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 narrow H lines Type IIP/IIL No Hydrogen Type I Silicon Type Ia No Silicon Type Ib/c Plateau Type IIP Linear Type IIL 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 End stages of massive stars. Nuclear fusion. Radiative energy. In the end nuclear fuel exhausted. Gravitational collapse. Star evolved for millions Of years. End collapse (implosion+ explosion) in few millisec. Explosion- 99% neutrino. 1% EM. NS or BH at the center.

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 Circumstellar 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. Synchrotron self absorption: absorption by internal medium Information about magnetic field and the size.

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 X-ray Tell the regions of Radio and X-ray emission…where do they come from…. Give the details like wind velocity, temperatures of the shocked region, ejecta speeds

Type IIn Supernovae Very high bolometric and Ha luminosities Suggested by Schlegel 1990. Most diverse class of supernovae. Unusual optical characteristics: Very high bolometric and Ha luminosities Ha emission, a narrow peak sitting atop of broad emission Slow evolution and blue spectral continuum Late infrared excess Indicative of dense circumstellar medium. Radio observed between 1 year to 5000 days

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

RADIO TELESCOPES Karl G. Jansky Very Large Array 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 2009ip

Poonam Chandra

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, XMM- Newton

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 Synchrotron self absorption indicates ejecta speed ~2000-3000 km/s. Too small. Free-free absorption likely to dominate.

Radio Absorption Models External free-free absorption

Radio light curves Chandra et al. 2012, ApJ Extenal FFA does not fit and gives m>1

Radio Absorption Models External free-free absorption Internal free-free-absorption

Radio light curves Extenal FFA does not fit and gives m>1

Radio Spectra

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 Mass swept by FS 3Msun.

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 X- ray 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. Seen in SN 2001em too.

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 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

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. The high temperature of the thermal X-ray emission indicated a forward shock origin. The high absorbing column density to the X-ray emission is not accompanied by high extinction to the SN, showing that the column is probably due to mass loss near the forward shock wave where any dust has been evaporated. SN 2010jl is an example of a case where, owing to the sensitive Chandra observations, for the first time we are able to see X-ray absorption by an external medium that is not fully ionized by the energetic radiation, as well as the evolution of this absorption.

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 The high temperature of the thermal X-ray emission indicated a forward shock origin. The high absorbing column density to the X-ray emission is not accompanied by high extinction to the SN, showing that the column is probably due to mass loss near the forward shock wave where any dust has been evaporated. SN 2010jl is an example of a case where, owing to the sensitive Chandra observations, for the first time we are able to see X-ray absorption by an external medium that is not fully ionized by the energetic radiation, as well as the evolution of this absorption.

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. The high temperature of the thermal X-ray emission indicated a forward shock origin. The high absorbing column density to the X-ray emission is not accompanied by high extinction to the SN, showing that the column is probably due to mass loss near the forward shock wave where any dust has been evaporated. SN 2010jl is an example of a case where, owing to the sensitive Chandra observations, for the first time we are able to see X-ray absorption by an external medium that is not fully ionized by the energetic radiation, as well as the evolution of this absorption.

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 (GHz) Flux Density (uJy) Sep 26.11 21.19 <132 (3-sigma) Sep 26.14 8.94 <66 (3-sigma) Oct 16.06 21.25 79+/-29 Oct 17.12 108+/-40 Oct 26.04 8.85 44+/-15 Nov 06.06 52+/-21 Nov 12.97 8.99 48+/-22 Dec 01.99 46+/-129 Dec 02.93 174+/-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 2009ip

Poonam Chandra

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 Modify density After explosion, shock ejecta Increase metalicitty

VLA observations of Type IIn supernovae SN Days Detection Distance ATel 2005kd 640-1173 Y 64 1182 2006jd 404-1030 79 1297 2008iy 300-1300 2009ip 30-90 24 2010jl 30-1000 N 50 2007gy 72-418 - 2007nx 22-372 2007pk 2-342 71 1271 2007rt 49-329 96 1359 2008B 21 78 1366 2008J 254-336 66 2008S 8-308 5.6 1382 2008X 12 27 1410 2008aj 6-300 108 1409 2008am 40-337 1408 2008be 27-268 123 1470 2008bk 4-13 4 1452,55,65 2008bm 252 1865,69 2008cg 39-222 1594 2008cu 156 152 2008en 132 160 2008es 130 1776 2008gm 52 2008ip 5-124 65 1891 2009ay 15 95 2009dn 55 2009fs 7 2070 VLA observations of Type IIn supernovae Poonam Chandra