129 citations · 1.1k across the 38 of their papers we have counts for
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Cross-spectral Analysis of the Type-C Quasi-periodic Oscillation Shoulder Component in GX 339-4
Haifan Zhu, Mariano Méndez, Pengcheng Yang +8
We revisit Rossi X-ray Timing Explorer (RXTE) observations of GX~3394 during the rising phase of its 2006/2007 outburst and apply a joint power-density-spectrum (PDS)--cross-spe…
Geometry of the comptonization region of MAXI J1348630 through type-C quasi-periodic oscillations with NICER
Kevin Alabarta, Mariano Méndez, Federico García +5
We use the rms and lag spectra of the type-C quasi-periodic oscillation (QPO) to study the properties of the Comptonisation region (aka corona) during the low/hard and hard-interme…
Studies on the soft intermediate state X-ray flare of MAXI J1535-571 during its 2017 outburst
Ruican Ma, Lian Tao, Mariano Méndez +15
We analyzed an observation with the Nuclear Spectroscopic Telescope Array of the black-hole X-ray binary MAXI J1535-571 in the soft intermediate state, in which we detected a 2.5-k…
A systematic study of the high-frequency bump in the black-hole low-mass X-ray binary GX 339-4
Yuexin Zhang, Mariano Méndez, Sara E. Motta +8
The high-frequency bump, characterized by a frequency exceeding ~30 Hz, represents a seldom-explored time-variability feature in the power density spectrum (PDS) of black-hole X-ra…
Type-A quasi-periodic oscillation in the black hole transient MAXI J1348-630
Liang Zhang, Mariano Méndez, Federico García +12
We present a detailed analysis of the spectral and timing characteristics of a 7-Hz type-A quasi-periodic oscillation (QPO) detected in NICER observations of the black hole X-ray b…
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
Ruican Ma, Mariano Mendez, Federico Garcia +3
We analyze a Neutron Star Interior Composition Explorer (NICER) observation of the black hole X-ray binary MAXI J1820+070 during a transition from type-C to type-B quasi-periodic o…
The mHz quasi-regular modulations of 4U 1630--47 during its 1998 outburst
Qingchang Zhao, Hongxing Yin, Lian Tao +19
We present the results of a detailed timing and spectral analysis of the quasi-regular modulation (QRM) phenomenon in the black hole X-ray binary 4U 1630--47 during its 1998 outbur…
QPOML: A Machine Learning Approach to Detect and Characterize Quasi-Periodic Oscillations in X-ray Binaries
Thaddaeus J. Kiker, James F. Steiner, Cecilia Garraffo +2
Astronomy is presently experiencing profound growth in the deployment of machine learning to explore large datasets. However, transient quasi-periodic oscillations (QPOs) which app…
Hilbert-Huang Transform analysis of quasi-periodic oscillations in MAXI J1820+070
Wei Yu, Qing-Cui Bu, Zi-Xu Yang +14
We present time-frequency analysis, based on the Hilbert-Huang transform (HHT), of the evolution on the low-frequency quasi-periodic oscillations (LFQPOs) observed in the black hol…
A spectral-timing study of the inner flow geometry in MAXI J1535--571 with -HXMT and NICER
Wei Yu, Qing-Cui Bu, He-Xin Liu +48
We have performed a spectral-timing analysis on the black hole X-ray binary MAXI J1535--571 during its 2017 outburst, with the aim of exploring the evolution of the inner accretion…
Fast transitions of X-ray variability in the black hole transient GX 339--4: comparison with MAXI J1820+070 and MAXI J1348-630
Zi-Xu Yang, Liang Zhang, S. N. Zhang +30
Fast transitions between different types of power density spectra (PDS) happening over timescales of several tens of seconds are rare phenomena in black hole X-ray binaries. In thi…
A NICER look at the jet-like corona of MAXI J1535-571 through type-B quasi-periodic oscillations
Yuexin Zhang, Mariano Méndez, Federico García +7
MAXI J1535-571 is a black-hole X-ray binary that in 2017 exhibited a very bright outburst which reached a peak flux of up to 5 Crab in the 2-20 keV band. Given the high flux, sever…
The comptonizing medium of the black-hole X-ray binary MAXI~J1535571 through type-C quasi-periodic oscillations
Divya Rawat, Mariano Méndez, Federico García +7
We present a detailed spectral and temporal analysis of the black-hole candidate MAXI~J1535571 using NICER observations in September and October 2017. We focus specifically on o…
Distribution of gamma-ray bursts on the t90-hardness ratio plane and their classification revisited
Liang Zhang, Juan-Juan Luo, Yong-Feng Huang +2
Using four mixed bivariate distributions (Normal distribution, Skew-Normal distribution, Student distribution, Skew-Student distribution) and bootstrap re-sampling analysis, we ana…
A possible 250-second X-ray quasi-periodicity in the fast blue optical transient AT2018cow
Wenjie Zhang, Xinwen Shu, Jin-Hong Chen +11
The fast blue optical transients (FBOTs) are a new population of extragalactic transients of unclear physical origin. A variety of mechanisms have been proposed including failed su…
High energy Millihertz quasi-periodic oscillations in 1A 0535+262 with Insight-HXMT challenge current models
Ruican Ma, Lian Tao, Shuang-Nan Zhang +21
We studied the millihertz quasi-periodic oscillation (mHz QPO) in the 2020 outburst of the Be/X-ray binary 1A 0535+262 using Insight-HXMT data over a broad energy band. The mHz QPO…
An Insight-HXMT view of the mHz quasi-regular modulation phenomenon in the black hole X-ray binary 4U 1630-47
Zi-Xu Yang, Liang Zhang, Yue Huang +97
Here we report the spectral-timing results of the black hole X-ray binary 4U 1630-47 during its 2021 outburst using observations from the Hard X-ray Modulation Telescope. Type-C qu…
Determination of QPO properties in the presence of strong broad-band noise: a case study on the data of MAXI J1820+070
Deng-Ke Zhou, Shuang-Nan Zhang, Li-Ming Song +8
Accurate calculation of the phase lags of quasi-periodic oscillations (QPOs) will provide insight into their origin. In this paper we investigate the phase lag correction method wh…
Variability and phase lags of the type-C quasi-periodic oscillation of MAXI J1348-630 with NICER
Kevin Alabarta, Mariano Méndez, Federico García +4
We study the properties of the type-C quasi-periodic oscillation (type-C QPO) of MAXI J1348-630 during its 2019 outburst and reflare with NICER. This is the first time that the evo…
The evolving properties of the corona of GRS 1915+105: A spectral-timing perspective through variable-Comptonisation modelling
Federico García, Konstantinos Karpouzas, Mariano Méndez +4
The inverse Compton process by which soft photons are up-scattered by hot electrons in a corona plays a fundamental role in shaping the X-ray spectra of black-hole (BH) low-mass X-…
The evolution of the high-frequency variability in the black hole candidate GRS 1915+105 as seen by RXTE
Yuexin Zhang, Mariano Méndez, Federico García +5
GRS 1915+105 can show type-C quasi-periodic oscillations (QPOs) in the power density spectrum. A high-frequency QPO (HFQPO) at 67 Hz has been observed in this source, albeit less o…
The accretion flow geometry of MAXI J1820+070 through broadband noise research with Insight-HXMT
Zi-Xu Yang, Liang Zhang, Qing-Cui Bu +24
Here we present a detailed study of the broadband noise in the power density spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of its 2018 outburst, using…
The evolution of the corona in MAXI J1535-571 through type-C quasi-periodic oscillations with Insight-HXMT
Yuexin Zhang, Mariano Méndez, Federico García +14
Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients can appear when the source is in the low-hard and hard-intermediate states. The spectral-timing evolution o…
Coupling between the accreting corona and the relativistic jet in the micro quasar GRS 1915+105
Mariano Mendez, Konstantinos Karpouzas, Federico Garcia +4
GRS 1915+105 was the first stellar-mass black-hole in our Galaxy to display a superluminal radio jet, similar to those observed in active galactic nuclei with a supermassive black…