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We present full-polarization observations at $\lambda = 0.87$ mm (345 GHz) conducted with the Atacama Large Millimeter/submillimeter Array (ALMA) toward Messier 87 (M87) and seven other radio-loud active galactic nuclei (AGN). We determine…

Astrophysics of Galaxies · Physics 2025-07-23 Ciriaco Goddi , Douglas F. Carlos

Fast radio bursts (FRBs) are bright radio bursts originating at cosmological distances. Only three repeating FRBs FRB 20121102A, FRB 20190520B and FRB 20201124A among $\sim$ 60 known repeating FRBs have circular polarization. We observed…

The absolute position of the compact radio source at the dynamical center of the Galaxy, Sgr A$^*$, was known only to an accuracy of $0.2''$ in spite of its accurate location with respect to near-IR stellar sources to within 30…

Astrophysics · Physics 2009-10-31 F. Yusef-Zadeh , D. Choate , W. Cotton

Observations of the optical polarization of NGC 4151 in 1997-2003 show variations of an order of magnitude in the polarized flux while the polarization position angle remains constant. The amplitude of variability of the polarized flux is…

We present deep VLA observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.6" and 10". At 1.6", we find that the peak flux cumulative number count distribution is N($>$p) $\sim$ 45 *…

Astrophysics of Galaxies · Physics 2014-03-31 Lawrence Rudnick , Frazer Owen

Millimeter wavelength polarimetry of accreting black hole systems can provide a tomographic probe of the accretion flow on a wide range of linear scales. We searched for linear polarization in two low luminosity active galactic nuclei…

High Energy Astrophysical Phenomena · Physics 2017-12-08 Geoffrey C. Bower , Jason Dexter , Sera Markoff , Ramprasad Rao , R. L. Plambeck

We describe the results of a mJy-sensitivity, VLA survey of roughly 1 square degree near the Galactic center at 6 and 20 cm. Catalogs of compact and filamentary structures are given and compared to previous surveys of the region. Eight of…

Astrophysics · Physics 2009-11-13 C. J. Law , F. Yusef-Zadeh , W. D. Cotton

Using the Submillimeter Array, we have made the first high angular resolution measurements of the linear polarization of Sagittarius A* at submillimeter wavelengths, and the first detection of intra-day variability in its linear…

Astrophysics · Physics 2009-11-13 D. P. Marrone , J. M. Moran , J. -H. Zhao , R. Rao

We summarize previous VLBI observations of Sgr A* at millimeter wavelengths and present new results from VLBI observations at 86 and at 215 GHz. At 86 GHz the measured closure phase is close to zero, consistent with a point-like or…

Astrophysics · Physics 2007-05-23 T. P. Krichbaum , A. Witzel , J. A. Zensus

We present measurements of the polarization of X-rays in the $2-8 \thinspace \mathrm{keV}$ band from the nucleus of the radio galaxy Centaurus A (Cen A), using a 100ks observation from the Imaging X-ray Polarimetry Explorer (IXPE). Nearly…

High Energy Astrophysical Phenomena · Physics 2022-08-31 Steven R. Ehlert , Riccardo Ferrazzoli , Andrea Marinucci , Herman L. Marshall , Riccardo Middei , Luigi Pacciani , Matteo Perri , Pierre-Olivier Petrucci , Simonetta Puccetti , Thibault Barnouin , Stefano Bianchi , Ioannis Liodakis , Grzegorz Madejski , Fréderic Marin , Alan P. Marscher , Giorgio Matt , Juri Poutanen , Kinwah Wu , Iván Agudo , Lucio A. Antonelli , Matteo Bachetti , Luca Baldini , Wayne H. Baumgartner , Ronaldo Bellazzini , Stephen D. Bongiorno , Raffaella Bonino , Alessandro Brez , Niccolò Bucciantini , Fiamma Capitanio , Simone Castellano , Elisabetta Cavazzuti , Stefano Ciprini , Enrico Costa , Alessandra De Rosa , Ettore Del Monte , Laura Di Gesu , Niccolò Di Lalla , Alessandro Di Marco , Immacolata Donnarumma , Victor Doroshenko , Michal Dovčiak , Teruaki Enoto , Yuri Evangelista , Sergio Fabiani , Javier A. Garcia , Shuichi Gunji , Kiyoshi Hayashida , Jeremy Heyl , Wataru Iwakiri , Svetlana G. Jorstad , Vladimir Karas , Takao Kitaguchi , Jeffery J. Kolodziejczak , Henric Krawczynski , Fabio La Monaca , Luca Latronico , Simone Maldera , Alberto Manfreda , Francesco Massaro , Ikuyuki Mitsuishi , Tsunefumi Mizuno , Fabio Muleri , Michela Negro , C. -Y. Ng , Stephen L. O'Dell , Nicola Omodei , Chiara Oppedisano , Alessandro Papitto , George G. Pavlov , Abel L. Peirson , Melissa Pesce-Rollins , Maura Pilia , Andrea Possenti , Brian D. Ramsey , John Rankin , Ajay Ratheesh , Roger W. Romani , Carmelo Sgrò , Patrick Slane , Paolo Soffitta , Gloria Spandre , Toru Tamagawa , Fabrizio Tavecchio , Roberto Taverna , Yuzuru Tawara , Allyn F. Tennant , Nicholas E. Thomas , Francesco Tombesi , Alessio Trois , Sergey Tsygankov , Roberto Turolla , Jacco Vink , Martin C. Weisskopf , Fei Xie , Silvia Zane , James Rodi , Elisabeth Jourdain , Jean-Pierre Roques

In this Letter, we report the discovery of a new bright radio transient in M82. Using the Very Large Array, we observed the nuclear region of M82 at several epochs at 22 GHz and detected a new bright radio source in this galaxy's central…

Cosmology and Nongalactic Astrophysics · Physics 2009-05-28 A. Brunthaler , K. M. Menten , M. J. Reid , C. Henkel , G. C. Bower , H. Falcke

At radio wavelengths, images of the compact radio source Sagittarius A* (Sgr A*) in the Galactic Center are scatter broadened with a lambda^2 dependence due to an intervening ionized medium. We present VLBI observations of Sgr A* at 86 GHz…

We report on new VLA radio observations performed at 1.4 GHz and 4.8 GHz with unprecedented sensitivity and angular resolution (~1 arcsec) of the cool core cluster A 2626, which is known to possess a radio mini-halo at its center. The most…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Myriam Gitti

We report on multi-frequency Very Large Array (VLA) and Very Long Baseline Interferometry (VLBI) radio observations for a monitoring campaign of supernova SN$\,$2008iz in the nearby irregular galaxy M$\,$82. We fit two models to the data, a…

High Energy Astrophysical Phenomena · Physics 2016-08-31 N. Kimani , K. Sendlinger , A. Brunthaler , K. M. Menten , I. Martí-Vidal , C. Henkel , H. Falcke , T. W. B. Muxlow , R. J. Beswick , G. C. Bower

We confirm our earlier tentative detection of M31* in X-rays and measure its light-curve and spectrum. Observations in 2004-2005 find M31* rather quiescent in the X-ray and radio. However, X-ray observations in 2006-2007 and radio…

We use high-quality VLA images of the Fanaroff & Riley Class I radio galaxy 3C 31 at six frequencies in the range 1365 to 8440MHz to explore the spatial scale and origin of the rotation measure (RM) fluctuations on the line of sight to the…

Astrophysics · Physics 2009-11-13 R. A. Laing , A. H. Bridle , P. Parma , M. Murgia

A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz band flux of Sgr A* have been found with the Atacama Large…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Yuhei Iwata , Tomoharu Oka , Masato Tsuboi , Makoto Miyoshi , Shunya Takekawa

A VLA Sky Survey of the extragalactic sky at S band (2-4 GHz) with polarization information can uniquely probe the magneto-ionic medium in a wide range of astrophysical environments over cosmic time. For a shallow all-sky survey, we expect…

In this article we summarise and discuss the infrared, radio, and X-ray emission from the supermassive black hole in the Galactic Centre, SgrA*. We include new results from near-infrared polarimetric imaging observations obtained on May…

Astrophysics · Physics 2008-11-26 S. Trippe , T. Paumard , T. Ott , S. Gillessen , F. Eisenhauer , F. Martins , R. Genzel

We present results from the analysis of deep ROSAT HRI and PSPC observations of the spiral galaxy M81. The inferred total (0.5-2 keV band) luminosity of M81 is ~3x10^40 ergs/s, excluding the contribution from identified interlopers found…

Astrophysics · Physics 2009-11-06 Stefan Immler , Q. Daniel Wang
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