A search for ultra-high energy gamma-rays emitted by the young, nearby supernova remnant that was discovered recently by the COMPTEL and ROSAT satellites was made using the JANZOS database for the period 1987-1993. A 95% confidence upper limit on the flux above 100 TeV of 3x10^(-13)cm^(-2)sec^(-1) was obtained. This is an order of magnitude below the expected flux based on the standard model of cosmic ray acceleration in supernova shocks. An optical survey of the region that has been commenced is also reported. This uses UK and ESO Schmidt plates, and CCD images by a NZ/Japan microlensing group.

The data base for the JANZOS air shower array has been examined for evidence of 100 TeV gamma ray emission by twenty-one southern supernova remnants for the period October 1987 to January 1993. Results are presented below.

Various objects in the Magellanic Clouds were monitored for ultra-high-energy (UHE) gamma-ray emission during 1988 and 1990 using Cerenkov technique at large zenith angles with the JANZOS facility. During 1990 the equipment was modified to allow a sky coverage of 7-degrees x 23-degrees at large zenith angles. This enabled most of the extent of the Large Magellanic Cloud to be surveyed at ultra-high energies. An examination of the data base yielded no clear eivdence for persistent UHE emission from SN 1987A and selected X-ray pulsars in the Magellanic Clouds. Upper limits on the UHE fluxes (in cm-2 s-1) above the given threshold energies were obtained as follows: SMC X-1, 2.6 x 10(-13) (>30 TeV); SN 1987A, 3.8 x 10(-13) (>65 TeV); PSR 0540-693, 3.7 x 10(-13) (>65 TeV); A0538-66, 1.1 X 10(-13) (> 130 Tev); LMC X-4, 3.5 x 10(-13) (>140 TeV). We then examined the data base for pulsed UHE emission from PSR 0540-693 at the well-determined X-ray period (50 ms); and for the X-ray binary systems SMC X-1 and LMC X-4, we carried out pulsar periodicity searches on a night-by-night basis near their respective X-ray periods. No statistically significant evidence for pulsed UHE emission was found for these objects. The data base was further examined for evidence of previously undetected UHE sources in the Magellanic Clouds, and no significant DC excesses were found. Finally, we obtained upper limits on the UHE gamma-ray emission from these galaxies as a whole of 1.9 x 10(-12) cm-2 s-1 msr-1 (>30 TeV) for the SMC and 1.8 x 10(-13) cm-2 s-1 msr-1 (>65 TeV) for the LMC.

We have searched for evidence of ultra-high energy gamma rays from the active galaxy Centaurus A in the data set of the JANZOS experiment during the period 13 October 1987 to 18 January 1992. No significant DC excess was found from this source. Excess events were found, however, in the period 14 April – 3 June 1990. The duration of the excess, 48 days, and equivalent luminosity, ~ 1043 erg s−1, are both similar to those measured previously for X-ray outbursts of Centaurus A. Furthermore, the events appear to exhibit the expected absorption feature at 200 TeV due to interactions with the 2.7 K background radiation, but the chance probability for the excess is at the 2% level. The equivalent time averaged flux during this period was (5.5 ± 1.5) × 10−12 photons cm−2s−1 at energies ≥ 110 TeV, about 20 times as large as the upper lim of steady emission, assuming a differential spectral index of −2.0. Further observations are required to confirm the result

The active galaxy Centaurus A and the X-ray binary systems Vela X-1, Centaurus X-3, and Circinus X-1 were monitored for VHE gamma-ray emission above 1 TeV with the JANZOS Cerenkov facility during 1988 and 1989. No evidence was found for persistent or episodic emission from any of these objects. Subseqeunt upper limits on the integral fluxes of 2.2 x 10(-11), 2.8 x 10(-11), 4.0 x 10(-11), and 4.2 x 10(-11) cm-2 s-1, respectively, were obtained for these objects. These limits are consistent with results of observations made by other groups.

A search for point sources of gamma rays with energies greater than or similar to 100 TeV which has been made by the JANZOS Collaboration using an array of plastic scintillators located at Black Birch mountain in New Zealand is reported. The physical characteristics of the array are described, and also the techniques which have been used to analyze the data. Measurements of the angular resolution of the array using the Moon and/or Sun shadowing technique, and also a comparison test with the JANZOS array of Cerenkov mirrors, are reported. About 80 million events were observed in the period October 1987 to January 1992. Upper limits on the average gamma-ray fluxes at energies greater than or similar 100 TeV from SN 1987A, Vela Pulsar Vela X-1, LMC X-4, Sco X-1, Cen X-3, SMC X-1, Galactic Center, Cen A, 4U1145-619, 2Al822-371, and PSR1706-44 in this period are reported. The limits are compared with previous measurements which were made at various energies by several groups. Monthly measurements for the flux from SN1987A are also reported, and a search of the southern sky for unknown sources of ultrahigh energy gamma rays is described. Some plans for future observations are given.

view Abstract Citations (10) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Upper Limit for Ultra--High-Energy Gamma Rays from SN 1987A Obtained by Cherenkov Technique at Large Zenith Angles Bond, I. A. ; Budding, E. ; Conway, M. J. ; Fenton, K. B. ; Fujii, H. ; Fujii, Z. ; Fujimoto, M. ; Hasegawa, H. ; Hayashida, S. ; Honda, M. ; Hotta, N. ; Humble, J. E. ; Kabe, S. ; Kasahara, K. ; Kifune, T. ; Lythe, G. D. ; Masaike, A. ; Matsubara, Y. ; Mitsui, K. ; Miura, Y. ; Mori, M. ; Murakami, K. ; Muraki, Y. ; Nagano, M. ; Nakamura, K. ; Nakamura, T. ; Norris, P. M. ; Ogio, S. ; Ohashi, Y. ; Okada, A. ; Saito, To. ; Sakata, M. ; Sato, H. ; Shibata, S. ; Shima, M. ; Shimizu, H. M. ; Spencer, M. ; Storey, J. R. ; Tanimori, T. ; Teshima, M. ; Torii, S. ; Uchino, K. ; Watase, Y. ; Woodhams, M. D. ; Yamamoto, Y. ; Yock, P. C. M. ; Yuda, T. ; JANZOS Collaboration Abstract The supernova SN 1987A has been observed with the JANZOS cosmic-ray facility at the Black Birch Range in New Zealand since 1987 October. From 1988 May to July, observations were carried out using the Cerenkov telescope at a zenith angle of 68^deg^. By working at large zenith angles, the effective detection area and energy threshold are both increased. From 39 hr of observation, an upper bound of 5.7 x 10^-14^ cm^-2^ s^-1^ on the flux of gamma rays with energies >= 75 TeV is obtained 95% confidence level. This flux limit corresponds to the gamma ray luminosity of 10^37^ ergs s^-1^. Publication: The Astrophysical Journal Pub Date: September 1989 DOI: 10.1086/185520 Bibcode: 1989ApJ...344L..17B Keywords: Cerenkov Counters; Gamma Ray Astronomy; Supernova 1987a; Angular Distribution; Energy Spectra; Astrophysics; GAMMA RAYS: GENERAL; STARS: SUPERNOVAE full text sources ADS | data products NED (2) SIMBAD (1)