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iPTF16fnl: A Faint and Fast Tidal Disruption Event in an E+A Galaxy

Blagorodnova, N. and Kulkarni, S. R. and Yan, L. and Bue, B. D. and Ho, A. Y. Q. and Kasliwal, M. M. and Laher, R. R. and Lunnan, R. and Masci, F. J. and Neill, J. D. and Walters, R. (2017) iPTF16fnl: A Faint and Fast Tidal Disruption Event in an E+A Galaxy. Astrophysical Journal, 844 (1). Art. No. 46. ISSN 1538-4357.

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We present ground-based and Swift observations of iPTF16fnl, a likely tidal disruption event (TDE) discovered by the intermediate Palomar Transient Factory (iPTF) survey at 66.6 Mpc. The light curve of the object peaked at an absolute mag M_g =- 17.2. The maximum bolometric luminosity (from optical and UV) was L_p ≃ (1.0 ± 0.15) x 10^(43) erg s^(−1), an order of magnitude fainter than any other optical TDE discovered so far. The luminosity in the first 60 days is consistent with an exponential decay, with L ∝ e^(-(t-t_0)/τ, where t_0 = 57631.0 (MJD) and τ ≃ 15 days. The X-ray shows a marginal detection at L_X = 2.4_(-1.1)^(1.9) x 10^(39) erg s^(−1) (Swift X-ray Telescope). No radio counterpart was detected down to 3σ, providing upper limits for monochromatic radio luminosities of vL_v < 2.3 x 10^(36) erg s^(−1) and vL_v < 1.7 x 10^(37) erg s^(−1) (Very Large Array, 6.1 and 22 GHz). The blackbody temperature, obtained from combined Swift UV and optical photometry, shows a constant value of 19,000 K. The transient spectrum at peak is characterized by broad He ii and Hα emission lines, with FWHMs of about 14,000 km s^(−1) and 10,000 km s^(−1), respectively. He i lines are also detected at λλ 5875 and 6678. The spectrum of the host is dominated by strong Balmer absorption lines, which are consistent with a post-starburst (E+A) galaxy with an age of ~650 Myr and solar metallicity. The characteristics of iPTF16fnl make it an outlier on both luminosity and decay timescales, as compared to other optically selected TDEs. The discovery of such a faint optical event suggests a higher rate of tidal disruptions, as low-luminosity events may have gone unnoticed in previous searches.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Blagorodnova, N.0000-0003-0901-1606
Kulkarni, S. R.0000-0001-5390-8563
Yan, L.0000-0003-1710-9339
Bue, B. D.0000-0002-7856-3570
Ho, A. Y. Q.0000-0002-9017-3567
Kasliwal, M. M.0000-0002-5619-4938
Laher, R. R.0000-0003-2451-5482
Lunnan, R.0000-0001-9454-4639
Masci, F. J.0000-0002-8532-9395
Neill, J. D.0000-0002-0466-1119
Walters, R.0000-0002-1835-6078
Additional Information:© 2017 American Astronomical Society. Received 2017 February 17. Accepted 2017 May 24. Published 2017 July 20. This work was supported by the GROWTH project funded by the National Science Foundation under grant No. 1545949. We thank the Gemini Fast Turnaround program (PI: T. Hung). S.G. is supported in part by NSF CAREER grant 1454816 and NASA Swift Cycle 12 grant NNX16AN85G. A.Y.Q.H. was supported by a National Science Foundation Graduate Research Fellowship under grant No. DGE1144469. A.J.C.T. acknowledges support from the Spanish Ministry Project AYA 2015-71718-R. Support for I.A. was provided by NASA through the Einstein Fellowship Program, grant PF6-170148. G.H. is supported by the National Science Foundation (NSF) under grant No. 1313484. This work makes use of observations from the LCO network. G.H. is supported by the National Science Foundation (NSF) under grant No. 1313484. This work makes use of observations from the LCO network. We acknowledge the use of public data from the Swift data archive. The CSS survey is funded by the National Aeronautics and Space Administration under grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grants AST-0909182. L.A.N.L. participation in iPTF was funded by the US Department of Energy as part of the Laboratory Directed Research and Development program. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Part of this work is based on observations obtained at the Gemini observatory under the Fast Turnaround program. The Gran Telescopio Canarias (GTC) is operated on the island of La Palma at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. The James Clerk Maxwell Telescope is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan, Academia Sinica Institute of Astronomy and Astrophysics, the Korea Astronomy and Space Science Institute, the National Astronomical Observatories of China and the Chinese Academy of Sciences (Grant No. XDB09000000), with additional funding support from the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom and Canada. V.A.F. is supported by the Russian Science Foundation under grant 14-50-00043. Facilities: DCT, Gemini North, GTC, Hale, JCMT, Keck:I, Keck:II, LCOGT, PO:1.2m, PO:1.5m, PS1, VLT. Software: AstroPy, EMCEE (Foreman-Mackey et al. 2013), IRAF, LMFIT, pPXF (Cappellari 2017), PTFIDE (Masci et al. 2017), PYRAF, UVOTSOURCE.
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory, Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Ministerio de Economía, Industria y Competitividad (MINECO)AYA 2015-71718-R
NASA Einstein FellowshipPF6-170148
Department of Energy (DOE)UNSPECIFIED
Chinese Academy of SciencesXDB09000000
Science and Technology Facilities Council (STFC)UNSPECIFIED
Russian Science Foundation14-50-00043
Subject Keywords:accretion, accretion disks; black hole physics; galaxies: nuclei; stars: individual (iPTF16fnl)
Issue or Number:1
Record Number:CaltechAUTHORS:20170720-093554732
Persistent URL:
Official Citation:N. Blagorodnova et al 2017 ApJ 844 46
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79247
Deposited By: Ruth Sustaita
Deposited On:20 Jul 2017 19:07
Last Modified:09 Mar 2020 13:19

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