From koji.kawabata@nao.ac.jp Thu Aug 22 20:06:22 2002
Dear David,
Thank you for your comments.
I also think that only a small part of SNe may have jets.
The case of SN 2002ap might be somehow minor.
It would not be clever to carry out spectropolarimetry for
many supernova in order only to find a redshifted polarized flux.
The general purpose of SN spectropolarimetry should be, I think,
to know the major physical process of the outburst through the
asphericity of the photosphere/ejecta.
Accurate interpretation needs a sophisticated, realistic modeling,
which I am not ready to do.
The proposal was originally written by Lifan Wang and his colleagues.
They had asked Ken to submit their proposal with Ken and FOCAS team,
and I submitted it as the PI after all.
The main theme of the scientific justification in the proposal was
the asymmetry of the outburst, and we hardly mentioned jets.
I think it was proper.
To make sure I will attach the source of the proposal below.
It would be better to keep the general purpose again in the
next proposal (although I do not know whether Wang ask us
to submit together again). Of course, if any more exciting theme
(or particular target) exists, we should include it or submit separately.
Sincerely yours,
Koji
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% Template for Subaru proposals (as of S02B)
%
% If you are using LaTeX2e, you should uncomment the \documentclass and
% \usepackage lines and comment the \documentstyle line.
\documentclass{article}
\usepackage{subaru,epsf}
%\documentstyle[subaru,epsf]{article}
\begin{document}
%
% Uncomment this line if this is an Open Use Intensive Program
%\intensive
%
% Enter your title here; it should fit on one line when printed
\title{Asymmetries: Thermonuclear Explosions, Core-Collapse, and GRBs}
% Enter the Principal Investigator's information here
\PIfirstname {Koji}
\PIinitial {S.}
\PIlastname {Kawabata}
\PIinstitute {Optical and Infrared Astronomy Division, National
Astronomical Observatory of Japan}
\PIaddress {Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan}
\PIemail {koji.kawabata@nao.ac.jp}
\PIphone {+81-422-34-3533}
\PIfax {+81-422-34-3545}
% Uncomment ONE of the following lines to indicate the scientific category
%\SolarSystem
%\NormalStars
%\ExtrasolarPlanets
%\StarandPlanetFormation
\CompactObjectsandSNe
%\MilkyWay
%\LocalGroup
%\ISM
%\NearbyGalaxies
%\StarburstGalaxies
%\AGNandQSOActivity
%\QSOAbsorptionLinesandIGM
%\ClustersofGalaxies
%\GravitationalLenses
%\HighzGalaxies
%\DeepSurveys
%\LargeScaleStructure
%\CosmologicalParameters
%\Miscellaneous
% Enter your abstract here. Please ensure it fits in the space provided.
\begin{abstract}
Asymmetry plays an important role in the explosions of stellar objects to
generate supernovae (SN) of various types, in gamma-ray bursts (GRBs), and
perhaps in the SN/GRB connection.
We propose to conduct a systematic search for signatures of asphericity in
these transient events with the goal of understanding the asymmetric nature
and the corresponding physical origins of these events. Asymmetric line
profiles, fine structured spectral lines, and profile differences between
lines from different chemical species are all signatures of asymmetry.
Such data are rare and are only available for the brightest supernovae
such as SN 1987A, SN 1993J and SN 1996cb. To reach these goals, spectra of
S/N ratio above 50 are required at a resolution of around 2-5 \AA\ for
a wide range of magnitudes from around V $\sim$ 12 to V $\sim$ 23. Proper
time coverage is critical for these observations and
the late nebular phase (when the supernova ejecta are optically thin) is
particularly important. While the general theme of this proposal is
spectral signatures of asymmetry, we expect these efforts to tremendously
improve the current situation of the spectral coverage of late-time
supernovae and to open new ground for supernova research.
\end{abstract}
% Enter name and institution of each Co-I
% e.g., \CoI{I. Newton}{University of Cambridge}
\begin{investigators}
\CoI{K. Nomoto,~K. Maeda,~J. Deng}{\hspace*{4em}Univ. of Tokyo}
\CoI{G. Kosugi,~T. Sasaki}{Subaru Telescope, NAOJ}
\CoI{T. Takata,~K. Aoki}{Subaru Telescope, NAOJ}
\CoI{M. Iye}{Opt.\& IR Astron. Div., NAOJ}
\CoI{D. Baade}{ESO, Germany}
\CoI{L. Wang}{LBNL, USA}
\CoI{P. H\"oflich,~J. C. Wheeler}{Univ. of Texas, USA}
\CoI{D. J. Jeffery}{New Mexico Tech, USA}
\CoI{P. Mazzali}{Trieste Observatory, Italy}
\end{investigators}
% List all relevant publications here.
\begin{publications}
\footnotesize
Howell, D. A., H\"oflich, P., Wang, L., \& Wheeler, J. C. 2000, ApJ,
556, 320:
{Evidence for Asphericity in a Type Ia SN 1999by}
\smallskip\\
Kawabata, K. S., et al. 2001, ApJ, 552, 782:
{Spectropolarimetric Evidence of Asymmetric Outburst
in the Fast Nova V1494 Aquilae}
\smallskip\\
Kawabata, K. S., Kosugi, G., Sasaki, T., Ohyama, Y., Kashikawa, N.,
Saito, Y., Iye, M, Nomoto, K. 2002, IAUC, 7835:
{Supernova 2002ap}
\smallskip\\
Maeda, K., Nakamura, T., Nomoto, K., Mazzali, P. A., Patat, F.,
Hachisu, I. 2002, ApJ, 565, 405: {Explosive Nucleosynthesis in
Aspherical Hypernova Explosions and Late-Time
Spectra of SN 1998bw}
\smallskip\\
Mazzali, P. A., Deng, J., Maeda, K., Nomoto, K., et al. 2002,
ApJL, in press: {The Type Ic Hypernova SN 2002ap}
\smallskip\\
Mazzali, P. A., Nomoto, K., Patat, F., \& Maeda, K. 2001,
ApJ, 559, 1047:
{The Nebular Spectra of the Hypernova SN 1998bw
and Evidence for Asymmetry}
\smallskip\\
Wang, L., H\"oflich, P., Khokhlov, A., Wheeler, J., Baade, D.,
and the SINS team, ApJ, submitted:
{The Bipolar Ejecta of Supernova 1987A}
\smallskip\\
Wang, L., Howell, A. D., H\"oflich, P., \& J. C. Wheeler, 2000,
ApJ, 550, 1030:
{Polarimetry of Core-collapse Supernovae}
\smallskip\\
Wang, L., Baade, D., Fransson, C., H\"oflich, P., Lundqvist, P.,
Wheeler, J. C. 2002, IAUC, 7820: {Supernova 2002ap in M74}
\smallskip\\
Wang, L., \& Wheeler, J. C. 2002, Sky \& Telescope, 103, part no 1, 40:
{Supernovae are not round}
\smallskip\\
\end{publications}
% For each observing run, enter the instrument, number of nights requested,
% lunar phase (Dark/Gray/Bright), preferred dates, acceptable
% dates, and % configuration. Fractional nights are now accepted.
% e.g., \run{IRCS}{1}{Bright}{Dec/early Jan}{Nov--Feb}{K grism}
\begin{observingrun}
\run{FOCAS}{2}{Gray}{Oct/Mar}{Oct/Mar}{Gr. 300B+SY47 or L600 }
% Enter the minimum acceptable number of nights to achieve your science
% goals. You may leave this empty if you require your full request.
\minnights{1.5}
\end{observingrun}
% Uncomment the following line if you do not want the technical reviewer
% to see your target names
%\hidetargets
% Enter your targets here: name, RA, dec, equinox, magnitude
% e.g., \target{4C~41.17}{06 50 52.10}{+41 30 30.5}{J2000.0}{$K=19.1$}
\begin{targets}
\target{SN~2002XX or SN~2003XX}{TBD}{TBD}{J2000.0}{$V=12$--$20$}
%\target{SN~2001ig}{22 57 30.69}{-41 02 25.9}{J2000.0}{$V\sim23.0$}
\target{SN~2002ap}{1 36 23.85}{+15 45 13.2}{J2000.0}{$V\sim 19$--$23$}
%\target{SN~2001gd}{23 23 23.89}{+36 38 17.7}{J2000.0}{$V\sim23.0$}
\end{targets}
% Explain any scheduling requests noted above.
\scheduling{This is a ToO (Target of Opportunity) observation. We
would like to ask re-arrangement of observing schedule to the
observatory (or the TAC) when a proper target appears.}
% Add any further instrumentation requirements, or details of your own
% instrument.
\instruments{We will need FOCAS with Grating 300B and order filters to obtain
high S/N ratio spectra in the wavelength range of 3500\AA\ and 9400\AA.}
% Please briefly describe your experience, ability, need of assistance,
% etc. for making observations with Subaru
\experience{The PI and several Co-Is belong to the FOCAS instrument
team and have sufficient experiences with observations with FOCAS
and the Subaru telescope. We need only normal assistance by the support
astronomer and by the telescope operator.}
% Briefly describe your backup proposal. Please include target names so
% conflicts with accepted proposals can be spotted.
\backup{Spectroscopy of SN Ic Hypernova SN 2002ap. We have observed SN 2002ap
in 2002 February and March with FOCAS spectropolarimetry mode.
The object is also observed by the ESO-VLT in spectropolarimetry mode, and
by the SINS team with the HST. We have full access to all these data.
Further spectroscopy of the evolved phase is still needed. Late
time spectroscopy will provide more insight into the nature of the
supernova explosion.}
% Put the Observing Method and Technical Details here.
\begin{technicalinfo}
We use the typical long-slit spectroscopic mode of the FOCAS.
The wavelength range of our observation is 3500--9400 A.
To achieve the spectral resolving power of 500, we use the 300B
grism and the 0.8$''$ offset slit with the order-cut filter of either
SY47 or L600. We will read out whole CCDs and use the normal readout
speed. Binning factors of CCD and the exposure time depend
on the magnitude of each supernova at the time of observation.
For SN Ia before maximum and V $\sim$ 13, we should target accuracies about
0.1-0.2\%/pixel, which will increase the exposure time considerably.
For SN II, and SN Ibc, we will be targeting accuracy about 0.2-0.4\%/pixel
but the first data set should be around 0.2\%/pixel.
These are achieved by one or several exposure(s) of 3 to 30 minutes.
Since the targets are point-like sources and no rotation of position
angle of the Cassegrain rotator is necessary, it should be always kept at
0.0 deg for any target.
In the case of the spectropolarimetry (if possible), we also use the
Wollaston prism and the half-wave plate. A typical observing sequence
will consiste of four integrations at the 0, 45, 22.5 and 67.5degs
positions of the half-wave plate. Necessary S/N in each integration
will be 0.1\%/pixel.
Beside the target observation, we carry out a calibration observation
of a proper spectrophotometric standard star under the same observing
mode with the target observation (except for changing the slit width
to 2$''.$0).
For all our observation, we use the ADC (atmospheric dispersion
corrector) of Cassegrain focus.
\end{technicalinfo}
% If this proposal is a continuation of an accepted proposal (or a
% resubmission of one which was weathered out for example), enter the
% proposal ID and title here.
\continuation{}{}
% If these observations are intended to be part of a student's thesis,
% enter the student's name and thesis title.
\thesis{}{}
% Enter your previous Subaru runs from the last 3 years. Enter year/month,
% Proposal ID, PI name, status of data reduction, and status of publications
\begin{previoususe}
\pastrun{2001/3}{S00-022}{K. Nomoto}{Data reduced/analyzed}{\small Two
papers submitted/in press.}
%\pastrun{}{}{}{}{}
\end{previoususe}
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%\begin{moretargets}
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%\end{moretargets}
\scijust
% Enter your scientific justification here (maximum 2 pages, including
% figures and additional references).
\begin{center}{\bf Asymmetries in Stellar Explosions}\end{center}
{\bf Evidence of Asymmetry}
Asymmetry is an important factor in the use of
supernovae as distance indicators because the luminosity can be
view-angle dependent. Asymmetry also provides clues to the physics of
supernova explosions and to the structure of circumstellar matter and
hence to the progenitor evolution.
SN 1987A represented a breakthrough by providing the first detailed
record of the polarimetric evolution of a supernova
(Cropper et al. 1988, MNRAS, 231, 695; Mendez et al. 1988, ApJ, 334,
295). SN 1993J also provided a wealth of data (Trammell, Hines, and
Wheeler 1993, ApJ, 414, L21). Spectropolarimetry probes the
geometrical structures of the supernova (SN) debris which are closely
related to the explosion mechanisms and the progenitor systems.
Core-collapse SNe are found to be generally more highly polarized than
thermonuclear SNe (SN Ia) (Wang et al. 1996, ApJ, 467, 435; 2001, ApJ,
550, 1030; Howell et al. 2001, ApJ, 556, 302), but significant polarization
has also recently been detected recently by the ESO-VLT for SN Ia (Wang et al.
2001, IAUC 7724). Recent Subaru and VLT polarimetry of the hypernova
SN 2002ap yielded the exciting results that ``hypernovae'' can be significantly
polarized and are associated with material moving at speeds above
0.1 c (Wang et al. 2002, IAUC 7820; Kawabata et al. 2002, IAUC 7835).
These observations will be crucial to understand the photometric and
spectral behavior of SN 2002ap, and may help to construct a coherent
physical model of these energetic events.
Although perhaps most powerful, polarimetry is not the only method to
probe the geometry of supernovae. Extensive spectroscopic evidence
exists for the brightest supernovae such as SN 1987A, SN 1993J and SN
1996cb. This evidence includes: (1) fine structured lines in the
optically thick photospheric regime, and in the optically-thin nebular
regime; (2) the global blueshift or redshift of spectral lines; (3) a
differential shift of lines from different chemical species. These
three phenomena were all positively detected for SN 1987A (McCray,
ARA\&A, 31, 175) and SN 1993J (Wang \& Hu 1993, Nat. 369, 380) - the two
brightest supernova in modern history, and to some extent for SN 1985F
(Filippenko \& Sargent 1989, ApJ, 345, L43), SN 1996cb (Qiu et al. 1999,
AJ, 117, 736), and SN 1998bw (Mazzali et al. 2001, ApJ, 559, 1047; Maeda
et al. 2002, ApJ, 565, 405).
{\bf Why is Asymmetry Important?}
First, it is important to know the geometry of a supernova to reliably
use it as a {\it distance indicator}. Supernovae are now proven to be accurate
distance probes and hence one of the foundations of modern cosmology.
Without proper treatment, asymmetry can
introduce uncertainties that distort the distance estimates.
For SN Ia, asymmetry may increase the dispersion in maximum magnitude
and in the magnitude-decline rate relation. Corrections can be applied
by properly averaging a large sample of supernovae, but the nature of the
asymmetry has to be understood to perform the correct statistical average.
This will become more critical as the attempt is made to measure the
equation of state of the ``dark energy.''
The time evolution of any asymmetry is also important, as it will help to
define epochs that are most reliable for distance measurements.
For SN II, the expanding photosphere method requires knowledge
of the geometry of the photosphere. Current methods assume spherical
symmetry. In fact, there is overwhelming evidence of asphericity in SN II.
It is thus important to study SN II at early and late phases to gauge
their geometry at different epochs.
Secondly, it is now clear that observations demand {\it theoretical studies}
to go from old 1-D models to multi-dimensional models.
Multi-dimensional studies of supernovae may resolve fundamental issues
of the explosion mechanisms of supernovae. For core-collapse
supernovae, the long standing problem of making
a theoretical supernova explode may be resolved by introducing
mechanisms such as jet-driven supernovae that do not rely entirely
on neutrino deposition. These highly aspherical
explosion mechanisms will leave their imprints on the chemical structure of
the ejecta and can be probed via high S/N ratio spectroscopy and
spectropolarimetry. For SN Ia, asymmetry may be the result of the binary
nature of the progenitor system. Any observational evidence of asymmetry will
guide theoretical studies of the progenitor evolution and of the
thermonuclear combustion process that causes the explosion.
The combination of observations and multi-dimensional theoretical studies of
supernovae will lead us to 3-D explosion hydrodynamics and 3-D radiative
transfer including spectral polarization. These are technically challenging
projects on both the observational side and the theoretical side.
Observation with Subaru can make a substantial contribution on the
observational side by allowing full spectra analysis at all epochs
of a variety of supernova types.
{\bf Our Strategy}
As we have learned from spectropolarimetry at ESO-VLT, asymmetry is
easier to detect well before optical maximum for SN Ia and long after
optical maximum for core-collapse supernovae. This is easy to understand
for core-collapse supernovae where the asymmetry is likely to originate
from the center of the explosion in portions of the ejecta that become
transparent only in the late nebular phase.
For SN Ia, the asymmetry is perhaps due to the
binary nature of the progenitor system and signs of asymmetry are easier
to detect before optical maximum when the outermost parts of the ejecta are
still observable. The scarcity of supernovae with spectroscopic evidence
of asymmetry resides exactly in the difficulties for systematic observations
of SN Ia well before optical maximum and SN II after the plateau phase.
Current supernova search programs enable supernovae to be routinely
discovered a few days after explosion and make systematic study of
SN Ia at early phases possible. High S/N ratio late time spectra of
core-collapse SNe are difficult for 3-4 meter class telescopes as most of
these SNe are around 21-23 mag.
We plan to follow five core-collapse supernova and two Type Ia supernova
discovered well before optical maximum. For all events, we will attempt
spectropolarimetry whenever possible but would do so especially for
very early SN Ia. Spectropolarimetry of all these supernovae at an early
phase will be attempted at the ESO VLT as well. A comparison of the
results from two different instruments can be an important element
in calibrating the instruments. Problems with the stability of
the Keck instrumentation were discovered in this way.
Although this proposal emphasizes FOCAS spectroscopy, we must note that
spectropolarimetry is the most powerful tool in the study of
supernova asymmetry.
This proposal should therefore be considered a pre-cursor to a more
intense future effort using FOCAS and spectropolarimetry to study the 3-D
structure of supernovae (ref. Figure 1).
\vspace{5ex}
\epsfysize=180mm
\epsfbox{sn02apb.eps}
\noindent
Figure 1. FOCAS spectropolarimetry of SN 2002ap in its early phases:
(a) Flux, (b,c) degree and position angle of observed polarization,
respectively, on each observation night, (d,e) average polarization
in each month.
%% Here I will attach an color EPS figure %%
%% Its JPEG version can be seen at
http://www.astr.tohoku.ac.jp/~kawabata/tmp/SN02APB.jpg %%
\end{document}