2005ApJ...634L..21B

Query : 2005ApJ...634L..21B

2005ApJ...634L..21B - Astrophys. J., 634, L21-L24 (2005/November-3)

Is the INTEGRAL IBIS source IGR J17204-3554 a gamma-ray-emitting galaxy hidden behind the molecular cloud NGC 6334?

BASSANI L., DE ROSA A., BAZZANO A., BIRD A.J., DEAN A.J., GEHRELS N., KENNEA J.A., MALIZIA A., MOLINA M., STEPHEN J.B., UBERTINI P. and WALTER R.

Abstract (from CDS):

We report on the identification of a soft gamma-ray source, IGR J17204-3554, detected with IBIS, the Imager on Board the INTEGRAL Satellite. The source has a 20-100 keV flux of ∼3x10–11 ergs/cm2/s and is spatially coincident with NGC 6334, a molecular cloud located in the Sagittarius arm of the Milky Way. Diffuse X-ray emission has been reported from this region by ASCA and interpreted as coming from five far-infrared cores located in the cloud. However, the combined ASCA spectrum with a 9 keV temperature was difficult to explain in terms of emission from young pre-main-sequence stars known to be embedded in the star-forming regions. Detection of gamma rays makes this interpretation even more unrealistic and suggests the presence of a high-energy source in or behind the cloud. Follow-up observations with Swift and archival Chandra data allow us to disentangle the NGC 6334 enigma by locating an extragalactic object with the proper spectral characteristics to explain the gamma-ray emission. The combined Chandra-IBIS spectrum is well fitted by an absorbed power law with Γ=1.2±0.1, NH=(1.4±0.1)x1023/cm2, and an unabsorbed 2-10 keV flux of 0.5x10–11 ergs/cm2/s. This column density is in excess of the Galactic value, implying that we are detecting a background galaxy concealed by the molecular cloud and further hidden by material located either in the galaxy itself or between IGR J17204-3554 and the cloud.

Abstract Copyright: ∼

Journal keyword(s): Galaxies: Active - Gamma Rays: Observations - ISM: Clouds - X-Rays: General

CDS comments: Parag. 3.2 : Source 1 = 2E 1717.1-3548, Source 2 = CD -35 11482, Source 3 = NGC 6334B

Simbad objects: 21

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Number of rows : 21
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 NAME NGC 6334 FIR V Cl* 17 19 57 -35 57.5           ~ 99 0
2 NAME NGC 6334-VI Cl* 17 19 59 -36 09.7           ~ 6 0
3 NAME NGC 6334-IV Cl* 17 20 17 -35 54.9           ~ 48 1
4 NGC 6334A HII 17 20 19.3 -35 54 55           ~ 123 0
5 NGC 6334B rG 17 20 21.810 -35 52 48.25           ~ 113 0
6 CD-35 11482 Be* 17 20 26.4739189080 -35 44 06.898072524 11.08 10.99 10.12 10.19   B0.5:Ve 30 1
7 GAL 351.31+00.6 HII 17 20 31 -35 51.6           ~ 46 0
8 2MASS J17203178-3551111 Y*O 17 20 31.7720826600 -35 51 11.312867016           O7 10 0
9 NAME NGC 6334-III Cl* 17 20 32 -35 51.5           ~ 25 1
10 NGC 6334D HII 17 20 44.2 -35 49 18           ~ 38 0
11 NAME NGC 6334-II Cl* 17 20 45 -35 49.4           ~ 31 1
12 NGC 6334E HII 17 20 50.9 -35 46 06           ~ 52 0
13 NGC 6334 HII 17 20 53 -36 07.9           ~ 740 0
14 NAME NGC 6334-I Cl* 17 20 53.35 -35 47 01.5           ~ 373 0
15 NAME NGC 6334F (C) HII 17 20 53.45 -35 47 02.6           ~ 244 1
16 2MASS J17251139-3616575 HXB 17 25 11.392 -36 16 57.53     14.30     B0-1Ia 140 2
17 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
18 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4970 3
19 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2443 1
20 CXOGCS J174742.4-282228 MoC 17 47 42.41 -28 22 28.1           ~ 49 1
21 NAME Sgr Arm PoG 19 00 -30.0           ~ 710 1

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