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

Abstract

The American Astronomical Society. All rights reserved. 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) × 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-t0)/τ , where t 0 = 57631.0 (MJD) and τ ≃ 15 days. The X-ray shows a marginal detection at L X = 2.4 1.9 -1.1 × 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 ν L ν < 1.7 × 10 36 erg s -1 and ν L ν < 2.3 × 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. Themore » 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.« less

Authors:

Blagorodnova, N. ^[1]; Gezari, S.  ^[2];

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Hung, T.  ^[3];

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Kulkarni, S. R.  ^[1];

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Cenko, S. B.  ^[4];

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Pasham, D. R. ^[5]; Yan, L. ^[6]; Arcavi, I.  ^[7];

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Ben-Ami, S.  ^[8];

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Bue, B. D. ^[9]; Cantwell, T. ^[10]; Cao, Y. ^[11]; Castro-Tirado, A. J. ^[12]; Fender, R. ^[13]; Fremling, C.  ^[14];

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Gal-Yam, A. ^[15]; Ho, A. Y. Q. ^[1]; Horesh, A. ^[16]; Hosseinzadeh, G.  ^[7];

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Kasliwal, M. M.  ^[1]

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more »; Kong, A. K. H. ^[17]; Laher, R. R. ^[18]; Leloudas, G.  ^[19];

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Lunnan, R. ^[20]; Masci, F. J.  ^[18];

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Mooley, K.  ^[21];

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Neill, J. D. ^[1]; Nugent, P.  ^[22];

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Powell, M. ^[23]; Valeev, A. F. ^[24]; Vreeswijk, P. M. ^[15]; Walters, R. ^[1]; Wozniak, P. ^[25] « less

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+ Show Author Affiliations

1. California Inst. of Technology (CalTech), Pasadena, CA (United States). Cahill Center for Astrophysics
2. Univ. of Maryland, College Park, MD (United States). Dept. of Astronomy; Univ. of Maryland, College Park, MD (United States). Joint Space-Science Inst.
3. Univ. of Maryland, College Park, MD (United States). Dept. of Astronomy
4. Univ. of Maryland, College Park, MD (United States). Joint Space-Science Inst.; NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Center for Space Research
6. California Inst. of Technology (CalTech), Pasadena, CA (United States). Cahill Center for Astrophysics; California Inst. of Technology (CalTech), Pasadena, CA (United States). Infrared Processing and Analysis Center
7. Univ. of California, Santa Barbara, CA (United States). Dept. of Physics; Las Cumbres Observatory, Goleta, CA (United States)
8. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States). Smithsonian Astrophysical Observatory; Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics
9. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
10. Jodrell Bank Centre for Astrophysics, Manchester (United Kingdom)
11. Univ. of Washington, Seattle, WA (United States). Dept. of Astronomy
12. Instituto de Astrofisica de Andalucia (IAA-CSIC), Granada (Spain); Univ. de Malaga (Spain). Unidad Asociada Departamento de Ingeniera de Sistemas y Automtica
13. Univ. of Oxford, Oxford (United Kingdom). Dept. of Physics, Astrophysics
14. Stockholm Univ. (Sweden). Oskar Klein Center, Dept. of Astronomy
15. Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics
16. Hebrew Univ. of Jerusalem (Israel). Racah Inst. of Physics
17. Univ. of Oxford, Oxford (United Kingdom). Dept. of Physics, Astrophysics; National Tsing Hua Univ., Hsinchu (Taiwan). Inst. of Astronomy and Dept. of Physics
18. California Inst. of Technology (CalTech), Pasadena, CA (United States). Infrared Processing and Analysis Center
19. Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics; Univ. of Copenhagen (Denmark). The Niels Bohr Inst., Dark Cosmology Centre
20. California Inst. of Technology (CalTech), Pasadena, CA (United States). Cahill Center for Astrophysics; Stockholm Univ. (Sweden). Oskar Klein Center, Dept. of Astronomy
21. Univ. of Oxford, Oxford (United Kingdom). Dept. of Physics, Astrophysics
22. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Dept. of Astronomy
23. Yale Univ., New Haven, CT (United States). Dept. of Physics and Yale Center for Astronomy & Astrophysics
24. Special Astrophysical Observatory, Nizhnij Arkhyz, Karachai-Cherkessian Republic (Russia)
25. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Thu Jul 20 00:00:00 EDT 2017

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)

OSTI Identifier:

1412867

Alternate Identifier(s):

OSTI ID: 1418302

Report Number(s):

LA-UR-17-27712
Journal ID: ISSN 1538-4357; TRN: US1800382

Grant/Contract Number:  

AC52-06NA25396; AC02-05CH11231

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Volume: 844; Journal Issue: 1; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Astronomy and Astrophysics; accretion, accretion disks; black hole physics; galaxies nuclei; stars individual (iPTF16fnl)