395 citations · 2.4k across the 119 of their papers we have counts for
56 papers · 1 filter
Milliarcsecond-scale radio structure of the most distant BL Lac object candidate at redshift 6.57
S. Frey, Y. Zhang, K. Perger +7
The existence of accreting supermassive black holes up to billions of solar masses at early cosmological epochs (in the context of this work, redshifts z>=6) requires very fast gro…
From binary to singular: the AGN PSO J334.2028+1.4075 under the high-resolution scope
P. Benke, K. É. Gabányi, S. Frey +6
PSO J334.2028+1.4075 (PSO J334) is a luminous quasar located at redshift z=2.06. The source gained attention when periodic flux density variations were discovered in its optical li…
The Detection of a Compact Radio Feature in a Seyfert Galaxy After an Accretion Rate Change
K. É. Gabányi, K. Smith, S. Frey +3
X-ray binaries are known to show state transitions related to accretion rate changes which are often accompanied with dramatic changes in the jet emission. However, it is not clear…
Astrometric Apparent Motion of High-redshift Radio Sources
Oleg Titov, Sandor Frey, Alexei Melnikov +10
Radio-loud quasars at high redshift (z > 4) are rare objects in the Universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density s…
Intermediate-mass black holes: finding of episodic, large-scale and powerful jet activity in a dwarf galaxy
Jun Yang, Zsolt Paragi, Sándor Frey +10
Dwarf galaxies are characterised by a very low luminosity and low mass. Because of significant accretion and ejection activity of massive black holes, some dwarf galaxies also host…
Very long baseline interferometry observations of the high-redshift blazar candidate J0141-5427
K. É. Gabányi, S. Belladitta, S. Frey +7
Active galactic nuclei (AGN) have been observed as far as redshift z~7. They are crucial in investigating the early Universe as well as the growth of supermassive black holes at th…
High-resolution Imaging of Two Radio Quasars at the End of the Reionization Epoch
Krisztina Perger, Yingkang Zhang, Sándor Frey +7
There are approximately 250 quasars discovered at redshift , of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution ve…
Radio-loud Quasars above Redshift 4: VLBI Imaging of an Extended Sample
M. Krezinger, K. Perger, K. É. Gabányi +7
High-redshift radio sources provide plentiful opportunities for studying the formation and evolution of early galaxies and supermassive black holes. However, the number of known ra…
Searching for the Origin of Double-peaked Broad Emission Lines in a Merging Galaxy with EVN
Krisztina É. Gabányi, Sándor Frey, Emma Kun +2
The current cosmological structure formation models predict that galaxies evolve through frequent mergers. During these events, the supermassive black holes (SMBHs) residing in the…
Unprecedented change in the position of four radio sources
Oleg Titov, Sándor Frey, Sébastien Lambert +7
Astrometric positions of radio-emitting active galactic nuclei (AGNs) can be determined with sub-milliarcsec accuracy using very long baseline interferometry (VLBI). The usually sm…
Three in One: The VLBI Radio View of the X-ray Quasar RX J1456.0+5048
Sándor Frey, Ingrid Tar, Krisztina Perger
RX J1456.0+5048 is a prominent X-ray source detected by ROSAT. There is ~100-mJy level radio emission associated with the X-ray source. However, interferometric observations with i…
A small radio galaxy at z=4.026
Krisztina É. Gabányi, Sándor Frey, Tao An +8
Less than radio-loud active galactic nuclei (AGN) are known above redshift . Around of them have been observed at milliarcsecond (mas) scale resolution with very long…
European VLBI Network Observations of the Proposed Dual AGN SDSS J101022.95+141300.9
Patrik Milán Veres, Krisztina É. Gabányi, Sándor Frey +3
During galaxy merger events, the supermassive black holes in the center of the galaxies may form a pair of active galactic nuclei (AGN) with kpc-scale or even pc-scale separation.…
Radio emission from dust-obscured galaxies
Krisztina É. Gabányi, Sándor Frey, Krisztina Perger
The coevolution of galaxies and their central supermassive black holes is a subject of intense research. A class of objects, the dust-obscured galaxies (DOGs) are particularly inte…
Multi-scale Radio and X-ray Structure of the High-redshift Quasar PMN J0909+0354
Krisztina Perger, Sándor Frey, Daniel A. Schwartz +3
The high-redshift quasar PMN J0909+0354 () is known to have a pc-scale compact jet structure, based on global 5-GHz very long baseline interferometry (VLBI) observations p…
Very Long Baseline Interferometry Observations of the Proposed Radio Counterpart of an EGRET Source
Patrik Milán Veres, Krisztina Éva Gabányi, Sándor Frey
We present high-resolution radio interferometric imaging observations of the radio source NVSS J182659+343113 (hereafter J1826+3431), the proposed radio counterpart of the -ray…
A method for checking high-redshift identification of radio AGNs
Tao An, Yingkang Zhang, Sandor Frey
In large-scale optical spectroscopic surveys, there are many objects found to have multiple redshift measurements due to the weakness of their emission lines and the different auto…
J1110+4817 -- a compact symmetric object candidate revisited
M. Krezinger, S. Frey, T. An +2
Compact symmetric objects (CSOs) are radio-emitting active galactic nuclei (AGNs) typically with a double-lobed radio structure confined to within 1 kpc. CSOs represent the earlies…
High-Resolution Radio Observations of Five Optically Selected Type 2 Quasars
Máté Krezinger, Sándor Frey, Zsolt Paragi +1
Many low-luminosity active galactic nuclei (AGNs) contain a compact radio core which can be observed with high angular resolution using very long baseline interferometry (VLBI). Co…
The Quest for Dual and Binary Supermassive Black Holes: A Multi-Messenger View
Alessandra De Rosa, Cristian Vignali, Tamara Bogdanović +27
The quest for binary and dual supermassive black holes (SMBHs) at the dawn of the multi-messenger era is compelling. Detecting dual active galactic nuclei (AGN) -- active SMBHs at…
Evolving parsec-scale radio structure in the most distant blazar known
Tao An, Prashanth Mohan, Yingkang Zhang +7
Blazars are a sub-class of quasars with Doppler boosted jets oriented close to the line of sight, and thus efficient probes of supermassive black hole growth and their environment,…
Unveiling the weak radio quasar population at z 4
Krisztina Perger, Sándor Frey, Krisztina É. Gabányi +1
We applied image stacking on empty-field Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey maps centred on optically identified high-redshift quasars at t…
Very long baseline interferometry observation of the triple AGN candidate J0849+1114
Krisztina Éva Gabányi, Sándor Frey, Shobita Satyapal +2
In the hierarchical structure formation model, galaxies grow through various merging events. Numerical simulations indicate that the mergers can enhance the activity of the central…
Detection statistics of the RadioAstron AGN survey
Y. Y. Kovalev, N. S. Kardashev, K. V. Sokolovsky +57
The largest Key Science Program of the RadioAstron space VLBI mission is a survey of active galactic nuclei (AGN). The main goal of the survey is to measure and study the brightnes…