Strongly Interacting Supernovae Poonam Chandra National Centre for

Strongly Interacting Supernovae Poonam Chandra National Centre for Radio Astrophysics January 4, 2013

Supernova Classification (based on optical spectra and light curve) Supernovae Hydrogen No Hydrogen Type II Type I Narrow H lines Type IIn Silicon No narrow H lines Type Ia Type IIP/IIL Plateau Type IIP No Silicon Linear Type IIL 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/r 2 Circumstellar wind (1 E-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 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 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 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.

Type IIn supernovae Very diverse stellar evolution and mass loss history. SN 1988 z, extremely bright even after 20 years SN 1994 w faded only in 130 days. SN 2005 gl: LBV progenitor? SN 2006 gy, extremely bright: PISN progenitor? SN 2002 ic, SN 2005 gj: Hybrid between Ia/IIN. SNe 2001 em, 1995 N, 2008 fz: Type Ib/c properties SN 2009 ip: 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 Chandra. XO. 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 2005 kd, 2006 jd, 2008 iy, 2009 ip) In X-rays detected by us: SN 2006 jd, 2010 jl, 2009 ip

Peak radio and X-ray luminosities 2009 ip

Poonam Chandra

Poonam Chandra

Radio/X-ray detected Supernovae SN 2006 jd SN 2010 jl SN 2009 ip SN 2005 kd SN 2008 iy

SN 2006 jd Chandra et al. Ap. J 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, Chandra. XO, XMMNewton

SN 2006 jd- 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.

Radio Absorption Models External free-free absorption

Radio light curves Chandra et al. 2012, Ap. J

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

Radio light curves

Radio Spectra

Radio model of SN 2006 jd Internal free-free absorption with s=1. 6 (r~r-s) Seen in SN 1986 J and SN 1988 Z too. Density of emitting gas r=6 x 106 cm-3. Mass of absorbing gas required to do the observed absorption is 2 x 10 -8 T 45/2 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 2006 jd-XMM spectra

SN 2006 jd-Chandra spectra

SN 2006 jd X-rays Best fit with T>10 ke. V, forward shock origin NH=1. 3 x 1021 cm-2 (Galactic 4. 5 x 1020 cm-2) Detection of 6. 9 ke. V Fe XXVI line (EW=1. 4 ke. V). Possible detection of 8. 1 ke. V Ni XXVIII line 5 Msun Mekal fits the data well and reproduces Fe line. NEI model also fits data well but reproduces very low density ~7 E-3 cm-3. X-ray also gives s=1. 7 (consistent with radio). Density 3 E 6 cm-3

SN 2006 jd- X-ray light curves

SN 2006 jd: Main Results Radio and X-ray both give s~1. 6 -1. 7 (density~1/rs). Mass loss rate ~ 5 x 10 -3 Msun/yr. Shocked gas density 3 x 106 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 2006 jd: Main Results Column density is a factor 50 smaller (1. 3 E 21) than needed to produce the X-ray luminosity (4 E 22). Indicate towards global asymmetry. Lower column density also works against external FFA model. The derived external FFA optical depth from Xray data is ~8 E-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 2010 jl Chandra et al. 2012, Ap. J Letters 2012, 750, L 2 Discovered on 2010 Nov 3. 5 UT in UGC 5189 A (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 >30 Msun. Low metallicity host galaxy, Z~0. 3 Msun. Circumstellar expansion speed 40 -120 km/s.

SN 2010 jl 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 2010 jl Chandra Observations November 2010 October 2011 June 2012 Duration 39. 6 ks 41. 0 ks 39. 5 ks Counts 468 1342 1484 Count Rate 1. 13 E-2 cts 3. 29 E-2 cts 3. 68 E-2 cts Column Density 9. 7 E 23 cm-2 2. 67 E 23 cm-2 6. 6 E 22 cm-2 Temperature >10 ke. V > 10 ke. V

SN 2010 jl Chandra X-ray Spectra Comparison November 2010 October 2011 June 2012

SN 2010 jl Chandra Spectra

SN 2010 jl Chandra Spectra

SN 2010 jl Chandra Spectra

SN 2010 jl Chandra Spectra

SN 2010 jl Main results Column density ~1024 cm-2 (1000 times higher than Galactic absorption). High temperature >10 ke. V 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 ke. V line also points to partially unionized medium.

SN 2010 jl Main results Luminosity (0. 2 -10 ke. V) ~7 x 1041 erg/s, amongst most luminous X-ray supernovae. Since most emission > 10 ke. V, this is spectral luminosity Ejecta speed (v=sqrt(16 k. T/3 m) > 2700 km/s. Mass loss rate > 4 x 10 -3 Msun/year

SN 2010 jl Chandra X-ray November 2010

SN 2010 jl Chandra X-ray October 2011

SN 2010 jl Main results Fe 6. 4 ke. V (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 ke. V) consistent with that expected for this line. Low temperature component fit by powerlaw of ~1. 7 or ~1 -2 ke. V temperature and column density is that of Galactic. Luminosity ~4 x 1039 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 ke. V range. Origin of additional component (NH~8 E 22, k. T~1 ke. V) is not known.

SN 2009 ip 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 2005 gl, 2006 jc etc. ) SN 2009 ip first SN to have both a massive blue progenitor and LBV like eruptions.

SN 2009 ip – 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 (u. Jy) (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 2009 ip- 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<22 nd Sept (3 -sigma~3 E-3 cps). No detection even during the rise time of the event i. e. Sept 22 nd < t < Oct 1 st (3 -sigma 1. 1 E-3 cps). X-ray emission detected starting from Oct 1 st when 2 nd outburst in 2012 reaches UV/optical peak. Detection until Oct 16 th and then no detection from Oct 20 th onwards.

SN 2009 ip – X-ray observations

SN 2009 ip- X-ray observations XMM-Newton observations on 4 th Nov, detection. XMM observations for ~60 ks for EPIC-PN and MOS. Data best fit with T>10 ke. V and NH~1 E 21 cm-2 Flux absorbed 1. 7 E-14 erg/s/cm 2 and unabsorbed 1. 9 E -14 erg/s/cm 2. We use XMM parameters to fit Swift spectrum as well. As best excluded the contamination source as possible. Flux 6 E-15 erg/s/cm 2.

SN 2009 ip – X-ray observations

SN 2009 ip – X-ray observations

SN 2009 ip – 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 2009 ip

Poonam Chandra

Radio Spectral Evolution

Energy scales in various explosions Chemical explosives ~10 -6 Me. V/atom Nuclear explosives ~ 1 Me. V/nucleon Novae explosions few Me. V/nucleon Thermonuclear explosions few Me. V/nucleon Core collapse supernovae 100 Me. V/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 2005 kd 2006 jd 2008 iy 2009 ip 2010 jl 2007 gy 2007 nx 2007 pk 2007 rt 2008 B 2008 J 2008 S 2008 X 2008 aj 2008 am 2008 be 2008 bk 2008 bm 2008 cg 2008 cu 2008 en 2008 es 2008 gm Poonam Chandra 2008 ip 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 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