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An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li

Cenko, S. Bradley and Cucchiara, Antonino and Roth, Nathaniel and Veilleux, Sylvain and Prochaska, J. Xavier and Yan, Lin and Guillochon, James and Maksym, W. Peter and Arcavi, Iair and Butler, Nathaniel R. and Filippenko, Alexei V. and Fruchter, Andrew S. and Gezari, Suvi and Kasen, Daniel and Levan, Andrew J. and Miller, Jon M. and Pasham, Dheeraj R. and Ramirez-Ruiz, Enrico and Strubbe, Linda E. and Tanvir, Nial R. and Tombesi, Francesco (2016) An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li. Astrophysical Journal Letters, 818 (2). Art. No. L32. ISSN 2041-8205. https://resolver.caltech.edu/CaltechAUTHORS:20160314-095808701

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Abstract

We present a Hubble Space Telescope Space Telescope Imaging Spectrograph spectrum of ASASSN-14li, the first rest-frame ultraviolet (UV) spectrum of a tidal disruption flare (TDF). The underlying continuum is well fit by a blackbody with T_(UV) = 3.5 x 10^4 K, an order of magnitude smaller than the temperature inferred from X-ray spectra (and significantly more precise than previous efforts based on optical and near-UV photometry). Superimposed on this blue continuum, we detect three classes of features: narrow absorption from the Milky Way (probably a high-velocity cloud), and narrow absorption and broad (~2000–8000 km s^(−1)) emission lines at or near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by Δv = −(250–400) km s^(−1). Due both to this velocity offset and the lack of common low-ionization features (Mg ii, Fe ii), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N iii], N iv], and He ii are quite prominent, while the common quasar emission lines of C iii] and Mg ii are weak or entirely absent. Detailed modeling of this spectrum will help elucidate fundamental questions regarding the nature of the emission processes at work in TDFs, while future UV spectroscopy of ASASSN-14li would help to confirm (or refute) the previously proposed connection between TDFs and "N-rich" quasars.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.3847/2041-8205/818/2/L32DOIArticle
http://iopscience.iop.org/article/10.3847/2041-8205/818/2/L32PublisherArticle
http://arxiv.org/abs/1601.03331arXivDiscussion Paper
ORCID:
AuthorORCID
Cenko, S. Bradley0000-0003-1673-970X
Veilleux, Sylvain0000-0002-3158-6820
Prochaska, J. Xavier0000-0002-7738-6875
Yan, Lin0000-0003-1710-9339
Arcavi, Iair0000-0001-7090-4898
Filippenko, Alexei V.0000-0003-3460-0103
Additional Information:© 2016 American Astronomical Society. Received 2016 January 12; accepted 2016 February 2; published 2016 February 18. We thank R. Chornock, M. Eracleous, P. Hall, and C. Kochanek for valuable discussions, and the HST staff for the prompt scheduling of these ToO observations. S.B.C. acknowledges the Aspen Center for Physics and NSF Grant #1066293 for hospitality. AVF's research was funded by NSF grant AST-1211916, the TABASGO Foundation, and the Christopher R. Redlich Fund. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Facility: HST (STIS) - .
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NSFPHY-1066293
NSFAST-1211916
TABASGO FoundationUNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
NASANAS 5-26555
Subject Keywords:accretion, accretion disks; stars: flare; ultraviolet: general
Issue or Number:2
Record Number:CaltechAUTHORS:20160314-095808701
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160314-095808701
Official Citation:S. Bradley Cenko et al 2016 ApJ 818 L32
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65332
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Mar 2016 19:17
Last Modified:03 Oct 2019 09:46

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