J/MNRAS/455/2918 Photometry & line luminosities for ASASSN-14li (Holoien+, 2016)
Six months of multiwavelength follow-up of the tidal disruption candidate
ASASSN-14li and implied TDE rates from ASAS-SN.
Holoien T.W.-S., Kochanek C.S., Prieto J.L., Stanek K.Z., Dong S.,
Shappee B.J., Grupe D., Brown J.S., Basu U., Beacom J.F., Bersier D.,
Brimacombe J., Danilet A.B., Falco E., Guo Z., Jose J., Herczeg G.J.,
Long F., Pojmanski G., Simonian G.V., Szczygiel D.M., Thompson T.A.,
Thorstensen J.R., Wagner R.M., Wozniak P.R.
<Mon. Not. R. Astron. Soc., 455, 2918-2935 (2016)>
=2016MNRAS.455.2918H 2016MNRAS.455.2918H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Black holes ; Photometry, ultraviolet ;
Photometry, ugriz ; X-ray sources
Keywords: accretion, accretion discs - black hole physics - galaxies: nuclei
Abstract:
We present ground-based and Swift photometric and spectroscopic
observations of the candidate tidal disruption event (TDE) ASASSN-14li,
found at the centre of PGC 043234 (d∼90 Mpc) by the All-Sky Automated
Survey for SuperNovae (ASAS-SN). The source had a peak bolometric
luminosity of L∼1044 erg/s and a total integrated energy of
E∼7x1050 erg radiated over the ∼6 months of observations presented.
The UV/optical emission of the source is well fitted by a blackbody with
roughly constant temperature of T∼35000 K, while the luminosity declines
by roughly a factor of 16 over this time. The optical/UV luminosity
decline is broadly consistent with an exponential decline,
L∝e-t/t0, with t0∼60 d. ASASSN-14li also exhibits soft X-ray
emission comparable in luminosity to the optical and UV emission but
declining at a slower rate, and the X-ray emission now dominates. Spectra
of the source show broad Balmer and helium lines in emission as well as
strong blue continuum emission at all epochs. We use the discoveries
of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN,
finding an average rate of r∼4.1x10-5/yr per galaxy with a 90 per cent
confidence interval of (2.2-17.0)x10-5/yr per galaxy. ASAS-SN found
roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is
much higher than that of other surveys.
Description:
Following the discovery of the transient, we requested and were granted
a series of 53 Swift XRT and UVOT target-of-opportunity (ToO) observations
between 2014 November 30 and 2015 May 14. The UVOT observations were
obtained in six filters: V (5468 Å), B (4392 Å), U (3465 Å),
UVW1 (2600 Å), UVM2 (2246 Å), and UVW2 (1928 Å) (Poole et al.
2008MNRAS.383..627P 2008MNRAS.383..627P). In addition to the Swift XRT and UVOT observations,
we also obtained ugriz images with the LT 2-m telescope and the LCOGT 1-m
telescopes at Siding Spring Observatory, McDonald Observatory, Sutherland,
and Cerro Tololo.
We obtained spectra of ASASSN-14li spanning 145 d between UT 2014
December 02 and UT 2015 April 14. The spectrographs used for these
observations, along with wavelength range and resolution in angstroms,
were: SNIFS mounted on the 2.2-m University of Hawaii telescope
(3200-10000 Å, R∼3 Å), the Dual Imaging Spectrograph (DIS) mounted
on the Apache Point Observatory 3.5-m telescope (range 3500-9800 Å,
R∼7 Å), the Multi-Object Double Spectrographs (MODS; Pogge et al.
2010SPIE.7735E..0AP) mounted on the dual 8.4-m Large Binocular Telescope
(LBT) on Mount Graham (3200-10000 Å, R∼3 Å), the Modular Spectrograph
(Modspec) mounted on the MDM Observatory Hiltner 2.4-m telescope
(4660-6730 Å, R∼4 Å), the Ohio State Multi-Object Spectrograph
(OSMOS; Martini et al. 2011PASP..123..187M 2011PASP..123..187M) mounted on the MDM Observatory
Hiltner 2.4-m telescope (4200-6800 Å, R∼4 Å), the Fast Spectrograph
(FAST; Fabricant et al. 1998PASP..110...79F 1998PASP..110...79F) mounted on the Fred L. Whipple
Observatory Tillinghast 1.5-m telescope (3700-9000 Å, R∼3 Å), and
the Inamori Magellan Areal Camera and Spectrograph (IMACS; Dressler et al.
2011PASP..123..288D 2011PASP..123..288D) mounted on the Las Campanas Observatory Magellan-Baade
6.5-m telescope (3650-9740 Å, R∼8 Å).
Objects:
------------------------------------------------------
RA (ICRS) DE Designation(s)
------------------------------------------------------
12 48 15.22 +17 46 26.5 ASASSN-14li = LEDA 43234
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 31 512 Photometric data of ASASSN-14li
tablea2.dat 27 48 Swift XRT photometry of ASASSN-14li
tablea4.dat 32 15 Line luminosities for ASASSN-14li
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See also:
J/ApJ/676/944 : GALEX and CFHTLS candidate tidal disruption events
(Gezari+, 2008)
J/ApJ/793/38 : Palomar Transient Factory photometric observations
(Arcavi+, 2014)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/ApJ/836/25 : Swift UVOT light curves of ASASSN-15lh (Margutti+, 2017)
J/ApJ/852/72 : Luminosity functions of tidal disruption flares
(van Velzen, 2018)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.3 d MJD [56989.463/57161.9] Modified Julian Date
11- 16 F6.3 mag mag [14.26/17.572] Magnitude in Filt (1)
18- 22 F5.3 mag e_mag [0.002/0.223] Uncertainty in mag (1)
24- 25 A2 --- Filt Filter
27- 31 A5 --- Tel Telescope (Swift, LT, LCOGT)
--------------------------------------------------------------------------------
Note (1): Magnitudes and uncertainties are presented in the natural system for
each filter: ugriz magnitudes are presented in the AB system, Swift filter
magnitudes are presented in the Vega system. Data are not corrected for
Galactic extinction.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.1 d MJD [56991.5/57156.7] Modified Julian Date
9- 12 F4.2 10-14W/m2 FX [1.05/2.6] The Swift XRT 0.3-10 keV X-ray
flux (in 10-11erg/s/cm2) (1)
14- 17 F4.2 10-14W/m2 e_FX [0.07/0.18] Uncertainty in FX
(in 10-11erg/s/cm2) (1)
19- 22 F4.2 ct/s CR [0.14/0.48] Count rate (1)
24- 27 F4.2 ct/s e_CR [0.01/0.02] Uncertainty in CR (1)
--------------------------------------------------------------------------------
Note (1): Data are not corrected for Galactic extinction.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d MJD [56993.5/57129.2] Modified Julian Date
10- 16 E7.3 10-7W LHa [1e+40/1.12e+41] Hα (6563 Å) luminosity
(in erg/s)
18- 24 E7.3 10-7W LHb [6.96e+39/5.63e+40]? Hβ (4861 Å) luminosity
(in erg/s)
26- 32 E7.3 10-7W LHeII [1e+40/8.67e+40] He II (4686 Å) luminosity
(in erg/s)
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 13-Dec-2018