J/ApJ/914/57 Follow-up Opt. and NIR obs. of the SNIa SN2015bp (Wyatt+, 2021)
Strong near-infrared carbon absorption in the transitional type Ia SN 2015bp.
Wyatt S.D., Sand D.J., Hsiao E.Y., Burns C.R., Valenti S., Bostroem K.A.,
Lundquist M., Galbany L., Lu J., Ashall C., Diamond T.R., Filippenko A.V.,
Graham M.L., Hoeflich P., Kirshner R.P., Krisciunas K., Marion G.H.,
Morrell N., Persson S.E., Phillips M.M., Stritzinger M.D., Suntzeff N.B.,
Taddia F.
<Astrophys. J., 914, 57 (2021)>
=2021ApJ...914...57W 2021ApJ...914...57W
ADC_Keywords: Supernovae; Photometry; Spectra, optical; Spectra, infrared
Keywords: Supernovae ; Observational astronomy ; White dwarf stars ;
Type Ia supernovae
Abstract:
Unburned carbon is potentially a powerful probe of Type Ia supernova
(SN) explosion mechanisms. We present comprehensive optical and
near-infrared (NIR) data on the "transitional" Type Ia SN 2015bp. An
early NIR spectrum (t=-9.9 days with respect to B-band maximum)
displays a striking CI 1.0693µm line at 11.9x103km/s, distinct
from the prominent Mg ii 1.0927 µm feature, which weakens toward
maximum light. SN 2015bp also displays a clear CII 6580Å notch
early (t=-10.9 days) at 13.2x103km/s, consistent with our NIR carbon
detection. At MB=-18.46, SN 2015bp is less luminous than a normal
SNIa and, along with iPTF 13ebh, is the second member of the
transitional subclass to display prominent early-time NIR carbon
absorption. We find it unlikely that the CI feature is misidentified
HeI 1.0830µm because this feature grows weaker toward maximum
light, while the helium line produced in some double-detonation models
grows stronger at these times. Intrigued by these strong NIR carbon
detections, but lacking NIR data for other SNe Ia, we investigated the
incidence of optical carbon in the sample of nine transitional SNe Ia
with early-time data (t≲-4 days). We find that four display
CII6580Å, while two others show tentative detections, in line with
the SN Ia population as a whole. We conclude that at least ∼50% of
transitional SNe Ia in our sample do not come from
sub-Chandrasekhar-mass explosions due to the clear presence of carbon
in their NIR and optical spectra.
Description:
SN 2015bp was discovered on 2015 March 16, 11:45:36 (JD=2457097.99)
by the Catalina Real-time Transient Survey (CRTS;
Drake+ 2009, J/ApJ/696/870).
Following discovery, observations were initiated by the Carnegie
Supernova Project II (CSP-II; Phillips+ 2019PASP..131a4001P 2019PASP..131a4001P and
Hsiao+ 2019, J/PASP/131/A4002), and optical photometric observations
began on 2015 March 19 using the Henrietta Swope 1m telescope at Las
Campanas Observatory in Chile. The Swope observations continued until
2015 August 15, obtaining 45 epochs in the CSP-II optical Johnson (BV)
and Sloan (ugri) filters. Once SN 2015bp had sufficiently faded in
March 2016, host-galaxy reference images were obtained for template
subtraction.
Retrocam on the du Pont 2.5m telescope located at Las Campanas
Observatory was also used to obtain 11 epochs of NIR photometric data
in the YJH filters starting on 2015-March-28 and ending on 2015-May-30.
See Section 2.1.
Optical spectroscopic observations began on 2013 March 20 and were
made with the low-resolution EFOSC2 spectrograph on the 3.6m New
Technology Telescope (NTT), the Wide-Field Reimaging CCD Camera
(WFCCD) on the du Pont 100 inch telescope, the Deep Imaging
Multi-Object Spectrograph (DEIMOS) on the Keck II 10m telescope, and
the Andalucia Faint Object Spectrograph and Camera (ALFOSC) on the
Nordic Optical Telescope (NOT). We also include some already published
spectra from Srivastav+ (2017MNRAS.466.2436S 2017MNRAS.466.2436S), which help fill in the
post-maximum evolution. The EFOSC2 data were taken as part of the
Public ESO Spectroscopic Survey of Transient Objects (PESSTO) project
(Smartt+ 2015, J/A+A/579/A40), and the reduced spectra were downloaded
directly from the ESO archive.
NIR spectroscopic observations began on 2015 March 21 using the Son of
ISAAC (SOFI) instrument on the NTT, the Folded-port Infrared
Echellette (FIRE) spectrograph on the Magellan Baade telescope, the
Gemini Near Infrared Spectrograph (GNIRS) on the Gemini North
Telescope, SpeX on the NASA Infrared Telescope Facility (IRTF), and
the Flamingos2 spectrograph (F2) on the Gemini South Telescope.
The SOFI data were taken during the PESSTO survey, and we downloaded
the reduced spectra directly from the ESO archive.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
15 05 30.07 +01 38 02.4 SN 2015bp = SNhunt 281
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 107 43 Optical photometry of SN 2015bp in
the natural Swope system
table3.dat 99 16 Journal of optical spectroscopic observations
table4.dat 92 13 Journal of NIR spectroscopic observations
spopt/* . 12 Individual optical spectra in CSV format
(from Figure 2)
spnir/* . 13 Individual NIR spectra in CSV format
(from Figure 3)
--------------------------------------------------------------------------------
See also:
B/eso : ESO Science Archive Catalog (ESO, 1991-2022)
II/183 : UBVRI Photometric Standards (Landolt 1992)
J/MNRAS/377/1531 : Optical & IR photometry of SN 2004eo (Pastorello+, 2007)
J/A+A/465/71 : 21cm observations of 452 galaxies (Theureau+, 2007)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/699/L139 : Spectral parameters of SNe Ia (Wang+, 2009)
J/AJ/139/519 : Carnegie supernova project. SNe Ia (Contreras+, 2010)
J/AJ/139/120 : Low-redshift Type-Ia supernovae (Folatelli+, 2010)
J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011)
J/ApJS/192/1 : Light-curve parameters from the SNLS (Conley+, 2011)
J/MNRAS/410/585 : SN 2009dc BVRI light curves (Silverman+, 2011)
J/AJ/143/126 : Spectroscopy of 462 nearby Type Ia SNe (Blondin+, 2012)
J/ApJ/745/74 : Pre-maximum spectra of type Ia SNe (Folatelli+, 2012)
J/MNRAS/425/1819 : Berkeley supernova Ia program. II. (Silverman+, 2012)
J/ApJ/746/85 : THe HST Cluster Supernova Survey. V. (Suzuki+, 2012)
J/ApJ/773/53 : Type Ia SNe spectroscopy by the CSP (Folatelli+, 2013)
J/A+A/554/A27 : 2011fe spectrophotometric time series (Pereira+, 2013)
J/MNRAS/444/3258 : Velocities and EW of PTF SNe Ia (Maguire+, 2014)
J/A+A/578/A9 : Optical and NIR spectra of SN iPTF13ebh (Hsiao+, 2015)
J/A+A/579/A40 : PESSTO catalog (Smartt+, 2015)
J/ApJ/869/56 : Updated calibration of the CSP-I SNIa sample (Burns+, 2018)
J/A+A/611/A58 : SN 2007on and SN 2011iv light curves (Gall+, 2018)
J/ApJ/874/150 : The first 3yrs of DES-SN (DES-SN3YR) (Brout+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 "Y/M/D" Date Date of observation (UT)
15- 22 F8.2 d MJD [57100.3/57249.1] Modified Julian Date
24- 29 F6.2 --- Phase [-11.38/137.31] Orbital phase
31- 36 F6.3 mag umag [13.88/18.8]? Sloan u-band magnitude
38- 42 F5.3 mag e_umag [0.005/0.03]? Uncertainty on the umag
44- 49 F6.3 mag Bmag [13.79/18.62] Johnson B magnitude
51- 55 F5.3 mag e_Bmag [0.005/0.02] Uncertainty on the Bmag
57- 62 F6.3 mag gmag [14.44/20.88] Sloan g-band magnitude
64- 68 F5.3 mag e_gmag [0.005/0.15] Uncertainty on the gmag
70- 75 F6.3 mag Vmag [13.78/18.57] Johnson V magnitude
77- 81 F5.3 mag e_Vmag [0.005/0.02] Uncertainty on the Vmag
83- 88 F6.3 mag rmag [13.73/19.25] Sloan r-band magnitude
90- 94 F5.3 mag e_rmag [0.005/0.03] Uncertainty on the rmag
96- 101 F6.3 mag imag [14.19/19.08] Sloan i-band magnitude
103- 107 F5.3 mag e_imag [0.005/0.04] Uncertainty on the imag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 "Y/M/D" Date Observation date (UT)
15- 21 F7.1 d MJD [57101.3/57281] Modified Julian Date
23- 28 A6 --- Inst Instrument (1)
30- 34 F5.1 d tmaxB [-10.9/168.8] Time relative to Bmax
(JD-2457112.71)
36- 39 F4.1 min tint [10/45]? Total integration time
41 A1 --- f_tint Flag on tint (2)
43- 99 A57 --- FileName Name of the CSV file in subdirectory "spopt"
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
EFOSC = the low-resolution EFOSC2 spectrograph on the 3.6m New
Technology Telescope (NTT; 5 occurrences)
ALFOSC = the Andalucia Faint Object Spectrograph and Camera on the Nordic
Optical Telescope (4 occurrences)
HFOSC = the Himalayan Faint Object Spectrograph Camera instrument mounted
on the 2-m Himalayan Chandra Telescope at the Indian Astronomical
Observatory (IAO) in Hanle, India
from Srivastav+ 2017MNRAS.466.2436S 2017MNRAS.466.2436S (4 occurrences)
WFCCD = the Wide-Field Reimaging CCD Camera on the du Pont 100 inch
telescope (2 occurrences)
DEIMOS = the Deep Imaging Multi-Object Spectrograph on the Keck II 10m
telescope (1 occurrence)
Note (2): Flag on tint:
c = Data from the HFOSC instrument were published in
Srivastav+ (2017MNRAS.466.2436S 2017MNRAS.466.2436S) and were acquired from
http://sne.space/
They did not include exposure times in their publication.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 "Y/M/D" Date Observation date (UT)
15- 21 F7.1 d MJD [57102.3/57174.2] Modified Julian Date
23- 28 A6 --- Inst Instrument (1)
30- 34 F5.1 d tmaxB [-9.9/62]? Time relative to Bmax
(JD-2457112.71)
36- 39 F4.1 min tint [8.4/50]? Total integration time
43- 92 A50 --- FileName Name of the CSV file in subdirectory "spnir"
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
FIRE = the Folded-port Infrared Echellette spectrograph on the Magellan
Baade telescope (4 occurrences)
GNRIS = the Gemini Near Infrared Spectrograph on the Gemini North
Telescope (3 occurrences)
IRTF = SpeX on the NASA Infrared Telescope Facility (2 occurrences)
SOFI = the Son OF ISAAC instrument on the NTT (2 occurrences)
F2 = the Flamingos2 spectrograph on the Gemini South Telescope
(1 occurrence)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Dec-2022