PTF 10bzf (SN 2010ah): a broad-line Ic supernova discovered by the Palomar Transient Factory

TLDR: In this article, a broad-line Type Ic supernova (SN), PTF 10bzf (SN 2010ah), was detected by the Palomar Transient Factory (PTF) on 2010 February 23.

Abstract: We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf (SN 2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SN distance is ≅218 Mpc, greater than GRB 980425/SN 1998bw and GRB 060218/SN 2006aj, but smaller than the other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we compare the properties of PTF 10bzf with those of SN 1998bw and other broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of ^(56)Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or radio counterpart to PTF 10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB 030329 or GRB 031203. Early-time radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB 030329 and GRB 031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf, we find that no GRB in the interplanetary network catalog could be associated with this SN.

Figures

Table 2 PTF 10bzf Follow-up Campaign

Figure 1. P48 discovery image of PTF 10bzf in the R band. For clarity purposes, a circle of 5′′ radius marks the position of the 10 reference stars used for P48 photometry calibration (1–10), and of the four reference stars used for calibration of the Wise data (W1–W4). The stars labeled as P1–P3 were used for the calibration of P60 photometry. The position of PTF 10bzf and its host galaxy are enclosed by a black ellipse. The inset shows in more detail PTF 10bzf inside its host. The SN is located at R.A. = 11:44:02.99 and decl. = +55:41:27.6 (J2000).

Figure 3. Gemini (black) spectrum of PTF 10bzf obtained on 2010 March 2, around the time of the R-band maximum. The spectrum is compared with that of SN 1997ef (green), SN 1998bw (red), and SN 2002ap (blue) at similar epochs. The SNe are ordered by peak luminosity. This ordering reveals a sequence also in line velocity and blending. The spectrum of SN 1998bw is the most affected by line broadening, as seen, for example, in the almost complete absence of the re-emission peak near 4500 Å and by the complete blending of the O i 7773 and the Ca ii IR triplet. PTF 10bzf is intermediate between SN 1998bw and the two non-GRB SNe 1997ef and 2002ap in both of these respects. Spectral data were retrieved from Mazzali et al. (2000) for SN 19997ef, Patat et al. (2001) for SN 1998bw, and Mazzali et al. (2002) for SN 2002ap. Main telluric lines have been removed from the PTF 10bzf spectrum.

Figure 2. Light curve of PTF 10bzf corrected for Galactic extinction. Absolute magnitudes are plotted on the right axis. P48 data in Mould-R filter (filled circles) and P60 data in r-band (open circles) are calibrated using r-band magnitudes of SDSS stars, and expressed in the AB system. For P48, we also include color term corrections estimated considering the r− i SDSS colors of the reference stars. Synthetic photometry obtained from Gemini (filled square) and Keck (filled triangle) spectra is referred to SDSS r-band and expressed in the AB system. From the Gemini spectrum, we estimate R − r ≈ −0.1 mag for the conversion from SDSS r-band magnitudes in the AB system to R-band magnitudes in the Vega system. Wise data in the R filter and Vega system (stars) are calibrated to SDSS as described in Jordi et al. (2006). For comparison with P48 photometry, Wise data are shifted to account for r − R ≈ 0.3 mag for the conversion from SDSS r-band magnitudes in the AB system, to Wise R-band magnitudes in the Vega system (Jordi et al. 2006). We also plot the R-band light-curve template of SN 1998bw (solid line), SN 2003jd (dotted line), SN 2009bb (dashed line), and SN 2002ap (dash-dotted line), rescaled to the redshift of PTF 10bzf. These templates are obtained by interpolating data retrieved from Galama et al. (1998) for SN 1998bw, Gal-Yam et al. (2002), Foley et al. (2003) for SN 2002ap, Valenti et al. (2008) for SN 2003jd, and Pignata et al. (2011) for SN 2009bb.

Table 1 Summary of Light-curve Properties

Figure 4. Keck (black) spectrum of PTF 10bzf obtained on 2010 March 7, about 5 days post R-band maximum. The spectrum is compared with that of SN 1997ef (green), SN 1998bw (red), and SN 2002ap (blue) at similar epochs. The SNe are ordered by peak luminosity. This ordering reveals a sequence also in line velocity and blending. The spectrum of SN 1998bw is the most affected by line broadening, as seen, for example, in the almost complete absence of the re-emission peak near 4500 Å and by the complete blending of the O i 7773 and the Ca ii IR triplet. PTF 10bzf is intermediate between SN 1998bw and the two non-GRB SNe 1997ef and 2002ap in both of these respects. Spectral data were retrieved from Mazzali et al. (2000) for SN 19997ef, Patat et al. (2001) for SN 1998bw, and Mazzali et al. (2002) for SN 2002ap. Main telluric lines have been removed from the PTF 10bzf spectrum.

Full text

The Astrophysical Journal, 741:76 (13pp), 2011 November 10 doi:10.1088/0004-637X/741/2/76
C

2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A.
PTF 10bzf (SN 2010ah): A BROAD-LINE Ic SUPERNOVA DISCOVERED
BY THE PALOMAR TRANSIENT FACTORY
A. Corsi
1
,E.O.Ofek
2,22
, D. A. Frail
3
, D. Poznanski
4,5,22
, I. Arcavi
6
,A.Gal-Yam
6
, S. R. Kulkarni
2
, K. Hurley
7
,
P. A. Mazzali
8,9
, D. A. Howell
10,11
,M.M.Kasliwal
2
, Y. Green
6
, D. Murray
10,11
, M. Sullivan
12
,D.Xu
6
,S.Ben-ami
6
,
J. S. Bloom
5
,S.B.Cenko
5
,N.M.Law
13
, P. Nugent
4,5
,R.M.Quimby
2
, V. Pal’shin
14
, J. Cummings
15
, V. Connaughton
16
,
K. Yamaoka
17
,A.Rau
18
, W. Boynton
19
, I. Mitrofanov
20
, and J. Goldsten
21
1
LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, CA 91125, USA; corsi@caltech.edu
2
Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
3
National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801, USA
4
Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
5
Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720-3411, USA
6
Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot 76100, Israel
7
Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA
8
INAF-Osservatorio Astronomico, vicolo dell’Osservatorio 5, I-35122 Padova, Italy
9
Max-Planck Institut f
¨
ur Astrophysik, Karl-Schwarzschildstr. 1, D-85748 Garching, Germany
10
Las Cumbres Observatory Global Telescope Network, Inc., Santa Barbara, CA 93117, USA
11
Department of Physics, University of California Santa Barbara, Santa Barbara, CA 93106, USA
12
Department of Physics (Astrophysics), University of Oxford, DWB, Keble Road, Oxford OX1 3RH, UK
13
Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto M5S 3H4, Ontario, Canada
14
Ioffe Physico-Technical Institute of the Russian Academy of Sciences, St. Petersburg, Russian Federation
15
University of Maryland, Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA
16
Center for Space Plasma & Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899, USA
17
Department of Physics and Mathematics, Aoyama Gakuin University, Kanagawa, Japan
18
Max-Planck-Institut f
¨
ur extraterrestrische Physik, D-85748 Garching, Germany
19
Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721, USA
20
Space Research Institute, Moscow, Russian Federation
21
Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA
Received 2011 January 21; accepted 2011 August 7; published 2011 October 19
ABSTRACT
We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf
(SN 2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SN distance is
∼
=
218 Mpc,
greater than GRB 980425/SN 1998bw and GRB 060218/SN 2006aj, but smaller than the other SNe firmly
associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar
48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research
in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we
compare the properties of PTF 10bzf with those of SN 1998bw and other broad-line SNe. The optical luminosity
and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of
56
Ni,
between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or
radio counterpart to PTF 10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying
X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB 030329 or GRB 031203. Early-time
radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the
presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB 030329
and GRB 031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf,
we find that no GRB in the interplanetary network catalog could be associated with this SN.
Key words: gamma-ray burst: general – radiation mechanisms: non-thermal – supernovae: general – supernovae:
individual (PTF 10bzf)
Online-only material: color figures
1. INTRODUCTION
The Palomar Transient Factory
23
(PTF; Law et al. 2009;Rau
et al. 2009) is an ongoing project optimized for detecting optical
transients in the local universe. One of its main objectives is
the collection of a large sample of core-collapse supernovae
(SNe; e.g., Arcavi et al. 2010), for which multicolor optical light
curves and spectra can be obtained through dedicated follow-up
resources.
The explosive death of a SN massive progenitor occurs when
its iron core collapses to a neutron star or a black hole. Core-
22
Einstein Fellow.
23
http://www.astro.caltech.edu//ptf/
collapse SNe are either of Type Ib/Ic if the hydrogen envelope
of the progenitor is lost, or else of Type II (Filippenko 1997).
While the total kinetic energy released in the explosion is of
the order of 10
51
erg, roughly the same as the energy of the jet
that makes a gamma-ray burst (GRB), core-collapse SNe are
in general not accompanied by highly relativistic mass ejection
and are visible from all angles.
The discovery of an association between a Type Ic SN and
a long-duration GRB in 1998 (Galama et al. 1998; Kulkarni
et al. 1998) strongly supported the collapsar scenario (e.g.,
MacFadyen & Woosley 1999a;M
´
esz
´
aros 2006; Woosley &
Bloom 2006, and references therein). This was one of the most
unusual Type Ic SNe seen up to that time: more luminous than
typical Type Ic SNe, with broad lines and strong radio emission
1

The Astrophysical Journal, 741:76 (13pp), 2011 November 10 Corsi et al.
Tab le 1
Summary of Light-curve Properties
SN Type Associated d
L
M
R
M
Ni
/M

GRB (Mpc) (mag)
SN 1998bw
a
Engine-driven BL-Ic GRB 980425 37 −19.36 ± 0.05 0.4–0.5
SN 2003dh
b
Engine-driven BL-Ic GRB 030329 810 ≈−19 0.25–0.45
SN 2003lw
c
Engine-driven BL-Ic GRB 031203 477 −19.90 ± 0.08 0.45–0.65
SN 2006aj
d
Engine-driven BL-Ic GRB 060218 140 −18.81 ± 0.06 0.21
SN 2010bh
e
Engine-driven BL-Ic GRB 100316D 261 ... ...
SN 2009bb
f
Engine-driven BL-Ic None 40 −18.56 ± 0.28 0.16–0.28
SN 2003jd
g
BL-Ic None 78 −18.94 ± 0.30 0.26–0.45
SN 2002ap
h
BL-Ic None 7.8 −17.50 ± 0.32 0.06–0.12
Notes. See also Woosley & Bloom (2006, and references therein) for a recent review.
a
Galama et al. (1998), Iwamoto et al. (1998), and Nakamura et al. (2001).
b
Hjorth et al. (2003), Matheson et al. (2003), and Deng et al. (2005).
c
Malesani et al. (2004) and Mazzali et al. (2006b).
d
Mazzali et al. (2006a), Pian et al. (2006), Soderberg et al. (2006a), and Valenti et al. (2008).
e
Starling et al. (2010).
f
Pignata et al. (2011).
g
Mazzali et al. (2005), Valenti et al. (2008), and Drout et al. (2010).
h
Gal-Yam et al. (2002), Mazzali et al. (2002), Foley et al. (2003), and Drout et al. (2010).
indicating a relativistic expansion speed (Γ ∼ 2; Kulkarni et al.
1998).
Since 1998, a total of five associations between GRBs
and SNe have been spectroscopically confirmed (Table 1).
GRBs with spectroscopically confirmed SNe are generally
underluminous and sub-energetic in comparison to typical long
GRBs. A notable exception, though, is GRB 030329 associated
with SN 2003dh that represents the first solid evidence for a
connection between ordinary GRBs and SNe (Garnavich et al.
2003; Hjorth et al. 2003; Kawabata et al. 2003; Matheson et al.
2003; Stanek et al. 2003).
After GRB 030329, an SN-like brightening was reported at
the position of GRB 031203, and SN 2003lw was then pho-
tometrically (Bersier et al. 2004; Cobb et al. 2004; Malesani
et al. 2004; Gal-Yam et al. 2004) and spectroscopically
(Malesani et al. 2004) confirmed to be associated with this GRB.
Broad spectral features similar to SN 1998bw also characterized
SN 2003lw.
The understanding of the GRB–SN connection has further
progressed thanks to the discovery of GRB/XRF 060218 (Pian
et al. 2006; Modjaz et al. 2006; Sollerman et al. 2006; Ferrero
et al. 2006), associated with SN 2006aj. The prompt spectrum of
this GRB showed evidence for a typical non-thermal component
(as observed also in ordinary GRBs) plus a thermal component.
This last suggested that the shock breakout of an associated SN
was for the first time being observed (Campana et al. 2006;
Waxman et al. 2007). A different central engine (a magnetar
rather than a black hole) was also suggested by several authors to
explain the long duration and lower luminosity of GRB 060218
(Mazzali et al. 2006b; Soderberg et al. 2006a;Tomaetal.2007).
The breakout of a shock through the stellar surfaceispredicted
to be the first electromagnetic signal marking the birth of
a SN. The typical frequency of the emission is in the soft
γ -rays for core-collapse SNe (Grassberg et al. 1971; Chevalier
1976, 1992; Waxman et al. 2007; Chevalier & Fransson 2008;
Katz et al. 2010; Nakar & Sari 2010; Balberg & Loeb 2011;
Katz et al. 2011; Nagakura et al. 2011; Rabinak & Waxman
2011). Since XRF 060218, several shock breakout candidate
events have been proposed (Soderberg et al.
2008; Gezari et al.
2008; Schawinski et al. 2008; Modjaz et al. 2009;Ofeketal.
2010b). Multi-wavelength observations of core-collapse SNe
are fundamental to probe the breakout phase.
The most recent spectroscopically confirmed association
between a GRB and a SN is represented by the case of
GRB 100316D (Starling et al. 2010) and SN 2010bh (Bufano
et al. 2010; Chornock et al. 2010; Wiersema et al. 2010; Cano
et al. 2011). GRB 100316D was a long-duration, soft-spectrum
GRB, resembling GRB 060218 in these properties.
While the above-mentioned observations have clearly estab-
lished a connection between long-duration GRBs and Type Ic
core-collapse SNe, however, what makes some broad-line
Type Ic SNe have an accompanying GRB is still a mystery.
Some long GRBs are clearly not associated with a SN, e.g.,
GRB 060505 (Ofek et al. 2007) and GRB 060614 (Della Valle
et al. 2006; Fynbo et al. 2006; Gal-Yam et al. 2006a). On the
other hand, SN 1997ef remains so far the most energetic pecu-
liar Type Ic SN without a clear GRB association (e.g., Mazzali
et al. 2000), and the broad-line Type Ic SN 2009bb (Soderberg
et al. 2010) showed clear evidence of very high expansion ve-
locity (as normally seen in GRB-related SNe), but no clear GRB
association. However, it is remarkable that all GRB-related SNe
discovered to date are broad-line Type Ic SNe.
Theoretically, in order to produce a relativistic jet from a
collapsing star to power the observed GRB, the stellar core has
to carry a high angular momentum (Woosley & Heger 2006),
so that the spin axis provides a natural preferred propagation
direction for the jet. Moreover, the jet needs to be “clean,” with
small baryon contamination, so that it can achieve a relativistic
speed, with Lorentz factor Γ typically greater than 100 (Piran
1999; Lithwick & Sari 2001; Liang et al. 2010; Abdo et al.
2009b, 2009a, 2009c; Corsi et al. 2010). The outflow also needs
to be collimated, with an aperture angle of the order of 1
◦
–10
◦
for bright GRBs (Frail et al. 2001; Bloom et al. 2003; Liang
et al. 2008; Racusin et al. 2009).
Several types of GRB central engine have been discussed, the
leading candidate being a black hole plus torus system (Woosley
1993; MacFadyen & Woosley 1999b; Proga & Begelman 2003;
Zhang et al. 2003). An alternative candidate is a rapidly
spinning, highly magnetized neutron star (magnetar; e.g., Usov
1992; Thompson et al. 2004; Bucciantini et al. 2008; Metzger
2

The Astrophysical Journal, 741:76 (13pp), 2011 November 10 Corsi et al.
et al. 2011). In the black hole scenario, the first energy source is
the accretion power from the torus. On the other hand, the main
power of a millisecond magnetar engine is its spin-down power.
Whatever the nature of the GRB central engine is, it has
to generate both a narrowly collimated, highly relativistic jet
to make the GRB and a wide-angle, sub-relativistic outflow
responsible for exploding the star and making the SN. To
some extent, the two components may vary independently,
so it is possible to produce a variety of jet energies and SN
luminosities. Woosley & Zhang (2007) have shown that at least
a ∼10
48
erg s
−1
power is required for a jet to escape a massive
star before that star either explodes or is accreted, and lower
energy and “suffocated” bursts may be particularly prevalent
when the metallicity is high, i.e., in the modern universe at low
redshift.
A key prediction of jet models for GRBs (e.g., Piran 2004),
combined with the association of long GRBs with Type Ib/Ic
core-collapse SNe (e.g., Woosley & Bloom 2006), is that some
(spherical) SN explosions will be accompanied by off-axis
GRBs, whose gamma-ray signal is missed because the jet is
not pointed at us, but whose afterglow emission could be visible
at lower energies (from radio to X-rays), once the jet decelerates.
These are also referred to as “orphan afterglows.” Detecting an
off-axis GRB would constitute a direct proof of the popular
jet model for GRBs but, after a decade of efforts (Berger
et al. 2003b; Gal-Yam et al. 2006b; Soderberg et al. 2006a),
such a detection has not yet been achieved. Orphan afterglows
may also be produced by “dirty fireballs,” i.e., cosmological
fireballs whose ejecta carry too many baryons to produce a GRB.
Multicolor, wide-area searches, combined with radio follow-up,
can help to distinguish between off-axis GRBs and dirty fireballs
(Perna & Loeb 1998; Rhoads 2003).
Based on radio follow-up campaigns of Type Ib/cSNe
(Berger et al. 2003b; Soderberg et al. 2010), it is now believed
that no more than 1% of SNe Type Ib/c are powered by central
engines. These observational facts are giving us hints at the
fundamental role that broad-line Type Ic SNe play in engine-
driven explosions. GRBs are known to prefer low-metallicity
dwarf galaxies (e.g., Fynbo et al. 2003; Fruchter et al. 2006), and
to be associated only with a particular subclass of core-collapse
SNe: broad-line Ic events. Previous searches, however, targeted
mostly regular SNe Ib/Ic, residing in giant, high-metallicity
hosts. This is why broad-line Ic events deserve to be studied
with particular attention (Modjaz et al. 2008).
Multi-wavelength follow-up campaigns of broad-line Ib/c
SNe are especially important to probe high expansion veloc-
ities and/or any associated GRB. Moreover, because of their
low (electromagnetic) luminosity compared to GRBs, usually
SNe are observed at non-cosmological distances (z  1). Thus,
broad-line Ib/c SNe also represent a tool to search for nearby
GRB explosions and understand their connection with cosmo-
logical GRBs (e.g., Norris 2002; Podsiadlowski et al. 2004;
Guetta & Della Valle 2007; Liang et al. 2007; Virgili et al.
2009).
In this paper, we present the discovery of a broad-
line Type Ic SN, PTF 10bzf (SN 2010ah), detected by
PTF. This event is interesting for two reasons. First, as
a broad-line SN located at a distance smaller than most
GRB-associated events (except for GRB 980425/SN 1998bw
and GRB 060218/SN 2006aj, see Table 1). Next, this event
enjoyed a rich radio-to-X-ray follow-up campaign. In what
follows, we first describe the observations that led to the
discovery of PTF 10bzf (Section 2
), and its multi-wavelength
follow-up campaign (Section 3). Then, we compare PTF 10bzf
with SN 1998bw and other GRB-associated SNe, and describe
the results of an associated GRB search (Section 4). Finally, we
conclude in Section 5.
2. OBSERVATIONS AND DATA REDUCTION
On 2010 February 23.5038 (hereafter all times are given
in UTC), we discovered a broad-line Type-Ic SN, PTF 10bzf,
visible at a magnitude of R ≈ 18.86 (see Table 2 and Figure 1),
in a 60 s exposure image taken with the Palomar 48 inch
telescope (P48). The SN was not seen in previous images of the
same field taken on 2010 February 19.4392, down to a limiting
magnitude of R>21.3. The SN J2000 position is R.A. =
11:44:02.99, decl. = +55:41:27.6 (Ofek et al. 2010a),
∼
=
5.

2
offset, and at a position angle of
∼
=
5 deg (north through east)
about the position of the galaxy SDSS
24
J114402.98+554122.5.
Digital copies of our data can be downloaded directly from
the Weizmann Institute of Science Experimental Astrophysics
Spectroscopy System (WISEASS
25
; S. E. Yaron et al. 2011, in
preparation).
2.1. Optical Photometry
P48 observations of the PTF 10bzf field were performed
with the Mould-R filter. A high-quality image produced by
stacking several images of the same field (obtained between
2009 May and 2009 June) was used as a reference and subtracted
from the individual images. Photometry was performed relative
to the r-band magnitudes of 10 SDSS reference stars in the
field, including r−i color term corrections, using an aperture of
2 arcsec radius, and applying aperture corrections to account
for systematic errors and errors introduced by the subtraction
process. Aperture corrections are all below ≈0.04 mag. All the
P48 photometry is listed in Table 2. The P48 calibrated light
curve of PTF 10bzf is plotted in Figure 2.
P60 observations were carried out in the B, g, r, i, z bands.
We also observed the PTF 10bzf field with the 1 m telescope
at the Wise observatory
26
using BVRI filters (see Table 2).
For both P60 and Wise observations, image subtraction was
performed using the common point-spread function method via
the “mkdifflc” routine (Gal-Yam et al. 2004, 2008). Errors on
the P60 and Wise data are estimated by using “artificial” sources
at a brightness similar to that of the real SN, with the scatter
in their magnitudes providing an estimate of the error due to
subtraction residuals. The measured magnitude was calibrated
against the magnitudes of SDSS stars in the same field (see
Figure 1). The calibration procedure described in Jordi et al.
(2006) was used for the BVRI data. Calibration errors were
summed in quadrature with the subtraction errors.
2.2. Spectroscopy
Gemini North GMOS
27
(Hook et al. 2004) spectra were taken
on 2010 March 2 (Program ID: GN-2010A-Q-20), using a 1

slit, with the B600 and R400 gratings. The observations had an
24
Sloan Digital Sky Survey (York et al. 2000).
25
http://www.weizmann.ac.il/astrophysics/wiseass/
26
http://wise−obs.tau.ac.il/
27
The Gemini Observatory is operated by the Association of Universities for
Research in Astronomy, Inc., under a cooperative agreement with the NSF on
behalf of the Gemini partnership: the National Science Foundation (United
States), the Science and Technology Facilities Council (United Kingdom), the
National Research Council (Canada), CONICYT (Chile), the Australian
Research Council (Australia), Minist
´
erio da Ci
ˆ
encia e Tecnologia (Brazil), and
Ministerio de Ciencia, Tecnolog
´
ıa e Innovaci
´
on Productiva (Argentina).
3

The Astrophysical Journal, 741:76 (13pp), 2011 November 10 Corsi et al.
Tab le 2
PTF 10bzf Follow-up Campaign
JD-2455251.004 Telescope Δt Band Mag or Flux Reference
(days since Feb 23.504) (s)
−4.061 P48 60 Mould-R >21.3 ATEL 2470
0.000 P48 60 Mould-R 18.863 ± 0.041 ATEL 2470
0.045 P48 60 Mould-R 18.850 ± 0.056 This paper
18.038 P48 60 Mould-R 18.362 ± 0.040 This paper
18.921 P48 60 Mould-R 18.527 ± 0.030 This paper
18.966 P48 60 Mould-R 18.495 ± 0.030 This paper
21.832 P48 60 Mould-R 18.599 ± 0.036 This paper
21.876 P48 60 Mould-R 18.618 ± 0.039 This paper
24.866 P48 60 Mould-R 18.791 ± 0.033 This paper
24.911 P48 60 Mould-R 18.735 ± 0.034 This paper
28.727 P48 60 Mould-R 18.966 ± 0.062 This paper
28.771 P48 60 Mould-R 18.861 ± 0.042 This paper
31.636 P48 60 Mould-R 19.12 ± 0.11 This paper
31.679 P48 60 Mould-R 19.061 ± 0.085 This paper
33.650 P48 60 Mould-R 19.18 ± 0.11 This paper
33.693 P48 60 Mould-R 19.093 ± 0.081 This paper
38.758 P48 60 Mould-R 19.381 ± 0.050 This paper
38.802 P48 60 Mould-R 19.359 ± 0.053 This paper
39.857 P48 60 Mould-R 19.393 ± 0.058 This paper
39.901 P48 60 Mould-R
19.401 ± 0.057 This paper
42.670 P48 60 Mould-R 19.547 ± 0.062 This paper
42.713 P48 60 Mould-R 19.480 ± 0.065 This paper
43.829 P48 60 Mould-R 19.576 ± 0.061 This paper
43.873 P48 60 Mould-R 19.723 ± 0.065 This paper
44.926 P48 60 Mould-R 19.597 ± 0.053 This paper
44.962 P48 60 Mould-R 19.531 ± 0.059 This paper
45.983 P48 60 Mould-R 19.696 ± 0.067 This paper
45.984 P48 60 Mould-R 19.764 ± 0.075 This paper
60.737 P48 60 Mould-R 19.800 ± 0.093 This paper
60.781 P48 60 Mould-R 19.89 ± 0.11 This paper
61.783 P48 60 Mould-R 19.96 ± 0.12 This paper
61.826 P48 60 Mould-R 20.23 ± 0.13 This paper
62.835 P48 60 Mould-R 20.27 ± 0.19 This paper
62.878 P48 60 Mould-R 20.15 ± 0.17 This paper
65.782 P48 60 Mould-R 20.02 ± 0.11 This paper
65.857 P48 60 Mould-R 19.91 ± 0.13 This paper
66.888 P48 60 Mould-R 20.06 ± 0.11 This paper
66.932 P48 60 Mould-R 20.10 ± 0.15 This paper
68.649 P48 60 Mould-R 20.173 ± 0.093 This paper
68.692 P48 60 Mould-R 20.198
± 0.098 This paper
69.771 P48 60 Mould-R 20.299 ± 0.087 This paper
69.815 P48 60 Mould-R 20.159 ± 0.079 This paper
43.840 P60 180 r 19.47 ± 0.13 This paper
43.841 P60 180 i 19.51 ± 0.32 This paper
44.898 P60 180 z 19.86 ± 0.57 This paper
44.901 P60 180 B 21.63 ± 0.75
a
This paper
49.960 P60 180 g 21.17 ± 0.17 This paper
49.962 P60 180 r 19.587 ± 0.070 This paper
49.964 P60 180 i 19.746 ± 0.044 This paper
49.965 P60 180 z 18.99 ± 0.31 This paper
49.967 P60 180 B 21.7 ± 1.0
a
This paper
53.993 P60 180 r 19.72 ± 0.17 This paper
59.895 P60 180 r 19.77 ± 0.20 This paper
65.904 P60 180 i 19.96 ± 0.17 This paper
73.842 P60 180 i 20.15 ± 0.17 This paper
73.844 P60 180 r 20.27 ± 0.17 This paper
78.790 P60 180 r 20.38 ± 0.16 This paper
79.790 P60 180 i 20.50 ± 0.17 This paper
79.794 P60 180 B 21.82 ± 0.83
a
This paper
79.797 P60 180 g 20.88 ± 0.16 This paper
80.771 P60 180 z 19.47 ± 0.45 This paper
81.848 P60 180 r 20.207 ± 0.084 This paper
99.798 P60 180 i 20.99 ± 0.36 This paper
99.801 P60 180 B 22.5 ± 1.3
a
This paper
4

The Astrophysical Journal, 741:76 (13pp), 2011 November 10 Corsi et al.
Tab le 2
(Continued)
JD-2455251.004 Telescope Δt Band Mag or Flux Reference
(days since Feb 23.504) (s)
99.803 P60 180 g 21.27 ± 0.19 This paper
102.774 P60 180 r 20.72 ± 0.12 This paper
102.776 P60 180 B 22.45 ± 0.81
a
This paper
102.780 P60 180 g 21.66 ± 0.31 This paper
103.791 P60 180 i 20.80 ± 0.27 This paper
24 Wise (PI) 600 B 20.34 ± 0.57
b
This paper
24 Wise (PI) 600 V 19.08 ± 0.18
b
This paper
24 Wise (PI) 600 R 18.55 ± 0.11
b
This paper
28 Wise (PI) 600 I 18.42 ± 0.20
b
This paper
28 Wise (PI) 600 B 20.60 ± 0.64
b
This paper
28 Wise (PI) 600 V 19.36 ± 0.27
b
This paper
28 Wise (PI) 600 R 18.79 ± 0.20
b
This paper
28 Wise (PI) 600 I 18.60 ± 0.13
b
This paper
35 Wise (LAIWO) 720 V 20.27 ± 0.42
b
This paper
35 Wise (LAIWO) 720 R 18.87 ± 0.14
b
This paper
35 Wise (LAIWO) 720 I 19.00 ± 0.61
b
This paper
38 Wise (LAIWO) 720 V 19.87 ± 0.69
b
This paper
38 Wise (LAIWO) 720 R 19.57 ± 0.34
b
This paper
7 Gemini 450 g
c
18.6 ± 0.3 ATEL 2470
7 Gemini 450 r
c
18.3 ± 0.3 ATEL 2470
7 Gemini 450 i
c
18.7 ± 0.3 ATEL 2470
12 Keck 240 g
c
18.91 ± 0.3 This paper
12 Keck 2 × 80 r
c
18.48 ± 0.3 This paper
12 Keck 2 × 80 i
c
18.70 ± 0.3 This paper
8.52 UVOT 5 × 10
3
B 18.73 ± 0.10 ATEL 2471
8.52 UVOT 5 × 10
3
U 18.88 ± 0.12 ATEL 2471
8.52 UVOT 5 × 10
3
UVW1 20.07 ± 0.18 ATEL 2471
8.52 UVOT 5 × 10
3
UVW2 20.18 ± 0.26 ATEL 2471
12.80 UVOT 2.5 × 10
3
U 19.68 ± 0.14 ATEL 2471
12.80 UVOT 2.5 × 10
3
UVW1 20.12 ± 0.24 ATEL 2471
8.52 XRT 5 × 10
3
0.3–10 keV <1.3 × 10
−14
erg s
−1
cm
−2
ATEL 2471
12.80 XRT 2.5 × 10
3
0.3–10 keV <2.7 × 10
−14
erg s
−1
cm
−2
ATEL 2471
9.69 CARMA 19.8 × 10
3
95 GHz (−3.7 ± 1.8) × 10
3
μJy ATEL 2473
10.14 Allen 4.8 × 10
3
3.09 GHz < 1.5 × 10
3
μJy ATEL 2472
17.69 EVLA 5.76 × 10
3
4.96 GHz < 33 μJy ATEL 2483
86.71 EVLA 3600 6 GHz < 36 μJy This paper
276.9 EVLA 7200 4.96 GHz < 35 μJy This paper
18.24 WSRT 28.8 × 10
3
4.8 GHz < 126 μJy ATEL 2479
Notes. Magnitudes are not corrected for Galactic extinction (E(B − V ) = 0.012 mag; Schlegel et al. 1998). P48 and P60 observations are calibrated to
SDSS (which is estimated to be on the AB system within ±0.01 mag in the r, i,andg bands; within ±0.02 mag in the z band). P48 errors include (in
quadrature) zero-point calibration errors (0.01 mag), color term errors (0.03 mag), and aperture correction errors (0.04 mag). For P48 detections,
positive counts were collected in the subtracted images at the SN position and magnitudes are above the image 3σ limiting magnitude. All upper limits
are at 3σ .
a
B magnitudes (in the Vega system) calibrated to SDSS using the conversions described in Jordi et al. (2006).
b
BV RI magnitudes (in the Vega system) calibrated to SDSS using the conversions described in Jordi et al. (2006).
c
Synthetic photometry is referred to SDSS g, r, i filters (in the AB system). Errors are dominated by flux calibration errors.
exposure time of 450 s (see Table 2), the airmass was 1.236,
the sky position angle was 191
◦
, and the standard star was
Feige34. Standard data reduction was performed with IRAF
V2.14, using the Gemini 1.10 reduction packages. The Gemini
spectrum of PTF 10bzf is shown in Figure 3. A redshift of
z = 0.0498±0.0003 was derived from the host galaxy emission
lines of O iii,Hα,Hβ,Nii, and S ii. The spectrum (black line in
Figure 3) resembles that of SN 1998bw at a similar epoch (red
lineinFigure3 and Galama et al. 1998) and shows very broad
lines, leading us to classify this SN as a broad-line Ic.
PTF 10bzf was also observed by Keck I/LRIS
28
using a 1

slit, with the 400/8500 grating plus 7847 Å central wavelength
on the red side and with the 400/3400 grism on the blue side.
The exposure time was 2 × 80 s on the red side and 1 × 240 s
on the blue side (see Table 2). Keck data were reduced using the
28
The W. M. Keck Observatory is operated as a scientific partnership among
the California Institute of Technology, the University of California and the
National Aeronautics and Space Administration. The Observatory was made
possible by the generous financial support of the W. M. Keck Foundation.
5

Frequently asked questions

Q1. What are the contributions in "C: " ?

The authors present the discovery and follow-up observations of a broad-line Type Ic supernova ( SN ), PTF 10bzf ( SN 2010ah ), detected by the Palomar Transient Factory ( PTF ) on 2010 February 23. The authors conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. The optical luminosity and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of 56Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. 

Q2. What are the future works mentioned in the paper "C: " ?

Therefore, it is crucial to study them and determine how the GRB-associated SNe differ from the other broad-line Type Ic SNe. The Weizmann Institute PTF partnership is supported in part by grants from the Israeli Science Foundation ( ISF ) to A. G. Joint work by the Weizmann and Caltech groups is supported by a grant from the Binational Science Foundation ( BSF ) to A. G. and S. R. K. A. G. acknowledges further support from an EU/FP7 Marie Curie IRG fellowship and a research grant from the Peter and Patricia Gruber Awards. In an era in which ground-based gravitational wave detectors such as LIGO33 and Virgo34 are approaching their advanced configurations, nearby GRBs represent promising candidates for the detection of gravity waves ( e. g., Kobayashi & Mészáros 2003 ; Kokkotas 2004 ; Woosley & Bloom 2006 ; Piro & Pfahl 2007 ; Corsi & Mészáros 2009 ; Ott 2009, and references therein ). 

Q3. Why are SNe observed at non-cosmological distances?

because of their low (electromagnetic) luminosity compared to GRBs, usually SNe are observed at non-cosmological distances (z 1). 

Q4. What is the first electromagnetic signal associated with a SN?

The breakout of a shock through the stellar surface is predicted to be the first electromagnetic signal marking the birth of a SN. 

Q5. What type of GRB engine has been discussed?

Several types of GRB central engine have been discussed, the leading candidate being a black hole plus torus system (Woosley 1993; MacFadyen & Woosley 1999b; Proga & Begelman 2003; Zhang et al. 2003). 

Q6. What is the significance of the search for SNe associated with nearby GRBs?

The search for SNe associated with nearby (non-γ -ray triggered) GRBs is particularly relevant also in the light of multi-messenger astronomy. 

Q7. How many bursts were detected by the IPN32?

Between 2010 February 12 and 2010 February 23, a total of 14 confirmed bursts were detected by the spacecraft of the IPN32 (Mars Odyssey, Konus-Wind, RHESSI, INTEGRAL (SPI-ACS), Swift-BAT, MESSENGER, Suzaku, AGILE, and Fermi (GBM)). 

Q8. What is the common explanation for the long duration of GRB 060218?

A different central engine (a magnetar rather than a black hole) was also suggested by several authors to explain the long duration and lower luminosity of GRB 060218 (Mazzali et al. 

Q9. What is the important prediction of jet models for GRBs?

A key prediction of jet models for GRBs (e.g., Piran 2004), combined with the association of long GRBs with Type Ib/Ic core-collapse SNe (e.g., Woosley & Bloom 2006), is that some (spherical) SN explosions will be accompanied by off-axis GRBs, whose gamma-ray signal is missed because the jet is not pointed at us, but whose afterglow emission could be visible at lower energies (from radio to X-rays), once the jet decelerates. 

Q10. What is the probability of a burst being detected by the Swift?

if the SN produced a burst below the Fermi threshold, but above the Swift one, the non-detection probability is about 0.86. 

Q11. How much is the X-ray flux of PTF 10bzf?

Rescaling it at 8.5 days and taking into account the SN 1998bw distance, the authors obtain an X-ray isotropic luminosity of ≈3 × 1040 erg s−1, a factor of ∼2.4 below their X-ray luminosity upper limit on PTF 10bzf. 

Q12. How much is the isotropic luminosity of PTF 10bzf?

This corresponds to an isotropic X-ray luminosity of ≈3 × 1042 erg s−1, a factor of ≈40 higher than their X-ray luminosity upper limit on PTF 10bzf. 

Q13. How much did the X-ray flux of GRB 980425 decrease?

The X-ray flux of GRB 980425 about 1 day after the burst was ≈3 × 10−13 erg s−1 cm−2, and it declined at a rate ∝ t−0.2 (Nakamura 1999; Pian et al. 2000). 

Q14. How long after explosion did Berger and Readhead observe the radio peak?

as noted by Berger et al. (2003b), observations performed at ∼10–20 days since explosion sample the radio peak time of Type Ic SNe reasonably well. 

Q15. How does the light curve of PTF 10bzf match the shape of the SN?

As evident from Figure 2, the light curve of PTF 10bzf has to be stretched in time by a factor of ≈1.12 to match the shape of the SN 1998bw light curve. 

Q16. How did the authors find the last upper limit of PTF 10bzf?

As evident from Figure 2, their last upper limit on 2010 February 19 (R > 21.3) indicates that PTF 10bzf probably also evolved more rapidly than SN 1998bw in its pre-peak phase.