2014ApJ...789...13B

Query : 2014ApJ...789...13B

2014ApJ...789...13B - Astrophys. J., 789, 13 (2014/July-1)

Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters.

BULBUL E., MARKEVITCH M., FOSTER A., SMITH R.K., LOEWENSTEIN M. and RANDALL S.W.

Abstract (from CDS):

We detect a weak unidentified emission line at E = (3.55-3.57)±0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN "all others" spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50-110 eV of several known lines. The detection is at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with ms= 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar XVII dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10-20. Confirmation with Astro-H will be critical to determine the nature of this new line.

Abstract Copyright: ∼

Journal keyword(s): dark matter - elementary particles - line: identification - neutrinos - X-rays: galaxies: clusters

Simbad objects: 82

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Number of rows : 82
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 ACO 2811 ClG 00 42 08.82 -28 32 08.8           ~ 66 0
2 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12663 1
3 ACO 209 ClG 01 31 52.9 -13 36 53           ~ 295 0
4 ACO 2941 ClG 01 45 03.60 -53 01 23.4           ~ 53 0
5 ACO 267 ClG 01 52 43.016 +00 59 58.90           ~ 230 0
6 ACO 262 ClG 01 52 50.4 +36 08 46           ~ 699 1
7 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1746 1
8 ACO 383 ClG 02 48 03.3915 -03 31 45.228           ~ 359 0
9 2A 0251+413 ClG 02 54 32.2 +41 35 10           ~ 315 1
10 ACO 3112 ClG 03 17 52.4 -44 14 35           ~ 311 1
11 ACO 426 ClG 03 19 47.2 +41 30 47           ~ 2265 1
12 ACO 478 ClG 04 13 20.7 +10 28 35           ~ 502 0
13 ACO 496 ClG 04 33 38.8 -13 15 59           ~ 694 2
14 ACO 520 ClG 04 54 10.1 +02 55 38           ~ 436 0
15 ACO 545 ClG 05 32 24.4152 -11 32 35.080           ~ 97 0
16 ACO 3378 ClG 06 05 53.7 -35 18 06           ~ 81 1
17 MARD J061735.4-474656 ClG 06 16 51.4 -47 47 41           ~ 34 0
18 ACO S 592 ClG 06 38 49.40 -53 58 40.8           ~ 61 0
19 ACO 3404 ClG 06 45 29.50 -54 13 37.0           ~ 96 0
20 ClG 0657-56 ClG 06 58 29.6 -55 56 39           ~ 963 1
21 ZwCl 0735+7421 ClG 07 41 40.3 +74 14 58     17.70     ~ 254 0
22 ClG 0745-19 ClG 07 47 31.3 -19 17 40           ~ 372 0
23 2MASX J07473129-1917403 BiC 07 47 31.3247085936 -19 17 40.013334276   19.60       ~ 410 1
24 ACO 665 ClG 08 30 45.2 +65 52 55           ~ 437 0
25 ACO 689 ClG 08 37 29 +14 59.5           ~ 51 0
26 ACO 754 ClG 09 09 08.4 -09 39 58           ~ 667 1
27 ACO 773 ClG 09 17 51.3 +51 43 20           ~ 295 0
28 NAME Hya A LIN 09 18 05.66848602 -12 05 43.8060823   14.38 14.8     ~ 1013 1
29 ACO 781 ClG 09 20 25.4 +30 30 07           ~ 154 0
30 ACO 907 ClG 09 58 21.84 -11 03 47.5           ~ 129 0
31 ACO 963 ClG 10 17 03.4 +39 02 56           ~ 400 0
32 ZwCl 1021+0426 ClG 10 23 39.0 +04 11 14   15.6 17.95     ~ 283 0
33 NAME Hydra I Cluster ClG 10 36 36.0 -27 31 04           ~ 840 1
34 ACO 1068 ClG 10 40 47.1 +39 57 19           ~ 214 0
35 ACO 1084 ClG 10 44 37.1 -07 04 47           ~ 74 0
36 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 320 0
37 ACO 1201 ClG 11 12 54.4 +13 26 08           ~ 115 1
38 ACO 1413 ClG 11 55 12.87 +23 23 46.9           ~ 430 0
39 NAME Virgo Cluster ClG 12 26 32.1 +12 43 24           ~ 6653 0
40 ACO 3526 ClG 12 48 51.8 -41 18 21           ~ 1068 2
41 ACO 1656 ClG 12 59 44.40 +27 54 44.9           ~ 4809 2
42 ACO 1689 ClG 13 11 29.5 -01 20 28           ~ 1125 0
43 BAX 199.3086-25.5133 ClG 13 14 25.4 -25 15 44           ~ 102 0
44 ACO 3558 ClG 13 27 54.8 -31 29 32           ~ 443 2
45 ACO 1758 ClG 13 32 32.1 +50 30 37           ~ 252 2
46 ACO 1763 ClG 13 35 20.1 +41 00 04           ~ 312 0
47 ACO 3571 ClG 13 47 28.9 -32 51 57           ~ 285 2
48 ACO 1835 ClG 14 01 02.07 +02 52 43.2           ~ 689 1
49 ACO 3581 ClG 14 07 29.8 -27 01 04           ~ 184 3
50 ACO 1914 ClG 14 26 03.32 +37 49 58.7           ~ 314 0
51 ClG J1504-0248 ClG 15 04 07.4 -02 48 15           ~ 175 0
52 NAME UMi Galaxy G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1363 0
53 ACO 2034 ClG 15 10 12.96 +33 29 53.2           ~ 215 1
54 ACO 2063 ClG 15 23 01.8 +08 38 22           ~ 398 2
55 ClG J1532+3021 ClG 15 32 53.8 +30 21 00           ~ 113 0
56 ACO 2147 ClG 16 02 11.96 +15 55 11.5           ~ 404 0
57 ACO 2163 ClG 16 15 46.1 -06 08 50           ~ 563 0
58 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3632 1
59 ACO 2204 ClG 16 32 45.7 +05 34 43           ~ 436 0
60 ACO 2218 ClG 16 35 54.0 +66 13 00           ~ 809 1
61 BAX 249.5848-64.5165 ClG 16 38 16.1 -64 20 50           ~ 115 0
62 NAME LHB X 16 42.0 +02 19           ~ 347 0
63 NAME Oph Cluster ClG 17 12 24.7 -23 21 01           ~ 273 0
64 ACO 2254 ClG 17 17 45.90 +19 40 22.8           ~ 69 0
65 ClG J1720+2638 ClG 17 20 09.6 +26 37 35           ~ 255 0
66 ACO 2319 ClG 19 20 45.3 +43 57 43           ~ 461 1
67 NAME Cyg A Sy2 19 59 28.35656837 +40 44 02.0972325   16.22 15.10     ~ 2372 2
68 ACT-CL J2014.8-2430 ClG 20 14 49.7 -24 30 30           ~ 83 0
69 ACO 2345 ClG 21 27 05.391 -12 09 07.41           ~ 131 0
70 NVSS J212709-120958 Rad 21 27 09.5 -12 09 58           ~ 132 1
71 ClG J2129+0005 ClG 21 29 40.5 +00 05 47           ~ 271 0
72 ClG 2137-2353 ClG 21 40 12.8 -23 39 27     18.5     ~ 378 0
73 ACO 2390 ClG 21 53 37.4 +17 41 46           ~ 688 2
74 ACO 3856 ClG 22 18 45.2 -38 53 57           ~ 79 2
75 ClG J2229-2756 ClG 22 29 45.36 -27 55 36.5           ~ 46 0
76 ACO 3888 ClG 22 34 23.0 -37 43 29           ~ 138 1
77 ACO S 1063 ClG 22 48 45.4 -44 31 42           ~ 320 0
78 ACO S 1101 ClG 23 13 58.5 -42 43 39           ~ 258 1
79 ACO 2597 ClG 23 25 19.70 -12 07 27.7           ~ 539 0
80 ACO 4038 ClG 23 47 31.1 -28 12 10           ~ 335 3
81 ACO 2667 ClG 23 51 39.37 -26 05 02.7           ~ 175 0
82 ACO 4059 ClG 23 57 02.2 -34 45 58           ~ 381 1

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