S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit—S4711 on a 7.6 yr Orbit around Sgr A

F Peißker, A Eckart, M Zajaček, B Ali… - The Astrophysical …, 2020 - iopscience.iop.org
We present high-pass filtered NACO and SINFONI images of the newly discovered stars
S4711–S4715 between 2004 and 2016. Our deep H+K-band (SINFONI) and K-band …

X-ray eruptions every 22 days from the nucleus of a nearby galaxy

M Guolo, DR Pasham, M Zajaček, ER Coughlin… - Nature …, 2024 - nature.com
Galactic nuclei showing recurrent phases of activity and quiescence have recently been
discovered. Some have recurrence times as short as a few hours to a day and are known as …

Stellar transits across a magnetized accretion torus as a mechanism for plasmoid ejection

P Suková, M Zajaček, V Witzany… - The Astrophysical …, 2021 - iopscience.iop.org
The close neighborhood of a supermassive black hole contains not only the accreting gas
and dust but also stellar-sized objects, such as late-type and early-type stars and compact …

Science with a small two-band UV-photometry mission III: Active Galactic Nuclei and nuclear transients

M Zajaček, B Czerny, VK Jaiswal, M Štolc… - Space Science …, 2024 - Springer
In this review, the third one in the series focused on a small two-band UV-photometry
mission, we assess possibilities for a small UV two-band photometry mission in studying …

Standardizing reverberation-measured C iv time-lag quasars, and using them with standardized Mg ii quasars to constrain cosmological parameters

S Cao, M Zajaček, S Panda… - Monthly Notices of …, 2022 - academic.oup.com
We use 38 C iv quasar (QSO) reverberation-mapped observations, which span eight orders
of magnitude in luminosity and the redshift range 0.001064≤ z≤ 3.368, to simultaneously …

Effect of extinction on quasar luminosity distances determined from UV and X-ray flux measurements

M Zajaček, B Czerny, N Khadka… - The Astrophysical …, 2024 - iopscience.iop.org
In Khadka et al., a sample of X-ray-detected reverberation-mapped quasars was presented
and applied for the comparison of cosmological constraints inferred using two well …

A binary system in the S cluster close to the supermassive black hole Sagittarius A

F Peißker, M Zajaček, L Labadie, E Bordier… - Nature …, 2024 - nature.com
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 S …

Detection of galactic center source G2 at 3.8 μm during periapse passage

G Witzel, AM Ghez, MR Morris… - The Astrophysical …, 2014 - iopscience.iop.org
We report new observations of the Galactic Center source G2 from the WM Keck
Observatory. G2 is a dusty red object associated with gas that shows tidal interactions as it …

Detection of a drag force in G2's orbit: Measuring the density of the accretion flow onto Sgr A* at 1000 Schwarzschild radii

S Gillessen, PM Plewa, F Widmann… - The Astrophysical …, 2019 - iopscience.iop.org
Abstract The Galactic Center black hole Sgr A* is the archetypical example of an underfed
massive black hole. The extremely low accretion rate can be understood in radiatively …

Effect of electromagnetic interaction on galactic center flare components

A Tursunov, M Zajaček, A Eckart, M Kološ… - The Astrophysical …, 2020 - iopscience.iop.org
Recently, near-infrared GRAVITY@ ESO observations at 2.2 μm announced the detection of
three bright" flares" in the vicinity of the Galactic center supermassive black hole (SMBH) that …