J/ApJ/946/31 ZTF transient sources with HETDEX spectra (Vinko+, 2023)
Searching for supernovae in HETDEX Data Release 3.
Vinko J., Thomas B.P., Wheeler J.C., Ho A.Y.Q., Cooper E.M., Gebhardt K.,
Ciardullo R., Farrow D.J., Hill G.J., Jager Z., Kollatschny W., Liu C.,
Regos E., Sarneczky K.
<Astrophys. J., 946, 31 (2023)>
=2023ApJ...946...31V 2023ApJ...946...31V
ADC_Keywords: Spectra, optical; Redshifts; Supernovae; Active gal. nuclei;
Keywords: SNe ; Active galactic nuclei ; Spectroscopy
Abstract:
We have extracted 636 spectra taken at the positions of 583 transient
sources from the third data release of the Hobby-Eberly Telescope Dark
Energy eXperiment (HETDEX). The transients were discovered by the
Zwicky Transient Facility (ZTF) during 2018-2022. The HETDEX spectra
provide a potential means to obtain classifications for a large number
of objects found by photometric surveys for free. We attempt to
explore and classify the spectra by utilizing several
template-matching techniques. We have identified two transient
sources, ZTF20aatpoos = AT 2020fiz and ZTF19abdkelq, as supernova (SN)
candidates. We classify AT 2020fiz as a Type IIP SN observed ∼10d
after explosion, and we propose ZTF19abdkelq as a likely Type Ia SN
caught ∼40d after maximum light. ZTF photometry of these two sources
are consistent with their classifications as SNe. Beside these two
objects, we have confirmed several ZTF transients as variable active
galactic nuclei based on their spectral appearance, and determined the
host galaxy types of several other ZTF transients.
Description:
The Hobby-Eberly Telescope Dark Energy eXperiment (HETDEX; see
Gebhardt+ 2021ApJ...923..217G 2021ApJ...923..217G) uses the Visible Integral-field
Replicable Unit Spectrograph (VIRUS) instrument at the focal surface
of the HET. VIRUS comprises up to 78 IFUs, each with 448 1.5"-diameter
fibers, such that 33152 individual spectra covering 54arcmin2 are
obtained with each visit. The spectra extend from 3500 to 5500Å
with a resolution of ∼2Å.
The HETDEX Data Release 2.1 (HDR2.1) continuum-source catalog contains
spectra for ∼62k unique objects (Mentuch Cooper+ 2023, see J/ApJ/943/177).
In the HETDEX Data Release 3 (HDR3), the size of the continuum-source
catalog has been extended further, reaching ∼230k sources. In this
paper we use the more extensive HDR3 data set.
We aimed to extract spectra at the positions of public ZTF transients
announced between 2017 and early 2022 from the HETDEX spectroscopic
data set. See Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 148 636 ZTF transients classified via
χ2-minimization
tablea2.dat 31 49 Parameters of the AGN sample
tablea3.dat 48 21 Parameters of the host galaxies having ALeRCE
SN light curve classification
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See also:
J/PASP/110/863 : Stellar Spectral Flux Library: 1150-25000Å (Pickles 1998)
J/ApJ/659/122 : Improved distances to type Ia supernovae (Jha+, 2007)
J/MNRAS/394/2266 : SN 2005cs one-year photometry (Pastorello+, 2009)
J/ApJ/895/32 : Zwicky Transient Facility BTS. I. (Fremling+, 2020)
J/ApJ/920/122 : Candidate Lyα-emitting galaxies spectra (Davis+, 2021)
J/ApJ/911/108 : Stars of HETDEX. I. RVs & metal-poor stars (Hawkins+, 2021)
J/ApJ/916/11 : HETDEX [OIII] emitters. I. Low-z galaxies (Indahl+, 2021)
J/ApJ/943/177 : HETDEX Public Source Cat. (V3.2) (Mentuch Cooper+, 2023)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [ZTF]
4- 12 A9 --- ZTF ZTF transient name (YYaaaaaaa)
14- 32 F19.15 deg RAdeg [7/274] Right Ascension (J2000)
34- 55 F22.19 deg DEdeg [-1.1/66.1] Declination (J2000)
57- 63 F7.1 d MJD-1 [58242.2/59636.4] Modified Julian Date of ZTF
observation start
65- 71 F7.1 d MJD-2 [58272.2/59641.4] Modified Julian Date of ZTF
observation stop
73- 77 I5 d MJD [57834/59168] Modified Julian Date of HETDEX
observation
79- 86 A8 --- Type ALeRCe Type (1)
88- 97 F10.8 --- Prob [0.28/1]? ALeRCe probability
99- 112 A14 --- SType Harvard classes for stars, Hubble-classes for
galaxies
114- 122 F9.6 --- S/N [-1.2/53.3] Signal-to-noise parameter
124- 134 F11.6 --- chi2 [0.001/3604] Normalized χ2
136- 143 F8.6 --- zspec [0/0.4] Spectroscopic redshift
145- 148 A4 --- Class χ2 classification (2)
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Note (1): The Automatic Learning for the Rapid Classification of events
(ALeRCe; Forster+ 2021AJ....161..242F 2021AJ....161..242F) Type, including "bogus" as follows:
VS = Variable star (118 occurrences)
AGN = Active Galactic Nucleus (123 occurrences)
SN = Supernova (93 occurrences)
asteroid = asteroid (4 occurrences)
bogus = artifact (251 occurrences)
Note (2): Classification via χ2 minimization as follows:
agn = Active Galactic Nucleus (54 occurrences)
gx = galaxy spectrum (141 occurrences)
low = low S/N spectrum (240 occurrences)
star = stellar spectrum (200 occurrences)
unc = uncertain (1 occurrence)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [ZTF]
4- 12 A9 --- ZTF ZTF transient name (YYaaaaaaa)
14- 18 F5.2 --- S/N [2.5/32.2] Signal-to-noise parameter
20- 26 F7.4 --- chi2 [0.37/11.3] normalized χ2
28- 31 F4.2 --- zspec [0.13/2.3] Spectroscopic redshift
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Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [ZTF]
4- 12 A9 --- ZTF ZTF transient name (YYaaaaaaa)
14- 18 A5 --- SNType Supernova type
20- 24 F5.3 --- SNProb [0.29/0.6] Supernova probability
26- 28 A3 --- Host Host Hubble type
30- 34 F5.2 --- S/N [3.12/21.1] Signal-to-noise parameter
36- 42 F7.4 --- chi2 [0.26/13.02] normalized χ2
44- 48 F5.3 --- zspec [0.026/0.18] Spectroscopic redshift
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Feb-2025