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Related papers: Variability of Late-time Radio Emission in SLSN PT…

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We study the emission of the short/hard GRB 090510 at energies > 0.1 GeV as observed by the Large Area Telescope (LAT) onboard the Fermi satellite. The GeV flux rises in time as t^2 and decays as t^-1.5 up to 200 s. The peak of the high…

High Energy Astrophysical Phenomena · Physics 2015-05-14 G. Ghirlanda , G. Ghisellini , L. Nava

The mJy variable extragalactic radio sky is known to be broadly non-changing with approximately $3\%$ of persistent radio sources exhibiting variability which is largely AGN-related. In the faint (<mJy) flux density regime, it is widely…

We present VLA observations of 16 Type IIn and Type II-L supernovae (SNe IIn and SNe II-L) at ~1000--7000 days after explosion, probing circumstellar matter (CSM) at distances >10^16 cm from the progenitor corresponding to mass-loss over…

High Energy Astrophysical Phenomena · Physics 2026-05-19 Charles D. Kilpatrick , Lindsay DeMarchi , Wen-fai Fong , Jennifer E. Andrews , Ori D. Fox , Nathan Smith

We detect radio emission in an additional two epochs of the ultracool dwarf binary LP 349- 25, finding that the observed emission is broadband and steady on timescales between 10s and 10.7 hours, as well as on timescales of 0.6 and 1.6…

Solar and Stellar Astrophysics · Physics 2009-07-24 R. A. Osten , N. Phan-Bao , S. L. Hawley , I. Neill Reid , R. Ojha

We perform a systematic search of quasi-periodic variabilities in $\gamma$-ray active galactic nuclei (AGNs) in the third \emph{Fermi} Large Area Telescope source catalog (3FGL). We employe two techniques, Lomb-Scargle Periodogram (LSP) and…

High Energy Astrophysical Phenomena · Physics 2020-03-25 Pengfei Zhang , Dahai Yan , Jianeng Zhou , Jiancheng Wang , Li Zhang

The origin of the radio emission in active galactic nuclei (AGN) is still debated. Multiple physical mechanisms can contribute to the spectrum at these frequencies, including relativistic jets, the jet base, outflows, star formation, and…

High Energy Astrophysical Phenomena · Physics 2026-04-01 M. Berton , E. Järvelä , S. Chen , L. Crepaldi , I. Varglund , M. Coloma Puga , A. Jimenez-Gallardo , A. Lähteenmäki , S. Panda , C. Piscitelli , A. Tortosa

We report our discovery and early time optical, near-infrared, and radio wavelength follow-up observations of the afterglow of the gamma-ray burst GRB 021211. Our optical observations, beginning 21 min after the burst trigger, demonstrate…

Optical and near-infrared observations of the gamma-ray burst GRB 031203, at z = 0.1055, are reported. A very faint afterglow is detected superimposed to the host galaxy in our first infrared JHK observations, carried out ~9 hours after the…

We study the variability properties at radio frequencies of the jets thought to be typical of Active Galactic Nuclei, i.e. bulk Lorentz factor \Gamma ~ 10, and incoherent synchrotron emission. We assume that the radiating electrons are…

Astrophysics · Physics 2009-10-30 M. Spada , M. Salvati , F. Pacini

LS I +61 303 is a gamma-ray binary that exhibits an outburst at GHz frequencies each orbital cycle of $\approx$ 26.5 d and a superorbital modulation with a period of $\approx$ 4.6 yr. We have performed a detailed study of the low-frequency…

We report the flux densities of the evolving radio source SN1987A at 843 MHz measured from observations made with the Molonglo Observatory Synthesis Telescope between 1994 September and 2000 May. The radio light curve shows that the rate of…

Astrophysics · Physics 2009-10-31 Lewis Ball , D. F. Crawford , R. W. Hunstead , I. Klamer , V. J. McIntyre

We have formed a new sample which consists of extended extragalactic radio sources without obvious active galactic nuclei (AGN) in them. Most of these sources appear to be dead double radio sources. These sources with steep spectra ($\alpha…

Astrophysics of Galaxies · Physics 2011-02-11 K. S. Dwarakanath , Ruta Kale

We present a three epoch survey for transient and variables in the extended Chandra Deep Field South at 5.5 GHz with the Australia Telescope Compact Array. A region covering $\sim$0.3 deg$^{2}$ was observed on timescales of 2.5 months and…

Astrophysics of Galaxies · Physics 2015-06-17 M. E. Bell , M. T. Huynh , P. Hancock , Tara Murphy , B. M. Gaensler , D. Burlon , C. Trott , K. Bannister

The peculiar supernova (SN) 2009ip is an ambiguous event that spurred many questions regarding its true origins. Here, we present very late-time spectroscopic and photometric observations of SN 2009ip, obtained 9 years (3274 days) after the…

Solar and Stellar Astrophysics · Physics 2023-10-02 Thallis Pessi , Jose L. Prieto , Luc Dessart

We present and discuss the results of VLBI (EVN) observations of three low-luminosity (P(5 GHz)<10^25 W/Hz) Broad Emission Line AGNs carefully selected from a sample of flat spectrum radio sources (CLASS). Based on the total and the…

Astrophysics · Physics 2009-11-07 A. Caccianiga , M. J. M. Marcha , A. Thean , J. Dennett-Thorpe

We present late-time ($\delta t > 3000$ d) optical (Keck), X-ray (Chandra and NuSTAR), and radio (VLA, ALMA, and the uGMRT) observations of the Type Ic-BL SN 2012ap. Previous studies of this SN suggested that it stands out as a key example…

The optically variable source SDSS J124602.54+011318.8 first appears in Sloan Digital Sky Survey (SDSS) data as a bright point source with nonstellar colors. Subsequent SDSS imaging and spectroscopy showed that the point source declined or…

Astrophysics · Physics 2009-11-07 Avishay Gal-Yam , Eran O. Ofek , Alexei V. Filippenko , Ryan Chornock , Weidong Li

We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst of the past 29 years. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z=0.340, indicating…

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