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

The Slow X-Ray Expansion The Slow X-Ray Expansion of the Northwestern Rim of of the Northwestern Rim of

RX J0852.0-4622RX J0852.0-4622

Satoru Katsuda (Osaka U. / NASA GSFC), Satoru Katsuda (Osaka U. / NASA GSFC), Hiroshi Tsunemi (Osaka U.), and Hiroshi Tsunemi (Osaka U.), and

Koji Mori (Miyazaki U.)Koji Mori (Miyazaki U.)

May 28, 2008 @Granada in SpainMay 28, 2008 @Granada in Spain

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

RX J0852.0-4622 (Vela Jr.) ROSAT all-sky survey image XMM-Newton 3 color image

OutlineOutline Introduction to RX J0852.0-4622Introduction to RX J0852.0-4622

Discovery of the SNR, Discovery of the SNR, 4444Ti Ti /X-ray line emission, a /X-ray line emission, a stellar remnant, non-thermal emission up to TeV stellar remnant, non-thermal emission up to TeV -ray-ray

XMM-Newton Observations and AnalysisXMM-Newton Observations and Analysis Measuring the X-ray expansion of the forward shockMeasuring the X-ray expansion of the forward shock

DiscussionDiscussionSummarySummary

Discovery of RXJ0852.0-4622 (Vela Jr.)Discovery of RXJ0852.0-4622 (Vela Jr.)

Above 1.3 keV

RX J0852-4622

RX J0852.0-4622 was discovered in the southeastern corner of the Vela SNR ten years ago (Aschenbach 1998).- High energy X-ray emission => Young (<1500 yr)- Low absorption less than 8x1021 cm-2 => Near (< 1kpc)

Puppis A SNRROSAT all-sky survey

0.1-2.4 keV

Aschenbach (1998)

Vela SNR

4444Ti Decay LineTi Decay LineCOMPTEL detected -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 → 44Sc+2 → 44Ca+

Very young (~700 yr) & very near (~200 pc)

~90 yr ~8 hr44Ti -ray line image @1.157 MeV Iyudin+ (1998)

X-ray hard band(Aschenbach 1998)X-ray wideband

(Aschenbach 1998)

Possible LinePossible Line Feature @~4keV Feature @~4keV ~ASCA SIS0 Chip~~ASCA SIS0 Chip~

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.

ROSAT image of Vela Jr.

ASCA SIS0 spectrum of the northwestern rim

Tsunemi+ (2000)

ASCA FOV

He-like 44Ca K

Possible Line Feature @~4keV Possible Line Feature @~4keV ~XMM-Newton & Chandra~~XMM-Newton & Chandra~

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.

Iyudin+ (2005)

XMM-Newton PN spectrum of the NW rim

Chandra ACIS spectrum of the NW rim

Bamba+ (2005)

Line feature (from Ti/Sc)

Line feature

Doubts for the Young Age and Doubts for the Young Age and the Near Distance the Near Distance

Reanalysis of the COMPTEL data => The 44Ti -ray emission was only 2-4 level (Schonfelder+ 2000). No line feature around 4 keV by ASCA except for SIS0 (Slane+ 2001). =>Are emission lines related to 44Ti really significant? Also, is this remnant really young?Higher absorption than that for the Vela SNR (Slane+ 2001). =>Is this remnant really near?

ASCA GIS spectra

Slane+ (2001)

RX J085244Ti -ray line(Iyudin+ 1998)

44Ti -ray line(Schonfelder+2000)

1 2 5

Central Compact Object (CCO)Central Compact Object (CCO)

Slane+ (2001)

ASCA GIS 0.7-10keV

AX J0852.0-4622

Kargaltsev+ (2002)

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)=>Is this point source a stellar remnant of Vela Jr.?

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

Non-Thermal EmissionNon-Thermal Emission

Vela Jr. shows non-thermal dominated spectra from thin filaments in the NW rim.

Radial profile

Slane+ 2001

Chandra imageBamba+ 2005

TeV TeV -ray Emission-ray Emission

Aharonian+ (2007)

The 2nd shell-type SNR which was spatially resolved at TeV energies, following RXJ1713.7-3946 SNR.

=> A key object to understand the origin (Electronic or Hadronic process?) of TeV -ray emission.

H.E.S.S. 0.5-20 TeV image



Discovery of the SNR, Discovery of the SNR, 4444Ti Ti /X-ray line emission, /X-ray line emission, stellar remnant, non-thermal emission up to TeV stellar remnant, non-thermal emission up to TeV -ray-ray



XMM-Newton Observations of XMM-Newton Observations of the NW-Rim of Vela Jr.the NW-Rim of Vela Jr.

Obs. Date Exp. Time

1. 04/25/2001 31 ks2. 06/22/2003 26 ks3. 11/01/2005 64 ks4. 10/24/2007 63 ks

- 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

6.5 yr

~60’

Astrometric AccuracyAstrometric AccuracyXMM-Newton (Kirsch 2007)absolute astrometric accuracy: ~2”

We focused on four point sources in the FOV. All the sources are detected within the 2”-circles in all the observations.

=>2” as a conservative systematic error

Hard band (1.5-8 keV) image

5 arcmin

Difference ImageDifference Image

5 arcmin

The proper-motion can be apparently seen as a black filament from NE to SW.

Hard band image (2001) Difference Image (2001-2007)

Radial ProfileRadial Profile

n

k klk

kxlkxl

122

21

2212

)()(

)()(

Quantitative shift estimation

l : shift parameter, k: bin

We shift the 2001 profile and compare it with 2003, 2005, or 2007 profiles.

=> search for l-value which results in minimum.

Proper Motion: ~5”/6.5 yr

X-ray image

22 Distributions Distributions

2001-20032001-20052001-2007

6arcseconds

The proper motion => 0.84”±0.23” yr-1.The expansion rate => 0.023±0.006% (=0.84”/60’) yr-1.

Expansion Index, m (R∝ tm), = (Expansion Rate) x (Age).m = 1 (free expansion), 0.4 (Sedov), 0.25 (snowplow)…

Vela Jr. is NOT so YoungVela Jr. is NOT so Young

5☆ : Cygnus Loop (Blair+ 2005)4☆ : SN 1006 (Moffett+ 1993)

1☆ : Cas A (e.g., Vink+ 1998)2☆ : Kepler (Katsuda+ 2008; Vink 2008) 3☆ : Tycho (Hughes 2000)

m=1 (free expansion)

m=0.25 (snowplow)

Vela Jr. (This work)

m=0.4 (Sedov)

1

23

4

5

1700±440 yr 4300±1200 yr

Vela Jr. is NOT so CloseVela Jr. is NOT so Close

Non-thermal synchrotron radiation in the X-ray band requires a high shock speed of 3000 km/sec (e.g., Uchiyama+ 2003).

Distance >750 (v/3000 km sec-1)(m/0.84” yr-1) pc.

SNR Shock velocity

Kepler 4200 km/sec (Katsuda+2008; Vink 2008)

Tycho 3300 km/sec (Hughes 2000)

Cas A 3200 km/sec (Vink+1998; Koralesky+1998)

SN 1006 3100 km/sec (Winkler+ 2003)

Vela Jr. shows non-thermal dominated spectra.



Discovery of the SNR, Discovery of the SNR, 4444Ti Ti /X-ray line emission, /X-ray line emission, stellar remnant, non-thermal emission up to TeV stellar remnant, non-thermal emission up to TeV -ray-ray



Probable NON Detection of the Probable NON Detection of the 4444Ti LineTi Line

Age Effect: the newly determined age, 1700-4300 yr, is at least 2.5 times larger than the previous estimation of 700 yr. => 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. => The initial amount of 44Ti should be 16 times larger than that estimated previously (Iyudin+ 1998).

The initial amount of 44Ti must be at least 1.6x105 times larger than that estimated in the paper by Iyudin+ (1998). => The COMPTEL detection of the -ray line at 1.157 MeV seems to have no relation to Vela Jr.

44Ti -ray line image Iyudin+ (1998)

Possible Relation to the Point SourcePossible Relation to the Point Source

Slane+ (2001)

ASCA GIS 0.7-10keV

AX J0851.9-4617.4

-- AX J0851.9-4617.4 --- Distance: Larger than that for the Vela SNR (Slane+ 2001; Kargaltsev+ 2002) .

- Age: ~ A few 103 yr (Kargaltsev+ 2002).

=> Consistent at least qualitatively with the distance we estimated for Vela Jr.

=> Consistent with the age we estimated for Vela Jr.

It is likely that this point source is a stellar remnant (CCO) left behind the SN explosion which produced Vela Jr.

Origin of TeV Origin of TeV -ray emission-ray emissionElectronic process Hadronic process

Far:1 kpc

Aharonian+ (2007)

ASCAHESS

Parkes

ASCA HESS

Parkes

synchrotron

IC scattering

synchrotron 0-decay

IC scatteringNear:200pc

Low magnetic field of ~ 6 G 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.

0-decay

SummarySummary We have measured a proper-motion in the northwestern rim of We have measured a proper-motion in the northwestern rim of

RX J0852.0-4622 (Vela Jr.). The proper-motion is measured to RX J0852.0-4622 (Vela Jr.). The proper-motion is measured to be be 0.84”±0.23” yr0.84”±0.23” yr-1-1, which is about , which is about only 1/7 only 1/7 of that expected for of that expected for the free expansion.the free expansion.

Using the measured proper-motion, the age and the distance are Using the measured proper-motion, the age and the distance are estimated to be estimated to be 1700-4300 yr1700-4300 yr and and at least 750 pcat least 750 pc, respectively., respectively.

4444Ti:Ti: the new age and distance strongly suggest that the the new age and distance strongly suggest that the emission lines associated with emission lines associated with 4444Ti are Ti are not relatednot related to this to this remnant. remnant.

Point Source:Point Source: the new age and distance are consistent with the new age and distance are consistent with those for AX J0851.9-4617.4, supporting the idea that those for AX J0851.9-4617.4, supporting the idea that the point the point source is a stellar remnant source is a stellar remnant of a SN explosion which produced of a SN explosion which produced Vela Jr.Vela Jr.

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

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