Collaborators: Michael Muno (UCLA) Frederick Baganoff (MIT) Yoshitomo Maeda (ISAS) Mark Morris (UCLA) George Chartas (Penn State) Divas Sanwal (Penn State)

Collaborators:Collaborators:Michael Muno (UCLA)Michael Muno (UCLA)

Frederick Baganoff (MIT)Frederick Baganoff (MIT)

Yoshitomo Maeda (ISAS)Yoshitomo Maeda (ISAS)

Mark Morris (UCLA)Mark Morris (UCLA)

George Chartas (Penn State)George Chartas (Penn State)

Divas Sanwal (Penn State)Divas Sanwal (Penn State)

David Burrows (Penn State)David Burrows (Penn State)

Gordon Garmire (Penn State) Gordon Garmire (Penn State)

A Candidate Neutron StarA Candidate Neutron Star & Its & Its Association with Association with Sgr A EastSgr A East

High Energy Phenomena in the Galactic Center, High Energy Phenomena in the Galactic Center, Paris, France, June 15, 2005Paris, France, June 15, 2005

Sangwook ParkSangwook Park

Department of Astronomy & AstrophysicsDepartment of Astronomy & AstrophysicsThe Pennsylvania State UniversityThe Pennsylvania State University

IntroductionIntroduction

• Sgr A East: Sgr A East: -Nonthermal radio shell-Nonthermal radio shell

-X-ray detected by-X-ray detected byROSAT, ASCA, Beppo-ROSAT, ASCA, Beppo-

SAXSAX -Chandra:-Chandra: Maeda et al. (2002) Maeda et al. (2002) MM SNR, MM SNR, kT=2 keV, CIEkT=2 keV, CIE E ~ 2 x 10E ~ 2 x 104949 ergs, M ~ 2 M ergs, M ~ 2 Msunsun

Fe-rich center: He-like Fe lineFe-rich center: He-like Fe line Abund ratios =>Abund ratios => Type II SN Type II SN -XMM-XMM: Sakano et al. (2004): Sakano et al. (2004) SNR, central SNR, central He- & H-like FeHe- & H-like Fe => => kT=1 keV & 4 keV, CIEkT=1 keV & 4 keV, CIE Abund pattern =>Abund pattern =>Type Ia or Type Ia or

II?II? ““Neutral” Fe (6.4 keV)Neutral” Fe (6.4 keV)

• ACIS-I: Sgr A*ACIS-I: Sgr A*• 1999-9 ~ 2002-6: 1999-9 ~ 2002-6: 7 GTO & 5 GO obs 7 GTO & 5 GO obs => => ~590 ks~590 ks• Spatially-resolved Spatially-resolved

spectroscopyspectroscopy with high photon statisticswith high photon statistics - to test - to test “Chandra vs XMM”“Chandra vs XMM” - to test - to test SN typeSN type • Core-collapse SN: potential Core-collapse SN: potential NSNS => => CXOGC J174545.5-CXOGC J174545.5-

285829285829 (Muno et al. 2003)(Muno et al. 2003)• Is CXOGC J174545.5-285829Is CXOGC J174545.5-285829 a NS associated with SNR Sgr a NS associated with SNR Sgr

A East?A East?

3-Color & Fe EW images3-Color & Fe EW images

Red: 1.5-4.5 keVGreen: 4.5-6.0 keVBlue: 6.0-8.0 keV

He-like Fe XXV (E ~ 6.6 keV)Ar He (3.1 keV)

Ca He (3.9 keV)

Park et al. 2005, ApJ, in pressPark et al. 2005, ApJ, in press

Sgr A East: Spectra & Fe MassSgr A East: Spectra & Fe Mass

1.5-8 keVPlume

Center

kT=1.1 keV + 5.3 keVFe=5.8 solar

kT=1.3 keVFe=1 solar

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.

Neutron Star Candidate: “the Neutron Star Candidate: “the Cannonball”Cannonball”

N

E

NS

=1.6Lx=3x1033 ergs s-1

No varibility detected

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/) = 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).

The cannonballThe cannonball

SummarySummary

• CXOGC J174545.5-285829 (the Cannonball)CXOGC J174545.5-285829 (the Cannonball): : A High-V NS?A High-V NS? - - CometaryCometary morphology morphology - X-ray spectrum: - X-ray spectrum: Hard, nonthermal continuum,Hard, nonthermal continuum, = 1.6= 1.6 - X-ray luminosity - X-ray luminosity LLxx = 3 x 10 = 3 x 103333 ergs s ergs s-1-1

- - No variabilityNo variability• Associated with Sgr A East?Associated with Sgr A East? - - ProximityProximity to Sgr A East: estimated velocities are reasonable to Sgr A East: estimated velocities are reasonable - Positional coincidence - Positional coincidence at the “tip” of Sgr A East Plumeat the “tip” of Sgr A East Plume - Cometary - Cometary tail extending toward Sgr A Easttail extending toward Sgr A East

- Sgr A East is likely - Sgr A East is likely a core-collapse SNR: a core-collapse SNR: MMFeFe < 0.27 M < 0.27 Msunsun

However, However, no evidence for a “pulsar”:no evidence for a “pulsar”: - XMM/PN places an - XMM/PN places an upper limit of upper limit of ~40~40% on the pulsed fraction% on the pulsed fraction at at P > 147 msP > 147 ms.. => => High time-resolution, high-sensitivity X-ray/radioHigh time-resolution, high-sensitivity X-ray/radio observations are necessary.observations are necessary.