2016/01/31 by S. Bradley Cenko, S. B. Cenko, Antonino Cucchiara +28 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Flare #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #Optics #Physics #Spectrum (functional analysis) #Ultraviolet #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.3847/2041-8205/818/2/l32
Accepted for publication in ApJ Letters. 8 pages, 4 figures
arxiv created 2016/02/02 · openalex publication_date 2016/02/18 · arxiv updated 2016/03/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 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 Δ v = −(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.