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We used the Australia Telescope in March-April 2005 to observe the RS CVn binary HR 1099 at 1.384 and 2.368 GHz at two epochs, each of 9 h in duration and 11 days apart. During two episodes of coherent emission, we employed a recently…

Astrophysics · Physics 2009-11-13 O. B. Slee , W. Wilson , G. Ramsay

We report the results of a multiwavelength study of the non-thermal radio emitter HD168112 (O5.5III(f^+)). The detailed analysis of two quasi-simultaneous XMM-Newton and VLA observations reveals strong variability of this star both in the…

We report on the first near-simultaneous X-ray and optical observations of RX J0806.3+1527. The source is believed to be a 321s orbital period ultra-compact binary system hosting an X-ray emitting white dwarf. Data were obtained with…

We report deep Karl G. Jansky Very Large Array (VLA) observations of the optically ultraluminous and radio-quiet quasar SDSS J010013.02 + 280225.8 (hereafter J0100+2802) at redshift $z=$6.3. We detected the radio continuum emission at 1.5…

Long-period radio transients are an emerging class of extreme astrophysical events of which only three are known. These objects emit highly polarised, coherent pulses of typically a few tens of seconds duration and minutes to hour-long…

We present the results of a broadband radio-to-GeV observing campaign organized to get a better understanding of the radiation processes responsible for the $\gamma$-ray flares observed in 3C 279. The total intensity and polarization…

High Energy Astrophysical Phenomena · Physics 2016-10-26 B. Rani , T. P. Krichbaum , S. -S. Lee , K. Sokolovsky , S. Kang , D. -Y. Byun , D. Mosunova , J. A. Zensus

In this work, we have carried out a systematic analysis of the VLASS quick look catalogs together with \textit{Gaia DR3} to identify the optical counterparts of 3~GHz radio emitters within 500~pc to obtain a homogeneous statistical sample…

We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz…

High Energy Astrophysical Phenomena · Physics 2019-11-12 F. D'Ammando , C. M. Raiteri , M. Villata , J. A. Acosta-Pulido , I. Agudo , A. A. Arkharov , R. Bachev , G. V. Baida , E. Benitez , G. A. Borman , W. Boschin , V. Bozhilov , M. S. Butuzova , P. Calcidese , M. I. Carnerero , D. Carosati , C. Casadio , N. Castro-Segura , W. -P. Chen , G. Damljanovic , A. Di Paola , J. Echevarria , N. V. Efimova , Sh. A. Ehgamberdiev , C. Espinosa , A. Fuentes , A. Giunta , J. L. Gomez , T. S. Grishina , M. A. Gurwell , D. Hiriart , H. Jermak , B. Jordan , S. G. Jorstad , M. Joshi , G. N. Kimeridze , E. N. Kopatskaya , K. Kuratov , O. M. Kurtanidze , S. O. Kurtanidze , A. Lahteenmaki , V. M. Larionov , E. G. Larionova , L. V. Larionova , C. Lazaro , C. S. Lin , M. P. Malmrose , A. P. Marscher , K. Matsumoto , B. McBreen , R. Michel , B. Mihov , M. Minev , D. O. Mirzaqulov , S. N. Molina , J. W. Moody , D. A. Morozova , S. V. Nazarov , A. A. Nikiforova , M. G. Nikolashvili , J. M. Ohlert , N. Okhmat , E. Ovcharov , F. Pinna , T. A. Polakis , C. Protasio , T. Pursimo , F. J. Redondo-Lorenzo , N. Rizzi , G. Rodriguez-Coira , K. Sadakane , A. C. Sadun , M. R. Samal , S. S. Savchenko , E. Semkov , L. Sigua , B. A. Skiff , L. Slavcheva-Mihova , P. S. Smith , I. A. Steele , A. Strigachev , J. Tammi , C. Thum , M. Tornikoski , Yu. V. Troitskaya , I. S. Troitsky , A. A. Vasilyev , O. Vince , T. Hovatta , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead , R. Reeves , T. J. Pearson , T. Mufakharov , Yu. V. Sotnikova , M. G. Mingaliev

A broadband study of the high redshift blazar S5 0836+71 (z = 2.172) is presented. Multi-frequency light curves show multiple episodes of X-ray and $\gamma$-ray flares, while optical-UV fluxes show little variations. During the GeV…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Vaidehi S. Paliya

We present near-infrared $JHK_s$ photometry and light curves of the candidate magnetic white dwarf+brown dwarf binary SDSS J121209.31+013627.7 and report on the detection of near-infrared excess and variability in the $K_s-$band. The…

Astrophysics · Physics 2009-11-11 J. H. Debes , M. Lopez-Morales , A. Z. Bonanos , A. J. Weinberger

Long-period radio transients are a new class of astrophysical objects that exhibit periodic radio emission on timescales of tens of minutes. Their true nature remains unknown; possibilities include magnetic white dwarfs, binary systems, or…

High Energy Astrophysical Phenomena · Physics 2025-01-22 Yunpeng Men , Sam McSweeney , Natasha Hurley-Walker , Ewan Barr , Ben Stappers

Auroral radio emissions in planetary magnetospheres typically feature highly polarized, intense radio bursts, usually attributed to electron cyclotron maser (ECM) emission from energetic electrons in the planetary polar region that features…

Solar and Stellar Astrophysics · Physics 2023-10-03 Sijie Yu , Bin Chen , Rohit Sharma , Timothy Bastian , Surajit Mondal , Dale Gary , Yingjie Luo , Marina Battaglia

[Abridged] We present an 8.5-hour simultaneous radio, X-ray, UV, and optical observation of the L dwarf binary 2MASSW J0746+20. We detect strong radio emission, dominated by short-duration periodic pulses at 4.86 GHz with P=124.32+/-0.11…

Context. After the detection of a 321-days periodicity in X-rays, HESS J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries. These sources are known to show extended radio structure at scales of…

High Energy Astrophysical Phenomena · Physics 2011-09-06 J. Moldón , M. Ribó , J. M. Paredes

Fast Radio Bursts (FRBs) are bright radio transients with millisecond durations which typically occur at extragalactic distances. The association of FRB 20200428 with the Galactic magnetar SGR J1935+2154 strongly indicates that they could…

High Energy Astrophysical Phenomena · Physics 2024-12-13 Chen Du , Yong-Feng Huang , Zhi-Bin Zhang , Alexander Rodin , Viktoriya Fedorova , Abdusattar Kurban , Di Li

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated gamma-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published…

We report the results of Giant Metrewave Radio Telescope (GMRT) observations of H{\sc i} absorption towards the FRII radio galaxy 3C321 (J1531+2404), which is associated with an active galaxy interacting with a companion. The absorption…

Astrophysics of Galaxies · Physics 2012-08-16 Yogesh Chandola , S. K. Sirothia , D. J. Saikia , Neeraj Gupta

The source CGRaBS~J0211$+$1051 (MG1 J021114+1051, z=0.20) flared up on 2011 January 23 in high-energy $\gamma$-rays as reported by {\it Fermi}/LAT. This event was followed by the increased activity at the UV, optical and radio frequencies…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Sunil Chandra , Kiran S Baliyan , Shashikiran Ganesh , Luigi Foschini

From a series of 5 GHz VLBA radio observations taken over 1-yr span, we present the detection of compact highly-polarized radio emission from the T6 brown dwarf WISE J112254.72+255022.2 compatible with electron cyclotron maser emission.…

Solar and Stellar Astrophysics · Physics 2025-05-08 J. C. Guirado , J. B. Climent , J. D. Bergasa , M. A. Pérez-Torres , J. M. Marcaide , L. Peña-Moñino

[Abridged] As part of our on-going investigation of magnetic activity in ultracool dwarfs we present simultaneous radio, X-ray, UV, and optical observations of LSR1835+32 (M8.5), and simultaneous X-ray and UV observations of VB10 (M8), both…