J/ApJ/912/19 Follow-up phot. & sp. of 12 PGIR novae (De+, 2021)
A population of heavily reddened, optically missed novae from Palomar
Gattini-IR: constraints on the Galactic nova rate.
De K., Kasliwal M.M., Hankins M.J., Sokoloski J.L., Adams S.M.,
Ashley M.C.B., Babul A.-N., Bagdasaryan A., Delacroix A., Dekany R.,
Greffe T., Hale D., Jencson J.E., Karambelkar V.R., Lau R.M., Mahabal A.,
McKenna D., Moore A.M., Ofek E.O., Sharma M., Smith R.M., Soon J., Soria R.,
Srinivasaragavan G., Tinyanont S., Travouillon T., Tzanidakis A., Yao Y.
<Astrophys. J., 912, 19 (2021)>
=2021ApJ...912...19D 2021ApJ...912...19D
ADC_Keywords: Novae; Photometry, infrared; Surveys;
Spectra, optical; Spectra, infrared;
Keywords: Classical novae ; Novae ; Cataclysmic variable stars ;
White dwarf stars ; Interstellar dust extinction
Abstract:
The nova rate in the Milky Way remains largely uncertain, despite its
vital importance in constraining models of Galactic chemical evolution
as well as understanding progenitor channels for Type Ia supernovae.
The rate has been previously estimated to be in the range of
∼10-300yr-1, either based on extrapolations from a handful of very
bright optical novae or the nova rates in nearby galaxies; both
methods are subject to debatable assumptions. The total discovery rate
of optical novae remains much smaller (∼5-10/yr) than these estimates,
even with the advent of all-sky optical time-domain surveys. Here, we
present a systematic sample of 12 spectroscopically confirmed Galactic
novae detected in the first 17 months of Palomar Gattini-IR (PGIR), a
wide-field near-infrared time-domain survey. Operating in the J band
(∼1.2µm), which is significantly less affected by dust extinction
compared to optical bands, the extinction distribution of the PGIR
sample is highly skewed to a large extinction values (>50% of events
obscured by AV≳5mag). Using recent estimates for the distribution
of Galactic mass and dust, we show that the extinction distribution of
the PGIR sample is commensurate with dust models. The PGIR extinction
distribution is inconsistent with that reported in previous optical
searches (null-hypothesis probability <0.01%), suggesting that a large
population of highly obscured novae have been systematically missed in
previous optical searches. We perform the first quantitative
simulation of a 3π time-domain survey to estimate the Galactic nova
rate using PGIR, and derive a rate of ∼43.7-8.7+19.5yr-1. Our
results suggest that all-sky near-infrared time-domain surveys are
well poised to uncover the Galactic nova population.
Description:
In this paper, we present a sample of 12 spectroscopically confirmed
novae detected in the first 17 months -- between 2019 July 2 (the
start date of the survey when the reference image construction was
completed) and 2020 November 30 (the end of the 2020 Galactic bulge
season in the northern hemisphere) -- of the Palomar Gattini-IR (PGIR)
NIR time-domain survey (Moore & Kasliwal 2019NatAs...3..109M 2019NatAs...3..109M and
De+ 2020PASP..132b5001D 2020PASP..132b5001D). PGIR is a robotic, wide-field time-domain
survey at the Palomar Observatory using a 25deg2 J-band camera to
survey the entire northern visible sky (δ>-28.9°;
∼15000deg2) at a cadence of ∼2 nights.
In order to determine spectroscopic classifications of confirmed
novae, we obtained medium resolution optical and IR spectroscopic
follow-up (see Figure 3) using the Palomar 200 inch telescope (P200)
using the optical Double Spectrograph (DBSP) and NIR Triple
spectrograph (TSpec) at the Palomar Observatory, the NASA Infrared
Telescope Facility (IRTF) and Keck I telescopes at Maunakea, and the
Australian National University 2.3m telescope at Siding Spring
Observatory (SSO) using the Wide-field Spectrograph (WiFeS).
The IRTF data were acquired with the SpeX instrument in the SXD mode
(∼0.7-2.5um) as part of programs 2020A111 and 2020B087 (PI: K. De).
The Keck spectrum of PGIR 20ekz was acquired using the Low Resolution
Imaging Spectrometer (LRIS).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 172 12 *Summary of novae detected in the first 17 months
of the Palomar Gattini-IR (PGIR) survey
(see the Appendix section for details)
lcs/* . 12 Individual light curve in ASCII format
sp/* . 22 Individual spectrum in ASCII format
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Note on table1.dat: We caution that the light-curve parameters and
classifications are limited by the photometric coverage available for
each nova.
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See also:
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
J/AJ/99/1079 : Nova rate in NGC 5128 (Ciardullo+, 1990)
J/AJ/134/2340 : Membership of Praesepe & Coma Berenices (Kraus+, 2007)
J/ApJS/187/275 : Photometric histories of recurrent novae (Schaefer, 2010)
J/AJ/140/34 : Classification of nova light curves (Strope+, 2010)
J/ApJ/743/156 : NEOWISE obs. of NEOs: preliminary results (Mainzer+, 2011)
J/A+A/554/A123 : Near-IR catalog of novae in VVV survey area (Saito+, 2013)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJS/227/1 : HST survey for novae in M87. I. VI LCs (Shara+, 2016)
J/MNRAS/465/3039 : Eruptive variable protostars from VVV EW (Contreras+, 2017)
J/MNRAS/465/3011 : VVV high amplitude NIR var. stars (Contreras Pena+, 2017)
J/ApJ/834/196 : Galactic novae with m≤10 from 1900 to 2015 (Shafter, 2017)
J/ApJ/905/58 : The local universe. I. Ca-rich gap transients (De+, 2020)
J/ApJ/910/120 : Dwarf nova outbursts detected by ASAS-SN (Kawash+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [PGIR]
6- 10 A5 --- PGIR PGIR name
12- 20 A9 --- Name Name of the nova
22- 23 I2 h RAh Hour of right ascension (J2000)
25- 26 I2 min RAm Minute of right ascension (J2000)
28- 31 F4.1 s RAs Second of right ascension (J2000)
33 A1 --- DE- Sign of declination (J2000)
34- 35 I2 deg DEd Degree of declination (J2000)
37- 38 I2 arcmin DEm Arcminute of declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of declination (J2000)
45- 52 F8.2 d MJD [58685.2/59180.3] Modified Julian Date,
first detection (1)
54- 58 F5.2 mag Jmag [6.22/12.07] Peak J-band Vega magnitude (2)
60- 63 F4.2 mag e_Jmag [0.01/0.03] Uncertainty on the Jmag
65- 72 A8 --- phCl Photometric class of the nova based on
classification schemes of
Strope+ 2010, J/AJ/140/34
74- 82 A9 --- spCl Spectroscopic class of the nova based on
classification schemes of
Williams+ 1992AJ....104..725W 1992AJ....104..725W
84- 86 F3.1 --- phAv [1/9.4]? Estimated extinction toward the nova
using the photometric color, AV,c
88- 102 A15 --- spAv Estimated extinction toward the nova
using the spectroscopic method, AV,s (3)
104- 107 F4.1 --- Av [1.5/12.1] The total Galactic extinction along
this direction estimated in
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S)
109- 140 A32 --- File1 Name of the spectrum in ASCII format
in subdirectory "sp"
142- 172 A31 --- File2 Name of a second spectrum (if any)
in ASCII format in subdirectory "sp"
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Note (1): This column denotes the first detection of the nova in PGIR
difference images.
Note (2): The Peak Jmag denotes the brightest J magnitude in the nova light
curve (note that the PGIR survey may have missed the peak light curve
for some novae).
Note (3): For each spectroscopic reddening measurement, we indicate the
absorption feature used to estimate the reddening. We caution that the
high extinction inferred toward most events lie in a regime beyond the
well-calibrated range for these features.
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Byte-by-byte Description of file: lcs/*
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Bytes Format Units Label Explanations
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1- 10 F10.2 d JD Julian Date of observation
12 A1 --- l_Jmag 5 sigma upper limit
13- 17 F5.2 mag Jmag [6.2/14.8] PGIR J band magnitude
19- 24 F6.2 mag e_Jmag [0/0.21]?=-99 Uncertainty in Jmag
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 10 F10.4 0.1nm lambda [3081/25704] Wavelength
12- 23 E12.7 cW/m2/nm Flux [-1.8e+1/5e+4]?=- Flux
in erg/s/cm2/Å units
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Oct-2022