Spectrum Synthesis Modeling of the X-Ray Spectrum of Gro J1655-40 Taken During the 2005 Outburst

Abstract

The spectrum from the black hole X-ray transient GRO J1655-40. obtained using the Chandra High Energy Transmission Grating (HETG) in 2005 is notable as a laboratory for the study of warm absorbers, and for the presence of many lines from odd-Z elements between Na and Co (and Ti and Cr) not previously observed in X-rays. We present synthetic spectral models which can be used to constrain these element abundances and other parameters describing the outflow from the warm absorber in this object. We present results of fitting to the spectrum using various tools and techniques, including automated line fitting, phenomenological models, and photoionization modeling. We show that the behavior of the curves of growth of lines from H-like and Li-like ions indicate that the lines are either saturated or affected by filling-in from scattered or a partially covered continuum source. We confirm the conclusion of previous work by Miller et al. (2006) andMiller et al. (2008) which shows that the ionization conditions are not consistent with wind driving due to thermal expansion. The spectrum provides the opportunity to measure abundances for several elements not typically observable in the X-ray band. These show a pattern of enhancement for iron peak elements, and solar or sub-solar values for elements lighter than calcium. Models show that this is consistent with enrichment by a core-collapse supernova. We discuss the implications of these values for the evolutionary history of this system.

XMM-Newtonobservations of GX 13 + 1: correlation between photoionised absorption and broad line emission

“…These blueshifts seem too large, compared to the shifts of ∼400 km s −1 obtained by Ueda et al (2004) for GX 13+1 and of ∼300-1600 km s −1 in microquasars (e.g. Kallman et al 2009;Ueda et al 2009;see however Miller et al 2011 for a recently reported blueshift of 3100 ± 400 km s −1 in a Chandra A50, page 12 of 17 HETGS observation of IGR J17480-2446). Unfortunately, we did not detect any discrete absorption features from the warm absorber in the RGS, which has a much better energy resolution than EPIC.…”

An Optically Thick Disk Wind in Gro J1655–40?

“…From a detailed analysis of the absorption line profile, they detected multiple components in the wind, where a more ionized part was located at a smaller radius. After Miller et al (2006) first reported the Chandra/HETG result, the unusual wind in GRO J1655−40 has been revisited many times from both observational and theoretical points of view (Netzer 2006;Miller et al 2008;Kallman et al 2009;Luketic et al 2010;Neilsen & Homan 2012;Higginbottom & Proga 2015). Many previous studies were based on the assumption that the wind was optically thin and launched at a few percent of the Eddington luminosity, in constructing photoionized plasma models and performing hydrodynamic simulations.…”

K-shell energy levels and radiative rates for transitions in Si ix

“…While the iron K emission line exists in almost all X-ray sources , K-line features from silicon have also been commonly observed (Kaspi et al 2001(Kaspi et al , 2002Kallman et al 2009). Young et al (2005) reported the detection of H-like Si absorption lines in MCG 6-30-15 and determined the outflow velocity by measuring the line blueshift.…”

“…Based on the information (such as the column density, electron temperature, ionization states, wind velocity, and abundances) obtained by analysis of these high-resolution spectra, mechanisms that drive and heat plasmas can be deduced. Determining the abundance of various elements can shed light on the chemical evolution and origin of the hosting galaxy (Kallman et al 2009). The L-shell transition lines from low-ionization ions of Si are used to identify them in UV spectra (Ebrero et al 2013).…”