Supernova Remnants and their Progenitors Knox S Long

Supernova Remnants and their Progenitors Knox S. Long Main Collaborators Bill Blair, Kip Kuntz, Paul Plucinsky, Robert Soria, Frank Winkler

Introduction • SNe are bright but fade typically within a year • M 83 has had 6 SNe in the last 100 years • Estimated ages for observed l. SNRs typically 10, 000 -20, 000 years • Expect 600 -1200 SNRs in M 83 • SNRs provide large samples showing where and in what environments SNe explode

Outline • How to find SNRs in galaxies • Optically • Radio • X-ray • Class properties of these samples • First steps toward using SNRs to learn about likely progenitors

Illustrate with M 33 and M 83 M 33 Ch. ASe. M 33 – 1. 4 Ms Plucinsky+2009; Tuellmann+2011 M 83 New 750 ks Chandra program underway

Identifying SNRs optically H [S II] v • Most SNRs in nearby galaxies are identified from [SII]: Ha ratios: SNRs > 0. 4. HII regions ~ 0. 1 • Photo-ionized gas has most S in SIII • Recombining shocks have a wide range of ionization states • Caveat: the separation between SNRs and H II regions drops with surface brightness • Young core-collapse SNRs may show strong [OII] or [O III] • Oxygen is the dominant coolant in the ejecta of core-collapse SNe • Caveat: PNe are also bright O-dominated emission nebulae

The Optical Emission of Ia SNRs SNR 0509 -69. 5 • Most Ia SNRs, including SN 1006 and Tycho emit only in the Balmer lines • Emission arises as neutral H is ionized behind the shock

First Generation Surveys • First generation surveys – 25 -100 SNRs in ~10 galaxies • First search of M 83 using the Dupont 100 inch in late 90 s • 74 nebulae with elevated [SII] : Ha • Most confirmed with spectroscopy Blair+ 2004

nd 2 Generation Surveys Underway • In M 83, 100 more high [S II]: H ratio nebulae SNRs • 73 compact [O III] candidates 33 likely SNRs • L[O III] > Lmax (PN), or • coincident with X-ray sources Winkler+2011

New techniques – [Fe II] • In M 83, we have identified about 20 SNRs in [Fe II] • Some show strong [S II], others do not Blair+2011

Finding SNRs from radio observations • SNRs are extended, non-thermal sources • Steep spectral indexes compared to HII regions • Nearly all Galactic SNRs first discovered as radio sources • Unfortunately, most radio surveys for SNRs too insensitive to date • Will change with EVLA

M 33 & M 83 SNR Radio IDs In M 33, Gordon+1999 found • Of 97 optically identified sources, 53 radio sources coincidences In M 83, Maddox+06 found • 4 historical SNe • 3 non-thermal radio sources coincident with optical SNRs

Finding SNRs in X-rays X-ray H [S II] v • Extended sources • HII regions are typically much fainter in X-rays • Most SNRs are hot thermal plasmas • Spectra are soft compared to compact binaries (and background AGN) • Can be confused with supersoft sources or foreground stars

Chandra image of M 33’s southern spiral arm with known SNRs Long+2010

Bright Chandra SNRs in M 33

X-ray typing of Progenitor • For young SNRs, • X-ray spectra of CC SNRs separable from Ia’s (Hughes, Badenes) • Greater asymmetry may also favor CC SNR (Lopez+2009)

Bright SNRs in M 33 • 7 SNRs with enough counts for spectral analysis • M 33 SNR 21 is ISMdominated expanding into dense molecular cloud (Gaetz et al 2007) • M 33 SNR 31 has a spectrum resembling the core-collapse object E 0102 in the SMC

SNRs have soft X-ray spectra M 33 M 83 S=0. 35 -1. 2 ke. V, M=1. 2 -2. 6 ke. V; Total=0. 35 -8 ke. V

The SNR samples today M 33 M 83 • Samples reflect fact that optical imagery is still more sensitive • Some objects are now being discovered first though with X-rays • With EVLA, radio-identification should become possible

M 33 SNRs - Results • 82 of 137 SNRs > 2 • 61 (of 96) GKL SNRs • 21 other SNR candidates also detected • Chance probability low

M 33: Mostly Middle-Aged SNRs • Median diameters • All= 44 pc • Detected = 38 (32) pc; • Undetected = 54 pc Sample, >2 , >3

Simple Interpretation Just the Facts • Middle age SNRs dominate detections (and sample) • Lx at a single diameter is highly variable • Very large objects are always faint • 60%is detected; 40% is not It’s the environment, stupid! • Lx ~ n 2 R 3 • (0. 35 -2 ke. V) • ~ constant for k. T>0. 3 ke. V • drops rapidly for k. T<0. 3 ke. V • T inversely proportional to M • M(Mo) = 83 T(ke. V)-1 E 51 • Implications • Small diameter objects are faint • Large diameter( Rmax ~ n 1/3) are faint • Lx of intermediate diameter objects strongly dependent on density (n 2)

Are X-ray properties correlated with other properties? • Extreme X-ray SNRs are extreme in most respects • High Lx objects tend to be high LH objects • High Lx objects are generally to be radio detected • Converse is often not true • High LH objects often not X-ray detected • High radio flux objects often not X-ray detected

Would your favorite SNR have been detected in M 33? Radio: No objects as bright as Crab; one possible PWN, coincident with slightly extended, non-thermal radio source X-ray: No bright sources (>4 1035 erg s-1) that are thermal except stars or known SNRs At the distance of M 33, we should have detected • Most of the bright SNRs in the Galaxy and Magellanic Clouds • Most historical SNe - the Crab Nebula, Tycho, Cas A, & Kepler

M 83 Historical SNe

Young SNRs are hard to find beyond the Magellanic Clouds • Ia • II • Hard to separate from HII regions, given no [S II] • Faint in X-rays • Tycho & Kepler, but not SN 1006 would have been seen in Ch. ASe. M 33 study of M 33 • Faint in Radio • O-dominated nebulae • Cas A and G 292+1. 8, N 132 d would have been detected in M 33 • 6 historical SNe in M 83; two found

Example - SNR in NGC 4449 • SNR in NGC 4449 is brightest known Xray SNR • SN not seen but 5075 years old Milisavljevic+2008

Example - SNR in NGC 4449 • SNR in NGC 4449 is brightest known Xray SNR • SN not seen but 5075 years old • X-ray spectrum indicates the product of CC SN • Analysis of HST shows within cluster with turnoff mass of 15 -25 M Long+ in prep Milisavljevic+2008

Example – LMC • MC provide test case of whether local stellar populations can be used to learn about progenitors • Badenes+ 2009 used Harris & Zaritsky 2009 SF history of LMC to study local populations around 4 CC and 4 1 a SNRs • Estimated probabilities for CC Ia • progenitor masses for CC SNRs and • prompt or delayed population events Badenes+2009

Ex. – M 83: Mean Progenitor Mass • Dopita+2010 found 60 SNRs in part of M 83 observed with HST • LH SF rate of ~ 2. 8 M yr-1 • Assume Miller & Scalo IMF • Estimate sample complete for objects <104 yr • 42 objects in this subsample M ~ 24+10 -7 M for progenitors Dopita+2010

Summary • Large samples of SNRs are have been and are continuing to be identified • Optical techniques remain the most effective in finding SNRs • With Chandra and XMM many of these SNRs are being detected, and in few cases, new ones are being identified • Radio observations are lagging, but this picture will change with the EVLA • In M 33: • The sample of SNRs brighter than LX ~4 1035 ergs s-1 is complete • X-ray SNRs in M 33 with LX> 2 1034 ergs s-1 now total 82 • Given that many SNRs are near the luminosity limit, a factor of 2 or 3 in sensitivity would likely reveal the rest. • Characterization of the samples is in its infancy • There are large variations of properties at a given size. • Need to understand local environment to extract class properties of SNRs • Typing of SN progenitors are the major issue for the purposes of this conference