1. Ji Yeon Seok Seoul National University

2. Contents  Part I: IR survey of the LMC SNRs 1. Introduction 2. Data & Approach 3. Result 4. Discussion: Origin of IR emission  Part II: PAH emission from a SNR 1. Introduction 2. Object & Data 3. Result: PAH properties 4. Discussion: PAH emission mechanism in a SNR  Summary 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA2

3. The Large Magellanic Cloud  Different environment from the Milky Way Lower metallicity: 1/3 of MW (Pei 92) Lower dust-to-gas ratio: 1/5 of MW (Pei 92) SN rate: 0.5 SNe /100 yr, Ia : CC (II+Ib) = 1 : 11 (Tamman+94) ○ c.f., MW: 2.5 SNe /100 yr, Ia : CC = 1 : 6  Advantages to study LMC SNRs Well-known distance and close to look details (~50 kpc) Uniform and non-biased samples (~50 known SNRs in the LMC) Far from the galactic plane to avoid back/foreground confusion of other IR emission 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA3

4. Previous IR surveys of SNRs 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA4 Galactic SNRsLMC SNRs IRAS 51 IR SNRs out of 157 (Arendt 89) 35 IR SNRs/ 9 candidates out of 161 (Saken+92) 3 IR SNRs out of 4 IR sources (Graham+87), 5 with IR emission out of 25 LMC SNRs (Schwering 89 ) IR & radio comparison for 21 SNRs (including 9 candidates, Filipovic+98a ) Spitzer GLIMPSE & MIPSGAL survey (10  <|l|<65 , |b|<1  ) – 18 NIR SNRs out of 95 (Reach+06), 16 NIR SNRs out of 100 (H. Lee 05) – 39 MIR SNRs out of 121 (Pinheiro Goncalves+11) 39 LMC SNR imaging survey – 4 Type Ia by Borkowski+06 – 4 CC by B. Williams+06 4 out of 6 SNRs with IR emission (R. Williams+06) Limitation Confusion with other Galactic sources is a big problem!! More statistical study for IR LMC SNRs is essential!!

5. AKARI & Spitzer Survey of the LMC AKARI LMC survey (Ita+08)  Area: ~10 deg 2  N3, S7, S11, L15, L24  21 SNRs included (Seok+08) Spitzer SAGE survey (Meixner+06)  Area:~7  7   IRAC (3.4, 4.5, 5.8, 8.0)+ MIPS (24, 70)  All known SNRs covered + Several pointed observations Data approach  Visual inspection to 45 known LMC SNRs (Desai+10)  Comparison with multi-wavelength data ATCA radio, MCELS, Chandra X-ray Images in literatures (e.g., R. Williams+06) 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA5 MCELS optical Ha, [SII], [OIII] (Seok+in prep.) O: SNR

6.  28 out of 45 SNRs detected in the AKARI and/or Spitzer bands! 13 IR SNRs are firstly identified in several IR bands.  Catalog of LMC SNRs (Seok+in prep.) General information: name, position, size, SN type, age + AKARI/Spitzer detection AKARI & Spitzer fluxes ○ Mostly detected at 24 um, and half of SNRs seen at shorter wavelengths Measurement of IR LMC SNRs 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA6 Seok+08

7. 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA7 IR morphology of 28 LMC SNRs AKARI L24 (Seok+08) Spitzer images (Seok+in prep.)

8. IR origin and its correlation N/MIR origin: IRAC CCD (Reach+06)  Ionic/molecular line emission  PAH emission, Synchrotron emission 24 & 70 um Correlation: good regardless of MIR origins!  Comparison with modified BB T dust : 50-100 K, M dust : 0.1-100?? M  Overestimation due to other contribution (e.g., 0.4 M  in N49, Otsuka+10 ) Mixture of multi-component dust (hot dust + cold dust) In general, SNRs interacting with MCs are bright in MIR. MIR color-color diagram  Dust emission: significantly low 8/24 um ratio  Ionic/molecular line & PAH emission contribution High 8/24 ratio, but not clearly separated in the diagram  Rough linear correlation similar to Galactic SNRs (Pinheiro Goncalves+11) 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA8

9. IR vs X-ray: Tightly correlated.  Both emission mechanisms are physically related.  Dust collisionally heated by hot plasma  good spatial agreement IR visibility  Equilibrium T dust with T e & n e of hot plasma (Dwek+08)  No IR emission detected from SNRs with T dust <~40 K  Higher 24/70 um ratio located at higher T dust Comparison to X-ray 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA9 Seok+08 IR X-ray B. Williams+06

10. Statistical properties of IR SNRs 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA10 IR detection rate: 62% (28 out of 45)  c.f., MIPSGAL survey: 32% (39 out of 121, Pinheiro Goncalves+11)  Extrinsic aspect Much severe IR confusion by Galactic disk Biased survey of Galactic SNRs (|b|<1  )  Any intrinsic reason? Lower dust-to-gas ratio than that of the MW Dust composition (graphite to silicate ratio r c /r s, Pei 92 ) ○ LMC: r c /r s = 0.22, but MW: r c /r s, =0.9-0.95 Dwek+96

11. PAH emission from SNRs 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA11 Theoretical expectation  PAH formation by a shock (Jones+96)  Complete destruction by a fast shock (>150 km/s) (Micelotta+10a)  Entrainment of dense clumps in a hot post shock gas for PAH survival (Micelotta+10b) Few observational evidences  Four Galactic SNRs categorized by IRAC colors (Reach+06)  Mostly undetected due to destruction by a fast shock (e.g., Williams+06)  The first detection of PAH emission in SNR N132D (Tappe+06) Large PAH clusters attribute to 15-20 um hump No major features by smaller PAHs due to destruction

12. N63A: Spitzer IRAC Ch3 Chandra X-ray N49: AKARI N3 CO emission 6-cm radio continuum AKARI NIR Spectroscopy: N49 & N63A Phase 3 IRC NG spectroscopy for NIR bright LMC SNRs 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA12 The 3.3 um PAH features are detected in N49 & N63A for the first time (details of N49: Seok+12).

13. Distribution of PAH emission  Overall similar to both H 2 & Br  (H  : contour)  Differences in locality Band ratio: fraction of ionized PAHs  PAH features at 6.2, 7.7, and 11.3 um also detected at Spitzer IRS spectrum  I 6.2 /I 11.3 =0.63  0.31, I 7.7 /I 11.3 =1.25  0.26  Follow the universal linear relation between the ratios  In dense MCs, PAHs in neutral and anionic charge state are dominant (Le Page+03).  High I 6.2 /I 7.7 (=0.5  0.27) & I 3.3 /I 11.3 (=0.3-0.43) Presence of small PAHs (Draine & Li 01, Mori+12) Consistent with PAH formation from larger grains but NOT with preferential destruction of small PAHs by shocks Characteristics of PAHs in N49 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA13 Neutral Ionic

14. PAH emission mechanism in N49  Condition for PAH to exist and radiate in a SNR : Ambient dense medium + Sufficient heating source 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA14 Too hot (T~7  10 6 K) : rapid destruction PAHs swept up by retarded shocks or unshocked with UV heating: emit PAH features PAH outside a SNR heated by radiative precursor

15. Summary  Using IR survey data of the LMC, we examine all known LMC SNRs and find IR emission from 28 SNRs (detection rate: 62%).  IR properties and its origins are investigated based on the IR colors.  X-ray properties (n e, T e ) can be a good indicator of IR emission from a SNR.  PAH features are detected in SNR N49 & N63A.  Ambient dense medium and sufficient heating sources are most likely required to observe PAH emission from a SNR. 2012. 2. 27. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA15