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Ho, AYQ, Phinney, ES, Ravi, V, Kulkarni, SR, Petitpas, G, Emonts, B, Bhalerao, V, Blundell, R, Cenko, SB, Dobie, D, Howie, R, Kamraj, N, Kasliwal, MM, Murphy, T, Perley, DA, Sridharan, TK and Yoon, I (2019) AT2018cow: A Luminous Millimeter Transient. Astrophysical Journal, 871 (1). ISSN 0004-637X
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Abstract
We present detailed submillimeter- through centimeter-wave observations of the extraordinary extragalactic transient AT2018cow. The apparent characteristics—the high radio luminosity, the rise and long-lived emission plateau at millimeter bands, and the sub-relativistic velocity—have no precedent. A basic interpretation of the data suggests ${E}_{k}\gtrsim 4\,\times \,{10}^{48}\,\mathrm{erg}$ coupled to a fast but sub-relativistic ($v\approx 0.13c$) shock in a dense (${n}_{e}\approx 3\,\times \,{10}^{5}\,{\mathrm{cm}}^{-3}$) medium. We find that the X-ray emission is not naturally explained by an extension of the radio-submm synchrotron spectrum, nor by inverse Compton scattering of the dominant blackbody UV/optical/IR photons by energetic electrons within the forward shock. By ${\rm{\Delta }}t\approx 20\,\mathrm{days}$, the X-ray emission shows spectral softening and erratic inter-day variability. Taken together, we are led to invoke an additional source of X-ray emission: the central engine of the event. Regardless of the nature of this central engine, this source heralds a new class of energetic transients shocking a dense medium, which at early times are most readily observed at millimeter wavelengths.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (incl. Structural) |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society; IOP Publishing |
| Related URLs: | |
| Date of acceptance: | 26 November 2018 |
| Date of first compliant Open Access: | 14 September 2020 |
| Date Deposited: | 22 Feb 2019 08:59 |
| Last Modified: | 04 Sep 2021 09:43 |
| DOI or ID number: | 10.3847/1538-4357/aaf473 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/10195 |
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