2011A&A...531A..56D


Query : 2011A&A...531A..56D

2011A&A...531A..56D - Astronomy and Astrophysics, volume 531A, 56-56 (2011/7-1)

Searching for the 511 keV annihilation line from galactic compact objects with the IBIS gamma ray telescope.

DE CESARE G.

Abstract (from CDS):

The first detection of a gamma ray line with an energy of about 500keV from the center of our Galaxy dates back to the early seventies. Thanks to the astrophysical application of high spectral resolution detectors, it was soon clear that this radiation was due to the 511keV photons generated by electron-positron annihilation. Even though the physical process are known, the astrophysical origin of this radiation is still a mystery. The spectrometer SPI aboard the INTEGRAL gamma-ray satellite has been used to produce the first all-sky map in light of the 511keV annihilation, but no direct evidence of any 511keV galactic compact objects has been found. Owing to its moderate angular resolution, these SPI data are still compatible with a distribution of point sources clustered in the bulge of our Galaxy. Thanks to the fine angular resolution and the large field of view, the IBIS imager on the INTEGRAL satellite gives us the unique opportunity to search for a possible 511keV line from point sources associated to known objects, such as X-ray binaries, or supernovae, or even new ones. We present the first deep IBIS 511keV all-sky map, obtained by applying standard analysis to about 5 years of data. Possible 511keV signals are also searched over hour-day-month timescales. The IBIS sensitivity at 511keV depends on the detector quantum efficiency at this energy and on the background. Both these quantities were estimated in this work. We find no evidence of Galactic 511keV point sources. With an exposure of 10Ms, in the center of the Galaxy, we estimate a 1.6x10–4ph/cm2/s flux 2 sigma upper limit. A similar limit is given in a wide area in the Galactic center region with similar exposures. The IBIS 511keV flux upper limits for microquasars and supernova remnants detected in the hard X domain (E>20keV) are also reported. Our results are consistent with a diffuse e+e annihilation scenario. If positrons are generated in compact objects, we expect that a significant fraction of them propagate in the interstellar medium before they are annihilated away from their birth places.

Abstract Copyright:

Journal keyword(s): methods: data analysis - Galaxy: bulge - gamma rays: diffuse background - X-rays: binaries

Simbad objects: 24

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Number of rows : 24
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 SN 1572A SN* 00 25 21.5 +64 08 27           B8 1189 1
2 M 1 SNR 05 34 30.9 +22 00 53           ~ 6202 1
3 V* CM Tau Psr 05 34 31.9474694616 +22 00 52.153698024           ~ 5268 0
4 V* V1055 Ori LXB 06 17 07.3565603963 +09 08 13.515857360   18.80 18.5     ~ 560 1
5 V* V381 Nor HXB 15 50 58.6637920704 -56 28 35.258385000   17.95 16.6     K3III 1175 0
6 V* V818 Sco LXB 16 19 55.0692669024 -15 38 25.017666540 11.60 12.40 11.1     Oev 1644 0
7 V* V1033 Sco HXB 16 54 00.137 -39 50 44.90   15.20 14.2 16.14   F5IV 1888 1
8 V* V821 Ara HXB 17 02 49.3876391280 -48 47 23.087954544 16.20 16.30 15.5     ~ 2089 0
9 NAME Great Annihilator LXB 17 43 54.83 -29 44 42.6           ~ 674 1
10 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14463 0
11 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4400 3
12 2XMM J180112.4-254436 LXB 18 01 12.40 -25 44 36.1           ~ 392 1
13 PSR J1811-1926 Psr 18 11 29.15 -19 25 25.4           ~ 127 1
14 NAME AGPS 273.4-17.8 SNR 18 13 35.05 -17 49 58.1           ~ 126 2
15 SNR G021.5-00.9 SNR 18 33 33.612 -10 34 07.69           ~ 461 1
16 AX J1838.0-0655 BL? 18 38 03.13 -06 55 33.4           ~ 78 2
17 4C -04.71 Rad 18 41 19.8 -04 56 06           ~ 327 3
18 AX J1846.4-0258 Psr 18 46 24.5 -02 58 28           ~ 26 0
19 SS 433 HXB 19 11 49.5647697480 +04 58 57.827127648   16.854 14.643     A3/7I 2125 4
20 Granat 1915+105 HXB 19 15 11.55576 +10 56 44.9052           ~ 2633 0
21 HD 226868 HXB 19 58 21.6757355952 +35 12 05.784512688 9.38 9.72 8.91 8.42   O9.7Iabpvar 4349 0
22 V* V1521 Cyg HXB 20 32 25.78 +40 57 27.9           WN4/5-6/7 1942 2
23 3C 461 BL? 23 23 24.000 +58 48 54.00     14.30     ~ 2797 1
24 NAME Galactic Bulge reg ~ ~           ~ 4309 0

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