Optical follow-up of the tidal disruption event iPTF16fnl: new insights from X-shooter observations

Abstract

We present the results from Nordic Optical Telescope and X-shooter follow-up campaigns of the tidal disruption event (TDE) iPTF16fnl, covering the first $\sim$100 days after the transient discovery. We followed the source photometrically until the TDE emission was no longer detected above the host galaxy light. The bolometric luminosity evolution of the TDE is consistent with an exponential decay with e-folding constant t${}_0$=17.6$\pm$0.2 days. The early time spectra of the transient are dominated by broad He II $\lambda$4686, H$\beta$, H$\alpha$ and N III $\lambda$4100 emission lines. The latter is known to be produced together with the N III $\lambda$4640 in the Bowen fluorescence mechanism. Thanks to the medium resolution X-shooter spectra we have been able to separate the Bowen blend contribution from the broad He II emission line. The detection of the Bowen fluorescence lines in iPTF16fnl place this transient among the N-rich TDE subset. In the late-time X-shooter spectra, narrow emission lines of [O III] and [N II] originating from the host galaxy are detected, suggesting that the host galaxy harbours a weak AGN in its core. The properties of all broad emission lines evolve with time. The equivalent widths follow an exponential decay compatible with the bolometric luminosity evolution. The full-width a half maximum of the broad lines decline with time and the line profiles develop a narrow core at later epochs. Overall, the optical emission of iPTF16fnl can be explained by being produced in an optically thick region in which high densities favour the Bowen fluorescence mechanism and where multiple electron scatterings are responsible for the line broadening.

arXiv comment20 pages, 15 figures. Accepted for publication in MNRAS

References in corpus (63)

• The Sloan Digital Sky Survey: Technical Summary
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Host Galaxies of AGN
• Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood
• The Host Galaxies and Classification of Active Galactic Nuclei
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• A method for optimal image subtraction
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• The Palomar Transient Factory: System Overview, Performance and First Results
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• Automated data reduction workflows for astronomy
• Optical Flares from the Tidal Disruption of Stars by Massive Black Holes
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• An ultraviolet-optical flare from the tidal disruption of a helium-rich stellar core
• A Continuum of H- to He-Rich Tidal Disruption Candidates With a Preference for E+A Galaxies
• Stellar disruption by a supermassive black hole: is the light curve really proportional to $t^{-5/3}$?
• A unified model for tidal disruption events
• Optical discovery of probable stellar tidal disruption flares
• Multiband lightcurves of tidal disruption events
• Six Months of Multi-Wavelength Follow-up of the Tidal Disruption Candidate ASASSN-14li and Implied TDE Rates from ASAS-SN
• General Relativistic Hydrodynamic Simulation of Accretion Flow from a Stellar Tidal Disruption
• PS1-10jh: The Disruption of a Main-Sequence Star of Near-Solar Composition
• A Bright Year for Tidal Disruptions?
• The magnetar model for Type I superluminous supernovae I: Bayesian analysis of the full multicolour light curve sample with MOSFiT
• ASASSN-14ae: A Tidal Disruption Event at 200 Mpc
• New physical insights about Tidal Disruption Events from a comprehensive observational inventory at X-ray wavelengths
• The Superluminous Transient ASASSN-15lh as a Tidal Disruption Event from a Kerr Black Hole
• Tidal Disruption Events Prefer Unusual Host Galaxies
• The X-ray through Optical Fluxes and Line Strengths of Tidal Disruption Events
• Flows of X-ray gas reveal the disruption of a star by a massive black hole
• ASASSN-15lh: A Highly Super-Luminous Supernova
• The UV-bright, Slowly Declining Transient PS1-11af as a Partial Tidal Disruption Event
• PS16dtm: A Tidal Disruption Event in a Narrow-line Seyfert 1 Galaxy
• ASASSN-15oi: A Rapidly Evolving, Luminous Tidal Disruption Event at 216 Mpc
• A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger
• Evolution of tidal disruption candidates discovered by XMM-Newton
• A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes
• Revisiting optical tidal disruption events with iPTF16axa
• Black hole masses of tidal disruption event host galaxies
• iPTF16fnl: a faint and fast tidal disruption event in an E+A galaxy
• Evidence for rapid disk formation and reprocessing in the X-ray bright tidal disruption event AT 2018fyk
• A tidal disruption-like X-ray flare from the quiescent galaxy SDSS J120136.02+300305.5
• Late-time UV observations of tidal disruption flares reveal unobscured, compact accretion disks
• Candidate tidal disruption events from the XMM-Newton Slew Survey
• The Broad Absorption Line Tidal Disruption Event iPTF15af: Optical and Ultraviolet Evolution
• A new class of flares from accreting supermassive black holes
• Black hole masses of tidal disruption event host galaxies II
• Long-term stream evolution in tidal disruption events
• What Sets the Line Profiles in Tidal Disruption Events?
• An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li
• The Ultraviolet Spectroscopic Evolution of the Low-Luminosity Tidal Disruption Event iPTF16fnl
• The Post-Starburst Evolution of Tidal Disruption Event Host Galaxies
• OGLE16aaa - a Signature of a Hungry Super Massive Black Hole
• The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh
• PS1-10jh Continues to Follow the Fallback Accretion Rate of a Tidally Disrupted Star
• Discovery and Follow-up of the Unusual Nuclear Transient OGLE17aaj
• Far-UV HST Spectroscopy of An Unusual Hydrogen Poor Superluminous Supernova: SN2017egm
• ASASSN-15lh: A Superluminous Ultraviolet Rebrightening Observed by Swift and Hubble
• The He II Fowler lines and the O III and N III Bowen fluorescence lines in the symbiotic nova RR Tel
• Gaia transients in galactic nuclei

Cited by in corpus (27)

• Optical-Ultraviolet Tidal Disruption Events
• An outflow powers the optical rise of the nearby, fast-evolving tidal disruption event AT2019qiz
• The spectral evolution of AT 2018dyb and the presence of metal lines in tidal disruption events
• The Tidal Disruption Event AT 2018hyz I: Double-peaked emission lines and a flat Balmer decrement
• Transient Double-beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU
• Systematic light curve modelling of TDEs: statistical differences between the spectroscopic classes
• Distinguishing Tidal Disruption Events from Impostors
• Rapid late-time X-ray brightening of the tidal disruption event OGLE16aaa
• Accretion disc cooling and narrow absorption lines in the tidal disruption event AT 2019dsg
• The Lunar Gravitational-wave Antenna: Mission Studies and Science Case
• The nuclear transient AT 2017gge: a tidal disruption event in a dusty and gas-rich environment and the awakening of a dormant SMBH
• AT 2020wey and the class of faint and fast Tidal Disruption Events
• The rise and fall of the iron-strong nuclear transient PS16dtm
• Evidence for the preferential disruption of moderately massive stars by supermassive black holes
• Lightcurve Evolution of the nearest Tidal Disruption Event: A late-time, radio-only flare
• Measuring black hole masses from tidal disruption events and testing the $M_{\mathrm{BH}}-{\sigma }_{\ast }$ relation
• Extreme variability in an active galactic nucleus: Gaia16aax
• A possible tidal disruption event candidate in the black hole binary system of OJ 287
• AT 2023clx: the Faintest and Closest Optical Tidal Disruption Event Discovered in Nearby Star-forming Galaxy NGC 3799
• Light-Curve Structure and Halpha Line Formation in the Tidal Disruption Event AT 2019azh
• A light echo from the warm outflow in the ULIRG F01004-2237 following a major flare in its optical continuum emission
• Spectroscopic monitoring of the candidate tidal disruption event in F01004-2237
• The Effect of Impact Parameter on Tidal Disruption Events
• A new Bowen Fluorescence Flare and Extreme Coronal Line Emitter discovered by SRG/eROSITA
• A detailed spectroscopic study of Tidal Disruption Events
• IGR J12580+0134: The Nearest Tidal Disruption Event and its Faint Resurrection
• Signatures of anti-social mass-loss in the ordinary Type II SN 2024bch -- A non-interacting supernova with early high-ionisation features