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Full-Text Articles in Physical Sciences and Mathematics
Late Delivery Of Nitrogen To The Earth, Cheng Chen, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio
Late Delivery Of Nitrogen To The Earth, Cheng Chen, Jeremy L. Smallwood, Rebecca G. Martin, Mario Livio
Physics & Astronomy Faculty Research
Atmospheric nitrogen may be a necessary ingredient for the habitability of a planet as its presence helps to prevent water loss from a planet. The present-day nitrogen isotopic ratio, N-15/N-14, in the Earth's atmosphere is a combination of the primitive Earth's ratio and the ratio that might have been delivered in comets and asteroids. Asteroids have a nitrogen isotopic ratio that is close to the Earth's. This indicates either a similar formation environment to the Earth or that the main source of nitrogen was delivery by asteroids. However, according to geological records, the Earth's atmosphere could have been enriched in …
A New Look At T Tauri Star Forbidden Lines: Mhd-Driven Winds From The Inner Disk, Min Fang, Ilaria Pascucci, Suzan Edwards, Uma Gorti, Andrea Banzatti, Mario Flock, Patrick Hartigan, Gregory J. Herczeg, Andrea K. Dupree
A New Look At T Tauri Star Forbidden Lines: Mhd-Driven Winds From The Inner Disk, Min Fang, Ilaria Pascucci, Suzan Edwards, Uma Gorti, Andrea Banzatti, Mario Flock, Patrick Hartigan, Gregory J. Herczeg, Andrea K. Dupree
Astronomy: Faculty Publications
Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. We report the first high-resolution (∆v ∼ 6 km s−1 ) analysis of [S II] λ4068, [O I] λ5577, and [O I] λ6300 lines from a sample of 48 T Tauri stars. Following Simon et al. (2016), we decompose them into three kinematic components: a high-velocity component (HVC) associated with jets, and a low-velocity narrow (LVC-NC) and broad (LVC-BC) components. We confirm previous findings that many LVCs are blueshifted by more than 1.5 km s−1 thus most likely trace a …
A Study Of Hα Line Profile Variations In Β Lyr, Richard Ignace, Sharon K. Gray, Macno A. Magno, Gary D. Henson, Derek Massa
A Study Of Hα Line Profile Variations In Β Lyr, Richard Ignace, Sharon K. Gray, Macno A. Magno, Gary D. Henson, Derek Massa
ETSU Faculty Works
We examine over 160 archival Hα spectra from the Ritter Observatory for the interacting binary β Lyr obtained between 1996 and 2000. The emission is characteristically double-peaked, but asymmetric, and with an absorption feature that is persistently blueshifted. Using a set of simplifying assumptions, phase varying emission line profiles are calculated for Hα formed entirely in a Keplerian disk, and separately for the line formed entirely from an off-center bipolar flow. However, a dynamic spectrum of the data indicates that the blueshifted feature is not always present, and the data are even suggestive of a drift of the …
Upper Limits On Gravitational Waves From Scorpius X-1 From A Model-Based Cross-Correlation Search In Advanced Ligo Data, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, B. Hughey, J. W. W. Pratt, E. Schmidt, S. G. Schwalbe, M. J. Szczepańczyk, M. Zanolin, Et Al.
Upper Limits On Gravitational Waves From Scorpius X-1 From A Model-Based Cross-Correlation Search In Advanced Ligo Data, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, B. Hughey, J. W. W. Pratt, E. Schmidt, S. G. Schwalbe, M. J. Szczepańczyk, M. Zanolin, Et Al.
Publications
We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25–$2000\,\mathrm{Hz}$, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and …
Tracing Slow Winds From T Tauri Stars Via Low-Velocity Forbidden Line Emission, M. N. Simon, I. Pascucci, Suzan Edwards, W. Feng, U. Gorti, D. Hollenbach, E. Rigliaco, J. T. Keane
Tracing Slow Winds From T Tauri Stars Via Low-Velocity Forbidden Line Emission, M. N. Simon, I. Pascucci, Suzan Edwards, W. Feng, U. Gorti, D. Hollenbach, E. Rigliaco, J. T. Keane
Astronomy: Faculty Publications
Using Keck/HIRES spectra (Δ v ∼ 7 km s−1) we analyze forbidden lines of [O I] 6300 Å, [O I] 5577 Å and [S II] 6731 Å from 33 T Tauri stars covering a range of disk evolutionary stages. After removing a high-velocity component (HVC) associated with microjets, we study the properties of the low-velocity component (LVC). The LVC can be attributed to slow disk winds that could be magnetically (magnetohydrodynamic) or thermally (photoevaporative) driven. Both of these winds play an important role in the evolution and dispersal of protoplanetary material. LVC emission is seen in all 30 stars with …
Discovery Of The Candidate Off-Nuclear Ultrasoft Hyper-Luminous X-Ray Source 3xmm J141711.1+522541, Dacheng Lin, Eleazar Carrasco, Natalie Webb, Jimmy Irwin, Renato Dupke, Aaron Romanowsky, Enrico Ramirez-Ruiz, Jay Strader, Jeroen Homan, Didier Barret, Olivier Godet
Discovery Of The Candidate Off-Nuclear Ultrasoft Hyper-Luminous X-Ray Source 3xmm J141711.1+522541, Dacheng Lin, Eleazar Carrasco, Natalie Webb, Jimmy Irwin, Renato Dupke, Aaron Romanowsky, Enrico Ramirez-Ruiz, Jay Strader, Jeroen Homan, Didier Barret, Olivier Godet
Faculty Publications
No abstract provided.
On The Disk Wind Mass Loss Rates In Qsos, Nicolas A. Pereyra
On The Disk Wind Mass Loss Rates In Qsos, Nicolas A. Pereyra
Physics and Astronomy Faculty Publications and Presentations
We derive here a relatively simple expression for the total wind mass loss rates in QSOs within the accretion disk wind scenario. We show that the simple expression derived here for QSO disk wind mass loss rate is in a very good agreement with the more “exact” values obtained through significantly more complex and detailed numerically intensive 2.5D time-dependent simulations. Additionally we show that for typical QSO parameters, the disk itself will be emitting mostly in the UV/optical spectrum, in turn implying that the X-ray emission from QSOs likely is produced through some physical mechanism acting at radii smaller than …
Probing Stellar Accretion With Mid-Infrared Hydrogen Lines, Elisabetta Rigliaco, Ilaria Pascucci, Gaspard Duchene, Suzan Edwards, D. R. Ardila, C. Grady, Ignacio Mendigutía, Benjamín Montesinos, Gijs D. Mulders, Joan R. Najita, J. Carpenter, Elise Furlan, Uma Gorti, Rowin Meijerink, M. R. Meyer
Probing Stellar Accretion With Mid-Infrared Hydrogen Lines, Elisabetta Rigliaco, Ilaria Pascucci, Gaspard Duchene, Suzan Edwards, D. R. Ardila, C. Grady, Ignacio Mendigutía, Benjamín Montesinos, Gijs D. Mulders, Joan R. Najita, J. Carpenter, Elise Furlan, Uma Gorti, Rowin Meijerink, M. R. Meyer
Astronomy: Faculty Publications
In this paper we investigate the origin of the mid-infrared (IR) hydrogen recombination lines for a sample of 114 disks in different evolutionary stages (full, transitional, and debris disks) collected from the Spitzer archive. We focus on the two brighter H I lines observed in the Spitzer spectra, the H I (7-6) at 12.37 μm and the H I (9-7) at 11.32 μm. We detect the H I (7-6) line in 46 objects, and the H I (9-7) in 11. We compare these lines with the other most common gas line detected in Spitzer spectra, the [Ne II] at 12.81 …
Multi-Wavelength Coverage Of State Transitions In The New Black Hole X-Ray Binary Swift J1910.2-0546, N. Degenaar, D. Maitra, E. M. Cackett, M. T. Reynolds, J M. Miller, R. C. Reis, A L. King, K. Gültekin, C D. Bailyn, M M. Buxton, R K. D Macdonald, A. C. Fabian, D B. Fox, E. S. Rykoff
Multi-Wavelength Coverage Of State Transitions In The New Black Hole X-Ray Binary Swift J1910.2-0546, N. Degenaar, D. Maitra, E. M. Cackett, M. T. Reynolds, J M. Miller, R. C. Reis, A L. King, K. Gültekin, C D. Bailyn, M M. Buxton, R K. D Macdonald, A. C. Fabian, D B. Fox, E. S. Rykoff
Physics and Astronomy Faculty Research Publications
Understanding howblack holes accrete and supply feedback to their environment is one of the outstanding challenges of modern astrophysics. Swift J1910.2–0546 is a candidate black hole low-mass X-ray binary that was discovered in 2012 when it entered an accretion outburst. To investigate the binary configuration and the accretion morphology, we monitored the evolution of the outburst for ≃3 months at X-ray, UV, optical (B,V,R,I), and near-infrared (J,H,K) wavelengths using Swift and SMARTS. The source evolved from a hard to a soft X-ray spectral state with a relatively cold accretion disk that peaked at ≃0.5 keV. A Chandra/HETG spectrum obtained during …
Interpreting Near Infrared Hydrogen Line Ratios In T Tauri Stars, Suzan Edwards
Interpreting Near Infrared Hydrogen Line Ratios In T Tauri Stars, Suzan Edwards
Astronomy: Faculty Publications
In accreting young stars, one of the prominent spectral features in the near-infrared is the Paschen and Brackett series in emission. We examine hydrogen line ratios for 16 classical T Tauri stars from SpeX spectra and assess the trends with veiling and accretion. The observed line ratios are compared with two theoretical models for line formation: (1) Baker & Menzel’s Case B for radiative ionization and recombination and (2) a set of local line excitation calculations designed to replicate the conditions in T Tauri winds and magnetic accretion columns (KF). While the comparison between Case B and observed line ratios …
Broad Iron Lines In Neutrons Stars: Dynamical Broadening Or Wind Scattering?, E. M. Cackett, Jon M. Miller
Broad Iron Lines In Neutrons Stars: Dynamical Broadening Or Wind Scattering?, E. M. Cackett, Jon M. Miller
Physics and Astronomy Faculty Research Publications
Broad iron emission lines are observed in many accreting systems from black holes in active galactic nuclei and X-ray binaries to neutron star low-mass X-ray binaries. The origin of the line broadening is often interpreted as due to dynamical broadening and relativistic effects. However, alternative interpretations have been proposed, included broadening due to Compton scattering in a wind or accretion disk atmosphere. Here we explore the observational signatures expected from broadening in a wind, in particular that the iron line width should increase with an increase in the column density of the absorber (due to an increase in the number …
Accretion Variability Of Herbig Ae/Be Stars Observed By X-Shooter Hd 31648 And Hd 163296, I Mendigutia, Sean D. Brittain, C Eiroa, G Meeus, B Montesinos, A Mora, J Muzerolle, R D. Oudmaijer, E Rigliaco
Accretion Variability Of Herbig Ae/Be Stars Observed By X-Shooter Hd 31648 And Hd 163296, I Mendigutia, Sean D. Brittain, C Eiroa, G Meeus, B Montesinos, A Mora, J Muzerolle, R D. Oudmaijer, E Rigliaco
Publications
This work presents X-Shooter/Very Large Telescope spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of 12 ultraviolet, optical, and near-infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean …
Understanding The Origin Of The [Oi] Low-Velocity Component From T Tauri Stars, Elisabetta Rigliaco, Ilaria Pascucci, Uma Gorti, Suzan Edwards, D. Hollenbach
Understanding The Origin Of The [Oi] Low-Velocity Component From T Tauri Stars, Elisabetta Rigliaco, Ilaria Pascucci, Uma Gorti, Suzan Edwards, D. Hollenbach
Astronomy: Faculty Publications
The formation time, masses, and location of planets are strongly impacted by the physical mechanisms that disperse protoplanetary disks and the timescale over which protoplanetary material is cleared out. Accretion of matter onto the central star, protostellar winds/jets, magnetic disk winds, and photoevaporative winds operate concurrently. Hence, disentangling their relative contribution to disk dispersal requires identifying diagnostics that trace different star–disk environments. Here, we analyze the low-velocity component (LVC) of the oxygen optical forbidden lines, which is found to be blueshifted by a few km s−1 with respect to the stellar velocity. We find that the [O i] LVC …
Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian
Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian
Physics and Astronomy Faculty Research Publications
Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe Kα line peaks, lags the bands at lower …
A Soft X-Ray Reverberation Lag In The Agn Eso 113-G010, E. M. Cackett, A. C. Fabian, A. Zogbhi, E. Kara, C. Reynolds, P. Uttley
A Soft X-Ray Reverberation Lag In The Agn Eso 113-G010, E. M. Cackett, A. C. Fabian, A. Zogbhi, E. Kara, C. Reynolds, P. Uttley
Physics and Astronomy Faculty Research Publications
Reverberation lags have recently been discovered in a handful of nearby, variable active galactic nuclei (AGNs). Here, we analyze a ~100 ks archival XMM-Newton observation of the highly variable AGN, ESO 113-G010, in order to search for lags between hard, 1.5-4.5 keV, and soft, 0.3-0.9 keV, energy X-ray bands. At the lowest frequencies available in the light curve (lsim 1.5 × 10-4 Hz), we find hard lags where the power-law-dominated hard band lags the soft band (where the reflection fraction is high). However, at higher frequencies in the range (2-3) × 10-4 Hz we find a soft lag …
Evidence Of Light-Bending Effects And Its Implication For Spectral State Transitions, R. C. Reis, J. M. Miller, M. T. Reynolds, A. C. Fabian, D. J. Walton, E. Cackett, J. F. Steiner
Evidence Of Light-Bending Effects And Its Implication For Spectral State Transitions, R. C. Reis, J. M. Miller, M. T. Reynolds, A. C. Fabian, D. J. Walton, E. Cackett, J. F. Steiner
Physics and Astronomy Faculty Research Publications
It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal changes has not yet emerged. We present results from a systematic analysis of Rossi X-Ray Timing Explorer observations of the stellar-mass black hole binary XTE J1650-500. All spectra with significant hard X-ray detections were fit using a self-consistent, relativistically blurred disk reflection model suited to high ionization regimes. Importantly, we find evidence that both the spectral and timing properties …
Regulation Of Black Hole Winds And Jets Across The Mass Scale, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, K. Gültekin, E. M. Cackett, S. W. Allen, D. Proga, T. R. Kallman
Regulation Of Black Hole Winds And Jets Across The Mass Scale, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, K. Gültekin, E. M. Cackett, S. W. Allen, D. Proga, T. R. Kallman
Physics and Astronomy Faculty Research Publications
We present a study of the mechanical power generated by both winds and jets across the black hole mass scale. We begin with the study of ionized X-ray winds and present a uniform analysis using Chandra grating spectra. The high-quality grating spectra facilitate the characterization of the outflow velocity, ionization, and column density of the absorbing gas. We find that the kinetic power of the winds, derived from these observed quantities, scales with increasing bolometric luminosity as log (L wind, 42/Cv ) = (1.58 ± 0.07)log (L Bol, 42) - (3.19 ± 0.19). This suggests that supermassive …
The Disk-Wind-Jet Connection In The Black Hole H 1743-322, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, A. L. King, T. R. Kallman, E. M. Cackett, M. Van Der Klis, D. T. H. Steeghs
The Disk-Wind-Jet Connection In The Black Hole H 1743-322, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, A. L. King, T. R. Kallman, E. M. Cackett, M. Van Der Klis, D. T. H. Steeghs
Physics and Astronomy Faculty Research Publications
X-ray disk winds are detected in spectrally soft, disk-dominated phases of stellar-mass black hole outbursts. In contrast, compact, steady, relativistic jets are detected in spectrally hard states that are dominated by non-thermal X-ray emission. Although these distinctive outflows appear to be almost mutually exclusive, it is possible that a disk wind persists in hard states but cannot be detected via X-ray absorption lines owing to very high ionization. Here, we present an analysis of a deep, 60 ks Chandra/HETGS observation of the black hole candidate H 1743-322 in the low/hard state. The spectrum shows no evidence of a disk wind, …
Contribution Of The Accretion Disk, Hot Corona, And Obscuring Torus To The Luminosity Of Seyfert Galaxies: Integral And Spitzer Observations, S. Sazonov, S. P. Willner, A. D. Goulding, R. C. Hickox
Contribution Of The Accretion Disk, Hot Corona, And Obscuring Torus To The Luminosity Of Seyfert Galaxies: Integral And Spitzer Observations, S. Sazonov, S. P. Willner, A. D. Goulding, R. C. Hickox
Dartmouth Scholarship
We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spitzer mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei (AGNs) from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal-to-noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L 15 μm∝L0.74 ± 0.06 HX. Assuming that the observed MIR emission is radiation …
A Four-Year Xmm-Newton/Chandra Monitoring Campaign Of The Galactic Centre: Analysing The X-Ray Transients, N. Degenaar, R. Wijnands, E. M. Cackett, J. Homan, J. J. M. In 'T Zand, E. Kuulkers, T. J. Maccarone, M. Van Der Klis
A Four-Year Xmm-Newton/Chandra Monitoring Campaign Of The Galactic Centre: Analysing The X-Ray Transients, N. Degenaar, R. Wijnands, E. M. Cackett, J. Homan, J. J. M. In 'T Zand, E. Kuulkers, T. J. Maccarone, M. Van Der Klis
Physics and Astronomy Faculty Research Publications
We report on the results of a four-year long X-ray monitoring campaign of the central 1.2 square degrees of our Galaxy, performed with Chandra and XMM-Newton between 2005 and 2008. Our study focuses on the properties of transient X-ray sources that reach 2-10 keV luminosities of LX ≳ 1034 erg s-1 for an assumed distance of 8 kpc. There are 17 known X-ray transients within the field of view of our campaign, eight of which were detected in outburst during our observations: the transient neutron star low-mass X-ray binaries GRS 1741-2853, AX J1745.6-2901, SAX J1747.0-2853, KS 1741-293 …
On The Role Of The Accretion Disk In Black Hole Disk-Jet Connections, J. M. Miller, G. G. Pooley, A. C. Fabian, M. A. Nowak, R. C. Reis, E. M. Cackett, K. Pottschmidt, J. Wilms
On The Role Of The Accretion Disk In Black Hole Disk-Jet Connections, J. M. Miller, G. G. Pooley, A. C. Fabian, M. A. Nowak, R. C. Reis, E. M. Cackett, K. Pottschmidt, J. Wilms
Physics and Astronomy Faculty Research Publications
Models of jet production in black hole systems suggest that the properties of the accretion disk—such as its mass accretion rate, inner radius, and emergent magnetic field—should drive and modulate the production of relativistic jets. Stellar-mass black holes in the "low/hard" state are an excellent laboratory in which to study disk-jet connections, but few coordinated observations are made using spectrometers that can incisively probe the inner disk. We report on a series of 20 Suzaku observations of Cygnus X-1 made in the jet-producing low/hard state. Contemporaneous radio monitoring was done using the Arcminute MicroKelvin Array radio telescope. Two important and …
A Comparison Of Broad Iron Emission Lines In Archival Data Of Neutron Star Low-Mass X-Ray Binaries, Edward M. Cackett, Jon M. Miller, Rubens C. Reis, Andrew C. Fabian, Didier Barret
A Comparison Of Broad Iron Emission Lines In Archival Data Of Neutron Star Low-Mass X-Ray Binaries, Edward M. Cackett, Jon M. Miller, Rubens C. Reis, Andrew C. Fabian, Didier Barret
Physics and Astronomy Faculty Research Publications
Relativistic X-ray disklines have been found in multiple neutron star low-mass X-ray binaries, in close analogy with black holes across the mass scale. These lines have tremendous diagnostic power and have been used to constrain stellar radii and magnetic fields, often finding values that are consistent with independent timing techniques. Here, we compare CCD-based data from Suzaku with Fe K line profiles from archival data taken with gas-based spectrometers. In general, we find good consistency between the gas-based line profiles from EXOSAT, BeppoSAX, and RXTE and the CCD data from Suzaku, demonstrating that the broad profiles seen are intrinsic to …
Swift Follow-Up Observations Of Unclassified Asca Sources, N. Degenaar, R. L. C. Starling, P. A. Evans, A. P. Beardmore, D. N. Burrows, E. M. Cackett, S. Campana, D. Grupe, A. Moretti, C. Pagani, K. L. Page, V. La Parola, R. Wijnands
Swift Follow-Up Observations Of Unclassified Asca Sources, N. Degenaar, R. L. C. Starling, P. A. Evans, A. P. Beardmore, D. N. Burrows, E. M. Cackett, S. Campana, D. Grupe, A. Moretti, C. Pagani, K. L. Page, V. La Parola, R. Wijnands
Physics and Astronomy Faculty Research Publications
We present Swift follow-up observations of a sample of 35 unclassified faint X-ray sources drawn from the ASCA Galactic centre and Galactic plane surveys. Our short, pointed XRT observations allow detections down to a limiting 0.3-10 keV flux of FX ~ 10-13 erg cm-2 s-1, which translates into a luminosity of LX ~ 1033 erg s-1 for an assumed distance of D = 8 kpc. The brightest source in our sample reaches a maximum 0.3-10 keV luminosity of LX ~ 2 × 1036 (D/8 kpc)2 erg s-1 during …
A Chandra Survey Of Supermassive Black Holes With Dynamical Mass Measurements, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
A Chandra Survey Of Supermassive Black Holes With Dynamical Mass Measurements, Kayhan Gültekin, Edward M. Cackett, Jon M. Miller, Tiziana Di Matteo, Sera Markoff, Douglas O. Richstone
Physics and Astronomy Faculty Research Publications
We present Chandra observations of 12 galaxies that contain supermassive black holes (SMBHs) with dynamical mass measurements. Each galaxy was observed for 30 ks and resulted in a total of 68 point-source detections in the target galaxies including SMBH sources, ultraluminous X-ray sources (ULXs), and extragalactic X-ray binaries. Based on our fits of the X-ray spectra, we report fluxes, luminosities, Eddington ratios, and slope of the power-law spectrum. Normalized to the Eddington luminosity, the 2-10 keV band X-ray luminosities of the SMBH sources range from 10-8 to 10-6, and the power-law slopes are centered at ~2 with …
Ionized Reflection Spectra From Accretion Disks Illuminated By X-Ray Pulsars, D. R. Ballantyne, J. D. Purvis, R. G. Strausbaugh, R. C. Hickox
Ionized Reflection Spectra From Accretion Disks Illuminated By X-Ray Pulsars, D. R. Ballantyne, J. D. Purvis, R. G. Strausbaugh, R. C. Hickox
Dartmouth Scholarship
X-ray reflection signatures are observed around multiple classes of accreting compact objects. Modelling these features yield important constraints on the physics of accretion disks, motivating the development of X-ray reflection models appropriate for a variety of systems and illumination conditions. Here, constant density ionized X-ray reflection models are presented for a disk irradiated with a very hard power-law X-ray spectrum (\Gamma < 1) and a variable high-energy cutoff. These models are then applied to the Suzaku data of the accreting X-ray pulsar LMC X-4, where very good fits are obtained with a highly ionized reflector responsible for both the broad Fe K line and the soft excess. The ionized reflector shows strong evidence for significant Doppler broadening and is redshifted by ~10^4 km/s. These features indicate that the reflecting material is associated with the complex dynamics occurring at the inner region of the magnetically-truncated accretion disk. Thus, reflection studies of X-ray pulsar spectra may give important insights into the accretion physics at the magnetospheric radius.
An Extreme X-Ray Disk Wind In The Black Hole Candidate Igr J17091-3624, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, T. R. Kallman, D. Maitra, E. M. Cackett, M. P. Rupen
An Extreme X-Ray Disk Wind In The Black Hole Candidate Igr J17091-3624, A. L. King, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, T. R. Kallman, D. Maitra, E. M. Cackett, M. P. Rupen
Physics and Astronomy Faculty Research Publications
Chandra spectroscopy of transient stellar-mass black holes in outburst has clearly revealed accretion disk winds in soft, disk-dominated states, in apparent anti-correlation with relativistic jets in low/hard states. These disk winds are observed to be highly ionized, dense, and to have typical velocities of ~1000 km s-1 or less projected along our line of sight. Here, we present an analysis of two Chandra High Energy Transmission Grating spectra of the Galactic black hole candidate IGR J17091-3624 and contemporaneous Expanded Very Large Array (EVLA) radio observations, obtained in 2011. The second Chandra observation reveals an absorption line at 6.91 ± …
Veritas Observations Of The Unusual Extragalactic Transient Swift J164449.3+573451, P. T. Reynolds, Et Al
Veritas Observations Of The Unusual Extragalactic Transient Swift J164449.3+573451, P. T. Reynolds, Et Al
Physical Sciences Publications
We report on very high energy (>100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the Swift Observatory and later detected by multiple radio, optical, and X-ray observatories. A total exposure of 28 hr was obtained on Swift J164449.3+573451 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) during 2011 March 28-April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of 1.4 × 10–12 erg cm–2 s–1 (99% confidence level). We also present time-resolved upper limits and use a …
The Variable Quiescent X-Ray Emission Of The Neutron Star Transient Xte J1701-462, Joel K. Fridriksson, Jeroen Homan, Rudy Wijnands, Edward M. Cackett, Diego Altamirano, Nathalie Degenaar, Edward F. Brown, Mariano Méndez, Tomaso M. Belloni
The Variable Quiescent X-Ray Emission Of The Neutron Star Transient Xte J1701-462, Joel K. Fridriksson, Jeroen Homan, Rudy Wijnands, Edward M. Cackett, Diego Altamirano, Nathalie Degenaar, Edward F. Brown, Mariano Méndez, Tomaso M. Belloni
Physics and Astronomy Faculty Research Publications
We present the results of continued monitoring of the quiescent neutron star low-mass X-ray binary XTE J1701-462 with Chandra and Swift. A new Chandra observation from 2010 October extends our tracking of the neutron star surface temperature from ≃ 800 days to ≃ 1160 days since the end of an exceptionally luminous 19 month outburst. This observation indicates that the neutron star crust may still be slowly cooling toward thermal equilibrium with the core; another observation further into quiescence is needed to verify this. The shape of the overall cooling curve is consistent with that of a broken power law, …
A Fast X-Ray Disk Wind In The Transient Pulsar Igr J17480-2446 In Terzan 5, Jon M. Miller, Dipankar Maitra, Edward M. Cackett, Sudip Bhattacharyya, Tod E. Strohmayer
A Fast X-Ray Disk Wind In The Transient Pulsar Igr J17480-2446 In Terzan 5, Jon M. Miller, Dipankar Maitra, Edward M. Cackett, Sudip Bhattacharyya, Tod E. Strohmayer
Physics and Astronomy Faculty Research Publications
Accretion disk winds are revealed in Chandra gratings spectra of black holes. The winds are hot and highly ionized (typically composed of He-like and H-like charge states) and show modest blueshifts. Similar line spectra are sometimes seen in "dipping" low-mass X-ray binaries (LMXBs), which are likely viewed edge-on; however, that absorption is tied to structures in the outer disk, and blueshifts are not typically observed. Here, we report the detection of blueshifted He-like Fe XXV (3100 ± 400 km s-1) and H-like Fe XXVI (1000 ± 200 km s-1) absorption lines in a Chandra/HETG spectrum of …
Characterizing The Iyj Excess Continuum Emission In T Tauri Stars, William J. Fischer, Suzan Edwards, Lynne A. Hillenbrand, John Kwan
Characterizing The Iyj Excess Continuum Emission In T Tauri Stars, William J. Fischer, Suzan Edwards, Lynne A. Hillenbrand, John Kwan
Astronomy: Faculty Publications
We present the first characterization of the excess continuum emission of accreting T Tauri stars between optical and near-infrared wavelengths. With nearly simultaneous spectra from 0.48 to 2.4μm acquired with HIRES and NIRSPEC on Keck and SpeX on the Infrared Telescope Facility, we find significant excess continuum emission throughout this region, including the I, Y, and J bands, which are usually thought to diagnose primarily photospheric emission. The IYJ excess correlates with the excess in the V band, attributed to accretion shocks in the photosphere, and the excess in the K band, attributed to dust in the inner …