The Tidal Disruption Event AT 2018hyz II: Light Curve Modeling of a Partially Disrupted Star

Abstract

AT 2018hyz (=ASASSN-18zj) is a tidal disruption event (TDE) located in the nucleus of a quiescent E+A galaxy at a redshift of $z=0.04573$, first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN). We present optical+UV photometry of the transient, as well as an X-ray spectrum and radio upper limits. The bolometric light curve of AT 2018hyz is comparable to other known TDEs and declines at a rate consistent with a $t^{-5/3}$ at early times, emitting a total radiated energy of $E=9\times 10^{50}$ erg. An excess bump appears in the UV light curve about 50 days after bolometric peak, followed by a flattening beyond 250 days. The light curve shows an excess bump in the UV about 50 days after bolometric peak lasting for at least 100 days, which may be related to an outflow. We detect a constant X-ray source present for at least 86 days. The X-ray spectrum shows a total unabsorbed flux of $\sim 4\times 10^{-14}$ erg cm${}^{-2}$ s${}^{-1}$ and is best fit by a blackbody plus power-law model with a photon index of $\Gamma =0.8$. A thermal X-ray model is unable to account for photons $>1$ keV, while the radio non-detection favors inverse-Compton scattering rather than a jet for the non-thermal component. We model the optical and UV light curves using the Modular Open-Source Fitter for Transients (MOSFiT) and find a best fit for a black hole of $5.2\times 10^6$ M${}_{\odot }$ partially disrupting a $0.1$ M${}_{\odot }$ star (stripping a mass of $\sim 0.01$ M${}_{\odot }$ for the inferred impact parameter, $\beta =0.6$). The low optical depth implied by the small debris mass may explain how we are able to see hydrogen emission with disk-like line profiles in the spectra of AT 2018hyz (see our companion paper, Short et al.~2020).

arXiv comment10 pages, 10 figures, published in MNRAS

References in corpus (55)

• emcee: The MCMC Hammer
• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Gaia mission
• Star Formation in Galaxies Along the Hubble Sequence
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The Swift X-ray Telescope
• The Swift Ultra-Violet/Optical Telescope
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Revisiting the Scaling Relations of Black Hole Masses and Host Galaxy Properties
• Las Cumbres Observatory Global Telescope Network
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Deriving Physical Properties from Broadband Photometry with Prospector: Description of the Model and a Demonstration of its Accuracy Using 129 Galaxies in the Local Universe
• 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
• The Birth of a Relativistic Outflow in the Unusual γ-ray Transient Swift J164449.3+573451
• An Open Catalog for Supernova Data
• 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
• The Relationship of Hard X-ray and Optical Line Emission in Low Redshift Active Galactic Nuclei
• 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
• Weighing Black Holes using Tidal Disruption Events
• The Superluminous Transient ASASSN-15lh as a Tidal Disruption Event from a Kerr Black Hole
• Stellar velocity dispersions and emission line properties of SDSS-III/BOSS galaxies
• Luminous Thermal Flares from Quiescent Supermassive Black Holes
• MOSFiT: Modular Open-Source Fitter for Transients
• Tidal Disruption Events Prefer Unusual Host Galaxies
• Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li
• ASASSN-15lh: A Highly Super-Luminous Supernova
• The UV-bright, Slowly Declining Transient PS1-11af as a Partial Tidal Disruption Event
• A radio jet from the optical and x-ray bright stellar tidal disruption flare ASASSN-14li
• ASASSN-15oi: A Rapidly Evolving, Luminous Tidal Disruption Event at 216 Mpc
• The prompt-afterglow connection in Gamma-Ray Bursts: a comprehensive statistical analysis of Swift X-ray light-curves
• 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
• Late-time UV observations of tidal disruption flares reveal unobscured, compact accretion disks
• X-ray Brightening and UV Fading of Tidal Disruption Event ASASSN-15oi
• The spectral evolution of AT 2018dyb and the presence of metal lines in tidal disruption events
• The first tidal disruption flare in ZTF: from photometric selection to multi-wavelength characterization
• The Broad Absorption Line Tidal Disruption Event iPTF15af: Optical and Ultraviolet Evolution
• Three-Dimensional Simulations of Tidally Disrupted Solar-Type Stars and the Observational Signatures of Shock Breakout
• Simulating realistic disc formation in tidal disruption events
• A dependence of the tidal disruption event rate on global stellar surface mass density and stellar velocity dispersion
• Tidal disruptions of main sequence stars -- III. Stellar mass dependence of the character of partial disruptions
• The Tidal Disruption Event AT 2018hyz I: Double-peaked emission lines and a flat Balmer decrement
• The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow
• Constraints on off-axis jets from stellar tidal disruption flares
• The Long Term Evolution of ASASSN-14li
• Late Time Radio Emission from X-ray Selected Tidal Disruption Events

Cited by in corpus (32)

• Tidal Disruption Events
• Optical-Ultraviolet Tidal Disruption Events
• An outflow powers the optical rise of the nearby, fast-evolving tidal disruption event AT2019qiz
• The Tidal Disruption Event AT 2018hyz I: Double-peaked emission lines and a flat Balmer decrement
• Double-Peaked Balmer Emission Indicating Prompt Accretion Disk Formation in an X-Ray Faint Tidal Disruption Event
• Systematic light curve modelling of TDEs: statistical differences between the spectroscopic classes
• Fallback Rates from Partial Tidal Disruption Events
• The Host Galaxy and Rapidly Evolving Broad-line Region in the Changing-look Active Galactic Nucleus 1ES 1927+654
• An elliptical accretion disk following the tidal disruption event AT 2020zso
• Generalized equipartition method from an arbitrary viewing angle
• A Swift Fix for Nuclear Outbursts
• The Luminosity Function of Tidal Disruption Flares for the ZTF-I Survey
• Identifying Tidal Disruption Events with an Expansion of the FLEET Machine Learning Algorithm
• Light Curves of Partial Tidal Disruption Events
• Interaction of an outflow with surrounding gaseous clouds as the origin of the late-time radio flares in TDEs
• Elliptical accretion disk as a model for tidal disruption events
• Revisit the rate of tidal disruption events: the role of the partial tidal disruption event
• Discovery of late-time X-ray flare and anomalous emission line enhancement after the nuclear optical outburst in a narrow-line Seyfert 1 Galaxy
• The fast transient AT 2023clx in the nearby LINER galaxy NGC 3799 as a tidal disruption of a very low-mass star
• Scary Barbie: An Extremely Energetic, Long-Duration Tidal Disruption Event Candidate Without a Detected Host Galaxy at z = 0.995
• Fate of the remnant in tidal stripping event: repeating and non-repeating
• Exploring the origin of stars on bound and unbound orbits causing tidal disruption events
• Characterisation of the X-ray point source variability in the eROSITA south ecliptic pole field
• Partial Tidal Disruption Events by Intermediate-mass Black Holes in Supermassive and Intermediate-mass Black Hole Binaries
• Propagation of Precessing Jet in Envelope of Tidal Disruption Events
• MUSE IFU observations of galaxies hosting Tidal Disruption Events
• Accretion Flares from Stellar Collisions in Galactic Nuclei
• Revisiting the unification of tidal disruption events with polarimetry
• A detailed spectroscopic study of Tidal Disruption Events
• TUVO-21acq: a new cataclysmic variable discovered through a UV outburst
• Early results in the search for extreme coronal line emitters with the Dark Energy Spectroscopic Instrument
• A Mildly Relativistic Outflow Launched Two Years after Disruption in the Tidal Disruption Event AT2018hyz