FERMI OBSERVATIONS OF CASSIOPEIA AND CEPHEUS: DIFFUSE GAMMA-RAY EMISSION IN THE OUTER GALAXY

被引：169

作者：

Abdo, A. A. ^{[1
,2
]}

Ackermann, M. ^{[3
,4
]}

Ajello, M. ^{[3
,4
]}

Baldini, L. ^{[5
]}

Ballet, J. ^{[6
]}

Barbiellini, G. ^{[7
,8
]}

Bastieri, D. ^{[9
,10
]}

Baughman, B. M. ^{[11
]}

Bechtol, K. ^{[3
,4
]}

Bellazzini, R. ^{[5
]}

Berenji, B. ^{[3
,4
]}

Bloom, E. D. ^{[3
,4
]}

Bonamente, E. ^{[12
,13
]}

Borgland, A. W. ^{[3
,4
]}

Bregeon, J. ^{[5
]}

Brez, A. ^{[5
]}

Brigida, M. ^{[14
,15
]}

Bruel, P. ^{[16
]}

Burnett, T. H. ^{[17
]}

Buson, S. ^{[10
]}

Caliandro, G. A. ^{[18
]}

Cameron, R. A. ^{[3
,4
]}

Caraveo, P. A. ^{[19
]}

Casandjian, J. M. ^{[6
]}

Cecchi, C. ^{[12
,13
]}

Celik, Oe. ^{[20
,21
,22
,23
]}

Chekhtman, A. ^{[1
,24
]}

Cheung, C. C. ^{[1
,2
]}

Chiang, J. ^{[3
,4
]}

Ciprini, S. ^{[13
]}

Claus, R. ^{[3
,4
]}

Cohen-Tanugi, J. ^{[25
]}

Cominsky, L. R. ^{[26
]}

Conrad, J. ^{[27
,28
]}

Dermer, C. D. ^{[1
]}

de Palma, F. ^{[14
,15
]}

Digel, S. W. ^{[3
,4
]}

do Couto e Silva, E. ^{[3
,4
]}

Drell, P. S. ^{[3
,4
]}

Dubois, R. ^{[3
,4
]}

Dumora, D. ^{[29
,30
]}

Farnier, C. ^{[25
]}

Favuzzi, C. ^{[14
,15
]}

Fegan, S. J. ^{[16
]}

Focke, W. B. ^{[3
,4
]}

Fortin, P. ^{[16
]}

Frailis, M. ^{[31
,32
]}

Fukazawa, Y. ^{[33
]}

Funk, S. ^{[3
,4
]}

Fusco, P. ^{[14
,15
]}

机构：

[1] USN, Res Lab, Div Space Sci, Washington, DC 20375 USA

[2] Natl Acad Sci, Natl Res Council Res Associate, Washington, DC 20001 USA

[3] Stanford Univ, WW Hansen Expt Phys Lab, Kavli Inst Particle Astrophys & Cosmol, Dept Phys, Stanford, CA 94305 USA

[4] Stanford Univ, SLAC Natl Accelerator Lab, Stanford, CA 94305 USA

[5] Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy

[6] Univ Paris Diderot, CNRS, CEA Saclay, Lab AIM,CEA,IRFU,Serv Astrophys, F-91191 Gif Sur Yvette, France

[7] Ist Nazl Fis Nucl, Sez Trieste, I-34127 Trieste, Italy

[8] Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy

[9] Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy

[10] Univ Padua, Dipartimento Fis G Galilei, I-35131 Padua, Italy

[11] Ohio State Univ, Dept Phys, Ctr Cosmol & Astroparticle Phys, Columbus, OH 43210 USA

[12] Ist Nazl Fis Nucl, Sez Perugia, I-06123 Perugia, Italy

[13] Univ Perugia, Dipartimento Fis, I-06123 Perugia, Italy

[14] Univ & Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy

[15] Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy

[16] Ecole Polytech, CNRS, IN2P3, Lab Leprince Ringuet, F-91128 Palaiseau, France

[17] Univ Washington, Dept Phys, Seattle, WA 98195 USA

[18] CSIC, IEEC, Inst Ciencies Espai, Barcelona 08193, Spain

[19] Ist Astrofis Spaziale & Fis Cosm, INAF, I-20133 Milan, Italy

[20] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA

[21] CRESST, Greenbelt, MD 20771 USA

[22] Univ Maryland Baltimore Cty, Dept Phys, Baltimore, MD 21250 USA

[23] Univ Maryland Baltimore Cty, Ctr Space Sci & Technol, Baltimore, MD 21250 USA

[24] George Mason Univ, Fairfax, VA 22030 USA

[25] Univ Montpellier 2, CNRS, IN2P3, Lab Phys Theor & Astroparticules, Montpellier, France

[26] Sonoma State Univ, Dept Phys & Astron, Rohnert Pk, CA 94928 USA

[27] Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden

[28] Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden

[29] CEN Bordeaux Gradignan, CNRS, IN2P3, UMR 5797, F-33175 Gradignan, France

[30] Univ Bordeaux, CEN Bordeaux Gradignan, UMR 5797, F-33175 Gradignan, France

[31] Univ Udine, Dipartimento Fis, I-33100 Udine, Italy

[32] Ist Nazl Fis Nucl, Sez Trieste, Grp Coll Udine, I-33100 Udine, Italy

[33] Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan

[34] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA

[35] Univ Maryland, Dept Phys, College Pk, MD 20742 USA

[36] Univ Maryland, Dept Astron, College Pk, MD 20742 USA

[37] Univ Alabama, CSPAR, Huntsville, AL 35899 USA

[38] Max Planck Inst Radioastron, D-53121 Bonn, Germany

[39] Royal Inst Technol KTH, Dept Phys, SE-10691 Stockholm, Sweden

[40] Waseda Univ, Shinjuku Ku, Tokyo 1698050, Japan

[41] Tokyo Inst Technol, Dept Phys, Meguro, Tokyo 1528551, Japan

[42] RIKEN, Inst Phys & Chem Res, Cosm Radiat Lab, Wako, Saitama 3510198, Japan

[43] UPS, CNRS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse 4, France

[44] Ist Nazl Fis Nucl, Sez Roma Tor Vergata, I-00133 Rome, Italy

[45] Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA

[46] Univ Tokyo, Grad Sch Sci, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan

[47] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany

[48] Univ Calif Santa Cruz, Dept Phys, Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA

[49] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA

[50] Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria

来源：

ASTROPHYSICAL JOURNAL | 2010年 / 710卷 / 01期

基金：

瑞典研究理事会; 美国国家航空航天局;

关键词：

cosmic rays; gamma rays: diffuse background; ISM: clouds; GIANT MOLECULAR CLOUDS; MILKY-WAY; INFRARED-EMISSION; AREA TELESCOPE; HELIUM SPECTRA; IC; 443; GAS; CO; DISCOVERY; RADIATION;

D O I：

10.1088/0004-637X/710/1/133

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the analysis of the interstellar gamma-ray emission measured by the Fermi Large Area Telescope toward a region in the second Galactic quadrant at 100 degrees <= l <= 145 degrees and -15 degrees <= b <= +30 degrees. This region encompasses the prominent Gould Belt clouds of Cassiopeia, Cepheus, and the Polaris flare, as well as atomic and molecular complexes at larger distances, like that associated with NGC 7538 in the Perseus arm. The good kinematic separation in velocity between the local, Perseus, and outer arms, and the presence of massive complexes in each of them, make this region well suited to probe cosmic rays (CRs) and the interstellar medium beyond the solar circle. The gamma-ray emissivity spectrum of the gas in the Gould Belt is consistent with expectations based on the locally measured CR spectra. The gamma-ray emissivity decreases from the Gould Belt to the Perseus arm, but the measured gradient is flatter than expectations for CR sources peaking in the inner Galaxy as suggested by pulsars. The X-CO = N(H-2)/W-CO conversion factor is found to increase from (0.87 +/- 0.05) x 10(20) cm(-2) (K km s(-1))(-1) in the Gould Belt to (1.9 +/- 0.2) x 10(20) cm(-2) (K km s(-1))(-1) in the Perseus arm. We derive masses for the molecular clouds under study. Dark gas, not properly traced by radio and microwave surveys, is detected in the Gould Belt through a correlated excess of dust and gamma-ray emission: its mass amounts to similar to 50% of the CO-traced mass.

引用

页码：133 / 149

页数：17

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