Do X-ray binary spectral state transition luminosities vary?

Abstract Soft Ultra-Luminous X-ray (ULXs) sources are a sub-class of the ULXs that can switch from a supersoft spectral state, where most of the luminosity is emitted below 1 keV, to a soft spectral state with significant emission above 1 keV. In a few systems, dips have been observed. The mechanism behind this state transition and the dips nature are still debated. To investigate these issues, we obtained a long XMM-Newton monitoring campaign of a member of this class, NGC 247 ULX-1. We computed the hardness-intensity diagram for the whole data-set and identified two different branches: the normal branch and the dipping branch, which we study with four and three hardness-intensity resolved spectra, respectively. All seven spectra are well described by two thermal components: a colder (kTbb ∼ 0.1-0.2 keV) black-body, interpreted as emission from the photo-sphere of a radiatively-driven wind, and a hotter (kTdisk ∼ 0.6 keV) multi-colour disk black-body, likely due to reprocessing of radiation emitted from the innermost regions. In addition, a complex pattern of emission and absorption lines has been taken into account based on previous high-resolution spectroscopic results. We studied the evolution of spectral parameters and flux of the two thermal components along the two branches and discuss two scenarios possibly connecting the state transition and the dipping phenomenon. One is based on geometrical occultation of the emitting regions, the other invokes the onset of a propeller effect.

Download Full-text

A Study on the Hysteresis Effect and Spectral Evolution in the Mini-Outbursts of Black Hole X-Ray Binary XTE J1550-564

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.651661 ◽

2021 ◽

Vol 8 ◽

Author(s):

Ai-Jun Dong ◽

Chang Liu ◽

Kang Ge ◽

Xiang Liu ◽

Qi-Jun Zhi ◽

...

Keyword(s):

Black Hole ◽

State Transition ◽

Hysteresis Effect ◽

Transition Model ◽

Spectral Evolution ◽

X Ray ◽

Photon Count ◽

Hard State ◽

State Transition Model ◽

Spectral State

One normal outburst and three mini-outbursts have been detected by Rossi X-ray Timing Explorer satellite after 2000 in the well-known black hole X-ray binary XTE J1550-564. In this work, we explore the hysteresis effect of the four outbursts, which is a phenomenon that a similar spectral state transition occurs at different luminosity in an outburst of black hole X-ray binary. A q-like track was found in the hardness-intensity diagram of the normal outburst in 2000 but not in the three mini-outbursts that only occur in the Low/Hard state. The results demonstrate that the hysteresis effect is not apparent in the three mini-outbursts and the X-ray spectra are harder than that of the normal outburst at the same photon count rate. Furthermore, the results of the correlation analysis show that the Γ − F2−10keV correlation of mini-outburst maintain negative in the Low/Hard state with the harder spectra than that of the normal outburst at the same X-ray flux. The X-ray spectral evolution can be well-explained by the state-transition model from the Shakura–Sunyaev disk to the advection-dominated accretion flow, which implies that the three mini-outbursts of XTE J1550-564 might originate from a smaller discrete accretion event.

Download Full-text

XMM-Newton observation of a spectral state transition in the peculiar radio/X-ray/γ-ray source LS I +61 303

Astronomy and Astrophysics ◽

10.1051/0004-6361:20065933 ◽

2006 ◽

Vol 459 (3) ◽

pp. 901-907 ◽

Cited By ~ 49

Author(s):

L. Sidoli ◽

A. Pellizzoni ◽

S. Vercellone ◽

M. Moroni ◽

S. Mereghetti ◽

...

Keyword(s):

State Transition ◽

X Ray ◽

Γ Ray ◽

Spectral State

Download Full-text

Propeller‐driven Spectral State Transition in the Low‐Mass X‐Ray Binary 4U 1608−52

The Astrophysical Journal ◽

10.1086/506338 ◽

2006 ◽

Vol 650 (1) ◽

pp. 299-302 ◽

Cited By ~ 11

Author(s):

Xie Chen ◽

Shuang Nan Zhang ◽

Guo Qiang Ding

Keyword(s):

State Transition ◽

X Ray ◽

Low Mass ◽

Spectral State

Download Full-text

An H i absorption distance to the black hole candidate X-ray binary MAXI J1535–571

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz113 ◽

2019 ◽

Vol 488 (1) ◽

pp. L129-L133 ◽

Cited By ~ 6

Author(s):

J Chauhan ◽

J C A Miller-Jones ◽

G E Anderson ◽

W Raja ◽

A Bahramian ◽

...

Keyword(s):

Black Hole ◽

State Transition ◽

Line Of Sight ◽

Wide Field ◽

Radio Telescopes ◽

Tangent Point ◽

Extragalactic Source ◽

X Ray ◽

Black Hole Candidate ◽

Spectral State

ABSTRACT With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored the black hole candidate X-ray binary MAXI J1535–571 over seven epochs from 2017 September 21 to October 2. Using ASKAP observations, we studied the H i absorption spectrum from gas clouds along the line of sight and thereby constrained the distance to the source. The maximum negative radial velocities measured from the H i absorption spectra for MAXI J1535–571 and an extragalactic source in the same field of view are −69 ± 4 and −89 ± 4 km s−1, respectively. This rules out the far kinematic distance ($9.3^{+0.5}_{-0.6}$ kpc), giving a most likely distance of $4.1^{+0.6}_{-0.5}$ kpc, with a strong upper limit of the tangent point at $6.7^{+0.1}_{-0.2}$ kpc. At our preferred distance, the peak unabsorbed luminosity of MAXI J1535–571 was >78 per cent of the Eddington luminosity, and shows that the soft-to-hard spectral state transition occurred at the very low luminosity of (1.2–3.4) × 10−5 times the Eddington luminosity. Finally, this study highlights the capabilities of new wide-field radio telescopes to probe Galactic transient outbursts, by allowing us to observe both a target source and a background comparison source in a single telescope pointing.

Download Full-text

Properties of Faint X-ray Activity of XTE J1908+094 in 2019

Galaxies ◽

10.3390/galaxies9020025 ◽

2021 ◽

Vol 9 (2) ◽

pp. 25

Author(s):

Debjit Chatterjee ◽

Arghajit Jana ◽

Kaushik Chatterjee ◽

Riya Bhowmick ◽

Sujoy Kumar Nath ◽

...

Keyword(s):

Black Hole ◽

Temporal Analysis ◽

Power Density Spectrum ◽

Periodic Oscillations ◽

Telescope Array ◽

Density Spectrum ◽

X Ray ◽

Black Hole Candidate ◽

Short Period ◽

Spectral State

We study the properties of the faint X-ray activity of Galactic transient black hole candidate XTE J1908+094 during its 2019 outburst. Here, we report the results of detailed spectral and temporal analysis during this outburst using observations from Nuclear Spectroscopic Telescope Array (NuSTAR). We have not observed any quasi-periodic-oscillations (QPOs) in the power density spectrum (PDS). The spectral study suggests that the source remained in the softer (more precisely, in the soft–intermediate) spectral state during this short period of X-ray activity. We notice a faint but broad Fe Kα emission line at around 6.5 keV. We also estimate the probable mass of the black hole to be 6.5−0.7+0.5M⊙, with 90% confidence.

Download Full-text