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Strongly Interacting
Supernovae
Poonam Chandra
National Centre for Radio Astrophysics
January 4, 2013
Supernova Classification
(based on optical spectra and light curve)
Supernovae
Hydrogen
Type II
Narrow H
lines
Type IIn
No Hydrogen
Type I
Silicon
Type Ia
No narrow H
lines
Type IIP/IIL
Plateau
Type IIP
Linear
Type IIL
No Silicon
Type Ib/c
Helium
Type Ib
No Helium
Type Ic
What are Supernovae?
Supernovae are one
of the biggest
explosions in the
Universe after the
Big Bang.
Supernova Energetics
 Energy 1051 ergs. This is 1029 times more than an
atmospheric nuclear bomb explosion.
 One supernova can shine brighter than the whole
galaxy consisting of 200 billion stars.
 As much energy as the Sun will emit in 5 billion
years.
In universe 8 new
supernovae explode every
second.
11-09-13
Evolution of stars
Nuclear reactions inside a heavy star
Evolution of stars
M >8 Msun : core collapse supernovae
• Burns until Iron core is form at the center
• Gravitational collapse
• First implosion (increasing density and temperature at the
center)
• Implosion turns into explosion
• Neutron star remnant at the centre.
• Explosion with 1053 ergs energy
• 99% in neutrinos and 1 % in Electromagnetic
Supernova
Supernovae:
DEATH OF
MASSIVE
STARS
WHY
SUPERNOVAE????????
BIG BANG
75% HYDROGEN
25% HELIUM
HEAVY ELEMENTS????
11-09-13
Nuclear reactions inside a heavy star
Supernovae: seeds of life
Calcium in our bones
Oxygen we breathe
Iron, Aluminum in
our cars
Supernova
Interaction
with the
circumstellar
medium
The Sun
Circumstellar interaction
Explosion
center
Circumst
ellar
medium
density
~1/r2
Circumstellar
wind (1E-5
Msun/Yr)
Forward Shock
~10,000 km/s
Reverse Shock
~1000 km/s
Ejecta
Shock Formation in Supernovae:
Blast wave shock : Ejecta expansion speed is much
higher than sound speed.
Shocked Circumstellar Medium: Interaction of blast
wave with CSM . CSM is accelerated, compressed,
heated and shocked.
Reverse Shock Formation: Due to deceleration of
shocked ejecta around contact discontinuity as
shocked CSM pushes back on the ejecta.
Circumstellar interaction
• Trace back the history of
the progenitor star since
wind velocity ~10 km/s
and ejecta speeds
~10,000 km/s.
•Supernova observed one
year after explosion gives
information about the
progenitor star 1000 years
before explosion!!!
Circumstellar interaction
Forward Shock
~109 K
Hot ejecta
X-rays
Reverse shock
~ 107 K
Synchrotron
Radio
Chevalier & Fransson, astro-ph/0110060 (2003)
Free-free absorption:
absorption by
external medium
Information about mass loss rate.
2
 .

    M uw T


2
ff
3
2
s
R 3
Synchrotron self absorption:
absorption by internal medium
Information about magnetic field and the size.

ssa

2.5
1.5
B
N
rel
Radio
X-ray
• Radio and X-ray
emission
• Radio: Information about
the mass loss rate of the
star, density of the CSM,
size etc.
• X-ray : Density and
temperatures of the
shocked ejecta, chemical
composition
Type IIn Supernovae
 Suggested by Schlegel 1990.
 Most diverse class of supernovae.
 Unusual optical characteristics:
 Very high bolometric and H luminosities
 H emission, a narrow peak sitting atop of
broad emission
 Slow evolution and blue spectral continuum
 Late infrared excess
 Indicative of dense circumstellar medium.
Type IIn supernovae
 Very diverse stellar evolution and mass loss history.
 SN 1988z, extremely bright even after 20 years
 SN 1994w faded only in 130 days.
 SN 2005gl: LBV progenitor?
 SN 2006gy, extremely bright: PISN progenitor?
 SN 2002ic, SN 2005gj: Hybrid between Ia/IIN.
 SNe 2001em, 1995N, 2008fz: Type Ib/c properties
 SN 2009ip: episodic ejections before turning into true
supernova
Karl G. Jansky Very Large
Array
RADIO
TELESCOPES
Giant Metrewave Radio Telescope
X-ray telescopes
XMM
Swift
Multiwaveband campaign to
understand Type IIn supernovae
Chandra, Soderberg, Chevalier, Fransson, Chugai
 Observe most the Type IIN supernovae with the JVLA
telescope (PI: Chandra).
 If detected in radio, follow with Swift-XRT (PI: Soderberg).
 Follow radio bright and/or Swift detected Type IIN supernova
with ChandraXO. Get spectroscopy, separate from nearby
contamination (PI: Chandra).
 If bright enough, do spectroscopy with XMM-Newton (PI:
Chandra).
 NIR photometry with PAIRITEL (PI: Soderberg).
 Low frequency radio follow up with the GMRT
SN IIn Radio Statistics
 Around ~180 Type IIn supernovae
 So far only 81 observed in radio bands
 43 SN IIn observed by us in radio
 Out of 81, only 11 detected in radio bands
 4 detected by us (SN 2005kd, 2006jd, 2008iy, 2009ip)
 In X-rays detected by us: SN 2006jd, 2010jl, 2009ip
Peak radio and X-ray luminosities
1e+42
2006jd
.
1e+41
Type IIn
2005kd
2008iy
1988Z
1986J
2005ip
1998S
1e+40
2009ip
1980K
2002hh
−1
LX−ray(erg s )
1e+39
1e+38
1991em
1e+37
1995N
1998bw
1993J
1979C
1994I
2002ap
2001ig
1999gi
1e+36
1e+35
1987A
1e+34
1e+22
1e+23
1e+24
1e+27
1e+25
1e+26
−1 −1
L6cm (erg s Hz )
1e+28
1e+29
Radio Spectral Luminosity (8 GHz) erg/s/Hz
1e+29
.
.
1e+28
1e+27
1e+26
SN 2005kd
SN 2006jd
SN 1986J
SN 1988Z
SN 1995N
1e+25
1e+24
1
Poonam Chandra
10
100
Days since explosion
1000
100
Poonam Chandra
Radio/X-ray detected
Supernovae
 SN 2006jd
 SN 2010jl
 SN 2009ip
 SN 2005kd
 SN 2008iy
SN 2006jd
Chandra et al. ApJ 2012, 755, 110
 Discovered October 12, 2006 in UGC 4179
 Redshift z=0.0186
 Initial spectrum shows Type Ib and later spectrum
shows IIn
 Radio Observations: VLA(EVLA), GMRT
 X-ray Observations: Swift-XRT, ChandraXO, XMMNewton
SN 2006jd- radio
observations
 With VLA starting from 2007, Nov 21.28 UT
 Epoch: Day 400 until Day 2000.
 Frequency bands: 22.5 (K), 8.5 (X), 4.9 (C) and 1.4 (L)
GHz bands
 With GMRT at three epochs, between 1104 day to 1290
days.
 Frequency bands: 1.4 GHz and 0.61 GHz bands. Not
detected yet in 0.61 GHz bands.
Synchrotron self absorption indicates ejecta speed ~2000-3000 km/s. Too small.
Free-free absorption likely to dominate.
SN 2006jd
Radio Absorption Models
 External free-free absorption
Fn = K1n a t b exp(-t FFA )
t FFA = K 2n -2.1t d
1- g
where a =
;
2
N(E) µ E -g
b = 3m - (3- a )(ms + 2 - 2m) / 2, and
d = m(1- 2s),
Rµt
m
1
and r µ s
r
Radio light curves
Flux Density (mJy)
Chandra et al. 2012, ApJ
L Band
C Band
X Band
K Band
1000
Flux Density (mJy)
100
1000
100
1000
Days since explosion
1000
Days since explosion
Radio Absorption Models
 External free-free absorption
Fn = K1n a t b exp(-t FFA )
t FFA = K 2n -2.1t d
1- g
where a =
;
2
N(E) µ E -g
b = 3m - (3- a )(ms + 2 - 2m) / 2, and
1
and r µ s
r
d = m(1- 2s), R µ t
 Internal free-free-absorption
1- exp(-t int FFA )
Fn = K1n a t b
t intFFA
m
t int FFA = K 3n -2.1t d '
d' is free parameter.
Flux Density (mJy)
Radio light curves
L Band
C Band
X Band
K Band
1000
Flux Density (mJy)
100
1000
100
1000
Days since explosion
1000
Days since explosion
Flux (mJy)
Flux (mJy)
Flux (mJy)
Radio Spectra
Day 408
Day 579
Day 795
Day 845
Day 903
Day 1045
Day 1305
Day 1742
Day 2000
1000
1000
1000
1
10
Freq (GHz)
1
10
Freq (GHz)
1
10
Freq (GHz)
Radio model of SN 2006jd
 Internal free-free absorption with s=1.6 (r~r-s)
 Seen in SN 1986J and SN 1988Z too.
 Density of emitting gas r=6x106 cm-3.
 Mass of absorbing gas required to do the observed
absorption is 2x10-8T45/2 Msun.
 Modest amount of cool gas mixed into radio emitting
region can do the required absorption.
 Source of the cool gas is radiative cooling of the dense
gas in the shocked region.
SN 2006jd-XMM spectra
SN 2006jd-Chandra spectra
SN 2006jd X-rays
 Best fit with T>10 keV, forward shock origin
 NH=1.3x1021 cm-2 (Galactic 4.5x1020 cm-2)
 Detection of 6.9 keV Fe XXVI line (EW=1.4 keV).
 Possible detection of 8.1 keV Ni XXVIII line
 5Msun Mekal fits the data well and reproduces Fe line.
 NEI model also fits data well but reproduces very low
density ~7E-3 cm-3.
 X-ray also gives s=1.7 (consistent with radio).
 Density 3E6 cm-3
SN 2006jd- X-ray light curves
SN 2006jd: Main Results
 Radio and X-ray both give s~1.6-1.7 (density~1/rs).
 Mass loss rate ~ 5x10-3 Msun/yr.
 Shocked gas density 3x106 cm-3.
 X-ray emission well fit with single temperature model,
X-ray coming from forward shocked shell.
 No indication of reverse shock emission
 RS moved back to centre and weakened.
 RS is a cooking shock and the cool shell absorbing this.
SN 2006jd: Main Results
 Column density is a factor 50 smaller (1.3E21) than
needed to produce the X-ray luminosity (4E22).
Indicate towards global asymmetry.
 Lower column density also works against external FFA
model. The derived external FFA optical depth from Xray data is ~8E-4 at 5 GHz on day 1000.
 EW of Fe line much higher than expected. Possible
region is mixing of cool gas could enhance the width of
the line.
SN 2010jl
Chandra et al. 2012, ApJ Letters 2012, 750, L2
 Discovered on 2010 Nov 3.5 UT in UGC 5189A
(z=0.011)
 Discovered magnitude 13.5. Brightened to 12.9.
 One of the brightest apparent magnitude. (Absolute
visual magnitude Mv=-20)
 Archival HST image show progenitor star >30Msun.
 Low metallicity host galaxy, Z~0.3Msun.
 Circumstellar expansion speed 40-120 km/s.
SN 2010jl
 Radio Observations: EVLA : 10 observations from
November 2010 until Now. No detection.
 X-ray observations: At 3 epochs with Chandra
 Novemeber 2010
 October 2011
 June 2012
 Detection at all three epochs in X-ray bands
SN 2010jl Chandra
Observations
Observations
November 2010
October 2011
June 2012
Duration
39.6 ks
41.0ks
39.5ks
Counts
468
1342
1484
Count Rate
1.13E-2 cts
3.29E-2 cts
3.68E-2 cts
Column Density
9.7E23 cm-2
2.67E23 cm-2
6.6E22 cm-2
Temperature
>10 keV
> 10 keV
> 10 keV
SN 2010jl Chandra X-ray
Spectra Comparison
November 2010
October 2011
June 2012
SN 2010jl Chandra Spectra
SN 2010jl Chandra Spectra
SN 2010jl Chandra Spectra
SN 2010jl Chandra Spectra
SN 2010jl Main results
 Column density ~1024 cm-2 (1000 times higher than Galactic
absorption).
 High temperature >10 keV
 High temp indicates forward shock emission
 High absorbing column density not accompanied by high extinction
of the SN.
 This indicates column near forward shock, due to mass loss,
where dust has been evaporated.
 First time X-ray absorption by external medium, that is not fully
ionized by the energetic medium.
 Fe 6.4 keV line also points to partially unionized medium.
SN 2010jl Main results
 Luminosity (0.2-10 keV) ~7x1041 erg/s, amongst most
luminous X-ray supernovae.
 Since most emission > 10 keV, this is spectral
luminosity
 Ejecta speed (v=sqrt(16 kT/3m) > 2700 km/s.
 Mass loss rate > 4x10-3 Msun/year
SN 2010jl Chandra X-ray
November 2010
SN 2010jl Chandra X-ray
October 2011
SN 2010jl Main results
 Fe 6.4 keV (narrow k-alpha iron line) in the first epoch and not in the second
epoch explains that ejecta has moved past the closeby partially unionized
gas.
 The equivalent width (EW=0.2 keV) consistent with that expected for this line.
 Low temperature component fit by powerlaw of ~1.7 or ~1-2 keV temperature
and column density is that of Galactic. Luminosity ~4x1039 erg/s.
 Flux change between the two epochs is 20-30%. Consistent with a
background contaminating ULX source.
 Also looked at the possibility that enhanced 1 kev emission is by the CNO
elements. Not possible as this gives too little absorption in 1.5-3 keV range.
 Origin of additional component (NH~8E22, kT~1keV) is not known.
SN 2009ip
 A Very Unique Type IIn supernova in NGC 7259
 Earlier supernova imposter which had repeated eruptions,
in 2009, 2010.
 Flared in July 2012 and then exploded as supernova in
September 2012 (speed 13,000 km/s)
 Clear link with LBV progenitors (like SN 2005gl, 2006jc
etc.)
 SN 2009ip first SN to have both a massive blue
progenitor and LBV like eruptions.
SN 2009ip – Radio Observations
 Since September 26, 2012 till Dec 2, 2012,
observations at 5 epochs in K (22.5 GHz) and X (8.5
GHz) bands with the JVLA.
Date of
Obs
Frequency Flux Density (uJy)
(GHz)
Sep 26.11
21.19
<132 (3-sigma)
Sep 26.14
8.94
<66 (3-sigma)
Oct 16.06
21.25
79+/-29
Oct 17.12
21.19
108+/-40
Oct 26.04
8.85
44+/-15
Nov 06.06
21.19
52+/-21
Nov 12.97
8.99
48+/-22
Dec 01.99
21.25
46+/-129
Dec 02.93
8.99
174+/-123
Possible
Detection?
SN 2009ip- X-ray
observations
 Swift observations started from Sep 4 until Dec 2012.
 No X-ray emission during the decay of 2012 outburst i.e
t<22nd Sept (3-sigma~3E-3 cps).
 No detection even during the rise time of the event i.e. Sept
22nd < t < Oct 1st (3-sigma 1.1E-3 cps).
 X-ray emission detected starting from Oct 1st when 2nd
outburst in 2012 reaches UV/optical peak.
 Detection until Oct 16th and then no detection from Oct 20th
onwards.
SN 2009ip – X-ray
observations
SN 2009ip- X-ray
observations
 XMM-Newton observations on 4th Nov, detection.
 XMM observations for ~60ks for EPIC-PN and MOS.
 Data best fit with T>10 keV and NH~1E21 cm-2
 Flux absorbed 1.7E-14 erg/s/cm2 and unabsorbed
1.9E-14 erg/s/cm2.
 We use XMM parameters to fit Swift spectrum as well.
 As best excluded the contamination source as
possible. Flux6E-15 erg/s/cm2.
SN 2009ip – X-ray
observations
SN 2009ip – X-ray
observations
SN 2009ip – Main Results
 Studies still going on
 Very interesting supernova as shown LBV like
eruptions in past few years and then exploded as true
supernova.
 Once detected in JVLA C band (5 GHz), we will request
GMRT time in L band.
Summary
 Type IIN supernovae: perfect example of unity in
diversity as each object is very unique.
 Present a systematic study of this class of objects.
 Trend emerging: late radio emission.
 Understanding early absorption.
 Understand trends in luminosity distribution.
 Two classes of supernovae?
Collaborators
 Roger Chevalier, University of Virginia
 Nicolai Chugai, University of Moscow
 Alicia Soderberg, Harvard-Smithsonian
 Claes Fransson, Stockholm Observatory
Peak radio and X-ray luminosities
1e+42
2006jd
.
1e+41
Type IIn
2005kd
2008iy
1988Z
1986J
2005ip
1998S
1e+40
2009ip
1980K
2002hh
−1
LX−ray(erg s )
1e+39
1e+38
1991em
1e+37
1995N
1998bw
1993J
1979C
1994I
2002ap
2001ig
1999gi
1e+36
1e+35
1987A
1e+34
1e+22
1e+23
1e+24
1e+27
1e+25
1e+26
−1 −1
L6cm (erg s Hz )
1e+28
1e+29
Radio Spectral Luminosity (8 GHz) erg/s/Hz
1e+29
.
.
1e+28
1e+27
1e+26
SN 2005kd
SN 2006jd
SN 1986J
SN 1988Z
SN 1995N
1e+25
1e+24
1
Poonam Chandra
10
100
Days since explosion
1000
100
Radio Spectral Evolution
Energy scales in various explosions
Chemical explosives
~10-6 MeV/atom
Nuclear explosives
~ 1MeV/nucleon
Novae explosions
few MeV/nucleon
Thermonuclear explosions
few MeV/nucleon
Core collapse supernovae
100 MeV/nucleon
How Supernovae
impact the
environment?
• Modify the density of the surrounding medium
• Increase the metallicity, hence change the course of star
formation
• Major role in Galaxy evolution
VLA observations of Type IIn
supernovae
SN
2005kd
2006jd
2008iy
2009ip
2010jl
2007gy
2007nx
2007pk
2007rt
2008B
2008J
2008S
2008X
2008aj
2008am
2008be
2008bk
2008bm
2008cg
2008cu
2008en
2008es
2008gm
Poonam Chandra
2008ip
Days
640-1173
404-1030
300-1300
30-90
30-1000
72-418
22-372
2-342
49-329
21
254-336
8-308
12
6-300
40-337
27-268
4-13
252
39-222
156
132
130
52
5-124
Detection
Y
Y
Y
Y
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Distance
64
79
ATel
1182
1297
24
50
71
96
78
66
5.6
27
108
123
4
152
160
50
65
1271
1359
1366
1382
1410
1409
1408
1470
1452,55,65
1865,69
1594
1776
1891