2005ApJ...631..809X

Query : 2005ApJ...631..809X

2005ApJ...631..809X - Astrophys. J., 631, 809-819 (2005/October-1)

Chandra study of X-ray point sources in the early-type galaxy NGC 4552 (M 89).

XU Y., XU H., ZHANG Z., KUNDU A., WANG Y. and WU X.-P.

Abstract (from CDS):

We present a Chandra ACIS study of the early-type galaxy NGC 4552. We detect 47 X-ray point sources, most of which are likely low-mass X-ray binaries (LMXBs), within four effective radii (Re). The brightest X-ray source coincides with the optical, UV, and radio center of the galaxy and shows variability on >1 hr timescales, indicating the possible existence of a low-luminosity active galactic nucleus (AGN). The 46 off-center sources and the unresolved point sources contribute about 29% and 20% to the total luminosity of the galaxy, respectively. We find that after correcting for the incompleteness at the low-luminosity end, the observed cumulative X-ray luminosity function (XLF) of the off-center sources is best fitted by a broken power-law model with a break at Lb=4.4+2.0–1.4x1038 ergs/s. We identified 210 globular cluster (GC) candidates in a HST WFPC2 optical image of the galaxy's central region. Of the 25 off-center LMXBs that fall within the WFPC2 field of view, 10 sources are coincident with a GC. Thus, the fraction of the GCs hosting bright LMXBs and the fraction of the LMXBs associated with GCs are 4.8% and 40%, respectively. In the V and I bands, the GCs hosting bright LMXBs are typically 1-2 mag brighter than the GCs with no detected LMXBs. There are about 1.9±0.4 times as many LMXBs in the red, metal-rich GCs as there are in the blue, metal-poor ones. We find no obvious difference between the luminosity distributions of LMXBs in GCs and in the field, but the cumulative spectrum of the LMXBs in GCs tends to be softer than that of the LMXBs in field. We detected three X-ray sources that have isotropic luminosities larger than 1039 ergs/s. Only one of these is located in the joint Chandra-HST field and is found to be associated with a GC. By studying its ACIS spectra we infer that the this may be a candidate black hole system with a mass of 15-135 M☉. One of the other sources with a luminosity brighter than 1039 ergs/s reveals temporal variations in brightness on timescales greater than 1 hr.

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Journal keyword(s): Stars: Binaries: Close - Galaxies: Elliptical and Lenticular, cD - galaxies: individual (NGC 4552 (M89)) - X-Rays: Binaries - X-Rays: Galaxies - X-Rays: Stars

Nomenclature: Table 1: [XXZ2005] NN (Nos 1-47).

Simbad objects: 64

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Number of rows : 64
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
2 BAX 028.2522-13.7387 ClG 01 53 00.40 -13 44 18.0           ~ 389 0
3 NGC 720 Sy1 01 53 00.523 -13 44 19.25   12.4   10.36   ~ 536 0
4 RX J031820.3-662911 UX? 03 18 20.00 -66 29 10.9           ~ 229 1
5 NGC 1332 GiP 03 26 17.321 -21 20 07.33   11.45   9.84   ~ 378 0
6 NGC 1399 rG 03 38 29.083 -35 27 02.67 11.05 9.74 9.59 8.12   ~ 1636 1
7 NGC 1553 GiP 04 16 10.4697802536 -55 46 48.072797400 10.76 10.10 9.40 8.74   ~ 395 2
8 NGC 1600 rG 04 31 39.858 -05 05 09.97   8.9   10.81   ~ 409 1
9 RX J0957.9+6903 ULX 09 57 53.290 +69 03 48.20           ~ 246 4
10 NGC 4365 GiG 12 24 28.228 +07 19 03.07   11.5       ~ 871 0
11 M 85 GiP 12 25 24.053 +18 11 27.89   10.2       ~ 678 0
12 M 49 Sy2 12 29 46.8 +08 00 01   13.21 12.17     ~ 2174 2
13 NAME Virgo Cluster ClG 12 30 47.8 +12 23 07           ~ 7107 0
14 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7815 3
15 [XXZ2005] 42 XB* 12 35 33.69 +12 33 37.5           ~ 2 0
16 [XXZ2005] 34 XB* 12 35 35.25 +12 33 07.4           ~ 2 0
17 [XXZ2005] 33 XB* 12 35 36.03 +12 33 33.7           ~ 2 0
18 [XXZ2005] 35 XB* 12 35 36.11 +12 32 38.9           ~ 2 0
19 [XXZ2005] 28 XB* 12 35 36.90 +12 33 08.0           ~ 2 0
20 [XXZ2005] 29 XB* 12 35 36.91 +12 33 05.6           ~ 2 0
21 CXOU J123537.3+123322 XB* 12 35 37.33 +12 33 22.2           ~ 2 0
22 [XXZ2005] 16 XB* 12 35 38.00 +12 33 37.4           ~ 2 0
23 CXOU J123538.0+123328 XB* 12 35 38.0417 +12 33 28.343           ~ 3 0
24 CXOU J123538.0+123326 XB* 12 35 38.06 +12 33 25.6           ~ 2 0
25 [XXZ2005] 38 XB* 12 35 38.18 +12 32 03.3           ~ 2 0
26 [XXZ2005] 17 XB* 12 35 38.24 +12 33 02.8           ~ 2 0
27 [XXZ2005] 10 XB* 12 35 38.32 +12 33 18.1           ~ 2 0
28 [XXZ2005] 40 XB* 12 35 38.49 +12 31 56.5           ~ 2 0
29 [XXZ2005] 45 XB* 12 35 39.23 +12 31 42.6           ~ 2 0
30 [XXZ2005] 8 XB* 12 35 39.37 +12 33 41.9           ~ 2 0
31 [XXZ2005] 11 XB* 12 35 39.69 +12 33 00.4           ~ 2 0
32 [XXZ2005] 3 XB* 12 35 39.69 +12 33 18.1           ~ 2 0
33 [XXZ2005] 36 XB* 12 35 39.69 +12 34 33.1           ~ 2 0
34 M 89 Sy2 12 35 39.80733343 +12 33 22.8308657 11.29 10.73 9.75     ~ 1037 2
35 [XXZ2005] 1 X 12 35 39.82 +12 33 23.0           ~ 1 0
36 [XXZ2005] 2 XB* 12 35 39.92 +12 33 18.0           ~ 2 0
37 [XXZ2005] 13 XB* 12 35 39.93 +12 33 48.1           ~ 2 0
38 [XXZ2005] 21 XB* 12 35 40.16 +12 33 58.1           ~ 2 0
39 [XXZ2005] 19 XB* 12 35 40.27 +12 32 49.1           ~ 2 0
40 [XXZ2005] 4 XB* 12 35 40.30 +12 33 10.7           ~ 2 0
41 [XXZ2005] 20 XB* 12 35 40.47 +12 33 57.1           ~ 2 0
42 CXOU J123540.4+123250 XB* 12 35 40.50 +12 32 50.5           ~ 2 0
43 [XXZ2005] 5 XB* 12 35 40.53 +12 33 33.3           ~ 2 0
44 [XXZ2005] 6 XB* 12 35 40.62 +12 33 12.2           ~ 2 0
45 [XXZ2005] 9 XB* 12 35 40.63 +12 33 40.5           ~ 2 0
46 [XXZ2005] 12 XB* 12 35 40.76 +12 33 02.8           ~ 2 0
47 [XXZ2005] 7 XB* 12 35 40.90 +12 33 17.1           ~ 2 0
48 [XXZ2005] 23 XB* 12 35 40.99 +12 32 48.4           ~ 2 0
49 2XMM J123541.1+123451 XB* 12 35 41.2122950784 +12 34 51.333937464           ~ 4 0
50 [XXZ2005] 27 XB* 12 35 41.30 +12 33 59.6           ~ 2 0
51 [XXZ2005] 24 XB* 12 35 41.37 +12 32 51.1           ~ 2 0
52 [XXZ2005] 46 XB* 12 35 41.53 +12 31 39.6           ~ 2 0
53 CXOU J123541.5+123251 XB* 12 35 41.61 +12 32 51.1           ~ 2 0
54 [XXZ2005] 32 XB* 12 35 41.76 +12 32 35.7           ~ 2 0
55 [XXZ2005] 25 XB* 12 35 42.17 +12 33 00.5           ~ 2 0
56 [XXZ2005] 30 XB* 12 35 42.39 +12 32 54.1           ~ 2 0
57 [XXZ2005] 44 XB* 12 35 43.19 +12 34 50.0           ~ 2 0
58 [XXZ2005] 31 XB* 12 35 43.40 +12 33 10.0           ~ 2 0
59 [XXZ2005] 37 XB* 12 35 44.82 +12 33 40.8           ~ 3 0
60 [XXZ2005] 39 XB* 12 35 45.69 +12 33 22.4           ~ 2 0
61 [XXZ2005] 41 XB* 12 35 45.77 +12 33 02.4           ~ 3 0
62 [XXZ2005] 47 XB* 12 35 46.63 +12 32 40.1           ~ 2 0
63 M 60 GiC 12 43 39.9708251934 +11 33 09.688174067   10.3       ~ 1395 1
64 NGC 4697 GiG 12 48 35.8981498824 -05 48 02.482374564   10.97   9.83   ~ 895 0

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