Evidence of TeV gamma-ray emission from the nearby 
starburst galaxy NGC 253

Itoh, C.; Enomoto, R.; Yanagita, S.; Yoshida, Tatsuo; Tanimori, T.; Okumura, Ko; Asahara, A.; Bicknell, G. V.; Clay, R. W.; Edwards, Philip; Gunji, Shuichi; Hara, Shinji; Hara, T.; Hattori, Takahiro; Hayashi, S.; Kabuki, S.; Kajino, F.; Kawachi, A.; Kifune, T.; Kubo, H.; Kushida, J.; Matsubara, Y.; Mizumoto, Y.; Mori, M.; Moro, H.; Muraishi, H.; Muraki, Y.; Naito, T.; Nakase, T.; Nishida, D.; Nishijima, K.; Ohishi, M.; Patterson, Joseph; Protheroe, R. J.; Sakurazawa, K.; Swaby, D. L.; Tokanai, Fuyuki; Tsuchiya, K.; Tsunoo, Hajime; Uchida, Tomohisa; Watanabe, Akira; Watanabe, S.; Yoshikoshi, T.

doi:10.1051/0004-6361:20030247

Cited by 23 publications

(29 citation statements)

References 30 publications

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“…Our angular resolution was estimated to be 0Њ .32, slightly larger than the radius of the 65% contour, consistent with the point-source assumption. The acceptance of the CANGA-ROO-II telescope is a smoothly decreasing function with an offset from the tracking center, falling to 50% at a 0Њ .9 offset (see Itoh et al 2003 …”

Section: Resultsmentioning

confidence: 99%

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

Tsuchiya

Enomoto

Ksenofontov

et al. 2004

ApJ

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165

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We have detected sub-TeV gamma-ray emission from the direction of the Galactic center (GC) using the CANGAROO-II Imaging Atmospheric Cerenkov Telescope. We detected a statistically significant excess at energies greater than 250 GeV. The flux was 1 order of magnitude lower than that of the Crab Nebula at 1 TeV with a soft spectrum proportional to . The signal centroid is consistent with the GC direction, and the Ϫ4.6‫5.0ע‬E observed profile is consistent with a pointlike source. Our data suggest that the GeV source 3EG J1746Ϫ2851 is identical to this TeV source, and we study the combined spectra to determine the possible origin of the gammaray emission. We also obtain an upper limit on the cold dark matter density in the Galactic halo.

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Section: Resultsmentioning

confidence: 99%

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

Tsuchiya

Enomoto

Ksenofontov

et al. 2004

ApJ

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165

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“…2a and 2b are 50 and 38 events, respectively. The blue is an expected yield under the assumption of the CANGAROO-II flux (Itoh et al 2003b) for point source assumption. Our upper limit is inconsistent with the CANGAROO-II detection under the assumption of the pointsource and is marginal under that of 0.5-degree diffuse emission.…”

Section: Resultsmentioning

confidence: 99%

“…The blue is that for 0.5-degree diffuse case. The CANGAROO-II data points were obtained from Table 6 of Itoh et al (2003b). Since they are differential, we multiplied E/(γ − 1) bin by bin bases (the black points with error bars).…”

Section: Resultsmentioning

confidence: 99%

“…The total light collection area is 57.3 m 2 . The first telescope, T1, which was the CANGAROO-II telescope (Itoh et al 2003b), is not presently in use due to its smaller field of view and higher energy threshold. The second, third, and fourth telescopes (T2, T3, and T4) were used for the observations described here.…”

Section: Observationmentioning

confidence: 99%

“…In 2002 CANGAROO-II reported on the detection of a diffuse TeV gamma-rays in the direction of NGC 253 (Itoh et al 2002(Itoh et al , 2003b. The estimated size was 0.3 ∼ 0.6 degrees in radius.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of TeV gamma-ray emission from the nearby starburst galaxy NGC 253

Itoh

Enomoto²,

Yanagita

et al. 2006

A&A

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Aims. The CANGAROO-II telescope observed sub-TeV gamma-ray emission from the nearby starburst galaxy NGC 253. The emission region was extended with a radial size of 0.3-0.6 degree. On the contrary, HESS could not confirm this emission and gave upper limits at the level of the CANGAROO-II flux. In order to resolve this discrepancy, we analyzed new observational results for NGC 253 by CANGAROO-III and also assessed the results by CANGAROO-II. Methods. Observation was made with three telescopes of the CANGAROO-III in October 2004. We analyzed three-fold coincidence data by the robust Fisher Discriminant method to discriminate gamma ray events from hadron events. Results. The result by the CANGAROO-III was negative. The upper limit of gamma ray flux was 5.8% Crab at 0.58 TeV for pointsource assumption. In addition, the significance of the excess flux of gamma-rays by the CANGAROO-II was lowered to less than 4 sigma after assessing treatment of malfunction of photomultiplier tubes.

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Search for TeV Gamma-Rays from 3EG J1234-1318 with the CANGAROO-II Telescope

Hattori

Nishijima

Multiwavelength Approach to Unidentified Gamma-Ray Sources

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Evidence of TeV gamma-ray emission from the nearby starburst galaxy NGC 253

Cited by 23 publications

References 30 publications

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

Evidence of TeV gamma-ray emission from the nearby starburst galaxy NGC 253

Search for TeV Gamma-Rays from 3EG J1234-1318 with the CANGAROO-II Telescope

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