The Slow X-Ray Expansion of the Northwestern Rim of RX J Satoru Katsuda (Osaka U. / NASA GSFC), Hiroshi Tsunemi (Osaka U.), and Koji Mori (Miyazaki U.) May 28, in Spain This talk is based on ApJ, 678, L35-L38, 2008

RX J (Vela Jr.) ROSAT all-sky survey image XMM-Newton 3 color image Outline Introduction to RX J Introduction to RX J Discovery of the SNR, 44 Ti  /X-ray line emission, a stellar remnant, non-thermal emission up to TeV  -ray Discovery of the SNR, 44 Ti  /X-ray line emission, a stellar remnant, non-thermal emission up to TeV  -ray XMM-Newton Observations and Analysis XMM-Newton Observations and Analysis Measuring the X-ray expansion of the forward shock Measuring the X-ray expansion of the forward shock Discussion Discussion Summary Summary

Discovery of RXJ (Vela Jr.) Above 1.3 keV RX J RX J 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 8x10 21 cm -2 => Near (< 1kpc) Puppis A SNR ROSAT all-sky survey keV Aschenbach (1998) Vela SNR

44 Ti Decay Line COMPTEL detected  -ray line emission from 44 Ti at the same time of the discovery of this remnant (Iyudin+ 1998). Vela Jr. was the 2 nd object, which showed 44 Ti decay line, following the Cas A SNR. 44 Ti → 44 Sc+2  → 44 Ca+   Very young (~700 yr) & very near (~200 pc)  ~90 yr  ~8 hr 44 Ti  -ray line MeV Iyudin+ (1998) X-ray hard band (Aschenbach 1998) X-ray wideband (Aschenbach 1998)

Possible Line ~ASCA SIS0 Chip~ K-shell emission line from 44 Ca was detected by the ASCA SIS0 chip (Tsunemi+ 2000). Combining the amount of 44 Ca and the observed flux of 44 Ti, 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 44 Ca K 

Possible Line ~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 the Near Distance Reanalysis of the COMPTEL data => The 44 Ti  -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 44 Ti 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 J Ti  -ray line (Iyudin+ 1998) 44 Ti  -ray line (Schonfelder+2000) 1 2 5

Central Compact Object (CCO) Slane+ (2001) ASCA GIS keV AX J Kargaltsev+ (2002) A compact object, AX J , was discovered around the center of this remnant. - Absorption: ~3x10 21 cm -2 (Slane+ 2001; Kargaltsev+ 2002) - Age: ~ a few 10 3 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 Emission Vela Jr. shows non-thermal dominated spectra from thin filaments in the NW rim. Radial profile Slane Chandra image Bamba+ 2005

TeV  -ray Emission Aharonian+ (2007) The 2 nd shell-type SNR which was spatially resolved at TeV energies, following RXJ SNR. => A key object to understand the origin (Electronic or Hadronic process?) of TeV  -ray emission. H.E.S.S TeV image

RX J (Vela Jr.) ROSAT all-sky survey image XMM-Newton 3 color image Outline Introduction to RX J Introduction to RX J Discovery of the SNR, 44 Ti  /X-ray line emission, stellar remnant, non-thermal emission up to TeV  -ray Discovery of the SNR, 44 Ti  /X-ray line emission, stellar remnant, non-thermal emission up to TeV  -ray XMM-Newton Observations and Analysis XMM-Newton Observations and Analysis Measuring the X-ray expansion of the forward shock Measuring the X-ray expansion of the forward shock Discussion Discussion Summary Summary

XMM-Newton Observations of the NW-Rim of Vela Jr. Obs. DateExp. Time 1. 04/25/ ks 2. 06/22/ ks 3. 11/01/ ks 4. 10/24/ ks - Radius: ~60’ - Age: ~700 yr Three-color XMM-Newton image of the NW rim of Vela Jr. Red:0.4-1keV Green:1-1.5 keV Blue:1.5-8 keV Mean angular velocity ~ 35”/6.5 yrs 6.5 yr ~60’

Astrometric Accuracy XMM-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 Image 5 arcmin The proper-motion can be apparently seen as a black filament from NE to SW. Hard band image (2001)Difference Image ( )

Radial Profile 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

 2 Distributions arcseconds 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 ∝ t m ), = (Expansion Rate) x (Age). m = 1 (free expansion), 0.4 (Sedov), 0.25 (snowplow)… Vela 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) ±440 yr 4300±1200 yr

Vela 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. SNRShock velocity Kepler4200 km/sec (Katsuda+2008; Vink 2008) Tycho3300 km/sec (Hughes 2000) Cas A3200 km/sec (Vink+1998; Koralesky+1998) SN km/sec (Winkler+ 2003) Vela Jr. shows non- thermal dominated spectra.

RX J (Vela Jr.) ROSAT all-sky survey image XMM-Newton 3 color image Outline Introduction to RX J Introduction to RX J Discovery of the SNR, 44 Ti  /X-ray line emission, stellar remnant, non-thermal emission up to TeV  -ray Discovery of the SNR, 44 Ti  /X-ray line emission, stellar remnant, non-thermal emission up to TeV  -ray XMM-Newton Observations and Analysis XMM-Newton Observations and Analysis Measuring the X-ray expansion of the forward shock Measuring the X-ray expansion of the forward shock Discussion Discussion Summary Summary

Probable NON Detection of the 44 Ti Line Age Effect: the newly determined age, yr, is at least 2.5 times larger than the previous estimation of 700 yr. => The initial amount of 44 Ti 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 44 Ti should be 16 times larger than that estimated previously (Iyudin+ 1998). The initial amount of 44 Ti must be at least 1.6x10 5 times larger than that estimated in the paper by Iyudin+ (1998). => The COMPTEL detection of the  -ray line at MeV seems to have no relation to Vela Jr. 44 Ti  -ray line image Iyudin+ (1998)

Possible Relation to the Point Source Slane+ (2001) ASCA GIS keV AX J AX J Distance: Larger than that for the Vela SNR (Slane+ 2001; Kargaltsev+ 2002). - Age: ~ A few 10 3 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  -ray emission Electronic process Hadronic process Far: 1 kpc Aharonian+ (2007) ASCA HESS Parkes ASCA HESS Parkes synchrotron IC scattering synchrotron  0 -decay IC scattering Near: 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

Summary We have measured a proper-motion in the northwestern rim of RX J (Vela Jr.). The proper-motion is measured to be 0.84”±0.23” yr -1, which is about only 1/7 of that expected for the free expansion. We have measured a proper-motion in the northwestern rim of RX J (Vela Jr.). The proper-motion is measured to be 0.84”±0.23” 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 yr and at least 750 pc, respectively. Using the measured proper-motion, the age and the distance are estimated to be yr and at least 750 pc, respectively. 44 Ti: the new age and distance strongly suggest that the emission lines associated with 44 Ti are not related to this remnant. 44 Ti: the new age and distance strongly suggest that the emission lines associated with 44 Ti are not related to this remnant. Point Source: the new age and distance are consistent with those for AX J , supporting the idea that the point source is a stellar remnant of a SN explosion which produced Vela Jr. Point Source: the new age and distance are consistent with those for AX J , supporting the idea that the point source is a stellar remnant of a SN explosion which produced Vela Jr.

Another Age Estimation Kepler (1604) Tycho (1572) 3C58 (1181) AD Ice Depth (m) NO 3 - concentration (  g 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). => Age is determined to be 680 +/- 20 yr. Burgess & Zuber (1999) Vela Jr. ?

Expansion Index, m (R ∝ t m ), = (Expansion Rate) x (Age). m = 1 (free expansion), 0.4 (Sedov), 0.25 (snowplow)… Vela 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) ±440 yr 4300±1200 yr

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 yr. Cloud or Cavity wall

SN1006 XMM-Newton image s/heapow/nebulae/sn1006_xmm_small.jpg