129 citations · 1.7k across the 78 of their papers we have counts for
79 papers
Low-angular-momentum accretion shocks can power weak-to-moderate X-ray flares from SgrA*
Samik Mitra, Bożena Czerny, Michal Zajaček +1
X-ray flares from Sgr~A* span broad ranges in duration, fluence, and luminosity, but their origin remains unsettled. We test whether standing shocks in low-angular-momentum magneti…
What is the reason for the lack of cool evolved stars near the center of the Galaxy?
Petr Kurfürst, Michal Zajaček, Norbert Werner +2
The observed deficit of bright late-type giants in the central parsec of the Milky Way remains an open problem. We investigate whether repeated passages of red giants (RGs) through…
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…
The Nearest Galactic Nucleus: Studying the Galactic Centre with SKA-Mid
Rainer Schoedel, Antxon Alberdi, Izaskun Jiménez-Serra +24
The Galactic Centre is the nearest nucleus of a galaxy and the most extreme environment that we can observe down to physical scales of a few hundred astronomical units. There is no…
Tidal disruption of a low-mass star in an active galactic nucleus as the origin of the PS16dtm outburst
Marzena Śniegowska, Bożena Czerny, Michal Zajaček +7
The event PS16dtm, which occured in the center of the Narrow Line Seyfert 1 (NLS1) galaxy SDSS J015804.75-005221.8 (z = 0.080440), is one of the few candidates for a tidal disrupti…
Eclipses of Nearby Millimeter-bright Galactic Nuclei by Stars in Nuclear Star Clusters
Michal Zajaček
It is of a general interest to look for signatures of stellar bodies orbiting supermassive black holes (SMBHs) in galactic nuclei other than the Galactic center. Previously stellar…
Evolution of Quasi-Periodic Eruptions in the post-TDE Accretion Disk Perturbed by an Orbiting Star
Martin Mondek, Michal Zajaček, Henry Best +3
Quasi-periodic eruptions (QPEs) are a recently discovered class of highly variable X-ray bursts originating in galactic nuclei. These high-amplitude bursts exhibit periodicity rang…
Non-orbital particle trapping in binary black holes through dynamic stability
Ali Kurmus, Michal Zajacek, Greg Kestin +1
We present an interdisciplinary comparison between binary black hole systems and Radio Frequency (RF) Paul Traps, modeling the gravitational binary system as a rotating saddle near…
High-cadence observations of galactic nuclei by the future two-band UV-photometry mission QUVIK
Michal Zajaček, Norbert Werner, Henry Best +12
The Quick Ultra-VIolet Kilonova surveyor (QUVIK), a two-band UV space telescope approved for funding as a Czech national science and technology mission, will focus on detecting ear…
A binary system in the S cluster close to the supermassive black hole Sagittarius A*
Florian Peißker, Michal Zajacek, Lucas Labadie +4
High-velocity stars and peculiar G objects orbit the central supermassive black hole (SMBH) Sagittarius A* (Sgr A*). Together, the G objects and high-velocity stars constitute the…
Discovery of a Dense Association of Stars in the Vicinity of the Supermassive Black Hole Sgr A*
S. Elaheh Hosseini, Andreas Eckart, Michal Zajaček +3
We focus on a sample of 42 sources in the vicinity of the bow-shock source IRS 1W (N-sources), located at the distance of north-east of the supermassive black hole (SMBH)…
Repeated Partial Tidal Disruptions and Quasi-Periodic Eruptions in SwJ023017.0+283603
Dheeraj Pasham, Eric Coughlin, Chris Nixon +5
SwJ023017.0+283603 (SwJ0230) exhibited soft X-ray (0.3-1.0 keV) eruptions recurring roughly every 22 days. We present results from an extended monitoring campaign of SwJ0230 using…
The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure
Florian Peißker, Michal Zajacek, Matus Labaj +8
The existence of two distinct and apparently unrelated populations of dusty stellar objects in the Nuclear Stellar Cluster (NSC) of the Milky Way, namely IRS 13 and the S-cluster,…
Candidate Young Stellar Objects in the S-cluster: The Kinematic Analysis of a Sub-population of the Low-mass G-objects close to Sgr A*
Florian Peißker, Michal Zajaček, Maria Melamed +5
The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty ob…
Repeating Nuclear Transients as Candidate Electromagnetic Counterparts of LISA Extreme Mass Ratio Inspirals
Shubham Kejriwal, Vojtech Witzany, Michal Zajacek +2
Extreme-mass-ratio inspirals (EMRIs) are one of the primary targets for the recently adopted millihertz gravitational-wave (GW) observatory LISA. Some previous studies have argued…
A Case for a Binary Black Hole System Revealed via Quasi-Periodic Outflows
Dheeraj R. Pasham, Francesco Tombesi, Petra Sukova +33
Binaries containing a compact object orbiting a supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely chall…
Alive but Barely Kicking: News from 3+ years of Swift and XMM-Newton X-ray Monitoring of Quasi-Periodic Eruptions from eRO-QPE1
Dheeraj R. Pasham, Eric R. Coughlin, Michal Zajacek +11
Quasi-periodic Eruptions (QPEs) represent a novel class of extragalactic X-ray transients that are known to repeat at roughly regular intervals of a few hours to days. Their underl…
Lense-Thirring Precession after a Supermassive Black Hole Disrupts a Star
Dheeraj R. Pasham, Michal Zajacek, C. J. Nixon +8
An accretion disk formed around a supermassive black hole (SMBH) after it disrupts a star is expected to be initially misaligned with respect to the black hole's equatorial plane.…
New theoretical Fe II templates for bright quasars
Ashwani Pandey, Mary Loli Martínez-Aldama, Bożena Czerny +5
We present a set of new theoretical Fe II templates for bright quasars covering a wavelength range of 1000-10000 Å\, based on the recent atomic database available in the C23.00 ver…
MAD UFOs: Magnetically Arrested Discs with persistent Ultra-Fast Outflows
Petra Suková, Michal Zajaček, Vladimír Karas
General-relativistic magneto-hydrodynamical (GRMHD) simulations of accreting black holes suggest that the accretion flows form toroidal structures embedded in a large scale compone…
Broad-line region in active galactic nuclei: Dusty or dustless?
Ashwani Pandey, Bozena Czerny, Swayamtrupta Panda +5
Context. Dust in active galactic nuclei is clearly present right outside the broad-line region (BLR) in the form of a dusty molecular torus. However, some models of the BLR predict…
The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a rich population of dusty objects in the IRS 13 cluster
Florian Peißker, Michal Zajaček, Lauritz Thomkins +6
A detailed analysis of the Nuclear Stellar Cluster (NSC) concedes not only the existence of the Scluster with its fast-moving stars and the supermassive black hole (SMBH) Sgr A*. I…
X-ray eruptions every 22 days from the nucleus of a nearby galaxy
Muryel Guolo, Dheeraj R. Pasham, Michal Zajaček +15
Galactic nuclei showing recurrent phases of activity and quiescence have recently been discovered, with recurrence times as short as a few hours to a day -- known as quasi-periodic…
Precession-induced Variability in AGN Jets and OJ 287
Silke Britzen, Michal Zajaček, Gopal-Krishna +5
The combined study of the flaring of Active Galactic Nuclei (AGN) at radio wavelengths and pc-scale jet kinematics with Very Long Baseline Interferometry (VLBI) has led to the view…