Vela Jr. SNR
Transcript Vela Jr. SNR
The Slow X-Ray Expansion of
the Northwestern Rim of Vela Jr.
Satoru Katsuda (1, 2), Hiroshi Tsunemi (1), & Koji Mori (3)
(1. Osaka U.; 2. NASA/GSFC; 3. Miyazaki U.)
Vela Jr. NW rim
This talk is based on ApJ, 678, L35 (2008)
Vela Jr. SNR
H.E.S.S. 0.5-20 TeV
ROSAT all-sky survey
Discovered by ROSAT (Aschenbach 1998).
High energy X-rays ⇒ Young(<1500yr)
SN Type ：Core-collapse (?)
A possible candidate of a neutron star around the
center of the SNR (Slane+2001; Kargaltsev+2002).
But, the age (a few 1000 yr) and the distance
(>~1kpc) are not consistent with those of Vela Jr.
⇒ need confirmation of the relation
ASCA GIS image
X-ray hard band
COMPTEL detected 44Ti
decay g-ray line (Iyudin+
1998), making Vela Jr.
the 2nd object from which
44Ti line was detected
(1st was Cas A).
44Ti → 44Sc+2g → 44Ca+g
g-ray line image @1.157 MeV
Very young (~700 yr)
Very near (~200 pc)
Detection of K Lines from Ca (Sc)
ROSAT image of
He-like 44Ca Ka
The age estimated from the amount of 44Ca and 44Ti is ~1000 yr
Doubt for the Distance (and Age)
(Duncan & Green 2000)
Duncan & Green (2000)
If d = 200 pc
⇒ Very unusual
If d = 1 kpc
Radio surface brightness
4.85 GHz Radio Image
Doubts for Age and Distance
~g- and X-ray Observations~
g-ray line images
Result in 2000
Result in 1998
ASCA GIS spectra
Doubts for Age：
- Re-analysis of COMPTEL data
showed only 2 s significance of
the 44Ti decay line (Schonfelder+
- ASCA SIS1 did not detect the
line feature around 4 keV (Slane+
⇒Is the detection of 44Ti true?
⇒Is Vela Jr. so young?
Doubts for Distance：
The interstellar absorption for Vela
Jr. is 10 times larger than that for
the Vela SNR (Slane+2001)
⇒Is Vela Jr. so close?
Measure the expansion rate of Vela Jr.
The first expansion measurement for this
Estimate the age and the distance based
on the expansion rate.
the relation between Vela Jr. and the possible
candidate of the neutron star.
the detection of emission lines related 44Ti.
XMM-Newton Observations of Vela Jr.
6.5 yr 2. 06/22/2003
Mean velocity ~ 35”/6.5 yrs
Green: 1-1.5 keV
XMM hard band (1.5-8 keV) image
Absolute position accuracy
of XMM-Newton is ~2”
We investigated the
positions of 4 point sources
in each observation.
⇒We confirmed that all
sources are detected within
⇒We take 2” as a systematic
Hard band image (2001)
Difference Image (2001-2007)
The motion of the shock can be seen as a black filament.
Quantitative shift estimation
x1 (k l ) x2 (k )
s 12 (k l ) s 22 (k )
l : shift parameter, k: bin
Shift the 2001 profile, and
compare it with 2003, 2005, or
⇒Search for the best-shift
position which minimizes the 2
⇒ 0.84”±0.23” yr-1.
⇒ 0.023±0.006% (=0.84”/60’) yr-1.
~Comparison with other SNRs~
Vela Jr. : ~1000–3000 年
1☆: Cas A (e.g., Vink+ 1998)
2☆: Kepler (This work; Vink 2008)
3☆: Tycho (Reynoso+ 1997; This work)
4☆: SN 1006 (Moffett+ 1993; This work)
5☆: Cygnus Loop (Blair+ 2005)
Estimation of the Distance
In general, nonthermally-dominated shocks have high
shock velocities of >3000 km/sec (e.g., Uchiyama+ 2003).
SN1006 (NE rim)
D >~750 (v/3000 km sec-1)(μ/0”.84 yr-1) pc.
Relation between Vela Jr. and NS
－ AX J0851.9-4617.4 －
- Age: ~ A few 103 yr (Kargaltsev+
⇒Consistent with the age of Vela
Jr. estimated here (1000–3000 yr)
ASCA GIS 0.7-10keV
- Distance: Farther than the Vela
SNR (Slane+ 2001; Kargaltsev+
⇒ Consistent with the distance of
Vela Jr. estimated here.
The NS candidate is strongly suggested to
be the stellar remnant of Vela Jr. SNR.
On the Detection of 44Ti Decay Line
g-ray line image
Based on the newly estimated age
and distance, the initial amount of
44Ti is calculated to be ~solar mass
(if we believe the detection by
⇒Probably, the g-ray emission
detected by COMPTEL has no
relation to Vela Jr.
Age effect: The new age (1000–3000 yr) is about twice that of
680 yr. Since the 44Ti decays exponentially with time, the
initial amount of 44Ti increases by 4000 times of that estimated
Distance effect: The new distance is at least 4 larger than that
estimated previously.⇒The amount of 44Ti increases 16 times.
We, for the first time, measured the expansion of Vela Jr.
with XMM-Newton. We found that the expansion rate is
0.84”±0.23” yr-1, which is only1/7of the free expansion.
The relation between expansion index and the age of
SNRs indicates that the age and the distance of Vela Jr.
are ~1000–3000 yr and >~750 pc, respectively.
Neutron star: The newly estimated age and distance are
consistent with those of the NS candidate.
⇒The NS candidate is likely the very NS left behind the
SN explosion which produced Vela Jr.
44Ti: The newly estimated age and distance indicates no
detection of 44Ti from Vela Jr.
⇒Probably, the emission line from 44Ti detected by
Iyudin+1998 is not related to Vela Jr.