J/ApJ/923/167 SN 2018agk spectra and NIR-UV light curves (Wang+, 2021)
SN 2018agk: a prototypical type Ia supernova with a smooth power-law rise in
Kepler (K2).
Wang Q., Rest A., Zenati Y., Ridden-Harper R., Dimitriadis G., Narayan G.,
Villar V.A., Magee M.R., Foley R.J., Shaya E.J., Garnavich P., Wang L.,
Hu L., Bodi A., Armstrong P., Auchettl K., Barclay T., Barentsen G.,
Bognar Z., Brimacombe J., Bulger J., Burke J., Challis P., Chambers K.,
Coulter D.A., Csornyei G., Cseh B., Deckers M., Dotson J.L., Galbany L.,
Gonzalez-Gaitan S., Gromadzki M., Gully-Santiago M., Hanyecz O.,
Hedges C., Hiramatsu D., Hosseinzadeh G., Howell D.A., Howell S.B.,
Huber M.E., Jha S.W., Jones D.O., Konyves-Toth R., Kalup C.,
Kilpatrick C.D., Kriskovics L., Li W., Lowe T.B., Margheim S., McCully C.,
Mitra A., Munoz J.A., Nicholl M., Nordin J., Pal A., Pan Y.-C., Piro A.L.,
Rest S., Rino-Silvestre J., Rojas-Bravo C., Sarneczky K., Siebert M.R.,
Smartt S.J., Smith K., Sodor A., Stritzinger M.D., Szabo R., Szakats R.,
Tucker B.E., Vinko J., Wang X., Wheeler J.C., Young D.R., Zenteno A.,
Zhang K., Zsidi G.
<Astrophys. J., 923, 167 (2021)>
=2021ApJ...923..167W 2021ApJ...923..167W
ADC_Keywords: Supernovae; Spectra, optical; Spectra, ultraviolet;
Photometry, infrared
Keywords: Type Ia supernovae ; Supernovae ; Time domain astronomy
Abstract:
We present the 30 minutes cadence Kepler/K2 light curve of the Type Ia
supernova (SN Ia) SN 2018agk, covering approximately one week before
explosion, the full rise phase, and the decline until 40 days after
peak. We additionally present ground-based observations in multiple
bands within the same time range, including the 1 day cadence DECam
observations within the first ∼5 days after the first light. The
Kepler early light curve is fully consistent with a single power-law
rise, without evidence of any bump feature. We compare SN 2018agk with
a sample of other SNe Ia without early excess flux from the
literature. We find that SNe Ia without excess flux have slowly
evolving early colors in a narrow range (g-i~-0.20±0.20mag) within
the first ∼10 days. On the other hand, among SNe Ia detected with
excess, SN 2017cbv and SN 2018oh tend to be bluer, while iPTF16abc's
evolution is similar to normal SNe Ia without excess in g-i. We
further compare the Kepler light curve of SN 2018agk with companion-
interaction models, and rule out the existence of a typical
nondegenerate companion undergoing Roche lobe overflow at viewing
angles smaller than 45°.
Description:
The Type Ia SN 2018agk was discovered with the CTIO 4m Blanco DECam
camera on 2018-March-10 at 07:06:06 UTC (MJD 58188.296).
Throughout this paper, we use the Milky Way extinction of
E(B-V)MW=0.034 from the extinction map as described in
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S).
We obtained ground-based photometry with the CTIO 4m Blanco telescope
with DECam in g and i bands, the Swope 1.0m telescope at Las Campanas
Observatory in uBVgri bands, the 60/90cm Schmidt telescope on
Piszkesteto Mountain Station of Konkoly Observatory in BVRI bands, the
1.3m telescope at the Cerro Tololo Inter-American Observatory (CTIO)
in RIJHK bands, and the PS1 1.8m telescope at Haleakala on Maui,
Hawai'i in gri bands.
We also include photometric data from the Global Supernova Project
taken with Las Cumbres Observatory previously published in
Baltay+ (2021PASP..133d4002B 2021PASP..133d4002B).
IC 0855 was included as a Campaign 17 target through "The K2
ExtraGalactic Survey (KEGS) for Transients" (PI Rest) and the
"Multi-Observatory Monitoring of K2 Supernovae" (PI Foley) programs as
part of the K2 SCE (internal Kepler EPIC ID 228682548). We retrieved
the IC 0855 Kepler data through the Mikulski Archive for Space
Telescopes (MAST) after the end of K2 Campaign 17. See Section 2.2.
We obtained a total of 17 spectra for SN 2018agk from ground-based
observatories: one spectrum with the Gemini Multi-Object Spectrograph
(GMOS) on the Gemini-North telescope (GN-2018A-LP-13, PI: Garnavich);
four spectra with ESO Faint Object Spectrograph and Camera (EFOSC2) on
the ESO New Technology Telescope; one spectrum with the Kast
spectrograph (KAST) on the Lick Shane telescope (2018A-S023,
PI: Foley); two spectra with the Low-Resolution Imaging Spectrometer
(LRIS) on the Keck I telescope (U240, PI: Foley); one spectrum with
the Goodman High Throughput Spectrograph at the Southern Astrophysical
Research (SOAR) Telescope (2018A-0277, PI: Foley); five optical
spectra with the twin FLOYDS spectrographs mounted on Las Cumbres
Observatory's 2m Faulkes Telescopes North (FTN) at Haleakala
Observatory in Hawai'i and Faulkes Telescopes South (FTS) at Siding
Spring Observatory in Australia; and two spectra with the Low
Resolution Spectrograph-2 (LRS2) on the 10m Hobby-Eberly Telescope
(HET) at McDonald Observatory, where the UV and Orange arms of the
Blue Integral Field Unit were applied, resulting in a spectrum between
3640 and 6970Å. We additionally use the publicly available
classification spectrum, posted on the Transient Name Server (TNS),
obtained with the Wide-Field CCD (WFCCD) of the 2.5m du Pont
Telescope at Las Campanas Observatory. See Section 2.3.
We triggered Hubble Space Telescope (HST) follow-up of SN2018agk on
2018 March 16 (GO-15274, PI Garnavich). On the second visit, STIS CCD
spectra using the G430L and G750L gratings were obtained, providing
wavelength coverage from 170 to 1010nm. See Section 2.4.
This paper also uses data obtained with ANDICAM mounted to the 1.3m
telescope at the Cerro Tololo Inter-American Observatory (CTIO) and
operated by the SMARTS Consortium under program NOAO-18A-0047
(PI: Galbany).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
13 10 36.37 -04 29 08.6 SN 2018agk = SN 2018agk
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 126 21 Log of spectroscopic observations of SN 2018agk
table4.dat 114 157 Ground-based optical photometry of SN 2018agk
table5.dat 61 8 Ground-based infrared photometry of SN 2018agk
fig2.dat 60 3283 K2 light curve of SN 2018agk
sp/* . 19 *Individual spectra in ASCII format
(data behind Figures 3 and 7)
--------------------------------------------------------------------------------
Note on sp/* : The optical spectra are from various telescopes and
reduced through different pipelines (see Section 2.3 and 2.4 for
details), so the overall scale of spectral flux in individual spectrum
could be off within an order of magnitude. Nonetheless, in the
analysis only the normalized spectra have been used, and thus the
deviation in the overall scale does not influence our results.
--------------------------------------------------------------------------------
See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/ApJ/699/L139 : Spectral parameters of SNe Ia (Wang+, 2009)
J/ApJ/749/18 : Swift/UVOT observations of 12 nearby SN-Ia (Brown+, 2012)
J/AJ/143/126 : Spectroscopy of 462 nearby Type Ia supernovae (Blondin+, 2012)
J/A+A/554/A27 : 2011fe spectrophotometric time series (Pereira+, 2013)
J/MNRAS/438/L101 : First month on SN 2013ej (Valenti+, 2014)
J/ApJ/795/44 : PS1 SNe Ia (0.02<z<0.7) griz light curves (Rest+, 2014)
J/A+A/579/A40 : PESSTO catalog (Smartt+, 2015)
J/ApJ/826/56 : HST/WFC3 obs. of Cepheids in SN Ia host gal. (Riess+, 2016)
J/ApJ/859/101 : The supernovae Ia Pantheon sample (Scolnic+, 2018)
J/ApJ/870/13 : K2 LC alternative analysis of ASASSN-18bt (Shappee+, 2019)
J/ApJ/870/L1 : K2 obs. of type Ia supernova SN 2018oh (Dimitriadis+, 2019)
J/ApJ/876/85 : HST observations for LMC Cepheids (Riess+, 2019)
J/A+A/634/A37 : TURTLS Light curves of 56Ni distributions (Magee+, 2020)
J/ApJ/902/46 : LCO network light curves of SN Ia 2018gv (Yang+, 2020)
J/ApJ/902/47 : ZTF early obs. of type Ia SNe. II. Rise time (Miller+, 2020)
J/ApJ/902/48 : ZTF early obs. of type Ia supernovae. III. (Bulla+, 2020)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 --- MJD [58193.3/58310.3] Modified Julian Date
10- 15 F6.1 d Phase [-10.6/103.4] Phase (G1)
17- 28 A12 --- Tel Telescope
30- 36 A7 --- Inst Instrument
38- 43 A6 s Exp Exposure time(s)
45- 61 A17 --- Grism Grism / Grating
63- 66 I4 0.1nm Wave1 [1570/6000] Lower range of wavelength in Å
67 A1 --- --- [-]
68- 72 I5 0.1nm Wave2 [3180/10885] Upper range of wavelength in Å
74- 85 A12 --- Unit Flux density unit of the spectrum;
column added by CDS
87-126 A40 --- FileName Name of the ASCII file; column added by CDS
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d MJD [58185.5/58272.2] Modified Julian Date of
observation (JD-2400000.5)
10- 15 F6.2 d Phase [-18.18/66.25] Phase (G1)
17- 22 F6.3 mag Bmag [17/20.22]? B-band magnitude
24- 29 F6.3 mag Vmag [16.89/19.3]? V-band magnitude
31- 36 F6.3 mag Rmag [16.6/18]? R-band magnitude
38- 43 F6.3 mag Imag [16.7/18]? I-band magnitude
45- 50 F6.3 mag gmag [16.9/22.64]? g-band magnitude
52- 57 F6.3 mag rmag [16.7/24]? r-band magnitude
59- 64 F6.3 mag imag [17/22.6]? i-band magnitude
66- 70 F5.3 mag e_Bmag [0.008/0.12]? Uncertainty in Bmag
72- 76 F5.3 mag e_Vmag [0.009/0.08]? Uncertainty in Vmag
78- 82 F5.3 mag e_Rmag [0.04/0.12]? Uncertainty in Rmag
84- 88 F5.3 mag e_Imag [0.06/0.13]? Uncertainty in Imag
90- 94 F5.3 mag e_gmag [0.002/0.3]? Uncertainty in gmag
96-100 F5.3 mag e_rmag [0.007/2.6]? Uncertainty in rmag
102-106 F5.3 mag e_imag [0.002/5]? Uncertainty in imag
108-114 A7 --- Tel Telescope/Instrument used (1)
--------------------------------------------------------------------------------
Note (1): Telescope as follows:
LCO = Photometric data from the Global Supernova Project taken with
Las Cumbres Observatory previously published in
Baltay+ (2021PASP..133d4002B 2021PASP..133d4002B)
Swope = the Swope 1.0m telescope at Las Campanas Observatory
PS1 = the PS1 1.8m telescope at Haleakala on Maui, Hawai'i
Konkoly = the 60/90cm Schmidt telescope on Piszkesteto Mountain Station
of Konkoly Observatory
Decam = the CTIO 4m Blanco telescope with DECam
ANDICAM = ANDICAM mounted to the 1.3m telescope at the Cerro Tololo
Inter-American Observatory (CTIO)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d MJD [58204.2/58251.02] Modified Julian Date of
observation (JD-2400000.5)
10- 14 F5.2 d Phase [0.02/45.65] Phase (G1)
16- 21 F6.3 mag Hmag [17.2/18.1] H-band magnitude
23- 28 F6.3 mag Jmag [16.8/18.2] J-band magnitude
30- 35 F6.3 mag Kmag [16.3/17.6]? K-band magnitude
37- 41 F5.3 mag e_Hmag [0.06/0.3] Uncertainty in Hmag
43- 47 F5.3 mag e_Jmag [0.06/0.3] Uncertainty in Jmag
49- 53 F5.3 mag e_Kmag [0.06/0.2]? Uncertainty in Kmag
55- 61 A7 --- Inst Instrument used (SMARTS - "ANDICAM" or
NTT - "SOFI")
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.6 d MJD [3346.53/3413.6]? Time of K2 mid-observation,
MJD-50000
13- 24 F12.6 ct Net [8986.2/11678.4]? Net Counts
26- 37 F12.6 ct Raw [6894.4/12975.4]? Raw Counts
39- 50 F12.6 ct Sky [0/12472] Sky Counts
52- 60 F9.6 ct e_Net [14.6/17]? Error in Net counts
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 E24.18 0.1nm lambda [1586.3/10495.2] Wavelength in Angstroms
26- 50 E25.18 --- Flux Flux density (1)
52- 76 E25.18 --- e_Flux ? Uncertainty in Flux
--------------------------------------------------------------------------------
Note (1): Flux in various units (see Table 3).
--------------------------------------------------------------------------------
Note (G1): Phases relative to B-band maximum on MJD 58204.178 according
to SALT2 fit.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-May-2023