AT 2018cow VLBI: no long-lived relativistic outflow
| Autor: | Michael Bietenholz, Giacomo Terreran, Dan Milisavljevic, Kate D. Alexander, Edo Berger, Tarraneh Eftekhari, Megan Argo, Raffaella Margutti, Norbert Bartel, Deanne L. Coppejans |
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| Rok vydání: | 2019 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Physics F990 Jet (fluid) Proper motion 010308 nuclear & particles physics FOS: Physical sciences Astronomy and Astrophysics Astrophysics 01 natural sciences Luminosity Tidal disruption event Supernova Space and Planetary Science 0103 physical sciences Very-long-baseline interferometry Outflow Astrophysics - High Energy Astrophysical Phenomena Ejecta 010303 astronomy & astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 491:4735-4741 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | We report on VLBI observations of the fast and blue optical transient (FBOT), AT 2018cow. At ~62 Mpc, AT 2018cow is the first relatively nearby FBOT. The nature of AT 2018cow is not clear, although various hypotheses from a tidal disruption event to different kinds of supernovae have been suggested. It had a very fast rise time (3.5 d) and an almost featureless blue spectrum although high photospheric velocities (40,000 km s$^{-1}$) were suggested early on. The X-ray luminosity was very high, ~$1.4 \times 10^{43}$ erg s$^{-1}$, larger than those of ordinary SNe, and more consistent with those of SNe associated with gamma-ray bursts. Variable hard X-ray emission hints at a long-lived "central engine." It was also fairly radio luminous, with a peak 8.4-GHz spectral luminosity of ~$4 \times 10^{28}$ erg s$^{-1}$ Hz$^{-1}$, allowing us to make VLBI observations at ages between 22 and 287 d. We do not resolve AT 2018cow. Assuming a circularly symmetric source, our observations constrain the average apparent expansion velocity to be Accepted for publication in MNRAS 3 figurs]es |
| Databáze: | OpenAIRE |
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