scholarly journals Accretion disc–jet couplings in X-ray binaries

2020 ◽  
Vol 495 (2) ◽  
pp. 2408-2415
Author(s):  
Pei-Xin Shen ◽  
Wei-Min Gu
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Flow Model ◽  
Accretion Disc ◽  
X Ray ◽  
Accretion Flow ◽  
Disc Model ◽  
Hard State ◽  
X Ray Binaries ◽  
Jet Power

ABSTRACT When the matter from a companion star is accreted towards the central compact accretor, i.e. a black hole (BH) or a neutron star (NS), an accretion disc and a jet outflow will form, providing bight X-ray and radio emission, which is known as X-ray binaries (XRBs). In the low/hard state, there exist disc–jet couplings in XRBs, but it remains uncertain whether the jet power comes from the disc or the central accretor. Moreover, black hole X-ray binaries (BHXRBs) have different properties compared with neutron star X-ray binaries (NSXRBs): quiescent BHXRBs are typically two to three orders of magnitude less luminous than NSXRBs in X-ray, whereas BHXRBs are more radio loud than NSXRBs. In observations, an empirical correlation has been established between radio and X-ray luminosity, $L_{\rm R} \propto L_{\rm X}^b$, where b ∼ 0.7 for BHXRBs and b ∼ 1.4 for non-pulsating NSXRBs. However, there are some outliers of BHXRBs showing unusually steep correlation as NSXRBs at higher luminosities. In this work, under the assumption that the origin of jet power is related to the internal energy of the inner disc, we apply our magnetized, radiatively efficient thin disc model and the well-known radiatively inefficient accretion flow model to NSXRBs and BHXRBs. We find that the observed radio/X-ray correlations in XRBs can be well understood by the disc–jet couplings.

scholarly journals Hard state neutron star and black hole X-ray binaries in the radio:X-ray luminosity plane

2018 ◽  
Vol 478 (1) ◽  
pp. L132-L136 ◽  
Author(s):  
Elena Gallo ◽  
Nathalie Degenaar ◽  
Jakob van den Eijnden
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
X Ray ◽  
Hard State ◽  
X Ray Binaries

scholarly journals Isolating the jet in broadband spectra of XBs

2010 ◽  
Vol 6 (S275) ◽  
pp. 317-318
Author(s):  
David M. Russell ◽  
Fraser Lewis ◽  
Dipankar Maitra ◽  
Robert J. H. Dunn ◽  
Sera Markoff ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Law ◽  
Spectral Energy ◽  
Synchrotron Emission ◽  
Energy Distributions ◽  
X Ray ◽  
Relativistic Jet ◽  
Hard State ◽  
X Ray Binaries

AbstractMost accretion-powered relativistic jet sources in our Galaxy are transient X-ray binaries (XBs). Efforts to coordinate multiwavelength observations of these objects have improved dramatically over the last decade. Now the challenge is to interpret broadband spectral energy distributions (SEDs) of XBs that are well sampled in both wavelength and time. Here we focus on the evolution of the jet in their broadband spectra. Some of the most densely sampled broadband SEDs of a neutron star transient (IGR J00291+5934) are used to constrain the optically thick–thin break in the jet spectrum. For the black hole transient XTE J1550-564, infrared – X-ray correlations, evolution of broadband spectra and timing signatures indicate that synchrotron emission from the jet likely dominates the X-ray power law at low luminosities (~(2 × 10−4 − 2 × 10−3) LEdd) during the hard state outburst decline.

The wind production from black hole hot accretion flow

2018 ◽  
Vol 14 (S342) ◽  
pp. 214-217
Author(s):  
De-Fu Bu
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Gravity Potential ◽  
Centrifugal Forces ◽  
X Ray ◽  
Accretion Flow ◽  
Mhd Simulations ◽  
Hard State ◽  
X Ray Binaries

AbstractObservations of low luminosity active galactic nuclei (LLAGNs) and the hard state of black hole X-ray binaries (BHBs) show that the wind exists. Black hole in LLAGNs and hard state of BHBs accretes gas in hot accretion mode. In this paper, we first use magnetohydrodynamic (MHD) simulations of hot accretion flow around a black hole to study the origin of the wind. We find that the wind is driven by the combination of gradients of gas and magnetic pressure and centrifugal forces. Second, we use simulations with focus on the region around Bondi radius to study whether the wind can be generated outside Bondi radius. In the simulation studying hot accretion flow around Bondi radius, in addition to the black hole gravity, we also take into account the gravity of nuclei stars. We find that the wind can not be generated outside Bondi radius. The absence of the wind is due to the change of gravity potential.

scholarly journals Disk–jet coupling changes as a possible indicator for outbursts from GX 339−4 remaining within the X-ray hard state

2020 ◽  
Author(s):  
S E M de Haas ◽  
T D Russell ◽  
N Degenaar ◽  
S Markoff ◽  
A J Tetarenko ◽  
...  
Keyword(s):  
Black Hole ◽  
X Ray ◽  
Accretion Flow ◽  
Galactic Black Hole ◽  
Hard State ◽  
Order Of Magnitude ◽  
X Ray Binaries ◽  
Best Fit ◽  
Spectral State

Abstract We present quasi-simultaneous radio, (sub-)millimetre, and X-ray observations of the Galactic black hole X-ray binary, taken during its 2017–2018 outburst, where the source remained in the hard X-ray spectral state. During this outburst, GX 339−4 showed no atypical X-ray behaviour that may act as a indicator for an outburst remaining within the hard state. However, quasi-simultaneous radio and X-ray observations showed a flatter than expected coupling between the radio and X-ray luminosities (with a best fit relation of $L_{\rm radio} \propto L_{\rm X}^{0.39 \pm 0.06}$), when compared to successful outbursts from this system ($L_{\rm radio} \propto L_{\rm X}^{0.62 \pm 0.02}$). While our 2017–2018 outburst data only span a limited radio and X-ray luminosity range (∼1 order of magnitude in both, where more than 2-orders of magnitude in LX is desired), including data from other hard-only outbursts from GX 339−4 extends the luminosity range to ∼1.2 and ∼2.8 orders of magnitude, respectively, and also results in a flatter correlation (where $L_{\rm radio} \propto L_{\rm X}^{0.46 \pm 0.04}$). This result is suggestive that for GX 339−4 a flatter radio – X-ray correlation, implying a more inefficient coupling between the jet and accretion flow, could act as an indicator for a hard-only outburst. However, further monitoring of both successful and hard-only outbursts over larger luminosity ranges with strictly simultaneous radio and X-ray observations is required from different, single sources, to explore if this applies generally to the population of black hole X-ray binaries, or even GX 339−4 at higher hard-state luminosities.

scholarly journals A minimal timescale for the continuum in 4U 1608-52 and Aql X-1

2021 ◽  
Vol 502 (1) ◽  
pp. L72-L78
Author(s):  
K Mohamed ◽  
E Sonbas ◽  
K S Dhuga ◽  
E Göğüş ◽  
A Tuncer ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Spectra ◽  
Light Curves ◽  
State Transitions ◽  
Strong Positive Correlation ◽  
Present Evidence ◽  
X Ray ◽  
X Ray Binaries ◽  
The Continuum

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.

scholarly journals A Machine Learning Approach For Classifying Low-mass X-ray Binaries Based On Their Compact Object Nature

2020 ◽  
Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  
Keyword(s):  
Machine Learning ◽  
Black Hole ◽  
Neutron Star ◽  
Binary Systems ◽  
Compact Object ◽  
X Ray ◽  
Average Accuracy ◽  
Machine Learning Approach ◽  
Low Mass ◽  
X Ray Binaries

Abstract Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25 keV obtained from the Rossi X-ray Timing Explorer archive. We report an average accuracy of 87±13% in classifying the spectra of LMXB sources. We further use the trained model for predicting the classes for LMXB systems with unknown or ambiguous classification. With the ever-increasing volume of astronomical data in the X-ray domain from present and upcoming missions (e.g., SWIFT, XMM-Newton, XARM, ATHENA, NICER), such methods can be extremely useful for faster and robust classification of X-ray sources and can also be deployed as part of the data reduction pipeline.

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