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Supermassive black hole binaries (SMBHBs) may exist in the centers of galaxies and active galactic nuclei (AGN) and are expected to be fairly common in the Universe as a consequence of merging processes between galaxies. The existence of…

Astrophysics · Physics 2009-11-10 F. De Paolis , G. Ingrosso , A. A. Nucita

We report on sensitive radio observations made with the VLA at 8.5 GHz, centered on the Hubble Deep Field (HDF). We collected data in the A, CnB, C, DnC, and D configurations, corresponding to angular resolutions ranging from 0.3" to 10".…

We have used the VLBA at 5 GHz to observe all galaxies with nuclear radio flux densities above 3.5 mJy found in a VLA survey at 15 GHz of a sample of nearby LINER galaxies. All galaxies were detected revealing high brightness temperature…

Astrophysics · Physics 2009-10-31 Heino Falcke , Neil M. Nagar , Andrew S. Wilson , James S. Ulvestad

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field. This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of…

Astrophysics · Physics 2009-10-31 E. A. Richards

The discovery of a persistent radio source coincident with the first repeating fast radio burst, FRB 121102, and offset from the center of its dwarf host galaxy has been used as evidence for a link with young millisecond magnetars born in…

High Energy Astrophysical Phenomena · Physics 2020-06-10 T. Eftekhari , E. Berger , B. Margalit , B. D. Metzger , P. K. G. Williams

We have studied the nuclear activity in a sample of six quiescent early-type galaxies, with new Chandra data and archival HST optical images. Their nuclear sources have X-ray luminosities ~ 10^{38} - 10^{39} erg/s (L_X/L_Edd ~ 10^{-8} -…

We analyze radio continuum and line observations from the archives of the Very Large Array, as well as X-ray observations from the \emph{Chandra} archive of the region of massive star formation W75N. Five radio continuum sources are…

Solar and Stellar Astrophysics · Physics 2015-05-18 C. Carrasco-Gonzalez , L. F. Rodriguez , J. M. Torrelles , G. Anglada , O. Gonzalez-Martin

We present a new catalogue of radio sources in the face-on spiral galaxy M83. Radio observations taken in 2011, 2015, and 2017 with the Australia Telescope Compact Array (ATCA) at 5.5 and 9 GHz have detected 270 radio sources. Although a…

Astrophysics of Galaxies · Physics 2020-05-13 Thomas D. Russell , Richard L. White , Knox S. Long , William P. Blair , Roberto Soria , P. Frank Winkler

The large majority of extragalactic very high energy (VHE; E>100 GeV) sources belongs to the class of active galactic nuclei (AGN), in particular the BL Lac sub-class. AGNs are characterized by an extremely bright and compact emission…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-15 Martin Raue , Lukasz Stawarz , Daniel Mazin , Pierre Colin , Michelle Hui , Matthias Beilicke , Craig Walker

The radio emission from Sgr A$^\ast$ is thought to be powered by accretion onto a supermassive black hole of $\sim\! 4\times10^6~ \rm{M}_\odot$ at the Galactic Center. At millimeter wavelengths, Very Long Baseline Interferometry (VLBI)…

Mrk 1018 is a nearby changing-look AGN that has oscillated between spectral Type 1.9 and Type 1 over a period of 40 years. Recently, a recoiling supermassive black hole (rSMBH) scenario has been proposed to explain the spectral and flux…

Astrophysics of Galaxies · Physics 2023-07-26 Gregory Walsh , Sarah Burke-Spolaor , T. Joseph W. Lazio

We report the discovery of a giant radio halo in the galaxy cluster RXC J1514.9-1523 at z=0.22 with a relatively low X-ray luminosity, $L_{X \, [0.1-2.4 \rm \, kev]} \sim 7 \times 10^{44}$ erg s$^{-1}$. This faint, diffuse radio source is…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Simona Giacintucci , Daniele Dallacasa , Tiziana Venturi , Gianfranco Brunetti , Rossella Cassano , Maxim Markevitch , Ramana M. Athreya

We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at lambda=20 cm (nu=1.4 GHz) from archived VLA observations. In total, we identify a collection of 916…

Astrophysics of Galaxies · Physics 2015-06-22 T. J. Galvin , M. D. Filipovic

The Quintuplet cluster, located in the Galactic centre, is one of the few young massive clusters in the Milky Way. It allows us to study dozens of massive, post main sequence stars individually, providing unique insights into the properties…

Astrophysics of Galaxies · Physics 2025-07-30 M. Cano-González , R. Schödel , A. Alberdi , J. Moldón , M. Pérez-Torres , F. Najarro , A. T. Gallego-Calvente

The Andromeda galaxy (M31) hosts a central super-massive black hole (SMBH), known as M31$^\ast$, which is remarkable for its mass ($\sim$$10^8{\rm~M_\odot}$) and extreme radiative quiescence. Over the past decade, the Chandra X-ray…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Zhiyuan Li , Michael R. Garcia , William R. Forman , Christine Jones , Ralph P. Kraft , Dharam V. Lal , Stephen S. Murray , Q. Daniel Wang

Our VLA observations of the XMM-Newton/Chandra 13hr deep survey field (see Page et al., this proceedings) result in one of the two deepest 1.4GHz radio maps ever made. Within the 15' radius field covered by the deep X-ray data (0.19 sq…

The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821 hosts an extreme example of a quiescent central massive black hole, for which deep Chandra observations revealed a nuclear source for the first time (with L(2-10 keV)/L_Edd…

Astrophysics · Physics 2015-06-24 S. Pellegrini , A. Siemiginowska , G. Fabbiano , M. Elvis , L. Greenhill , R. Soria , A. Baldi , D. W. Kim

Supermassive black holes (SMBHs) are found ubiquitously in large, bulge-dominated galaxies throughout the local universe, yet little is known about their presence and properties in bulgeless and low-mass galaxies. This is a significant…

While unobscured and radio-quiet active galactic nuclei are regularly being found at redshifts $z > 6$, their obscured and radio-loud counterparts remain elusive. We build upon our successful pilot study, presenting a new sample of…

The nearby (d=3.6 Mpc) starburst galaxy M82 has been studied for several decades by very long baseline interferometry (VLBI) networks such as e-MERLIN and the European VLBI Network (EVN). The numerous supernova remnants (SNRs), HII regions…

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