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

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 @Granada in Spain. This talk is based on ApJ, 678, L35-L38, 2008. Outline. Introduction to RX J0852.0-4622

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

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

  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 => Young (<1500 yr) - Low absorption less than 8x1021 cm-2 => Near (< 1kpc)

  4. X-ray wideband X-ray hard band 44Ti Decay Line (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 → 44Sc+2g→ 44Ca+g • Very young (~700 yr)& very near (~200 pc) t~90 yr t~8 hr 44Ti g-ray line image @1.157 MeV Iyudin+ (1998)

  5. Possible LineFeature @~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.

  6. Possible Line Feature @~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.

  7. Doubts for the Young Age and the Near Distance Reanalysis of the COMPTEL data => 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). =>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? RX J0852 44Ti g-ray line(Schonfelder+2000) 44Ti g-ray line(Iyudin+ 1998) ASCA GIS spectra 1 2 5 Slane+ (2001)

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

  9. Non-Thermal Emission Radial profile Chandra imageBamba+ 2005 Vela Jr. shows non-thermal dominated spectra from thin filaments in the NW rim. Slane+ 2001

  10. TeV g-ray Emission 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 g-ray emission. H.E.S.S. 0.5-20 TeV image Aharonian+ (2007)

  11. 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

  12. 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

  13. 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. =>2” as a conservative systematic error 5 arcmin

  14. 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.

  15. X-ray image Radial Profile 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. => search for l-value which results in c2minimum.

  16. c2 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.

  17. 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 m=1 (free expansion) 1☆: Cas A (e.g., Vink+ 1998) 2 2☆: Kepler (Katsuda+ 2008; Vink 2008) 3 3☆: Tycho (Hughes 2000) m=0.4 (Sedov) 4☆: SN 1006 (Moffett+ 1993) 5☆: Cygnus Loop (Blair+ 2005) 4 m=0.25 (snowplow) Vela Jr. (This work) 4300±1200 yr 1700±440 yr 5

  18. 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 >750 (v/3000 km sec-1)(m/0.84” yr-1) pc.

  19. 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

  20. Probable NON Detection of the 44Ti Line The initial amount of 44Ti must be at least 1.6x105 times largerthan that estimated in the paper by Iyudin+ (1998). => 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. => 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).

  21. 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). => Consistent at least qualitatively with the distance we estimated for Vela Jr. AX J0851.9-4617.4 ASCA GIS 0.7-10keV => 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.

  22. Origin of TeV g-ray emission Electronic process Hadronic process ASCA synchrotron p0-decay HESS Near:200pc IC scattering Parkes synchrotron ASCA HESS p0-decay Far:1 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.

  23. 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 0.84”±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 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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