J/ApJ/933/196 Photometry and spectroscopy of ASASSN-17jz (Holoien+, 2022)
Investigating the nature of the luminous ambiguous nuclear transient
ASASSN-17jz.
Holoien T.W.-S., Neustadt J.M.M., Vallely P.J., Auchettl K., Hinkle J.T.,
Romero-Canizales C., Shappee B.J., Kochanek C.S., Stanek K.Z., Chen P.,
Dong S., Prieto J.L., Thompson T.A., Brink T.G., Filippenko A.V.,
Zheng W., Bersier D., Bose S., Burgasser A.J., Channa S., de Jaeger T.,
Hestenes J., Im M., Jeffers B., Jun H.D., Lansbury G., Post R.S.,
Ross T.W., Stern D., Tang K., Tucker M.A., Valenti S., Yunus S.,
Zhang K.D.
<Astrophys. J., 933, 196 (2022)>
=2022ApJ...933..196H 2022ApJ...933..196H
ADC_Keywords: Spectra, ultraviolet ; Spectra, optical ; Photometry ;
Transient ; Active gal. nuclei ; Supernovae
Keywords: Galaxy accretion disks ; Accretion ; Active galactic nuclei ;
Tidal disruption ; Supernovae
Abstract:
We present observations of the extremely luminous but ambiguous
nuclear transient (ANT) ASASSN-17jz, spanning roughly 1200 days of the
object's evolution. ASASSN-17jz was discovered by the All-Sky
Automated Survey for Supernovae (ASAS-SN) in the galaxy
SDSSJ171955.84+414049.4 on UT 2017 July 27 at a redshift of z=0.1641.
The transient peaked at an absolute B-band magnitude of
MB,peak=-22.81, corresponding to a bolometric luminosity of
Lbol,peak=8.3x1044erg/s, and exhibited late-time ultraviolet
emission that was still ongoing in our latest observations.
Integrating the full light curve gives a total emitted energy of
Etot=(1.36±0.08)x1052erg, with (0.80±0.02)x1052erg of this
emitted within 200 days of peak light. This late-time ultraviolet
emission is accompanied by increasing X-ray emission that becomes
softer as it brightens. ASASSN-17jz exhibited a large number of
spectral emission lines most commonly seen in active galactic nuclei
(AGNs) with little evidence of evolution. It also showed transient
Balmer features, which became fainter and broader over time, and are
still being detected >1000 days after peak brightness. We consider
various physical scenarios for the origin of the transient, including
supernovae (SNe), tidal disruption events, AGN outbursts, and ANTs. We
find that the most likely explanation is that ASASSN-17jz was a SN IIn
occurring in or near the disk of an existing AGN, and that the
late-time emission is caused by the AGN transitioning to a more active
state.
Description:
Here we study the nuclear outburst ASASSN-17jz spanning from 88 days
prior to peak light through 1081 days after peak. ASASSN-17jz was
discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) on
UT 2017 July 27 in the galaxy SDSS J171955.84+414049.4, at a redshift
of z=0.1641.
We retrieved archival ugriz images of the host galaxy SDSS J171955
from the Sloan Digital Sky Survey (SDSS) Data Release 16 (DR16) and
JHKS images from the Two Micron All-Sky Survey (2MASS). We also
obtained near-UV (NUV) and far-UV (FUV) magnitudes from the Galaxy
Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS) catalog and
infrared W1 and W2 magnitudes from the Wide-field Infrared Survey
Explorer AllWISE catalog. We also checked archival survey data from
the Catalina Real-Time Transient Survey (CRTS; Drake+ 2009, J/ApJ/696/870)
to search for signs of previous variability from SDSS J171955. CRTS
obtained observations of the galaxy beginning on UT 2005 July 1,
roughly 12yr prior to our first detection of ASASSN-17jz in ASAS-SN
V-band data, and there is no evidence of prior flaring in these data.
See Section 2.1.
ASAS-SN monitors the visible sky nightly to find bright, nearby
transients using units of four 14 cm telescopes. Currently, ASAS-SN
consists of five units in Hawaii, Chile, Texas, and South Africa
hosted by the Las Cumbres Observatory global telescope network using
g-band filters, but at the time of the discovery of ASASSN-17jz, it
was composed of only single units in Chile and in Hawaii using V-band
filters. Roughly two months after ASASSN-17jz was discovered, our
Texas unit began survey operations, and also started to observe
ASASSN-17jz in the g-band. See Section 2.2.
The Asteroid Terrestrial-impact Last Alert System (ATLAS) is an
ongoing survey that uses fully robotic 0.5m telescopes located on the
summit of Haleakala and Mauna Loa Observatory in Hawaii. ATLAS uses
two broad filters for its survey operations: "cyan" (c), covering
420-650nm, and "orange" (o) covering 560-820nm. We present the stacked
o-band photometry and 3σ limits in Table 3. See Section 2.3.
During our initial follow-up campaign of ASASSN-17jz, we obtained 23
epochs of Swift TOO observations spanning from 1 day before peak light
through 212 days after peak. We later obtained one epoch of
observations on 2018 September 16, and two epochs on 2020 July 21 and
2020 July 22 to monitor the long-term UV and X-ray evolution of this
transient. UVOT observations were obtained in the V (5468Å), B
(4392Å), U (3465Å), UVW1 (2600Å), UVM2 (2246Å), and UVW2
(1928Å) filters (Poole et al. 2008) at most epochs, with later
epochs only using the UV and U filters, as the transient had faded in
the optical. See Section 2.4.
We obtained additional BVgri observations from the Las Cumbres
Observatory 1m telescopes located at McDonald Observatory, Texas, and
from the 24 inch Post Observatory robotic telescopes located in
Mayhill, New Mexico, and Sierra Remote Observatory in California. We
further obtained BVRI images from the 0.76m Katzman Automatic Imaging
Telescope (KAIT) and the 1m Anna L. Nickel telescope at Lick Observatory.
See Section 2.5.
The telescopes and instruments used to obtain follow-up optical
spectra included the Spectrograph for the Rapid Acquisition of
Transients (SPRAT) on the 2m Liverpool Telescope (LT), the Kast
Spectrograph on the 3m Shane telescope at Lick Observatory, the Double
Spectrograph (DBSP) on the 5.1m Hale telescope at Palomar Observatory,
the Multi-Object Double Spectrograph (MODS) on the dual 8.4m Large
Binocular Telescope (LBT), the Low-Resolution Imaging Spectrometer
(LRIS) on the Keck I 10m telescope, and the Deep Imaging Multi-Object
Spectrograph (DEIMOS) on the Keck II 10m telescope.
See Section 2.6, table A1 and Figure 2.
We also obtained 4 observations on 2017 September, October and
November using the Space Telescope Imaging Spectrograph (STIS) on the
Hubble Space Telescope (HST; GO-14781; PI: C. Kochanek). We used the
FUV/NUV MAMA detectors with the G140L (1150-1730Å, FUV-MAMA) and
G230L (1570-3180Å, NUV-MAMA) gratings and 52.0"x0.2" slit.
See Section 2.7 and Figure 3.
Finally, we obtained radio observations of ASASSN-17jz using
Director's Discretionary Time observations at 10GHz with the Karl G.
Jansky Very Large Array (VLA; legacy code AR981) in its BnA
configuration on 2018 February 23, and TOO observations at 5GHz with
the electronic European very long baseline interferometry Network
(e-EVN) on 2018 April 11 (project code RR011).
See Section 2.8.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
17 19 55.85 +41 40 49.4 ASASSN-17jz = AT 2017fro
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 34 683 Stacked host-subtracted photometry of ASASSN-17jz
fig2.dat 50 126131 Optical spectroscopic evolution of ASASSN-17jz
fig3.dat 38 16065 HST/STIS UV spectroscopic evolution of ASASSN-17jz
tablea1.dat 104 34 Optical spectroscopic Observation logs
of ASASSN-17jz
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VII/23 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
II/335 : Revised cat. of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
II/328 : AllWISE Data Release (Cutri+ 2013)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
J/AJ/124/3042 : Narrow-line Sy1 galaxies from SDSS EDR (Williams+, 2002)
J/ApJ/613/682 : AGN masses & broad-line region sizes (Peterson+, 2004)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJS/189/15 : FeII emission in a sample of AGN spectra (Kovacevic+, 2010)
J/ApJ/772/26 : AGN with WISE. II. The NDWFS Bootes field (Assef+, 2013)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/MNRAS/455/2918 : Phot. & line luminosities for ASASSN-14li (Holoien+, 2016)
J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)
J/ApJ/844/46 : Phot. of the transient event iPTF16fnl (Blagorodnova+, 2017)
J/ApJS/233/17 : Swift/BAT AGN spectroscopic survey. V. X-ray (Ricci+, 2017)
J/MNRAS/465/L114 : OGLE16aaa UVOT light curves (Wyrzykowski+, 2017)
J/ApJ/880/120 : Phot. of the tidal disruption event PS18kh (Holoien+, 2019)
J/ApJ/883/147 : LCs of the energetic H-stripped SN2016coi (Terreran+, 2019)
J/ApJ/872/198 : LCs of tidal disruption flare AT2018zr (van Velzen+, 2019)
J/ApJ/898/161 : 500days of ASASSN-18pg multiwavelength obs. (Holoien+, 2020)
J/ApJ/903/31 : Phot. AT 2018hyz with Swift XRT, UVOT & Swope (Hung+, 2020)
J/ApJ/930/12 : Phot. & sp. follow-up of ASASSN-20hx (Hinkle+, 2022)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d MJD1 [57876.48/59051.2] Modified Julian date
lower range (1)
10- 17 F8.2 d MJD2 [57887.6/59052.7]? Modified Julian date
upper range (1)
19- 22 A4 --- Filt Photometric filter
24 A1 --- l_mag The 3-sigma upper limit flag on mag
25- 29 F5.2 mag mag [16.54/20.76] Apparent AB magnitude in Filt,
corrected for Galactic extinction (2)
31- 34 F4.2 mag e_mag [0.01/0.6]? Uncertainty on mag
--------------------------------------------------------------------------------
Note (1): A range of MJDs indicates the MJD range of all observations combined
to obtain a single magnitude measurement.
Note (2): All magnitudes are in the AB system and have been corrected
for Galactic extinction. All BVRI, gri, and ATLAS c and o data have
been stacked in bins of 1 day, as described in the text.
Swift UV+U data are not stacked except for the final two epochs.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.6 d MJD [57965.9/59107.2] Modified Julian date of
observation
14- 19 A6 --- Inst Spectroscopic instrument (G1)
21- 30 A10 "Y/M/D" Date Observation date (UT)
31 A1 --- m_Date [ab] Multiple observation on Date
33- 39 F7.1 0.1nm lambda [2629.6/10218.5] Wavelength; Angstroms
41- 50 E10.3 cW/m2/nm Flux [-1.2e-14/2.35e-14] Flux (in erg/s/cm2/Å)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "Y/M/D" Date Observation date (UT) (1)
12- 20 F9.3 d MJD [58015.6/58061.8] Modified Julian date of
observation
22- 27 F6.1 0.1nm lambda [988/2714.3] Wavelength; Angstroms
29- 38 E10.3 cW/m2/nm Flux [-6.8e-15/1.98e-14] Flux (in erg/s/cm2/Å)
--------------------------------------------------------------------------------
Note (1): "20110059" date was a misprint for "2017 10 05"; corrected at CDS.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.6 --- MJD [57965.9/59107.2] Modified Julian date of
observation
14- 17 A4 yr Date.Y Year of observation (UT)
19- 21 A3 "month" Date.M Month of observation (UT)
23- 27 F5.2 d Date.D Day of observation in decimal days (UT)
29- 42 A14 --- Tel Telescope
44- 49 A6 --- Inst Instrument (G1)
51- 68 A18 --- Grating Grating
70- 72 F3.1 arcsec Slit [1/2] Slit
74- 104 A31 s Exp Exposure time
--------------------------------------------------------------------------------
Global notes:
Note (G1): Instrument as follows:
DBSP = the Double Spectrograph on the 5.1m Hale telescope at Palomar
Observatory (4 observations)
DEIMOS = the Deep Imaging Multi-Object Spectrograph on the Keck II 10m
telescope (2 observations)
Kast = the Kast Spectrograph on the 3m Shane telescope at Lick Observatory
(7 observations)
LRIS = the Low-Resolution Imaging Spectrometer on the Keck I 10m telescope
(3 observations)
MODS = the Multi-Object Double Spectrograph on the dual 8.4m Large Binocular
Telescope (4 observations)
SPRAT = the Spectrograph for the Rapid Acquisition of Transients on the 2m
Liverpool Telescope (14 observations)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Katia van der Woerd [CDS] 04-Oct-2024