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Infrared Supernova Remnants in the Large Magellanic Cloud

Ji Yeon Seok Seoul National University. Infrared Supernova Remnants in the Large Magellanic Cloud. Contents. Part I: IR survey of the LMC SNRs Introduction Data & Approach Result Discussion: Origin of IR emission Part II: PAH emission from a SNR Introduction Object & Data

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Infrared Supernova Remnants in the Large Magellanic Cloud

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  1. Ji Yeon Seok Seoul National University Infrared Supernova Remnantsin the Large Magellanic Cloud

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

  3. Part I: 1. Introduction 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 The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  4. Part I: 1. Introduction Previous IR surveys of SNRs The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  5. Part I: 2. Data & Approach AKARI & Spitzer Survey of the LMC AKARI LMC survey (Ita+08) • Area: ~10 deg2 • 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) O: SNR MCELS optical Ha, [SII], [OIII](Seok+in prep.) The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  6. Part I: 3. Result Measurement of IR LMC SNRs • 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 Seok+08 The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  7. Part I: 3. Result IR morphology of 28 LMC SNRs AKARI L24 (Seok+08) Spitzer images (Seok+in prep.) The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  8. Part I: 4. Discussion 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 • Tdust: 50-100 K, Mdust: 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) The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  9. Part I: 4. Discussion Comparison to X-ray IR vs X-ray: Tightly correlated. • Both emission mechanisms are physically related. • Dust collisionally heated by hot plasma  good spatial agreement IR visibility • Equilibrium Tdust with Te & ne of hot plasma (Dwek+08) • No IR emission detected from SNRs with Tdust <~40 K • Higher 24/70 um ratio located at higher Tdust IR X-ray IR X-ray B. Williams+06 Seok+08 The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  10. Part I: 4. Discussion Statistical properties of IR SNRs 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 rc/rs, Pei 92) • LMC:rc/rs= 0.22, butMW: rc/rs, =0.9-0.95 Dwek+96 The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  11. 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 Part II: 1. Introduction PAH emission from SNRs The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

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

  13. Part II: 3. Result Characteristics of PAHs in N49 Distribution of PAH emission • Overall similar to both H2 & 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 • I6.2/I11.3=0.630.31, I7.7/I11.3=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 I6.2/I7.7 (=0.50.27) & I3.3/I11.3 (=0.3-0.43) • Presence of small PAHs (Draine & Li 01, Mori+12) • Consistent with PAH formation from larger grainsbut NOT with preferential destruction of small PAHs by shocks Ionic Neutral The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  14. Part II: 4. Discussion PAH emission mechanism in N49 PAHs swept up by retarded shocks or unshocked with UV heating: emit PAH features • Condition for PAH to exist and radiate in a SNR : Ambient dense medium + Sufficient heating source PAH outside a SNR heated by radiative precursor Too hot (T~7106 K) : rapid destruction The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

  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 (ne, Te) 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. The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe 2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA

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