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A Candidate Neutron Star & Its Association with Sgr A East

High Energy Phenomena in the Galactic Center, Paris, France, June 15, 2005. A Candidate Neutron Star & Its Association with Sgr A East. Sangwook Park. Department of Astronomy & Astrophysics. The Pennsylvania State University. Collaborators: Michael Muno (UCLA) Frederick Baganoff (MIT)

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A Candidate Neutron Star & Its Association with Sgr A East

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  1. High Energy Phenomena in the Galactic Center, Paris, France, June 15, 2005 A Candidate Neutron Star& Its Association with Sgr A East Sangwook Park Department of Astronomy & Astrophysics The Pennsylvania State University Collaborators: Michael Muno (UCLA) Frederick Baganoff (MIT) Yoshitomo Maeda (ISAS) Mark Morris (UCLA) George Chartas (Penn State) Divas Sanwal (Penn State) David Burrows (Penn State) Gordon Garmire (Penn State)

  2. Sgr A East: -Nonthermal radio shell -X-ray detected by ROSAT, ASCA, Beppo-SAX -Chandra: Maeda et al. (2002) MM SNR, kT=2 keV, CIE E ~ 2 x 1049 ergs, M ~ 2 Msun Fe-rich center: He-like Fe line Abund ratios => Type II SN -XMM: Sakano et al. (2004) SNR, central He- & H-like Fe => kT=1 keV & 4 keV, CIE Abund pattern =>Type Ia or II? “Neutral” Fe (6.4 keV) ACIS-I: Sgr A* 1999-9 ~ 2002-6: 7 GTO & 5 GO obs => ~590 ks Spatially-resolved spectroscopy with high photon statistics - to test “Chandra vs XMM” - to test SN type Core-collapse SN: potential NS => CXOGC J174545.5-285829 (Muno et al. 2003) Is CXOGC J174545.5-285829 a NS associated with SNR Sgr A East? Introduction

  3. 3-Color & Fe EW images Park et al. 2005, ApJ, in press He-like Fe XXV (E ~ 6.6 keV) Ar Hea (3.1 keV) Ca Hea (3.9 keV) Red: 1.5-4.5 keV Green: 4.5-6.0 keV Blue: 6.0-8.0 keV

  4. Sgr A East: Spectra & Fe Mass Fe ejecta mass: EM => nFe ~ 0.12 f-0.5 cm-3 MFe < 0.15 - 0.27 Msun Type Ia: MFe ~ 0.5 – 0.8 Msun(Nomoto et al. 1997a) Type II: MFe ~ 0.15 Msun for Mstar = 13 – 15 Msun MFe ~ 0.05 – 0.08 Msun for Mstar = 18 – 70 Msun (Nomoto et al. 1997b) => Sgr A East is likely from a core-collapse SN. 1.5-8 keV Plume kT=1.3 keV Fe=1 solar Center kT=1.1 keV + 5.3 keV Fe=5.8 solar

  5. Neutron Star Candidate: “the Cannonball” N The cannonball High velocity NS? - Tail: ~0.1 pc physical size - ~2’ from “center”:v ~ (455-912)/sin km s-1 for SNR age ~ 5000 – 10000 yr - Mach number ~ 2.2: v ~ 880 km s-1 for ISM kT ~ 1 keV - Pressure balance: PPWN (Edot/4cR2) = Ptherm (2nekT) = Pram (v2) where  = 2.36-0.021 Edot-0.5(Gotthelf 2003), v ~ 550 km s-1 =>Three velocities from independent estimates are consistent. =>Also consistent with typical Galactic high-velocity pulsars (e.g. Cordes & Chernoff 1998). E =1.6 Lx=3x1033 ergs s-1 No varibility detected S N

  6. Summary • CXOGC J174545.5-285829 (the Cannonball): A High-V NS? - Cometary morphology - X-ray spectrum: Hard, nonthermal continuum,= 1.6 - X-ray luminosity Lx = 3 x 1033 ergs s-1 - No variability • Associated with Sgr A East? - Proximity to Sgr A East: estimated velocities are reasonable - Positional coincidence at the “tip” of Sgr A East Plume - Cometary tail extending toward Sgr A East - Sgr A East is likely a core-collapse SNR: MFe < 0.27 Msun However, no evidence for a “pulsar”: - XMM/PN places an upper limit of ~40% on the pulsed fraction at P > 147 ms. => High time-resolution, high-sensitivity X-ray/radio observations are necessary.

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