Chandra Imaging Spectroscopy of Supernova Remnants

1
Chandra Imaging Spectroscopy of Supernova Remnants
Seoul National University, Seoul, Korea, December
18, 2006
Sangwook Park
Department of Astronomy Astrophysics
The Pennsylvania State University
2
SN 1987A in Her Uniqueness

• Brightest supernova observed by mankind since
  1604 (J. Kepler)
• Distance 50 kpc, in the LMC
• Age 19.4 years old as of Jul 2006
• Type II SN
• Progenitor Blue supergiant (Sk -69 202, B3 I)
• Neutrino burst
• gt Core-collapse explosion gt neutron star?
• Most intensively studied SN of all time
• Optical/UV HST and many ground-based
• Radio initial detection, turned on again in
  1990
• X-ray no initial detection, turned on in 1990
• Gamma-ray detected decay lines from 56Co ? decay
  of 56Ni,
• confirming explosive nucleosynthesis
• gt ADS 1000 (1/week) refereed papers (since
  1987)

• Chandra monitoring since 1999
• Twice a year, separated by 6 months
• As of 2006-07, 15 observations performed

3
SN 1987A Chandra Observations

• Date Instruments Exp.
• (since SN)
  (ks)
• 1999-10-6 (4609) ACIS-SHETG 116
• 2000-1-17 (4711) ACIS-S3 9
• 2000-12-7 (5038) ACIS-S3 99
• 2001-4-25 (5176) ACIS-S3 18
• 2001-12-12 (5407) ACIS-S3 49
• 2002-5-15 (5561) ACIS-S3 44
• 2002-12-31 (5791) ACIS-S3 49
• 2003-7-8 (5980) ACIS-S3 45
• 2004-1-2 (6157) ACIS-S3 46
• 2004-7-22 (6359) ACIS-S3 49
• 2004-8-26 (6393) ACIS-SLETG 289
• 2004-9-5 (6404)
• 2005-1-9/13 (6533) ACIS-S3 48
• 2005-7-11/16 (6716) ACIS-S3 44
• 2006-1-28 (6914) ACIS-S3 42
• 2006-7-27 (7095) ACIS-S3 40
• 2007-1-19 (7271) ACIS-S3 38

- Publications Burrows et al. 2000, ApJ, 543,
L149 (Obs 1-2) Park et al. 2002, ApJ, 567, 314
(Obs 1-4) Michael et al. 2002, 574, 166 (Obs 1
3) Park et al. 2004, AdSpR, 33, 386 (Obs
1-6) Park et al. 2004, ApJ, 610, 275 (Obs
1-7) Park et al. 2005, AdSpR, 35, 991 (Obs
1-9) Zhekov et al. 2005, ApJ, 628, L127 (Obs
11) Park et al. 2005, ApJ, 634, L73 (Obs 2-10,
12-13) Zhekov et al. 2006, ApJ, 645, 293 (Obs
2-10, 12-13) Park et al. 2006, ApJ, 646, 1001
(Obs 2-10, 12-13) Racusin et al. 2006, in
preparation HEAD 2006-10 (X-ray radial
expansion Obs 1-15)
Current presentation A review and the latest
results.
4
SN1987A in the LMC
Anglo-Australian Observatory
Sanduleak -69 202 B3I
Before SN
After SN 1987/2/24
5
SN1987A the Ring System (HST)
Space Telescope Science Institute
Tarantula Nebula
6
SN1987A Optical Spot in the Inner Ring
E
E
N
N
S
S
7
SNR 1987A TIME-LAPSE MOVIE (HST)
SuperNova Intensive Study Collaboration
Spot 2
Time-lapse movie of the SN 1987A inner ring Feb.
1998 - Nov. 2003. The optical spots are now
all around the inner ring.
Spot 1
Spot 3
Spot 4
N
Spot 5
S
Spot 6
Jan. 2003
Nov. 2003
8
SNR 1987A Physical Interpretation
Michael et al. 1998
Low speed oblique radiative shock optical/UV
Slower shock in high-density knot soft X-rays
High speed shock radio, hard X-ray
9
SNR 1987A Physical Picture
Optical/Soft X-rays
Hard X-rays
Radio
?
NS/BH
Artistic presentation of SNR 1987A (SAO/CXC)
Cf. Michael et al. 1998
10
SNR 1987A Radio Images (ATCA)
Australian Telescope Compact Array (ATCA)
N
E
Image Credit Bryan Gaensler Lister
Staveley-Smith
11
SNR 1987A First X-ray Images
N
E
ACIS (1999-10) Burrows et al. 2000
ROSAT/HRI (5 pixels) HEASARC/SkyView
Green-Blue ACIS Red HST Contour ATCA
1 arcsecond
12
SNR 1987A ACIS Images 20002006
N
E
Ring-like, asymmetric intensity Developments of
X-ray spots gt becoming a complete ring as the
blast wave arrives the inner ring! Surface
brightness increase gt Now 16 x brighter than
2000 No point source at the center
2001-12-12
2001-04-25
2000-01-17
2000-12-07
2004-01-02
2003-07-08
2002-12-31
2002-05-15
2005-07-11
2005-01-09
2004-07-22
2006-01-28
1 arcsec
13
SNR 1987A ACIS Images 20002005
N
Ring-like, asymmetric intensity Developments of
X-ray spots gt becoming a complete ring as the
blast wave arrives the inner ring! Surface
brightness increase gt Now 12 x brighter than
2000 No point source at the center
E
2001-12-12
2001-04-25
2000-01-17
2000-12-07
2004-01-02
2003-07-08
2002-12-31
2002-05-15
Image not ready
2005-07-11
2005-01-09
2004-07-22
2006-01-28
1 arcsec
14
SNR 1987A ACIS Subband Images 2000-2004
2000-12
2001-12
2002-12
2004-01
0.3-0.8 keV
(HST 2000-11)
(HST 2001-12)
(HST 2001-12)
(HST 2001-12)
0.8-1.2 keV
1.2-8.0 keV
(ATCA 1999-9)
(ATCA 2001-11)
(ATCA 2002-11)
(ATCA 2002-11)
1 arcsec
15
SNR 1987A ACIS Spectrum (2-shock model)
NH 2.35 x 1021 cm-2 Soft component kTs
0.23 0.31 keV ne t 1013 cm-3 s Hard
component kTh 2.2 3.2 keV ne t 2 x
1011 cm-3 s gt ns/nh 20 Abundances fixed
at values obtained from the LETG data N 0.76
O 0.09 Ne 0. 29 Mg 0.24 Si 0.28 Si
0.45 Fe 0.16 (Zhekov et al. 2006)
2000 Jan 2005 July
2004-8 LETG
keV
16
SNR 1987A Soft X-Ray Light Curve
Linear increase of X-ray flux until day 3000.
Rate jump in 1997 (day 3700) coincident with
emergence of optical spots. An exponential
radial density profile can fit the lightcurve
over a decade. An excess became evident since d
6200. Forward shock enters a wall?
0.5-2 keV 3-10 keV
d 3700
d 6200
X-ray (2005-7) vs. Optical (2005-4)
fx n02V0T0-0.6 nr2VrTr-0.6 Where V R3
R t2/3 (Chevalier 1982)
Tr T0 (n0/nr) (e-i equilibrium)
Filling factor of nr increases
e-(Rr-R)/D
0.5-2 keV fractional flux
0.4-1.5/2-5 keV ratio
Fast shock
fx ne2R3T-0.6(e.g., McKee Cowie 1977)
Where T const R3(n0nr e-(Rr-R)/s)2
X-ray Flux (10-13 ergs/cm2/s)
d 6200
Image ACIS 0.5-2 keV Contours HST (Credit
Peter Challis)
Slow shock
Chandra/ACIS
ROSAT (Hasinger et al. 1996)
Day since SN
17
SNR 1987A Soft X-Ray Intensity Ratio
2002-12 to 2000-12
2005-7 to 2002-12
(5791) (5038)
(6716) (5791)
(0.5 2 keV)
(0.5 2 keV)
Contours 2002-12
Contours 2005-7
18
SNR 1987A Hard X-Ray Emission
X-ray (2005-7) vs. Radio (2005-6)
Chandra (0.5 2 keV)
ATCA
X-ray Flux (10-13 ergs/cm2/s)
Image ACIS 3-8 keV Contours ATCA 9 GHz
ROSAT
Chandra (3 10 keV)
Similar rates of hard X-ray and radio gt The same
origin for them? gt Simply due to softening of
X-ray spectrum?
Image ACIS 0.4-0.5 keV Contours ATCA 9 GHz
Day since SN
19
SNR 1987A X-ray Expansion
Racusin et al. 2006 in preparation
X-ray radius vs time. The broadband radial
distribution for each observation is fitted to a
Gaussian in order to estimate the radius of the
SNR as a function of time. Estimated
expansion velocity is 3155 km/s. But, it is
apparently decelerating since d 6200.
vexpansion 3155 /- 111 km/s
20
SNR 1987A X-ray Expansion
Racusin et al. 2006, HEAD
X-ray radius vs time. The broadband
deconvolved image for each observation is fitted
to a ring-like model in order to estimate the
radius of the SNR as a function of time.
Estimated expansion velocity is 1160
km/s. But, it is apparently decelerating since d
6000.
21
SNR 1987A Blast Wave Arrives at the Inner Ring!
HST images optical spots dominate entire inner
ring by 2003 (day 6000). Chandra images
western side brighening up since 2003 (day
6000) and now X-ray morphology is a complete
ring. Soft X-ray lightcurve makes a turn-up at
day 6200, which can be described by the shock
entering a wall. Soft X-ray emission is now
dominated by the decelerated shock since day
6000. Radial expansion rate of the X-ray
remnant reduces since day 6200. Mid-IR
intensity (dust emission from the inner ring)
turns up since day 6000 (Bouchet et al. 2006).
mid-IR vs HST (2005-1)
22
SNR 1987A Dispersed Spectrum (2004)
(Line Profiles Kinematics)
Zhekov et al. 2005,2006
LETG/ACIS-S 289 ks in 2004-8/9 (day
6400) Detailed X-ray lines are resolved with
good stats. Individual line widths doppler
shifts are measures for the first time. The most
reliable abundance measurements.
Ne X
Si XIII
Ne IX
O VIII
Mg XI
Fe XVII
Fe XVII
Mg XII
O VIII
Si XIV
N VII
O VII
V 340 1700 km/s (Where ?? 2??0 /-
2z0(?/?0?? ?)
Angstrom
FWHM (km/s)
South (m 1)
North (m -1)
Angstrom
23
Combined Line Profile 1999-10 (4609)
Eli Michael / JILA
Dispersed Spectrum (HETG) 1999
Vs 3400 700 km/s (consistent with radio
measurements) gt kTi 17 keV Observed kTe
2.5 keV
Line width 2300 300 km/s
(single Gaussian fit)

• Direct evidence for incomplete electron-ion
  thermal equilibration behind shock!

24
SNR 1987A Dispersed X-Ray Spectrum
(Line Ratios)
Zhekov et al. 2005

• Line ratios from individual species
• (He?/Ly? G-ratio of the He-like triplets)
  cannot be satisfied with a single kT-net state.
• X-ray emitting plasma is in multi-kT,
• Ionization states
• (e.g., kT 0.1-2 keV)

He?/Ly?
G-ratio( fi/r)
25
SNR 1987A Neutron Star?
No, NOT Detected
Yet!
gt Stellar ejecta at the center of the SNR might
still be optically thick in X-rays.

• Compare the observed 3-8 keV band images before
  and after adding simulated point sources (with
  various count rates) at the center of the SNR in
  order to determine upper limit (90 ) to point
  source contribution.
• Point source spectrum G 1.7 3.0, NH 2 x
  1021 1024 cm-2 are assumed.
• Based on the image taken on 2004-7-22, a point
  source upper limit is Lx (3-10 keV) 5 x 1033 -
  3 x 1035 ergs s-1

NH 2 x 1021 NH
1 x 1023 NH 1 x 1024 G 1.7 Lx
7.7 x 1033 Lx 1.3 x 1034 Lx 2.5 x
1035 G 3.0 Lx 5.2 x 1033 Lx
1.1 x 1034 Lx 3.0 x 1035
26
SNR 1987A Time-Lapse Movie
(2000-01 to 2005-01)
To be continued
Multi-wavelength collaboration
Chandra/HST/Spitzer/Gemini/ATCA Chandra AO8 740
ksec ACIS/LETG/HETG (PSU/Colorado/MIT)
observations accepted!
PSU/SAO/CXC
27
Combined Line Profile (1999-10 HETG)
Eli Michael / JILA
Dispersed Spectrum (HETG) 1999
Vs 3400 700 km/s (consistent with radio
measurements) gt kTi 17 keV Observed kTe
2.5 keV
Line width 2300 300 km/s
(single Gaussian fit)

• Direct evidence for incomplete electron-ion
  thermal equilibration behind shock!