Related papers: The Case for a Misaligned Relativistic Jet from SN…
The gamma-ray burst (GRB) 060218 has ~ 10^5 times lower luminosity than typical long GRBs, and is associated with a supernova (SN). The radio afterglow displays no jet break, so that this burst might arise from a mildly-relativistic…
We present late-time radio observations of 68 local Type Ibc supernovae, including six events with broad optical absorption lines (``hypernovae''). None of these objects exhibit radio emission attributable to off-axis gamma-ray burst jets…
The dividing line between gamma-ray bursts (GRBs) and ordinary stripped-envelope core-collapse supernovae (SNe) is yet to be fully understood. Observationally mapping the variety of ejecta outcomes (ultra-relativistic, mildly-relativistic…
Recently a Type Ic supernova, SN 1998bw, was discovered coincident with a gamma-ray burst, GRB 980425. The supernova had unusual radio, optical, and spectroscopic properties. We explore here models based upon helium stars in the range 9 -…
Decades have passed since the first confirmed association between a broad-lined Type Ic supernova (Type IcBL SN) and a long gamma-ray burst (GRB), and the number of known GRB-SN associations has steadily increased. However, it is important…
We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived ($t_j \sim 3000$ s) central engine and accompanying…
Study of the polarization of supernovae has suggested that the core collapse process may be intrinsically strongly asymmetric. There is a tentative trend for supernova with smaller envelopes showing more polarization, with Type Ic having…
A persistent, thin, micro-nano sr. beamed gamma jet, may be ejected from BH and Pulsars, powered by ultra-relativistic electron pairs. These jet while precessing and spinning are originated by Inverse Compton and-or Synchrotron Radiation at…
Superluminous supernovae (SLSNe) radiate $\gtrsim 10-100$ times more energy than ordinary stellar explosions, implicating a novel power source behind these enigmatic events. One frequently discussed source, particularly for hydrogen-poor…
Supernovae 1998bw and its corresponding relativistically expanding radio source are coincident with the \grb source GRB 980425. We show that of six recent SN Ib/c for which an outburst epoch can be estimated with some reliability, four have…
Relativistic supernovae constitute a sub-class of type Ic supernovae (SNe). Their non-thermal, radio emission differs notably from that of regular type Ic supernovae as they have a fast expansion speed (with velocities $\sim$ 0.6-0.8 c)…
We show that asymmetries in total intensity and linear polarization between the radio jets and counter-jets in two lobed Fanaroff-Riley Class I (FR I) radio galaxies, B2 0206+35 (UGC 1651) and B2 0755+37 (NGC 2484), can be accounted for if…
We report on VLBI, as well as VLA radio observations of the Type Ib/c supernova 2009bb. The high radio luminosity of this supernova seems to require relativistic outflow, implying that the early radio emission was "engine-driven", that is…
Multiple observational lines of evidence support a connection between hydrogen-poor superluminous supernovae (SLSNe) and long duration gamma-ray bursts (GRBs). Both events require a powerful central energy source, usually attributed to a…
Over the past few years, long-duration gamma-ray bursts (GRBs), including the subclass of X-ray flashes (XRFs), have been revealed to be a rare variety of Type Ibc supernova (SN Ibc). While all these events result from the death of massive…
We present extensive radio and X-ray observations of the nearby Type Ic SN 2007gr in NGC 1058 obtained with the Very Large Array and the Chandra X-ray Observatory and spanning 5 to 150 days after explosion. Through our detailed modeling of…
We report the serendipitous discovery of a supernova (SN) in the nearby radio-galaxy 3C 78. Observations obtained with the STIS spectrograph on board the Hubble Space Telescope show, at a distance of 0.54 arcsec (300 pc) from the galaxy…
We report observations of the optical counterpart of the long gamma-ray burst (LGRB) GRB 221009A. Due to the extreme rarity of being both nearby ($z = 0.151$) and highly energetic ($E_{\gamma,\mathrm{iso}} \geq 10^{54}$ erg), GRB 221009A…
Precessing relativistic jets launched by compact objects are rarely directly measured, and present an invaluable opportunity to better understand many features of astrophysical jets. In this Letter we present MeerKAT radio observations of…
Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the sub-parsec central…