Please use this identifier to cite or link to this item:
Title: Late time multi wavelength observations of Swift J1644+5734 : A luminous optical/IR bump and quiescent X-ray emission
Authors: Levan, A. J.
Tanvir, Nial R.
Brown, G. C.
Metzger, B. D.
Page, K. L.
Cenko, S. B.
O'Brien, Paul Thomas
Lyman, J. D.
Wiersema, K.
Stanway, E. R.
Fruchter, A. S.
Perley, D. A.
Bloom, J. S.
First Published: 26-Feb-2016
Publisher: IOP Publishing, American Astronomical Society
Citation: Astrophysical Journal, 2016, 819(1), 51
Abstract: We present late-time multi-wavelength observations of Swift J1644+57, suggested to be a relativistic tidal disruption flare (TDF). Our observations extend to >4 years from discovery, and show that 1.4 years after outburst the relativistic jet switched-off on a timescale less than tens of days, corresponding to a power-law decay faster than $t^{-70}$. Beyond this point weak X-rays continue to be detected at an approximately constant luminosity of $L_X \sim 5 \times 10^{42}$ erg s$^{-1}$, and are marginally inconsistent with a continuing decay of $t^{-5/3}$, similar to that seen prior to the switch-off. Host photometry enables us to infer a black hole mass of $M_{BH}=3 \times 10^6$ M$_{\odot}$, consistent with the late time X-ray luminosity arising from sub-Eddington accretion onto the black hole in the form of either an unusually optically faint AGN or a slowly varying phase of the transient. Optical/IR observations show a clear bump in the light curve at timescales of 30-50 days, with a peak magnitude (corrected for host galaxy extinction) of $M_R \sim -22-23$. The luminosity of the bump is significantly higher than seen in other, non-relativistic TDFs and does not match any re-brightening seen at X-ray or radio wavelengths. Its luminosity, light curve shape and spectrum are broadly similar to those seen in superluminous SNe, although subject to large uncertainties in the correction of the significant host extinction. We discuss these observations in the context of both TDF and massive star origins for Swift J1644+5734 and other candidate relativistic tidal flares.
DOI Link: 10.3847/0004-637X/819/1/51
ISSN: 0004-637X
eISSN: 1538-4357
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2016. The American Astronomical Society. All rights reserved. The file associated with this record is distributed under the Creative Commons “Attribution Non-Commercial No Derivatives” licence, further details of which can be found via the following link:
Description: 16 pages, 7 figures
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

Files in This Item:
File Description SizeFormat 
ms1644_revise2.pdfPost-review (final submitted)821.2 kBAdobe PDFView/Open
apj_819_1_51.pdfPublished (publisher PDF)1.54 MBAdobe PDFView/Open

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.