^5 s) variability provides evidence that the emission comes from a compact region around the central supermassive black hole. In the optical bands the ensemble analysis on large optical samples was made possible by the Sloan Digital Sky Survey, and provided a characterization of the dependence of optical variability on luminosity, redshift, wavelength and time delay. A similar analysis can be performed in the X-rays, taking advantage of the catalogue of serendipitous sources extracted from ~230 SWIFT GRB fields, which contains about 7000 objects down to ~10^-15 erg/cm^2/s flux in the 0.5-10 keV band and ~800 objects down to 5x10^-14 erg/cm^2/s. The temporal sampling of Swift observations is designed to follow, in the X-ray band, the GRB evolution with typical intervals of a few days for a duration of weeks to months, and simultaneous UV-optical monitoring of the field. I will present preliminary results on the ensemble analysis of variability for a subsample of serendipitous sources with known redshift extracted from the Swift archive.

  13. How Swift is redefining time domain astronomy

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2015-09-01

    NASA's Swift satellite has completed ten years of amazing discoveries in time domain astronomy. Its primary mission is to chase gamma-ray bursts (GRBs), but due to its scheduling flexibility it has subsequently become a prime discovery machine for new types of behavior. The list of major discoveries in GRBs and other transients includes the long-lived X-ray afterglows and flares from GRBs, the first accurate localization of short GRBs, the discovery of GRBs at high redshift (z > 8), supernova shock break-out from SN Ib, a jetted tidal disruption event, an ultra-long class of GRBs, high energy emission from flare stars, novae and supernovae with unusual characteristics, magnetars with glitches in their spin periods, and a short GRB with evidence of an accompanying kilonova. Swift has developed a dynamic synergism with ground based observatories. In a few years gravitational wave observatories will come on-line and provide exciting new transient sources for Swift to study.

  14. Flash flood swift water rescues, Texas, 2005–2014

    OpenAIRE

    Vaidehi Shah; Katie R. Kirsch; Diana Cervantes; David F. Zane; Tracy Haywood; Jennifer A. Horney

    2017-01-01

    Although rainfall patterns are complex and difficult to predict, climate models suggest precipitation in Texas will occur less frequently and with greater intensity in the future. In combination with rapid population growth and development, extreme rainfall events are likely to lead to flash floods and necessitate swift water rescues. Swift water rescues are used to retrieve person(s) from swift water flowing at a rate of 1 knot or greater. Data were obtained from the Texas Fire Marshal’s Off...

  15. Femto-clock for the electron kinetics in swift heavy ion tracks

    Science.gov (United States)

    Medvedev, N.; Volkov, A. E.

    2017-11-01

    We propose a conceptual idea for developing a technique for the monitoring of transient states of the electronic system of materials irradiated with swift heavy ions (SHIs). The method is based on spectroscopic measurements of photon emission due to radiative decay of holes from different inner shells of ionized target atoms. Since a hole in each shell of each element decays with its own characteristic time, it potentially allows the extraction of femtosecond time-resolved information about the excited electronic system in the valence and conduction band of a target. We suggest that prior ion implantation could be used for constructing a selected time grid for this technique. We also discuss the shift of the ionization potentials in atoms multiple-ionized by a direct SHI impact that should allow us to distinguish the track core within a few angstroms around the ion trajectory from the periphery of a track.

  16. Lewis Swift celebrated comet hunter and the people's astronomer

    CERN Document Server

    Kronk, Gary W

    2017-01-01

    This biography covers the life of Lewis Swift (1820-1913), who discovered 13 comets and nearly 1,200 other deep sky objects. All 13 comets found by Swift now bear his name, including three periodic comets with periods of 6 years (11P/Tempel-Swift-LINEAR), 9 years (64P/Swift-Gehrels), and 133 years (109P/Swift-Tuttle). Swift's enthusiasm and success as an amateur astronomer helped make him famous in the United States. With the help of others, Swift was able to buy a 16-inch refractor, the third largest telescope in the United States at the time. Hulbert Harrington Warner built "Warner Observatory" to house this telescope. As a prolific writer and lecturer, Swift's stories appeared in newspapers and magazines, while his lectures showed that he was able to explain anything in a way that everyone could understand.  When Warner went broke during the "Panic of 1893," Swift was forced to leave his home. Almost two dozen invitations arrived from around the United States asking him to bring his telescope to their ci...

  17. ENRICHED BLACK HOLE ALGORITHM FOR DIMINUTION OF REAL POWER LOSS

    OpenAIRE

    Dr.K.Lenin

    2017-01-01

    This paper presents an Enriched Black Hole (EBH) algorithm for solving reactive power flow problem. The Black Hole Algorithm starts with a preliminary population of contestant and for all iteration of the black hole algorithm, the most excellent candidate is favored to be the black hole, which followed by pulling further candidates around it, called stars. If a star move very close to the black hole, it will be consumed by the black hole and is vanished undyingly. In such a case, a new star...

  18. Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925

    Science.gov (United States)

    Sakamoto, T.; Barbier, L.; Barthelmy, S. D.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; hide

    2010-01-01

    We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following observational burst properties: 1) galactic plane (b=-0.1 deg) localization, 2) 150 msec duration, and 3) a blackbody rather than a simple power-law spectral shape (with a significance level of 97%). We found two possible X-ray counterparts of GRB 050925 by comparing the X-ray images from Swift XRT and XMM-Newton. Both X-ray sources show the transient behavior with a power-law decay index shallower than -1. We found no hard X-ray emission nor any additional burst from the location of GRB 050925 in approximately 5 Ms of INTEGRAL data. We discuss about the three BATSE short bursts which might be associated with GRB 050925, based on their location and the duration. Assuming GRB 050925 is associated with the H(sub II), regions (W 58) at the galactic longitude of 1=70 deg, we also discuss the source frame properties of GRB 050925.

  19. Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

    Science.gov (United States)

    Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

    2017-07-01

    The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the

  20. Prompt Emission Properties of Swift GRBs

    Science.gov (United States)

    Sakamoto, T.; Barthelmy, S.; Baumgartner, W.; Cummings, J.; Fenimore, E.; Gehrels, N.; Krimm, H.; Markwardt, Craig B.; Palmer, D.; Parsons, A.; hide

    2010-01-01

    We present the results from the second Swift BAT catalog of 476 gamma-ray bursts, which contains bursts detected by the BAT between 2004 December 19 and 2009 December 21. In addition to the spectral and temporal parameters extracted from the first BAT GRB catalog, 3324 time-resolved spectra have been extracted and analyzed. We show and discuss 1) the duration distribution, 2) the hardness of short GRBs, 3) Epeak distribution, 4) the line of death problem and 5) an additional power-law component in the prompt emission spectrum.

  1. GLAST Prospects for Swift-Era Afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Gou, L.J.; /Penn State U., Astron. Astrophys.; Meszaros, P.; /Penn State U.

    2011-11-23

    We calculate the GeV spectra of gamma-ray burst afterglows produced by inverse Compton scattering of these objects sub-MeV emission. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant-parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST Large Area Telescope, as well as by AGILE.

  2. Gliding Swifts Attain Laminar Flow over Rough Wings

    NARCIS (Netherlands)

    Lentink, D.; De Kat, R.

    2014-01-01

    Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane

  3. Gliding swifts attain laminar flow over rough wings.

    Directory of Open Access Journals (Sweden)

    David Lentink

    Full Text Available Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1-2% of chord length on the upper surface--10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13% of their total area during glides that maximize flight distance and duration--similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance.

  4. Testing the blast wave model with Swift GRBs

    NARCIS (Netherlands)

    Curran, P.A.; Starling, R.L.C.; van der Horst, A.J.; Wijers, R.A.M.J.

    2009-01-01

    The complex structure of the light curves of Swift Gamma-Ray Bursts (GRBs) has made the identification of breaks, and the interpretation of the blast wave caused by the burst, more difficult than in the pre-Swift era. We aim to identify breaks, which are possibly hidden, and to constrain the blast

  5. Testing the blast wave model with Swift GRBs

    NARCIS (Netherlands)

    Curran, P.A.; Starling, R.L.C.; van der Horst, A.J.; Wijers, R.A.M.J.; de Pasquale, M.; Page, M.

    2011-01-01

    The complex structure of the light curves of Swift GRBs (e.g. superimposed flares and shallow decay) has made their interpretation and that of the blast wave caused by the burst, more difficult than in the pre-Swift era. We aim to constrain the blast wave parameters: electron energy distribution, p,

  6. Structural and electrical properties of swift heavy ion beam irradiated ...

    Indian Academy of Sciences (India)

    Synthesis of swift heavy ion induced metal silicide is a new advancement in materials science research. We have investigated the mixing at Co/Si interface by swift heavy ion beam induced irradiation in the electronic stopping power regime. Irradiations were undertaken at room temperature using 120 MeV Au ions at the ...

  7. SWiFT site atmospheric characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ennis, Brandon Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Historical meteorological tall tower data are analyzed from the Texas Tech University 200 m tower to characterize the atmospheric trends of the Scaled Wind Farm Technologies (SWiFT) site. In this report the data are analyzed to reveal bulk atmospheric trends, temporal trends and correlations of atmospheric variables. Through this analysis for the SWiFT turbines the site International Electrotechnical Commission (IEC) classification is determined to be class III-C. Averages and distributions of atmospheric variables are shown, revealing large fluctuations and the importance of understanding the actual site trends as opposed to simply using averages. The site is significantly directional with the average wind speed from the south, and particularly so in summer and fall. Site temporal trends are analyzed from both seasonal (time of the year) to daily (hour of the day) perspectives. Atmospheric stability is seen to vary most with time of day and less with time of year. Turbulence intensity is highly correlated with stability, and typical daytime unstable conditions see double the level of turbulence intensity versus that experienced during the average stable night. Shear, veer and atmospheric stability correlations are shown, where shear and veer are both highest for stable atmospheric conditions. An analysis of the Texas Tech University tower anemometer measurements is performed which reveals the extent of the tower shadow effects and sonic tilt misalignment.

  8. The Swift GRB Host Galaxy Legacy Survey

    Science.gov (United States)

    Perley, Daniel A.

    I will describe the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelengthprogram to characterize the demographics of the GRB host population and its redshift evolution from z=0 to z=7.Using unbiased selection criteria we have designated a subset of 119 Swift gamma-ray bursts which are now beingtargeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained andanalyzed, with major programs ongoing at Keck, GTC, Gemini, VLT, and Magellan to obtain complementaryoptical/NIR photometry and spectroscopy to enable full SED modeling and derivation of fundamental physicalparameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiasedmeasurement of the GRB host-galaxy luminosity and mass distributions and their evolution with redshift, compareGRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor andthe ability of GRBs to serve as tools for measuring and studying cosmic star-formation in the distant universe.

  9. GRBs in the Era of Swift and Fermi

    Science.gov (United States)

    Racusin, Judy

    2011-01-01

    Utilizing both Swift and Fermi to study GRBs provides us with a unique broad spectral and temporal window into both prompt emission and afterglow studies. Swift has provided key information from GRB follow-up of LAT detected bursts) that has led to ground-based redshift measurements and afterglow broadband light curves and SEDs. We study the X-ray and optical afterglows of Fermi-LAT detected bursts in the context of the hundreds of GRBs discovered by Swift over the last 7 years) in order to better understand the origin of the high-energy gamma-rays. We also briefly describe the efforts to best facilitate joint Swift-Fermi observations. These initial results demonstrate the synergy between Swift and Fermi) and hint at the many interesting discoveries to come.

  10. State-space Manifold and Rotating Black Holes

    CERN Document Server

    Bellucci, Stefano

    2010-01-01

    We study a class of fluctuating higher dimensional black hole configurations obtained in string theory/ $M$-theory compactifications. We explore the intrinsic Riemannian geometric nature of Gaussian fluctuations arising from the Hessian of the coarse graining entropy, defined over an ensemble of brane microstates. It has been shown that the state-space geometry spanned by the set of invariant parameters is non-degenerate, regular and has a negative scalar curvature for the rotating Myers-Perry black holes, Kaluza-Klein black holes, supersymmetric $AdS_5$ black holes, $D_1$-$D_5$ configurations and the associated BMPV black holes. Interestingly, these solutions demonstrate that the principal components of the state-space metric tensor admit a positive definite form, while the off diagonal components do not. Furthermore, the ratio of diagonal components weakens relatively faster than the off diagonal components, and thus they swiftly come into an equilibrium statistical configuration. Novel aspects of the scali...

  11. Long-term monitoring of Ark 120 with Swift

    Science.gov (United States)

    Gliozzi, M.; Papadakis, I. E.; Grupe, D.; Brinkmann, W. P.; Räth, C.

    2017-02-01

    We report the results of a six-month Swift monitoring campaign of Ark 120, a prototypical `bare' Seyfert 1 galaxy. The lack of intrinsic absorption combined with the nearly contemporaneous coverage of the ultraviolet (UV) and X-ray bands makes it possible to investigate the link between the accretion disc and the putative Comptonization corona. Our observations confirm the presence of substantial temporal variability, with the X-ray characterized by large-amplitude flux changes on time-scales of few days, while the variations in the UV bands are smoother and occur on time-scales of several weeks. The source also shows spectral variability with the X-ray spectrum steepening when the source is brighter. We do not detect any correlation between the UV flux and the X-ray spectral slope. A cross-correlation analysis suggests positive delays between X-rays and the UV emission, favouring a scenario of disc reprocessing. Although the strength of the correlation is moderate with a delay which is not well constrained (7.5 ± 7 d), it is nevertheless indicative of a very large disc reprocessing region, with a separation between the X-ray and the UV-emitting regions, which could be as large as 1000 rG. The Ark 120 correlation results are in agreement with those obtained in similar multiwavelength monitoring studies of active galactic nuclei (AGN). When combined together, the observations so far can be well described by a linear relation between the X-ray/UV delays and the mass of the central black hole. Within the context of the simplest scenario, where these delays correspond to light-travel times, the implied distance between the X-ray source and the optical/UV disc reprocessing region in these AGN should be of the order of many hundreds of gravitational radii.

  12. Supernova Classification Using Swift UVOT Photometry

    Science.gov (United States)

    Smith, Madison; Brown, Peter J.

    2017-01-01

    With the great influx of supernova discoveries over the past few years, the observation time needed to acquire the spectroscopic data needed to classify supernova by type has become unobtainable. Instead, using the photometry of supernovae could greatly reduce the amount of time between discovery and classification. For this project we looked at the relationship between colors and supernova types through machine learning packages in Python. Using data from the Swift Ultraviolet/Optical Telescope (UVOT), each photometric point was assigned values corresponding to colors, absolute magnitudes, and the relative times from the peak brightness in several filters. These values were fed into three classifying methods, the nearest neighbors, decision tree, and random forest methods. We will discuss the success of these classification systems, the optimal filters for photometric classification, and ways to improve the classification.

  13. OPTICAL VARIABILITY OF THE ACCRETION DISK AROUND THE INTERMEDIATE-MASS BLACK HOLE ESO 243-49 HLX-1 DURING THE 2012 OUTBURST

    Energy Technology Data Exchange (ETDEWEB)

    Webb, N. A.; Godet, O.; Barret, D. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Wiersema, K. [University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Lasota, J.-P. [Institut d' Astrophysique de Paris, UMR 7095, CNRS, UPMC Université Paris 06, 98bis Boulevard Arago, F-75014 Paris (France); Farrell, S. A. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia); Maccarone, T. J. [Department of Physics, Box 41051, Texas Tech University, Lubbock TX 79409-1051 (United States); Servillat, M., E-mail: natalie.webb@irap.omp.eu [Laboratoire AIM (CEA/DSM/IRFU/SAp, CNRS, Université Paris Diderot), CEA Saclay, Bat. 709, F-91191 Gif-sur-Yvette (France)

    2014-01-01

    We present dedicated quasi-simultaneous X-ray (Swift) and optical (Very Large Telescope, V-, and R-band) observations of the intermediate-mass black hole candidate HLX-1 before and during the 2012 outburst. We show that the V-band magnitudes vary with time, thus proving that a portion of the observed emission originates in the accretion disk. Using the first quiescent optical observations of HLX-1, we show that the stellar population surrounding HLX-1 is fainter than V ∼ 25.1 and R ∼ 24.2. We show that the optical emission may increase before the X-ray emission consistent with the scenario proposed by Lasota et al. in which the regular outbursts could be related to the passage at periastron of a star circling the intermediate-mass black hole in an eccentric orbit, which triggers mass transfer into a quasi-permanent accretion disk around the black hole. Further, if there is indeed a delay in the X-ray emission we estimate the mass-transfer delivery radius to be ∼10{sup 11} cm.

  14. Aerodynamics of gliding flight in common swifts.

    Science.gov (United States)

    Henningsson, P; Hedenström, A

    2011-02-01

    Gliding flight performance and wake topology of a common swift (Apus apus L.) were examined in a wind tunnel at speeds between 7 and 11 m s(-1). The tunnel was tilted to simulate descending flight at different sink speeds. The swift varied its wingspan, wing area and tail span over the speed range. Wingspan decreased linearly with speed, whereas tail span decreased in a nonlinear manner. For each airspeed, the minimum glide angle was found. The corresponding sink speeds showed a curvilinear relationship with airspeed, with a minimum sink speed at 8.1 m s(-1) and a speed of best glide at 9.4 m s(-1). Lift-to-drag ratio was calculated for each airspeed and tilt angle combinations and the maximum for each speed showed a curvilinear relationship with airspeed, with a maximum of 12.5 at an airspeed of 9.5 m s(-1). Wake was sampled in the transverse plane using stereo digital particle image velocimetry (DPIV). The main structures of the wake were a pair of trailing wingtip vortices and a pair of trailing tail vortices. Circulation of these was measured and a model was constructed that showed good weight support. Parasite drag was estimated from the wake defect measured in the wake behind the body. Parasite drag coefficient ranged from 0.30 to 0.22 over the range of airspeeds. Induced drag was calculated and used to estimate profile drag coefficient, which was found to be in the same range as that previously measured on a Harris' hawk.

  15. Evaluation of Swift Start TCP in Long-Delay Environment

    Science.gov (United States)

    Lawas-Grodek, Frances J.; Tran, Diepchi T.

    2004-01-01

    This report presents the test results of the Swift Start algorithm in single-flow and multiple-flow testbeds under the effects of high propagation delays, various slow bottlenecks, and small queue sizes. Although this algorithm estimates capacity and implements packet pacing, the findings were that in a heavily congested link, the Swift Start algorithm will not be applicable. The reason is that the bottleneck estimation is falsely influenced by timeouts induced by retransmissions and the expiration of delayed acknowledgment (ACK) timers, thus causing the modified Swift Start code to fall back to regular transmission control protocol (TCP).

  16. Beginning Swift games development for iOS

    CERN Document Server

    Goodwill, James

    2015-01-01

    Game apps are one of the most popular categories in the Apple iTunes App Store. Well, the introduction of the new Swift programming language will make game development even more appealing and easier to existing and future iOS app developers. In response, James Goodwill, Wesley Matlock and Apress introduce you to this book, Beginning Swift Games Development for iOS. In this book, you'll learn the fundamental elements of the new Swift language as applied to game development for iOS. In part 1, you'll start with a basic 2D game idea and build the game throughout the book introducing each Sprit

  17. Coronal Holes

    Directory of Open Access Journals (Sweden)

    Steven R. Cranmer

    2009-09-01

    Full Text Available Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations, and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are established in the extended corona. For example, the importance of kinetic plasma physics and turbulence in coronal holes has been affirmed by surprising measurements from the UVCS instrument on SOHO that heavy ions are heated to hundreds of times the temperatures of protons and electrons. These observations point to specific kinds of collisionless Alfvén wave damping (i.e., ion cyclotron resonance, but complete theoretical models do not yet exist. Despite our incomplete knowledge of the complex multi-scale plasma physics, however, much progress has been made toward the goal of understanding the mechanisms ultimately responsible for producing the observed properties of coronal holes.

  18. Optical photometry and Halpha Spectroscopy of SWIFT J1910.2-0546/MAXI J1910-057

    Science.gov (United States)

    Casares, Jorge; Rodriguez-Gil, Pablo; Zurita, Cristina; Corral-Santana, Jesus M.; Gonzalez Martinez-Pais, Ignacio; Corradi, Romano; Cornelisse, Remon; Charles, Phil A.

    2012-08-01

    We report on optical photometry and spectroscopy of the black hole X-ray transient Swift J1910.2-0546/MAXI J1910-057 (Krimm at al. ATel #4139, Usui et al. ATel #4140). R-band photometry (time resolution 27s) over an interval of 3.1 hr was obtained using ALFOSC on the 2.5m Nordic Optical Telescope (NOT) on the night of 21 July 2012. The light curve is dominated by flickering superimposed on a smooth, approximately sinusoidal variability of amplitude ~0.02 mags and ~4 hr time scale.

  19. The unusual X-ray emission of the short Swift GRB 090515: evidence for the formation of a magnetar?

    OpenAIRE

    Rowlinson, A.; O, P. T.; Tanvir, N. R.; Zhang, B.; Evans, P. A.; Lyons, N.; Levan, A. J.; Willingale, R.; Page, K. L.; Onal, O.; Burrows, D. N.; Beardmore, A. P.; Ukwatta, T. N.; Berger, Edo; Hjorth, J.

    2010-01-01

    The majority of short gamma-ray bursts (SGRBs) are thought to originate from the merger of compact binary systems collapsing directly to form a black hole. However, it has been proposed that both SGRBs and long gamma-ray bursts (LGRBs) may, on rare occasions, form an unstable millisecond pulsar (magnetar) prior to final collapse. GRB 090515, detected by the Swift satellite was extremely short, with a T_90 of 0.036 +/- 0.016 s, and had a very low fluence of 2 x 10^-8 erg cm^-2 and faint optica...

  20. Seattle wide-area information for travelers (SWIFT) : architecture study

    Science.gov (United States)

    1998-10-19

    The SWIFT (Seattle Wide-area Information For Travelers) Field Operational Test was intended to evaluate the performance of a large-scale urban Advanced Traveler Information System (ATIS) deployment in the Seattle area. The unique features of the SWIF...

  1. Sandia SWiFT Site Safe Work Planning Manual.

    Energy Technology Data Exchange (ETDEWEB)

    White, Jonathan

    2016-02-01

    The Department of Energy's Scaled Wind Farm Technology (SWiFT) facility provides research site with multiple wind turbines at a scale useful for the experimental study of wake dynamics, advanced rotor development, turbine control, and advanced sensing for production-scale wind farms. Safety of workers and the public is the top and overriding priority at SWiFT. Central to safe operations are formal planning processes . This manual provides an overview of test planning and work planning processes and requirements in adherence with the Sandia corporate Engineered Safety Work Planning and Control process. It is required reading for all SWiFT site staff, Sandia workers, and collaborators who oversee, conduct, or participate in test activities or who are involved in modifying Sandia SWiFT site assets.

  2. Correlative Analysis of GRBs Detected by Swift and Suzaku- WAM

    Science.gov (United States)

    Krimm, H.A.; Sakamoto, T.; Yamaoka, K.; Sugita, S.; Ohno, M.; Sato, G.; Hara, R.; Ohmori, N.; Tanaka, H.; Yamauchi, M.; hide

    2009-01-01

    It is now well known that a complete understanding of the energetics of the prompt phase of gamma-ray bursts (GRBs) requires full knowledge of the spectrum, extending at least as high as the peak energy (Epeak) of the vF(v) spectrum. Since most gamma-ray bursts (GRBs) have Epeak above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, a full understanding of the prompt emission from Swift GRBs requires spectral fits over as broad an energy range as possible. This can be completed for bursts which are simultaneously detected by Swift BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV. Between the launch of Suzaku in July 2005 and the end of 2008, there were 44 gamma-ray bursts (GRBs) which triggered both Swift and WAM and an additional 41 bursts which triggered Swift and were detected by WAM, but did not trigger. A joint BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters including Epeak. The results of broad spectral fits allows us to understand the distribution of Epeak for Swift bursts and to calibrate Epeak estimators when Epeak is within the BAT energy range. For those bursts with spectroscopic redshifts, we can calculate the isotropic energy and study various correlations between Epeak and other global burst parameters. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 77 of the bursts jointly detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.

  3. Time Domain Astronomy with Swift and Fermi

    African Journals Online (AJOL)

    J.D. Myers

    spectacular transient emission from tidal disruption events and supernova shock breakout. We present an overview of recent γ−ray and hard X-ray observations and discuss their impact on high-energy astrophysics. keywords: Black hole physics; radiation mechanisms: non-thermal;. Stars: activity; Gamma-ray burst: general; ...

  4. Quantum black holes

    CERN Document Server

    Calmet, Xavier; Winstanley, Elizabeth

    2014-01-01

    Written by foremost experts, this short book gives a clear description of the physics of quantum black holes. The reader will learn about quantum black holes in four and higher dimensions, primordial black holes, the production of black holes in high energy particle collisions, Hawking radiation, black holes in models of low scale quantum gravity and quantum gravitational aspects of black holes.

  5. NASA's Swift Satellite Catches First Supernova in The Act of Exploding

    Science.gov (United States)

    2008-05-01

    constellation Lynx. At 9:33 a.m. EST they spotted an extremely bright 5-minute X-ray outburst in NGC 2770. They quickly recognized that the X-rays were coming from another location in the same galaxy. People Who Read This Also Read... Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Chandra Data Reveal Rapidly Whirling Black Holes Ghostly Glow Reveals a Hidden Class of Long-Wavelength Radio Emitters In a paper submitted to Nature, Soderberg and 38 colleagues show that the energy and pattern of the X-ray outburst is consistent with a shock wave bursting through the surface of the progenitor star. This marks the birth of the supernova now known as SN 2008D. Although astronomers were lucky that Swift was observing NGC 2770 just at the moment when SN 2008D’s shock wave was blowing up the star, Swift is well equipped to study such an event because of its multiple instruments observing in gamma rays, X-rays, and ultraviolet light. "It was a gift of nature for Swift to be observing that patch of sky when the supernova exploded. But thanks to Swift's flexibility, we have been able to trace its evolution in detail every day since," says Swift lead scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md. Due to the significance of the X-ray outburst, Soderberg immediately mounted an international observing campaign to study SN 2008D. Observations were made with major telescopes such as the Hubble Space Telescope, the Chandra X-ray Observatory, the Very Large Array in New Mexico, the Gemini North telescope in Hawaii, the Keck I telescope in Hawaii, the 200-inch and 60-inch telescopes at the Palomar Observatory in California, and the 3.5-meter telescope at the Apache Point Observatory in New Mexico. The combined observations helped Soderberg and her colleagues pin down the energy of the initial X-ray outburst, which will help theorists better understand supernovae. The observations also show that SN 2008D is

  6. Jets, black holes and disks in blazars

    Directory of Open Access Journals (Sweden)

    Ghisellini Gabriele

    2013-12-01

    Full Text Available The Fermi and Swift satellites, together with ground based Cherenkov telescopes, has greatly improved our knowledge of blazars, namely Flat Spectrum Radio Quasars and BL Lac objects, since all but the most powerful emit most of their electro–magnetic output at γ–ray energies, while the very powerful blazars emit mostly in the hard X–ray region of the spectrum. Often they show coordinated variability at different frequencies, suggesting that in these cases the same population of electrons is at work, in a single zone of the jet. The location of this region along the jet is a matter of debate. The jet power correlates with the mass accretion rate, with jets existing at all values of disk luminosities, measured in Eddington units, sampled so far. The most powerful blazars show clear evidence of the emission from their disks, and this has revived methods of finding the black hole mass and accretion rate by modelling a disk spectrum to the data. Being so luminous, blazars can be detected also at very high redshift, and therefore are a useful tool to explore the far universe. One interesting line of research concerns how heavy are their black holes at high redshifts. If we associate the presence of a relativistic jets with a fastly spinning black hole, then we naively expect that the accretion efficiency is larger than for non–spinning holes. As a consequence, the black hole mass in jetted systems should grow at a slower rate. In turn, this would imply that, at high redshifts, the heaviest black holes should be in radio–quiet quasars. We instead have evidences of the opposite, challenging our simple ideas of how a black hole grows.

  7. Discovery of a tidal disruption event candidate from the 2XMM catalog

    Directory of Open Access Journals (Sweden)

    Farrell S.A.

    2012-12-01

    Full Text Available Stars approaching a supermassive black hole (SMBH can be tidally disrupted and subsequently accreted, providing a unique way to find and study inactive SMBHs. We report on our discovery of a new tidal disruption event candidate, 2XMMi J184725.1-631724, with unprecedented ultrasoft X-ray spectra near the flare peak. It lies toward the center of an inactive galaxy at z = 0.0353. It was detected serendipitously in two XMM-Newton observations separated by 211 days, with the flux increasing by a factor of ∼9. The source was not detected in X-rays by ROSAT in 1992, indicating a long-term variability factor of >64; neither by Swift in 2011, implying a flux decay factor of >12 since the last XMM-Newton observation. The XMM-Newton X-ray spectra are dominated by a strong cool thermal disk (>80%, tens of eV with the luminosity appearing to follow the L ∝ T4 relation, often seen in the thermal state of the BH X-ray binaries. Both XMM-Newton observations show large variability on timescales of hours. This can be explained as due to fast variations in the mass accretion rate, maybe caused by the shocks during the tidal disruption of the star.

  8. Selective binding of oligonucleotide on TiO{sub 2} surfaces modified by swift heavy ion beam lithography

    Energy Technology Data Exchange (ETDEWEB)

    Vicente Pérez-Girón, J. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Emerging Viruses Department Heinrich Pette Institute, Hamburg 20251 (Germany); Hirtz, M. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); McAtamney, C.; Bell, A.P. [Advanced Microscopy Laboratory, CRANN, Trinity College Dublin, Dublin 2 (Ireland); Antonio Mas, J. [Laboratorio de Genómica del Centro de Apoyo Tecnológico, Universidad Rey Juan Carlos, Campus de Alcorcón 28922, Madrid (Spain); Jaafar, M. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Luis, O. de [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Bioquímica, Fisiología y Genética Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Campus de Alcorcón, 28922 Madrid (Spain); Fuchs, H. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Physical Institute and Center for Nanotechnology (CeNTech), Wilhelm-Klemm-Straße 10, University of Münster (Germany); and others

    2014-11-15

    We have used swift heavy-ion beam based lithography to create patterned bio-functional surfaces on rutile TiO{sub 2} single crystals. The applied lithography method generates a permanent and well defined periodic structure of micrometre sized square holes having nanostructured TiO{sub 2} surfaces, presenting different physical and chemical properties compared to the surrounding rutile single crystal surface. On the patterned substrates selective binding of oligonucleotides molecules is possible at the surfaces of the holes. This immobilisation process is only being controlled by UV light exposure. The patterned transparent substrates are compatible with fluorescence detection techniques, are mechanically robust, have a high tolerance to extreme chemical and temperature environments, and apparently do not degrade after ten cycles of use. These qualities make the patterned TiO{sub 2} substrates useful for potential biosensor applications.

  9. EL FUTURO DE APPLE: SWIFT VERSUS OBJECTIVE-C

    Directory of Open Access Journals (Sweden)

    Cristian González García

    2015-12-01

    Full Text Available Hace unos meses Apple presentó un nuevo lenguaje de programación para sus plataformas: Swift. Con Swift, Apple pretende atraer a los programadores de los lenguajes de programación basados en la sintaxis de C++ y darles una mayor abstracción, que con Objective-C, para que sea más fácil programar para las plataformas de Apple. Por estas razones, se hace necesario contrastar lo pretendido por Apple y realizar un estudio del lenguaje de programación a fin de contrastar su objetivo. Para ello, se hicieron dos evaluaciones, una cualitativa y otra cuantitativa, con el propósito de verificar en qué medida Swift es un avance respecto a Objective-C.DThe Future of Apple: Swift Versus Objective-CABSTRACTFew months ago, Apple presented a new programming language: Swift. With Swift, Apple pretends to attract the programmers of the programming languages based on C++ syntax and gives them a higher abstraction than with Objective-C for being easier to programme to Apple’s platforms. For these reasons, it is necessary to contrast what is intended by Apple and do a study of the programming language to ascertain their goal. For this purpose, we did two evaluations, firstly a qualitative evaluation and after, a quantitative evaluation to verify in how much Swift is an advance with respect to Objective-C.Keywords: computer languages, computer programming, functional programming, object oriented programming, programming, software.

  10. DO THE FERMI GAMMA-RAY BURST MONITOR AND SWIFT BURST ALERT TELESCOPE SEE THE SAME SHORT GAMMA-RAY BURSTS?

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Eric; Briggs, Michael S. [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Connaughton, Valerie [Universities Space Research Association, Science and Technology Institute, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Lien, Amy [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Goldstein, Adam [NASA Postdoctoral Program, Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pelassa, Veronique [Smithsonian Astrophysical Observatory, P.O. Box 97, Amado, AZ 85645 (United States); Troja, Eleonora, E-mail: eb0016@uah.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-02-20

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  11. Machine-z: Rapid Machine-Learned Redshift Indicator for Swift Gamma-Ray Bursts

    Science.gov (United States)

    Ukwatta, T. N.; Wozniak, P. R.; Gehrels, N.

    2016-01-01

    Studies of high-redshift gamma-ray bursts (GRBs) provide important information about the early Universe such as the rates of stellar collapsars and mergers, the metallicity content, constraints on the re-ionization period, and probes of the Hubble expansion. Rapid selection of high-z candidates from GRB samples reported in real time by dedicated space missions such as Swift is the key to identifying the most distant bursts before the optical afterglow becomes too dim to warrant a good spectrum. Here, we introduce 'machine-z', a redshift prediction algorithm and a 'high-z' classifier for Swift GRBs based on machine learning. Our method relies exclusively on canonical data commonly available within the first few hours after the GRB trigger. Using a sample of 284 bursts with measured redshifts, we trained a randomized ensemble of decision trees (random forest) to perform both regression and classification. Cross-validated performance studies show that the correlation coefficient between machine-z predictions and the true redshift is nearly 0.6. At the same time, our high-z classifier can achieve 80 per cent recall of true high-redshift bursts, while incurring a false positive rate of 20 per cent. With 40 per cent false positive rate the classifier can achieve approximately 100 per cent recall. The most reliable selection of high-redshift GRBs is obtained by combining predictions from both the high-z classifier and the machine-z regressor.

  12. Unusual Swift-BAT Detected AGN

    Science.gov (United States)

    Hogg, James; Winter, L.

    2011-01-01

    The goals of our study were to analyze two odd AGN sources, NVSS 193013+341047 and IRAS 05218-1212, and determine if they were Compton-thick and low-redshift ERO analogs. The sources are strange because initial Swift XRT data lead us to believe the sources could be Compton-thick, typical of Seyfert 2 galaxies but they have broadlines in their optical spectra, typical of Seyfert 1 galaxies. These are two contradictory categorizations which made these sources very unique. In addition to the puzzling spectra, their SEDs are similar to the SED of a high redshift ERO and unlike things we typically see at their lower redshift. In order to study these sources further, we acquired and reduced higher quality XMM-Newton X-ray data. We then modeled the two spectra using XSPEC and learned that both sources had many complex components. From the higher quality data, we determined that they were heavily obscured, but not to the point of being considered Compton-thick. Both of the spectral fit models were heavily dependent on partial covering and reflection models. We found very high covering fractions and high column densities in both of our models, which was consistent with the galaxies being heavily obscured as we initially assumed. Further, we believe that future study of the sources as low-redshift ERO analogs can assist in better understanding of the early universe EROs we often see. If further study confirms the analogous relationship, these sources provide a great opportunity to add to our scientific knowledge about ERO evolution.

  13. Accelerating Medical Research using the Swift Workflow System

    Science.gov (United States)

    STEF-PRAUN, Tiberiu; CLIFFORD, Benjamin; FOSTER, Ian; HASSON, Uri; HATEGAN, Mihael; SMALL, Steven L.; WILDE, Michael; ZHAO, Yong

    2009-01-01

    Both medical research and clinical practice are starting to involve large quantities of data and to require large-scale computation, as a result of the digitization of many areas of medicine. For example, in brain research – the domain that we consider here – a single research study may require the repeated processing, using computationally demanding and complex applications, of thousands of files corresponding to hundreds of functional MRI studies. Execution efficiency demands the use of parallel or distributed computing, but few medical researchers have the time or expertise to write the necessary parallel programs. The Swift system addresses these concerns. A simple scripting language, SwiftScript, provides for the concise high-level specification of workflows that invoke various application programs on potentially large quantities of data. The Swift engine provides for the efficient execution of these workflows on sequential computers, parallel computers, and/or distributed grids that federate the computing resources of many sites. Last but not least, the Swift provenance catalog keeps track of all actions performed, addressing vital bookkeeping functions that so often cause difficulties in large computations. To illustrate the use of Swift for medical research, we describe its use for the analysis of functional MRI data as part of a research project examining the neurological mechanisms of recovery from aphasia after stroke. We show how SwiftScript is used to encode an application workflow, and present performance results that demonstrate our ability to achieve significant speedups on both a local parallel computing cluster and multiple parallel clusters at distributed sites. PMID:17476063

  14. Flash flood swift water rescues, Texas, 2005–2014

    Directory of Open Access Journals (Sweden)

    Vaidehi Shah

    2017-01-01

    Full Text Available Although rainfall patterns are complex and difficult to predict, climate models suggest precipitation in Texas will occur less frequently and with greater intensity in the future. In combination with rapid population growth and development, extreme rainfall events are likely to lead to flash floods and necessitate swift water rescues. Swift water rescues are used to retrieve person(s from swift water flowing at a rate of 1 knot or greater. Data were obtained from the Texas Fire Marshal’s Office and analyzed to describe spatial and temporal characteristics of rescues. Between 2005 and 2014, 3256 swift water rescues were reported from 136 of 254 (54% counties. Over half (54.6%, n = 1777 occurred in counties known as Flash Flood Alley, which includes Texas’ largest and fastest growing cities. Less than 1.0% (n = 18 were reported from 49 counties designated as completely rural, or with an urban population less than 2500. Increases in swift water rescues were seen between March and September and during major weather events such as tropical storms. Because county-level data was utilized and demographic data was missing in all but 2% (n = 47 of the incidents, our ability to identify populations at risk or target interventions in the future using this data is limited. Despite the frequency of flash flood events and swift water rescues in Texas, knowledge gaps persist that should be addressed through the conduct of interdisciplinary research by epidemiologists and climatologists and by disseminating evidence-based health education and safety programs, particularly in rapidly growing counties that make up Texas’ Flash Flood Alley.

  15. The Nature of the X-Ray Binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift Observations

    Science.gov (United States)

    Rodriquez, J.; Tomsick, J. A.; Bodaghee, A.; ZuritaHeras, J.-A.; Chaty, S.; Paizis, A.; Corbel, S.

    2009-01-01

    We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+ 1816. The Swift/XRT data allow us to refine the position of the source to R.A. (J2000) = 19h 29m 55.9s, Decl. (J2000) = +18 deg 18 feet 38 inches . 4 (+/- 3 inches .5), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard (Gamma approx 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsations at 12.43781 (+/- 0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+ 1816 being an high-mass X-ray binary (HMXB) with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implication of IGR J19294+1816 being an Supergiant Fast X-ray Transient (SFXT).

  16. The nature of the X-ray binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift observations

    Science.gov (United States)

    Rodriguez, J.; Tomsick, J. A.; Bodaghee, A.; Zurita Heras, J.-A.; Chaty, S.; Paizis, A.; Corbel, S.

    2009-12-01

    We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+1816. The Swift/XRT data allow us to refine the position of the source to {RA}J2000 = 19h 29m 55.9s {Dec}J2000 = +18° 18 arcmin38.4 arcsec (±3.5 arcsec), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard (Γ 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsation at 12.43781 (±0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+1816 being an HMXB with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short ( 2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implications of IGR J19294+1816 being an SFXT.

  17. Power Performance Test Report for the SWIFT Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, I.; Hur, J.

    2012-12-01

    This report summarizes the results of a power performance test that NREL conducted on the SWIFT wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the SWIFT is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

  18. EL FUTURO DE APPLE: SWIFT VERSUS OBJECTIVE-C

    OpenAIRE

    Cristian González García; Jordán Pascual Espada B.; Cristina Pelayo G-Bustelo; Juan Manuel Cueva Lovelle

    2015-01-01

    Hace unos meses Apple presentó un nuevo lenguaje de programación para sus plataformas: Swift. Con Swift, Apple pretende atraer a los programadores de los lenguajes de programación basados en la sintaxis de C++ y darles una mayor abstracción, que con Objective-C, para que sea más fácil programar para las plataformas de Apple. Por estas razones, se hace necesario contrastar lo pretendido por Apple y realizar un estudio del lenguaje de programación a fin de contrastar su objetivo. Para ello, se ...

  19. Implementing cloud storage with OpenStack Swift

    CERN Document Server

    Rajana, Kris; Varma, Sreedhar

    2014-01-01

    This tutorial-based book has a step-by-step approach for each topic, ensuring it is thoroughly covered and easy to follow. If you are an IT administrator who wants to enter the world of cloud storage using OpenStack Swift, then this book is ideal for you. Whether your job is to build, manage, or use OpenStack Swift, this book is an ideal way to move your career ahead. Only basic Linux and server technology skills are expected, to take advantage of this book.

  20. X-Ray Timing Measurements of NGC 5408 X-1 With XMM-Newton and Swift/XRT: Implications for the Mass of a ULX

    Science.gov (United States)

    Strohmayer, Tod E.

    2008-01-01

    I present new X-ray timing measurements of the ULX NGC 5408 X-1 with XMM-Newton, and long term monitoring with the XRT onboard SWIFT. This object is one of only two ULXs in which quasi-periodic oscillations (QPO) have been detected. Recent observations with XMM-Newton confirm the presence of QPOs in this object. Most interestingly, two QPOs are again detected, as in an earlier observation, however, the QPO frequencies are different, now appearing at 10 and approximately 14 mHz. We discuss the implications of the QPO frequencies and spectra at these two different epochs for the mass of the black hole in NGC 5408 X-1. We also present strong evidence for long term flux variations based on the SWIFT monitoring campaign.

  1. Advancing the Swift BAT All Sky Hard X-ray Survey to the NuSTAR and Astro-H Era

    Science.gov (United States)

    Koss, Michael

    We propose to re-start the processing of the Swift BAT hard X-ray survey which halted in 2010 due to a lack of funds. The additional five years of Swift will roughly double the exposure and include recent NuSTAR observations that provide a unique scientific opportunity to study: 1). the most Compton-thick AGN in the nearby universe, 2). longterm AGN variability above 10 keV, and 3). targeted searches for spectral features of supernova remnants and signatures of warm dark matter annihilation using stacking. Reprocessing the Swift Survey was recommended as an important task in the 2014 NASA Senior Review of missions where Swift was given the highest rating. We will also develop new software tools that should allow guest observers to access the BAT survey data in new and powerful ways to increase the scientific usefulness of the data. We will apply new techniques to increase the number of channels of the BAT spectra from 8 to finer resolutions for targeted spectroscopic searches (full resolution is 80 channels). We will also develop new software tools that allow time dependent spectral analysis of any catalog source, time and energy slices to produce an all sky source catalog, fluxes and upper limits for candidate hard X-ray sources chosen in another waveband, and the finally the ability to stack the BAT data for a pre-selected list of objects and energy bands.

  2. Galactic Black Hole Binaries: High-Energy Radiation

    National Research Council Canada - National Science Library

    Grove, J. E; Grindlay, J. E; Harmon, B. A; Hua, X. -M; Kazanas, D; McConnell, M

    1997-01-01

    Observations of galactic black hole candidates made by the instruments aboard the Compton GRO in the hard X-ray and gamma-ray bands have significantly enhanced our knowledge of the emission properties of these objects...

  3. Photoluminescence and Raman studies in swift heavy ion irradiated ...

    Indian Academy of Sciences (India)

    Photoluminescence and Raman studies in swift heavy ion irradiated polycrystalline aluminum oxide ... Polymers Volume 32 Issue 5 October 2009 pp 515-519 ... A broad photoluminescence (PL) emission with peak at ∼447 nm and two sharp emissions with peak at ∼ 679 and ∼ 695 nm are observed in pristine when ...

  4. The 105 month Swift-BAT data release

    Science.gov (United States)

    Oh, Kyuseok; Koss, Michael; Markwardt, Craig B.; Schawinski, Kevin; Baumgartner, Wayne H.; Barthelmy, Scott D.; Cenko, Bradley; Gehrels, Neil; Mushotzky, Richard; Petulante, Abigail; Ricci, Claudio; Lien, Amy; Trakhtenbrot, Benny; NASA GSFC Swift BAT team, BAT AGN Spectroscopic Survey (BASS)

    2018-01-01

    We present a new catalog of hard X-ray sources detected in the first 105 months of observations with the Burst Alert Telescope (BAT) on board the Swift observatory. The 105 month Swift-BAT survey is a uniform hard X-ray all-sky survey with a sensitivity of 8.40×10-12 erg s-1 cm-2 over 90% of the sky and 7.24×10-12 erg s-1 cm-2 over 50% of the sky in the 14‑195 keV band. The Swift-BAT 105 month catalog provides 1632 (422 new detections) hard X-ray sources in the 14 ‑ 195 keV band above the 4.8σ significance level. Adding to the previously known hard X-ray sources, 34% (144/422) of the new detections are identified as Seyfert AGN in nearby galaxies (z journal and at the Swift-BAT 105 month Web site.

  5. Egg morphology of Swift Terns in South Africa | Gaglio | Ostrich ...

    African Journals Online (AJOL)

    Morphology of Swift Tern Thalasseus bergii bergii eggs was examined on Robben Island, South Africa. A recently formed colony was found abandoned en masse, probably following human disturbance, and 146 freshly laid eggs were collected. The mean ± SD nest density was 7 ± 2.5 nests m-2 and 3% of nests contained ...

  6. MAXI J1535-571: Swift detection and localization

    Science.gov (United States)

    Kennea, J. A.; Evans, P. A.; Beardmore, A. P.; Krimm, H. A.; Romano, P.; Yamaoka, K.; Serino, M.; Negoro, H.

    2017-09-01

    As reported in GCN #21788, at 20:00:36UT Swift/BAT triggered on an outburst from a possible GRB (GRB 170902A) or, based upon its localization near the plane and the nature of the BAT trigger (long image trigger), a possible Galactic Transient.

  7. Structural and electrical properties of swift heavy ion beam irradiated ...

    Indian Academy of Sciences (India)

    Unknown

    search. We have investigated the mixing at Co/Si interface by swift heavy ion beam induced irradiation in the ... films are often employed in semiconductor technology and are used as ... rements at Co/Si interface were carried out online in the.

  8. Swift Confirmation of new transient activity in NGC 6440

    Science.gov (United States)

    Bahramian, A.; Kennea, J. A.; Altamirano, D.; Beri, Aru; Heinke, C. O.; Sivakoff, G. R.; Tetarenko, A. J.; Wijnands, Rudy; Degenaar, Nathalie

    2017-10-01

    Following report of enhanced X-ray brightness from the direction of the globular cluster NGC 6440 (ATel #10821), we observed this cluster on 2017-10-05 18:52:35 UT for 1.5 ks with Swift/XRT in Photon Counting mode.

  9. Photoluminescence and Raman studies in swift heavy ion irradiated ...

    Indian Academy of Sciences (India)

    Administrator

    Swift heavy ions (SHI) cause intense electronic excita- tions along the ion trajectory when they pass through material that may result in defect production or amorphiza- tion or phase transformation on nanometer scale (Bolse et al 2004; Wang et al 2004). Thus, it is interesting to know the effect of strong electronic excitation ...

  10. SWIFT: A Dynamical Model of Saccade Generation during Reading

    Science.gov (United States)

    Engbert, Ralf; Nuthmann, Antje; Richter, Eike M.; Kliegl, Reinhold

    2005-01-01

    Mathematical models have become an important tool for understanding the control of eye movements during reading. Main goals of the development of the SWIFT model (R. Engbert, A. Longtin, & R. Kliegl, 2002) were to investigate the possibility of spatially distributed processing and to implement a general mechanism for all types of eye movements…

  11. Time domain astronomy with Swift and Fermi | Gehrels | Rwanda ...

    African Journals Online (AJOL)

    Swift and Fermi are unveiling an unexpectedly rich tapestry of behavior in the transient γ−ray sky. Sources which were already known to be transient − such as pulsars, gamma-ray bursts, and blazars − have been studied in ever-increasing detail. For example, Fermi/LAT has detected 117 pulsars of which 56 are new.

  12. Black Holes Have Simple Feeding Habits

    Science.gov (United States)

    2008-06-01

    . "We thought this was the case, but up until now we haven't been able to nail it." People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Jet Power and Black Hole Assortment Revealed in New Chandra Image Chandra Data Reveal Rapidly Whirling Black Holes Ghostly Glow Reveals a Hidden Class of Long-Wavelength Radio Emitters The model that Markoff and her colleagues used to study the black holes includes a faint disk of material spinning around the black hole. This structure would mainly produce X-rays and optical light. A region of hot gas around the black hole would be seen largely in ultraviolet and X-ray light. A large contribution to both the radio and X-ray light comes from jets generated by the black hole. Multi-wavelength data is needed to disentangle these overlapping sources of light. "When we look at the data, it turns out that our model works just as well for the giant black hole in M81 as it does for the smaller guys," said Michael Nowak, a coauthor from the Massachusetts Institute of Technology. "Everything around this huge black hole looks just the same except it's almost 10 million times bigger." Among actively feeding black holes the one in M81 is one of the dimmest, presumably because it is "underfed". It is, however, one of the brightest as seen from Earth because of its relative proximity, allowing high quality observations to be made. "It seems like the underfed black holes are the simplest in practice, perhaps because we can see closer to the black hole," said Andrew Young of the University of Bristol in England. "They don't seem to care too much where they get their food from." This work should be useful for predicting the properties of a third, unconfirmed class called intermediate mass black holes, with masses lying between those of stellar and supermassive black holes. Some possible members of this class have been identified, but the evidence is controversial, so specific predictions for the

  13. Modeling the Swift Bat Trigger Algorithm with Machine Learning

    Science.gov (United States)

    Graff, Philip B.; Lien, Amy Y.; Baker, John G.; Sakamoto, Takanori

    2016-01-01

    To draw inferences about gamma-ray burst (GRB) source populations based on Swift observations, it is essential to understand the detection efficiency of the Swift burst alert telescope (BAT). This study considers the problem of modeling the Swift / BAT triggering algorithm for long GRBs, a computationally expensive procedure, and models it using machine learning algorithms. A large sample of simulated GRBs from Lien et al. is used to train various models: random forests, boosted decision trees (with AdaBoost), support vector machines, and artificial neural networks. The best models have accuracies of greater than or equal to 97 percent (less than or equal to 3 percent error), which is a significant improvement on a cut in GRB flux, which has an accuracy of 89.6 percent (10.4 percent error). These models are then used to measure the detection efficiency of Swift as a function of redshift z, which is used to perform Bayesian parameter estimation on the GRB rate distribution. We find a local GRB rate density of n (sub 0) approaching 0.48 (sup plus 0.41) (sub minus 0.23) per cubic gigaparsecs per year with power-law indices of n (sub 1) approaching 1.7 (sup plus 0.6) (sub minus 0.5) and n (sub 2) approaching minus 5.9 (sup plus 5.7) (sub minus 0.1) for GRBs above and below a break point of z (redshift) (sub 1) approaching 6.8 (sup plus 2.8) (sub minus 3.2). This methodology is able to improve upon earlier studies by more accurately modeling Swift detection and using this for fully Bayesian model fitting.

  14. Life inside black holes

    OpenAIRE

    Dokuchaev, V. I.

    2012-01-01

    We consider test planet and photon orbits of the third kind inside a black hole, which are stable, periodic and neither come out of the black hole nor terminate at the singularity. Interiors of supermassive black holes may be inhabited by advanced civilizations living on planets with the third-kind orbits. In principle, one can get information from the interiors of black holes by observing their white hole counterparts.

  15. From Black Holes to Quivers

    CERN Document Server

    Manschot, Jan; Sen, Ashoke

    2012-01-01

    Middle cohomology states on the Higgs branch of supersymmetric quiver quantum mechanics - also known as pure Higgs states - have recently emerged as possible microscopic candidates for single-centered black hole micro-states, as they carry zero angular momentum and appear to be robust under wall-crossing. Using the connection between quiver quantum mechanics on the Coulomb branch and the quantum mechanics of multi-centered black holes, we propose a general algorithm for reconstructing the full moduli-dependent cohomology of the moduli space of an arbitrary quiver, in terms of the BPS invariants of the pure Higgs states. We analyze many examples of quivers with loops, including all cyclic Abelian quivers and several examples with two loops or non-Abelian gauge groups, and provide supporting evidence for this proposal. We also develop methods to count pure Higgs states directly.

  16. NASA's Chandra Finds Youngest Nearby Black Hole

    Science.gov (United States)

    2010-11-01

    Astronomers using NASA's Chandra X-ray Observatory have found evidence of the youngest black hole known to exist in our cosmic neighborhood. The 30-year-old black hole provides a unique opportunity to watch this type of object develop from infancy. The black hole could help scientists better understand how massive stars explode, which ones leave behind black holes or neutron stars, and the number of black holes in our galaxy and others. The 30-year-old object is a remnant of SN 1979C, a supernova in the galaxy M100 approximately 50 million light-years from Earth. Data from Chandra, NASA's Swift satellite, the European Space Agency's XMM-Newton and the German ROSAT observatory revealed a bright source of X-rays that has remained steady during observation from 1995 to 2007. This suggests the object is a black hole being fed either by material falling into it from the supernova or a binary companion. "If our interpretation is correct, this is the nearest example where the birth of a black hole has been observed," said Daniel Patnaude of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. who led the study. The scientists think SN 1979C, first discovered by an amateur astronomer in 1979, formed when a star about 20 times more massive than the Sun collapsed. Many new black holes in the distant universe previously have been detected in the form of gamma-ray bursts (GRBs). However, SN 1979C is different because it is much closer and belongs to a class of supernovas unlikely to be associated with a GRB. Theory predicts most black holes in the universe should form when the core of a star collapses and a GRB is not produced. "This may be the first time the common way of making a black hole has been observed," said co-author Abraham Loeb, also of the Harvard-Smithsonian Center for Astrophysics. "However, it is very difficult to detect this type of black hole birth because decades of X-ray observations are needed to make the case." The idea of a black hole with

  17. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath

    Science.gov (United States)

    Mimica, P.; Giannios, D.; Metzger, B. D.; Aloy, M. A.

    2015-07-01

    We model the non-thermal transient Swift J1644+57 as resulting from a relativistic jet powered by the accretion of a tidally disrupted star on to a supermassive black hole. Accompanying synchrotron radio emission is produced by the shock interaction between the jet and the dense circumnuclear medium, similar to a gamma-ray burst afterglow. An open mystery, however, is the origin of the late-time radio re-brightening, which occurred well after the peak of the jetted X-ray emission. Here, we systematically explore several proposed explanations for this behaviour by means of multidimensional hydrodynamic simulations coupled to a self-consistent radiative transfer calculation of the synchrotron emission. Our main conclusion is that the radio afterglow of Swift J1644+57 is not naturally explained by a jet with a one-dimensional top-hat angular structure. However, a more complex angular structure comprised of an ultrarelativistic core (Lorentz factor Γ ˜ 10) surrounded by a slower (Γ ˜ 2) sheath provides a reasonable fit to the data. Such a geometry could result from the radial structure of the super-Eddington accretion flow or as the result of jet precession. The total kinetic energy of the ejecta that we infer of ˜ few 1053 erg requires a highly efficient jet launching mechanism. Our jet model providing the best fit to the light curve of the on-axis event Swift J1644+57 is used to predict the radio light curves for off-axis viewing angles. Implications for the presence of relativistic jets from tidal disruption events (TDEs) detected via their thermal disc emission, as well as the prospects for detecting orphan TDE afterglows with upcoming wide-field radio surveys and resolving the jet structure with long baseline interferometry, are discussed.

  18. A YOUNG MASSIVE STELLAR POPULATION AROUND THE INTERMEDIATE-MASS BLACK HOLE ESO 243-49 HLX-1

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, S. A. [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Servillat, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-67, Cambridge, MA 02138 (United States); Pforr, J.; Maraston, C. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Maccarone, T. J.; Knigge, C. [School of Physics and Astronomy, University of Southampton, Hampshire SO17 1BJ (United Kingdom); Godet, O.; Webb, N. A.; Barret, D.; Belmont, R. [Universite de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse (France); Gosling, A. J. [University of Oxford, Department of Physics, Keble Road, Oxford OX1 3RH (United Kingdom); Wiersema, K., E-mail: sean.farrell@sydney.edu.au [Department of Physics and Astronomy, University of Leicester, University Road, LE1 7RH Leicester (United Kingdom)

    2012-03-15

    We present Hubble Space Telescope and simultaneous Swift X-ray Telescope observations of the strongest candidate intermediate-mass black hole (IMBH) ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disk models, but is well described by a model comprised of an irradiated accretion disk plus a {approx}10{sup 6} M{sub Sun} stellar population. The age of the population cannot be uniquely constrained, with both young and old stellar populations allowed. However, the old solution requires excessive disk reprocessing and an extremely small disk, so we favor the young solution ({approx}13 Myr). In addition, the presence of dust lanes and the lack of any nuclear activity from X-ray observations of the host galaxy suggest that a gas-rich minor merger may have taken place less than {approx}200 Myr ago. Such a merger event would explain the presence of the IMBH and the young stellar population.

  19. Testing General Relativity with the Reflection Spectrum of the Supermassive Black Hole in 1H0707-495

    Science.gov (United States)

    Cao, Zheng; Nampalliwar, Sourabh; Bambi, Cosimo; Dauser, Thomas; García, Javier A.

    2018-02-01

    Recently, we have extended the x-ray reflection model relxill to test the spacetime metric in the strong gravitational field of astrophysical black holes. In the present Letter, we employ this extended model to analyze XMM-Newton, NuSTAR, and Swift data of the supermassive black hole in 1H0707-495 and test deviations from a Kerr metric parametrized by the Johannsen deformation parameter α13. Our results are consistent with the hypothesis that the spacetime metric around the black hole in 1H0707-495 is described by the Kerr solution.

  20. Correlative Analysis of GRBs detected by Swift, Konus and HETE

    Science.gov (United States)

    Krimm, Hans A.; Barthelmy, S. D.; Gehrels, N.; Hullinger, D.; Sakamoto, T.; Donaghy, T.; Lamb, D. Q.; Pal'shin, V.; Golenetskii, S.; Ricker, G. R.

    2005-01-01

    Swift has now detected a large enough sample of gamma-ray bursts (GRBs) to allow correlation studies of burst parameters. Such studies of earlier data sets have yielded important results leading to further understanding of burst parameters and classifications. This work focuses on seventeen Swift bursts that have also been detected either by Konus-Wind or HETE-II, providing high energy spectra and fits to E(sub peak). Eight of these bursts have spectroscopic redshifts and for others we can estimate redshifts using the variability/luminosity relationship. We can also compare E(sub peak) with E(sub iso), and for those bursts for which a jet break was observed in the afterglow we can derive E(sub g) and test the relationship between E(peak) and E(sub gamma). For all bursts we can derive durations and hardness ratios from the prompt emission.

  1. Massive Black Hole Binaries: Dynamical Evolution and Observational Signatures

    Directory of Open Access Journals (Sweden)

    M. Dotti

    2012-01-01

    Full Text Available The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here, we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries and of the candidates discussed in literature to date.

  2. INTEGRAL detection of SWIFT J2037.2+4151

    DEFF Research Database (Denmark)

    Westergaard, Niels Jørgen Stenfeldt; Budtz-Jørgensen, Carl; Chenevez, Jérôme

    2006-01-01

    The source detected by SWIFT (ATEL #853) was independently found in archived JEM-X public data in 5 pointings covering 18200s between 2004-07-19, 19:14 UTC and 2004-07-20, 03:27 UTC. Positioned within 1.2 degrees of Cyg X-3 it has been inside the JEM-X field-of-view more than 400 times with an of...

  3. Immobilization of swift foxes with ketamine hydrochloride-xylazine hydrochloride

    Science.gov (United States)

    Telesco, R.L.; Sovada, Marsha A.

    2002-01-01

    There is an increasing need to develop field immobilization techniques that allow researchers to handle safely swift foxes (Vulpes velox) with minimal risk of stress or injury. We immobilized captive swift foxes to determine the safety and effectiveness of ketamine hydrochloride and xylazine hydrochloride at different dosages. We attempted to determine appropriate dosages to immobilize swift foxes for an adequate field-handling period based on three anesthesia intervals (induction period, immobilization period, and recovery period) and physiologic responses (rectal temperature, respiration rate, and heart rate). Between October 1998–July 1999, we conducted four trials, evaluating three different dosage ratios of ketamine and xylazine (2.27:1.2, 5.68:1.2, and 11.4:1.2 mg/kg ketamine:mg/kg xylazine, respectively), followed by a fourth trial with a higher dosage at the median ratio (11.4 mg/kg ketamine:2.4 mg/kg xylazine). We found little difference in induction and recovery periods among trials 1–3, but immobilization time increased with increasing dosage (Pimmobilization period and recovery period increased in trial 4 compared with trials 1–3 (P≤0.03). There was a high variation in responses of individual foxes across trials, making it difficult to identify an appropriate dosage for field handling. Heart rate and respiration rates were depressed but all physiologic measures remained within normal parameters established for domestic canids. We recommend a dosage ratio of 10 mg/kg ketamine to 1 mg/kg xylazine to immobilize swift foxes for field handling.

  4. Learning iOS 8 game development using Swift

    CERN Document Server

    Shekar, Siddharth

    2015-01-01

    This book is for novices as well as proficient game developers who want to learn more about game development using Swift. If you are from a 2D game development background and would like to learn the basics of 3D game development, this book is for you. Additionally, if you want to learn the basics of graphics programming and shaders, this book will be a good starting point.

  5. Structural and electrical properties of swift heavy ion beam irradiated ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. The present work deals with the mixing of iron and silicon by swift heavy ions in high-energy range. The thin film was deposited on a n-Si (111) substrate at 10. –6 torr and at room temperature. Irradia- tions were undertaken at room temperature using 120 MeV Au. +9 ions at the Fe/Si interface to investigate ion.

  6. Beyond FMEA: the structured what-if technique (SWIFT).

    Science.gov (United States)

    Card, Alan J; Ward, James R; Clarkson, P John

    2012-01-01

    Although it is probably the best-known prospective hazard analysis (PHA) tool, failure mode and effects analysis (FMEA) is far from the only option available. This article introduces one of the alternatives: The structured what-if technique (SWIFT). SWIFT is a flexible, high-level risk identification technique that can be used on a stand-alone basis, or as part of a staged approach to make more efficient use of bottom-up methods like FMEA. In this article we describe the method, assess the evidence related to its use in healthcare with the use of a systematic literature review, and suggest ways in which it could be better adapted for use in the healthcare industry. Based on the limited evidence available, it appears that healthcare workers find it easy to learn, easy to use, and credible. Especially when used as part of a staged approach, SWIFT appears capable of playing a useful role as component of the PHA armamentarium. © 2012 American Society for Healthcare Risk Management of the American Hospital Association.

  7. Surfing a Black Hole

    Science.gov (United States)

    2002-10-01

    Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours [1] Summary An international team of astronomers [2], lead by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) , has directly observed an otherwise normal star orbiting the supermassive black hole at the center of the Milky Way Galaxy. Ten years of painstaking measurements have been crowned by a series of unique images obtained by the Adaptive Optics (AO) NAOS-CONICA (NACO) instrument [3] on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory. It turns out that earlier this year the star approached the central Black Hole to within 17 light-hours - only three times the distance between the Sun and planet Pluto - while travelling at no less than 5000 km/sec . Previous measurements of the velocities of stars near the center of the Milky Way and variable X-ray emission from this area have provided the strongest evidence so far of the existence of a central Black Hole in our home galaxy and, implicitly, that the dark mass concentrations seen in many nuclei of other galaxies probably are also supermassive black holes. However, it has not yet been possible to exclude several alternative configurations. In a break-through paper appearing in the research journal Nature on October 17th, 2002, the present team reports their exciting results, including high-resolution images that allow tracing two-thirds of the orbit of a star designated "S2" . It is currently the closest observable star to the compact radio source and massive black hole candidate "SgrA*" ("Sagittarius A") at the very center of the Milky Way. The orbital period is just over 15 years. The new measurements exclude with high confidence that the central dark mass consists of a cluster of unusual stars or elementary particles, and leave little doubt of the presence of a supermassive black hole at the centre of the galaxy in which we live . PR Photo 23a/02 : NACO image of the central region of the Milky Way

  8. Higher spin black holes

    National Research Council Canada - National Science Library

    Gutperle, Michael; Kraus, Per

    2011-01-01

    .... We find solutions that generalize the BTZ black hole and carry spin-3 charge. The black hole entropy formula yields a result for the asymptotic growth of the partition function at finite spin-3 chemical potential...

  9. Magnetic fields threading black holes: restrictions from general relativity and implications for astrophysical black holes

    Science.gov (United States)

    Garofalo, David

    2017-07-01

    The idea that black hole spin is instrumental in the generation of powerful jets in active galactic nuclei and X-ray binaries is arguably the most contentious claim in black hole astrophysics. Because jets are thought to originate in the context of electromagnetism, and the modeling of Maxwell fields in curved spacetime around black holes is challenging, various approximations are made in numerical simulations that fall under the guise of `ideal magnetohydrodynamics'. But the simplifications of this framework may struggle to capture relevant details of real astrophysical environments near black holes. In this work, we highlight tension between analytic and numerical results, specifically between the analytically derived conserved Noether currents for rotating black hole spacetimes and the results of general relativistic numerical simulations (GRMHD). While we cannot definitively attribute the issue to any specific approximation used in the numerical schemes, there seem to be natural candidates, which we explore. GRMHD notwithstanding, if electromagnetic fields around rotating black holes are brought to the hole by accretion, we show from first principles that prograde accreting disks likely experience weaker large-scale black hole-threading fields, implying weaker jets than in retrograde configurations.

  10. Monopole black hole skyrmions

    OpenAIRE

    Moss, I.G.; Shiiki, N.; Winstanley, E.

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  11. Swift confirms BL Lacertae in an historic high state in the Optical/UV

    Science.gov (United States)

    Grupe, Dirk; Wehrle, Ann; Jorstad, Svetlana

    2013-11-01

    We report on an unprecedented high flux in the Optical/UV in BL Lacertae (22h 02m 43a, +42d 16m 40s) seen by Swift on 2013 November 22, confirming findings by Larionov et al. (ATEL #5597) in the R band. We are currently monitoring BL Lac with Swift twice a week. Swift UVOT observed BL Lacertae in all 6 filters. Over the last half year BL Lac has become increasingly brighter in all 6 UVOT filters.

  12. Finding Free-Floating Black Holes using Astrometric Microlensing

    Science.gov (United States)

    Lu, Jessica R.; Ofek, Eran Oded; Sinukoff, Evan; Udalski, Andrzej; Kozlowski, Szymon

    2017-01-01

    Our Galaxy most likely hosts 10-100 million stellar mass black holes. The exact number and mass function of these black holes contains important information regarding our Galaxy's star formation history, stellar mass function, and the fate of very massive stars. However, isolated stellar black holes have yet to be detected. To date, stellar mass black holes have only been definitively detected in binary systems with accreting companions or merging to produce gravitational waves. In principle, the presence of isolated black holes can be inferred from astrometric and photometric signatures produced when they lens light from a background star. We attempt to detect the astrometric lensing signatures of several photometrically identified microlensing events, toward the Galactic Bulge. Long-duration events (t_Einstein > 100 days) were selected as the most likely black hole candidates and were observed using several years of laser-guided adaptive optics observations from the W. M. Keck telescopes. We present results from this search.

  13. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  14. Charged cosmological black hole

    Science.gov (United States)

    Moradi, Rahim; Stahl, Clément; Firouzjaee, Javad T.; Xue, She-Sheng

    2017-11-01

    The cosmological black holes are black holes living not in an asymptotically flat universe but in an expanding spacetime. They have a rich dynamics especially for their mass and horizon. In this article, we perform a natural step in investigating this new type of black hole: we consider the possibility of a charged cosmological black hole. We derive the general equations of motion governing its dynamics and report a new analytic solution for the special case of the charged Lematre-Tolman-Bondi equations of motion that describe a charged cosmological black hole. We then study various relevant quantities for the characterization of the black hole, such as the C-function, the effect of the charge on the black hole flux, and the nature of the singularity. We also perform numerical investigations to strengthen our results. Finally, we challenge a model of gamma ray burst within our framework.

  15. Swift/XRT localization of IGR J19149+1036

    Science.gov (United States)

    Bozzo, E.; Ferrigno, C.; Pavan, L.; Walter, R.; Stella, L.

    2011-05-01

    The field around the recently discovered IGR J19149+1036 (Pavan et al., 2011, A&A, 526, 122) was observed by Swift/XRT twice, on 2010 Dec. 5 and 2011 Feb. 17. The total exposure time was 2.1 ks. In both observations, a single point-like source was detected within the IBIS/ISGRI error circle. By summing up all the available XRT data we estimated the best position at: RA = 19h14m56.73s Dec = +10:36:38.11 (J2000), with an associated uncertainty of 3.7 arcsec.

  16. Systematic Spectral Lag Analysis of Swift Known-z GRBs

    Directory of Open Access Journals (Sweden)

    Yuta Kawakubo

    2015-01-01

    arrive earlier than soft photons. The lag-luminosity relation is the empirical relationship between the isotropic peak luminosity and the spectral lag. We calculated the spectral lags for 40 known redshift GRBs observed by Swift addition to the previous 31 GRB samples. We confirmed that most of our samples follow the lag-luminosity relation. However, we noticed that there are some GRBs which show a significant scatter from the relation. We also confirm that the relationship between the break time and the luminosity of the X-ray afterglow (so-called Dainotti relation extends up to the lag-luminosity relation.

  17. Calibration of the Swift-UVOT ultraviolet and visible grisms

    OpenAIRE

    Kuin, N. P. M.; Landsman, W.; Breeveld, A. A.; Page, M. J.; Lamoureux, H.; James, C.; Mehdipour, M.; Still, M.; Yershov, V.; Brown, P.J.; Carter, M; Mason, K. O.; Kennedy, T.; Marshall, F.; Roming, P. W. A.

    2015-01-01

    We present the calibration of the Swift Ultraviolet and Optical Telescope (UVOT ) grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands, respectively. The UV grism covers the range λ1700–5000 Å with a spectral resolution (λ/Δλ) of 75 at λ2600 Å for source magnitudes of u=10–16 mag, while the visible grism covers the range λ2850–6600 Å with a spectral resolution of 100 at λ4000 Å for source magnitudes of b=12–17 mag. This calibration e...

  18. The Swift-UVOT ultraviolet and visible grism calibration

    OpenAIRE

    Kuin, N. P. M.; Landsman, W.; Breeveld, A. A.; Page, M. J.; James, C.; Lamoureux, H.; Mehdipour, M.; Still, M.; Yershov, V.; Brown, P.J.; Carter, M; Mason, K. O.; Kennedy, T.; Marshall, F.; Roming, P. W. A.

    2015-01-01

    We present the calibration of the Swift UVOT grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands respectively. The UV grism covers the range 1700-5000 Angstrom with a spectral resolution of 75 at 2600 Angstrom for source magnitudes of u=10-16 mag, while the visible grism covers the range 2850-6600 Angstrom with a spectral resolution of 100 at 4000 Angstrom for source magnitudes of b=12-17 mag. This calibration extends over all detec...

  19. Stimulated Black Hole Evaporation

    CERN Document Server

    Spaans, Marco

    2016-01-01

    Black holes are extreme expressions of gravity. Their existence is predicted by Einstein's theory of general relativity and is supported by observations. Black holes obey quantum mechanics and evaporate spontaneously. Here it is shown that a mass rate $R_f\\sim 3\\times 10^{-8} (M_0/M)^{1/2}$ $M_0$ yr$^{-1}$ onto the horizon of a black hole with mass $M$ (in units of solar mass $M_0$) stimulates a black hole into rapid evaporation. Specifically, $\\sim 3 M_0$ black holes can emit a large fraction of their mass, and explode, in $M/R_f \\sim 3\\times 10^7 (M/M_0)^{3/2}$ yr. These stimulated black holes radiate a spectral line power $P \\sim 2\\times 10^{39} (M_0/M)^{1/2}$ erg s$^{-1}$, at a wavelength $\\lambda \\sim 3\\times 10^5 (M/M_0)$ cm. This prediction can be observationally verified.

  20. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  1. Microlensing Signature of Binary Black Holes

    Science.gov (United States)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  2. Hole crystallization in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bonitz, M [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Filinov, V S [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet Kiel, 24098 Kiel (Germany); Fortov, V E [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Levashov, P R [Institute for High Energy Density, Russian Academy of Sciences, Izhorskay 13/19, Moscow 127412 (Russian Federation); Fehske, H [Institut fuer Physik, Universitaet Greifswald, l7487 Greifswald (Germany)

    2006-04-28

    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  3. Hole crystallization in semiconductors

    OpenAIRE

    Bonitz, M.; Filinov, V. S.; Fortov, V. E.; Levashov, P. R.; Fehske, H.

    2005-01-01

    When electrons in a solid are excited to a higher energy band they leave behind a vacancy (hole) in the original band which behaves like a positively charged particle. Here we predict that holes can spontaneously order into a regular lattice in semiconductors with sufficiently flat valence bands. The critical hole to electron effective mass ratio required for this phase transition is found to be of the order of 80.

  4. Hyperaccreting Black Hole as Gamma-Ray Burst Central Engine. II. Temporal Evolution of the Central Engine Parameters during the Prompt and Afterglow Phases

    Science.gov (United States)

    Lei, Wei-Hua; Zhang, Bing; Wu, Xue-Feng; Liang, En-Wei

    2017-11-01

    A hyperaccreting stellar-mass black hole (BH) has been proposed as the candidate central engine of gamma-ray bursts (GRBs). The rich observations of GRBs by Fermi and Swift make it possible to constrain the central engine model by comparing the model predictions against data. This paper is dedicated to studying the temporal evolution of the central engine parameters for both the prompt emission and afterglow phases. We consider two jet-launching mechanisms, i.e., ν \\bar{ν } annihilations and the Blandford–Znajek (BZ) process, and obtain analytical solutions to these two models. We then investigate the BH central engine parameters, such as the jet power, the dimensionless entropy η, and the central engine parameter μ 0 = η (1 + σ 0) (where σ 0 is the initial magnetization of the engine) at the base of the jet. The BH may be spun up by accretion or spun down by the BZ process, leaving imprints in the GRB light curves. Usually, a BZ jet is more powerful and is likely responsible for the late-time central engine activities. However, an initially non-spinning BH central engine may first launch a thermal “fireball” via neutrino annihilations, and then launch a Poynting-flux-dominated jet via the BZ process. Multiple flares, giant bumps, and plateaus in GRB afterglows can be produced as the result of late-time accretion onto the BH.

  5. Chandra and NuSTAR Follow-up Observations of Swift-BAT-selected AGNs

    Science.gov (United States)

    Marchesi, S.; Tremblay, L.; Ajello, M.; Marcotulli, L.; Paggi, A.; Cusumano, G.; La Parola, V.; Segreto, A.

    2017-10-01

    Based on current models of the cosmic X-ray background (CXB), heavily obscured active galactic nuclei (AGNs) are expected to make up ˜10% of the peak emission of the CXB and ˜20% of the total population of AGNs, yet few of these sources have been recorded and characterized in current surveys. Here we present the Chandra follow-up observation of 14 AGNs detected by Swift-BAT. For five sources in the sample, NuSTAR observations in the 3-80 keV band are also available. The X-ray spectral fitting over the 0.3-150 keV energy range allows us to determine the main X-ray spectral parameters, such as the photon index and the intrinsic absorption, of these objects and to make hypotheses on the physical structures responsible for the observed spectra. We find that 13 of the 14 objects are absorbed AGNs, and one is a candidate Compton-thick AGN, having intrinsic absorption {N}{{H}}> {10}24 cm-2. Finally, we verified that the use of NuSTAR observations is strategic to strongly constrain the properties of obscured AGNs, since the best-fit values we obtained for parameters such as the power-law photon index Γ and the intrinsic absorption {N}{{H}} changed sometimes significantly fitting the spectra with and without the use of NuSTAR data.

  6. Joint Swift XRT and NuSTAR Observations of TXS 0506+056

    Science.gov (United States)

    Fox, D. B.; DeLaunay, J. J.; Keivani, A.; Evans, P. A.; Turley, C. F.; Kennea, J. A.; Cowen, D. F.; Osborne, J. P.; Santander, M.; Marshall, F. E.

    2017-10-01

    We have carried out joint Swift and NuSTAR observations of the BL Lac-type blazar TXS 0506+056, identified in our previous Swift XRT observations (GCN #21930) as one of nine bright X-ray sources within the localization region of the likely-cosmic IceCube EHE neutrino IceCube-170922A (GCN #21916).

  7. Swift-XRT globular cluster monitor: April 2016 Terzan 5 observations

    Science.gov (United States)

    Linares, M.; Chenevez, J.

    2016-04-01

    As part of our Swift-XRT monitoring program of Galactic globular clusters, publicly available here, Swift observed Terzan 5 on 2016 April 17 for 3.2 ksec. Two additional 1.5-ksec-long observations were taken on April 21 and 23 (ATel #8982).

  8. Swift detection of the second period derivative in the timing evolution of SGR0501+4516

    NARCIS (Netherlands)

    Israel, G.L.; Woods, P.; Dall'Osso, S.; Esposito, P.; Rea, N.; Kouveliotou, C.; Gogus, E.; Mangano, V.; Romano, P.; Palmer, D.; Gehrels, N.; Stella, L.; Zane, S.

    2008-01-01

    The Swift satellite has been monitoring SGR0501+4516 (ATel #1676, #1677, #1678, #1682, #1683, #1688, #1691, #1692 and #1824) since the first burst detected by the BAT on board Swift on 22nd August 2008. After about two months since the BAT event, we detect an additional component with respect to the

  9. Full vehicle ABS braking using the SWIFT rigid ring tyre model

    NARCIS (Netherlands)

    Pauwelussen, J.P.; Gootjes, L.; Schröder, C.; Köhne, K.-U.; Jansen, S.T.H.; Schmeitz, A.J.C.

    2003-01-01

    In recent years, at the Delft University of Technology and TNO-Automotive and in conjunction with an industrial consortium, a pragmatic tyre model has been developed going by the name SWIFT, which is geared to the analysis of tyre oscillations and its effects on vehicle behaviour. The SWIFT tyre

  10. From Adam Swift to Adam Smith: How the "Invisible Hand" Overcomes Middle Class Hypocrisy

    Science.gov (United States)

    Tooley, James

    2007-01-01

    This paper challenges Richard Pring's suggestion that parents using private education may be undermining the desire for social justice and equality, using recent arguments of Adam Swift as a springboard. Swift's position on the banning of private schools, which uses a Rawlsian "veil of ignorance" argument, is explored, and it is suggested that, if…

  11. Full vehicle ABS braking using the SWIFT rigid ring tyre model

    NARCIS (Netherlands)

    Jansen, S.; Pauwelussen, J.P.; Gootjes, L.; Schröder, C.

    2000-01-01

    In recent years, at the Delft University of Technology and TNO Automotive and in conjuction with an industrial consortium, a pragmatic tyre model has been developed going by the name SWIFT, which is geared to the analysis of tyre oscillations and its effects on vehicle behaviour. The SWIFt tyre

  12. Asymptotic black holes

    Science.gov (United States)

    Ho, Pei-Ming

    2017-04-01

    Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.

  13. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    Science.gov (United States)

    Racusin, Judith L.; Oates, S. R.; Schady, P.; Burrows, D. N.; dePasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; hide

    2011-01-01

    The new and extreme population of GRBs detected by Fermi -LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust dataset of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT detected GRBs and the well studied, fainter, less energetic GRBs detected by Swift -BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi -GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  14. Dislocation loop formation by swift heavy ion irradiation of metals

    Science.gov (United States)

    Khara, Galvin S.; Murphy, Samuel T.; Duffy, Dorothy M.

    2017-07-01

    A coupled two-temperature, molecular dynamics methodology is used to simulate the structural evolution of bcc metals (Fe and W) and fcc metals (Cu and Ni) following irradiation by swift heavy ions. Electronic temperature dependent electronic specific heat capacities and electron-phonon coupling strengths are used to capture the full effects of the variation in the electronic density of states. Tungsten is found to be significantly more resistant to damage than iron, due both to the higher melting temperature and the higher thermal conductivity. Very interesting defect structures, quite different from defects formed in cascades, are found to be created by swift heavy ion irradiation in the bcc metals. Isolated vacancies form a halo around elongated interstitial dislocation loops that are oriented along the ion path. Such configurations are formed by rapid recrystallization of the molten cylindrical region that is created by the energetic ion. Vacancies are created at the recrystallization front, resulting in excess atoms at the core which form interstitial dislocation loops on completion of crystallization. These unique defect structures could, potentially, be used to create metal films with superior mechanical properties and interesting nanostructures.

  15. Characterization of swift heavy ion irradiation damage in ceria

    Energy Technology Data Exchange (ETDEWEB)

    Yablinsky, Clarissa; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, T. R.

    2015-05-14

    We have examined microstructural evolution in irradiated ceria (CeO2) using swift heavy ion irradiation, electron microscopy, and atomistic simulation. CeO2, a UO2 fuel surrogate, was irradiated with gold ions at an energy of 1 GeV to fluences up to 1x1014 ions/cm2. Transmission electron microscopy accompanied by electron energy loss spectroscopy showed that the ion tracks were of similar size at all fluences, and that there was no chemical change in the ion track core. Classical molecular dynamics simulations of thermal spikes in CeO2 with energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at the lower energy and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  16. Characterization of swift heavy ion irradiation damage in ceria

    Energy Technology Data Exchange (ETDEWEB)

    Yablinsky, Clarissa A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devanathan, Ram [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pakarinen, Janne [Inst. for Nuclear Research Center (SCK-CEN), Mol, (Belgium); Gan, Jian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Severin, Daniel [GSI-Darmstadt (Germany); Trautmann, Christina [GSI-Darmstadt (Germany); Allen, Todd R. [Univ. of Wisconsin, Madison, WI (United States). Energy Physics Dept.

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  17. Wake potential of swift ion in amorphous carbon target

    Science.gov (United States)

    Al-Bahnam, Nabil janan; Ahmad, Khalid A.; Aboo Al-Numan, Abdullah Ibrahim

    2017-02-01

    The wake potential and wake phenomena for swift proton in an amorphous carbon target were studied by utilising various dielectric function formalisms, including the Drude dielectric function, the Drude-Lorentz dielectric function and quantum dielectric function. The Drude model results exhibited a damped oscillatory behaviour in the longitudinal direction behind the projectile; the pattern of these oscillations decreases exponentially in the transverse direction. In addition, the wake potential extends slightly ahead of the projectile which also depends on the proton coordinate and velocity. The effect of electron binding on the wake potential, characterised by the ratio ωp2/ω02 = 10 to 0.1, has been studied alongside the Drude-Lorentz dielectric function and quantum dielectric function formalisms; the results evidently show that the wake potential dip depth decreases with more oscillations when the electron density ratio ωp2/ω02 decreases from 10 to 0.1. One of the primary objectives of the present work is to construct a reasonably realistic procedure for simulating the response of target to swift ions by combining an expression for the induced wake potential along with several important dielectric function models; the aim of this research is to reduce computational complexity without sacrificing accuracy. This is regarded as being an efficient strategy in that it creates suitable computer simulation procedures which are relevant to actual solids. After comparing this method with other models, the main differences and similarities have been noted while the end results have proved encouraging.

  18. Black Hole Hunters Set New Distance Record

    Science.gov (United States)

    2010-01-01

    Astronomers using ESO's Very Large Telescope have detected, in another galaxy, a stellar-mass black hole much farther away than any other previously known. With a mass above fifteen times that of the Sun, this is also the second most massive stellar-mass black hole ever found. It is entwined with a star that will soon become a black hole itself. The stellar-mass black holes [1] found in the Milky Way weigh up to ten times the mass of the Sun and are certainly not be taken lightly, but, outside our own galaxy, they may just be minor-league players, since astronomers have found another black hole with a mass over fifteen times the mass of the Sun. This is one of only three such objects found so far. The newly announced black hole lies in a spiral galaxy called NGC 300, six million light-years from Earth. "This is the most distant stellar-mass black hole ever weighed, and it's the first one we've seen outside our own galactic neighbourhood, the Local Group," says Paul Crowther, Professor of Astrophysics at the University of Sheffield and lead author of the paper reporting the study. The black hole's curious partner is a Wolf-Rayet star, which also has a mass of about twenty times as much as the Sun. Wolf-Rayet stars are near the end of their lives and expel most of their outer layers into their surroundings before exploding as supernovae, with their cores imploding to form black holes. In 2007, an X-ray instrument aboard NASA's Swift observatory scrutinised the surroundings of the brightest X-ray source in NGC 300 discovered earlier with the European Space Agency's XMM-Newton X-ray observatory. "We recorded periodic, extremely intense X-ray emission, a clue that a black hole might be lurking in the area," explains team member Stefania Carpano from ESA. Thanks to new observations performed with the FORS2 instrument mounted on ESO's Very Large Telescope, astronomers have confirmed their earlier hunch. The new data show that the black hole and the Wolf-Rayet star dance

  19. Primordial Black Holes: sirens of the early Universe

    CERN Document Server

    Green, Anne M

    2014-01-01

    Primordial Black Holes (PBHs) are, typically light, black holes which can form in the early Universe. There are a number of formation mechanisms, including the collapse of large density perturbations, cosmic string loops and bubble collisions. The number of PBHs formed is tightly constrained by the consequences of their evaporation and their lensing and dynamical effects. Therefore PBHs are a powerful probe of the physics of the early Universe, in particular models of inflation. They are also a potential cold dark matter candidate.

  20. A search for z <1.2 Ly-alpha Blobs using SWIFT

    Science.gov (United States)

    Ashcraft, Teresa; Hegel, P.; Jansen, R. A.; Rutkowski, M. J.; Windhorst, R. A.

    2014-01-01

    A recent major discovery has been that of “blobs” of Ly-α (LABs) emission at high (z > 1.7) redshift. These objects are distinguished by their relative lack of stellar continuum emission, large physical and angular sizes, and are found in regions of high galaxy density. The limited information available on LABs makes their nature unclear. Possibilities include cooling radiation from collapsing protogalactic clouds, cold gas stream accretion onto dark matter halos, superwinds from massive starbursts, and gas photoionized by obscured or transient AGN. As with any new class of object, more data and larger samples are needed to narrow down the range of possibilities. Below z ~ 1.7, Lyα detection require space-based observations. Keel et al. (2009) used deep GALEX grism observations of two fields centered on galaxy clusters at z = 0.8, in order to constrain the comoving space density of the LAB population at that redshift. No LABs were detected. Based on limited data, this result suggest a rapid decrease in the space density of LABs since z ~ 2. Using Swift’s unique ultraviolet imaging capability, we attempt to locate z test the theory that blob activity is regulated in part by cluster formation by searching for blobs in the vicinity of QSOs. Our search consisted of 130 observations with the Swift/UVOT instrument's UVW1 (corresponds to Ly-α at z ~ 1.1) and UVW2 (corresponds to Ly-α at 0.55) filters centered on QSOs at z ~0.55. To probe the hosts of our Ly-α Blob candidates, we obtained follow-up ground-based optical observations of 30 candidates using the VATT 4k CCD in the U, B, and V filters. We present SEDs for the most promising objects and a census of the contents of our UVOT fields.

  1. Hole transport in pure and doped hematite

    Science.gov (United States)

    Liao, Peilin; Carter, Emily A.

    2012-07-01

    Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

  2. Black Hole Dynamic Potentials

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... In the following paper, certain black hole dynamic potentials have been developed definitively on the lines of classical thermodynamics. These potentials have been refined in view of the small differences in the equations of the laws of black hole dynamics as given by Bekenstein and those of ...

  3. Black hole levitron

    NARCIS (Netherlands)

    Arsiwalla, X.D.; Verlinde, E.P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.’s multicenter

  4. Black holes matter

    DEFF Research Database (Denmark)

    Kragh, Helge Stjernholm

    2016-01-01

    Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015).......Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015)....

  5. Black hole Berry phase

    NARCIS (Netherlands)

    de Boer, J.; Papadodimas, K.; Verlinde, E.

    2009-01-01

    Supersymmetric black holes are characterized by a large number of degenerate ground states. We argue that these black holes, like other quantum mechanical systems with such a degeneracy, are subject to a phenomenon which is called the geometric or Berry’s phase: under adiabatic variations of the

  6. Nonlinear interactions between black holes and Proca fields

    CERN Document Server

    Zilhão, Miguel; Cardoso, Vitor

    2015-01-01

    Physics beyond the Standard Model is an important candidate for dark matter, and an interesting testing ground for strong-field gravity: the equivalence principle "forces" all forms of matter to fall in the same way, and it is therefore natural to look for imprints of these fields in regions with strong gravitational fields, such as compact stars or black holes. Here we study General Relativity minimally coupled to a massive vector field, and how black holes in this theory lose "hair". Our results indicate that black holes can sustain Proca field condensates for extremely long time-scales.

  7. Black holes an introduction

    CERN Document Server

    Raine, Derek

    2005-01-01

    This introduction to the fascinating subject of black holes fills a significant gap in the literature which exists between popular, non-mathematical expositions and advanced textbooks at the research level. It is designed for advanced undergraduates and first year postgraduates as a useful stepping-stone to the advanced literature. The book provides an accessible introduction to the exact solutions of Einstein’s vacuum field equations describing spherical and axisymmetric (rotating) black holes. The geometry and physical properties of these spacetimes are explored through the motion of particles and light. The use of different coordinate systems, maximal extensions and Penrose diagrams is explained. The association of the surface area of a black hole with its entropy is discussed and it is shown that with the introduction of quantum mechanics black holes cease to be black and can radiate. This result allows black holes to satisfy the laws of thermodynamics and thus be consistent with the rest of physics.

  8. Black Hole Simulation

    Science.gov (United States)

    1999-01-01

    This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. This simulation was conducted using supercomputers at Japan's National Institute for Fusion Science.

  9. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Abstract. Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical ...

  10. Quartz modification by Zn ion implantation and swift Xe ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Privezentsev, Vladimir [Institute of Physics and Technology, Russian Academy of Sciences, Moscow (Russian Federation); Kulikauskas, Vaclav [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University (Russian Federation); Didyk, Alexander; Skuratov, Vladimir [Joint Institute of Nuclear Research, Dubna (Russian Federation); Steinman, Edward; Tereshchenko, Alexey; Kolesnikov, Nikolay [Institute of Solid-State Physics, Russian Academy of Sciences, Chernogolovka (Russian Federation); Trifonov, Alexey; Sakharov, Oleg [National Research University ' ' MIET' ' , Zelenograd, Moscow (Russian Federation); Ksenich, Sergey [National University of Science and Technology ' ' MISiS' ' , Moscow (Russian Federation)

    2017-07-15

    The quartz slides were implanted by {sup 64}Zn{sup +} ions with dose of 5 x 10{sup 16}/cm{sup 2} and energy of 100 keV. After implantation, the amorphous metallic Zn nanoparticles with an average radius of 3.5 nm were created. The sample surface becomes nonuniform, its roughness is increased and its values rise up to 6 nm compared to virgin state, and the roughness maximum is at a value of about 0.8 nm. The surface is made up of valleys and hillocks which have a round shape with an average diameter about 200 nm. At the center of these hillocks are pores with a depth up to 6 nm and a diameter of about 20 nm. After implantation in UV-vis diapason, the optical transmission decreases while PL peak (apparently due to oxygen deficient centers) at wavelength of 400 nm increases. Then the samples were subjected to swift Xe ion irradiation with the fluences of 1 x 10{sup 12}-7.5 x 10{sup 14}/cm{sup 2} and energy of 167 MeV. After Xe irradiation, the sample surface roughness shat down to values of 0.5 nm and the roughness maximum is at a value of about 0.1 nm. Optical transmission in UV-vis diapason increases. The PL peak at wavelength of 400 nm is decreased while a PL peak at wavelength of 660 nm is raised. This peak is presumably due to non-bridging oxygen hole centers or/and NPs with structure Si(core)/SiO{sub 2}(shell). HRTEM image of Zn-implanted quartz subsurface layer. One can see the Zn amorphous nanoparticles, which confirms the electron diffraction pattern (insert). (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. The Thermodynamics of Black Holes

    National Research Council Canada - National Science Library

    Emparan, Roberto; Tinto, Massimo; Barbero G, J Fernando; Heusler, Markus; Rendall, Alan D; Adamo, Timothy M; Liebling, Steven L; Sasaki, Misao; Poisson, Eric; Wald, Robert M; Postnov, Konstantin A; Amendola, Luca; Shibata, Masaru; Tagoshi, Hideyuki; Reall, Harvey S; Kozameh, Carlos; Palenzuela, Carlos; Yungelson, Lev R; Villaseñor, Eduardo J. S; Appleby, Stephen; Taniguchi, Keisuke; Dhurandhar, Sanjeev V; Bacon, David; Newman, Ezra T; Baker, Tessa; Baldi, Marco; Bartolo, Nicola; Blanchard, Alain; Bonvin, Camille; Borgani, Stefano; Branchini, Enzo; Burrage, Clare; Camera, Stefano; Carbone, Carmelita; Casarini, Luciano; Cropper, Mark; de Rham, Claudia; Di Porto, Cinzia; Ealet, Anne; Ferreira, Pedro G; Finelli, Fabio; García-Bellido, Juan; Giannantonio, Tommaso; Guzzo, Luigi; Heavens, Alan; Heisenberg, Lavinia; Heymans, Catherine; Hoekstra, Henk; Hollenstein, Lukas; Holmes, Rory; Horst, Ole; Jahnke, Knud; Kitching, Thomas D; Koivisto, Tomi; Kunz, Martin; La Vacca, Giuseppe; March, Marisa; Majerotto, Elisabetta; Markovic, Katarina; Marsh, David; Marulli, Federico; Massey, Richard; Mellier, Yannick; Mota, David F; Nunes, Nelson J; Percival, Will; Pettorino, Valeria; Porciani, Cristiano; Quercellini, Claudia; Read, Justin; Rinaldi, Massimiliano; Sapone, Domenico; Scaramella, Roberto; Skordis, Constantinos; Simpson, Fergus; Taylor, Andy; Thomas, Shaun; Trotta, Roberto; Verde, Licia; Vernizzi, Filippo; Vollmer, Adrian; Wang, Yun; Weller, Jochen; Zlosnik, Tom

    ...We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds...

  12. Hole-ness of point clouds

    Science.gov (United States)

    Gronz, Oliver; Seeger, Manuel; Klaes, Björn; Casper, Markus C.; Ries, Johannes B.

    2015-04-01

    Accurate and dense 3D models of soil surfaces can be used in various ways: They can be used as initial shapes for erosion models. They can be used as benchmark shapes for erosion model outputs. They can be used to derive metrics, such as random roughness... One easy and low-cost method to produce these models is structure from motion (SfM). Using this method, two questions arise: Does the soil moisture, which changes the colour, albedo and reflectivity of the soil, influence the model quality? How can the model quality be evaluated? To answer these questions, a suitable data set has been produced: soil has been placed on a tray and areas with different roughness structures have been formed. For different moisture states - dry, medium, saturated - and two different lighting conditions - direct and indirect - sets of high-resolution images at the same camera positions have been taken. From the six image sets, 3D point clouds have been produced using VisualSfM. The visual inspection of the 3D models showed that all models have different areas, where holes of different sizes occur. But it is obviously a subjective task to determine the model's quality by visual inspection. One typical approach to evaluate model quality objectively is to estimate the point density on a regular, two-dimensional grid: the number of 3D points in each grid cell projected on a plane is calculated. This works well for surfaces that do not show vertical structures. Along vertical structures, many points will be projected on the same grid cell and thus the point density rather depends on the shape of the surface but less on the quality of the model. Another approach has been applied by using the points resulting from Poisson Surface Reconstructions. One of this algorithm's properties is the filling of holes: new points are interpolated inside the holes. Using the original 3D point cloud and the interpolated Poisson point set, two analyses have been performed: For all Poisson points, the

  13. Dance of Two Monster Black Holes

    Science.gov (United States)

    Kohler, Susanna

    2016-03-01

    than two dozen ground-based optical telescopes and the Swift/XRT satellite to observe OJ 287 in this time frame. The outburst occurred right on schedule, peaking on 5 December 2015, and the results of the observing campaign are now presented in a study led by Mauri Valtonen (University of Turku).Optical photometry of OJ 287 from October to December 2015, showing the outburst that resulted from the secondary black hole crossing the disk. [Valtonen et al. 2016]Because the secondary black holes orbit is affected by the spin of the primary black hole, Valtonen and collaborators were able to use the timing of the outburst to measure the spin of OJ 287s primary black hole to remarkably high precision. They find that its Kerr parameter is 0.313 0.01 which means its spinning at about a third of the maximum rate allowed by general relativity.The outburst timing also confirmed several general-relativistic properties of the system, including its loss of energy to gravitational waves. Remarkably, the energy lost as the secondary black hole punches through the accretion disk is still ten thousand times smaller than the amount of energy it loses through gravitational waves!The observations from this outburst have provided important black-hole measurements and tests of general relativity which are especially relevant in this new era of gravitational wave detections. And we may be able to perform still more tests on the secondarys next pass through the disk, which should occur in 2019.BonusCheck out this awesome animation of the orbits in a system similar to OJ 287! The secondarys orbit precesses around the primary due to general-relativistic effects. The sound you hearis an audio representation of the increasing frequency as the two black holes inspiral. You can find more information about this animation here. [Steve Drasco Curt Cutler]CitationM. J. Valtonen et al 2016 ApJ 819 L37. doi:10.3847/2041-8205/819/2/L37

  14. Diets of swift foxes (Vulpes velox) in continuous and fragmented prairie in Northwestern Texas

    Science.gov (United States)

    Kamler, J.F.; Ballard, W.B.; Wallace, M.C.; Gipson, P.S.

    2007-01-01

    Distribution of the swift fox (Vulpes velox) has declined dramatically since the 1800s, and suggested causes of this decline are habitat fragmentation and transformation due to agricultural expansion. However, impacts of fragmentation and human-altered habitats on swift foxes still are not well understood. To better understand what effects these factors have on diets of swift foxes, scats were collected in northwestern Texas at two study sites, one of continuous native prairie and one representing fragmented native prairie interspersed with agricultural and fields in the Conservation Reserve Program. Leporids, a potential food source, were surveyed seasonally on both sites. Diets of swift foxes differed between sites; insects were consumed more on continuous prairie, whereas mammals, birds, and crops were consumed more on fragmented prairie. Size of populations of leporids were 2-3 times higher on fragmented prairie, and swift foxes responded by consuming more leporids on fragmented (11.1% frequency occurrence) than continuous (3.8%) prairie. Dietary diversity was greater on fragmented prairie during both years of the study. Differences in diets between sites suggested that the swift fox is an adaptable and opportunistic feeder, able to exploit a variety of food resources, probably in relation to availability of food. We suggest that compared to continuous native prairie, fragmented prairie can offer swift foxes a more diverse prey base, at least within the mosaic of native prairie, agricultural, and fields that are in the Conservation Reserve Program.

  15. Swift/BAT detects an outburst from UX Ari

    Science.gov (United States)

    Krimm, H. A.; Barthelmy, S. D.; Baumgartner, W.; Cummings, J.; Gehrels, N.; Lien, A. Y.; Markwardt, C. B.; Palmer, D.; Sakamoto, T.; Stamatikos, M.; Ukwatta, T.

    2014-02-01

    The RS Canum Venaticorum type variable star UX Ari is currently in outburst as detected in the Swift/BAT hard X-ray transient monitor in the 15-50 keV band. The current outburst began on 2014 February 14 (MJD 56702) when it had a count rate of 0.004 +/- 0.002 ct/s/cm^2 (~20 mCrab). It continued to brighten, reaching a rate of 0.013 +/- 0.003 ct/s/cm^2 (~60 mCrab) on 2014 February 17. It has since faded somewhat, with a rate of 0.005 +/- 0.002 ct/s/cm^2 (~20 mCrab) on 2014 February 19.

  16. Swift heavy ion modifications of astrophysical water ice

    Energy Technology Data Exchange (ETDEWEB)

    Dartois, E., E-mail: emmanuel.dartois@ias.u-psud.fr [CNRS-INSU, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, bât. 121, 91405 Orsay (France); Augé, B. [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CEA, CNRS, ENSICAEN, Université de Caen-Basse Normandie), UMR 6252, CIMAP – CIRIL – Ganil, Boulevard Henri Becquerel, BP 5133, 14070 Caen Cedex 05 (France); CNRS-INSU, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, bât. 121, 91405 Orsay (France); Rothard, H.; Boduch, P. [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CEA, CNRS, ENSICAEN, Université de Caen-Basse Normandie), UMR 6252, CIMAP – CIRIL – Ganil, Boulevard Henri Becquerel, BP 5133, 14070 Caen Cedex 05 (France); Brunetto, R. [CNRS-INSU, Institut d’Astrophysique Spatiale, UMR 8617, 91405 Orsay (France); Université Paris Sud, Institut d’Astrophysique Spatiale, UMR 8617, bât. 121, 91405 Orsay (France); and others

    2015-12-15

    In the relatively shielded environments provided by interstellar dense clouds in our Galaxy, infrared astronomical observations have early revealed the presence of low temperature (10–100 K) ice mantles covering tiny grain “cores” composed of more refractory material. These ices are of specific interest because they constitute an interface between a solid phase under complex evolution triggered by energetic processes and surface reactions, with a rich chemistry taking place in the gas phase. The interstellar ice mantles present in these environments are immersed, in addition to other existing radiations fields, in a flux of cosmic ray particles that can produce new species via radiolysis processes, but first affects their structure, which may change and also induces desorption of molecules and radicals from these grains. Theses cosmic rays are simulated by swift ions in the laboratory for a better understanding of astrophysical processes.

  17. A complete sample of long bright Swift gamma ray bursts.

    Science.gov (United States)

    Tagliaferri, Gianpiero; Salvaterra, Ruben; Campana, Sergio; Covino, Stefano; D'Avanzo, Paolo; Fugazza, Dino; Ghirlanda, Giancarlo; Ghisellini, Gabriele; Melandri, Andrea; Nava, Lara; Sbarufatti, Boris; Vergani, Susanna

    2013-06-13

    Complete samples are the basis of any population study. To this end, we selected a complete subsample of Swift long bright gamma ray bursts (GRBs). The sample, made up of 58 bursts, was selected by considering bursts with favourable observing conditions for ground-based follow-up observations and with the 15-150 keV 1 s peak flux above a flux threshold of 2.6 photons cm(-2) s(-1). This sample has a redshift completeness level higher than 90 per cent. Using this complete sample, we investigate the properties of long GRBs and their evolution with cosmic time, focusing in particular on the GRB luminosity function, the prompt emission spectral-energy correlations and the nature of dark bursts.

  18. Merging and Clustering of the Swift BAT AGN Sample

    Science.gov (United States)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa

    2010-06-01

    We discuss the merger rate, close galaxy environment, and clustering on scales up to an Mpc of the Swift BAT hard X-ray sample of nearby (zincidence of galaxies with signs of disruption compared to a matched control sample (18% versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a larger fraction with companions compared to normal galaxies and optical emission line selected AGNs at scales up to 250 kpc. We hypothesize that these merging AGNs may not be identified using optical emission line diagnostics because of optical extinction and dilution by star formation. In support of this hypothesis, in merging systems we find a higher hard X-ray to [O III] flux ratio, as well as emission line diagnostics characteristic of composite or star-forming galaxies, and a larger IRAS 60 μm to stellar mass ratio.

  19. FERMI LAT STACKING ANALYSIS OF SWIFT LOCALIZED GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Axelsson, M. [Department of Physics, KTH Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bhat, P. N. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, 70126 Bari (Italy); Bonino, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Bottacini, E.; Caliandro, G. A.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, Montpellier (France); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France); Anderson, B., E-mail: jchiang@slac.stanford.edu; and others

    2016-05-10

    We perform a comprehensive stacking analysis of data collected by the Fermi Large Area Telescope (LAT) of γ -ray bursts (GRBs) localized by the Swift spacecraft, which were not detected by the LAT but which fell within the instrument’s field of view at the time of trigger. We examine a total of 79 GRBs by comparing the observed counts over a range of time intervals to that expected from designated background orbits, as well as by using a joint likelihood technique to model the expected distribution of stacked counts. We find strong evidence for subthreshold emission at MeV to GeV energies using both techniques. This observed excess is detected during intervals that include and exceed the durations typically characterizing the prompt emission observed at keV energies and lasts at least 2700 s after the co-aligned burst trigger. By utilizing a novel cumulative likelihood analysis, we find that although a burst’s prompt γ -ray and afterglow X-ray flux both correlate with the strength of the subthreshold emission, the X-ray afterglow flux measured by Swift ’ s X-ray Telescope at 11 hr post trigger correlates far more significantly. Overall, the extended nature of the subthreshold emission and its connection to the burst’s afterglow brightness lend further support to the external forward shock origin of the late-time emission detected by the LAT. These results suggest that the extended high-energy emission observed by the LAT may be a relatively common feature but remains undetected in a majority of bursts owing to instrumental threshold effects.

  20. Antarctic Ozone Hole, 2000

    Science.gov (United States)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  1. Simultaneous NuSTAR and XMM-Newton 0.5-80 KeV Spectroscopy of the Narrow-Line Seyfert 1 Galaxy SWIFT J2127.4+5654

    Science.gov (United States)

    Marinucci, A.; Matt, G.; Kara, E.; Miniutti, G.; Elvis, M.; Arevalo, P.; Ballantyne, D. R.; Balokovic, M.; Bauer, F.; Brenneman, L.; hide

    2014-01-01

    We present a broad-band spectral analysis of the joint XMM-Newton and Nuclear Spectroscopic Telescope Array observational campaign of the narrow-line Seyfert 1 SWIFT J2127.4+5654, consisting of 300 kiloseconds performed during three XMM-Newton orbits. We detect a relativistic broadened iron K-alpha line originating from the innermost regions of the accretion disc surrounding the central black hole, from which we infer an intermediate spin of a = 0.58 (sup +0.11) (sub -0.17). The intrinsic spectrum is steep (gamma = 2.08 plus or minus 0.01) as commonly found in narrow-line Seyfert 1 galaxies, while the cutoff energy (E (sub c) = 108 (sup +11) (sub -10) kiloelectronvolts) falls within the range observed in broad-line Seyfert 1 galaxies. We measure a low-frequency lag that increases steadily with energy, while at high frequencies, there is a clear lag following the shape of the broad Fe K emission line. Interestingly, the observed Fe K lag in SWIFT J2127.4+5654 is not as broad as in other sources that have maximally spinning black holes. The lag amplitude suggests a continuum-to-reprocessor distance of about 10-20 radius of gyration. These timing results independently support an intermediate black hole spin and a compact corona.

  2. Scalarized hairy black holes

    Energy Technology Data Exchange (ETDEWEB)

    Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kunz, Jutta [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Yazadjiev, Stoytcho [Department of Theoretical Physics, Faculty of Physics, Sofia University, Sofia 1164 (Bulgaria)

    2015-05-11

    In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  3. Scalarized Hairy Black Holes

    CERN Document Server

    Kleihaus, Burkhard; Yazadjiev, Stoytcho

    2015-01-01

    In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  4. Black hole uncertainties

    CERN Document Server

    Danielsson, U H

    1993-01-01

    In this work the quantum theory of two dimensional dilaton black holes is studied using the Wheeler De Witt equation. The solutions correspond to wave functions of the black hole. It is found that for an observer inside the horizon, there are uncertainty relations for the black hole mass and a parameter in the metric determining the Hawking flux. Only for a particular value of this parameter, can both be known with arbitrary accuracy. In the generic case there is instead a relation which is very similar to the so called string uncertainty relation.

  5. Black holes new horizons

    CERN Document Server

    Hayward, Sean Alan

    2013-01-01

    Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h

  6. Scalarized hairy black holes

    Directory of Open Access Journals (Sweden)

    Burkhard Kleihaus

    2015-05-01

    Full Text Available In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  7. Fermi GBM detects pulsations from Swift J0243.6+6124

    Science.gov (United States)

    Jenke, P.; Wilson-Hodge, C. A.

    2017-10-01

    On October 1, 2017, blind searches of Fermi GBM data detected strong pulsations from an unknown source with a pulse period of 4.927 seconds. Upon the Swift discovery of the new 9.86 second accreting NS, Swift J0243.6+6124 (ATeL #10809), the GBM pulsar project performed a dedicated search for pulsations around the pulse period of 9.86 seconds from the direction of Swift J0243.6+6124 starting September 01 through October 2, 2017.

  8. Candidate optical counterparts of MAXI J1543-564

    NARCIS (Netherlands)

    Russell, D.M.; Lewis, F.; Roche, P.; Altamirano, D.

    2011-01-01

    We report on optical observations of the field of the black hole candidate X-ray binary MAXI J1543-564 (ATel #3330, #3331, #3334, #3336, #3341, #3355) with the 2-m Faulkes Telescope South (located at Siding Spring, Australia). Three images were acquired in SDSS i'-band on 2011 May 11th, 14th and

  9. Black Hole Shadows of Charged Spinning Black Holes

    OpenAIRE

    Takahashi, Rohta

    2005-01-01

    We propose a method for measuring the black hole charge by imaging a black hole shadow in a galactic center by future interferometers. Even when the black hole is uncharged, it is possible to confirm the charge neutrality by this method. We first derive the analytic formulae of the black hole shadow in an optically thin medium around a charged spinning black hole, and then investigate how contours of the black hole shadow depend on the spin and the charge of the black hole for several inclina...

  10. Black holes with halos

    Science.gov (United States)

    Monten, Ruben; Toldo, Chiara

    2018-02-01

    We present new AdS4 black hole solutions in N =2 gauged supergravity coupled to vector and hypermultiplets. We focus on a particular consistent truncation of M-theory on the homogeneous Sasaki–Einstein seven-manifold M 111, characterized by the presence of one Betti vector multiplet. We numerically construct static and spherically symmetric black holes with electric and magnetic charges, corresponding to M2 and M5 branes wrapping non-contractible cycles of the internal manifold. The novel feature characterizing these nonzero temperature configurations is the presence of a massive vector field halo. Moreover, we verify the first law of black hole mechanics and we study the thermodynamics in the canonical ensemble. We analyze the behavior of the massive vector field condensate across the small-large black hole phase transition and we interpret the process in the dual field theory.

  11. Blue Holes & Hurricanes

    National Research Council Canada - National Science Library

    David Levin

    2017-01-01

    A blue hole in the ocean is a striking sight. Fly over remote areas of the Caribbean Sea and you'll see shallow turquoise water stretching for miles, interrupted only by occasional sand bars and coral reefs...

  12. Illuminating black holes

    Science.gov (United States)

    Barr, Ian A.; Bull, Anne; O'Brien, Eileen; Drillsma-Milgrom, Katy A.; Milgrom, Lionel R.

    2016-07-01

    Two-dimensional shadows formed by illuminating vortices are shown to be visually analogous to the gravitational action of black holes on light and surrounding matter. They could be useful teaching aids demonstrating some of the consequences of general relativity.

  13. Nonsingular black hole

    Science.gov (United States)

    Chamseddine, Ali H.; Mukhanov, Viatcheslav

    2017-03-01

    We consider the Schwarzschild black hole and show how, in a theory with limiting curvature, the physical singularity "inside it" is removed. The resulting spacetime is geodesically complete. The internal structure of this nonsingular black hole is analogous to Russian nesting dolls. Namely, after falling into the black hole of radius rg, an observer, instead of being destroyed at the singularity, gets for a short time into the region with limiting curvature. After that he re-emerges in the near horizon region of a spacetime described by the Schwarzschild metric of a gravitational radius proportional to rg^{1/3}. In the next cycle, after passing the limiting curvature, the observer finds himself within a black hole of even smaller radius proportional to rg^{1/9}, and so on. Finally after a few cycles he will end up in the spacetime where he remains forever at limiting curvature.

  14. Black hole quantum spectrum

    National Research Council Canada - National Science Library

    Corda, Christian

    2013-01-01

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re...

  15. Holographic black hole chemistry

    National Research Council Canada - National Science Library

    Karch, Andreas; Robinson, Brandon

    2015-01-01

    Thermodynamic quantities associated with black holes in Anti-de Sitter space obey an interesting identity when the cosmological constant is included as one of the dynamical variables, the generalized Smarr relation...

  16. Accurate Black Hole Spin Measurements using ABC

    Science.gov (United States)

    Connolly, Andrew

    time. In particular, a class of methods col- lectively called Approximate Bayesian Computation (ABC) is capable of exploiting the fact that it is possible to simulate instrumental effects to a high degree of accuracy in order to build reliable statistical models incorporating pile-up and related effects. With the loss of the Hitomi spacecraft, it is more important than ever to make full use of the data we collect with current instruments. We propose an ambitious program to estimate the spins of 13 black holes in X-ray binaries using observations with XMMNewton s EPIC MOS and pn, Suzaku s XIS and Chandra s ACIS and HETG instruments. We will build a general framework for dealing with pile-up in spectral modeling using ABC and refine current instrumental simulators for inclusion in this framework. Coupled with state-of-the- art sampling methods, this will allow us to take advantage of dozens of observations in the archives of all three instruments. We will be able to estimate spins to much bet- ter accuracy than ever before and test current models for black hole formation as well as jet launching mechanisms. The program will deliver a considerable legacy, because the statistical and methodological framework will be general. Application to other instruments suffering from photon pile-up, e.g. Swift/XRT, Fermi/GBM, ASCA/SIS, and GALEX, will only require is a model capable of simulating the relevant instrumental effects. This will enable other science cases beyond that proposed here which rely on precise spectral measurements or cases where pile-up cannot be avoided, e.g. high-precision radius measurements in neutron stars, understanding X-ray dust scattering, and stellar evolution studies of globular clusters.

  17. Charged Galileon black holes

    Energy Technology Data Exchange (ETDEWEB)

    Babichev, Eugeny; Charmousis, Christos [Laboratoire de Physique Théorique (LPT), Univ. Paris-Sud, CNRS UMR 8627, F-91405 Orsay (France); Hassaine, Mokhtar, E-mail: eugeny.babichev@th.u-psud.fr, E-mail: christos.charmousis@th.u-psud.fr, E-mail: hassaine@inst-mat.utalca.cl [Instituto de Matemática y Física, Universidad de Talca, Casilla 747, Talca (Chile)

    2015-05-01

    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.

  18. A catalogue of optical to X-ray spectral energy distributions of z ≈ 2 quasars observed with Swift - I. First results

    Science.gov (United States)

    Lawther, D.; Vestergaard, M.; Raimundo, S.; Grupe, D.

    2017-06-01

    We present the Swift optical to X-ray spectral energy distributions (SEDs) of 44 quasars at redshifts z ≈ 2 observed by Swift, part of a larger program to establish and characterize the optical through X-ray SEDs of moderate-redshift quasars. Here, we outline our analysis approach and present preliminary analysis and results for the first third of the full quasar sample. Not all quasars in the sample are detected in X-rays; all of the X-ray-detected objects so far are radio loud. As expected for radio-loud objects, they are X-ray bright relative to radio-quiet quasars of comparable optical luminosities, with an average αox =1.39 ± 0.03 (where αox is the power-law slope connecting the monochromatic flux at 2500 Å and at 2 keV), and display hard X-ray spectra. We find integrated 3000 Å-25 keV accretion luminosities of between 0.7 × 1046 erg s-1 and 5.2 × 1047 erg s-1. Based on single-epoch spectroscopic virial black hole mass estimates, we find that these quasars are accreting at substantial Eddington fractions, 0.1 ≲ L/LEdd ≲ 1.

  19. Magnetorotatioal Collapse of Supermassive Stars: Black Hole Formation and Jets

    Science.gov (United States)

    Sun, Lunan; Paschalidis, Vasileios; Ruiz, Milton; Shapiro, Stuart

    2017-01-01

    We perform magnetohydrodynamic simulations in full general relativity of the collapse of radially unstable, uniformly rotating, massive stars to black holes. The stars spin at the mass-shedding limit, account for magnetic fields and obey a Γ = 4/3 EOS. The calculations lift the restriction of axisymmetry imposed in previous simulations. Our simulations model the direct collapse of supermassive stars to supermassive BHs (>=104M⊙) at high cosmological redshifts, which may explain the appearance of supermassive BHs and quasars by z 7. They also crudely model the collapse of massive Pop III stars to massive BHs, which could power some of the long gamma-ray bursts observed by FERMI and SWIFT at z 6-8. We analyze the properties of the electromagnetic and gravitational wave signatures of these events and discuss the detectability of such multimessenger sources.

  20. Background Studies for the Black Hole Finder Probe EXIST

    Science.gov (United States)

    Garson, Alfred, III; Sturner, S.; Skinner, G.; Krawczynski, H.; Hong, J.; Grindlay, J.

    2009-12-01

    The Energetic X-ray Imaging Survey Telescope (EXIST) will provide a wide field of view survey of the hard X-ray sky in order to detect and locate black holes of many different mass scales and redshifts. EXIST's High Energy Telescope (HET) will use 5mm-thick CZT detectors and be sensitive from 5 -600 keV. As fluctuations in background rates will largely determine the sensitivity of EXIST's CZT detectors, predicting and understanding the background rates from multiple components found in low Earth orbit are crucial to the feasibility of science objectives and mission design. We report on new Monte Carlo simulations of the background environment expected for EXIST's orbit. We validate our results by comparing simulated and observed background rates for Swift's Burst Alert Telescope. This is work is supported by NASA under contract NNX07AH37G.

  1. The Thermodynamics of Black Holes

    Directory of Open Access Journals (Sweden)

    Wald Robert M.

    2001-01-01

    Full Text Available We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.

  2. THE SWIFT X-RAY TELESCOPE CLUSTER SURVEY. III. CLUSTER CATALOG FROM 2005-2012 ARCHIVAL DATA

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Teng; Wang, Jun-Xian [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, 230026 Hefei, Anhui (China); Tozzi, Paolo; Tundo, Elena [INAF, Osservatorio Astrofisico di Firenze, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Moretti, Alberto [INAF, Osservatorio Astronomico di Brera, Via Brera 28, I-20121 Milano (Italy); Rosati, Piero [Università degli Studi di Ferrara, Dipartimento di Fisica e Scienze della Terra, Via Saragat 1, I-44121 Ferrara (Italy); Tagliaferri, Gianpiero; Campana, Sergio [INAF, Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate (Italy); Giavalisco, Mauro, E-mail: liuteng@ustc.edu.cn [Department of Astronomy, University of Massachusetts, LGRT-B 619E, 710 North Pleasant Street, Amherst, MA (United States)

    2015-02-01

    We present the Swift X-ray Cluster Survey (SWXCS) catalog obtained using archival data from the X-ray telescope (XRT) on board the Swift satellite acquired from 2005 February to 2012 November, extending the first release of the SWXCS. The catalog provides positions, soft fluxes, and, when possible, optical counterparts for a flux-limited sample of X-ray group and cluster candidates. We consider the fields with Galactic latitude |b| > 20° to avoid high H I column densities. We discard all of the observations targeted at groups or clusters of galaxies, as well as particular extragalactic fields not suitable to search for faint extended sources. We finally select ∼3000 useful fields covering a total solid angle of ∼400 deg{sup 2}. We identify extended source candidates in the soft-band (0.5-2 keV) images of these fields using the software EXSdetect, which is specifically calibrated for the XRT data. Extensive simulations are used to evaluate contamination and completeness as a function of the source signal, allowing us to minimize the number of spurious detections and to robustly assess the selection function. Our catalog includes 263 candidate galaxy clusters and groups down to a flux limit of 7 × 10{sup –15} erg cm{sup –2} s{sup –1} in the soft band, and the logN-logS is in very good agreement with previous deep X-ray surveys. The final list of sources is cross-correlated with published optical, X-ray, and Sunyaev-Zeldovich catalogs of clusters. We find that 137 sources have been previously identified as clusters in the literature in independent surveys, while 126 are new detections. Currently, we have collected redshift information for 158 sources (60% of the entire sample). Once the optical follow-up and the X-ray spectral analysis of the sources are complete, the SWXCS will provide a large and well-defined catalog of groups and clusters of galaxies to perform statistical studies of cluster properties and tests of cosmological models.

  3. SWIFT-HPX - High Data Rate Ka-band Commications for Small Satellites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leveraging TUI's SWIFT software defined radio (SDR) architecture, we propose to develop a 100 Mbps downlink and intersatellite crosslink capability with ranging and...

  4. The Swift satellite lives up to its name, revealing cosmic explosions as they happen

    National Research Council Canada - National Science Library

    Rhaana L.C Starling

    2008-01-01

    ... populations, one of which may originate in the deaths of massive stars. The launch of the Swift satellite in 2004 brought a flurry of new discoveries, advancing our understanding of these sources and the galaxies that host...

  5. The effect of He and swift heavy ions on nanocrystalline zirconium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Janse van Vuuren, A., E-mail: arnojvv@gmail.com [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for HRTEM, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Skuratov, V.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Uglov, V.V. [Belarusian State University, Minsk (Belarus); Petrovich, S. [VINCA Institute of Nuclear Sciences, Belgrade University, Belgrade (Serbia)

    2014-05-01

    Recent studies have shown that swift heavy ion irradiation may significantly modulate hydrogen and helium behaviour in some materials. This phenomenon is of considerable practical interest for ceramics in general and also for candidate materials for use as inert matrix fuel hosts. These materials will accumulate helium via (n, α) reactions and will also be subjected to irradiation by fission fragments. Cross-sectional transmission electron microscopy and scanning electron microscopy was used to study nanocrystalline ZrN irradiated with 30 keV He to fluences between 10{sup 16} and 5 × 10{sup 16} cm{sup −2}, 167 MeV Xe to fluences between 5 × 10{sup 13} and 10{sup 14} cm{sup −2} and also 695 MeV Bi to a fluence of 1.5 × 10{sup 13} cm{sup −2}. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C and were analysed using SEM, XTEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. SEM and XTEM analysis of He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.

  6. Swift follow-up of the newly discovered burster millisecond pulsar IGR J17511-3057

    NARCIS (Netherlands)

    Bozzo, E.; Ferrigno, C.; Kuulkers, E.; Falanga, M.; Chenevez, J.; Brandt, S.; Beckmann, V.; Bird, A.; Domingo, A.; Ebisawa, K.; Jonker, P.; Kretschmar, P.; Markwardt, C.; Oosterbroek, T.; Paizis, A.; Risquez, D.; Sanchez-Fernandez, C.; Shaw, S.; Wijnands, R.

    2009-01-01

    Following the discovery of the new hard X-ray transient IGR J17511-3057 by INTEGRAL (Atel #2196) and its classification as a millisecond pulsar by RXTE (Atel #2197), a Swift ToO was performed. Swift/XRT observed IGR J17511-3057 on 2009-09-13 at 19:53:31 for a total exposure time of 4 ks. The first

  7. Swift follow-up of the newly discovered burster millisecond pulsar IGR J17511-3057

    DEFF Research Database (Denmark)

    Bozzo, E.; Ferrigno, C.; Kuulkers, E.

    2009-01-01

    Following the discovery of the new hard X-ray transient IGR J17511-3057 by INTEGRAL (Atel #2196) and its classification as a millisecond pulsar by RXTE (Atel #2197), a Swift ToO was performed. Swift/XRT observed IGR J17511-3057 on 2009-09-13 at 19:53:31 for a total exposure time of 4 ks. The first...

  8. PRIMERJAVA PROGRAMSKIH JEZIKOV SWIFT IN OBJECTIVE-C NA PRIMERU APLIKACIJE HOKEJ DOGODKI

    OpenAIRE

    Svržnjak, Matej

    2016-01-01

    Cilj diplomske naloge je spoznati nova programska jezika Swift in Objective-C, ter ju primerjati pri razvijanju mobilne aplikacije za iOS. Izdelava bo v razvojnem okolju XCode, v katerem je omogočena uporaba obeh programskih jezikov. V uvodnem delu diplomskega dela je na kratko prikazana zgodovina operacijskega sistema iOS, platforma za distribucijo mobilnih aplikacij App Store, razvojno okolje Xcode ter programska jezika Swift in Objective-C. Sledi predstavitev izdelane aplikacije, funkciona...

  9. The Simpsons: Public Choice in the Tradition of Swift and Orwell

    Science.gov (United States)

    Considine, John

    2006-01-01

    The author disagrees with Homer Simpson who claims that "...cartoons don't have any deep meaning. They're just stupid drawings that give you a cheap laugh." He argues that The Simpsons have a deep meaning in the same way as the works of Jonathan Swift and George Orwell. The message in The Simpsons, Swift, and Orwell is that those in charge do not…

  10. SWIFT: Semi-empirical and numerically efficient stratospheric ozone chemistry for global climate models

    OpenAIRE

    Kreyling, Daniel; Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

    2015-01-01

    The SWIFT model is a fast yet accurate chemistry scheme for calculating the chemistry of stratospheric ozone. It is mainly intended for use in Global Climate Models (GCMs), Chemistry Climate Models (CCMs) and Earth System Models (ESMs). For computing time reasons these models often do not employ full stratospheric chem- istry modules, but use prescribed ozone instead. This can lead to insufficient representation between stratosphere and troposphere. The SWIFT stratospheric ozone chem...

  11. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

  12. Habitat selection by female swift foxes (Vulpes velox) during the pup-rearing season

    Science.gov (United States)

    Sasmal, Indrani; Jenks, Jonathan A.; Grovenburg, Troy W.; Datta, Shubham; Schroeder, Greg M.; Klaver, Robert W.; Honness, Kevin M.

    2011-01-01

    The swift fox (Vulpes velox) was historically distributed in western South Dakota including the region surrounding Badlands National Park (BNP). The species declined during the mid-1800s, largely due to habitat loss and poisoning targeted at wolves (Canis lupis) and coyotes (C. latrans). Only a small population of swift foxes near Ardmore, South Dakota persisted. In 2003, an introduction program was initiated at BNP with swift foxes translocated from Colorado and Wyoming. We report on habitat use by female swift foxes during the pup-rearing season (May–July) in 2009. Analyses of location data from 13 radiomarked female foxes indicated disproportional use (P Ŷ = 1.01), sparse vegetation (Ŷ = 1.43) and prairie dog towns (Ŷ = 1.18) in proportion to their availability, whereas they were less likely to use woodland (Ŷ = 0.00), shrubland (Ŷ = 0.14), pasture/agricultural-land (Ŷ = 0.25) and development (Ŷ = 0.16) relative to availability. Swift foxes typically are located in habitats that provide greater visibility, such as shortgrass prairie and areas with sparse vegetation; which allow detection of approaching coyotes (e.g., primary predator of swift foxes).

  13. Multistate observations of the Galactic black hole XTE J1752-223: evidence for an intermediate black hole spin

    NARCIS (Netherlands)

    Reis, R.C.; Miller, J.M.; Fabian, A.C.; Cackett, E.M.; Maitra, D.; Reynolds, C.S.; Rupen, M.; Steeghs, D.T.H.; Wijnands, R.

    2011-01-01

    The Galactic black hole candidate XTE J1752−223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ‘intermediate’ and ‘low-hard’ states, respectively. The presence of a strong, relativistic

  14. Merging Black Holes

    Science.gov (United States)

    Centrella, John

    2009-01-01

    The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.

  15. Dark Spinors Hawking Radiation in String Theory Black Holes

    Directory of Open Access Journals (Sweden)

    R. T. Cavalcanti

    2016-01-01

    Full Text Available The Hawking radiation spectrum of Kerr-Sen axion-dilaton black holes is derived, in the context of dark spinors tunnelling across the horizon. Since a black hole has a well defined temperature, it should radiate in principle all the standard model particles, similar to a black body at that temperature. We investigate the tunnelling of mass dimension one spin-1/2 dark fermions, which are beyond the standard model and are prime candidates to the dark matter. Their interactions with the standard model matter and gauge fields are suppressed by at least one power of unification scale, being restricted just to the Higgs field and to the graviton likewise. The tunnelling method for the emission and absorption of mass dimension one particles across the event horizon of Kerr-Sen axion-dilaton black holes is shown here to provide further evidence for the universality of black hole radiation, further encompassing particles beyond the standard model.

  16. Irradiation effects of swift heavy ions in matter

    Energy Technology Data Exchange (ETDEWEB)

    Osmani, Orkhan

    2011-12-22

    In the this thesis irradiation effects of swift heavy ions in matter are studied. The focus lies on the projectiles charge exchange and energy loss processes. A commonly used computer code which employs rate equations is the so called ETACHA code. This computer code is capable to also calculate the required input cross-sections. Within this thesis a new model to compute the charge state of swift heavy ions is explored. This model, the so called matrix method, takes the form of a simple algebraic expression, which also requires cross-sections as input. In the present implementation of the matrix method, cross-sections are taken from the ETACHA code, while excitation and deexcitation processes are neglected. Charge fractions for selected ion/target combinations, computed by the ETACHA code and the matrix method are compared. It is shown, that for sufficient large ion energies, both methods agree very well with each other. However, for lower energies pronounced differences are observed. These differences are believed to stem from the fact, that no excited states as well as the decay of theses excited states are included in the present implementation of the matrix method. Both methods are then compared with experimental measurements, where significant deviations are observed for both methods. While the predicted equilibrium charge state by both methods is in good agreement with the experiments, the matrix method predicts a much too large equilibrium thickness compared to both the ETACHA calculation as well as the experiment. Again, these deviations are believed to stem from the fact, that excitation and the decay of excited states are not included in the matrix method. A possible way to include decay processes into the matrix method is presented, while the accuracy of the applied capture cross-sections is tested by comparison with scaling rules. Swift heavy ions penetrating a dielectric are known to induced structural modifications both on the surface and in the bulk

  17. Model of wet chemical etching of swift heavy ions tracks

    Science.gov (United States)

    Gorbunov, S. A.; Malakhov, A. I.; Rymzhanov, R. A.; Volkov, A. E.

    2017-10-01

    A model of wet chemical etching of tracks of swift heavy ions (SHI) decelerated in solids in the electronic stopping regime is presented. This model takes into account both possible etching modes: etching controlled by diffusion of etchant molecules to the etching front, and etching controlled by the rate of a reaction of an etchant with a material. Olivine ((Mg0.88Fe0.12)2SiO4) crystals were chosen as a system for modeling. Two mechanisms of chemical activation of olivine around the SHI trajectory are considered. The first mechanism is activation stimulated by structural transformations in a nanometric track core, while the second one results from neutralization of metallic atoms by generated electrons spreading over micrometric distances. Monte-Carlo simulations (TREKIS code) form the basis for the description of excitations of the electronic subsystem and the lattice of olivine in an SHI track at times up to 100 fs after the projectile passage. Molecular dynamics supplies the initial conditions for modeling of lattice relaxation for longer times. These simulations enable us to estimate the effects of the chemical activation of olivine governed by both mechanisms. The developed model was applied to describe chemical activation and the etching kinetics of tracks of Au 2.1 GeV ions in olivine. The estimated lengthwise etching rate (38 µm · h-1) is in reasonable agreement with that detected in the experiments (24 µm · h-1).

  18. Black hole gravitohydromagnetics

    CERN Document Server

    Punsly, Brian

    2008-01-01

    Black hole gravitohydromagnetics (GHM) is developed from the rudiments to the frontiers of research in this book. GHM describes plasma interactions that combine the effects of gravity and a strong magnetic field, in the vicinity (ergosphere) of a rapidly rotating black hole. This topic was created in response to the astrophysical quest to understand the central engines of radio loud extragalactic radio sources. The theory describes a "torsional tug of war" between rotating ergospheric plasma and the distant asymptotic plasma that extracts the rotational inertia of the black hole. The recoil from the struggle between electromagnetic and gravitational forces near the event horizon is manifested as a powerful pair of magnetized particle beams (jets) that are ejected at nearly the speed of light. These bipolar jets feed large-scale magnetized plasmoids on scales as large as millions of light years (the radio lobes of extragalactic radio sources). This interaction can initiate jets that transport energy fluxes exc...

  19. Merging Black Holes

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics

  20. Black-hole astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Bender, P. [Univ. of Colorado, Boulder, CO (United States); Bloom, E. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Cominsky, L. [Sonoma State Univ., Rohnert Park, CA (United States). Dept. of Physics and Astronomy] [and others

    1995-07-01

    Black-hole astrophysics is not just the investigation of yet another, even if extremely remarkable type of celestial body, but a test of the correctness of the understanding of the very properties of space and time in very strong gravitational fields. Physicists` excitement at this new prospect for testing theories of fundamental processes is matched by that of astronomers at the possibility to discover and study a new and dramatically different kind of astronomical object. Here the authors review the currently known ways that black holes can be identified by their effects on their neighborhood--since, of course, the hole itself does not yield any direct evidence of its existence or information about its properties. The two most important empirical considerations are determination of masses, or lower limits thereof, of unseen companions in binary star systems, and measurement of luminosity fluctuations on very short time scales.

  1. Ozone Hole Over Antarctica

    Science.gov (United States)

    2002-01-01

    These images from the Total Ozone Mapping Spectrometer (TOMS) show the progressive depletion of ozone over Antarctica from 1979 to 1999. This 'ozone hole' has extended to cover an area as large as 10.5 million square miles in September 1998. The previous record of 10.0 million square miles was set in 1996. The Antarctic ozone hole develops each year between late August and early October. Regions with higher levels of ozone are shown in red. NASA and NOAA instruments have been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone began to develop over Antarctica in the early 1980s. Ozone holes of substantial size and depth are likely to continue to form during the next few years, scientists hope to see a reduction in ozone loss as levels of ozone-destroying CFCs (chlorofluorocarbons) are gradually reduced. Credit: Images by Greg Shirah, NASA Goddard Space Flight Center Scientific Visualization Studio

  2. Turbulent black holes.

    Science.gov (United States)

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

  3. Braneless Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Rajaraman, Arvind

    2003-06-02

    It is known that the naive version of D-brane theory is inadequate to explain the black hole entropy in the limit in which the Schwarzschild radius becomes larger than all compactification radii. We present evidence that a more consistent description can be given in terms of strings with rescaled tensions. We show that the rescaling can be interpreted as a redshift of the tension of a fundamental string in the gravitational field of the black hole. An interesting connection is found between the string level number and the Rindler energy. Using this connection, we reproduce the entropies of Schwarzschild black holes in arbitrary dimensions in terms of the entropy of a single string at the Hagedorn temperature.

  4. Characterizing Black Hole Mergers

    Science.gov (United States)

    Baker, John; Boggs, William Darian; Kelly, Bernard

    2010-01-01

    Binary black hole mergers are a promising source of gravitational waves for interferometric gravitational wave detectors. Recent advances in numerical relativity have revealed the predictions of General Relativity for the strong burst of radiation generated in the final moments of binary coalescence. We explore features in the merger radiation which characterize the final moments of merger and ringdown. Interpreting the waveforms in terms of an rotating implicit radiation source allows a unified phenomenological description of the system from inspiral through ringdown. Common features in the waveforms allow quantitative description of the merger signal which may provide insights for observations large-mass black hole binaries.

  5. Magnonic Black Holes

    Science.gov (United States)

    Roldán-Molina, A.; Nunez, Alvaro S.; Duine, R. A.

    2017-02-01

    We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons—the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

  6. Superfluid Black Holes.

    Science.gov (United States)

    Hennigar, Robie A; Mann, Robert B; Tjoa, Erickson

    2017-01-13

    We present what we believe is the first example of a "λ-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid ^{4}He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically anti-de Sitter hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.

  7. Magnonic Black Holes.

    Science.gov (United States)

    Roldán-Molina, A; Nunez, Alvaro S; Duine, R A

    2017-02-10

    We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons-the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

  8. Are Black Holes Springy?

    CERN Document Server

    Good, Michael R R

    2014-01-01

    A $(3+1)$-dimensional asymptotically flat Kerr black hole angular speed $\\Omega_+$ can be used to define an effective spring constant, $k=m\\Omega_+^2$. Its maximum value is the Schwarzschild surface gravity, $k = \\kappa $, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\\pi T = \\kappa - k$. Hooke's law, in the extremal limit, provides the force $F = 1/4$, which is consistent with the conjecture of maximum force in general relativity.

  9. Renewed activity of the Galactic center transients Swift J174535.5-290135.6 and GRS 1741.9-2853 as observed with Swift/XRT

    NARCIS (Netherlands)

    Wijnands, R.; Klein-Wolt, M.; Kuulkers, E.; Shaw, S.; Chenevez, J.; Brandt, S.; Courvoisier, T.J.L.; Domingo, A.; Kretschmar, P.; Markwardt, C.; Mowlavi, N.; Paizis, A.; Risquez, D.; Sanchez-Fernandez, C.

    2007-01-01

    Following the detection of a new Galactic center transient in our new series of INTEGRAL Galactic bulge monitoring observations (ATEL #1005), we obtained a short pointing with the XRT aboard Swift to improve significantly on the source position of this transient. This observation was performed on

  10. Pokročilé programové konstrukce a programovací techniky jazyka Swift

    OpenAIRE

    Čislinský, Jan

    2017-01-01

    The thesis focuses on advanced programming constructs and techniques of the Swift programming language. At the beginning programming paradigms that are supported by the Swift design (object-oriented and functional) are introduced. Concepts of each paradigm are described and Swift is then evaluated by the level of support for these paradigms. Following programming constructs are described in-depth: working with variables, optional types, enumerated types, functions and closures. Creating of cu...

  11. Study of a Tidal Disruption Event Candidate

    Science.gov (United States)

    Hampel, J.; Reiprich, T.; Freyberg, M.; Greiner, J.; Komossa, S.

    2017-10-01

    During the close encounter of a star with a supermassive black hole, the star might get disrupted by the black hole's tidal forces (tidal disruption events, TDE). The accretion of the stellar material onto the black hole creates luminous emission at different wavelength, including X-rays. We will report the results of an investigation of a bright X-ray source in a set of five ROSAT PSPC observations. The light curve of this event shows an increase in brightness by a factor of nine within eight days, followed by a strong fading over the following 165 days. This observation seems inconsistent with common X-ray source variability, such as active galactic nuclei, and more in favor of a TDE. In order to investigate the possible TDE origin, optical and X-ray spectra have been analyzed. An expected absence of emission lines in the optical and a very soft X-ray spectrum are confirmed. Detailed comparisons with known TDEs show discrepancies in the light curves. Particularly, the increase in brightness happens over a shorter timescale than comparable events. The study of this TDE candidate might help to gain a better understanding of such events, especially for the expected TDE discoveries with the upcoming eROSITA all-sky survey.

  12. Exploiting the richest patch has a fitness pay-off for the migratory swift parrot.

    Science.gov (United States)

    Stojanovic, Dejan; Terauds, Aleks; Westgate, Martin J; Webb, Matthew H; Roshier, David A; Heinsohn, Robert

    2015-09-01

    1. Unlike philopatric migrants, the ecology of nomadic migrants is less well understood. This life-history strategy reflects responses to spatiotemporal variation in resource availability and the need to find resource rich patches to initiate breeding. The fitness consequences of movements between regions of patchily distributed resources can provide insight into ecology of all migrants and their responses to global change. 2. We link broad-scale data on spatiotemporal fluctuation in food availability to data on settlement patterns and fitness outcomes for a nomadic migrant, the endangered swift parrot Lathamus discolor. We test several predictions to determine whether facultative movements are adaptive for individual swift parrots in an environment where resources are patchily distributed over time and space. 3. Variation in the availability of swift parrot food resources across our study period was dramatic. As a consequence, swift parrots moved to breed wherever food was most abundant and did not resettle nesting regions in successive years when food availability declined. By moving, swift parrots exploited a variable food resource and reproduced successfully. 4. Exploiting the richest patches allowed swift parrots to maintain stable fitness outcomes between discrete breeding events at different locations. Unlike sedentary species that often produce few or lower quality offspring when food is scarce, nomadic migration buffered swift parrots against extreme environmental variation. 5. We provide the first detailed evidence that facultative movements and nomadic migration are adaptive for individuals in unpredictable environments. Our data support the widely held assumption that nomadic migration allows animals to escape resource limitation. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

  13. Three new species of Dennyus Neumann, 1906 (Phthiraptera, Amblycera, Menoponidae parasitic on swifts (Aves, Apodiformes, Apodidae in Brazil

    Directory of Open Access Journals (Sweden)

    Michel P. Valim

    2013-01-01

    Full Text Available Descriptions and illustrations are given for three new species of the chewing louse genus Dennyus on Brazilian Swifts. They and their type hosts are: D. pichorimi ex Streptoprocne biscutata seridoensis (Biscutate Swift from the State of Rio Grande do Norte, D. pascoliae ex Streptoprocne zonaris zonaris (White-collared Swift from the state of Minas Gerais , D. malagonensis ex Cypseloides senex (Great Dusky Swift also from Minas Gerais. Thes e lice are the first published records of Dennyus species from Brazil. A key for the identificatio n of the Dennyus subgenera, and a table listing species of Dennyus recorded in other countrie s from hosts occurring in Brazil are given.

  14. Almost BPS black holes

    NARCIS (Netherlands)

    Goldstein, K.D.|info:eu-repo/dai/nl/314132376; Katmadas, S.

    2009-01-01

    We study non-BPS black hole solutions to ungauged supergravity with 8 supercharges coupled to vector multiplets in four and five dimensions. We identify a large class of five dimensional non-BPS solutions, which we call ``almost BPS'', that are supersymmetric on local patches and satisfy a first

  15. Nonsingular black hole

    Energy Technology Data Exchange (ETDEWEB)

    Chamseddine, Ali H. [American University of Beirut, Physics Department, Beirut (Lebanon); I.H.E.S., Bures-sur-Yvette (France); Mukhanov, Viatcheslav [Niels Bohr Institute, Niels Bohr International Academy, Copenhagen (Denmark); Ludwig-Maximilians University, Theoretical Physics, Munich (Germany); MPI for Physics, Munich (Germany)

    2017-03-15

    We consider the Schwarzschild black hole and show how, in a theory with limiting curvature, the physical singularity ''inside it'' is removed. The resulting spacetime is geodesically complete. The internal structure of this nonsingular black hole is analogous to Russian nesting dolls. Namely, after falling into the black hole of radius r{sub g}, an observer, instead of being destroyed at the singularity, gets for a short time into the region with limiting curvature. After that he re-emerges in the near horizon region of a spacetime described by the Schwarzschild metric of a gravitational radius proportional to r{sub g}{sup 1/3}. In the next cycle, after passing the limiting curvature, the observer finds himself within a black hole of even smaller radius proportional to r{sub g}{sup 1/9}, and so on. Finally after a few cycles he will end up in the spacetime where he remains forever at limiting curvature. (orig.)

  16. When Black Holes Collide

    Science.gov (United States)

    Baker, John

    2010-01-01

    Among the fascinating phenomena predicted by General Relativity, Einstein's theory of gravity, black holes and gravitational waves, are particularly important in astronomy. Though once viewed as a mathematical oddity, black holes are now recognized as the central engines of many of astronomy's most energetic cataclysms. Gravitational waves, though weakly interacting with ordinary matter, may be observed with new gravitational wave telescopes, opening a new window to the universe. These observations promise a direct view of the strong gravitational dynamics involving dense, often dark objects, such as black holes. The most powerful of these events may be merger of two colliding black holes. Though dark, these mergers may briefly release more energy that all the stars in the visible universe, in gravitational waves. General relativity makes precise predictions for the gravitational-wave signatures of these events, predictions which we can now calculate with the aid of supercomputer simulations. These results provide a foundation for interpreting expect observations in the emerging field of gravitational wave astronomy.

  17. "Holes": Folklore Redux.

    Science.gov (United States)

    Mascia, Elizabeth G.

    2001-01-01

    Demonstrates that a careful reading of the book for young adults, "Holes" by Louis Sachar, reveals how this contemporary story is grounded in folklore, and that it is this debt to folk literature that allows readers to accept an improbable plot. Shows how the story weaves together elements from traditional folk literature and stretches them across…

  18. The Antarctic Ozone Hole.

    Science.gov (United States)

    Stolarski, Richard S.

    1988-01-01

    Discusses the Airborne Antarctic Ozone Experiment (1987) and the findings of the British Antarctic Survey (1985). Proposes two theories for the appearance of the hole in the ozone layer over Antarctica which appears each spring; air pollution and natural atmospheric shifts. Illustrates the mechanics of both. Supports worldwide chlorofluorocarbon…

  19. Quantum aspects of black holes

    CERN Document Server

    2015-01-01

    Beginning with an overview of the theory of black holes by the editor, this book presents a collection of ten chapters by leading physicists dealing with the variety of quantum mechanical and quantum gravitational effects pertinent to black holes. The contributions address topics such as Hawking radiation, the thermodynamics of black holes, the information paradox and firewalls, Monsters, primordial black holes, self-gravitating Bose-Einstein condensates, the formation of small black holes in high energetic collisions of particles, minimal length effects in black holes and small black holes at the Large Hadron Collider. Viewed as a whole the collection provides stimulating reading for researchers and graduate students seeking a summary of the quantum features of black holes.

  20. Black Hole: The Interior Spacetime

    CERN Document Server

    Ong, Yen Chin

    2016-01-01

    The information loss paradox is often discussed from the perspective of the observers who stay outside of a black hole. However, the interior spacetime of a black hole can be rather nontrivial. We discuss the open problems regarding the volume of a black hole, and whether it plays any role in information storage. We also emphasize the importance of resolving the black hole singularity, if one were to resolve the information loss paradox.

  1. Highlights of X-Stack ExM Deliverable Swift/T

    Energy Technology Data Exchange (ETDEWEB)

    Wozniak, Justin M. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-03-31

    Swift/T is a key success from the ExM: System support for extreme-scale, many-task applications1 X-Stack project, which proposed to use concurrent dataflow as an innovative programming model to exploit extreme parallelism in exascale computers. The Swift/T component of the project reimplemented the Swift language from scratch to allow applications that compose scientific modules together to be build and run on available petascale computers (Blue Gene, Cray). Swift/T does this via a new compiler and runtime that generates and executes the application as an MPI program. We assume that mission-critical emerging exascale applications will be composed as scalable applications using existing software components, connected by data dependencies. Developers wrap native code fragments using a higherlevel language, then build composite applications to form a computational experiment. This exemplifies hierarchical concurrency: lower-level messaging libraries are used for fine-grained parallelism; highlevel control is used for inter-task coordination. These patterns are best expressed with dataflow, but static DAGs (i.e., other workflow languages) limit the applications that can be built; they do not provide the expressiveness of Swift, such as conditional execution, iteration, and recursive functions.

  2. The leading-edge vortex of swift-wing shaped delta wings

    Science.gov (United States)

    Muir, Rowan; Arredondo-Galeana, Abel; Viola, Ignazio Maria

    2017-11-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the Leading-Edge Vortex (LEV) for lift generation in a variety of flight conditions. In this investigation, a model non-slender delta shaped wing with a sharp leading-edge is tested at low Reynolds Number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the un-modified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift-wing shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds Number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta shaped wing. This work received funding from the Engineering and Physical Sciences Research Council [EP/M506515/1] and the Consejo Nacional de Ciencia y Tecnología (CONACYT).

  3. Age-specific survival of reintroduced swift fox in Badlands National Park and surrounding lands

    Science.gov (United States)

    Sasmal, Indrani; Klaver, Robert W.; Jenks, Jonathan A.; Schroeder, Greg M.

    2016-01-01

    In 2003, a reintroduction program was initiated at Badlands National Park (BNP), South Dakota, USA, with swift foxes (Vulpes velox) translocated from Colorado and Wyoming, USA, as part of a restoration effort to recover declining swift fox populations throughout its historical range. Estimates of age-specific survival are necessary to evaluate the potential for population growth of reintroduced populations. We used 7 years (2003–2009) of capture–recapture data of 243 pups, 29 yearlings, and 69 adult swift foxes at BNP and the surrounding area to construct Cormack–Jolly–Seber model estimates of apparent survival within a capture–mark–recapture framework using Program MARK. The best model for estimating recapture probabilities included no differences among age classes, greater recapture probabilities during early years of the monitoring effort than later years, and variation among spring, winter, and summer. Our top ranked survival model indicated pup survival differed from that of yearlings and adults and varied by month and year. The apparent annual survival probability of pups (0.47, SE = 0.10) in our study area was greater than the apparent annual survival probability of yearlings and adults (0.27, SE = 0.08). Our results indicate low survival probabilities for a reintroduced population of swift foxes in the BNP and surrounding areas. Management of reintroduced populations and future reintroductions of swift foxes should consider the effects of relative low annual survival on population demography.

  4. Swift J045106.8-694803: A Highly Magnetised Neutron Star in the Large Magellanic Cloud

    Science.gov (United States)

    Klus, H.; Bartlett, E. S.; Bird, A. J.; Coe, M.; Corbet, R. H. D.; Udalski, A.

    2013-01-01

    We report the analysis of a highly magnetised neutron star in the Large Magellanic Cloud (LMC). The high mass X-ray binary pulsar Swift J045106.8-694803 has been observed with Swift X-ray telescope (XRT) in 2008, The Rossi X-ray Timing Explorer (RXTE) in 2011 and the X-ray Multi-Mirror Mission - Newton (XMM-Newton) in 2012. The change in spin period over these four years indicates a spin-up rate of 5.010.06 s/yr, amongst the highest observed for an accreting pulsar. This spin-up rate can be accounted for using Ghosh and Lambs (1979) accretion theory assuming it has a magnetic field of (1.2 +/= 0.20/0.7) x 10(exp 14) Gauss. This is over the quantum critical field value. There are very few accreting pulsars with such high surface magnetic fields and this is the first of which to be discovered in the LMC. The large spin-up rate is consistent with Swift Burst Alert Telescope (BAT) observations which show that Swift J045106.8-694803 has had a consistently high X-ray luminosity for at least five years. Optical spectra have been used to classify the optical counterpart of Swift J045106.8-694803 as a B0-1 III-V star and a possible orbital period of 21.631 +/- 0.005 days has been found from MACHO optical photometry.

  5. String physics and black holes

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, L. [Stanford Univ., CA (United States). Dept. of Physics; Uglum, J. [Stanford Univ., CA (United States). Dept. of Physics

    1996-02-01

    In these lectures we review the quantum physics of large Schwarzschild black holes. Hawking`s information paradox, the theory of the stretched horizon and the principle of black hole complementarity are covered. We then discuss how the ideas of black hole complementarity may be realized in string theory. Finally, arguments are given that the world may be a hologram. (orig.).

  6. Hole pairs in a spin liquid: Influence of electrostatic hole-hole repulsion

    Science.gov (United States)

    Gazza, Claudio; Martins, George B.; Riera, José; Dagotto, Elbio

    1999-01-01

    The stability of hole bound states in the t-J model including short-range Coulomb interactions is analyzed using computational techniques on ladders with up to 2×30 sites. For a nearest-neighbor (NN) hole-hole repulsion, the two-holes bound state is surprisingly robust and breaks only when the repulsion is several times the exchange J. At ~10% hole doping the pairs break only for a NN repulsion as large as V~4J. Pair-pair correlations remain robust in the regime of hole binding. The results support electronic hole-pairing mechanisms on ladders based on holes moving in spin-liquid backgrounds. Implications in two dimensions are also presented. The need for better estimations of the range and strength of the Coulomb interaction in copper oxides is remarked.

  7. Primary and Presidential Candidates

    DEFF Research Database (Denmark)

    Goddard, Joseph

    2012-01-01

    This article looks at primary and presidential candidates in 2008 and 2012. Evidence suggests that voters are less influenced by candidates’ color, gender, or religious observation than previously. Conversely, markers of difference remain salient in the imaginations of pollsters and journalists...

  8. Seven years with the Swift Supergiant Fast X-ray Transients project

    Science.gov (United States)

    Romano, P.

    2015-09-01

    Supergiant Fast X-ray Transients (SFXTs) are HMXBs with OB supergiant companions. I review the results of the Swift SFXT project, which since 2007 has been exploiting Swift's capabilities in a systematic study of SFXTs and supergiant X-ray binaries (SGXBs) by combining follow-ups of outbursts, when detailed broad-band spectroscopy is possible, with long-term monitoring campaigns, when the out-of-outburst fainter states can be observed. This strategy has led us to measure their duty cycles as a function of luminosity, to extract their differential luminosity distributions in the soft X-ray domain, and to compare, with unprecedented detail, the X-ray variability in these different classes of sources. I also discuss the ;seventh year crisis;, the challenges that the recent Swift observations are making to the prevailing models attempting to explain the SFXT behavior.

  9. Radio Detections During Two State Transitions of the Intermediate-Mass Black Hole HLX-1

    Science.gov (United States)

    Webb, Natalie; Cseh, David; Lenc, Emil; Godet, Olivier; Barret, Didier; Corbel, Stephane; Farrell, Sean; Fender, Robert; Gehrels, Neil; Heywood, Ian

    2012-01-01

    Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (approx. 3 to 20 solar masses) as well as supermassive black holes (approx.. 10(exp 6) to 10(exp 9) Solar Mass) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (approx. 10(exp 2) to 10(exp 5) Solar Mass), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between approx. 9 × 10(exp 3) Solar Mass and approx. 9 × 10(exp 4) Solar Mass.

  10. Nonsingular Black Holes

    CERN Document Server

    Olmo, Gonzalo J

    2011-01-01

    We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius $r_{core}\\approx N_q^{1/2}l_P/3$, where $l_P$ is the Planck length and $N_q$ is the number of electric charges. The singularity is avoided if the mass of the object satisfies the condition $M_0^2\\approx m_P^2 \\alpha_{em}^{3/2} N_q^3/2$, where $m_P$ is the Planck mass and $\\alpha_{em}$ is the fine-structure constant. For astrophysical black holes this amount of charge is so small that their external horizon almost coincides with their Schwarzschild radius. We work within a first-order (Palatini) approach.

  11. Historical range, current distribution, and conservation status of the Swift Fox, Vulpes velox, in North America

    Science.gov (United States)

    Sovada, Marsha A.; Woodward, Robert O.; Igl, Lawrence D.

    2009-01-01

    The Swift Fox (Vulpes velox) was once common in the shortgrass and mixed-grass prairies of the Great Plains of North America. The species' abundance declined and its distribution retracted following European settlement of the plains. By the late 1800s, the species had been largely extirpated from the northern portion of its historical range, and its populations were acutely depleted elsewhere. Swift Fox populations have naturally recovered somewhat since the 1950s, but overall abundance and distribution remain below historical levels. In a 1995 assessment of the species' status under the US Endangered Species Act, the US Fish and Wildlife Service concluded that a designation of threatened or endangered was warranted, but the species was "precluded from listing by higher listing priorities." A major revelation of the 1995 assessment was the recognition that information useful for determining population status was limited. Fundamental information was missing, including an accurate estimate of the species' distribution before European settlement and an estimate of the species' current distribution and trends. The objectives of this paper are to fill those gaps in knowledge. Historical records were compiled and, in combination with knowledge of the habitat requirements of the species, the historical range of the Swift Fox is estimated to be approximately 1.5 million km2. Using data collected between 2001 and 2006, the species' current distribution is estimated to be about 44% of its historical range in the United States and 3% in Canada. Under current land use, approximately 39% of the species' historical range contains grassland habitats with very good potential for Swift Fox occupation and another 10% supports grasslands with characteristics that are less preferred (e.g., a sparse shrub component or taller stature) but still suitable. Additionally, land use on at least 25% of the historical range supports dryland farming, which can be suitable for Swift Fox

  12. Prisons of light : black holes

    Science.gov (United States)

    Ferguson, Kitty

    What is a black hole? Could we survive a visit to one -- perhaps even venture inside? Have we yet discovered any real black holes? And what do black holes teach us about the mysteries of our Universe? These are just a few of the tantalizing questions examined in this tour-de-force, jargon-free review of one of the most fascinating topics in modern science. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light - Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.

  13. Cumulative approaches to track formation under swift heavy ion (SHI) irradiation: Phenomenological correlation with formation energies of Frenkel pairs

    Energy Technology Data Exchange (ETDEWEB)

    Crespillo, M.L., E-mail: mcrespil@utk.edu [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Agulló-López, F., E-mail: fal@uam.es [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Zucchiatti, A. [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain)

    2017-03-01

    Highlights: • Extensive survey formation energies Frenkel pairs and electronic stopping thresholds. • Correlation: track formation thresholds and the energies for Frenkel pair formation. • Formation energies Frenkel pairs discussed in relation to the cumulative mechanisms. • Amorphous track formation mechanisms: defect accumulation models versus melting. • Advantages cumulative models to deal with new hot topics: nuclear-electronic synergy. - Abstract: An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO{sub 3} crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.

  14. Cumulative approaches to track formation under swift heavy ion (SHI) irradiation: Phenomenological correlation with formation energies of Frenkel pairs

    Science.gov (United States)

    Crespillo, M. L.; Agulló-López, F.; Zucchiatti, A.

    2017-03-01

    An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO3 crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.

  15. The December 2015 optical outburst of OJ 287: X-ray and UV time-domain monitor by Swift

    Science.gov (United States)

    Ciprini, S.; Perri, M.; Verrecchia, F.; Valtonen, M.

    2015-12-01

    The Swift satellite is monitoring from 2015 Nov. 28 the BL Lac object OJ 287 (z=0.306). Our Swift X-ray and UV time-domain monitor program has been proposed and granted in response to a predicted, and then observed, phase of increased optical activity from OJ 287 (see, ATel#8372 and ATel#8378).

  16. Expeditious screening of candidate proteins for microbial vaccines.

    Science.gov (United States)

    Zaheer, Rahat; Klima, Cassidy L; McAllister, Tim A

    2015-09-01

    Advancements in high-throughput "omics" technologies have revolutionized the way vaccine candidates are identified. Now every surface expressed protein that an organism produces can be identified in silico and possibly made available for the rapid development of recombinant/subunit vaccines. However, evaluating the antigenicity of a large number of candidate proteins is an immense challenge, typically requiring cloning of several hundred candidates followed by immunogenicity screening. Here we report the development of a rapid, high-throughput method for screening candidate proteins for vaccines. This method involves utilizing a coupled, cell-free transcription-translation system to screen tagged proteins that are captured at the C-termini using appropriate ligand coated wells in 96 well ELISA plates. The template DNA for the cell-free expression is generated by two sequential PCRs and includes gene coding sequences, promoter, terminator, other necessary cis-acting elements and appropriate tag sequences. The process generates expressible candidate proteins containing two different peptide tags at the N- and the C-termini of the protein molecules. Proteins are screened in parallel for their quantity and immunoreactivity with N-terminal tag antibodies and antisera raised against the pathogen of interest, respectively. Normalization against the total detectable bound protein in the control wells allows for the identification of highly immunoreactive candidates. For this study we selected 30 representatives of >300 potential candidate proteins from Mannheimia haemolytica, a bacterial agent of pneumonia in feedlot cattle for expression with N-terminal Strep-II and C-terminal His(x6)-tag and evaluated their relative immunoreactivities using Strep-tactin-HRP and rabbit antisera generated against M. haemolytica. Using this system we were able to swiftly and quantitatively analyze and rank the suitability of proteins to identify potentially viable vaccine candidates, with

  17. Supergiant Fast X-Ray Transients: Swift Results and Theoretical Progress

    Science.gov (United States)

    Farinelli, Ruben; Romano, Patrizia; Vercellone, Stefano; Ceccobello, C.; Titarchuk, L.

    We present an overview of our Supergiant Fast X-ray Transients (SFXT) project, by highlighting the unique observational contribution Swift is giving to this exciting new field. Since 2007 Swift has been detecting outbursts from these fast transients with the BAT and following them intensively for days with the XRT so that we now have a firm estimate of the time SFXTs spend in each intensity phase. We summarize some preliminary results on our XSPEC model that numerically solves the bulk-motion radiative transfer equation with a strong magnetic field, in the Fokker-Planck approximation.

  18. Acoustic Noise Test Report for the SWIFT Wind Turbine in Boulder, CO

    Energy Technology Data Exchange (ETDEWEB)

    Roadman, J.; Huskey, A.

    2013-04-01

    This report summarizes the results of an acoustic noise test that the National Renewable Energy Laboratory (NREL) conducted on the SWIFT wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 11: Acoustic Noise Measurement Techniques, IEC 61400-11 Ed.2.1, 2006-11. However, because the SWIFT is a small turbine, as defined by IEC, NREL used 10-second averages instead of 60-second averages and utilized binning by wind speed instead of regression analysis.

  19. Supersymmetric Dark Matter Candidates

    CERN Document Server

    Ellis, John

    2010-01-01

    After reviewing the theoretical, phenomenological and experimental motivations for supersymmetric extensions of the Standard Model, we recall that supersymmetric relics from the Big Bang are expected in models that conserve R parity. We then discuss possible supersymmetric dark matter candidates, focusing on the lightest neutralino and the gravitino. In the latter case, the next-to-lightest supersymmetric particle is expected to be long-lived, and possible candidates include spartners of the tau lepton, top quark and neutrino. We then discuss the roles of the renormalization-group equations and electroweak symmetry breaking in delimiting the supersymmetric parameter space. We discuss in particular the constrained minimal extension of the Standard Model (CMSSM), in which the supersymmetry-breaking parameters are assumed to be universal at the grand unification scale, presenting predictions from a frequentist analysis of its parameter space. We also discuss astrophysical and cosmological constraints on gravitin...

  20. Superluminal Jets and Other Properties of Black Holes Binaries

    Science.gov (United States)

    Harmon, Alan

    1997-01-01

    Discoveries in the past few years of radio jets in Galactic black hole candidates have provided a link between active galactic nuclei (AGNS) and the compact stars in binary systems. The availability of binary systems relatively close by is an opportunity to learn about the jet production mechanism on a timescale a million times shorter than that of an AGN. Evidence is clearly seen of correlated high energy X-ray and gamma ray emission to radio emission from jets, linking the accretion and jet production mechanisms. objects such as GRS 1915+105, GRO J1655-40 and Cyg X-3 show striking properties which distinguish them from other black hole candidates. Our theoretical understanding of these systems is still in the formative stages. I review some of the most recent multiwavelength data and point out questions raised by these observations.

  1. Thermal BEC Black Holes

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2015-10-01

    Full Text Available We review some features of Bose–Einstein condensate (BEC models of black holes obtained by means of the horizon wave function formalism. We consider the Klein–Gordon equation for a toy graviton field coupled to a static matter current in a spherically-symmetric setup. The classical field reproduces the Newtonian potential generated by the matter source, while the corresponding quantum state is given by a coherent superposition of scalar modes with a continuous occupation number. An attractive self-interaction is needed for bound states to form, the case in which one finds that (approximately one mode is allowed, and the system of N bosons can be self-confined in a volume of the size of the Schwarzschild radius. The horizon wave function formalism is then used to show that the radius of such a system corresponds to a proper horizon. The uncertainty in the size of the horizon is related to the typical energy of Hawking modes: it decreases with the increasing of the black hole mass (larger number of gravitons, resulting in agreement with the semiclassical calculations and which does not hold for a single very massive particle. The spectrum of these systems has two components: a discrete ground state of energy m (the bosons forming the black hole and a continuous spectrum with energy ω > m (representing the Hawking radiation and modeled with a Planckian distribution at the expected Hawking temperature. Assuming the main effect of the internal scatterings is the Hawking radiation, the N-particle state can be collectively described by a single-particle wave-function given by a superposition of a total ground state with energy M = Nm and Entropy 2015, 17 6894 a Planckian distribution for E > M at the same Hawking temperature. This can be used to compute the partition function and to find the usual area law for the entropy, with a logarithmic correction related to the Hawking component. The backreaction of modes with ω > m is also shown to reduce

  2. stu Black Holes Unveiled

    CERN Document Server

    Bellucci, S; Marrani, A; Yeranyan, A

    2008-01-01

    The general solutions of the radial attractor flow equations for extremal black holes, both for non-BPS with non-vanishing central charge Z and for Z=0, are obtained for the so-called stu model, the minimal rank-3 N=2 symmetric supergravity in d=4 space-time dimensions. Comparisons with previous results, as well as the fake supergravity (first order) formalism and an analysis of the BPS bound all along the non-BPS attractor flows and of the marginal stability of corresponding D-brane configurations, are given.

  3. stu Black Holes Unveiled

    Science.gov (United States)

    Bellucci, Stefano; Ferrara, Sergio; Marrani, Alessio; Yeranyan, Armen

    2008-12-01

    The general solutions of the radial attractor flow equations for extremal black holes, both for non-BPS with non-vanishing central charge Z and for Z = 0, are obtained for the so-called stu model, the minimal rank-3 N = 2 symmetric supergravity in d = 4 space-time dimensions. Comparisons with previous results, as well as the fake supergravity (first order) formalism and an analysis of the BPS bound all along the non-BPS attractor flows and of the marginal stability of corresponding D-brane configurations, are given.

  4. Black hole squeezers

    Science.gov (United States)

    Su, Daiqin; Ho, C. T. Marco; Mann, Robert B.; Ralph, Timothy C.

    2017-09-01

    We show that the gravitational quasinormal modes (QNMs) of a Schwarzschild black hole play the role of a multimode squeezer that can generate particles. For a minimally coupled scalar field, the QNMs "squeeze" the initial state of the scalar field (even for the vacuum) and produce scalar particles. The maximal squeezing amplitude is inversely proportional to the cube of the imaginary part of the QNM frequency, implying that the particle generation efficiency is higher for lower decaying QNMs. Our results show that the gravitational perturbations can amplify Hawking radiation.

  5. Artificial ozone holes

    CERN Document Server

    Dolya, S N

    2014-01-01

    This article considers an opportunity of disinfecting a part of the Earth surface, occupying a large area of ten thousand square kilometers. The sunlight will cause dissociation of molecular bromine into atoms; each bromine atom kills thirty thousand molecules of ozone. Each bromine plate has a mass of forty milligrams grams and destroys ozone in the area of hundred square meters. Thus, to form the ozone hole over the area of ten thousand square kilometers, it is required to have the total mass of bromine equal to the following four tons.

  6. Artificial black holes

    CERN Document Server

    Visser, Matt; Volovik, Grigory E

    2009-01-01

    Physicists are pondering on the possibility of simulating black holes in the laboratory by means of various "analog models". These analog models, typically based on condensed matter physics, can be used to help us understand general relativity (Einstein's gravity); conversely, abstract techniques developed in general relativity can sometimes be used to help us understand certain aspects of condensed matter physics. This book contains 13 chapters - written by experts in general relativity, particle physics, and condensed matter physics - that explore various aspects of this two-way traffic.

  7. Black holes in massive gravity

    CERN Document Server

    Babichev, Eugeny

    2015-01-01

    We review the black hole solutions of the ghost-free massive gravity theory and its bimetric extension and outline the main results on the stability of these solutions against small perturbations. Massive (bi)-gravity accommodates exact black hole solutions, analogous to those of General Relativity. In addition to these solutions, hairy black holes -- solutions with no correspondent in General Relativity -- have been found numerically, whose existence is a natural consequence of the absence of the Birkhoff's theorem in these theories. The existence of extra propagating degrees of freedom, makes the stability properties of these black holes richer and more complex than those of General Relativity. In particular, the bi-Schwarzschild black hole exhibits an unstable spherically symmetric mode, while the bi-Kerr geometry is also generically unstable, both against the spherical mode and against superradiant instabilities. If astrophysical black holes are described by these solutions, the superradiant instability o...

  8. Black Hole's 1/N Hair

    CERN Document Server

    Dvali, Gia

    2013-01-01

    According to the standard view classically black holes carry no hair, whereas quantum hair is at best exponentially weak. We show that suppression of hair is an artifact of the semi-classical treatment and that in the quantum picture hair appears as an inverse mass-square effect. Such hair is predicted in the microscopic quantum description in which a black hole represents a self-sustained leaky Bose-condensate of N soft gravitons. In this picture the Hawking radiation is the quantum depletion of the condensate. Within this picture we show that quantum black hole physics is fully compatible with continuous global symmetries and that global hair appears with the strength B/N, where B is the global charge swallowed by the black hole. For large charge this hair has dramatic effect on black hole dynamics. Our findings can have interesting astrophysical consequences, such as existence of black holes with large detectable baryonic and leptonic numbers.

  9. Simultaneous INTEGRAL, RXTE, Swift and FT South observations of the transition of GX 339-4

    NARCIS (Netherlands)

    Cadolle Bel, M.; Kuulkers, E.; Ibarra, A.; Diaz Trigo, M.; Tomsick, J.; Rodriguez, J.; Prat, L.; Corbel, S.; Russell, D.M.; Altamirano, D.; Lewis, F.; Bozzo, E.; Turler, M.; Ferrigno, C.

    2010-01-01

    As GX 339-4 has started to leave the Low/Hard State (ATel #2545), we triggered the 2nd part of our INTEGRAL campaign on GX 339-4 in the declining phase of the hard X-ray band, as well as contemporaneous Swift observations. The source was observed by INTEGRAL for 158 ks between April 15 (01:57 UTC)

  10. Swift as sound. Design and evolution of the echolocation system in Swiftlets (Apodidae : Collocaliini)

    NARCIS (Netherlands)

    Thomassen, H.A.

    2005-01-01

    The thesis describes the design and evolution of echolocation in the South and Southeast Asian Swiftlets. It starts explaining the molecular phylogenetics of Swiftlets, which is used in subsequent chapters. Echolocation calls and social vocalisations of Swifts are compared between species and with

  11. Mindless reading revisited: an analysis based on the SWIFT model of eye-movement control.

    Science.gov (United States)

    Nuthmann, Antje; Engbert, Ralf

    2009-02-01

    In this article, we revisit the mindless reading paradigm from the perspective of computational modeling. In the standard version of the paradigm, participants read sentences in both their normal version as well as the transformed (or mindless) version where each letter is replaced with a z. z-String scanning shares the oculomotor requirements with reading but none of the higher-level lexical and semantic processes. Here we use the z-string scanning task to validate the SWIFT model of saccade generation [Engbert, R., Nuthmann, A., Richter, E., & Kliegl, R. (2005). SWIFT: A dynamical model of saccade generation during reading. Psychological Review, 112(4), 777-813] as an example for an advanced theory of eye-movement control in reading. We test the central assumption of spatially distributed processing across an attentional gradient proposed by the SWIFT model. Key experimental results like prolonged average fixation durations in z-string scanning compared to normal reading and the existence of a string-length effect on fixation durations and probabilities were reproduced by the model, which lends support to the model's assumptions on visual processing. Moreover, simulation results for patterns of regressive saccades in z-string scanning confirm SWIFT's concept of activation field dynamics for the selection of saccade targets.

  12. INTEGRAL and Swift follow-up observations of XMMSL1 J171900.4- 353217

    DEFF Research Database (Denmark)

    Pavan, L.; Terrier, R.; Bozzo, E.

    2010-01-01

    Following the detection of hard X-ray emission from XMMSL1 J171900.4-353217 (Atel #2607) with INTEGRAL (Atel #2803), a Swift/XRT follow-up observation (2 ks) was performed on 2010 August 20 from 13:03 to 14:53, simultaneously with the newly INTEGRAL observation of the same FOV (2010 August 19 at ...

  13. Timing and spectral properties of the accreting millisecond pulsar SWIFT J1756.9-2508

    NARCIS (Netherlands)

    Linares, M.; Wijnands, R.; van der Klis, M.; Krimm, H.; Markwardt, C.B.; Chakrabarty, D.

    2008-01-01

    SWIFT J1756.9-2508 is one of the few accreting millisecond pulsars (AMPs) discovered to date. We report here the results of our analysis of its aperiodic X-ray variability, as measured with the Rossi X-Ray Timing Explorer during the 2007 outburst of the source. We detect strong (~35%) flat-topped

  14. Swift/BAT detection of a burst from SGR J1745-29

    NARCIS (Netherlands)

    Kennea, J.A.; Burrows, D.N.; Cummings, J.; Kouveliotou, C.; Degenaar, N.; Reynolds, M.T.; Miller, J.M.; Wijnands, R.

    2013-01-01

    At 11:17:26 UT on June 7th, 2013 Swift/BAT triggered on a burst from the region near Sgr A*, which contains the currently active magnetar SGR J1745-29 (Kennea et al. 2013; Mori et al. 2013). The initial onboard data showed a short duration single soft peak < 0.32s in duration (Barthelmy et al., GCN

  15. Nucleation control and separation of paracetamol polymorphs through swift cooling crystallization process

    Science.gov (United States)

    Sudha, C.; Srinivasan, K.

    2014-09-01

    Polymorphic nucleation behavior of pharmaceutical solid paracetamol has been investigated by performing swift cooling crystallization process. Saturated aqueous solution prepared at 318 K was swiftly cooled to 274 K in steps of every 1 K in the temperature range from 274 K to 313 K with uniform stirring of 100 rpm. The resultant supersaturation generated in the mother solution favours the nucleation of three different polymorphs of paracetamol. Lower supersaturation region σ=0.10-0.83 favours stable mono form I; the intermediate supersaturation region σ=0.92-1.28 favours metastable ortho form II and the higher supersaturation region σ=1.33-1.58 favours unstable form III polymorphic nucleation. Depending upon the level of supersaturation generated during swift cooling process and the corresponding solubility limit and metastable zone width (MSZW) of each polymorph, the nucleation of a particular polymorph occurs in the system. The type of polymorphs was identified by in-situ optical microscopy and the internal structure was confirmed by Powder X-ray diffraction (PXRD) study. By this novel approach, the preferred nucleation regions of all the three polymorphs of paracetamol are optimized in terms of different cooling ranges employed during the swift cooling process. Also solution mediated polymorphic transformations from unstable to mono and ortho to mono polymorphs have been studied by in-situ.

  16. Understanding Swift Trust to Improve Interagency Collaboration in New York City

    Science.gov (United States)

    2012-09-01

    Performance,” Journal of Managerial Psychology 21, no. 8 (2006): 715, http://www.divisionescolpsic.org/organizacional/ articulos -docs...organizacional/ articulos - docs/Dysfun_culture_drive%20perfor.pdf. Beck, Tammy E. PhD. “Understanding Swift Trust in Temporary Interorganizational

  17. Swift follow-up observations of iPTF16abc

    Science.gov (United States)

    Cao, Yi; Kasliwal, Mansi M.; Cenk, S. Bradley

    2016-04-01

    We triggered Swift to observe the young type Ia supernova iPTF16abc (ATel#8907, ATel#8909) under our ToO program (PI: Kasliwal; program ID: 1215232). The first visit was undertaken around UT April 5.4, about 12 hours after our trigger.

  18. Swift observations of the 2006 outburst of the recurrent nova RS Ophiuchi

    DEFF Research Database (Denmark)

    Vaytet, N. M. H.; O'Brien, T. J.; Bode, M. F.

    2007-01-01

    Following the early Swift X-ray observations of the latest outburst of the recurrent nova RS Ophiuchi in February 2006 (Paper I), we present new 1D hydrodynamical models of the system which take into account all three phases of the remnant evolution. The models suggest a novel way of modelling th...

  19. Swift/XRT observation of the on-going outburst from Terzan 6

    Science.gov (United States)

    Bozzo, E.; Sanna, A.

    2017-10-01

    Following the discovery of an on-going outburst from the direction of the Globular Cluster Terzan 6 (ATel #10832), a Swift/XRT ToO in PC mode has been requested in order to improve the X-ray position and confirm the possibility that the new outburst is from the known low mass X-ray binary GRS 1747-312.

  20. The Swift Gamma-ray Burst Explorer Mission at Penn State

    Science.gov (United States)

    Nousek, J.; Burrows, D.; Chester, M.; Roming, P.; Gehrels, N.; Swift Team

    2000-12-01

    The Swift GRB Explorer mission is designed to discover ~ 1000 new gamma-ray bursts in its three year planned life, and immediately (within tens of seconds) to start simultaneous X-ray, optical and ultraviolet observations of the GRB afterglow. After its planned launch in September, 2003, it will collect an impressive database of gamma ray bursts (reaching more sensitive limits than BATSE); uniform X-ray/UV/optical monitoring of afterglows (with a dedicated weatherless observatory with broad multi-wavelength imaging capability); and rapid followup by other observatories (utilizing a continuous ground link with burst alerts and data posted immediately to the GCN). The Penn State Swift responsibilities include development of the X-ray Telescope (with CCDs from the University of Leicester and X-ray mirrors from OAB); the UV/Optical Telescope (with instrument fabrication at MSSL and SwRI); and development of the Mission Operations Center at PSU (with support from Omitron Corp.). After launch Swift will be operated from Penn State, with data analysis pipelines and data archives at Goddard Space Flight Center, Leicester and the Italian Science Data Center. The mission, lead by Neil Gehrels of GSFC, has successfully concluded the Preliminary Design Review process, including the spacecraft to be built by SpectrumAstro. We show the current status of the PSU lead portions of the mission. Funding for the Swift project at PSU is provided by NASA Contract NAS5-00136.

  1. Ontogeny of swift fox Vulpes velox vocalizations: production, usage and response

    DEFF Research Database (Denmark)

    Darden, Safi-Kirstine Klem; Dabelsteen, Torben

    2006-01-01

    in the swift fox Vulpes velox, using recordings and observations of captive foxes from the time of natal den emergence (age 3-4 weeks) to the time of natal dispersal in the wild (age 4-5 months). We first classified adult vocalizations used during the mating and pup rearing seasons into vocal types (19 types...

  2. Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion

    Science.gov (United States)

    Motta, S. E.; Kajava, J. J. E.; Sánchez-Fernández, C.; Beardmore, A. P.; Sanna, A.; Page, K. L.; Fender, R.; Altamirano, D.; Charles, P.; Giustini, M.; Knigge, C.; Kuulkers, E.; Oates, S.; Osborne, J. P.

    2017-10-01

    The black hole (BH) binary V404 Cyg entered the outburst phase in 2015 June after 26 yr of X-ray quiescence, and with its behaviour broke the outburst evolution pattern typical of most BH binaries. We observed the entire outburst with the Swift satellite and performed time-resolved spectroscopy of its most active phase, obtaining over a thousand spectra with exposures from tens to hundreds of seconds. All the spectra can be fitted with an absorbed power-law model, which most of the time required the presence of a partial covering. A blueshifted iron-Kα line appears in 10 per cent of the spectra together with the signature of high column densities, and about 20 per cent of the spectra seem to show signatures of reflection. None of the spectra showed the unambiguous presence of soft disc-blackbody emission, while the observed bolometric flux exceeded the Eddington value in 3 per cent of the spectra. Our results can be explained assuming that the inner part of the accretion flow is inflated into a slim disc that both hides the innermost (and brightest) regions of the flow, and produces a cold, clumpy, high-density outflow that introduces the high absorption and fast spectral variability observed. We argue that the BH in V404 Cyg might have been accreting erratically or even continuously at Eddington/super-Eddington rates - thus sustaining a surrounding slim disc - while being partly or completely obscured by the inflated disc and its outflow. Hence, the largest flares produced by the source might not be accretion-driven events, but instead the effects of the unveiling of the extremely bright source hidden within the system.

  3. Black Holes in Higher Dimensions

    Directory of Open Access Journals (Sweden)

    Reall Harvey S.

    2008-09-01

    Full Text Available We review black-hole solutions of higher-dimensional vacuum gravity and higher-dimensional supergravity theories. The discussion of vacuum gravity is pedagogical, with detailed reviews of Myers–Perry solutions, black rings, and solution-generating techniques. We discuss black-hole solutions of maximal supergravity theories, including black holes in anti-de Sitter space. General results and open problems are discussed throughout.

  4. Teachers Candidates' Reviews on Teacher Candidate Training System

    Science.gov (United States)

    Altintas, Sedat; Görgen, Izzet

    2017-01-01

    In our country, as a result of the appointment in some different disciplines, nearly 30000 teacher candidates could be a part of education system. Also, a new revision has been completed on teacher candidate training and it has been put into action. Teacher candidates have been trained for six months after they have been appointed. These teachers…

  5. Relativistic jet activity from the tidal disruption of a star by a massive black hole.

    Science.gov (United States)

    Burrows, D N; Kennea, J A; Ghisellini, G; Mangano, V; Zhang, B; Page, K L; Eracleous, M; Romano, P; Sakamoto, T; Falcone, A D; Osborne, J P; Campana, S; Beardmore, A P; Breeveld, A A; Chester, M M; Corbet, R; Covino, S; Cummings, J R; D'Avanzo, P; D'Elia, V; Esposito, P; Evans, P A; Fugazza, D; Gelbord, J M; Hiroi, K; Holland, S T; Huang, K Y; Im, M; Israel, G; Jeon, Y; Jeon, Y-B; Jun, H D; Kawai, N; Kim, J H; Krimm, H A; Marshall, F E; P Mészáros; Negoro, H; Omodei, N; Park, W-K; Perkins, J S; Sugizaki, M; Sung, H-I; Tagliaferri, G; Troja, E; Ueda, Y; Urata, Y; Usui, R; Antonelli, L A; Barthelmy, S D; Cusumano, G; Giommi, P; Melandri, A; Perri, M; Racusin, J L; Sbarufatti, B; Siegel, M H; Gehrels, N

    2011-08-24

    Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

  6. Black holes and the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, Barcelona, 08028 Spain (Spain); Vilenkin, Alexander; Zhang, Jun, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu, E-mail: jun.zhang@tufts.edu [Institute of Cosmology, Tufts University, 574 Boston Ave, Medford, MA, 02155 (United States)

    2016-02-01

    Vacuum bubbles may nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the bubbles quickly dissipate their kinetic energy; they come to rest with respect to the Hubble flow and eventually form black holes. The fate of the bubble itself depends on the resulting black hole mass. If the mass is smaller than a certain critical value, the bubble collapses to a singularity. Otherwise, the bubble interior inflates, forming a baby universe, which is connected to the exterior FRW region by a wormhole. A similar black hole formation mechanism operates for spherical domain walls nucleating during inflation. As an illustrative example, we studied the black hole mass spectrum in the domain wall scenario, assuming that domain walls interact with matter only gravitationally. Our results indicate that, depending on the model parameters, black holes produced in this scenario can have significant astrophysical effects and can even serve as dark matter or as seeds for supermassive black holes. The mechanism of black hole formation described in this paper is very generic and has important implications for the global structure of the universe. Baby universes inside super-critical black holes inflate eternally and nucleate bubbles of all vacua allowed by the underlying particle physics. The resulting multiverse has a very non-trivial spacetime structure, with a multitude of eternally inflating regions connected by wormholes. If a black hole population with the predicted mass spectrum is discovered, it could be regarded as evidence for inflation and for the existence of a multiverse.

  7. Thermodynamics of Accelerating Black Holes.

    Science.gov (United States)

    Appels, Michael; Gregory, Ruth; Kubizňák, David

    2016-09-23

    We address a long-standing problem of describing the thermodynamics of an accelerating black hole. We derive a standard first law of black hole thermodynamics, with the usual identification of entropy proportional to the area of the event horizon-even though the event horizon contains a conical singularity. This result not only extends the applicability of black hole thermodynamics to realms previously not anticipated, it also opens a possibility for studying novel properties of an important class of exact radiative solutions of Einstein equations describing accelerated objects. We discuss the thermodynamic volume, stability, and phase structure of these black holes.

  8. Hole dynamics in noble metals

    OpenAIRE

    Campillo, I.; Rubio, A.; Pitarke, J. M.; Goldmann, A.; Echenique, P. M.

    2000-01-01

    We present a detailed analysis of hole dynamics in noble metals (Cu and Au), by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d-holes in noble metals exhibit longer inelastic lifetimes than excited sp-electrons, in agreement with experiment. The density of states available for d-hole decay is larger than that for the decay of excited electrons; however, th...

  9. The leading-edge vortex of swift wing-shaped delta wings

    Science.gov (United States)

    Muir, Rowan Eveline; Arredondo-Galeana, Abel; Viola, Ignazio Maria

    2017-08-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing.

  10. The leading-edge vortex of swift wing-shaped delta wings

    Science.gov (United States)

    Muir, Rowan Eveline; Arredondo-Galeana, Abel

    2017-01-01

    Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing. PMID:28878968

  11. Serologic survey for canine infectious diseases among sympatric swift foxes (Vulpes velox) and coyotes (Canis latrans) in southeastern Colorado.

    Science.gov (United States)

    Gese, Eric M; Karki, Seija M; Klavetter, Mead L; Schauster, Edward R; Kitchen, Ann M

    2004-10-01

    Swift foxes (Vulpes velox) and coyotes (Canis latrans) are sympatric canids distributed throughout many regions of the Great Plains of North America. The prevalence of canid diseases among these two species where they occur sympatrically is presently unknown. From January 1997 to January 2001, we collected blood samples from 89 swift foxes and 122 coyotes on the US Army Piñon Canyon Maneuver Site, Las Animas County, SE Colorado (USA). Seroprevalence of antibodies against canine parvovirus (CPV) was 71% for adult (> 9 mo old) and 38% for juvenile (< or = 9 mo old) swift foxes. Adult (<1 yr old) and juvenile (<1 yr old) coyotes had a seroprevalence for CPV of 96% and 78%, respectively. Presence of antibodies against canine distemper virus (CDV) was 5% for adult foxes and 0% for juvenile foxes. Seroprevalence of CDV was 46% for adult coyotes and 18% for juvenile coyotes. No swift foxes had canine adenovirus (CAV) antibodies, whereas 81% and 63% of adult and juvenile coyotes, respectively, had antibodies for CAV. Seroprevalence of antibodies against Yersinia pestis was 68% among adult foxes and 34% among juvenile swift foxes. Seroprevalence of Y. pestis antibodies was 90% and 70% for adult and juvenile coyotes, respectively. No swift foxes had antibodies against Francisella tularensis, whereas seroprevalence was 4% among both adult and juvenile coyotes. Antibodies against CPV and plague were common in both species, whereas antibodies against CDV and CAV were more prevalent in coyotes compared to swift foxes.

  12. Possible vector dissemination by swift foxes following a plague epizootic in black-tailed prairie dogs in northwestern Texas.

    Science.gov (United States)

    McGee, Brady K; Butler, Matthew J; Pence, Danny B; Alexander, James L; Nissen, Janet B; Ballard, Warren B; Nicholson, Kerry L

    2006-04-01

    To determine whether swift foxes (Vulpes velox) could facilitate transmission of Yersinia pestis to uninfected black-tailed prairie dog (Cynomys ludovicianus) colonies by acquiring infected fleas, ectoparasite and serologic samples were collected from swift foxes living adjacent to prairie dog towns during a 2004 plague epizootic in northwestern Texas, USA. A previous study (1999-2001) indicated that these swift foxes were infested almost exclusively with the flea Pulex irritans. Black-tailed prairie dogs examined from the study area harbored only Pulex simulans and Oropsylla hirsuta. Although P. irritans was most common, P. simulans and O. hirsuta were collected from six swift foxes and a single coyote (Canis latrans) following the plague epizootic. Thus, both of these canids could act as transport hosts (at least temporarily) of prairie dog fleas following the loss of their normal hosts during a plague die-off. All six adult swift foxes tested positive for antibodies to Y. pestis. All 107 fleas from swift foxes tested negative for Y. pestis by mouse inoculation. Although swift foxes could potentially carry Y. pestis to un-infected prairie dog colonies, we believe they play only a minor role in plague epidemiology, considering that they harbored just a few uninfected prairie dog fleas (P. simulans and O. hirsuta).

  13. Logarithmic corrections to entropy of magnetically charged AdS4 black holes

    Directory of Open Access Journals (Sweden)

    Imtak Jeon

    2017-11-01

    Full Text Available Logarithmic terms are quantum corrections to black hole entropy determined completely from classical data, thus providing a strong check for candidate theories of quantum gravity purely from physics in the infrared. We compute these terms in the entropy associated to the horizon of a magnetically charged extremal black hole in AdS×4S7 using the quantum entropy function and discuss the possibility of matching against recently derived microscopic expressions.

  14. Logarithmic corrections to entropy of magnetically charged AdS4 black holes

    Science.gov (United States)

    Jeon, Imtak; Lal, Shailesh

    2017-11-01

    Logarithmic terms are quantum corrections to black hole entropy determined completely from classical data, thus providing a strong check for candidate theories of quantum gravity purely from physics in the infrared. We compute these terms in the entropy associated to the horizon of a magnetically charged extremal black hole in AdS4×S7 using the quantum entropy function and discuss the possibility of matching against recently derived microscopic expressions.

  15. ARE SPECTRAL AND TIMING CORRELATIONS SIMILAR IN DIFFERENT SPECTRAL STATES IN BLACK HOLE X-RAY BINARIES?

    Energy Technology Data Exchange (ETDEWEB)

    Kalamkar, M.; Klis, M. van der [Astronomical Institute, “Anton Pannekoek,” University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Reynolds, M. T.; Miller, J. M. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Altamirano, D., E-mail: maithili@oa-roma.inaf.it [School of Physics and Astronomy, University of Southampton, Southampton, Hampshire SO17 1BJ (United Kingdom)

    2015-03-20

    We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5-0127, and GX 339-4 with the Swift X-ray Telescope (XRT). The bandpass of the XRT has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a correlated spectral and variability study, with variability from both components of the accretion flow. We present for the first time a combined study of the evolution of spectral parameters (disk temperature and radius) and timing parameters (frequency and strength) of all power spectral components in different spectral states. Comparison of the correlations in different spectral states shows that the frequency and strength of the power spectral components exhibit dependencies on the disk temperature that are different in the (low-)hard and the hard-intermediate states (HIMSs); most of these correlations that are clearly observed in the HIMS (in MAXI J1659-152 and GX 339-4) are not seen in the (low-)hard state (in GX 339-4 and SWIFT J1753.5-0127). Also, the responses of the individual frequency components to changes in the disk temperature are markedly different from one component to the next. Hence, the spectral-timing evolution cannot be explained by a single correlation that spans both these spectral states. We discuss our findings in the context of the existing models proposed to explain the origin of variability.

  16. Optimized candidal biofilm microtiter assay

    NARCIS (Netherlands)

    Krom, Bastiaan P.; Cohen, Jesse B.; Feser, Gail E. McElhaney; Cihlar, Ronald L.

    Microtiter based candidal biofilm formation is commonly being used. Here we describe the analysis of factors influencing the development of candidal biofilms such as the coating with serum, growth medium and pH. The data reported here show that optimal candidal biofilm formation is obtained when

  17. Black holes under external influence £

    Indian Academy of Sciences (India)

    KTF MFF UK

    of the flux of external fields across charged and rotating black holes which are approaching extremal states. Recently this effect has been shown to occur for black hole solutions in string theory. We also discuss black holes surrounded by rings and disks and rotating black holes accelerated by strings. Keywords. Black holes ...

  18. iOS game development : Mobile game development with Swift programming language and SceneKit framework

    OpenAIRE

    Koskenseppä, Juuso

    2016-01-01

    The purpose of the thesis was to create an iOS game that could be deemed complete enough, so it could be published in Apple’s App Store. This meant fulfilling different guide-lines specified by Apple. The project was carried out by using Apple’s new Swift programming language and SceneKit framework, with an intention to see how they work for iOS game development. The immaturity of Swift programming language led to several code rewrites, every time a newer Swift version was released. T...

  19. VizieR Online Data Catalog: Swift obs. of the superluminous SNI ASASSN-15lh (Brown+, 2016)

    Science.gov (United States)

    Brown, P. J.; Yang, Y.; Cooke, J.; Olaes, M.; Quimby, R. M.; Baade, D.; Gehrels, N.; Hoeflich, P.; Maund, J.; Mould, J.; Wang, L.; Wheeler, J. C.

    2016-11-01

    ASASSN-15lh, was discovered by the ASAS-SN on UT 2015 June 14.25 (MJD 57187.25). Observations with Swift began 2015 June 24 00:37:49 (MJD 57197). The early UVOT data were reported by Dong+ (2016Sci...351..257D). We triggered our Swift Guest Investigator programs "Ultraviolet Properties of Superluminous Supernovae over Ten Billion Years" (PI: Brown) to obtain UV/optical photometry with Swift/UVOT and "Late-time X-Rays from Superluminous Supernovae: How Hard Could it Be?" (PI: Quimby). We have reduced all of the data obtained through 2016 April 1. (2 data files).

  20. Black-Hole Mass Measurements

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2004-01-01

    The applicability and apparent uncertainties of the techniques currently available for measuring or estimating black-hole masses in AGNs are briefly summarized.......The applicability and apparent uncertainties of the techniques currently available for measuring or estimating black-hole masses in AGNs are briefly summarized....

  1. Black Holes in Our Universe

    Indian Academy of Sciences (India)

    Black holes are bits of space, or more precisely, 'space-time', from which even light cannot escape, because they are regions of extremely strong gravity. We now know that black holes, es- pecially those that are a million times heavier than our Sun or more, i.e., 'supermassive', are abundant in our universe, occur- ring in the ...

  2. Drilling miniature holes, Part III

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, L.K.

    1978-07-01

    Miniature components for precision electromechanical mechanisms such as switches, timers, and actuators typically require a number of small holes. Because of the precision required, the workpiece materials, and the geometry of the parts, most of these holes must be produced by conventional drilling techniques. The use of such techniques is tedious and often requires considerable trial and error to prevent drill breakage, minimize hole mislocation and variations in hole diameter. This study of eight commercial drill designs revealed that printed circuit board drills produced better locational and size repeatability than did other drills when centerdrilling was not used. Boring holes 1 mm in dia, or less, as a general rule did not improve hole location in brass or stainless steel. Hole locations of patterns of 0.66-mm holes can be maintained within 25.4-..mu..m diametral positional tolerance if setup misalignments can be eliminated. Size tolerances of +- 3.8 ..mu..m can be maintained under some conditions when drilling flat plates. While these levels of precision are possible with existing off-the-shelf drills, they may not be practical in many cases.

  3. ATLAS simulated black hole event

    CERN Multimedia

    Pequenão, J

    2008-01-01

    The simulated collision event shown is viewed along the beampipe. The event is one in which a microscopic-black-hole was produced in the collision of two protons (not shown). The microscopic-black-hole decayed immediately into many particles. The colors of the tracks show different types of particles emerging from the collision (at the center).

  4. Asymmetric black dyonic holes

    Directory of Open Access Journals (Sweden)

    I. Cabrera-Munguia

    2015-04-01

    Full Text Available A 6-parametric asymptotically flat exact solution, describing a two-body system of asymmetric black dyons, is studied. The system consists of two unequal counterrotating Kerr–Newman black holes, endowed with electric and magnetic charges which are equal but opposite in sign, separated by a massless strut. The Smarr formula is generalized in order to take into account their contribution to the mass. The expressions for the horizon half-length parameters σ1 and σ2, as functions of the Komar parameters and of the coordinate distance, are displayed, and the thermodynamic properties of the two-body system are studied. Furthermore, the seven physical parameters satisfy a simple algebraic relation which can be understood as a dynamical scenario, in which the physical properties of one body are affected by the ones of the other body.

  5. GRS 1758–258: RXTE Monitoring of a Rare Persistent Hard State Black Hole

    Directory of Open Access Journals (Sweden)

    M. Obst

    2011-01-01

    Full Text Available GRS 1758–258 is the least studied of the three persistent black hole X-ray binaries in our Galaxy. It is also one of only two known black hole candidates, including all black hole transients, which shows a decrease of its 3-10 keV flux when entering the thermally dominated soft state, rather than an increase.We present the spectral evolution of GRS 1758–258 from RXTE-PCA observations spanning a time of about 11 years from 1996 to 2007. During this time, seven dim soft states are detected. We also consider INTEGRAL monitoring observations of the source and compare the long-term behavior to that of the bright persistent black hole X-ray binary Cygnus X-1. We discuss the observed state transitions in the light of physical scenarios for black hole transitions.

  6. MicroBlack Holes Thermodynamics in the Presence of Quantum Gravity Effects

    Directory of Open Access Journals (Sweden)

    H. Soltani

    2014-01-01

    Full Text Available Black hole thermodynamics is corrected in the presence of quantum gravity effects. Some phenomenological aspects of quantum gravity proposal can be addressed through generalized uncertainty principle (GUP which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of both a minimal measurable length and a maximal momentum on the thermodynamics of TeV-scale black holes. We then extend our study to the case that there are all natural cutoffs as minimal length, minimal momentum, and maximal momentum simultaneously. We also generalize our study to the model universes with large extra dimensions (LED. In this framework existence of black holes remnants as a possible candidate for dark matter is discussed. We study probability of black hole production in the Large Hadronic Collider (LHC and we show this rate decreasing for sufficiently large values of the GUP parameter.

  7. Magnetic fields around black holes

    Science.gov (United States)

    Garofalo, David A. G.

    Active Galactic Nuclei are the most powerful long-lived objects in the universe. They are thought to harbor supermassive black holes that range from 1 million solar masses to 1000 times that value and possibly greater. Theory and observation are converging on a model for these objects that involves the conversion of gravitational potential energy of accreting gas to radiation as well as Poynting flux produced by the interaction of the rotating spacetime and the electromagnetic fields originating in the ionized accretion flow. The presence of black holes in astrophysics is taking center stage, with the output from AGN in various forms such as winds and jets influencing the formation and evolution of the host galaxy. This dissertation addresses some of the basic unanswered questions that plague our current understanding of how rotating black holes interact with their surrounding magnetized accretion disks to produce the enormous observed energy. Two magnetic configurations are examined. The first involves magnetic fields connecting the black hole with the inner accretion disk and the other involves large scale magnetic fields threading the disk and the hole. We study the effects of the former type by establishing the consequences that magnetic torques between the black hole and the inner accretion disk have on the energy dissipation profile. We attempt a plausible explanation to the observed "Deep Minimum" state in the Seyfert galaxy MCG-6- 30-15. For the latter type of magnetic geometry, we study the effects of the strength of the magnetic field threading the black hole within the context of the cherished Blandford & Znajek mechanism for black hole spin energy extraction. We begin by addressing the problem in the non-relativistic regime where we find that the black hole-threading magnetic field is stronger for greater disk thickness, larger magnetic Prandtl number, and for a larger accretion disk. We then study the problem in full relativity where we show that our

  8. When Charged Black Holes Merge

    Science.gov (United States)

    Kohler, Susanna

    2016-08-01

    Most theoretical models assume that black holes arent charged. But a new study shows that mergers of charged black holes could explain a variety of astrophysical phenomena, from fast radio bursts to gamma-ray bursts.No HairThe black hole no hair theorem states that all black holes can be described by just three things: their mass, their spin, and their charge. Masses and spins have been observed and measured, but weve never measured the charge of a black hole and its widely believed that real black holes dont actually have any charge.That said, weve also never shown that black holes dont have charge, or set any upper limits on the charge that they might have. So lets suppose, for a moment, that its possible for a black hole to be charged. How might that affect what we know about the merger of two black holes? A recent theoretical study by Bing Zhang (University of Nevada, Las Vegas) examines this question.Intensity profile of a fast radio burst, a sudden burst of radio emission that lasts only a few milliseconds. [Swinburne Astronomy Productions]Driving TransientsZhangs work envisions a pair of black holes in a binary system. He argues that if just one of the black holes carries charge possibly retained by a rotating magnetosphere then it may be possible for the system to produce an electromagnetic signal that could accompany gravitational waves, such as a fast radio burst or a gamma-ray burst!In Zhangs model, the inspiral of the two black holes generates a global magnetic dipole thats perpendicular to the plane of the binarys orbit. The magnetic flux increases rapidly as the separation between the black holes decreases, generating an increasingly powerful magnetic wind. This wind, in turn, can give rise to a fast radio burst or a gamma-ray burst, depending on the value of the black holes charge.Artists illustration of a short gamma-ray burst, thought to be caused by the merger of two compact objects. [ESO/A. Roquette]Zhang calculates lower limits on the charge

  9. Prisons of Light - Black Holes

    Science.gov (United States)

    Ferguson, Kitty

    1998-05-01

    In this jargon-free review of one of the most fascinating topics in modern science, acclaimed science writer Kitty Ferguson examines the discovery of black holes, their nature, and what they can teach us about the mysteries of the universe. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light--Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.

  10. String-Corrected Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Hubeny, V.

    2005-01-12

    We investigate the geometry of four dimensional black hole solutions in the presence of stringy higher curvature corrections to the low energy effective action. For certain supersymmetric two charge black holes these corrections drastically alter the causal structure of the solution, converting seemingly pathological null singularities into timelike singularities hidden behind a finite area horizon. We establish, analytically and numerically, that the string-corrected two-charge black hole metric has the same Penrose diagram as the extremal four-charge black hole. The higher derivative terms lead to another dramatic effect--the gravitational force exerted by a black hole on an inertial observer is no longer purely attractive. The magnitude of this effect is related to the size of the compactification manifold.

  11. Are LIGO's Black Holes Made From Smaller Black Holes?

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    The recent successes of the Laser Interferometer Gravitational-Wave Observatory (LIGO) has raised hopes that several long-standing questions in black-hole physics will soon be answerable. Besides revealing how the black-hole binary pairs are built, could detections with LIGO also reveal how the black holes themselves form?Isolation or HierarchyThe first detection of gravitational waves, GW150914, was surprising for a number of reasons. One unexpected result was the mass of the two black holes that LIGO saw merging: they were a whopping 29 and 36 solar masses.On the left of this schematic, two first-generation (direct-collapse) black holes form a merging binary. The right illustrates a second-generation hierarchical merger: each black hole in the final merging binary was formed by the merger of two smaller black holes. [Adapted fromGerosa et al., a simultaneously published paper that also explores the problem of hierarchical mergers and reaches similar conclusions]How do black holes of this size form? One possibility is that they form in isolation from the collapse of a single massive star. In an alternative model, they are created through the hierarchical merger of smaller black holes, gradually building up to the size we observed.A team of scientists led by Maya Fishbach (University of Chicago) suggests that we may soon be able to tell whether or not black holes observed by LIGO formed hierarchically. Fishbach and collaborators argue that hierarchical formation leaves a distinctive signature on the spins of the final black holes and that as soon as we have enough merger detections from LIGO, we can use spin measurements to statistically determine if LIGO black holes were formed hierarchically.Spins from Major MergersWhen two black holes merge, both their original spins and the angular momentum of the pair contribute to the spin of the final black hole that results. Fishbach and collaborators calculate the expected distribution of these final spins assuming that

  12. A Global Spectral Study of Stellar-Mass Black Holes with Unprecedented Sensitivity

    Science.gov (United States)

    Garci, Javier

    project is a global spectroscopic studies of six bright black holes using our reflection models and new calibration tools. These synoptic studies will provide a panoramic view of black hole behavior and advance the measurement of black hole spin. The relevance of our proposed study to this NASA Research Announcement is clear because our work represents a vital use of NASA's High Energy Astrophysics Science Archive Research Center (HEASARC); conversely, it is the HEASARC that makes our work possible. In addition, our work naturally responds to the following words in the NRA: ``...the development of tools for mining the vast reservoir of information locked within [the HEASARC]...is also eligible for funding under the Astrophysics Data Analysis Program.'' Specifically we will provide new data analysis tools to the community for the study of data collected by a wide range of past, current and future X-ray missions (e.g., RXTE, Chandra, XMM-Newton, NuSTAR, Swift, NICER). Finally, we are responsive to Objective 1.6 in NASA's Strategic Plan for 2014 that calls for ``exploring the extreme conditions of the universe'' and the continuing aspiration to ``probe the origin and destiny of the universe, including the first moments of the Big Bang and the nature of black holes...''. The proposed program will be carried out over the course of three years.

  13. Area spectrum of slowly rotating black holes

    OpenAIRE

    Myung, Yun Soo

    2010-01-01

    We investigate the area spectrum for rotating black holes which are Kerr and BTZ black holes. For slowly rotating black holes, we use the Maggiore's idea combined with Kunstatter's method to derive their area spectra, which are equally spaced.

  14. New entropy formula for Kerr black holes

    OpenAIRE

    Gonzalez, Hernan; Grumiller, Daniel; Merbis, Wout; Wutte, Raphaela

    2017-01-01

    We introduce a new entropy formula for Kerr black holes inspired by recent results for 3-dimensional black holes and cosmologies with soft Heisenberg hair. We show that also Kerr-Taub-NUT black holes obey the same formula.

  15. Investigating the Infrared Properties of Candidate Blazars

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Jessica; /Southern California U. /SLAC

    2005-12-15

    Blazars are active galaxies with super-massive black holes, containing jets that accelerate plasma material and produce radiation. They are unique among other active galaxies for properties such as rapid variability and the lack of emission lines. The double-peaked spectral energy distribution (SED) found for most blazar objects suggests that synchrotron radiation and Compton scattering occurs in the jets. This study is an investigation of the infrared (IR) spectra of a selected population of blazar candidates, focusing on the IR properties of objects within the three types of blazars currently recognized by their spectral characteristics at other wavelengths. Using blazar candidates found in a recent study of the northern sky (Sowards-Emmerd et al., The Astrophysical Journal, 2005), IRAS data for 12, 25, 60, and 100 {micro}m, as well as any available data from 2MASS and EGRET, were located. The synchrotron peak of the SED of each object was expected to occur anywhere in the infrared (IR) to soft X-ray range. However, peaks were generally found to lie in the IR range, suggesting potential selection biases. An analysis of selection techniques reveals that the figure of merit used in the original survey is engineered to select objects with a Compton scattering peak luminosity occurring in the GeV range, the energy band most easily detected by the upcoming GLAST mission. Therefore, this figure of merit selection process should be used to compile a list of blazar candidates for further study in anticipation of the launch of the satellite.

  16. UNCOVERING THE NUCLEUS CANDIDATE FOR NGC 253

    Energy Technology Data Exchange (ETDEWEB)

    Günthardt, G. I.; Camperi, J. A. [Observatorio Astronómico, Universidad Nacional de Córdoba (Argentina); Agüero, M. P. [Observatorio Astronómico, Universidad Nacional de Córdoba, and CONICET (Argentina); Díaz, R. J.; Gomez, P. L.; Schirmer, M. [Gemini Observatory, AURA (United States); Bosch, G., E-mail: gunth@oac.uncor.edu, E-mail: camperi@oac.uncor.edu, E-mail: mpaguero@oac.uncor.edu, E-mail: rdiaz@gemini.edu, E-mail: pgomez@gemini.edu, E-mail: mschirmer@gemini.edu, E-mail: guille@fcaglp.unlp.edu.ar [Instituto de Astrofísica de La Plata (CONICET-UNLP) (Argentina)

    2015-11-15

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H{sub 2} rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  17. An intermediate-mass black hole in the centre of the globular cluster 47 Tucanae.

    Science.gov (United States)

    Kızıltan, Bülent; Baumgardt, Holger; Loeb, Abraham

    2017-02-08

    Intermediate-mass black holes should help us to understand the evolutionary connection between stellar-mass and super-massive black holes. However, the existence of intermediate-mass black holes is still uncertain, and their formation process is therefore unknown. It has long been suspected that black holes with masses 100 to 10,000 times that of the Sun should form and reside in dense stellar systems. Therefore, dedicated observational campaigns have targeted globular clusters for many decades, searching for signatures of these elusive objects. All candidate signatures appear radio-dim and do not have the X-ray to radio flux ratios required for accreting black holes. Based on the lack of an electromagnetic counterpart, upper limits of 2,060 and 470 solar masses have been placed on the mass of a putative black hole in 47 Tucanae (NGC 104) from radio and X-ray observations, respectively. Here we show there is evidence for a central black hole in 47 Tucanae with a mass of solar masses when the dynamical state of the globular cluster is probed with pulsars. The existence of an intermediate-mass black hole in the centre of one of the densest clusters with no detectable electromagnetic counterpart suggests that the black hole is not accreting at a sufficient rate to make it electromagnetically bright and therefore, contrary to expectations, is gas-starved. This intermediate-mass black hole might be a member of an electromagnetically invisible population of black holes that grow into supermassive black holes in galaxies.

  18. VTrans Small Culvert Inventory - Access Holes

    Data.gov (United States)

    Vermont Center for Geographic Information — Vermont Agency of Transportation Small Culvert Inventory: Access Holes. This data contains access hole locations along VTrans maintained roadways. The data was...

  19. Black Hole Grabs Starry Snack

    Science.gov (United States)

    2006-01-01

    [figure removed for brevity, see original site] Poster Version This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a 'ringside' seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end. The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light. The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.

  20. Testing the E(sub peak)-E(sub iso) Relation for GRBs Detected by Swift and Suzaku-WAM

    Science.gov (United States)

    Krimm, H. A.; Yamaoka, K.; Sugita, S.; Ohno, M.; Sakamoto, T.; Barthelmy, S. D.; Gehrels, N.; Hara, R.; Onda, K.; Sato, G.; hide

    2009-01-01

    One of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy (E(sub peak)) of the nuF(nu) spectrum and the isotropic radiated energy, E(sub iso). Since most gamma-ray bursts (GRBs) have E(sub peak) above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate E(sub peak) values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected ; one can accurately fit E(sub peak) and E(sub iso) and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of March 2009, there were 45 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 47 bursts which triggered Swift and were detected by WAM, but did not trigger. A BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters. For those bursts with spectroscopic redshifts.. we can also calculate the isotropic energy. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 86 of the bursts detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift, bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.

  1. The Swift Project Contamination Control Program: A Case Study of Balancing Cost, Schedule and Risk

    Science.gov (United States)

    Hansen, Patricia A.; Day, Diane T.; Secunda, Mark S.; Rosecrans, Glenn P.

    2004-01-01

    The Swift Observatory will be launched in early 2004 to examine the dynamic process of gamma ray burst (GRB) events. The multi-wavelength Observatory will study the GRB afterglow characteristics, which will help to answer fundamental questions about both the structure and the evolution of the universe. The Swift Observatory Contamination Control Program has been developed to aid in ensuring the success of the on-orbit performance of two of the primary instruments: the Ultraviolet and Optical Telescope (UVOT) and the X-Ray Telescope (XRT). During the design phase of the Observatory, the contamination control program evolved and trade studies were performed to assess the risk of contaminating the sensitive UVOT and XRT optics during both pre-launch testing and on-orbit operations, within the constraints of the overall program cost and schedule.

  2. A Potential Tool for Swift Fox (Vulpes velox) Conservation: Individuality of Long-Range Barking Sequences

    DEFF Research Database (Denmark)

    Darden, Safi-Kirstine Klem; Dabelsteen, Torben; Pedersen, Simon Boel

    2003-01-01

    Vocal individuality has been found in a number canid species. This natural variation can have applications in several aspects of species conservation, from behavioral studies to estimating population density or abundance. The swift fox (Vulpes velox) is a North American canid listed as endangered...... context from 20 captive individuals (3 females and 17 males) housed in large, single-pair enclosures at a swift fox breeding facility. Using a discriminant function analysis with 7 temporal and spectral variables measured on barking sequences, we were able to correctly classify 99% of sequences...... to the correct individual. The most important discriminating variable was the mean spacing of barks in a barking sequence. Potential applications of such vocal individuality are discussed....

  3. Preliminary assessment report for Camp Swift Military Reservation, Installation 48070, Bastrop County, Texas. Installation Restoration Program

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, C.B.

    1993-08-01

    This report presents the results of the preliminary assessment (PA) conducted by Argonne National Laboratory at the Texas Army National Guard property in Bastrop County, Texas. Preliminary assessments of federal facilities are being conducted to compile the information necessary for completing preremedial activities and to provide a basis for establishing corrective actions in response to releases of hazardous substances. The principal objective of the PA is to characterize the site accurately and determine the need for further action by examining site activities, quantities of hazardous substances present, and potential pathways by which contamination could affect public health and the environment. This PA satisfies, for the Camp Swift property, the requirement of the Department of Defense Installation Restoration Program (IRP). The review of both historical and current practices at the property indicated that the activities at Camp Swift include no operations considered to have an adverse impact to the environment. The recommendation, therefore, is that no further IRP action is necessary at this property.

  4. A Study of Advanced Image Processing Techniques on Experimental SWIFT Data

    Science.gov (United States)

    Trujillo, Christopher

    2017-06-01

    Accurately tracking the position of explosive-induced shock waves is a critical method for characterizing high explosive (HE) performance. The application of the shock wave image framing technique (SWIFT) has proven to be a successful diagnostic tool that utilizes ultra-high-speed imaging to capture time series images of explosively-driven shock waves propagating through transparent media. The use of common edge-detection algorithms, including Sobel, Canny, and Prewitt, tend to be susceptible to background noise and require noise reduction preprocessing that can alter the position of edge boundaries. In this paper, results produced by the implementation of advanced image-processing techniques on experimental SWIFT data show that shock wave position can accurately be detected and tracked, while also maintaining robustness to background image noise.

  5. IMATERALISASI JAMINAN BENDA DALAM BENTUK CASH COLLATERAL SEBAGAI JAMINAN PROYEK INFRA STRUKTUR MELALUI MEKANISME SWIFT

    Directory of Open Access Journals (Sweden)

    Tarsisius Murwaji

    2013-10-01

    Full Text Available The construction of infrastructure projects require large expenses. The cost for the project loan is usually derived from international banks. Legal issues, among others: we do not guarantee the legal system conducive to use in large financing; corporate body and banking institutions we considered to be of international standard, and our le-gal system is regarded as the country risk. The other hand many people of Indonesia who have collateral material, usually pure gold (precious metals that have been diimaterialization and included in the accounts of foreign banks. Such guarantees may be used as the basis of the issuance of bank guarantees and through the mechanism of Society Worldwide Interbank Financial Telecommunications (SWIFT can be used as loan collateral banks in Indonesia. Key words: bank guaranty, SWIFT, security law, international banking system

  6. Atlantic coastal plain geothermal test holes, Virginia: hole completion reports

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, L.B.; Radford, L.; Glascock, M.

    1979-03-01

    A description of the Atlantic Coastal Plain Geothermal Drilling Program and data for the following geothermal test holes drilled in Virginia are summarized: Creeds, Norfolk Naval Base, Langley Air Force Base, Wattsville, Withams, and Atlantic.

  7. Unveiling the edge of time black holes, white holes, wormholes

    CERN Document Server

    Gribbin, John

    1992-01-01

    Acclaimed science writer John Gribbin recounts dramatic stories that have led scientists to believe black holes and their more mysterious kin are not only real, but might actually provide a passage to other universes and travel through time.

  8. Quantum mechanics of black holes.

    Science.gov (United States)

    Witten, Edward

    2012-08-03

    The popular conception of black holes reflects the behavior of the massive black holes found by astronomers and described by classical general relativity. These objects swallow up whatever comes near and emit nothing. Physicists who have tried to understand the behavior of black holes from a quantum mechanical point of view, however, have arrived at quite a different picture. The difference is analogous to the difference between thermodynamics and statistical mechanics. The thermodynamic description is a good approximation for a macroscopic system, but statistical mechanics describes what one will see if one looks more closely.

  9. Orbital resonances around black holes.

    Science.gov (United States)

    Brink, Jeandrew; Geyer, Marisa; Hinderer, Tanja

    2015-02-27

    We compute the length and time scales associated with resonant orbits around Kerr black holes for all orbital and spin parameters. Resonance-induced effects are potentially observable when the Event Horizon Telescope resolves the inner structure of Sgr A*, when space-based gravitational wave detectors record phase shifts in the waveform during the resonant passage of a compact object spiraling into the black hole, or in the frequencies of quasiperiodic oscillations for accreting black holes. The onset of geodesic chaos for non-Kerr spacetimes should occur at the resonance locations quantified here.

  10. Black holes and Higgs stability

    CERN Document Server

    Tetradis, Nikolaos

    2016-09-20

    We study the effect of primordial black holes on the classical rate of nucleation of AdS regions within the standard electroweak vacuum. We find that the energy barrier for transitions to the new vacuum, which characterizes the exponential suppression of the nucleation rate, can be reduced significantly in the black-hole background. A precise analysis is required in order to determine whether the the existence of primordial black holes is compatible with the form of the Higgs potential at high temperature or density in the Standard Model or its extensions.

  11. Naturally Occurring Asbestos in Washington State: Swift Creek at the Intersection of Science, Law, and Risk Perception

    Science.gov (United States)

    Melious, J. O.

    2012-12-01

    In the northwestern corner of Washington state, a large landslide on Sumas Mountain deposits more than 100,000 cubic yards of soil containing asbestos fibers and heavy metals into Swift Creek every year. Engineers predict that asbestos-laden soils will slide into Swift Creek for at least the next 400 years. Swift Creek joins the Sumas River, which crosses the border into Canada, serving as an international delivery system for asbestos-laden soils. When the rivers flood, as happens regularly, they deliver asbestos into field, yards, and basements. The tools available to address the Swift Creek situation are at odds with the scope and nature of the problem. Asbestos regulation primarily addresses occupational settings, where exposures can be estimated. Hazardous waste regulation primarily addresses liability for abandoned waste products from human activities. Health and environmental issues relating to naturally occurring asbestos (NOA) are fundamentally different from either regulatory scheme. Liability is not a logical lever for a naturally occurring substance, the existence of which is nobody's fault, and exposures to NOA in the environment do not necessarily resemble occupational exposures. The gaps and flaws in the legal regime exacerbate the uncertainties created by uncertainties in the science. Once it is assumed that no level of exposure is safe, legal requirements adopted in very different contexts foreclose the options for addressing the Swift Creek problem. This presentation will outline the applicable laws and how they intersect with issues of risk perception, uncertainty and politics in efforts to address the Swift Creek NOA site.

  12. Amplitude equations for the generalised Swift-Hohenberg equation with noise

    OpenAIRE

    Klepel, Konrad

    2015-01-01

    For the generalised Swift-Hohenberg equation with added noise acting uniformly on the system, amplitude equations for a bounded 1D domain and the whole real line are derived. Because of the inherent separation of timescales a dominant sine-like pattern evolves that is governed by a stochastic differential equation called the amplitude equation of the system. The dominant frequencies are not directly forced by the noise but through the nonlinearity composed of a stable cubic and an unstable qu...

  13. Effect of swift heavy ion irradiation on surface resistance of DyBa 2 ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 58; Issue 5-6. Effect of swift heavy ion irradiation on surface resistance of DyBa2Cu3O7- thin films at microwave frequencies. Ujwala Ail Tamalika Banerjee A R Bhangale D Kanjilal R Pinto. Physics of Vortex State Volume 58 Issue 5-6 May-June 2002 pp 959-963 ...

  14. A FTIR characterization of a haemocompatible material obtained by swift heavy ion radiation grafting

    Energy Technology Data Exchange (ETDEWEB)

    Dapoz, S.; Betz, N.; Le Moel, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche sur l`Etat Condense, les Atomes et les Molecules

    1996-01-01

    In order to prepare materials destined to be used as vascular prothesis, a radiation grafting of styrene, induced by swift heavy ions in polyvinylidene fluoride films, was performed. A substitution of the grafted polystyrene with sulfonate and aspartic acid sulfamide groups, which confers to the polymer anticoagulant properties, was achieved. The material was characterized by Fourier Transform Infrared spectroscopy at each step of the synthesis. (authors). 5 refs., 2 figs.

  15. Efficiency of lift production in flapping and gliding flight of swifts.

    Directory of Open Access Journals (Sweden)

    Per Henningsson

    Full Text Available Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord and/or twist from root to tip (reducing local angle of attack. We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding species, the common swift, by measuring the wakes generated by two birds, one in gliding and one in flapping flight in a wind tunnel. We calculated span efficiency, the efficiency of lift production, and found that the flapping swift had consistently higher span efficiency than the gliding swift. This supports our hypothesis and suggests that even though swifts have been shown previously to increase their lift-to-drag ratio substantially when gliding, the wing morphology is tuned to be more aerodynamically efficient in generating lift during flapping. Since body drag can be assumed to be similar for both flapping and gliding, it follows that the higher total drag in flapping flight compared with gliding flight is primarily a consequence of an increase in wing profile drag due to the flapping motion, exceeding the reduction in induced drag.

  16. Obscuring Torus Geometry from the NuSTAR Survey of Swift/BAT AGN

    Science.gov (United States)

    Balokovic, Mislav; Harrison, Fiona; NuSTAR

    2016-06-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the spectral window above 10 keV with unprecedented spatial resolution and two orders of magnitude better sensitivity than any other instrument operating in that energy range. As a part of its long-term extragalactic program NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT). I will present spectroscopic results based on NuSTAR and Swift observations of ~150 Swift/BAT AGN surveyed in the first three years of NuSTAR operation. This sample forms an atlas of the highest quality hard X-ray spectra available to date for a large number of AGN, providing unprecedented insight into the variety AGN spectra in the hard X-ray band. In addition to phenomenology, which is an essential ingredient of Cosmic X-ray Background studies, it is possible to use new fitting models to directly probe the geometry of the toroidal obscurer (torus). Its main spectral features lie within the NuSTAR bandpass, making it possible to test the common assumption that a similar Compton-thick torus exists around essentially every Seyfert-type AGN. I will discuss torus geometry constraints based on the X-ray spectra in relation to those from other wavelengths, the effects on interpretation of high-redshift AGN observations, and the limitations of the current results.

  17. Knihovna pro genetické programování v jazyce Swift

    OpenAIRE

    Mánek, Petr

    2016-01-01

    Imitating the process of natural selection, evolutionary algorithms have shown to be efficient search techniques for optimization and machine learning in poorly understood and irregular spaces. In this thesis, we implement a library containing essential implementation of such algorithms in recently unveiled programming language Swift. The result is a lightweight framework compatible with Linux- based computing clusters as well as mobile devices. Such wide range of supported platforms allows f...

  18. Mixing induced by swift heavy ion irradiation at Fe/Si interface

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The present work deals with the mixing of metal and silicon by swift heavy ions in high-energy range. Threshold value for the defect creation in metal Fe calculated was found to be ~ 40 keV/nm. A thin film of Fe (10 nm) was deposited on Si (100) at a pressure of 4 × 10–8 Torr and was irradiated with 95 MeV Au ions ...

  19. Fermi and Swift as supernova alarms: Alert, localization, and diagnosis of future Galactic Type Ia explosions

    Science.gov (United States)

    Wang, Xilu; Fields, Brian D.; Lien, Amy Y.

    2017-01-01

    A Galactic SNIa event could go entirely unnoticed due to the large optical and near-IR extinction in the Milky Way plane, low radio and X-ray luminosities, and a weak neutrino signal. But the recent SN2014J confirms that Type Ia supernovae emit nuclear γ- ray lines, from the 56Ni → 56Co → 56Fe radioactive decay. The energy released in these decays powers the SNIa UVOIR light curve at times after ~1 week, leading to an exponential decline. Importantly for Swift and Fermi, these decays are accompanied by γ-ray line emission, with distinct series of lines for both the 56Ni and 56Co decays, spanning 158 keV to 2.6 MeV. These lines are squarely within the Fermi/GBM energy range, and the 56Ni 158 keV line is detectable by Swift/BAT. The Galaxy is optically thin to γ-rays, so the supernova line flux will suffer negligible extinction. Both GBM and BAT have continuous and nearly all-sky coverage. Thus GBM and BAT are ideal Galactic SNIa monitors and early warning systems. We will illustrate expected GBM and BAT light curves and spectra, based on our model for SNIa γ-ray emission and transfer. We show that the supernova signal emerges as distinct from the GBM background within days after the explosion in the SN2014J shell model. Therefore, if a Galactic SNIa were to explode, there are two possibilities of confirming and sounding the alert: 1) Swift/BAT discovers the SNIa first and localizes it within arcminutes; 2) Fermi/GBM finds the SNIa first and localizes it to within ~1 degree, using the Earth occultation technique, followed up by BAT to localize it within arcminutes. After the alert of either BAT or GBM, Swift localizes it to take spectra in optical, UV, soft and hard X-rays simultaneously with both XRT and UVOT instruments.

  20. Heating solar coronal holes

    Science.gov (United States)

    Parker, E. N.

    1991-01-01

    It has been shown that the coronal hole, and the associated high-speed stream in the solar wind, are powered by a heat input of the order of 500,000 ergs/sq cm s, with most of the heat injected in the first 1-2 solar radii, and perhaps 100,000 ergs/sq cm s introduced at distances of several solar radii to provide the high speed of the issuing solar wind. The traditional view has been that this energy is obtained from Alfven waves generated in the subphotospheric convection, which dissipate as they propagate outward, converting the wave energy into heat. This paper reviews the generation of waves and the known wave dissipation mechanisms, to show that the necessary Alfven waves are not produced under the conditions presently understood to exist in the sun, nor would such waves dissipate significantly in the first 1-2 solar radii if they existed. Wave dissipation occurs only over distances of the order of 5 solar radii or more.

  1. Bottom hole blowout preventer

    Energy Technology Data Exchange (ETDEWEB)

    Lineham, D.H.

    1991-04-24

    An automatically controlled ball-valve type bottom-hole blowout preventer is provided for use in drilling oil or gas wells. The blowout preventer of the invention operates under normal drilling conditions in a fully open position with an unrestricted bore. This condition is maintained by a combination of spring and mud flow pressure acting against the upper surfaces of the valve. In the event of a well kick or blowout, pressures from gas or fluid volumes acting against the lower surfaces of the valve force it into the fully closed position. A system of ports and check valves within the blowout preventer forces hydraulic fluid from one chamber to another. The metering effect of these ports determines the rate of closure of the valve, thereby allowing normal running and pulling of the drill string or tubing, without interference to pipe fill-up or drainage, from valve closure. The blowout preventer is placed in a subassembly that is an integral part of the drill string and can be incorporated in a string in any location. 3 figs.

  2. Black hole meiosis

    Science.gov (United States)

    van Herck, Walter; Wyder, Thomas

    2010-04-01

    The enumeration of BPS bound states in string theory needs refinement. Studying partition functions of particles made from D-branes wrapped on algebraic Calabi-Yau 3-folds, and classifying states using split attractor flow trees, we extend the method for computing a refined BPS index, [1]. For certain D-particles, a finite number of microstates, namely polar states, exclusively realized as bound states, determine an entire partition function (elliptic genus). This underlines their crucial importance: one might call them the ‘chromosomes’ of a D-particle or a black hole. As polar states also can be affected by our refinement, previous predictions on elliptic genera are modified. This can be metaphorically interpreted as ‘crossing-over in the meiosis of a D-particle’. Our results improve on [2], provide non-trivial evidence for a strong split attractor flow tree conjecture, and thus suggest that we indeed exhaust the BPS spectrum. In the D-brane description of a bound state, the necessity for refinement results from the fact that tachyonic strings split up constituent states into ‘generic’ and ‘special’ states. These are enumerated separately by topological invariants, which turn out to be partitions of Donaldson-Thomas invariants. As modular predictions provide a check on many of our results, we have compelling evidence that our computations are correct.

  3. Erratic Black Hole Regulates Itself

    Science.gov (United States)

    2009-03-01

    New results from NASA's Chandra X-ray Observatory have made a major advance in explaining how a special class of black holes may shut off the high-speed jets they produce. These results suggest that these black holes have a mechanism for regulating the rate at which they grow. Black holes come in many sizes: the supermassive ones, including those in quasars, which weigh in at millions to billions of times the mass of the Sun, and the much smaller stellar-mass black holes which have measured masses in the range of about 7 to 25 times the Sun's mass. Some stellar-mass black holes launch powerful jets of particles and radiation, like seen in quasars, and are called "micro-quasars". The new study looks at a famous micro-quasar in our own Galaxy, and regions close to its event horizon, or point of no return. This system, GRS 1915+105 (GRS 1915 for short), contains a black hole about 14 times the mass of the Sun that is feeding off material from a nearby companion star. As the material swirls toward the black hole, an accretion disk forms. This system shows remarkably unpredictable and complicated variability ranging from timescales of seconds to months, including 14 different patterns of variation. These variations are caused by a poorly understood connection between the disk and the radio jet seen in GRS 1915. Chandra, with its spectrograph, has observed GRS 1915 eleven times since its launch in 1999. These studies reveal that the jet in GRS 1915 may be periodically choked off when a hot wind, seen in X-rays, is driven off the accretion disk around the black hole. The wind is believed to shut down the jet by depriving it of matter that would have otherwise fueled it. Conversely, once the wind dies down, the jet can re-emerge. "We think the jet and wind around this black hole are in a sort of tug of war," said Joseph Neilsen, Harvard graduate student and lead author of the paper appearing in the journal Nature. "Sometimes one is winning and then, for reasons we don

  4. Single ion induced surface nanostructures: a comparison between slow highly charged and swift heavy ions.

    Science.gov (United States)

    Aumayr, Friedrich; Facsko, Stefan; El-Said, Ayman S; Trautmann, Christina; Schleberger, Marika

    2011-10-05

    This topical review focuses on recent advances in the understanding of the formation of surface nanostructures, an intriguing phenomenon in ion-surface interaction due to the impact of individual ions. In many solid targets, swift heavy ions produce narrow cylindrical tracks accompanied by the formation of a surface nanostructure. More recently, a similar nanometric surface effect has been revealed for the impact of individual, very slow but highly charged ions. While swift ions transfer their large kinetic energy to the target via ionization and electronic excitation processes (electronic stopping), slow highly charged ions produce surface structures due to potential energy deposited at the top surface layers. Despite the differences in primary excitation, the similarity between the nanostructures is striking and strongly points to a common mechanism related to the energy transfer from the electronic to the lattice system of the target. A comparison of surface structures induced by swift heavy ions and slow highly charged ions provides a valuable insight to better understand the formation mechanisms. © 2011 IOP Publishing Ltd

  5. Afterglow Population Studies from Swift Follow-Up Observations of Fermi LAT GRBs

    Science.gov (United States)

    Racusin, Judith L.; Oates, S. R.; McEnery, J.; Vasileiou, V.; Troja, E.; Gehrels, N.

    2010-01-01

    The small population of Fermi LAT detected GRBs discovered over the last year has been providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 5 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into other components of GRB emission structure. We explore the new ability to utilize both of these observatories to study the same GRBs over 10 orders of magnitude in energy, although not always concurrently. Almost all LAT GRBs that have been followed-up by Swift within 1-day have been clearly detected and carefully observed. We will present the context of the lower-energy afterglows of this special subset of GRBs that has > 100 MeV emission compared to the hundreds in the Swift database that may or may not have been observed by LAT, and theorize upon the relationship between these properties and the origin of the high energy gamma-ray emission.

  6. The HEASARC Swift Gamma-Ray Burst Archive: The Pipeline and the Catalog

    Science.gov (United States)

    Donato, Davide; Angelini, Lorella; Padgett, C.A.; Reichard, T.; Gehrels, Neil; Marshall, Francis E.; Sakamoto, Takanori

    2012-01-01

    Since its launch in late 2004, the Swift satellite triggered or observed an average of one gamma-ray burst (GRB) every 3 days, for a total of 771 GRBs by 2012 January. Here, we report the development of a pipeline that semi automatically performs the data-reduction and data-analysis processes for the three instruments on board Swift (BAT, XRT, UVOT). The pipeline is written in Perl, and it uses only HEAsoft tools and can be used to perform the analysis of a majority of the point-like objects (e.g., GRBs, active galactic nuclei, pulsars) observed by Swift. We run the pipeline on the GRBs, and we present a database containing the screened data, the output products, and the results of our ongoing analysis. Furthermore, we created a catalog summarizing some GRB information, collected either by running the pipeline or from the literature. The Perl script, the database, and the catalog are available for downloading and querying at the HEASARC Web site.

  7. Rotationally Powered Magnetar Nebula around Swift J1834.9-0846

    Science.gov (United States)

    Torres, Diego F.

    2017-01-01

    A wind nebula generating extended X-ray emission was recently detected surrounding Swift J1834.9-0846. This is the first magnetar for which such a wind nebula was found. Here, we investigate whether there is a plausible scenario where the pulsar wind nebula (PWN) can be sustained without the need of advocating for additional sources of energy other than rotational. We do this by using a detailed radiative and dynamical code that studies the evolution of the nebula and its particle population in time. We find that such a scenario indeed exists: Swift J1834.9-0846's nebula can be explained as being rotationally powered, as all other known PWNe are, if it is currently being compressed by the environment. The latter introduces several effects, the most important of which is the appearance of adiabatic heating, being increasingly dominant over the escape of particles as reverberation goes by. The need of reverberation naturally explains why this is the only magnetar nebula detected and provides estimates for Swift 1834.9-0846's age.

  8. FY17 Accomplishments - Testing Facilities and Capabilities at SWiFT, SNL

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Jonathan Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    The Scaled Wind Farm Technologies (SWiFT) facility operated by Sandia National Laboratories (SNL) has, in support of the Atmosphere to electrons (A2e) research program, acquired measurements of wind turbine wake dynamics under various atmospheric conditions and while interacting with a downstream wind turbine. SNL researchers, in collaboration with National Renewable Energy Laboratory (NREL) researchers, installed a customized LIDAR system created by the Technical University of Denmark (DTU) in one of the SWiFT wind turbines (Figure 1) and operated that turbine with intentional yaw-versus-winddirection misalignment to study the behavior of the turbine wake under numerous combinations of atmospheric conditions and turbine yaw offsets. The DTU-customized LIDAR provided detailed measurements of the wake’s shape and location at many distances downwind of the turbine (Figure 2). These measurements will benefit wind energy researchers looking to understand wind turbine wake behavior and improve modeling and simulation of wake dynamics, including the “wake steering” affect that is observed when turbine yaw offset is controlled. During the test campaign, two SWiFT wind turbines were operated at the same time to observe the influence of the turbines on each other as the wake of the upwind turbine was observed sweeping over and interacting with the downwind turbine.

  9. A Social Wellbeing in Fisheries Tool (SWIFT to Help Improve Fisheries Performance

    Directory of Open Access Journals (Sweden)

    Tracy Van Holt

    2016-07-01

    Full Text Available We report on a rapid and practical method to assess social dimensions of performance in small-scale and industrial fisheries globally (Social Wellbeing in Fisheries Tool (SWIFT. SWIFT incorporates aspects of security (fairness and stability of earnings, benefits of employment to local fishing communities, worker protection, and personal safety and health in communities associated with fisheries; flexibility (including opportunity for economic advancement; and the fishery’s social viability (including whether the fishery is recruiting new harvesters and diverse age classes of workers, whether women’s participation and leadership in global production networks are on an upward trajectory.. We build on resilience research by conceptualizing wellbeing in terms of security, flexibility, and viability, and assessing wellbeing at individual, community, and system levels. SWIFT makes social performance measures more broadly accessible to global production networks, incorporates an everyday understanding of wellbeing for people involved in the seafood industry, and helps put social sustainability into measurable terms that are relevant for businesses.

  10. Galactic Black Holes in the Hard State: A Multi-Wavelength View of Accretion and Ejection

    Science.gov (United States)

    Kalemci; Tomsick, John A.; Migliari; Corbel; Markoff

    2010-01-01

    The canonical hard state is associated with emission from all three fundamental accretion components: the accretion disk, the hot accretion disk corona and the jet. On top of these, the hard state also hosts very rich temporal variability properties (low frequency QPOs in the PDS, time lags, long time scale evolution). Our group has been working on the major questions of the hard state both observationally (with mult i-wavelength campaigns using RXTE, Swift, Suzaku, Spitzer, VLA, ATCA, SMARTS) and theoretically (through jet models that can fit entire SEDs). Through spectral and temporal analysis we seek to determine the geometry of accretion components, and relate the geometry to the formation and emission from a jet. In this presentation I will review the recent contributions of our group to the field, including the Swift results on the disk geometry at low accretion rates, the jet model fits to the hard state SEDs (including Spitzer data) of GRO J1655-40, and the final results on the evolution of spectral (including X-ray, radio and infrared) and temporal properties of elected black holes in the hard states. I will also talk about impact of ASTROSAT to the science objective of our group.

  11. The physics of black holes

    CERN Document Server

    Susskind, Leonard

    1997-01-01

    I will describe profound revolution in our understanding of black holes and their relation to quantum mechanics that has occured over the last few years as a result of a deeper understanding of string theory.

  12. Probing Primordial Black Hole Dark Matter with Gravitational Waves.

    Science.gov (United States)

    Kovetz, Ely D

    2017-09-29

    Primordial black holes (PBHs) have long been suggested as a candidate for making up some or all of the dark matter in the Universe. Most of the theoretically possible mass range for PBH dark matter has been ruled out with various null observations of expected signatures of their interaction with standard astrophysical objects. However, current constraints are significantly less robust in the 20  M_{⊙}≲M_{PBH}≲100  M_{⊙} mass window, which has received much attention recently, following the detection of merging black holes with estimated masses of ∼30  M_{⊙} by LIGO and the suggestion that these could be black holes formed in the early Universe. We consider the potential of advanced LIGO (aLIGO) operating at design sensitivity to probe this mass range by looking for peaks in the mass spectrum of detected events. To quantify the background, which is due to black holes that are formed from dying stars, we model the shape of the stellar-black-hole mass function and calibrate its amplitude to match the O1 results. Adopting very conservative assumptions about the PBH and stellar-black-hole merger rates, we show that ∼5  yr of aLIGO data can be used to detect a contribution of >20  M_{⊙} PBHs to dark matter down to f_{PBH}99.9% confidence level. Combined with other probes that already suggest tension with f_{PBH}=1, the obtainable independent limits from aLIGO will thus enable a firm test of the scenario that PBHs make up all of dark matter.

  13. Hole dephasing caused by hole-hole interaction in a multilayered black phosphorus.

    Science.gov (United States)

    Li, Lijun; Khan, Muhammad Atif; Lee, Yoontae; Lee, Inyeal; Yun, Sun Jin; Youn, Doo-Hyeb; Kim, Gil-Ho

    2017-11-01

    We study the magnetotransport of holes in a multilayered black phosphorus in a temperature range of 1.9 to 21.5 K. We observed a negative magnetoresistance at magnetic fields up to 1.5 T. This negative magetoresistance was analyzed by weak localization theory in diffusive regime. At the lowest temperature and the highest carrier density we found a phase coherence length of 48 nm. The linear temperature dependence of the dephasing rate shows that the hole-hole scattering processes with small energy transfer are the dominant contribution in breaking the carrier phase coherence.

  14. Jetted tidal disruptions of stars as a flag of intermediate mass black holes at high redshifts

    Science.gov (United States)

    Fialkov, Anastasia; Loeb, Abraham

    2017-11-01

    Tidal disruption events (TDEs) of stars by single or binary supermassive black holes (SMBHs) brighten galactic nuclei and reveal a population of otherwise dormant black holes. Adopting event rates from the literature, we aim to establish general trends in the redshift evolution of the TDE number counts and their observable signals. We pay particular attention to (I) jetted TDEs whose luminosity is boosted by relativistic beaming and (II) TDEs around binary black holes. We show that the brightest (jetted) TDEs are expected to be produced by massive black hole binaries if the occupancy of intermediate mass black holes (IMBHs) in low-mass galaxies is high. The same binary population will also provide gravitational wave sources for the evolved Laser Interferometer Space Antenna. In addition, we find that the shape of the X-ray luminosity function of TDEs strongly depends on the occupancy of IMBHs and could be used to constrain scenarios of SMBH formation. Finally, we make predictions for the expected number of TDEs observed by future X-ray telescopes finding that a 50 times more sensitive instrument than the Burst Alert Telescope (BAT) on board the Swift satellite is expected to trigger ˜10 times more events than BAT, while 6-20 TDEs are expected in each deep field observed by a telescope 50 times more sensitive than the Chandra X-ray Observatory if the occupation fraction of IMBHs is high. Because of their long decay times, high-redshift TDEs can be mistaken for fixed point sources in deep field surveys and targeted observations of the same deep field with year-long intervals could reveal TDEs.

  15. The 2002 Antarctic Ozone Hole

    Science.gov (United States)

    Newman, P. A.; Nash, E. R.; Douglass, A. R.; Kawa, S. R.

    2003-01-01

    Since 1979, the ozone hole has grown from near zero size to over 24 Million km2. This area is most strongly controlled by levels of inorganic chlorine and bromine oncentrations. In addition, dynamical variations modulate the size of the ozone hole by either cooling or warming the polar vortex collar region. We will review the size observations, the size trends, and the interannual variability of the size. Using a simple trajectory model, we will demonstrate the sensitivity of the ozone hole to dynamical forcing, and we will use these observations to discuss the size of the ozone hole during the 2002 Austral spring. We will further show how the Cly decreases in the stratosphere will cause the ozone hole to decrease by 1-1.5% per year. We will also show results from a 3-D chemical transport model (CTM) that has been continuously run since 1999. These CTM results directly show how strong dynamics acts to reduce the size of the ozone hole.

  16. Black Hole Spin Measurement Uncertainty

    Science.gov (United States)

    Salvesen, Greg; Begelman, Mitchell C.

    2018-01-01

    Angular momentum, or spin, is one of only two fundamental properties of astrophysical black holes, and measuring its value has numerous applications. For instance, obtaining reliable spin measurements could constrain the growth history of supermassive black holes and reveal whether relativistic jets are powered by tapping into the black hole spin reservoir. The two well-established techniques for measuring black hole spin can both be applied to X-ray binaries, but are in disagreement for cases of non-maximal spin. This discrepancy must be resolved if either technique is to be deemed robust. We show that the technique based on disc continuum fitting is sensitive to uncertainties regarding the disc atmosphere, which are observationally unconstrained. By incorporating reasonable uncertainties into black hole spin probability density functions, we demonstrate that the spin measured by disc continuum fitting can become highly uncertain. Future work toward understanding how the observed disc continuum is altered by atmospheric physics, particularly magnetic fields, will further strengthen black hole spin measurement techniques.

  17. Accretion, primordial black holes and standard cosmology

    Indian Academy of Sciences (India)

    Primordial black holes evaporate due to Hawking radiation. We find that the evaporation times of primordial black holes increase when accretion of radiation is included. Thus, depending on accretion efficiency, more primordial black holes are existing today, which strengthens the conjecture that the primordial black holes ...

  18. Formation and Coalescence of Electron Solitary Holes

    DEFF Research Database (Denmark)

    Saeki, K.; Michelsen, Poul; Pécseli, H. L.

    1979-01-01

    Electron solitary holes were observed in a magnetized collisionless plasma. These holes were identified as Bernstein-Green-Kruskal equilibria, thus being purely kinetic phenomena. The electron hole does not damp even though its velocity is close to the electron thermal velocity. Two holes attract...

  19. Electoral Systems and Candidate Selection

    NARCIS (Netherlands)

    Hazan, Reuven Y.; Voerman, Gerrit

    Electoral systems at the national level and candidate selection methods at the party level are connected, maybe not causally but they do influence each other. More precisely, the electoral system constrains and conditions the parties' menu of choices concerning candidate selection. Moreover, in

  20. 2009 Elections: The Candidates Statements

    Science.gov (United States)

    TechTrends: Linking Research and Practice to Improve Learning, 2009

    2009-01-01

    This article presents the candidates for the 2009 Association for Educational Communications and Technology (AECT) election and their statements. The candidates are: (1) Andy Gibbons (President-Elect); (2) Barbara B. Lockee (President-Elect); (3) Mary Jean Bishop (At-Large Representative); and (4) Deepak Subramony (At-Large Representative). In…

  1. On Estimating the Total Number of Intermediate Mass Black Holes

    Science.gov (United States)

    Caputo, Daniel P.; de Vries, Nathan; Patruno, Alessandro; Portegies Zwart, Simon

    2017-07-01

    Black holes have been detected with masses less than 102 and greater than 105 M⊙, but black holes with masses in the intermediate range are conspicuously absent. However, recent estimates of the mass of HLX-1, currently the strongest intermediate mass black hole (IMBH) candidate, suggest an approximate mass of 104 M⊙, and recent estimates of the mass of M82 X-1 suggest a mass of 4 × 102, placing them within the missing black hole range. This raises the question of whether these are unique objects or if many more of these objects should be expected. We estimate the number of HLX-1 like IMBHs expected within the distance of 100 Mpc to be within an order of ≈106, or ≈102 IMBHs within a galaxy, and about two orders of magnitude more when considering less massive IMBHs using M82 X-1 as a prototype. In the process of estimating this value, we determine the form of the mass function within the sphere of influence of a newly formed IMBH to be a power law with a slope of -1.83. Furthermore, we find that we are only able to fit both the period and luminosity of HLX-1 with a stellar companion with a mass between ≈10 and 11 M⊙, a result that is fairly robust to the mass of the IMBH between 103 and 105 M⊙.

  2. Programovací jazyk Swift a jeho zařazení do výuky podle metodiky Architecture First

    OpenAIRE

    Matějka, Martin

    2017-01-01

    The main topic of this bachelors thesis is transfer of frameworks into the Swift programming language for the iOS platform, which are used in the first phases of teaching of object programming in the Java programming language. The first part are explained basics of organization the Swift code and some programming designs the Swift language. The second part analyses the Architecture First methodology because this methodology is the main idea why these frameworks were programmed. The third part...

  3. Rethinking Black Hole Accretion Discs

    Science.gov (United States)

    Salvesen, Greg

    Accretion discs are staples of astrophysics. Tapping into the gravitational potential energy of the accreting material, these discs are highly efficient machines that produce copious radiation and extreme outflows. While interesting in their own right, accretion discs also act as tools to study black holes and directly influence the properties of the Universe. Black hole X-ray binaries are fantastic natural laboratories for studying accretion disc physics and black hole phenomena. Among many of the curious behaviors exhibited by these systems are black hole state transitions -- complicated cycles of dramatic brightening and dimming. Using X-ray observations with high temporal cadence, we show that the evolution of the accretion disc spectrum during black hole state transitions can be described by a variable disc atmospheric structure without invoking a radially truncated disc geometry. The accretion disc spectrum can be a powerful diagnostic for measuring black hole spin if the effects of the disc atmosphere on the emergent spectrum are well-understood; however, properties of the disc atmosphere are largely unconstrained. Using statistical methods, we decompose this black hole spin measurement technique and show that modest uncertainties regarding the disc atmosphere can lead to erroneous spin measurements. The vertical structure of the disc is difficult to constrain due to our ignorance of the contribution to hydrostatic balance by magnetic fields, which are fundamental to the accretion process. Observations of black hole X-ray binaries and the accretion environments near supermassive black holes provide mounting evidence for strong magnetization. Performing numerical simulations of accretion discs in the shearing box approximation, we impose a net vertical magnetic flux that allows us to effectively control the level of disc magnetization. We study how dynamo activity and the properties of turbulence driven by the magnetorotational instability depend on the

  4. Regular black hole in three dimensions

    OpenAIRE

    Myung, Yun Soo; Yoon, Myungseok

    2008-01-01

    We find a new black hole in three dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare thermodynamics of this black hole with that of non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy.

  5. Is the Kerr black hole a super accelerator?

    Science.gov (United States)

    Krasnikov, S.; Skvortsova, M. V.

    2018-02-01

    A number of long-standing puzzles, such as the origin of extreme-energy cosmic rays, could perhaps be solved if we found a mechanism for effectively transferring energy from black holes to particles and, correspondingly, accelerating the latter to (unboundedly, as long as we neglect the back reaction) large velocities. As of today the only such candidate mechanism in the case of the nonextreme Kerr black hole is colliding a particle that freely falls from infinity with a particle whose trajectory is subject to some special requirements to fulfil which it has to be suitably corrected by auxiliary collisions. In the present paper we prove that—at least when the relevant particles move in the equatorial plane and experience a single correcting collision—this mechanism does not work too. The energy of the final collision becomes unboundedly high only when the energies of the incoming particles do.

  6. Programovací jazyk Swift a účelnost jeho zařazení do výuky

    OpenAIRE

    Dmitricheva, Valeriya

    2015-01-01

    This thesis deals with the Swift programming language and suitability of its inclussion in education. Swift is multi paradigm programming language, because it contains elements of object-oriented programming. But it is possible to try some elements from functional progamming. Apple introduced the Swift to the public during WWDC June 2 2014 and currently Swift is used in Mac OS X and iOS platform. This thesis is diveded into five parts. The first one describes the history of language and its i...

  7. Exact time-dependent states for throat quantized toroidal AdS black holes

    Science.gov (United States)

    Maeda, Hideki; Kunstatter, Gabor

    2017-11-01

    We investigate exact nonstationary quantum states of vacuum toroidal black holes with a negative cosmological constant in arbitrary dimensions using the framework of throat quantization pioneered by Louko and Mäkelä for Schwarzschild black holes. The system is equivalent to a harmonic oscillator on the half line, in which the central singularity is resolved quantum mechanically by imposing suitable boundary conditions that preserve unitarity. We identify two suitable families of exact time-dependent wave functions with Dirichlet or Neumann boundary conditions at the location of the classical singularity. We find that for highly nonstationary states of large-mass black holes, quantum fluctuations are not negligible in one family, while they are greatly suppressed in the other. The latter, therefore, may provide candidates for describing the dynamics of semiclassical black holes.

  8. EXIST: Surveying Black Holes from the Early Universe to Local Galaxies

    Science.gov (United States)

    Grindlay, Jonathan

    2009-05-01

    The Energetic X-ray Imaging Survey Telescope (EXIST) is proposed to survey the Universe for black holes on all scales and is a leading candidate to be the Black Hole Finder Probe with three primary science goals: 1. Detect and study cosmic gamma-ray bursts (GRBs) at high redshift to study stellar mass black hole formation and the epoch of re-ionization in the Early Universe. 2. Conduct an unbiased hard X-ray survey for supermassive black holes in galactic nuclei to measure the fraction of those that are obscured and/or dormant to constrain the accretion luminosity of the Universe; and 3. Study high energy transients, from stars to SMBHs, synoptic with ground and space temporal surveys. EXIST would carry 3 instruments: a wide-field (90^ox70^o) high energy (5-600 keV) telescope (HET) to yield EXIST would serve a broad community of guest investigators following a proposed launch in 2017.

  9. Optical Studies of 13 Hard X-Ray Selected Cataclysmic Binaries from the Swift-BAT Survey

    Science.gov (United States)

    Halpern, Jules P.; Thorstensen, John R.

    2015-12-01

    From a set of 13 cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of 11, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4 hr. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less secure. Coherent pulsations are detected from two objects, Swift J0503.7-2819 (975 s) and Swift J0614.0+1709 (1412 s and 1530 s, spin and beat periods, respectively), indicating that they are probable intermediate polars (DQ Herculis stars). For two other stars, longer spin periods are tentatively suggested. We also present the discovery of a 2.00 hr X-ray modulation from RX J2015.6+3711, possibly a contributor to Swift J2015.9+3715, and likely a polar. Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

  10. Charge carrier holes and Majorana fermions

    Science.gov (United States)

    Liang, Jingcheng; Lyanda-Geller, Yuli

    2017-05-01

    Understanding Luttinger holes in low dimensions is crucial for numerous spin-dependent phenomena and nanotechnology. In particular, hole quantum wires that are proximity coupled to a superconductor is a promising system for the observation of Majorana fermions. Earlier treatments of confined Luttinger holes ignored a mutual transformation of heavy and light holes at the heteroboundaries. We derive the effective hole Hamiltonian in the ground state. The mutual transformation of holes is crucial for Zeeman and spin-orbit coupling, and results in several spin-orbit terms linear in momentum in hole quantum wires. We discuss the criterion for realizing Majorana modes in charge carrier hole systems. GaAs or InSb hole wires shall exhibit stronger topological superconducting pairing, and provide additional opportunities for its control compared to InSb electron systems.

  11. Forming Stars Near Our Supermassive Black Hole

    Science.gov (United States)

    Kohler, Susanna

    2018-01-01

    Is it possible to form stars in the immediate vicinity of the hostile supermassive black hole at the center of our galaxy? New evidence suggests that nature has found a way.Infrared view of the central 300 light-years of our galaxy. [Hubble: NASA/ESA/Q.D. Wang; Spitzer: NASA/JPL/S. Stolovy]Too Hostile for Stellar Birth?Around Sgr A*, the supermassive black hole lurking at the Milky Ways center, lies a population of 200 massive, young, bright stars. Their very tight orbits around the black hole pose a mystery: did these intrepid stars somehow manage to form in situ, or did they instead migrate to their current locations from further out?For a star to be born out of a molecular cloud, the self-gravity of the cloud clump must be stronger than the other forces its subject to. Close to a supermassive black hole, the brutal tidal forces of the black hole dominate over all else. For this reason, it was thought that stars couldnt form in the hostile environment near a supermassive black hole until clues came along suggesting otherwise.Science as an Iterative ProcessVery Large Array observations of candidate photoevaporative protoplanetary disks discovered in 2015. [Yusef-Zadeh et al. 2015]Longtime AAS Nova readers might recall that one of our very first highlights on the site, back in August of 2015, was of a study led by Farhad Yusef-Zadeh of Northwestern University. In this study, the authors presented observations of candidate proplyds photoevaporative protoplanetary disks suggestive of star formation within a few light-years of the galactic center.While these observations seemed to indicate that stars might, even now, be actively forming near Sgr A*, they werent conclusive evidence. Follow-up observations of these and other signs of possible star formation were hindered by the challenges of observing the distant and crowded galactic center.Two and a half years later, Yusef-Zadeh and collaborators are back now aided by high-resolution and high-sensitivity observations

  12. Lectures on Quantum Black Holes

    CERN Document Server

    Dabholkar, Atish

    2012-01-01

    In these notes we describe recent progress in understanding finite size corrections to the black hole entropy. Much of the earlier work concerning quantum black holes has been in the limit of large charges when the area of the even horizon is also large. In recent years there has been substantial progress in understanding the entropy of supersymmetric black holes within string theory going well beyond the large charge limit. It has now become possible to begin exploring finite size effects in perturbation theory in inverse size and even nonperturbatively, with highly nontrivial agreements between thermodynamics and statistical mechanics. Unlike the leading Bekenstein-Hawking entropy which follows from the two-derivative Einstein-Hilbert action, these finite size corrections depend sensitively on the phase under consideration and contain a wealth of information about the details of compactification as well as the spectrum of nonperturbative states in the theory. Finite-size corrections are therefore very inter...

  13. Massive Black Holes and Galaxies

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discuss measurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.

  14. The black hole quantum atmosphere

    Science.gov (United States)

    Dey, Ramit; Liberati, Stefano; Pranzetti, Daniele

    2017-11-01

    Ever since the discovery of black hole evaporation, the region of origin of the radiated quanta has been a topic of debate. Recently it was argued by Giddings that the Hawking quanta originate from a region well outside the black hole horizon by calculating the effective radius of a radiating body via the Stefan-Boltzmann law. In this paper we try to further explore this issue and end up corroborating this claim, using both a heuristic argument and a detailed study of the stress energy tensor. We show that the Hawking quanta originate from what might be called a quantum atmosphere around the black hole with energy density and fluxes of particles peaked at about 4 MG, running contrary to the popular belief that these originate from the ultra high energy excitations very close to the horizon. This long distance origin of Hawking radiation could have a profound impact on our understanding of the information and transplanckian problems.

  15. Black holes and galaxy formation

    CERN Document Server

    Propst, Raphael J

    2010-01-01

    Galaxies are the basic unit of cosmology. The study of galaxy formation is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning. The physics of galaxy formation is complicated because it deals with the dynamics of stars, thermodynamics of gas and energy production of stars. A black hole is a massive object whose gravitational field is so intense that it prevents any form of matter or radiation to escape. It is hypothesized that the most massive galaxies in the universe- "elliptical galaxies"- grow simultaneously with the supermassive black holes at their centers, giving us much stronger evidence that black holes control galaxy formation. This book reviews new evidence in the field.

  16. Black holes and random matrices

    Science.gov (United States)

    Cotler, Jordan S.; Gur-Ari, Guy; Hanada, Masanori; Polchinski, Joseph; Saad, Phil; Shenker, Stephen H.; Stanford, Douglas; Streicher, Alexandre; Tezuka, Masaki

    2017-05-01

    We argue that the late time behavior of horizon fluctuations in large anti-de Sitter (AdS) black holes is governed by the random matrix dynamics characteristic of quantum chaotic systems. Our main tool is the Sachdev-Ye-Kitaev (SYK) model, which we use as a simple model of a black hole. We use an analytically continued partition function | Z( β + it)|2 as well as correlation functions as diagnostics. Using numerical techniques we establish random matrix behavior at late times. We determine the early time behavior exactly in a double scaling limit, giving us a plausible estimate for the crossover time to random matrix behavior. We use these ideas to formulate a conjecture about general large AdS black holes, like those dual to 4D super-Yang-Mills theory, giving a provisional estimate of the crossover time. We make some preliminary comments about challenges to understanding the late time dynamics from a bulk point of view.

  17. Lee–Wick black holes

    Directory of Open Access Journals (Sweden)

    Cosimo Bambi

    2017-01-01

    Full Text Available We derive and study an approximate static vacuum solution generated by a point-like source in a higher derivative gravitational theory with a pair of complex conjugate ghosts. The gravitational theory is local and characterized by a high derivative operator compatible with Lee–Wick unitarity. In particular, the tree-level two-point function only shows a pair of complex conjugate poles besides the massless spin two graviton. We show that singularity-free black holes exist when the mass of the source M exceeds a critical value Mcrit. For M>Mcrit the spacetime structure is characterized by an outer event horizon and an inner Cauchy horizon, while for M=Mcrit we have an extremal black hole with vanishing Hawking temperature. The evaporation process leads to a remnant that approaches the zero-temperature extremal black hole state in an infinite amount of time.

  18. The black hole quantum atmosphere

    Directory of Open Access Journals (Sweden)

    Ramit Dey

    2017-11-01

    Full Text Available Ever since the discovery of black hole evaporation, the region of origin of the radiated quanta has been a topic of debate. Recently it was argued by Giddings that the Hawking quanta originate from a region well outside the black hole horizon by calculating the effective radius of a radiating body via the Stefan–Boltzmann law. In this paper we try to further explore this issue and end up corroborating this claim, using both a heuristic argument and a detailed study of the stress energy tensor. We show that the Hawking quanta originate from what might be called a quantum atmosphere around the black hole with energy density and fluxes of particles peaked at about 4MG, running contrary to the popular belief that these originate from the ultra high energy excitations very close to the horizon. This long distance origin of Hawking radiation could have a profound impact on our understanding of the information and transplanckian problems.

  19. Holes at High Blowing Ratios

    Directory of Open Access Journals (Sweden)

    Phillip M. Ligrani

    1996-01-01

    Full Text Available Experimental results are presented which describe the development and structure of flow downstream of a single row of holes with compound angle orientations producing film cooling at high blowing ratios. This film cooling configuration is important because similar arrangements are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 6d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 1.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes.

  20. Tuning the conductivity of vanadium dioxide films on silicon by swift heavy ion irradiation

    Directory of Open Access Journals (Sweden)

    H. Hofsäss

    2011-09-01

    Full Text Available We demonstrate the generation of a persistent conductivity increase in vanadium dioxide thin films grown on single crystal silicon by irradiation with 1 GeV 238U swift heavy ions at room temperature. VO2 undergoes a temperature driven metal-insulator-transition (MIT at 67 °C. After room temperature ion irradiation with high electronic energy loss of 50 keV/nm the conductivity of the films below the transition temperature is strongly increased proportional to the ion fluence of 5·109 U/cm2 and 1·1010 U/cm2. At high temperatures the conductivity decreases slightly. The ion irradiation slightly reduces the MIT temperature. This observed conductivity change is persistent and remains after heating the samples above the transition temperature and subsequent cooling. Low temperature measurements down to 15 K show no further MIT below room temperature. Although the conductivity increase after irradiation at such low fluences is due to single ion track effects, atomic force microscopy (AFM measurements do not show surface hillocks, which are characteristic for ion tracks in other materials. Conductive AFM gives no evidence for conducting ion tracks but rather suggests the existence of conducting regions around poorly conducting ion tracks, possible due to stress generation. Another explanation of the persistent conductivity change could be the ion-induced modification of a high resistivity interface layer formed during film growth between the vanadium dioxide film and the n-Silicon substrate. The swift heavy ions may generate conducting filaments through this layer, thus increasing the effective contact area. Swift heavy ion irradiation can thus be used to tune the conductivity of VO2 films on silicon substrates.

  1. Results from the NuSTAR Survey of Swift/BAT AGN

    Science.gov (United States)

    Balokovic, Mislav; Harrison, Fiona

    2015-08-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the spectral window above 10 keV with unprecedented spatial resolution and two orders of magnitude better sensitivity than any other instrument operating in that energy range. As a part of its long-term extragalactic program NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT). We present results based on 15-25 ks observations of ~150 Swift/BAT AGN surveyed in the first 2.5 years of NuSTAR operation. This sample forms an atlas of the highest quality hard X-ray spectra available to date for a large number of AGN. Assuming a range of hard X-ray spectral models, phenomenological as well as physically motivated, we constrain the main spectral parameters for each source individually and test the applicability of the models on a large sample for the first time. This analysis allows us to determine distributions of the main spectral parameters (spectral index, high-energy cut-off, absorption column, reflection strength, iron line equivalent width) in a well-defined population of nearby AGN. We find that approximately 70% of obscured AGN spectra can be well modeled in terms of simple models used in the literature, while the rest requires careful consideration of more advanced models. We will discuss the implications for the local AGN population, the effects on interpretation of high-redshift AGN observations, and the limitations of the current results.

  2. Unveiling Gargantua: A new search strategy for the most massive central cluster black holes

    Science.gov (United States)

    Brockamp, M.; Baumgardt, H.; Britzen, S.; Zensus, A.

    2016-01-01

    Aims: We aim to unveil the most massive central cluster black holes in the Universe. Methods: We present a new search strategy, which is based on a black hole mass gain sensitive calorimeter and which links the innermost stellar density profile of a galaxy to the adiabatic growth of its central supermassive black hole (SMBH). As a first step we convert observationally inferred feedback powers into SMBH growth rates using reasonable energy conversion efficiency parameters, ɛ. In the main part of this paper we use these black hole growth rates, sorted in logarithmically increasing steps encompassing our whole parameter space, to conduct N-body computations of brightest cluster galaxies (BCGs) with the newly developed Muesli software. For the initial setup of galaxies, we use core-Sérsic models to account for SMBH scouring. Results: We find that adiabatically driven core regrowth is significant at the highest accretion rates. As a result, the most massive black holes should be located in BCGs with less pronounced cores when compared to the predictions of empirical scaling relations, which are usually calibrated in less extreme environments. For efficiency parameters ɛ< 0.1, BCGs in the most massive, relaxed, and X-ray luminous galaxy clusters might even develop steeply rising density cusps. Finally, we discuss several promising candidates for follow-up investigations, among them the nuclear black hole in the Phoenix cluster. Based on our results, its central black hole might have a mass of the order of 1011 M⊙.

  3. Macular Hole in Behcet's Disease

    Directory of Open Access Journals (Sweden)

    Shwu-Jiuan Sheu

    2004-11-01

    Full Text Available Behcet's disease is an inflammatory disorder of unknown cause, characterized by recurrent oral aphthous ulcers, genital ulcers, uveitis, and skin lesions. Ocular involvement occurs in 60-80% of patients with Behcet's disease and presents as panuveitis in most cases. Posterior segment involvement may lead to irreversible alterations and significant vision loss. The development of a partial or full-thickness macular hole, though rarely reported, may cause serious vision loss. In this report, we present two cases of macular hole in the worse eye of bilateral cases of Behcet's disease, and discuss the possible mechanisms and management in such cases.

  4. Fronts between hexagons and squares in a generalized Swift-Hohenberg equation

    DEFF Research Database (Denmark)

    Kubstrup, Christian; Herrero, H.; Pérez-García, C.

    1996-01-01

    Pinning effects in domain walls separating different orientations in patterns in nonequilibrium systems, are studied. Usually; theoretical studies consider perfect structures, but in experiments, point defects, grain boundaries, etc., always appear. The aim of this paper is to perform an analysis...... of the stability of fronts between hexagons and squares in a generalized Swift-Hohenberg model equation. We focus the analysis on pinned fronts between domains with different symmetries by using amplitude equations and by considering the small-scale structure in the pattern. The conditions for pinning effects...

  5. Swift/BAT spectral analysis of the Crab after September 2010 gamma-ray flare

    Science.gov (United States)

    Sakamoto, T.; Barthelmy, S. D.; Baumgartner, W. H.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Stamatikos, M.; Tueller, J.; Ukwatta, T. N.

    2010-09-01

    We report the Swift/BAT detailed analysis of the Crab data from September 2010 when a gamma-ray flare has been observed by AGILE (Atel#2855) and Fermi/LAT (Atel#2861). We found no significant variation in either the 15-150 keV flux and the photon index during this period. We collected the BAT survey data (Detector Plane Histograms) when the Crab was in the BAT field of view. We used the mask weighting technique to construct a spectrum of the Crab for each pointing.

  6. Swift follow-up of 1RXS J194211.9+255552

    DEFF Research Database (Denmark)

    Sidoli, L.; Fiocchi, M.; Bird, A. J.

    2011-01-01

    resulted in a much worse fit (reduced chi_sq = 1.367 for 36 dof). The source is a factor of 2.5 fainter than during the Jem-X detection (ATel #3816), two days before. This is the first characterization of the source X-ray spectrum. A search at other wavelengths resulted in a possible counterpart in the 2...... would like to thank the Swift Team for making these observations possible, in particular Neil Gehrels, the duty scientists and the science planners....

  7. Charge-state related effects in sputtering of LiF by swift heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Assmann, W. [Ludwig-Maximilians-Universität München, 85748 Garching (Germany); Ban-d' Etat, B. [Centre de Recherche sur les Ions, les Matériaux et la photonique, CIMAP-GANIL, CEA–CNRS–ENSICAEN–Univ. Caen, 14070 Caen (France); Bender, M. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany); Boduch, P. [Centre de Recherche sur les Ions, les Matériaux et la photonique, CIMAP-GANIL, CEA–CNRS–ENSICAEN–Univ. Caen, 14070 Caen (France); Grande, P.L. [Univ. Fed. Rio Grande do Sul, BR-91501970 Porto Alegre, RS (Brazil); Lebius, H.; Lelièvre, D. [Centre de Recherche sur les Ions, les Matériaux et la photonique, CIMAP-GANIL, CEA–CNRS–ENSICAEN–Univ. Caen, 14070 Caen (France); Marmitt, G.G. [Univ. Fed. Rio Grande do Sul, BR-91501970 Porto Alegre, RS (Brazil); Rothard, H. [Centre de Recherche sur les Ions, les Matériaux et la photonique, CIMAP-GANIL, CEA–CNRS–ENSICAEN–Univ. Caen, 14070 Caen (France); Seidl, T.; Severin, D.; Voss, K.-O. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany); Toulemonde, M., E-mail: toulemonde@ganil.fr [Centre de Recherche sur les Ions, les Matériaux et la photonique, CIMAP-GANIL, CEA–CNRS–ENSICAEN–Univ. Caen, 14070 Caen (France); Trautmann, C. [GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt (Germany); Technische Universität Darmstadt, 64289 Darmstadt (Germany)

    2017-02-01

    Sputtering experiments with swift heavy ions in the electronic energy loss regime were performed by using the catcher technique in combination with elastic recoil detection analysis. The angular distribution of particles sputtered from the surface of LiF single crystals is composed of a jet-like peak superimposed on a broad isotropic distribution. By using incident ions of fixed energy but different charges states, the influence of the electronic energy loss on both components is probed. We find indications that isotropic sputtering originates from near-surface layers, whereas the jet component may be affected by contributions from depth up to about 150 nm.

  8. Swift heavy ion induced nano-dimensional phase separation in liquid immiscible binary Mn-Bi

    Science.gov (United States)

    Srivastava, S. K.; Khan, S. A.; Sudheer Babu, P.; Avasthi, D. K.

    2014-08-01

    Pulsed laser deposited 60 nm thin film of homogeneous Mn0.82Bi0.18 composite has been irradiated by 100 MeV Au ions at fluence 1 × 1013 ions/cm2, and investigated by field emission scanning electron microscopy, X-ray diffraction, magnetic hysteresis, X-ray photoelectron spectroscopy, and nanoindentation measurements. Dispersed nanostructures of soft Bi-rich phase of about 20 nm diameter emerged in a hard Mn-rich matrix on irradiation. Such structures, as synthesized by the present novel swift heavy ion irradiation approach, are usable as self-lubricating thin films.

  9. Swift heavy ion induced nano-dimensional phase separation in liquid immiscible binary Mn–Bi

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, S.K., E-mail: sanjeev@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India); Khan, S.A. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India); Sudheer Babu, P. [Department of Physics, RGUKT, Nuzvid 521201 (India); Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India)

    2014-08-01

    Pulsed laser deposited 60 nm thin film of homogeneous Mn{sub 0.82}Bi{sub 0.18} composite has been irradiated by 100 MeV Au ions at fluence 1 × 10{sup 13} ions/cm{sup 2}, and investigated by field emission scanning electron microscopy, X-ray diffraction, magnetic hysteresis, X-ray photoelectron spectroscopy, and nanoindentation measurements. Dispersed nanostructures of soft Bi-rich phase of about 20 nm diameter emerged in a hard Mn-rich matrix on irradiation. Such structures, as synthesized by the present novel swift heavy ion irradiation approach, are usable as self-lubricating thin films.

  10. iOS Game Development using SpriteKit Framework with Swift Programming Language

    OpenAIRE

    Gurung, Lal

    2016-01-01

    iOS is a mobile operating system for Apple manufactured phones and tablets. Mobile Gaming Industries are growing very fast, and compatibility with iOS is becoming very popular among game developers. The aim of this Bachelor’s thesis was to find the best available game development tools for iOS platform. The 2D game named Lapland was developed using Apple’s own native framework, SpriteKit. The game was written with the SpriteKit programming language. The combination of SpriteKit and Swift...

  11. Exploring the Pulse Structure of the Gamma-Ray Bursts from the Swift Burst Alert Telescop

    Science.gov (United States)

    Martinez, Juan-Carlos; Team 1: Jon Hakkila, Amy Lien, Judith, Racusin, Team 2: Antonino Cucchiara, David Morris

    2018-01-01

    Gamma-ray bursts (GRBs) are one of the brightest and most intense explosions in our universe. For this project, we studied the shape of 400 single pulse GRBs using data gathered from Swift's Burst Alert Telescope (BAT). Hakkila et al. (2015) have discovered a mathematical Model that describes the GRB’s pulse shapes. Following the method in Hakkila et al. (2015), we fit GRB pulses with the Norris function and examined the residual in the fitting, to see whether the results are consistent with the one reported in Hakkila et al. (2015).

  12. The seven year Swift-XRT point source catalog (1SWXRT)

    Science.gov (United States)

    D'Elia, Valerio

    2015-08-01

    The Swift satellite is a multi-wavelength observatory specifically designed for gamma-ray burst (GRB) astronomy that is operational since 2004. Swift is also a very flexible multi-purpose facility that supports a wide range of scientific fields such as active galactic nuclei, supernovae, cataclysmic variables, Galactic transients, active stars and comets. The Swift X-ray Telescope (XRT) has collected more than 150 Ms of observations in its first seven years of operations.The purpose of this work is to present to the scientific community the list of all the X-ray point sources detected in XRT imaging data taken in photon counting mode during the first seven years of Swift operations. All these point-like sources, excluding the Gamma-Ray Bursts (GRB), are stored in a catalog publicly available (1SWXRT).We consider all the XRT observations with exposure time longer than 500 s taken in the period 2005-2011. Data were reduced and analyzed with standard techniques and a list of detected sources for each observation was produced. A careful visual inspection was performed to remove extended, spurious and piled-up sources. Finally, positions, count rates, fluxes and the corresponding uncertainties were computed.We have analyzed more than 35,000 XRT fields, with exposures ranging between 500 s and 100 ks, for a total exposure time of almost 140 Ms. The catalog includes approximately 89,400 entries, of which more than 85,000 are not affected by pile-up and are not GRBs. Considering that many XRT fields were observed several times, we have a total of ~ 36,000 distinct celestial sources. We computed count rates in three energy bands: 0.3-10 keV (Full, or F), 0.3-3 keV (Soft, or S) and 2-10 keV (Hard, or H). Each entry has a detection in at least one of these bands. In particular, we detect ~ 80,000, ~ 70,000 and ~ 25,500 in the F, S and H band, respectively. Count rates were converted into fluxes in the 0.5-10, 0.5-2 and 2-10 keV bands. The flux interval sampled by the detected

  13. Swift heavy ion irradiation induced electrical degradation in deca-nanometer MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yao; Yang, Zhimei; Gong, Min [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Gao, Bo; Li, Yun; Lin, Wei; Li, Jinbo; Xia, Zhuohui [Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China)

    2016-09-15

    In this work, degradation of the electrical characteristics of 65 nm nMOSFETs under swift heavy ion irradiation is investigated. It was found that a heavy ion can generate a localized region of physical damage (ion latent track) in the gate oxide. This is the likely cause for the increased gate leakage current and soft breakdown (SBD) then hard breakdown (HBD) of the gate oxide. Except in the case of HBD, the devices retain their functionality but with degraded transconductance. The degraded gate oxide exhibits early breakdown behavior compatible with the model of defect generation and percolation path formation in the percolation model.

  14. Pentalum SpiDAR Deployment at SWiFT FY17.

    Energy Technology Data Exchange (ETDEWEB)

    Westergaard, Carsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pol, Suhas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pereira, Tassia [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Castillo, Ricardo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-12-01

    The Texas Tech University ( TTU ) research group is actively studying the wake development of wind turbines, as part of developing innovative wake control strategies to improve the performance of wind farms. Recently, the team received a set of five new gro und lidars to perform field measurements at the Sandia National Laboratories SWiFT site. This document describes tests details including configurations, timeframe, hardware, and the required collaboration from the Sandia team. This test plan will facili tate the coordination between both TTU and the Sandia team in terms of site accessibility, staff training, and data sharing to meet the specific objectives of the tests.

  15. Jet Power and Black Hole Assortment Revealed in New Chandra Image

    Science.gov (United States)

    2008-01-01

    A dramatic new Chandra image of the nearby galaxy Centaurus A provides one of the best views to date of the effects of an active supermassive black hole. Opposing jets of high-energy particles can be seen extending to the outer reaches of the galaxy, and numerous smaller black holes in binary star systems are also visible. The image was made from an ultra-deep look at the galaxy Centaurus A, equivalent to more than seven days of continuous observations. Centaurus A is the nearest galaxy to Earth that contains a supermassive black hole actively powering a jet. X-ray Image of Centaurus A, Labeled X-ray Image of Centaurus A, Labeled A prominent X-ray jet extending for 13,000 light years points to the upper left in the image, with a shorter "counterjet" aimed in the opposite direction. Astronomers think that such jets are important vehicles for transporting energy from the black hole to the much larger dimensions of a galaxy, and affecting the rate at which stars form there. High-energy electrons spiraling around magnetic field lines produce the X-ray emission from the jet and counterjet. This emission quickly saps the energy from the electrons, so they must be continually reaccelerated or the X-rays will fade out. Knot-like features in the jets detected in the Chandra image show where the acceleration of particles to high energies is currently occurring, and provides important clues to understanding the process that accelerates the electrons to near-light speeds. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Chandra Data Reveal Rapidly Whirling Black Holes Erratic Black Hole Regulates Itself The inner part of the X-ray jet close to the black hole is dominated by these knots of X-ray emission, which probably come from shock waves -- akin to sonic booms -- caused by the jet. Farther from the black hole there is more diffuse X-ray emission in the jet. The cause of particle

  16. Building a Parallel Cloud Storage System using OpenStack’s Swift Object Store and Transformative Parallel I/O

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Andrew J. [Los Alamos National Laboratory; Lora, Kaleb D. [Los Alamos National Laboratory; Martinez, Esteban [Los Alamos National Laboratory; Shorter, Martel L. [Los Alamos National Laboratory

    2012-07-30

    Our project consists of bleeding-edge research into replacing the traditional storage archives with a parallel, cloud-based storage solution. It used OpenStack's Swift Object Store cloud software. It's Benchmarked Swift for write speed and scalability. Our project is unique because Swift is typically used for reads and we are mostly concerned with write speeds. Cloud Storage is a viable archive solution because: (1) Container management for larger parallel archives might ease the migration workload; (2) Many tools that are written for cloud storage could be utilized for local archive; and (3) Current large cloud storage practices in industry could be utilized to manage a scalable archive solution.

  17. Improved Black Hole Fireworks: Asymmetric Black-Hole-to-White-Hole Tunneling Scenario

    CERN Document Server

    De Lorenzo, Tommaso

    2015-01-01

    A new scenario for gravitational collapse has been recently proposed by Haggard and Rovelli. Presenting the model under the name of black hole fireworks, they claimed that the accumulation of quantum gravitational effects outside the horizon can cause the tunneling of geometry from a black hole to a white hole, allowing a bounce of the collapsing star which can eventually go back to infinity. In this paper we discuss the instabilities of this model and propose a simple minimal modification which eliminates them, as well as other related instabilities discussed in the literature. The new scenario is a time-asymmetric version of the original model with a time-scale for the final explosion that is shorter than m log m in Planck units. Our analysis highlights the importance of irreversibility in gravitational collapse which, in turn, uncovers important issues that cannot be addressed in detail without a full quantum gravity treatment.

  18. Probing the Cosmic Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope

    Science.gov (United States)

    Lien, Amy; Sakamoto, Takanori; Gehrels, Neil; Palmer, David M.; Barthelmy, Scott D.; Graziani, Carlo; Cannizzo, John K.

    2013-01-01

    The gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early universe. While hundreds of GRBs are observed by Swift, it remains difficult to determine the intrinsic GRB rate due to the complex trigger algorithm of Swift. Current studies of the GRB rate usually approximate the Swift trigger algorithm by a single detection threshold. However, unlike the previously own GRB instruments, Swift has over 500 trigger criteria based on photon count rate and additional image threshold for localization. To investigate possible systematic biases and explore the intrinsic GRB properties, we develop a program that is capable of simulating all the rate trigger criteria and mimicking the image threshold. Our simulations show that adopting the complex trigger algorithm of Swift increases the detection rate of dim bursts. As a result, our simulations suggest bursts need to be dimmer than previously expected to avoid over-producing the number of detections and to match with Swift observations. Moreover, our results indicate that these dim bursts are more likely to be high redshift events than low-luminosity GRBs. This would imply an even higher cosmic GRB rate at large redshifts than previous expectations based on star-formation rate measurements, unless other factors, such as the luminosity evolution, are taken into account. The GRB rate from our best result gives a total number of 4568 +825 -1429 GRBs per year that are beamed toward us in the whole universe.

  19. Swift heavy ion irradiation damage in Ti-6Al-4V and Ti-6Al-4V-1B: Study of the microstructure and mechanical properties

    Science.gov (United States)

    Amroussia, Aida; Avilov, Mikhail; Boehlert, Carl J.; Durantel, Florent; Grygiel, Clara; Mittig, Wolfgang; Monnet, Isabelle; Pellemoine, Frederique

    2015-12-01

    The α + β alloy Ti-6Al-4V (wt.%) and the boron-modified Ti-6Al-4V-1B (wt.%), due to their low activation, corrosion resistance, good mechanical properties, and their commercial availability, were chosen as candidate materials for the beam dump for the Facility for Rare Isotope Beams (FRIBs) at Michigan State University: a new generation accelerator with high power heavy ion beams. Through this study our goal is to establish the first irradiation data of the recently developed Ti-6Al-4V-1B (wt.%) alloy and investigate the changes in microstructure and mechanical properties of Ti-6Al-4V due to swift heavy ion (SHI) irradiation damage. The results of hardness measurements showed that the studied Ti-6Al-4V (wt.%) and Ti-6Al-4V-1B (wt.%) alloy, under the specified irradiation conditions, exhibited a high irradiation resistance. In fact, only a slight hardening was observed (∼13%) in the tested samples and no changes in the microstructure were observed. Temperature, dose and electronic excitation effects were also discussed.

  20. Black Holes and Exotic Spinors

    Directory of Open Access Journals (Sweden)

    J. M. Hoff da Silva

    2016-05-01

    Full Text Available Exotic spin structures are non-trivial liftings, of the orthogonal bundle to the spin bundle, on orientable manifolds that admit spin structures according to the celebrated Geroch theorem. Exotic spin structures play a role of paramount importance in different areas of physics, from quantum field theory, in particular at Planck length scales, to gravity, and in cosmological scales. Here, we introduce an in-depth panorama in this field, providing black hole physics as the fount of spacetime exoticness. Black holes are then studied as the generators of a non-trivial topology that also can correspond to some inequivalent spin structure. Moreover, we investigate exotic spinor fields in this context and the way exotic spinor fields branch new physics. We also calculate the tunneling probability of exotic fermions across a Kerr-Sen black hole, showing that the exotic term does affect the tunneling probability, altering the black hole evaporation rate. Finally we show that it complies with the Hawking temperature universal law.

  1. Black Holes in Our Universe

    Indian Academy of Sciences (India)

    Abstract. Current technologies have enabled glimpses at the many facetsof black holes, which we know to be plentiful in our cosmos.A panoramic view of the evidence for them is presented hereacross the large range of masses that they span.

  2. Extremal Higher Spin Black Holes

    NARCIS (Netherlands)

    Bañados, M.; Castro, A.; Faraggi, A.; Jottar, J.I.

    The gauge sector of three-dimensional higher spin gravities can be formulated as a Chern-Simons theory. In this context, a higher spin black hole corresponds to a flat connection with suitable holonomy (smoothness) conditions which are consistent with the properties of a generalized thermal

  3. From Pinholes to Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-10-06

    Pinhole photography has made major contributions to astrophysics through the use of “coded apertures”. Coded apertures were instrumental in locating gamma-ray bursts and proving that they originate in faraway galaxies, some from the birth of black holes from the first stars that formed just after the big bang.

  4. Rotating black hole and quintessence

    CERN Document Server

    Ghosh, Sushant G

    2015-01-01

    We discuss spherically symmetric exact solutions of the Einstein equations for quintessential matter surrounding a black hole (BH), which has additional parameters ($\\alpha$ and $\\omega$) due to the quintessential matter, apart from the mass ($M$). In turn, we employ the Newman\\(-\\)Janis complex transformation to this spherical quintessence BH solution and present a rotating counterpart that is identified, for $\\alpha=-e^2 \

  5. 'Black holes': escaping the void.

    Science.gov (United States)

    Waldron, Sharn

    2013-02-01

    The 'black hole' is a metaphor for a reality in the psyche of many individuals who have experienced complex trauma in infancy and early childhood. The 'black hole' has been created by an absence of the object, the (m)other, so there is no internalized object, no (m)other in the psyche. Rather, there is a 'black hole' where the object should be, but the infant is drawn to it, trapped by it because of an intrinsic, instinctive need for a 'real object', an internalized (m)other. Without this, the infant cannot develop. It is only the presence of a real object that can generate the essential gravity necessary to draw the core of the self that is still in an undeveloped state from deep within the abyss. It is the moving towards a real object, a (m)other, that relativizes the absolute power of the black hole and begins a reformation of its essence within the psyche. © 2013, The Society of Analytical Psychology.

  6. Black Hole Macro-Quantumness

    CERN Document Server

    Dvali, Gia

    2014-01-01

    It is a common wisdom that properties of macroscopic bodies are well described by (semi)classical physics. As we have suggested this wisdom is not applicable to black holes. Despite being macroscopic, black holes are quantum objects. They represent Bose-Einstein condensates of N-soft gravitons at the quantum critical point, where N Bogoliubov modes become gapless. As a result, physics governing arbitrarily-large black holes (e.g., of galactic size) is a quantum physics of the collective Bogoiliubov modes. This fact introduces a new intrinsically-quantum corrections in form of 1/N, as opposed to exp(-N). These corrections are unaccounted by the usual semiclassical expansion in h and cannot be recast in form of a quantum back-reaction to classical metric. Instead the metric itself becomes an approximate entity. These 1/N corrections abolish the presumed properties of black holes, such as non existence of hair, and are the key to nullifying the so-called information paradox.

  7. Swift follow-up observations of the blazar PKS 1510-089 after a high optical flare

    Science.gov (United States)

    D'Ammando, F.; Krimm, H.; Romano, P.; Vercellone, S.

    2009-05-01

    Following the extraordinary optical brightness level of the blazar PKS 1510-089 on May 08.9 (Larionov et al., ATel #2045), we report on the analysis of Swift data obtained immediately after the optical flare. The Swift/BAT hard X-ray transient monitor detected an outburst in PKS 1510-089 in the 15-50 keV energy band. On 2009 May 10 (MJD 54961) the count rate was 0.009 +/- 0.005 cts/s/cm^2 (40 mCrab).

  8. SWIFT2: Software for continuous ensemble short-term streamflow forecasting for use in research and operations

    Science.gov (United States)

    Perraud, Jean-Michel; Bennett, James C.; Bridgart, Robert; Robertson, David E.

    2016-04-01

    Research undertaken through the Water Information Research and Development Alliance (WIRADA) has laid the foundations for continuous deterministic and ensemble short-term forecasting services. One output of this research is the software Short-term Water Information Forecasting Tools version 2 (SWIFT2). SWIFT2 is developed for use in research on short term streamflow forecasting techniques as well as operational forecasting services at the Australian Bureau of Meteorology. The variety of uses in research and operations requires a modular software system whose components can be arranged in applications that are fit for each particular purpose, without unnecessary software duplication. SWIFT2 modelling structures consist of sub-areas of hydrologic models, nodes and links with in-stream routing and reservoirs. While this modelling structure is customary, SWIFT2 is built from the ground up for computational and data intensive applications such as ensemble forecasts necessary for the estimation of the uncertainty in forecasts. Support for parallel computation on multiple processors or on a compute cluster is a primary use case. A convention is defined to store large multi-dimensional forecasting data and its metadata using the netCDF library. SWIFT2 is written in modern C++ with state of the art software engineering techniques and practices. A salient technical feature is a well-defined application programming interface (API) to facilitate access from different applications and technologies. SWIFT2 is already seamlessly accessible on Windows and Linux via packages in R, Python, Matlab and .NET languages such as C# and F#. Command line or graphical front-end applications are also feasible. This poster gives an overview of the technology stack, and illustrates the resulting features of SWIFT2 for users. Research and operational uses share the same common core C++ modelling shell for consistency, but augmented by different software modules suitable for each context. The

  9. Inflation and dark matter primordial black holes

    Energy Technology Data Exchange (ETDEWEB)

    Erfani, Encieh

    2012-09-15

    In this thesis a broad range of single field models of inflation are analyzed in light of all relevant recent cosmological data, checking whether they can lead to the formation of long-lived Primordial Black Holes (PBHs) to serve as candidates for Dark Matter. To that end we calculate the spectral index of the power spectrum of primordial perturbations as well as its first and second derivatives. PBH formation is possible only if the spectral index increases significantly at small scales, i.e. large wave number k. Since current data indicate that the first derivative {alpha}{sub S} of the spectral index n{sub S}(k{sub pivot}) is negative at the pivot scale k{sub pivot}, PBH formation is only possible in the presence of a sizable and positive second derivative (''running of the running'') {beta}{sub S}. Among the three small-field and five large-field inflation models we analyze, only one small-field model, the ''running-mass'' model, allows PBH formation, for a narrow range of parameters. We also note that none of the models we analyze can accord for a large and negative value of {alpha}{sub S}, which is weakly preferred by current data. Similarly, proving conclusively that the second derivative of the spectral index is positive would exclude all the large-field models we investigated.

  10. Supersymmetric black holes and Freudenthal duality

    Science.gov (United States)

    Marrani, Alessio; Mandal, Taniya; Tripathy, Prasanta K.

    2017-07-01

    We study the effect of Freudenthal duality on supersymmetric extremal black hole attractors in 𝒩 = 2, D = 4 ungauged supergravity. Freudenthal duality acts on the dyonic black hole charges as an anti-involution which keeps the black hole entropy and the critical points of the effective black hole potential invariant. We analyze its effect on the recently discovered distinct, mutually exclusive phases of axionic supersymmetric black holes, related to the existence of nontrivial involutory constant matrices. In particular, we consider a supersymmetric D0 - D4 - D6 black hole and we explicitly Freudenthal-map it to a supersymmetric D0 - D2 - D4 - D6 black hole. We thus show that the charge representation space of a supersymmetric D0 - D2 - D4 - D6 black hole also contains mutually exclusive domains.

  11. Spin distribution of primordial black holes

    Science.gov (United States)

    Chiba, Takeshi; Yokoyama, Shuichiro

    2017-08-01

    We estimate the spin distribution of primordial black holes based on the recent study of the critical phenomena in the gravitational collapse of a rotating radiation fluid. We find that primordial black holes are mostly slowly rotating.

  12. Implementing black hole as efficient power plant

    CERN Document Server

    Wei, Shao-Wen

    2016-01-01

    Treating the black hole molecules as working substance and considering its phase structure, we study the black hole heat engine by a charged anti-de Sitter black hole. In the reduced temperature-entropy chart, it is found that the work, heat, and efficiency of the engine are independent of the black hole charge. Applying the Rankine cycle with or without a back pressure mechanism to the black hole heat engine, the efficiency is numerically solved. The result shows that the black hole engine working along the Rankine cycle with a back pressure mechanism has a higher efficiency. This provides a novel and efficient mechanism to produce the useful mechanical work with black hole, and such heat engine may act as a possible energy source for the high energy astrophysical phenomena near the black hole.

  13. Mass Inflation in the Loop Black Hole

    CERN Document Server

    Brown, Eric G; Modesto, Leonardo

    2011-01-01

    In classical general relativity the Cauchy horizon within a two-horizon black hole is unstable via a phenomenon known as mass inflation, in which the mass parameter (and the spacetime curvature) of the black hole diverges at the Cauchy horizon. Here we study this effect for loop black holes -- quantum gravitationally corrected black holes from loop quantum gravity -- whose construction alleviates the $r=0$ singularity present in their classical counterparts. We use a simplified model of mass inflation, which makes use of the generalized DTR relation, to conclude that the Cauchy horizon of loop black holes indeed results in a curvature singularity similar to that found in classical black holes. The DTR relation is of particular utility in the loop black hole because it does not directly rely upon Einstein's field equations. We elucidate some of the interesting and counterintuitive properties of the loop black hole, and corroborate our results using an alternate model of mass inflation due to Ori.

  14. Foundations of Black Hole Accretion Disk Theory

    National Research Council Canada - National Science Library

    Abramowicz, Marek A; Fragile, P. Chris

    2013-01-01

    This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves...

  15. An application of Lorentz-invariance violation in black hole thermodynamics

    Science.gov (United States)

    Li, Guo-Ping; Pu, Jin; Jiang, Qing-Quan; Zu, Xiao-Tao

    2017-10-01

    In this paper, we have applied the Lorentz-invariance violation (LIV) class of dispersion relations (DRs) with the dimensionless parameter it{n}=2 and the "sign of LIV" η _+ = 1, to a phenomenological study of the effect of quantum gravity in a strong gravitational field. Specifically, we have studied the effect of the LIV-DR induced quantum gravity on the Schwarzschild black hole thermodynamics. The result shows that the effect of the LIV-DR induced quantum gravity speeds up the black hole evaporation, and its corresponding black hole entropy undergoes a leading logarithmic correction to the "reduced Bekenstein-Hawking entropy", and the ill-defined situations (i.e. the singularity problem and the critical problem) are naturally bypassed when the LIV-DR effect is present. Also, to put our results in a proper perspective, we have compared results with the earlier findings by another quantum-gravity candidate, i.e. the generalized uncertainty principle (GUP). Finally, we conclude from the inert remnants at the final stage of the black hole evaporation that, the GUP as a candidate for describing quantum gravity can always do as well as the LIV-DR by adjusting the model-dependent parameters, but in the same model-dependent parameters the LIV-DR acts as a more suitable candidate.

  16. Recent progress in the observations of compact objects and black holes

    CERN Document Server

    Stella, L

    1993-01-01

    Abstract. This paper reviews some of the recent observational results on compact objects and stellar mass black holes. Over the last decade, much of the progress in this field has been achieved through the study of transient X-ray binary sources, which shine only sporadically in the X—ray sky and undergo much larger luminosity variations than most persistent sources. The impact of the observations of the transient X—ray pulsar EXO 2030+375 on the study of accretion processes onto magnetic neutron stars is presented as one of the most significant examples. There are currently six stellar-mass black hole candidates for which the mass of the compact object is estimated to be well above the maximum neutron star mass. The three most recently identified black hole candidates of this kind belong to a class of transient X—ray sources with peculiar spectral properties. A number of transients of the same class which are currently being studied are likely to contain other black hole candidates. The increasing n...

  17. Time-resolved vortex wake of a common swift flying over a range of flight speeds

    Science.gov (United States)

    Henningsson, P.; Muijres, F. T.; Hedenström, A.

    2011-01-01

    The wake of a freely flying common swift (Apus apus L.) is examined in a wind tunnel at three different flight speeds, 5.7, 7.7 and 9.9 m s−1. The wake of the bird is visualized using high-speed stereo digital particle image velocimetry (DPIV). Wake images are recorded in the transverse plane, perpendicular to the airflow. The wake of a swift has been studied previously using DPIV and recording wake images in the longitudinal plane, parallel to the airflow. The high-speed DPIV system allows for time-resolved wake sampling and the result shows features that were not discovered in the previous study, but there was approximately a 40 per cent vertical force deficit. As the earlier study also revealed, a pair of wingtip vortices are trailing behind the wingtips, but in addition, a pair of tail vortices and a pair of ‘wing root vortices’ are found that appear to originate from the wing/body junction. The existence of wing root vortices suggests that the two wings are not acting as a single wing, but are to some extent aerodynamically detached from each other. It is proposed that this is due to the body disrupting the lift distribution over the wing by generating less lift than the wings. PMID:21131333

  18. SWIFT AND FERMI OBSERVATIONS OF X-RAY FLARES: THE CASE OF LATE INTERNAL SHOCK

    Energy Technology Data Exchange (ETDEWEB)

    Troja, E. [Center for Research and Exploration in Space Science and Technology, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Piro, L. [INAF-IAPS, Via Fosso del Cavaliere 100, I-00133 Rome (Italy); Vasileiou, V. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, and CNRS/IN2P3, Montpellier (France); Omodei, N. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Burgess, J. M.; Connaughton, V. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Cutini, S. [ASI Science Data Center, via Galileo Galilei, I-00044 Frascati (Italy); McEnery, J. E., E-mail: eleonora.troja@nasa.gov, E-mail: luigi.piro@iaps.inaf.it, E-mail: Vlasios.Vasileiou@lupm.in2p3.fr [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-04-10

    Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than 10 decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi during the first three years of Fermi operations. While bright in the X-ray band, X-ray flares are often undetected at lower (optical), and higher (MeV to GeV) energies. We show that this disfavors synchrotron self-Compton processes as the origin of the observed X-ray emission. We compare the broadband properties of X-ray flares with the standard late internal shock model, and find that in this scenario, X-ray flares can be produced by a late-time relativistic (Γ > 50) outflow at radii R ∼ 10{sup 13}-10{sup 14} cm. This conclusion holds only if the variability timescale is significantly shorter than the observed flare duration, and implies that X-ray flares can directly probe the activity of the GRB central engine.

  19. Swift and Fermi Observations of X-Ray Flares: The Case of Late Internal Shock

    Science.gov (United States)

    Troja, E.; Piro, L.; Vasileiou, V.; Omodei, N.; Burgess, J. M.; Cutini, S.; Connaughton, V.; McEnery, J. E.

    2015-01-01

    Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than 10 decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi during the first three years of Fermi operations. While bright in the X-ray band, X-ray flares are often undetected at lower (optical), and higher (MeV to GeV) energies. We show that this disfavors synchrotron self-Compton processes as the origin of the observed X-ray emission. We compare the broadband properties of X-ray flares with the standard late internal shock model, and find that in this scenario, X-ray flares can be produced by a late-time relativistic (gamma greater than 50) outflow at radii R approximately 10(exp 13) - 10(exp 14) cm. This conclusion holds only if the variability timescale is significantly shorter than the observed flare duration, and implies that X-ray flares can directly probe the activity of the GRB central engine.

  20. Mechanical response to swift ion irradiation-induced nano-tracks in silica

    Energy Technology Data Exchange (ETDEWEB)

    Páramo, Ángel R., E-mail: angel.rodriguez.paramo@upm.es [Instituto de Fusion Nuclear UPM, c/Jose Gutierrez Abascal, 2, E28006 Madrid (Spain); Sordo, F. [Instituto de Fusion Nuclear UPM, c/Jose Gutierrez Abascal, 2, E28006 Madrid (Spain); Consorcio ESS-Bilbao, Edificio Cosimet, Paseo Landabarri, 2 1" a planta, 48940 Leioa (Spain); Garoz, D.; Peña-Rodríguez, O.; Prada, A. [Instituto de Fusion Nuclear UPM, c/Jose Gutierrez Abascal, 2, E28006 Madrid (Spain); Olivares, J. [Centro de Micro-Análisis de Materiales UAM, 28049 Madrid (Spain); Instituto de Óptica, CSIC, c/Serrano 121, 28006 Madrid (Spain); Crespillo, M.L. [Centro de Micro-Análisis de Materiales UAM, 28049 Madrid (Spain); Perlado, J.M.; Rivera, A. [Instituto de Fusion Nuclear UPM, c/Jose Gutierrez Abascal, 2, E28006 Madrid (Spain)

    2015-06-01

    Ion irradiation on dielectric materials produces several processes, such ionization and defect formation followed by a decay governed by thermal processes such as heat diffusion and atomic rearrangement. Finally in the irradiated region the mechanical properties are altered, strain and stress fields appear, a densification takes places and other properties such as the refractive index are affected. In order to simulate the mechanical response of silica to swift ion irradiation we use a methodology based on molecular dynamics (MD) and finite element methods (FEM). We use information from MD to obtain the local densification generated by an incoming swift ion. Finally we calculate the densification in the ion track using FEM. This method provides information on the strain and stress field along the material as a function of ion irradiation fluence. For this work an experimental campaign using Br ions from 5 to 50 MeV has been done at CMAM accelerator (Madrid). We measured the refractive index and we observe that for high fluences the refractive index decreases. The effect of the strain field on the density could explain the decrease in the refractive index. We check this hypothesis using our methodology coupling MD and FEM.

  1. Swift and Strong NK Cell Responses Protect 129 Mice against High-Dose Influenza Virus Infection.

    Science.gov (United States)

    Zhou, Kai; Wang, Jing; Li, An; Zhao, Wenming; Wang, Dongfang; Zhang, Wei; Yan, Jinghua; Gao, George Fu; Liu, Wenjun; Fang, Min

    2016-02-15

    It is generally unclear what roles NK cells play during influenza virus infection with regard to different host genetic backgrounds. In this study, we show that in six inbred mouse strains, NK cells play an important protective role only in 129 mice during high-dose influenza A H1N1 virus infection. Swift and strong NK cell responses efficiently control early pulmonary viral replication in 129 mice, providing survival privilege. In addition, we identified that early activation of TLRs and RIG-I signaling in 129 mice resulted in quick production of type 1 IFNs and inflammatory cytokines, which are important reasons for the swift kinetics of NK cell responses post influenza virus infection. Thus, under different microenvironments, NK cells play differential roles against viral infections. The kinetics and magnitude of NK cell responses correlate with the distinct roles that NK cells play against influenza virus infections. Thus, our works further our understandings about the complex role of NK cells during influenza virus infection. Copyright © 2016 by The American Association of Immunologists, Inc.

  2. Technical Note: SWIFT - a fast semi-empirical model for polar stratospheric ozone loss

    Science.gov (United States)

    Rex, M.; Kremser, S.; Huck, P.; Bodeker, G.; Wohltmann, I.; Santee, M. L.; Bernath, P.

    2014-07-01

    An extremely fast model to estimate the degree of stratospheric ozone depletion during polar winters is described. It is based on a set of coupled differential equations that simulate the seasonal evolution of vortex-averaged hydrogen chloride (HCl), nitric acid (HNO3), chlorine nitrate (ClONO2), active forms of chlorine (ClOx = Cl + ClO + 2 ClOOCl) and ozone (O3) on isentropic levels within the polar vortices. Terms in these equations account for the chemical and physical processes driving the time rate of change of these species. Eight empirical fit coefficients associated with these terms are derived by iteratively fitting the equations to vortex-averaged satellite-based measurements of HCl, HNO3 and ClONO2 and observationally derived ozone loss rates. The system of differential equations is not stiff and can be solved with a time step of one day, allowing many years to be processed per second on a standard PC. The inputs required are the daily fractions of the vortex area covered by polar stratospheric clouds and the fractions of the vortex area exposed to sunlight. The resultant model, SWIFT (Semi-empirical Weighted Iterative Fit Technique), provides a fast yet accurate method to simulate ozone loss rates in polar regions. SWIFT's capabilities are demonstrated by comparing measured and modeled total ozone loss outside of the training period.

  3. Three years of Swift/BAT Survey of AGN: Reconciling Theory and Observations?

    Energy Technology Data Exchange (ETDEWEB)

    Burlon, D.; /Garching, Max Planck Inst., MPE; Ajello, M.; /SLAC /KIPAC, Menlo Park; Greiner, J.; /Garching, Max Planck Inst., MPE; Comastri, A.; /Muenchen, Tech. U. Universe; Merloni, A.; /Garching, Max Planck Inst., MPE /Muenchen, Tech. U. Universe; Gehrels, N.; /NASA, Goddard

    2011-02-07

    It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still escapes detection. We derive and analyze the absorption distribution using a complete sample of AGN detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGN represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGN is 20{sub -6}{sup +9}%. We proved for the first time (also in the BAT band) that the anti-correlation of the fraction of absorbed AGN and luminosity it tightly connected to the different behavior of the luminosity functions (XLFs) of absorbed and unabsorbed AGN. This points towards a difference between the two subsamples of objects with absorbed AGN being, on average, intrinsically less luminous than unobscured ones. Moreover the XLFs show that the fraction of obscured AGN might also decrease at very low luminosity. This can be successfully interpreted in the framework of a disk cloud outflow scenario as the disappearance of the obscuring region below a critical luminosity. Our results are discussed in the framework of population synthesis models and the origin of the Cosmic X-ray Background.

  4. The diverse broad-band light-curves of Swift GRBs reproduced with the cannonball model

    CERN Document Server

    Dado, Shlomo; De Rújula, A

    2009-01-01

    Two radiation mechanisms, inverse Compton scattering (ICS) and synchrotron radiation (SR), suffice within the cannonball (CB) model of long gamma ray bursts (LGRBs) and X-ray flashes (XRFs) to provide a very simple and accurate description of their observed prompt emission and afterglows. Simple as they are, the two mechanisms and the burst environment generate the rich structure of the light curves at all frequencies and times. This is demonstrated for 33 selected Swift LGRBs and XRFs, which are well sampled from early time until late time and well represent the entire diversity of the broad band light curves of Swift LGRBs and XRFs. Their prompt gamma-ray and X-ray emission is dominated by ICS of glory light. During their fast decline phase, ICS is taken over by SR which dominates their broad band afterglow. The pulse shape and spectral evolution of the gamma-ray peaks and the early-time X-ray flares, and even the delayed optical `humps' in XRFs, are correctly predicted. The canonical and non-canonical X-ra...

  5. Extremal higher spin black holes

    Energy Technology Data Exchange (ETDEWEB)

    Bañados, Máximo [Instituto de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Castro, Alejandra [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, Amsterdam, 1090 GL (Netherlands); Faraggi, Alberto [Instituto de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Jottar, Juan I. [Institut für Theoretische Physik, ETH Zürich,Zürich, CH-8093 (Switzerland)

    2016-04-13

    The gauge sector of three-dimensional higher spin gravities can be formulated as a Chern-Simons theory. In this context, a higher spin black hole corresponds to a flat connection with suitable holonomy (smoothness) conditions which are consistent with the properties of a generalized thermal ensemble. Building on these ideas, we discuss a definition of black hole extremality which is appropriate to the topological character of 3d higher spin theories. Our definition can be phrased in terms of the Jordan class of the holonomy around a non-contractible (angular) cycle, and we show that it is compatible with the zero-temperature limit of smooth black hole solutions. While this notion of extremality does not require supersymmetry, we exemplify its consequences in the context of sl(3|2)⊕sl(3|2) Chern-Simons theory and show that, as usual, not all extremal solutions preserve supersymmetries. Remarkably, we find in addition that the higher spin setup allows for non-extremal supersymmetric black hole solutions. Furthermore, we discuss our results from the perspective of the holographic duality between sl(3|2)⊕sl(3|2) Chern-Simons theory and two-dimensional CFTs with W{sub (3|2)} symmetry, the simplest higher spin extension of the N=2 super-Virasoro algebra. In particular, we compute W{sub (3|2)} BPS bounds at the full quantum level, and relate their semiclassical limit to extremal black hole or conical defect solutions in the 3d bulk. Along the way, we discuss the role of the spectral flow automorphism and provide a conjecture for the form of the semiclassical BPS bounds in general N=2 two-dimensional CFTs with extended symmetry algebras.

  6. Stellar tidal disruption flares provide evidence for a black hole event horizon

    Science.gov (United States)

    Van Velzen, Sjoert

    2017-08-01

    The tidal disruption of a star by a massive black is expected to yield a luminous flare of thermal emission. Optical transient surveys have collected about two dozen similar-looking nuclear transients that are consider examples of these stellar tidal disruption flares (TDFs). However, explaining the observed properties of these events within the tidal disruption paradigm is challenging. For example, there is no consensus on the origin of the optical emission. This theoretical ambiguity leaves open the possibility that the flares we call TDFs are instead due to a completely different process, such a nuclear supernovae or accretion disk instabilities. Fortunately, the number of discovered TDFs recently became large enough to test a fundamental prediction of the stellar tidal disruption paradigm. At high black hole mass (greater than 108 M⊙), the star will be swallowed whole before being disrupted. Using a recently compiled catalog of candidate TDFs with black hole mass measurements, plus a careful treatment of selection effects in this flux-limited sample, we robustly detect a suppression of flares from high-mass black holes. This dearth of observed TDFs from the upper end of the black hole mass distribution is naturally explained by suppression due the event horizon and implies a moderate mean spin of these black holes (a > 0.5). Conversely, if we start by assuming that current TDF candidates are indeed due to stellar tidal disruptions, our sample can be used to constrain the existence of naked singularities.

  7. How to Detect Inclined Water Maser Disks (and Possibly Measure Black Hole Masses)

    Energy Technology Data Exchange (ETDEWEB)

    Darling, Jeremy, E-mail: jdarling@colorado.edu [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)

    2017-03-10

    We describe a method for identifying inclined water maser disks orbiting massive black holes and for potentially using them to measure black hole masses. Owing to the geometry of maser amplification pathways, the minority of water maser disks are observable: only those viewed nearly edge-on have been identified, suggesting that an order of magnitude additional maser disks exist. We suggest that inward-propagating masers are gravitationally deflected by the central black hole, thereby scattering water maser emission out of the disk plane and enabling detection. The signature of an inclined water maser disk would be narrow masers near the systemic velocity that appear to emit from the black hole position, as identified by the radio continuum core. To explore this possibility, we present high-resolution (0.″07–0.″17) Very Large Array line and continuum observations of 13 galaxies with narrow water maser emission and show that three are good inclined-disk candidates (five remain ambiguous). For the best case, CGCG 120−039, we show that the maser and continuum emission are coincident to within 3.5 ± 1.4 pc (6.7 ± 2.7 mas). Subsequent very long baseline interferometric maps can confirm candidate inclined disks and have the potential to show maser rings or arcs that provide a direct measurement of black hole mass, although the mass precision will rely on knowledge of the size of the maser disk.

  8. A New Cosmological Model: Black Hole Universe

    OpenAIRE

    Zhang T. X.

    2009-01-01

    A new cosmological model called black hole universe is proposed. According to this model, the universe originated from a hot star-like black hole with several solar masses, and gradually grew up through a supermassive black hole with billion solar masses to the present state with hundred billion-trillion solar masses by accreting ambient mate- rials and merging with other black holes. The entire space is structured with infinite layers hierarchically. The innermost three laye...

  9. Compensating Scientism through "The Black Hole."

    Science.gov (United States)

    Roth, Lane

    The focal image of the film "The Black Hole" functions as a visual metaphor for the sacred, order, unity, and eternal time. The black hole is a symbol that unites the antinomic pairs of conscious/unconscious, water/fire, immersion/emersion, death/rebirth, and hell/heaven. The black hole is further associated with the quest for…

  10. Black Hole Monodromy and Conformal Field Theory

    NARCIS (Netherlands)

    Castro, A.; Lapan, J.M.; Maloney, A.; Rodriguez, M.J.

    2013-01-01

    The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a nonextremal black hole, and it explains why features of the inner event

  11. On Quantum Contributions to Black Hole Growth

    NARCIS (Netherlands)

    Spaans, M.

    2013-01-01

    The effects of Wheeler’s quantum foam on black hole growth are explored from an astrophysical per- spective. Quantum fluctuations in the form of mini (10−5 g) black holes can couple to macroscopic black holes and allow the latter to grow exponentially in mass on a time scale of 109 years.

  12. Accretion, primordial black holes and standard cosmology

    Indian Academy of Sciences (India)

    Abstract. Primordial black holes evaporate due to Hawking radiation. We find that the evaporation times of primordial black holes increase when accretion of radiation is included. Thus, depending on accretion efficiency, more primordial black holes are existing today, which strengthens the con- jecture that the primordial ...

  13. On black holes and gravitational waves

    CERN Document Server

    Loinger, Angelo

    2002-01-01

    Black holes and gravitational waves are theoretical entities of today astrophysics. Various observed phenomena have been associated with the concept of black hole ; until now, nobody has detected gravitational waves. The essays contained in this book aim at showing that the concept of black holes arises from a misinterpretation of general relativity and that gravitational waves cannot exist.

  14. Extremal black holes in N=2 supergravity

    NARCIS (Netherlands)

    Katmadas, S.

    2011-01-01

    An explanation for the entropy of black holes has been an outstanding problem in recent decades. A special case where this is possible is that of extremal black holes in N=2 supergravity in four and five dimensions. The best developed case is for black holes preserving some supersymmetry (BPS),

  15. A Search for Black Holes and Neutron Stars in the Kepler Field

    Science.gov (United States)

    Orosz, Jerome; Short, Donald; Welsh, William; Windmiller, Gur; Dabney, David

    2018-01-01

    Black holes and neutron stars represent the final evolutionary stages of the most massive stars. In addition to their use as probes into the evolution of massive stars, black holes and neutron stars are ideal laboratories to test General Relativity in the strong field limit. The number of neutron stars and black holes in the Milky Way is not precisely known, but there are an estimated one billion neutron stars in the galaxy based on the observed numbers of radio pulsars. The number of black holes is about 100 million, based on the behavior of the Initial Mass Function at high stellar masses.All of the known steller-mass black holes (and a fair number of neutron stars) are in ``X-ray binaries'' that were discovered because of their luminous X-ray emission. The requirement to be in an X-ray-emitting binary places a strong observational bias on the discovery of stellar-mass black holes. Thus the 21 known black hole binaries represent only the very uppermost tip of the population iceberg.We have conducted an optical survey using Kepler data designed to uncover black holes and neutron stars in both ``quiescent'' X-ray binaries and ``pre-contact'' X-ray binaries. We discuss how the search was conducted, including how potentially interesting light curves were classified and the how variability types were identified. Although we did not find any convincing candidate neutron star or black hole systems, we did find a few noteworthy binary systems, including two binaries that contain low-mass stars with unusually low albedos.

  16. Chandra Catches "Piranha" Black Holes

    Science.gov (United States)

    2007-07-01

    Supermassive black holes have been discovered to grow more rapidly in young galaxy clusters, according to new results from NASA's Chandra X-ray Observatory. These "fast-track" supermassive black holes can have a big influence on the galaxies and clusters that they live in. Using Chandra, scientists surveyed a sample of clusters and counted the fraction of galaxies with rapidly growing supermassive black holes, known as active galactic nuclei (or AGN). The data show, for the first time, that younger, more distant galaxy clusters contained far more AGN than older, nearby ones. Galaxy clusters are some of the largest structures in the Universe, consisting of many individual galaxies, a few of which contain AGN. Earlier in the history of the universe, these galaxies contained a lot more gas for star formation and black hole growth than galaxies in clusters do today. This fuel allows the young cluster black holes to grow much more rapidly than their counterparts in nearby clusters. Illustration of Active Galactic Nucleus Illustration of Active Galactic Nucleus "The black holes in these early clusters are like piranha in a very well-fed aquarium," said Jason Eastman of Ohio State University (OSU) and first author of this study. "It's not that they beat out each other for food, rather there was so much that all of the piranha were able to really thrive and grow quickly." The team used Chandra to determine the fraction of AGN in four different galaxy clusters at large distances, when the Universe was about 58% of its current age. Then they compared this value to the fraction found in more nearby clusters, those about 82% of the Universe's current age. The result was the more distant clusters contained about 20 times more AGN than the less distant sample. AGN outside clusters are also more common when the Universe is younger, but only by factors of two or three over the same age span. "It's been predicted that there would be fast-track black holes in clusters, but we never

  17. Development of candidate rotavirus vaccines.

    Science.gov (United States)

    Bishop, R F

    1993-01-01

    Candidate rotavirus vaccines tested to date have been developed using a 'Jennerian' approach. Strains of bovine and simian rotaviruses that are naturally attenuated for humans have been assessed and found to confer immunity that is serotype specific in a varying proportion of recipients. The spectrum of protection has been widened by developing reassortants in which the bovine or simian gene coding for VP7 (the major outer capsid protein) has been replaced by the corresponding gene from human VP7 types 1, 2, 3 or 4. Once the protective antigen(s) are identified it may be possible to develop subunit vaccines that eliminate side effects sometimes observed with live vaccine candidates.

  18. Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes

    OpenAIRE

    Takahashi, Rohta

    2004-01-01

    Can we determine a spin parameter of a black hole by observation of a black hole shadow in an accretion disk? In order to answer this question, we make a qualitative analysis and a quantitative analysis of a shape and a position of a black hole shadow casted by a rotating black hole on an optically thick accretion disk and its dependence on an angular momentum of a black hole. We have found black hole shadows with a quite similar size and a shape for largely different black hole spin paramete...

  19. The stable problem of the black-hole connected region in the Schwarzschild black hole

    OpenAIRE

    Tian, Guihua

    2005-01-01

    The stability of the Schwarzschild black hole is studied. Using the Painlev\\'{e} coordinate, our region can be defined as the black-hole-connected region(r>2m, see text) of the Schwarzschild black hole or the white-hole-connected region(r>2m, see text) of the Schwarzschild black hole. We study the stable problems of the black-hole-connected region. The conclusions are: (1) in the black-hole-connected region, the initially regular perturbation fields must have real frequency or complex frequen...

  20. A new length scale for quantum gravity: A resolution of the black hole information loss paradox

    Science.gov (United States)

    Singh, Tejinder P.

    We show why and how Compton wavelength and Schwarzschild radius should be combined into one single new length scale, which we call the Compton-Schwarzschild length. Doing so offers a resolution of the black hole information loss paradox, and suggests Planck mass remnant black holes as candidates for dark matter. It also compels us to introduce torsion, and identify the Dirac field with a complex torsion field. Dirac equation and Einstein equations, are shown to be mutually dual limiting cases of an underlying gravitation theory which involves the Compton-Schwarzschild length scale, and includes a complex torsion field.