2004ApJ...608..680A
TeV Gamma-Ray Survey of the Northern Hemisphere Sky Using the Milagro Observatory
Atkins, R. ( University of Wisconsin, Madison, WI 53706; University of Utah, Salt Lake City, UT 84112. ); Benbow, W. ( University of California, Santa Cruz, CA 95064; Max-Planck-Institute, Heidelberg, Germany ); Berley, D. ( University of Maryland, College Park, MD 20742. ); Blaufuss, E. ( University of Maryland, College Park, MD 20742. ); Bussons, J. ( University of Maryland, College Park, MD 20742; Université de Montpellier II, Montpellier, France ); Coyne, D. G. ( University of California, Santa Cruz, CA 95064. ); De Young, T. ( University of California, Santa Cruz, CA 95064; University of Maryland, College Park, MD 20742. ); Dingus, B. L. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Dorfan, D. E. ( University of California, Santa Cruz, CA 95064. ); Ellsworth, R. W. ( George Mason University, Fairfax, VA 22030. ); Fleysher, L. ( New York University, New York, NY 10003. ); Fleysher, R. ( New York University, New York, NY 10003. ); Gisler, G. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Gonzalez, M. M. ( University of Wisconsin, Madison, WI 53706. ); Goodman, J. A. ( University of Maryland, College Park, MD 20742. ); Haines, T. J. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Hays, E. ( University of Maryland, College Park, MD 20742. ); Hoffman, C. M. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Kelley, L. A. ( University of California, Santa Cruz, CA 95064. ); Lansdell, C. P. ( University of Maryland, College Park, MD 20742. ); Linnemann, J. T. ( Michigan State University, East Lansing, MI 48824. ); McEnery, J. E. ( University of Wisconsin, Madison, WI 53706; NASA Goddard Space Flight Center, Greenbelt, MD 20771. ); Miller, R. S. ( University of New Hampshire, Durham, NH 03824; University of Alabama in Hunstville, Huntsville, AL 35899. ); Mincer, A. I. ( New York University, New York, NY 10003. ); Morales, M. F. ( University of California, Santa Cruz, CA 95064; Massachusetts Institute of Technology, Cambridge, MA 02139. ); Nemethy, P. ( New York University, New York, NY 10003. ); Noyes, D. ( University of Maryland, College Park, MD 20742. ); Ryan, J. M. ( University of New Hampshire, Durham, NH 03824. ); Samuelson, F. W. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Shoup, A. ( University of California, Irvine, CA 92717. ); Sinnis, G. ( Los Alamos National Laboratory, Los Alamos, NM 87545; Los Alamos National Laboratory, MS H803, Los Alamos, NM 87545 ); Smith, A. J. ( University of Maryland, College Park, MD 20742. ); Sullivan, G. W. ( University of Maryland, College Park, MD 20742. ); Williams, D. A. ( University of California, Santa Cruz, CA 95064. ); Westerhoff, S. ( University of California, Santa Cruz, CA 95064; Columbia University, New York, NY 10027. ); Wilson, M. E. ( University of Wisconsin, Madison, WI 53706. ); Xu, X. W. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Yodh, G. B. ( University of California, Irvine, CA 92717. ) and 28 coauthors show affiliations
The Astrophysical Journal, Volume 608, Issue 2, pp. 680-685.
Published in Jun 2004
Milagro is a water Cerenkov extensive air shower array that continuously monitors the entire overhead sky in the TeV energy band. The results from an analysis of ~3 yr of data (2000 December-2003 November) are presented. The data have been searched for steady point sources of TeV gamma rays between declinations of 1.1d and 80°. Two sources are detected, the Crab Nebula and the active galaxy Mrk 421. For the remainder of the northern hemisphere, we set 95% confidence level (CL) upper limits between 275 and 600 mcrab (4.8×10-12 to 10.5×10-12 cm-2 s-1) above 1 TeV for source declinations between 5° and 70°. Since the sensitivity of Milagro depends on the spectrum of the source at the top of the atmosphere, the dependence of the limits on the spectrum of a candidate source is presented. Because high-energy gamma rays from extragalactic sources are absorbed by interactions with the extragalactic background light, the dependence of the flux limits on the redshift of a candidate source are given. The upper limits presented here are over an order of magnitude more stringent than previously published limits from TeV gamma-ray all-sky surveys.
Keywords:
Free Keywords: Galaxies: Active; Gamma Rays: Observations; Surveys
Astronomy: Galaxies: Active; Gamma Rays: Observations; Surveys
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