TY - JOUR
T1 - A variable corona during the transition from type-C to type-B quasi-periodic oscillations in the black hole X-ray binary MAXI J1820+070
AU - Ma, Ruican
AU - Méndez, Mariano
AU - García, Federico
AU - Sai, Na
AU - Zhang, Liang
AU - Zhang, Yuexin
N1 - Funding Information:
We thank the anonymous referee for useful comments that helped us improve the paper. We thank Kevin Alabarta for providing a script that helped process the NICER data. We thank Thomas Russell and Dave Russell for useful comments. This work is supported by the China Scholarship Council (CSC 202104910402). MM acknowledges the research programme Athena with project number 184.034.002, which is (partly) financed by the Dutch Research Council (NWO). FG is a CONICET researcher. FG acknowledges support by PIP 0113 (CONICET), PICT-2017-2865 (ANPCyT), and PIBAA 1275 (CONICET). YZ acknowledges support from China Scholarship Council (CSC 201906100030). MM and FG thank the Team Meeting at the International Space Science Institute (Bern) for fruitful discussions. This research has made use of NASA’s Astrophysics Data System.
Publisher Copyright:
© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - We analyse a Neutron Star Interior Composition Explorer observation of the black hole X-ray binary MAXI J1820+070 during a transition from type-C to type-B quasi-periodic oscillations (QPOs). We find that below ∼2 keV, for the type-B QPOs the rms amplitude is lower and the magnitude of the phase lags is larger than for the type-C QPOs. Above that energy, the rms and phase-lag spectra of the type-B and type-C QPOs are consistent with being the same. We perform a joint fit of the time-averaged spectra of the source, and the rms and phase-lag spectra of the QPOs with the time-dependent Comptonization model vkompth to study the geometry of the corona during the transition. We find that the data can be well fitted with a model consisting of a small and a large corona that are physically connected. The sizes of the small and large coronae increase gradually during the type-C QPO phase whereas they decrease abruptly at the transition to type-B QPO. At the same time, the inner radius of the disc moves inward at the QPO transition. Combined with simultaneous radio observations showing that discrete jet ejections happen around the time of the QPO transition, we propose that a corona that expands horizontally during the type-C QPO phase, from ∼104 km () to 105 km () overlying the accretion disc, transforms into a vertical jet-like corona extending over ∼104 km () during the type-B QPO phase.
AB - We analyse a Neutron Star Interior Composition Explorer observation of the black hole X-ray binary MAXI J1820+070 during a transition from type-C to type-B quasi-periodic oscillations (QPOs). We find that below ∼2 keV, for the type-B QPOs the rms amplitude is lower and the magnitude of the phase lags is larger than for the type-C QPOs. Above that energy, the rms and phase-lag spectra of the type-B and type-C QPOs are consistent with being the same. We perform a joint fit of the time-averaged spectra of the source, and the rms and phase-lag spectra of the QPOs with the time-dependent Comptonization model vkompth to study the geometry of the corona during the transition. We find that the data can be well fitted with a model consisting of a small and a large corona that are physically connected. The sizes of the small and large coronae increase gradually during the type-C QPO phase whereas they decrease abruptly at the transition to type-B QPO. At the same time, the inner radius of the disc moves inward at the QPO transition. Combined with simultaneous radio observations showing that discrete jet ejections happen around the time of the QPO transition, we propose that a corona that expands horizontally during the type-C QPO phase, from ∼104 km () to 105 km () overlying the accretion disc, transforms into a vertical jet-like corona extending over ∼104 km () during the type-B QPO phase.
KW - accretion, accretion discs
KW - stars: black holes
KW - stars: individual: MAXI J1820+070
KW - X-rays: binaries
UR - http://www.scopus.com/inward/record.url?scp=85169880510&partnerID=8YFLogxK
U2 - 10.1093/mnras/stad2284
DO - 10.1093/mnras/stad2284
M3 - Article
AN - SCOPUS:85169880510
SN - 0035-8711
VL - 525
SP - 854
EP - 875
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -