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We report the first detection of GeV gamma-ray flaring activity from the compact symmetric object (CSO)-like source 4C 76.03, based on 17 years of Fermi-LAT observations. Its long-term, time-averaged gamma-ray properties are consistent with…

High Energy Astrophysical Phenomena · Physics 2026-03-24 Xiong Jiang , Hai Lei , Hao-Yi Huang , Wei Zhang , Yang-Ji Li , Da-Ming Wei

We present the results of the first X-ray study of a sample of 16 young radio sources classified as Compact Symmetric Objects (CSOs). We observed six of them for the first time in X-rays using {\it Chandra}, re-observed four with the…

We present full polarization Very Long Baseline Array (VLBA) observations at 5 GHz and 15 GHz of 24 compact active galactic nuclei (AGN). These sources were observed as part of a pilot project to demonstrate the feasibility of conducting a…

The NRAO Very Long Baseline Array (VLBA) was used at 1.4 GHz to image 20 compact sources in the inner 1-degree radius of the Spitzer VLA First-Look Survey. Twelve sources were detected with the VLBA, with peak flux densities above 2 mJy at…

Astrophysics · Physics 2009-11-10 J. M. Wrobel , M. A. Garrett , J. J. Condon , R. Morganti

We present the results of two (101 ks total) Chandra observations of the z=0.778 optically selected lensing cluster RCS022434-0002.5, along with weak lensing and dynamical analyses of this object. An X-ray spectrum extracted within R(2500)…

The $\gamma$-ray bright blazar CTA 102 is studied using imaging (new 15 GHz and archival 43 GHz Very Long Baseline Array, VLBA data) and time variable optical flux density, polarization degree and electric vector position angle (EVPA)…

High Energy Astrophysical Phenomena · Physics 2018-02-21 Xiaofeng Li , P. Mohan , T. An , Xiaoyu Hong , Xiaopeng Cheng , Jun Yang , Yingkang Zhang , Zhongli Zhang , Wei Zhao

We present new proper motion measurements of optically emitting oxygen-rich knots of supernova remnant 1E 0102.2-7219 (E0102), which are used to estimate the remnant's center of expansion and age. Four epochs of high resolution Hubble Space…

The radio components associated with the LMXB Sco X-1 have been monitored with extensive VLBI imaging at 1.7 and 5.0 GHz over four years, including a 56-hour continuous VLBI observation in 1999 June. We often detected one strong and one…

Astrophysics · Physics 2009-11-06 E. B. Fomalont , B. J. Geldzahler , C. F. Bradshaw

As part our investigation into the Galactic rotation curve, we carried out Very Long Baseline Interferometry (VLBI) observations towards the star-forming region IRAS 01123+6430 using VLBI Exploration of Radio Astrometry (VERA) to measure…

Adaptive Optics observations have dramatically improved the quality and versatility of high angular resolution measurements of the center of our Galaxy. In this paper, we quantify the quality of our Adaptive Optics observations and report…

Astrophysics of Galaxies · Physics 2015-06-11 S. Yelda , A. M. Ghez , J. R. Lu , T. Do , L. Meyer , M. R. Morris

In the last years, the persistent source 1E 1743.1-2843 has been observed in the X-rays, but never above 20 keV. In previous works, it was stressed that a possible high energy emission could give further indications on the accreting object…

Astrophysics · Physics 2009-11-11 M. Del Santo , L. Sidoli , A. Bazzano , M. Cocchi , G. De Cesare , A. Paizis , P. Ubertini

This work presents a detailed study of the gas kinematics towards the "Hot Molecular Core" (HMC) G31.41+0.31 via multi-epoch VLBI observations of the H2O 22 GHz and CH3OH 6.7 GHz masers, and single-epoch VLBI of the OH 1.6 GHz masers. Water…

Solar and Stellar Astrophysics · Physics 2015-06-12 Luca Moscadelli , Jing Jing Li , Riccardo Cesaroni , Alberto Sanna , Ye Xu , Qizhou Zhang

We present the results of a deep (1.1 Ms) observation of the Coma cluster of galaxies in the 18-30 keV band with the IBIS/ISGRI imager on board the INTEGRAL satellite. We show that the source extension in the North-East to South-West (SW)…

Astrophysics · Physics 2007-10-25 D. Eckert , N. Produit , A. Neronov , T. J. -L. Courvoisier

Radio sources with steep spectra are preferentially associated with the most distant galaxies, the $\alpha-z$ relation, but the reason for this relation is an open question. The spatial distribution of spectra in high-z radio sources can be…

Context. Central compact objects (CCOs) are a peculiar class of neutron stars, primarily encountered close to the center of young supernova remnants (SNRs) and characterized by thermal X-ray emission. Aims. Our goal is to perform a…

High Energy Astrophysical Phenomena · Physics 2021-07-14 Martin G. F. Mayer , Werner Becker

Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of the relativistic…

Astrophysics of Galaxies · Physics 2016-08-03 Sang-Sung Lee , Andrei P. Lobanov , Thomas P. Krichbaum , J. Anton Zensus

(abridged) Very long baseline interferometry (VLBI) observations at 86$\,$GHz (wavelength, $\lambda = 3\,$mm) reach a resolution of about 50 $\mu$as, probing the collimation and acceleration regions of relativistic outflows in active…

The FSRQ 4C+01.28 is a bright and highly variable radio and $\gamma$-ray emitter. We aim to pinpoint the location of the $\gamma$-ray emitting region within its jet in order to derive strong constraints on $\gamma$-ray emission models for…

High Energy Astrophysical Phenomena · Physics 2026-01-14 F. Rösch , M. Kadler , E. Ros , L. Ricci , M. A. Gurwell , T. Hovatta , N. R. MacDonald , A. C. S. Readhead

We analyze the results of processing of data of observations which had been carried out with the VLBA during 10 last years. All the data have been retrieved from archive of the National Radio Astronomy Observatory (USA NRAO, Socorro, New…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-06 A. Chuprikov , I. Guirin

We present the results of high resolution VLBI observations at 1.6 and 4.9 GHz of the radio-loud Seyfert galaxy, Mrk 6. These observations are able to detect a compact radio core in this galaxy for the first time. The core has an inverted…

Astrophysics of Galaxies · Physics 2015-06-18 P. Kharb , C. P. O'Dea , S. A. Baum , M. J. Hardcastle , D. Dicken , J. H. Croston , B. Mingo , J. Noel-Storr