205 citations · 438 across the 19 of their papers we have counts for
16 papers · 1 filter
Resolving a Clumpy Disk Wind in 4U 1957+115 with XRISM
Paul A. Draghis, Erin Kara, Ehud Behar +7
We present a high-resolution XRISM/Resolve observation of the persistent black hole candidate 4U 1957+115, revealing the first detection of an intrinsic disk wind in this source. T…
Quasi-periodic eruption spectral-timing: EMRIs crossing warped accretion disks
Joheen Chakraborty, Andrew Mummery, Eliot Quataert +3
Quasi-periodic eruptions (QPEs) are repeating X-ray transients from galactic nuclei potentially caused by a stellar-mass orbiter repeatedly colliding with the accretion disk of a s…
Relativistic outflows power a quasi-periodic eruption: constraints on energetics, mass loss, and emission mechanisms
Joheen Chakraborty, Erin Kara, Wenbin Lu +17
Quasi-periodic eruptions (QPEs) are recurring bursts of X-ray radiation originating from supermassive black holes (SMBHs). They are an unprecedented type of structured, high-amplit…
Observations of X-ray quasi-periodic eruptions
Thomas Wevers, Joheen Chakraborty, Erwan Quintin +2
Quasi-periodic eruptions (QPEs) are a novel class of repeating nuclear transients, discovered exclusively in the X-ray band to date. Since their initial discovery in 2019, the QPE…
Rapid Orbital Decay in the Ultracompact Double-degenerate Binary eRASSU J060839.5704014
Rahul Sharma, Chandreyee Maitra, Frank Haberl +9
We present timing and spectral analysis of the recently identified ultracompact double-degenerate (DD) white dwarf binary eRASSU J060839.5704014 using observations from NICER an…
A positive period derivative in the quasi-periodic eruptions of ZTF19acnskyy
Joheen Chakraborty, Saul A. Rappaport, Riccardo Arcodia +9
We report the first direct measurement of the period derivative in a quasi-periodic eruption (QPE), finding a smoothly increasing period with $\dot{P}\approx (1.7\pm 0.02)\times10^…
X-ray Spectral-Timing Properties of Tidal Disruption Events
Joheen Chakraborty, Megan Masterson, Andrew Mummery +4
We perform the first systematic study of the minute-to-hours-timescale stochastic variability observed in the X-ray luminosity of tidal disruption events (TDEs) using XMM-Newton da…
Disk-to-Corona State Transition and Extreme X-ray Variability in the Tidal Disruption Event AT2019teq
Vera Berger, Erin Kara, Joheen Chakraborty +2
We present a five-year X-ray spectral and timing analysis of the optically selected Tidal Disruption Event (TDE) AT2019teq, which displays extreme variability, including order-of-m…
XRISM finds the Changing-Look AGN NGC 1365 in an extended low state: A dense, highly ionized outflow obscures the central source
Fatima Zaidouni, Erin Kara, Peter Kosec +21
We present the first XRISM/Resolve observations of the active galactic nucleus, NGC 1365, obtained in 2024 February and July. NGC 1365 is known for rapid transitions between Compto…
The Advanced X-ray Imaging Satellite (AXIS) Community Science Book
Michael Koss, Nafisa Aftab, Steven W. Allen +395
The AXIS Community Science Book represents the collective effort of 592 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (A…
Prospects for EMRI/MBH parameter estimation using Quasi-Periodic Eruption timings: short-timescale analysis
Joheen Chakraborty, Lisa V. Drummond, Matteo Bonetti +11
Quasi-Periodic Eruptions (QPEs) are luminous, recurring X-ray outbursts from galactic nuclei, with timescales of hours to days. While their origin remains uncertain, leading models…
Millihertz Oscillations Near the Innermost Orbit of a Supermassive Black Hole
Megan Masterson, Erin Kara, Christos Panagiotou +22
Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repet…
Eppur si muove: Evidence of disc precession or a sub-milliparsec SMBH binary in the QPE-emitting galaxy GSN 069
Giovanni Miniutti, Alessia Franchini, Matteo Bonetti +8
X-ray quasi-periodic eruptions (QPEs) are intense soft X-ray bursts from the nuclei of nearby low-mass galaxies typically lasting about one hour and repeating every few. Their phys…
Expanding the ultracompacts: gravitational wave-driven mass transfer in the shortest-period binaries with accretion disks
Joheen Chakraborty, Kevin B. Burdge, Saul A. Rappaport +35
We report the discovery of three ultracompact binary white dwarf systems hosting accretion disks, with orbital periods of 7.95, 8.68, and 13.15 minutes. This significantly augments…
Alive and kicking: A new QPE phase in GSN 069 revealing a quiescent luminosity threshold for QPEs
G. Miniutti, M. Giustini, R. Arcodia +4
X-ray quasi-periodic eruptions (QPEs) are intense repeating soft X-ray bursts from the nuclei of nearby galaxies. Their physical origin is still largely unconstrained, and several…
Possible X-ray Quasi-Periodic Eruptions in a Tidal Disruption Event Candidate
Joheen Chakraborty, Erin Kara, Megan Masterson +3
X-ray Quasi-Periodic Eruptions (QPEs) are a recently discovered phenomenon associated with supermassive black holes at the centers of galaxies. They are high amplitude soft X-ray f…