Binary X-ray with black hole GRS 1915 + 105 has a variable wind magnetic disk, the study suggests

Light curve GRS 1915 + 105 in soft condition, bucket size of 100 s. Credit: Ratheesh et al., 2020

Using NASA’s Chandra spacecraft, astronomers made high-resolution X-ray observations of the transient binary X-ray system of a black hole known as GRS 1915 + 105. They report that the source shows the changing wind of a magnetic accretion disk. The study is described in detail in a paper published Dec. 16 in the pre-print archival repository.

Binary data with black hole X-rays (BHXB) are binary systems consisting of a black hole orbiting a stellar companion, usually an evolved low-mass star. In BHXBs, X-rays are created by material that accrets from the secondary companion star into the primary black hole. Such systems are usually detected in outbursts when the X-ray flow is significantly increased.

Because of their high variability and high X-ray flux, BHXBs are excellent targets for studying the relationship between accumulation and ejection mechanisms. In the case of GRS 1915 + 105, astronomers perceive it as an interesting source that can be used to study the accretion disk and how it depends on changes in the state of binary black holes.

Now a team of astronomers led by Ajay Ratheesh from the University of Tor Vergata in Rome, Italy, performed high-resolution GRS 1915 + 105 X-ray spectroscopy with a Chandra High Energy Transmission Spectrometer (HETGS). The main objective of the study was to investigate the origin and wind geometry of the accretion disk in this BHXB.

“In this paper, we investigate the origin of the observed abrupt differences in the properties of the soft and hard wind absorption lines GRS 1915 + 105 observed in Chandra HETGS,” the researchers wrote in the paper.

The team found a series of lines for wind absorption in the soft state of GRS 1915 + 105. These lines appear to follow a nonlinear dependence of velocity width, velocity displacement, and equivalent latitude with respect to ionization. This, according to the study, indicates multiple component or layered casting. As for the solid state of the object, astronomers have found only a weak absorption line of Fe XXVI.

In general, the researchers say the results indicate a steady presence of winds from the disks even during the hard state, although their spectroscopic appearance appears to be much weaker. Moreover, the natural state of the wind appears to change internally in different states of GRS 1915 + 105. Therefore, the results suggest that the disk wind in this binary system has a magnetic origin.

“We note that the wide range of ionization seen in absorption lines, which many authors have interpreted as multiple casting (Miller et al. 2015, 2016), supports magnetic origin,” the astronomers concluded.

The authors added that the wind mass flow in GRS 1915 + 105 is comparable to the accumulation rate. This finding suggests an intimate link between the accumulation and ejection processes that lead to state changes in black hole binaries.


Continuous infrared winds detected during the eruption of a black hole of stellar mass


More information:
Variable magnetic disk wind in binary X-ray black hole GRS 1915 + 105?, ArXiv: 2012.09023 [astro-ph.HE] arxiv.org/abs/2012.09023

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Citation: X-ray binary GRS 1915 + 105 with black hole has variable wind magnetic disk, suggests study (2020, December 23) downloaded December 23, 2020 from https://phys.org/news/2020-12-black-hole -x -ray-binary-grs.html

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