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On the X-ray origin in Quiescent Black Hole X-ray Binaries. Hui Zhang ( 张惠 ) Shanghai Astronomical Observatory, Chinese Academy of Sciences. Collaborators: Feng Yuan (SHAO) Wei Cui (Purdue University)
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On the X-ray origin in Quiescent Black Hole X-ray Binaries Hui Zhang (张惠) Shanghai Astronomical Observatory, Chinese Academy of Sciences Collaborators: Feng Yuan (SHAO) Wei Cui (Purdue University) Gabor Pszota (Purdue University)
Outline • Introduction: • (a)observation of Black hole X-ray binary • (b) theoretical model: Coupled accretion-Jet • 2. Prediction of Yuan & Cui for quiescent state • 3.X-ray Observation results of three • sources in quiescent state • 4.Our modeling results
What is black hole X-ray binary? • More than 40 black hole X-ray binaries and their candidates have been found in our Galaxy. • They are in the quiescent state in most of their life. • When the accretion rate increases, some instability mechanism happen, then outburst occurs, going through various states
Models for various Spectral states Esin et al. 1997, ApJ
Spectral states in black hole binaries • Quiescent State: -Large transient radius; -very low luminosity, Lx~1030.5-1033.5 erg/s ; -power law spectrumphoton index =1.5~2.1; -Jet is thought to be exist • Hard State: • - power law spectrum >80% (2-20keV) • - power law spectrumphoton index =1.4~2.1 • - strong varibility (QPO) • - strong radio emission (Jet exist) • SPL/Very High State/Intermediate State : • -power law spectrum photon index >2.4 • - power law component>20% (2-20keV)and QPO • -power law component>50% (2-20keV) and no QPO • -radio flare at HSVHS • High Soft State (Thermal Dominant State): -disk component>75%(2-20keV) -no QPO or QPO is toot weak to be detected -very weak radio emission and no Jet exist -power law spectrum photon index =2.1~4.8 Done, C. 2007, A&ARv
Jet:Radio, infrared SSD:Opt/UV ADAF:X-ray, Opt/UV Coupled Accretion-Jet Models
Coupled Accretion-Jet Models • Standard thin disk (SSD): -geometrical thin, optical thick - T r-3/4 -multicolor black body spectrum • Advection Dominated Accretion Flow (ADAF): -geometrical thick, optical thin -Compton scattering, synchrotron, bremsstrahlung -strong advection, low emission efficiency -double high temperature plasma • Jet model: -internal shock -power law distribution of electron -synchrotron emission dominated
ADAF-Jet Models for hard state Success in hard state of XTE J1118+480! Jet SSD ADAF Yuan, Cui & Narayan, 2005, ApJ
LR~LX0.7 Radio/X-ray correlation Gallo et al. 2003, MNRAS, 344
1. When the accretion rate decreases, the correlation between • the radio and X-ray still exist, but when the luminosity lower • than a certain critical value, the correlation will change and • become more steeper than before. • Because Lacc,x M2, LJet,x M . • So most of the X-ray comes from Jet in quiescent state. • Because jet radiation dominates below this critical luminosity, • the spectrum of X-ray is a power law. Yuan & Cui 2005 prediction
The critical luminosity : Lcrit~(10-5~10-6)LEdd Yuan & Cui 2005,ApJ The change of the radio—X-ray correlation from hard to quiescent states
Recent new study result: Yuan & Cui 2005 also predicted: Recently, Wrobel, Terashima & Ho 2008 studied two quiesent LLAGN in NGC 4621 and NGC 4697, they found the observed radio luminosity is within a factor of 3 of the predicted value (based on Lx~10-9 LEdd and the relation above).
XMM/Newton Observation of Quiescent Sources We observed two black hole X-ray binaries XTE J1550-564 and GRO J1655-40 for long time by XMM-Newton. We also analysed V404 Cyg from archival data.
ADAF ADAF SSD Jet Modeling results (GRO J1655-40)
ADAF ADAF Jet SSD Modeling results (V404Cyg)
ADAF ADAF Jet SSD Modeling results (XTE J1550-564)
Conclusion Jet model can fit all the X-ray spectrum of these three sources, but for XTE J1550-564, It can also be modeled by ADAF . Because the spectrum of ADAF is curved at low accretion rate, however, the spectrum of Jet is power-law. In quiescent black hole X-ray binaries, the X-ray emission originates from Jet !