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Evidence for Disk Truncation at Low Accretion States of the Black Hole Binary MAXI J1820+070 Observed by NuSTAR and XMM-Newton
- Publication Year :
- 2020
- Publisher :
- arXiv, 2020.
-
Abstract
- We present results from NuSTAR and XMM-Newton observations of the new black hole X-ray binary MAXI J1820+070 at low accretion rates (below 1% of the Eddington luminosity). We detect a narrow Fe K$\alpha$ emission line, in contrast to the broad and asymmetric Fe K$\alpha$ line profiles commonly present in black hole binaries at high accretion rates. The narrow line, with weak relativistic broadening, indicates that the Fe K$\alpha$ line is produced at a large disk radius. Fitting with disk reflection models assuming standard disk emissivity finds a large disk truncation radius (a few tens to a few hundreds of gravitational radii, depending on the disk inclination). In addition, we detect a quasi-periodic oscillation (QPO) varying in frequency between $11.6\pm0.2$~mHz and $2.8\pm0.1$~mHz. The very low QPO frequencies suggest a large size for the optically-thin Comptonization region according to the Lense-Thirring precession model, supporting that the accretion disk recedes from the ISCO and is replaced by advection-dominated accretion flow at low accretion rates. We also discuss the possibility of an alternative accretion geometry that the narrow Fe K$\alpha$ line is produced by a lamppost corona with a large height illuminating the disk.<br />Comment: 8 pages, 5 figures, accepted for publication in ApJ
- Subjects :
- 010504 meteorology & atmospheric sciences
Astrophysics::High Energy Astrophysical Phenomena
Binary number
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
Gravitation
symbols.namesake
0103 physical sciences
Emissivity
Emission spectrum
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Physics
High Energy Astrophysical Phenomena (astro-ph.HE)
Astronomy and Astrophysics
Radius
Accretion (astrophysics)
Black hole
Space and Planetary Science
Eddington luminosity
symbols
Astrophysics::Earth and Planetary Astrophysics
Astrophysics - High Energy Astrophysical Phenomena
Subjects
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....9ace39e992c04912d8b5944071855f5f
- Full Text :
- https://doi.org/10.48550/arxiv.2003.01778