Query : 2021A&A...647A.173K

2021A&A...647A.173K - Astronomy and Astrophysics, volume 647A, 173-173 (2021/3-1)

ALMA/NICER observations of GRS 1915+105 indicate a return to a hard state.


Abstract (from CDS):

Context.GRS 1915+105 is a transient black hole X-ray binary consistently emitting 10-100% of the Eddington luminosity in the X-ray band over the last three decades until mid-2018 when the source luminosity suddenly decreased by an order of magnitude. This phase was followed by a change to a state with even lower average X-ray fluxes never seen before during the outburst but presenting renewed flaring activity at different wavelengths, albeit with mean fluxes still in decline.
Aims.GRS 1915+105 has the longest orbital period known among low-mass X-ray binaries, the largest accretion disk size, and therefore the largest mass supply for accretion. The high inclination of the disk allows the study of geometrical effects of the accretion flow such as changes in the height-to-radius ratio or the effect of accretion disk winds on the intrinsic emission that is expected during the outburst decay. In addition, the transient jet is expected to change to a compact, self-absorbed, steady jet.
Methods. We conducted two full polarization Atacama Large Millimeter Array observations to study the jet properties during the outburst decay by analyzing the spectral, polarization, and intra-epoch variability for both observation epochs. In addition, we analyzed almost daily Neutron Star Interior Composition Explorer pointing observations, modeling X-ray power spectral densities, spectral energy distributions, and light curves with a physically motivated model to follow the changing accretion disk properties throughout the outburst decay and relating them to the jet emission.
Results. We show that the X-ray and millimeter (mm) spectral, timing, and polarization properties are consistent with those of a typical decaying X-ray binary outburst and that GRS 1915+105 has descended into the low-luminosity hard X-ray state. The jet emission in the mm is consistent with a compact, steady jet with ∼1% linear polarization, and the magnetic field is likely aligned with the jet position angle. Relating the mm emission to the X-ray emission reveals that the source has changed from a higher radio/X-ray correlation index to a lower one; Lradio ∝ LX0.6.

Abstract Copyright: © ESO 2021

Journal keyword(s): accretion - accretion disks - binaries : close - stars: black holes - stars: winds - outflows - X-rays: binaries - stars: individual: GRS 1915+105

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* V821 Ara HXB 17 02 49.3876391280 -48 47 23.087954544 16.20 16.30 15.5     ~ 1981 0
2 NVSS J190539+095208 Rad 19 05 39.89897022 +09 52 08.4074677           ~ 18 1
3 Granat 1915+105 HXB 19 15 11.55576 +10 56 44.9052           ~ 2503 0
4 GB6 B1920+1524 Rad 19 22 34.69936025 +15 30 10.0326112           ~ 56 0
5 QSO B1921-293 BLL 19 24 51.05595254 -29 14 30.1210248   18.71 18.21 15.07   ~ 808 0

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