J/ApJ/873/92 Opt. & UV evolution of the TDE iPTF15af (Blagorodnova+, 2019)
The broad absorption line tidal disruption event iPTF15af: optical and
ultraviolet evolution.
Blagorodnova N., Cenko S.B., Kulkarni S.R., Arcavi I., Bloom J.S.,
Duggan G., Filippenko A.V., Fremling C., Horesh A., Hosseinzadeh G.,
Karamehmetoglu E., Levan A., Masci F.J., Nugent P.E., Pasham D.R.,
Veilleux S., Walters R., Yan L., Zheng W.
<Astrophys. J., 873, 92 (2019)>
=2019ApJ...873...92B 2019ApJ...873...92B
ADC_Keywords: Photometry, UBVRI; Photometry, ultraviolet; Spectra, optical;
Spectra, ultraviolet
Keywords: accretion, accretion disks ; black hole physics ; galaxies: nuclei ;
stars: individual (iPTF15af)
Abstract:
We present multiwavelength observations of the tidal disruption event
(TDE) iPTF15af, discovered by the intermediate Palomar Transient
Factory survey at redshift z=0.07897. The optical and ultraviolet (UV)
light curves of the transient show a slow decay over 5 months, in
agreement with previous optically discovered TDEs. It also has a
comparable blackbody peak luminosity of Lpeak∼1.5x1044erg/s. The
inferred temperature from the optical and UV data shows a value of
(3-5)x104K. The transient is not detected in X-rays up to
LX<3x1042erg/s within the first 5 months after discovery. The
optical spectra exhibit two distinct broad emission lines in the HeII
region, and at later times also Hα emission. Additionally,
emission from [NIII] and [OIII] is detected, likely produced by the
Bowen fluorescence effect. UV spectra reveal broad emission and
absorption lines associated with high-ionization states of NV, CIV,
SiIV, and possibly PV. These features, analogous to those of broad
absorption line quasars (BAL QSOs), require an absorber with column
densities NH>1023cm-2. This optically thick gas would also
explain the nondetection in soft X-rays. The profile of the absorption
lines with the highest column density material at the largest velocity
is opposite that of BAL QSOs. We suggest that radiation pressure
generated by the TDE flare at early times could have provided the
initial acceleration mechanism for this gas. Spectral UV line
monitoring of future TDEs could test this proposal.
Description:
iPTF15af was discovered by the iPTF survey on UTC 2015 January 15.3
(MJD 57037.3).
The transient's host galaxy SDSS J084828.13+220333.4 is located inside
the footprint of the Sloan Digital Sky Survey (SDSS) DR12 (V/147). An
archival spectrum of the host was obtained on MJD 53379 as part of the
SDSS spectroscopic survey.
After its discovery, the transient was simultaneously monitored for 3
months in the R band with the Palomar 48-inch telescope (P48) and in
the gri bands with the Palomar 60-inch telescope (P60).
Simultaneously, we also obtained follow-up photometry in the BVgri
bands with Las Cumbres Observatory's 1m telescope in Texas.
Following the optical discovery of iPTF15af, we initiated follow-up
observations with the Ultra-Violet Optical Telescope (UVOT) on board
the Swift satellite. The data were obtained in three successive
campaigns in all six UVOT filters. See Table 2.
Optical spectra were obtained with the Low Resolution Imaging
Spectrometer (LRIS) on the Keck I 10m telescope in 2015 Jan 22,
Feb 20, Mar 23, May 16, Jun 13 and 2017 Nov 15 (resolution ∼7Å).
UV (1145-3145Å) spectroscopy of iPTF15af was obtained
(PI S. B. Cenko, proposal GO-13853) with the Space Telescope Imaging
Spectrometer (STIS) on the Hubble Space Telescope (HST) on UTC 2015
March 08.1 (MJD 57089.1), at 52 days after discovery. See Section 2.5.
We used the X-ray Telescope (XRT) on board the Swift satellite to
observe iPTF15af in the 0.3-10.0keV bandpass. See Section 2.6.
Radio follow-up observations of iPTF15af were carried out with the
Jansky Very Large Array (PI A. Horesh) on UTC 2015 January 31, at 15
days after discovery. The source was not detected in either the C
(6.1GHz), or K (22GHz) bands with an rms of 28 and 36uJy, respectively.
We retrieved archival mid-IR data prior to and after the event from
the WISE survey and the 2017 release of NEOWISE
(Mainzer+ 2014, J/ApJ/792/30). Although the NEOWISE light curve shows
small variations around the archival value of the source in the
allWISE catalog, none of them are more significant than 3σ.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
08 48 28.12 +22 03 33.5 iPTF15af = PTF 15af
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 142 64 Optical difference imaging and Swift UV aperture
photometry of iPTF15af in the AB magnitude system
table3.dat 55 7 *Log of ground-based (and HST/STIS) spectroscopic
observations of iPTF15af
sp/* . 7 Keck/LRIS and HST/STIS spectra in ASCII format
--------------------------------------------------------------------------------
Note on table3.dat: All observations were conducted with a combination of
grism 400/3400 and grating 400/8500, and a long 1"-wide slit,
providing a resolution of ∼7Å.
--------------------------------------------------------------------------------
See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/313 : Palomar Transient Factory (PTF) photometric catalog 1.0 (Ofek+, 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/ApJ/676/944 : GALEX & CFHTLS cand. tidal disruption events (Gezari+, 2008)
J/ApJ/679/962 : Quasars with strong nitrogen emission lines (Jiang+, 2008)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/692/758 : BAL QSOs in SDSS-DR5 (Gibson+, 2009)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJS/210/3 : SDSS bulge, disk & total stellar masses (Mendel+, 2014)
J/ApJS/219/8 : SFR for WISE + SDSS spectroscopic galaxies (Chang+, 2015)
J/A+A/593/A68 : PTF12os & iPTF13bvn spectra & light curves (Fremling+, 2016)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/MNRAS/455/2918 : Photom. & line luminosities for ASASSN-14li (Holoien+, 2016)
J/MNRAS/459/3939 : Type II supernova light curves (Valenti+, 2016)
J/ApJ/844/46 : Photom. of transient event iPTF16fnl (Blagorodnova+, 2017)
J/MNRAS/469/323 : SDSS quasars with PV broad absorption (Capellupo+, 2017)
J/ApJ/852/72 : Luminosity functions of TDFs (van Velzen, 2018)
http://wiserep.weizmann.ac.il/ : Weizmann Interactive Supernova Data Repository
(WISeREP) home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.1 d MJD [56664/57185.3] Modified Julian Date
9- 14 F6.1 d Phase [-373.3/148] Days since discovery; MJD 57037.3
16- 29 A14 --- Tel Telescope + Instrument information (1)
31 A1 --- l_UVW1mag Limit flag on UVW1mag
33- 37 F5.2 mag UVW1mag [19/20.8]? Uncorrected Swift/UVOT UVW1 band
(AB) magnitude
39- 42 F4.2 mag e_UVW1mag [0.08/0.3]? Uncertainty in UVW1mag
44- 48 F5.2 mag UVM2mag [19/20.5]? Uncorrected Swift/UVOT UVM2 band
(AB) magnitude
50- 53 F4.2 mag e_UVM2mag [0.06/0.15]? Uncertainty in UVM2mag
55- 59 F5.2 mag UVW2mag [18.8/20.5]? Uncorrected Swift/UVOT UVW2 band
(AB) magnitude
61- 64 F4.2 mag e_UVW2mag [0.05/0.16]? Uncertainty in UVW2mag
66 A1 --- l_Umag Limit flag on Umag
68- 72 F5.2 mag Umag [19/20]? Uncorrected Swift/UVOT U band (AB)
magnitude
74- 77 F4.2 mag e_Umag [0.1/0.3]? Uncertainty in Umag
79 A1 --- l_Bmag Limit flag on Bmag
81- 85 F5.2 mag Bmag [18.4/21]? Uncorrected Swift/UVOT B band (AB)
magnitude
87- 90 F4.2 mag e_Bmag [0.15/0.8]? Uncertainty in Bmag
92 A1 --- l_Vmag Limit flag on Vmag
94- 98 F5.2 mag Vmag [17.5/21.2]? Uncorrected Swift/UVOT V band (AB)
magnitude
100-103 F4.2 mag e_Vmag [0.15/0.6]? Uncertainty in Vmag
105 A1 --- l_gmag Limit flag on gmag
107-111 F5.2 mag gmag [18.4/21.1]? Uncorrected g band (AB) magnitude
113-116 F4.2 mag e_gmag [0.04/0.4]? Uncertainty in gmag
118 A1 --- l_rmag Limit flag on rmag
120-124 F5.2 mag rmag [18.5/23.3]? Uncorrected r band (AB)
magnitude (2)
126-129 F4.2 mag e_rmag [0.05/0.5]? Uncertainty in rmag
131 A1 --- l_imag Limit flag on imag
133-137 F5.2 mag imag [19.8/21.1]? Uncorrected i band (AB) magnitude
139-142 F4.2 mag e_imag [0.1/0.4]? Uncertainty in imag
--------------------------------------------------------------------------------
Note (1): Telescope and instrument as follows:
PTFP48 = Palomar 48-inch telescope.
P60+SEDM = Palomar 60-inch telescope with SED Machine spectrograph.
Las Cumbres 1m = Las Cumbres Observatory's 1m telescope in Texas.
Swift+UVOT = Ultra-Violet Optical Telescope on Swift.
Note (2): The rmag values are in the Mould-R filter system when the P48
telescope is used.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 d Phase [7/1035] Days since discovery; MJD 57037.3
7- 13 F7.1 d MJD [57044.5/58072.6] Modified Julian Date
of the observation
15- 33 A19 "datime" Date UTC date of observation
35- 44 A10 --- Tel Telescope + Instrument
46- 48 I3 deg PA [87/272]? Position angle
50- 53 I4 s Exp [600/2922] Exposure time
55 A1 --- f_MJD Flag on HST+STIS observation (1)
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Note (1): Flag as follows:
a = HST/STIS observation added in this table by CDS
from Section 2.5 and WISeREP data.
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Byte-by-byte Description of file (#): sp/* (except 2015-02-20 and HST)
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 11 F10.4 0.1nm lambda [3068.5/10339.4] Wavelength in Å
13- 24 E12.6 --- Flux [-1.2e-16/4.5e-16] Flux
26- 37 E12.6 --- Sky [-7e-17/4.3e-15]? Sky flux
40- 50 E11.6 --- e_Flux [3.5e-19/7.1e-17]? Flux uncertainty
53- 56 I4 pix Xpix [37/4094]? X pixel
64- 69 F6.3 pix Ypix [16.7/78.7]? Y pixel
72- 82 E11.6 --- R [1.7e+14/8.3e+16]? Response
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History:
From electronic version of the journal for Table 2.
Spectra downloaded from WISeREP at:
http://wiserep.weizmann.ac.il/object/5581
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Aug-2020