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

Abdo AA, Ackermann M, Ajello M, Baldini L, Ballet J, Barbiellini G, Bastieri D, Baughman BM, Bechtol K, Bellazzini R, Berenji B, Bloom ED, Bonamente E, Borgland AW, Bregeon J, Brez A, Brigida M, Bruel P, Burnett TH, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Celik O, Chekhtman A, Cheung CC, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Cominsky LR, Conrad J, Dermer CD, De Palma F, Digel SW, Do Couto E Silva E, Drell PS, Dubois R, Dumora D, Farnier C, Favuzzi C, Fegan SJ, Focke WB, Fortin P, Frailis M, Fukazawa Y, Funk S, Fusco P, Gargano F, Gehrels N, Germani S, Giavitto G, Giebels B, Giglietto N, Giordano F, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guillemot L, Guiriec S, Harding AK, Hayashida M, Horan D, Hughes RE, Jackson MS, Johannesson G, Johnson AS, Johnson WN, Kamae T, Katagiri H, Kataoka J, Kawai N, Kerr M, Knoedlseder J, Kuss MW, Lande J, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Makeev A, Mazziotta MN, Mcenery JE, Meurer C, Michelson PF, Mitthumsiri W, Mizuno T, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nolan PL, Norris JP, Nuss E, Ohsugi T, Okumura A, Omodei N, Orlando E, Ormes JF, Paneque D, Pelassa V, Pepe M, Pesce-Rollins M, Piron F, Porter TA, Raino S, Rando R, Razzano M, Reimer A, Reimer O, Reposeur T, Rodriguez AY, Ryde F, Sadrozinski HFW, Sanchez D, Sander A, Parkinson PMS, Sgro C, Siskind EJ, Smith PD, Spandre G, Spinelli P, Starck JL, Strickman MS, Strong AW, Suson DJ, Takahashi HH, Tanaka T, Thayer JB, Thayer JG, Thompson DJ, Tibaldo L, Torres DF, Tosti G, Tramacere A, Uchiyama Y, Usher TL, Vasileiou V, Vilchez N, Vitale V, Waite AP, Wang P, Winer BL, Wood KS, Ylinen T, Ziegler M (2010)

Publication Type: Journal article

Publication year: 2010

Journal

Book Volume: 710

Pages Range: 133-149

Journal Issue: 1

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

Abstract

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.

Authors with CRIS profile

Involved external institutions

U.S. Naval Research Laboratory United States (USA) (US) Stanford University United States (USA) (US) National Institute for Nuclear Physics / Istituto Nazionale di Fisica Nucleare (INFN) Italy (IT) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR) Ohio State University United States (USA) (US) University of Bari Aldo Moro / Università degli Studi di Bari Aldo Moro Italy (IT) École Polytechnique - Université Paris-Saclay France (FR) University of Washington United States (USA) (US) University of Padua / Universita degli Studi di Padova Italy (IT) Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC) Spain (ES) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) National Aeronautics and Space Administration (NASA) United States (USA) (US) Università degli Studi di Perugia Italy (IT) University of Montpellier / Université Montpellier France (FR) Sonoma State University United States (USA) (US) Stockholm University / Stockholms universitet Sweden (SE) Université Bordeaux 1, Sciences et Technologies France (FR) University of Udine / Università degli Studi di Udine Italy (IT) Waseda University / 早稲田大学 Japan (JP) Tokyo Institute of Technology Japan (JP) Max-Planck-Institut für extraterrestrische Physik (MPE) / Max Planck Institute for Extraterrestrial Physics Germany (DE) University of California Santa Cruz United States (USA) (US) AlbaNova University Centre / Kungliga Tekniska Högskolan AlbaNova Universitetscentrum Sweden (SE) NYCB Real-Time Computing, Inc. United States (USA) (US) Hiroshima University / 広島大学 Japan (JP) Université Toulouse III - Paul Sabatier France (FR) University of Denver United States (USA) (US) University of Tokyo Japan (JP) Purdue University Northwest / Purdue University Calumet United States (USA) (US) University of Alabama in Huntsville (UAH) United States (USA) (US)

How to cite

APA:

Abdo, A.A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G.,... Ziegler, M. (2010). FERMI OBSERVATIONS OF CASSIOPEIA AND CEPHEUS: DIFFUSE GAMMA-RAY EMISSION IN THE OUTER GALAXY. Astrophysical Journal, 710(1), 133-149. https://doi.org/10.1088/0004-637X/710/1/133

MLA:

Abdo, A. A., et al. "FERMI OBSERVATIONS OF CASSIOPEIA AND CEPHEUS: DIFFUSE GAMMA-RAY EMISSION IN THE OUTER GALAXY." Astrophysical Journal 710.1 (2010): 133-149.

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