High-Resolution Chandra HETGS and Rossi X-Ray Timing Explorer Observations of GRS 1915+105: A Hot Disk Atmosphere and Cold Gas Enriched in Iron and Silicon

By Julia C. Lee, C. Reynolds, Ronald A. Remillard, N. Schulz, Eric G. Blackman, A. C. Fabian. 2001

166 citations recorded by the source corpus.

The time-averaged 30 ks Chandra AO1 High Energy Transmission Grating Spectrometer observation of the microquasar GRS 1915+105 in the low hard state reveals for the first time in this source neutral K absorption edges from iron, silicon, magnesium, and sulphur. Ionized resonance (r) absorption from H- and He-like species of Fe (XXV, XXVI) and possibly Ca XX are also seen as well as possible emission from neutral Fe Kα and ionized Fe XXV (forbidden or the resonance emission component of a P Cygni profile). We report the tentative detection of the first astrophysical signature of X-ray absorption fine structure in the photoelectric edge of Si (and possibly Fe and Mg) attributed to material in grains. The large column densities measured from the neutral edges reveal anomalous Si and Fe abundances and illustrate the importance of high-resolution X-ray measurements for assessing material that surrounds bright X-ray sources, especially if depletion onto grains plays a prominent role. Scenarios for which the anomalous abundances can be attributed to surrounding cold material associated with GRS 1915+105 and/or for which the enrichment may signify either a highly unusual supernova/hypernova or external supernova activity local to the binary are discussed. We attribute the ionized features to a hot disk, disk wind, or corona environment. Based on H- and He-like Fe (XXV, XXVI), we estimate constraints on the ionization parameter (log ξ ≳ 4.15), temperature (T > 2.4 × 106 K), and hydrogen equivalent number density (n ≳ 1012 cm-3) for this region. Variability studies with the simultaneous RXTE data show that the light-curve count rate tracks the changes in the disk blackbody as well as the power-law flux, with the most significant variations observed in the former. The Chandra data show spectral changes that also track the behavior of the light curve and may point to changes in both the ionizing flux and density of the absorber. A 3.69 Hz quasi-periodic oscillation and weak first harmonic are seen in the RXTE data.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/351e0cb90dc7b3a9fe90b6f1923ae6e026d83398

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Citations in the corpus

Simultaneous Chandra and RXTE Spectroscopy of the Microquasar H1743–322: Clues to Disk Wind and Jet Formation from a Variable Ionized Outflow (2004, background): “In the recent past , similar absorption lines have been detected in the microquasars GRO J1655 40 (Ueda et al. 1998) andGRS 1915+ 105 (Kotani et al. 2000) with the Advanced Satellite for Cosmology and Astrophysics (ASCA) and in GRS 1915+105 with Chandra (Lee et al. 2002).”
A Massive X-Ray Outflow from the Quasar PDS 456 (2003, background): “We also note that strong iron K absorption has also been observed in the narrow-line Seyfert 1 galaxies 1H 0707 495 and IRAS 13324 3809 (Boller et al. 2002, 2003) and also in some X-ray binaries, e.g., GRS 1915 105 (Lee et al. 2002), GX 13 1 (Sidoli et al. 2002), and X 1624 490 (Parmar et al. 2002).”
A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143 (2003, background): “In the latter respect it may be instructive to note that ionised resonance absorption lines of Fe XXV and XXVI are clearly seen in the Chandra HETGS spectrum of the (much brighter) microquasar GRS 1915+105 (Lee et al. 2002).”
Ubiquitous equatorial accretion disc winds in black hole soft states (2012, background): “Assuming that the Fe XXV and Fe XXVI absorption lines are unsaturated and are on the linear part of the curve of growth, we can estimate the Fe XXV and Fe XXVI ion abundances (see formula 1 of Lee et al. 2002).”
The Accretion Disk Wind in the Black Hole GRO J1655–40 (2008, background): “GRS 1915+105 is seen at a high inclination, like GRO J1655−40, and a highly ionized wind is seen in this source (Lee et al. 2002).”
Spectral changes during dipping in low-mass X-ray binaries due to highly-ionized absorbers (2005, background): “These features were first detected from the micro-quasars GRO J1655−40 (Ueda et al. 1998; Yamaoka et al. 2001) and GRS 1915+105 (Kotani et al. 2000; Lee et al. 2002).”
WATCHDOG: A COMPREHENSIVE ALL-SKY DATABASE OF GALACTIC BLACK HOLE X-RAY BINARIES (2015, background): “…accretion disk have been observed (exclusively) in the soft accretion state (Neilsen & Lee 2009; Ponti et al. 2012) of many Galactic BH systems (Lee et al. 2002; Miller et al. 2004, 2006c,b, 2008; King et al. 2012b; Neilsen & Homan 2012; Diaz Trigo et al. 2014), indicating that these systems…”
X-Ray Properties of Black-Hole Binaries (2006, background): “Finally, high-resolution grating spectra of BHBs sometimes reveal hot gas that is local to the binary system (e.g., Lee et al 2002).”