The Slow XRay Expansion of the Northwestern Rim of RX J0852.04622

1
The Slow X-Ray Expansion of the Northwestern Rim
of RX J0852.0-4622

• Satoru Katsuda (Osaka U. / NASA GSFC), Hiroshi
  Tsunemi (Osaka U.), and Koji Mori (Miyazaki U.)
• May 28, 2008 _at_Granada in Spain

This talk is based on ApJ, 678, L35-L38, 2008
2
Outline

• Introduction to RX J0852.0-4622
• Discovery of the SNR, 44Ti g/X-ray line emission,
  a stellar remnant, non-thermal emission up to TeV
  g-ray
• XMM-Newton Observations and Analysis
• Measuring the X-ray expansion of the forward
  shock
• Discussion
• Summary

3
Discovery of RXJ0852.0-4622 (Vela Jr.)
ROSAT all-sky survey
Puppis A SNR
RX J0852-4622
Vela SNR
Above 1.3 keV
0.1-2.4 keV
Aschenbach (1998)
RX J0852.0-4622 was discovered in the
southeastern corner of the Vela SNR ten years ago
(Aschenbach 1998). - High energy X-ray emission
gt Young (lt1500 yr) - Low absorption less than
8x1021 cm-2 gt Near (lt 1kpc)
4
44Ti Decay Line
X-ray hard band
X-ray wideband
(Aschenbach 1998)
(Aschenbach 1998)

• COMPTEL detected g-ray line emission from 44Ti at
  the same time of the discovery of this remnant
  (Iyudin 1998).
• Vela Jr. was the 2nd object, which showed 44Ti
  decay line, following the Cas A SNR. 44Ti ?
  44Sc2g ? 44Cag
• Very young (700 yr) very near (200 pc)

t90 yr
t8 hr
44Ti g-ray line image _at_1.157 MeV Iyudin (1998)
5
Possible Line Feature _at_4keV ASCA SIS0 Chip
ROSAT image of Vela Jr.
He-like 44Ca Ka
ASCA SIS0 spectrum of the northwestern rim
ASCA FOV
Tsunemi (2000)
K-shell emission line from 44Ca was detected by
the ASCA SIS0 chip (Tsunemi 2000). Combining
the amount of 44Ca and the observed flux of 44Ti,
the age of the remnant was estimated to be 1000
yr.
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Possible Line Feature _at_4keV XMM-Newton
Chandra
Line feature (from Ti/Sc)
Chandra ACIS spectrum of the NW rim
XMM-Newton PN spectrum of the NW rim
Line feature
Iyudin (2005)
Bamba (2005)
The line feature around 4 keV was also detected
by XMM-Newton (Iyudin 2005) and Chandra (Bamba
2005). The flux derived by XMM-Newton was
consistent with that estimated by ASCA within a
factor of 2, supporting the young age.
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Doubts for the Young Age and the Near Distance
Reanalysis of the COMPTEL data gt The 44Ti g-ray
emission was only 2-4 s level (Schonfelder
2000). No line feature around 4 keV by ASCA
except for SIS0 (Slane 2001). gtAre emission
lines related to 44Ti really significant? Also,
is this remnant really young? Higher absorption
than that for the Vela SNR (Slane 2001). gtIs
this remnant really near?
RX J0852
44Ti g-ray line(Schonfelder2000)
44Ti g-ray line(Iyudin 1998)
ASCA GIS spectra
1 2 5
Slane (2001)
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Central Compact Object (CCO)
Chandra spectrum

• - Soft thermal spectrum
• - No radio/optical counter part
• No PWN
• Constant luminosity

AX J0852.0-4622
ASCA GIS 0.7-10keV
Kargaltsev (2002)
Slane (2001)

• A compact object, AX J0851.9-4617.4, was
  discovered around the center of this remnant.
• Absorption 3x1021 cm-2 (Slane 2001
  Kargaltsev 2002)
• Age a few 103 yr (Kargaltsev 2002)
• gtIs this point source a stellar remnant of Vela
  Jr.?

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Non-Thermal Emission
Radial profile
Chandra imageBamba 2005
Vela Jr. shows non-thermal dominated spectra from
thin filaments in the NW rim.
Slane 2001
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TeV g-ray Emission
The 2nd shell-type SNR which was spatially
resolved at TeV energies, following
RXJ1713.7-3946 SNR. gt A key object to
understand the origin (Electronic or Hadronic
process?) of TeV g-ray emission.
H.E.S.S. 0.5-20 TeV image
Aharonian (2007)
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Outline

• Introduction to RX J0852.0-4622
• Discovery of the SNR, 44Ti g/X-ray line emission,
  stellar remnant, non-thermal emission up to TeV
  g-ray
• XMM-Newton Observations and Analysis
• Measuring the X-ray expansion of the forward
  shock
• Discussion
• Summary

RX J0852.0-4622 (Vela Jr.) ROSAT all-sky survey
image
XMM-Newton 3 color image
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XMM-Newton Observations of the NW-Rim of Vela Jr.
Obs. Date Exp. Time 1. 04/25/2001 31 ks 2.
06/22/2003 26 ks 3. 11/01/2005 64 ks 4.
10/24/2007 63 ks
6.5 yr
60
- Radius 60 - Age 700 yr
Three-color XMM-Newton image of the NW rim of
Vela Jr. Red 0.4-1keVGreen 1-1.5
keVBlue 1.5-8 keV
Mean angular velocity 35/6.5 yrs
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Astrometric Accuracy
XMM-Newton (Kirsch 2007)absolute astrometric
accuracy 2
Hard band (1.5-8 keV) image
We focused on four point sources in the FOV. All
the sources are detected within the 2-circles in
all the observations. gt2 as a conservative
systematic error
5 arcmin
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Difference Image
Hard band image (2001)
Difference Image (2001-2007)
5 arcmin
The proper-motion can be apparently seen as a
black filament from NE to SW.
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Radial Profile
X-ray image
Proper Motion 5/6.5 yr
Quantitative shift estimation
l shift parameter, k bin We shift the 2001
profile and compare it with 2003, 2005, or 2007
profiles. gt search for l-value which results in
c2 minimum.
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c2 Distributions
2001-20032001-20052001-2007
6arcseconds
The proper motion gt 0.840.23 yr-1. The
expansion rate gt 0.0230.006 (0.84/60) yr-1.
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Vela Jr. is NOT so Young
Expansion Index, m (R?tm), (Expansion Rate) x
(Age).m 1 (free expansion), 0.4 (Sedov), 0.25
(snowplow)
1
m1 (free expansion)
2
3
m0.4 (Sedov)
4
m0.25 (snowplow)
Vela Jr. (This work)
43001200 yr
1700440 yr
5
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Vela Jr. is NOT so Close
Vela Jr. shows non-thermal dominated spectra.
Non-thermal synchrotron radiation in the X-ray
band requires a high shock speed of 3000 km/sec
(e.g., Uchiyama 2003). Distance gt750
(v/3000 km sec-1)(m/0.84 yr-1) pc.
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Outline

• Introduction to RX J0852.0-4622
• Discovery of the SNR, 44Ti g/X-ray line emission,
  stellar remnant, non-thermal emission up to TeV
  g-ray
• XMM-Newton Observations and Analysis
• Measuring the X-ray expansion of the forward
  shock
• Discussion
• Summary

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Probable NON Detection of the 44Ti Line
The initial amount of 44Ti must be at least
1.6x105 times larger than that estimated in the
paper by Iyudin (1998). gt The COMPTEL detection
of the g-ray line at 1.157 MeV seems to have no
relation to Vela Jr.
44Ti g-ray line image Iyudin (1998)
Age Effect the newly determined age, 1700-4300
yr, is at least 2.5 times larger than the
previous estimation of 700 yr. gt The initial
amount of 44Ti should be 10,000 times larger than
that estimated previously (Iyudin 1998).
Distance Effect the distance estimated here is
about 4 times larger than the previous estimation
of 200 pc. gt The initial amount of 44Ti should
be 16 times larger than that estimated previously
(Iyudin 1998).
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Possible Relation to the Point Source

• -- AX J0851.9-4617.4 --
• Distance Larger than that for the Vela SNR
  (Slane 2001 Kargaltsev 2002) .
• Age A few 103 yr (Kargaltsev 2002).

gt Consistent at least qualitatively with the
distance we estimated for Vela Jr.
AX J0851.9-4617.4
ASCA GIS 0.7-10keV
gt Consistent with the age we estimated for Vela
Jr.
Slane (2001)
It is likely that this point source is a stellar
remnant (CCO) left behind the SN explosion which
produced Vela Jr.
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Origin of TeV g-ray emission
Electronic process Hadronic process
ASCA
synchrotron
p0-decay
HESS
Near200pc
IC scattering
Parkes
synchrotron
ASCA
HESS
p0-decay
Far1 kpc
IC scattering
Parkes
Aharonian (2007)
Low magnetic field of 6 mG is required, which
is not realistic from theoretical point of view
(Aharonian 2007).
The situation of a cavity SN explosion is
required (Aharonian 2007), which is consistent
with the existence of the CCO.
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Summary

• We have measured a proper-motion in the
  northwestern rim of RX J0852.0-4622 (Vela Jr.).
  The proper-motion is measured to be 0.840.23
  yr-1, which is about only 1/7 of that expected
  for the free expansion.
• Using the measured proper-motion, the age and the
  distance are estimated to be 1700-4300 yr and at
  least 750 pc, respectively.
• 44Ti the new age and distance strongly suggest
  that the emission lines associated with 44Ti are
  not related to this remnant.
• Point Source the new age and distance are
  consistent with those for AX J0851.9-4617.4,
  supporting the idea that the point source is a
  stellar remnant of a SN explosion which produced
  Vela Jr.

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Another Age Estimation
NO3- concentration (mg ml-1)
Rood (1979) reported that dates of three nitrate
spikes in Antarctic ice core well corresponded to
arrival times of light from historical
SNe. Burgess Zuber (1999) proposed that the
unidentified spike matched that for Vela Jr.
(700 yrs ago). gt Age is determined to be 680
/- 20 yr.
AD
Kepler (1604)
Tycho (1572)
Ice Depth (m)
Vela Jr. ?
3C58 (1181)
Burgess Zuber (1999)
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Vela Jr. is NOT so Young
Expansion Index, m (R?tm), (Expansion Rate) x
(Age).m 1 (free expansion), 0.4 (Sedov), 0.25
(snowplow)
1
m1 (free expansion)
2
3
m0.4 (Sedov)
4
m0.25 (snowplow)
Vela Jr. (This work)
43001200 yr
1700440 yr
5
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Note.
Note that there is a possibility for explaining
the current low expansion rate without any
modifications of the young age of 700 yr.
Recent rapid deceleration of the shock in the
northeastern rim might be the case. But, more
straightforward interpretation is simply because
this remnant is not so young (700 yr), but
around 1700-4300 yr.
Cloud or Cavity wall
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SN1006 XMM-Newton image
http//heasarc.gsfc.nasa.gov/Images/objects/heapow
/nebulae/sn1006_xmm_small.jpg