@misc{10481/65105,
year = {2020},
month = {11},
url = {http://hdl.handle.net/10481/65105},
abstract = {At 66 Mpc, AT2019qiz is the closest optical tidal disruption event (TDE) to date, with a luminosity intermediate between the
bulk of the population and the faint-and-fast event iPTF16fnl. Its proximity allowed a very early detection and triggering of
multiwavelength and spectroscopic follow-up well before maximum light. The velocity dispersion of the host galaxy and fits
to the TDE light curve indicate a black hole mass ≈106M , disrupting a star of ≈1M . By analysing our comprehensive UV,
optical, and X-ray data, we show that the early optical emission is dominated by an outflow, with a luminosity evolution L ∝ t2,
consistent with a photosphere expanding at constant velocity ( 2000 km s−1), and a line-forming region producing initially
blueshifted H and He II profiles with v = 3000–10 000 km s−1. The fastest optical ejecta approach the velocity inferred from
radio detections (modelled in a forthcoming companion paper from K. D. Alexander et al.), thus the same outflow may be
responsible for both the fast optical rise and the radio emission – the first time this connection has been observed in a TDE.
The light-curve rise begins 29 ± 2 d before maximum light, peaking when the photosphere reaches the radius where optical
photons can escape. The photosphere then undergoes a sudden transition, first cooling at constant radius then contracting at
constant temperature. At the same time, the blueshifts disappear from the spectrum and Bowen fluorescence lines (N III) become
prominent, implying a source of far-UV photons, while the X-ray light curve peaks at ≈1041 erg s−1. Assuming that these X-rays
are from prompt accretion, the size and mass of the outflow are consistent with the reprocessing layer needed to explain the
large optical to X-ray ratio in this and other optical TDEs, possibly favouring accretion-powered over collision-powered outflow
models.},
organization = {Royal Astronomical Society Research Fellowship},
organization = {European Research Council (ERC)

320360
647208},
organization = {European Commission

European Commission Joint Research Centre

730980},
organization = {Villum Fonden 	
19054},
organization = {Polish NCN MAESTRO Grant 	
2014/14/A/ST9/00121},
organization = {Polish NCN DAINA Grant 	
2017/27/L/ST9/03221},
organization = {Israel Science Foundation

2108/18
2752/19},
organization = {US-Israel Binational Science Foundation},
organization = {Israeli Council forHigher Education Alon Fellowship},
organization = {National Aeronautics & Space Administration (NASA)

80NSSC18K0577
NAS5-26555},
organization = {European Union (EU)

842471
839090},
organization = {European Union (EU)

PGC2018-095317-B-C21},
organization = {Portuguese Foundation for Science and Technology

CRISP PTDC/FIS-AST-31546
UIDB/00099/2020},
organization = {Australian Research Council

FT190100574},
organization = {CONICYT PFCHA/DOCTORADOBECAS CHILE 	
2017-72180113},
organization = {NASA through the NASA Hubble Fellowship grant - Space Telescope Science Institute 	
HST-HF2-51403.001-A},
organization = {European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under ESO programmes 	
1103.D-0328
0104.B-0709},
organization = {WilliamHerschel Telescope 	
W19B/P7},
organization = {Science & Technology Facilities Council (STFC)},
publisher = {Oxford Univ Press},
keywords = {Black hole physics},
keywords = {Galaxies: nuclei},
keywords = {Transients: tidal disruption events},
title = {An outflow powers the optical rise of the nearby, fast-evolving tidal disruption event AT2019qiz},
doi = {10.1093/mnras/staa2824},
author = {Nicholl, M. and Galbany González, Lluis},
}