Identification of X-ray Point Sources and Study on the Nature of 62 X-ray Globular Cluster Candidates in M31 Zhou Fan, Jun Ma, Xu Zhou, Jiansheng Chen, Zhaoji Jiang, Zhenyu Wu

Our work contains 2 parts: 1. Identify the 8 unknown X-ray Sources. 2.Study the optical nature of 62 GC X-ray sources.

The Data of X-ray Point Sources in M31 1.Trinchieri & Fabbiano(1991) presented the positions of 108 Einstein X-ray sources 2.Primini, Forman & Jones(1993) listed the positions of 86 ROSAT HRI X-ray sources. 3.Supper et al. (2001) 2 nd ROSAT detection of M31, 7 GC X-ray sources. 4.Kong et al. (2002) (Chandra ACIS)204 X-ray point sources. 5.Kaaret (2002) (Chandra HRC)143 X-ray point sources. 6.Williams et al. (2004) (Chandra HRC)166 X-ray point sources. 7.Trudolyubov & Priedhorsky (2004), (XMM-Newton & Chandra ) 43 GC X-ray sources.

The BATC Optical Observation of M31  Using 60/90cm f/3 Schmidt telescope in XINGLONG Station of NAOC, CAS.  2048 X 2048(pixels) CCD.  Field of view ~ 58’X 58’, 1 pixel ~ 1.67”.  Using 13 intermediate-band filters (BATC03 - BATC15) covering from 4,000~10,000 Å.  The observation of M31 was from Nov. 15th, 1995 to Dec. 16th, 1999.

Obtained 8 new X-ray sources  We compared the BATC data and the X-ray data of M31 in 3 pixels(~5”) and found 8 new X-ray sources unidentified.8

Identification of 8 New GC X-ray Sources  Using the 49 GC X-ray sources’ SEDs as templates, we compared them with the 8 SEDs. Combined the FWHMs, we have identified 4 new GC X-ray sources.SEDsFWHMs  Criterion: χ 2 10%) & FWHM source > FWHM star 4 new GC X-ray sources.

49 GC X-ray sources (circles) and 4 new GC X-ray sources (boxes) and 9 are out the BATC M31 Field.

V distribution( 58~353 ) (KMM fit) KMM test: the distribution is bimodal with peaks at and 17.89, and p value ~ KS test: D max = ， P=4.829E-06

B-V distribution( 58~353 ) KS test: D max = ， P=0.068

Color (B-V) ~ V(58)

The Correlation between L X (0.3-10keV) and L opt (41) Log (L /10 35 ergs -1 ) = a V + b a = 0.26± 0.11; b = 6.17± 1.76, and the linear correlation coefficient r = 0.36 at the confidence level of 98.0%.

Thank you !