Evidence for a Compact Wolf-Rayet Progenitor for the Type Ic Supernova PTF 10vgv

Abstract

We present the discovery of PTF 10vgv, a Type Ic supernova (SN) detected by the Palomar Transient Factory, using the Palomar 48 inch telescope (P48). R-band observations of the PTF 10vgv field with P48 probe the SN emission from its very early phases (about two weeks before R-band maximum) and set limits on its flux in the week prior to the discovery. Our sensitive upper limits and early detections constrain the post-shock-breakout luminosity of this event. Via comparison to numerical (analytical) models, we derive an upper-limit of R 4.5 R ☉ (R 1 R ☉) on the radius of the progenitor star, a direct indication in favor of a compact Wolf-Rayet star. Applying a similar analysis to the historical observations of SN 1994I yields R 1/4 R ☉ for the progenitor radius of this SN.

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arXiv:1110.5618v1 [astro-ph.CO] 25 Oct 2011
October 26, 2011
Evidence for a compact Wolf-Rayet progenitor for the Type Ic supernova
PTF10vgv
A. Corsi1, E. O. Ofek2, A. Gal-Yam2, D. A. Frail3, D. Poznanski4, P. A. Mazzali5,6,
S. R. Kulkarni7, M. M. Kasliwal7, I. Arcavi2, S. Ben-Ami2, S. B. Cenko8, A. V. Filippenko8,
D. B. Fox9, A. Horesh7, J. L. Howell9, I. K. W. Kleiser8, E. Nakar10, I. Rabinak2, R. Sari11,
J. M. Silverman8, D. Xu2, J. S. Bloom8, N. M. Law12, P. Nugent8,13, and R. M. Quimby7
ABSTRACT
We present the discovery of PTF10vgv, a Type Ic supernova detected by the Palo-
mar Transient Factory, using the Palomar 48-inch telescope (P48). R-band observa-
tions of the PTF10vgv field with P48 probe the supernova emission from its very
early phases (about two weeks before R-band maximum), and set limits on its flux in
1LIGO laboratory, California Institute of Technology, MS 100-36, Pasadena, CA 91125, USA; email:
corsi@caltech.edu
2Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot 76100, Israel
3National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801, USA
4School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
5INAF-Osservatorio Astronomico, vicolo dellOsservatorio, 5, I-35122 Padova, Italy
6Max-Planck Institut f¨ ur Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, Germany
7Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA, 91125, USA
8Department of Astronomy, University of California, Berkeley, CA 94720-3411,USA
9Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, Pennsylvania 16802,
USA
10Raymond and Beverly Sackler School of Physics & Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
11Racah Institute for Physics, The Hebrew University, Jerusalem 91904, Israel
12Dunlap Institute forAstronomyandAstrophysics,Universityof Toronto,50 St. GeorgeStreet, TorontoM5S 3H4,
Ontario, Canada
13Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA
94720, USA

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the week prior to the discovery. Our sensitive upper limits and early detections con-
strain the post-shock-breakout luminosity of this event. Via comparison to numerical
(analytical) models, we derive an upper-limit of R ? 4.5R⊙(R ? 1R⊙) on the radius of
the progenitor star, a direct indication in favor of a compact Wolf-Rayet star. Applying
a similar analysis to the historical observations of SN1994I, yields R ? 1/4R⊙for the
progenitor radius of this supernova.
Subject headings: supernovae: general — supernovae: individual (PTF10vgv)
1.Introduction
Core-collapse supernovae (SNe) are believed to originate from evolved, massive progenitors
(initial mass ? 8–10M⊙) whose iron core undergoes gravitational collapse. Among them, Type
II-Plateau (II-P) SNe show prominent hydrogen in their spectrum and a plateau in the optical light
curves. Type IIb SNe have hydrogen in the spectrum initially, and a H-deficient spectrum at later
times. Finally, Types Ib and Ic show no evidence for hydrogen at any time. The H-deficient/H-poor
core-collapse SNe are thought to be produced by progenitors stripped of their hydrogen (SN Ib)
and possibly helium (SN Ic) envelopes prior to exploding (for a review, see Filippenko 1997).
Due to the stiff dependence of mass loss on luminosity/mass, a sequence of increasing main-
sequence mass may be pictured going from progenitors of SNe II-P, IIb, Ib, and Ic (Heger et al.
2003; Crowther 2007; Georgy et al. 2009). Rotation, metallicity, and binarity also affect the mass
loss (e.g., Meynet et al. 1994; Meynet & Maeder 2000).
The viability of the standard explosion mechanism for stars of increasing mass is challenging,
given that their higher mass cores are more bound, and their SN shocks subject to a very high
accretion rate (e.g., Burrows et al. 2007). Binary-star evolution has been studied as a channel to
circumvent thiscaveat (e.g., Utrobin 1994; Woosley et al. 1994; Young et al. 1995; Blinnikov et al.
1998; Fryer et al. 2007; Yoon et al. 2010; Smith et al. 2011). The basic ingredient of this scenario
is mass loss through transfer onto a companion. In this case, the mass-loss luminosity scaling does
not apply, and much lower mass progenitors can explode as H-poor cores.
Recently, Dessart et al. (2011) published simulations of SN light curves resulting from explo-
sions of SN IIb/Ib/Ic progenitors. All SNe show a ∼ 10-day-long post-breakout plateau with a
luminosity of (1 − 5) × 107L⊙. Analytical estimates for the early-time (t ? 1 − 2d since explo-
sion) post-breakout emission have been provided by Rabinak & Waxman (2011) and Nakar & Sari
(2010).
In this paper we present the discovery of type Ic SN, PTF10vgv, detected by the Palomar

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TransientFactory1(PTF; Law et al.2009;Rau et al.2009)(§2). Wereportitsspectralclassification
(§3) and the radio follow-up observations (§4). We constrain the radius of the stellar progenitor of
this SN by comparing our tight pre-discovery upper-limits with the predictions of several models
(Dessart et al. 2011; Rabinak & Waxman 2011; Nakar & Sari 2010) (§5).
2. Discovery and R-band photometry
On 2010 September 14.1446 (UTC times are used throughout), we discovered a Type Ic SN,
PTF10vgv, via the automated Oarical software (Bloom et al. 2011). The SN was visible at a
magnitude of R ≈ 19.9 (Table 1 and Figure 1) in an image (60s exposure) taken with the Palomar
Oschin Schmidt 48-inch telescope(P48). It was not seen in previous images of thesame field taken
on 2010 September 12.4830, down to a limiting magnitude of R > 20.2. The SN J2000 position
is α = 22h16m01.17s, δ = +40◦52′03.3′′(Corsi et al. 2010a), at an angular distance of ∼ 5′′from
the galaxy SDSS2J221601.54+405206.5. P48 observations were obtained with the Mould-R filter
(Table1 and Figure2). A high-qualityimageproduced by stackingseveral imagesof thesamefield
wasusedasareference andsubtractedfromtheindividualimages. Photometrywasperformedwith
an aperture of 2′′radius relative to the r-band magnitudes of ten SDSS reference stars in the field
(Figure 1), applying color corrections (Corsi et al. 2011; Ofek et al. 2011). Aperture corrections
wereapplied toaccount forsystematicerrors as well aserrors introducedbythesubtractionprocess
(Corsi et al. 2011).
Table 1:: P48 observations of PTF10vgv in R-band.
Start timeExposure
(s)
600
60
60
60
60
60
360
60
60
Maga
[mag]
< 21.2b
< 20.8b
< 21.1b
< 20.9b
< 20.8b
< 20.6b
< 20.8b
< 20.6b
< 20.8b
JD-2455453.6446 (d)
-6.776
-6.776
-6.732
-5.732
-5.688
-3.811
-3.811
-3.766
-2.814
1http://www.astro.caltech.edu/ptf/
2Sloan Digital Sky Survey (York et al. 2000).

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-2.768
-1.706
-1.662
0.000
0.044
0.996
1.043
1.994
2.068
3.019
3.064
4.075
4.122
5.073
5.117
6.065
6.108
7.078
7.122
8.058
8.106
9.148
9.193
10.149
10.193
11.060
11.103
12.126
12.170
13.146
13.190
14.068
14.143
15.096
15.152
17.134
17.180
18.215
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
< 21.4b
< 20.4b
< 20.2b
19.897 ± 0.079
19.788 ± 0.081
18.489 ± 0.053
18.455 ± 0.037
17.742 ± 0.032
17.803 ± 0.035
17.283 ± 0.033
17.270 ± 0.034
16.904 ± 0.024
16.879 ± 0.023
16.676 ± 0.025
16.660 ± 0.034
16.496 ± 0.026
16.464 ± 0.046
16.360 ± 0.031
16.349 ± 0.025
16.297 ± 0.025
16.297 ± 0.030
16.224 ± 0.054
16.238 ± 0.049
16.230 ± 0.039
16.204 ± 0.050
16.222 ± 0.045
16.223 ± 0.042
16.224 ± 0.033
16.234 ± 0.027
16.267 ± 0.022
16.284 ± 0.020
16.324 ± 0.025
16.338 ± 0.034
16.391 ± 0.035
16.384 ± 0.11
16.507 ± 0.090
16.554 ± 0.028
16.707 ± 0.033

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18.979
19.023
19.974
20.053
24.035
24.078
25.050
25.095
26.050
26.096
27.060
27.109
28.068
28.133
29.195
29.239
31.015
31.059
32.047
32.092
33.055
33.106
43.949
43.992
44.950
44.993
45.949
45.991
48.023
48.191
53.122
53.215
60.096
60.139
61.952
61.996
62.952
62.997
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
16.777 ± 0.042
16.778 ± 0.035
16.864 ± 0.038
16.885 ± 0.041
17.321 ± 0.031
17.345 ± 0.026
17.427 ± 0.029
17.427 ± 0.029
17.529 ± 0.031
17.530 ± 0.036
17.519 ± 0.030
17.627 ± 0.032
17.717 ± 0.028
17.695 ± 0.034
17.678 ± 0.027
17.799 ± 0.028
17.901 ± 0.046
17.903 ± 0.030
17.946 ± 0.031
17.965 ± 0.046
18.231 ± 0.055
18.034 ± 0.053
18.563 ± 0.046
18.638 ± 0.036
18.649 ± 0.042
18.537 ± 0.031
18.680 ± 0.054
18.679 ± 0.055
18.796 ± 0.041
18.802 ± 0.051
18.906 ± 0.046
19.008 ± 0.060
19.140 ± 0.057
18.985 ± 0.051
19.268 ± 0.072
19.131 ± 0.043
19.301 ± 0.071
19.240 ± 0.064