INFRARED SUPERNOVA REMNANTS IN THE LARGE MAGELLANIC CLOUD Ji Yeon Seok Seoul National University
Feb 22, 2016
INFRARED SUPERNOVA REMNANTS
IN THE LARGE MAGELLANIC CLOUD
Ji Yeon SeokSeoul National University
Contents Part I: IR survey of the LMC SNRs
1. Introduction2. Data & Approach3. Result 4. Discussion: Origin of IR emission
Part II: PAH emission from a SNR1. Introduction 2. Object & Data3. Result: PAH properties4. 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, KOREA 2
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 SNRsWell-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 emission2012. 2. 27.
The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA 3
Part I: 1. Introduction
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, KOREA 4
Galactic SNRs LMC 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!!
Part I: 1. Introduction
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:~77 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-wave-
length 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 Universe2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA 5
Part I: 2. Data & Approach
MCELS optical Ha, [SII], [OIII] (Seok+in prep.)
O: SNR
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 wave-lengths
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, KOREA 6
Part I: 3. Result
Seok+08
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, KOREA 7
IR morphology of 28 LMC SNRsPart I: 3. Result
AKARI L24 (Seok+08)
Spitzer images (Seok+in prep.)
IR origin and its correlationN/MIR origin: IRAC CCD (Reach+06) Ionic/molecular line emission PAH emission, Synchrotron emission
24 & 70 um Correlation: good regard-less 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 ra-
tio Ionic/molecular line & PAH emission contri-
bution 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, KOREA 8
Part I: 4. Discussion
IR vs X-ray: Tightly correlated. Both emission mechanisms are physically re-
lated. 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
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, KOREA 9
Seok+08
Part I: 4. Discussion
IR X-ray IR X-ray
B. Williams+06
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, KOREA 10
Part I: 4. Discussion
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, but MW: rc/rs, =0.9-0.95
Dwek+96
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, KOREA 11
Part II: 1. Introduction
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
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, KOREA 12
The 3.3 um PAH features are detected in N49 & N63A for the first time (details of N49: Seok+12).
Part II: 2. Object & Data
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 de-
tected at Spitzer IRS spectrum I6.2/I11.3=0.630.31, I7.7/I11.3=1.250.26 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 (=0.50.27) & I3.3/I11.3 (=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, KOREA 13
Part II: 3. Result
Neutral
Ionic
PAH emission mechanism in N49
Condition for PAH to exist and radiate in a SNR: Ambient dense medium + Sufficient heating
source2012. 2. 27.
The Second AKARI Conference: Legacy of AKARI: A Panoramic View of the Dusty Universe2012 February 27-29, Ramada Plaza Hotel, Jeju, KOREA 14
Part II: 4. Discussion
Too hot (T~7106
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
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 indica-tor 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, KOREA 15