S. D. Vrtilek

Center for Astrophysics Harvard & Smithsonian

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Bram Boroson

University of South Carolina

J. C. Raymond

Center for Astrophysics Harvard & Smithsonian

T. R. Kallman

Goddard Space Flight Center

Richard McCray

University of California, Berkeley

Michael L. McCollough

Smithsonian Astrophysical Observatory

S. M. Kahn

University of California, Berkeley

G. Fabbiano

Center for Astrophysics Harvard & Smithsonian

Charith Peris

Amazon (United States)

Amy E. Mossman

Center for Astrophysics Harvard & Smithsonian

Dong‐Woo Kim

Center for Astrophysics Harvard & Smithsonian

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Center for Astrophysics Harvard & Smithsonian

125

Smithsonian Astrophysical Observatory

Harvard University

Goddard Space Flight Center

Harvard University Press

Massachusetts Institute of Technology

California Institute of Technology

Max Planck Society

University of California, Berkeley

National Institute for Astrophysics

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Multiwavelength Studies of HER X-1

S. D. Vrtilek J. Truêmper P. Kahabka W. Voges K. Dennerl

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Effects of differing X-ray colors on Color-Color-Intensity diagrams of accreting binaries

AAS/High Energy Astrophysics Division (2019)

S. D. Vrtilek Nazma Islam Boroson Seth Bram Dong‐Woo Kim

Intensity

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Suzaku X-ray Spectra and Pulse Profile Variations during the Superorbital Cycle of LMC X-4

American Astronomical Society Meeting Abstracts #215 (2010)

Li-Wei Hung Ryan C. Hickox Bram Boroson S. D. Vrtilek

We present results from spectral and temporal analyses of Suzaku and RXTE observations of the high-mass X-ray binary LMC X-4. Using the full 13 years of available RXTE/all-sky monitor data, we apply the ANOVA and Lomb Normalized Periodogram methods to obtain an improved superorbital period measurement of 30.32 ± 0.04 days. The phase-averaged X-ray spectra from Suzaku observations during the high state of the superorbital period can be modeled in the 0.6-50 keV band as the combination of a power law with Γ ~ 0.6 and a high-energy cutoff at ~25 keV, a blackbody with kT BB ~ 0.18 keV, and emission lines from Fe Kα, O VIII, and Ne IX (X Lyα). Assuming a distance of 50 kpc, the source has luminosity L X ~ 3 × 1038 erg s–1 in the 2-50 keV band, and the luminosity of the soft (blackbody) component is L BB ~ 1.5 × 1037 erg s–1. The energy-resolved pulse profiles show single-peaked soft (0.5-1 keV) and hard (6-10 keV) pulses but a more complex pattern of medium (2-10 keV) pulses; cross-correlation of the hard with the soft pulses shows a phase shift that varies between observations. We interpret these results in terms of a picture in which a precessing disk reprocesses the hard X-rays and produces the observed soft spectral component, as has been suggested for the similar sources Her X-1 and SMC X-1.

Black-body radiation

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Photoionized Lines in the X-Ray Spectra of SMC X-1

IAU Joint Discussion (2003)

S. D. Vrtilek Bram Boroson Amy B. Leblang

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HST Synthetic Spectral Analysis of U Gem in Early and Late Quiescence: A Heated White Dwarf and Accretion Belt

Astrophysics and space science library (1997)

Fuhua Cheng E. M. Sion K. Horne I. Hubený M. Huang

10.1007/978-94-011-5542-7_53

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Uv Echoes in X-Ray Pulsars: LMC X-4

HST Proposal (1995)

S. D. Vrtilek

X-ray background

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Discovery of Spatial Structures in the X-ray Image of the Crab Nebula

AAS (1999)

M. C. Weisskopf H. L. Marshall J. J. Hester Allyn F. Tennant G. E. Allen

Crab Nebula

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Yet Another Multi wavelength Campaign on Hercules X-1/HZ Herculis

American Astronomical Society Meeting Abstracts #194 (1999)

S. D. Vrtilek Bram Boroson M. Still Hauke Fiedler H. Quaintrell

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Simultaneous [ITAL]Chandra[/ITAL] and [ITAL]Hubble Space Telescope[/ITAL] Observations of SMC X-1

The Astrophysical Journal (2001)

S. D. Vrtilek J. C. Raymond Bram Boroson T. R. Kallman H. Quaintrell

We present first results from simultaneous ultraviolet (Hubble Space Telescope/STIS) and X-ray (Chandra/ACIS) observations of the SMC X-1/SK 160 eclipsing binary system. Observations covering four orbital phases during each of the X-ray high and X-ray low states were taken in 2000 October-November and 2001 April. The ultraviolet P Cygni lines show strong broad absorption near X-ray eclipse and narrow absorption when the X-ray source is in the line of sight. The effect is visible during both the X-ray high and X-ray low states; the UV continuum flux remains roughly constant in spite of more than an order-of-magnitude reduction in X-ray flux, as expected if the X-ray flux reduction is due to occultation of the X-ray source by a precessing disk rather than an intrinsic change in X-ray luminosity. The X-ray spectra are dominated by continuum emission in the X-ray high state. Occultation of the neutron star by the disk during the low state also implies that X-ray emission from the disk surface should be present, and the low-state spectra do show strong emission lines. During eclipse and during the X-ray low state, the continuum emission largely disappears, and we see line emission from O, Ne, Mg, and Fe and possibly from Si and S. The emission lines are consistent with recombination lines from mostly hydrogenic and helium-like species, which could be produced by photoionization in an extended stellar wind.

10.1086/338733

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Concurrent X-ray and optical observations of two dwarf novae during eruption

The Astrophysical Journal (1994)

A. Silber S. D. Vrtilek J. C. Raymond

view Abstract Citations (12) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Concurrent X-Ray and Optical Observations of Two Dwarf Novae during Eruption Silber, A. ; Vrtilek, S. D. ; Raymond, J. C. Abstract The dwarf novae SU UMa and RU Peg were each observed with the ROSAT Observatory during outburst. SU UMa was also observed twice between outbursts. The spectrum of SU UMa during quiescence is well fitted by a 2.1 keV thermal bremsstrahlung model with a Gaussian line at 0.97 keV absorbed by a column density of 1.4 x 1020/sq cm. During the outburst the X-ray count rate dropped by a factor of 3. The outburst spectrum is well fitted to a similar spectrum with a significantly larger absorption. In outburst the mass transfer rate, dot-M, approaches the critical value for the optically thin/thick transition predicted by theoretical models of the boundary layer while the X-ray emission remains optically thin. The best-fit model to the outburst spectrum of RU Peg is a 4.9 keV thermal bremsstrahlung plus a line at 0.89 keV absorbed by a column density of 2.8 x 1020/sq cm. The column density is consistent with the upper limit determined for interstellar absorption. The boundary layer at outburst is expected to be optically thick based on the value of dot-M determined from the IUE spectra. There are no ROSAT observations of RU Peg between outbursts, but the flux detected by ROSAT is a factor of 10 lower than that seen with the Einstein Observatory, probably during quiescence. For both CVs the X-ray flux from the boundary layer significantly decreases at the same time that the optical-UV flux greatly increases. We suggest that during outburst most of the boundary layer energy is carried away as kinetic energy of the wind. Publication: The Astrophysical Journal Pub Date: April 1994 DOI: 10.1086/174027 Bibcode: 1994ApJ...425..829S Keywords: Cataclysmic Variables; Dwarf Novae; Stellar Models; X Ray Sources; Bremsstrahlung; Iue; Mass Transfer; Proportional Counters; Rosat Mission; Stellar Mass Ejection; Stellar Winds; Astrophysics full text sources ADS | data products SIMBAD (4) MAST (1) INES (1) HEASARC (1)

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10.1086/174027

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