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A significant minority of high redshift radio galaxy (HzRG) candidates show extremely red broad band colours and remain undetected in emission lines after optical `discovery' spectroscopy. In this paper we present deep GTC optical imaging…

The red damping wing from neutral hydrogen in the intergalactic medium is a smoking-gun signal of ongoing reionization. One potential contaminant of the intergalactic damping wing signal is dense gas associated with foreground galaxies,…

Astrophysics of Galaxies · Physics 2023-12-13 Frederick B. Davies , Eduardo Bañados , Joseph F. Hennawi , Sarah E. I. Bosman

We present the discovery of the radio-loud quasar PSO J352.4034-15.3373 at z=5.84 pm 0.02. This quasar is the radio brightest source known, by an order of magnitude, at z~6 with a flux density in the range of 8-100 mJy from 3GHz to 230MHz…

In the current paradigm, high redshift radio halos are expected to be scarce due to inverse Compton energy losses and redshift dimming, which cause them to be intrinsically faint. This low occurrence fraction is predicted by cosmic ray…

High Energy Astrophysical Phenomena · Physics 2025-06-11 S. P. Sikhosana , M. Hilton , G. Bernardi , K. Kesebonye , D. Y. Klutse , K. Knowles , K. Moodley , T. Mroczkowski , B. Partridge , C. Sifón , C. Vargas , E. Wollack

We report the discovery of a 20-kpc-sized H{\alpha} emission in SDSS J083803.68+540642.0, a ringed dwarf galaxy (M$_V$ = -17.89 mag) hosting an accreting intermediate-mass black hole at z=0.02957. Analysis of the HST images indicates that…

Astrophysics of Galaxies · Physics 2017-03-15 Wen-Juan Liu , Lei Qian , Xiao-Bo Dong , Ning Jiang , Paulina Lira , Zheng Cai , Feige Wang , Jinyi Yang , Ting Xiao , Minjin Kim

We report a new double-double radio quasar, DDRQ, J0746$+$4526 which exhibits two cycles of episodic activity. From radio continuum observations at 607 MHz using the GMRT and 1400 MHz from the FIRST survey we confirm its episodic nature. We…

Astrophysics of Galaxies · Physics 2015-06-19 S. Nandi , R. Roy , D. J. Saikia , M. Singh , H. C. Chandola , M. Baes , R. Joshi , G. Gentile , M. Patgiri

We carry out a series of deep Karl G. Jansky Very Large Array (VLA) S-band observations of a sample of 21 quasars at $z\sim6$. The new observations expand the searches of radio continuum emission to the optically faint quasar population at…

Context: The highest redshift quasars at z>~6 receive considerable attention since they provide strong constraints on the growth of the earliest supermassive black holes. They also probe the epoch of reionisation and serve as "lighthouses"…

Astrophysics · Physics 2008-06-10 S. Frey , L. I. Gurvits , Z. Paragi , K. E. Gabanyi

Relativistic jets are thought to play a crucial role in the formation and evolution of massive galaxies and supermassive black holes. Blazars, which are quasars with jets aligned along our line of sight, provide insights into the jetted…

We present the discovery of a candidate of giant radio-quiet Lyman-alpha (Lya) blob (RQLAB) in a large-scale structure around a high-redshift radio galaxy (HzRG) lying in a giant Lya halo, B3 J2330+3927 at redshift z=3.087. We obtained Lya…

We present new spectroscopic observations of two high redshift radio galaxies, TXS 0211-122 (z=2.34) and TXS 0828+193 (z=2.57), known to be associated with large Ly$\alpha$ halos. The observations were taken with the slits placed…

Q0151+048 is a physical QSO pair at z ~ 1.929 with a separation of 3.3 arcsec on the sky. In the spectrum of Q0151+048A (qA), a DLA is observed at a higher redshift. We have previously detected the host galaxies of both QSOs, as well as a…

The recent discovery of a 4 $\times$ 10$^7$ M$_{\odot}$ black hole (BH) in UHZ1 at $z =$ 10.3, just 450 Myr after the big bang, suggests that the seeds of the first quasars may have been direct-collapse black holes (DCBHs) from the collapse…

Astrophysics of Galaxies · Physics 2023-09-12 Daniel J. Whalen , Muhammad A. Latif , Mar Mezcua

A five square arcminute region around the luminous radio-loud quasar SDSS J0836+0054 (z=5.8) hosts a wealth of associated galaxies, characterized by very red (1.3 < i_775 - z_{850} < 2.0) color. The surface density of these z~5.8 candidates…

Diffuse radio sources, known as mini-halos and halos, are detected at the centres of galaxy clusters. These centralized diffuse sources are typically observed individually, with both appearing together only in rare cases. The origin of the…

High Energy Astrophysical Phenomena · Physics 2025-03-26 D. N. Hoang , M. Brüggen , A. Bonafede , P. M. Koch , G. Brunetti , E. Bulbul , G. Di Gennaro , A. Liu , C. J. Riseley , H. J. A. Röttgering , R. J. van Weeren

The intense UV radiation from a highly luminous QSO should excite fluorescent Ly-alpha emission from any nearby neutral hydrogen clouds. We present a very deep narrow-band search for such emission near the z=2.168 quasar PKS 0424-131,…

Astrophysics · Physics 2011-03-10 Paul J. Francis , Joss Bland-Hawthorn

The high redshift radio galaxy 4C41.17 consists of a powerful radio source in which previous work has shown that there is strong evidence for jet-induced star formation along the radio axis. We argue that nuclear photoionization is not…

We present the discovery of a radio galaxy at a likely redshift of z = 4.424 in one of the flanking fields of the Hubble Deep Field. Radio observations with the VLA and MERLIN centered on the HDF yielded a complete sample of microjansky…

Astrophysics · Physics 2009-10-31 I. Waddington , R. A. Windhorst , S. H. Cohen , R. B. Partridge , H. Spinrad , D. Stern

Quasars at redshifts $z>6$ are an excellent probe of the formation and evolution of supermassive black holes in the early Universe. The population of radio-luminous quasars is of particular interest, as such quasars could potentially be…

Astrophysics of Galaxies · Physics 2024-02-15 Pascal M. Keller , Nithyanandan Thyagarajan , Ajay Kumar , Nissim Kanekar , Gianni Bernardi