FERMI LARGE AREA TELESCOPE STUDY OF COSMIC RAYS AND THE INTERSTELLAR MEDIUM IN NEARBY MOLECULAR CLOUDS

Ackermann M, Ajello M, Allafort A, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Berenji B, Blandford RD, Bloom ED, Bonamente E, Borgland AW, Bottacini E, Brandt TJ, Bregeon J, Brigida M, Bruel P, Buehler R, Busetto G, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Casandjian JM, Cecchi C, Charles E, Chekhtman A, Chiang J, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, D'Ammando F, De Angelis A, De Palma F, Dermer CD, Digel SW, Do Couto E Silva E, Drell PS, Drlica-Wagner A, Falletti L, Favuzzi C, Fegan SJ, Ferrara EC, Focke WB, Fukazawa Y, Fukui Y, Funk S, Fusco P, Gargano F, Gasparrini D, Germani S, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grondin MH, Grove JE, Guiriec S, Hadasch D, Hanabata Y, Harding AK, Hayashi K, Horan D, Hou X, Hughes RE, Itoh R, Jackson MS, Johannesson G, Johnson AS, Kamae T, Katagiri H, Kataoka J, Knoedlseder J, Kuss MW, Lande J, Larsson S, Lee SH, Lemoine-Goumard M, Longo F, Loparco F, Lovellette MN, Lubrano P, Martin P, Mazziotta MN, Mcenery JE, Mehault J, Michelson PF, Mitthumsiri W, Mizuno T, Moiseev AA, Monte C, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Naumann-Godo M, Nemmen R, Nishino S, Norris JP, Nuss E, Ohno M, Ohsugi T, Okumura A, Omodei N, Orlando E, Ormes JF, Ozaki M, Paneque D, Panetta JH, Parent D, Pesce-Rollins M, Pierbattista M, Piron F, Pivato G, Porter TA, Raino S, Rando R, Razzano M, Reimer A, Reimer O, Romoli C, Roth M, Sada T, Sadrozinski HFW, Sanchez DA, Sbarra C, Sgro C, Siskind EJ, Spandre G, Spinelli P, Strong AW, Suson DJ, Takahashi HH, Takahashi T, Tanaka T, Thayer JG, Thayer JB, Thompson DJ, Tibaldo L, Tibolla O, Tinivella M, Torres DF, Tosti G, Tramacere A, Troja E, Uchiyama Y, Uehara T, Usher TL, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, Waite AP, Wang P, Winer BL, Wood KS, Yamamoto H, Yang Z, Zimmer S (2012)

Publication Type: Journal article

Publication year: 2012

Journal

Book Volume: 755

Journal Issue: 1

DOI: 10.1088/0004-637X/755/1/22

Abstract

We report an analysis of the interstellar gamma-ray emission from the Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions with the Fermi Large Area Telescope. They are among the nearest molecular cloud complexes, within similar to 300 pc from the solar system. The gamma-ray emission produced by interactions of cosmic rays (CRs) and interstellar gas in those molecular clouds is useful to study the CR densities and distributions of molecular gas close to the solar system. The obtained gamma-ray emissivities above 250 MeV are (5.9 +/- 0.1(stat-1.0sys)(+0.9)) x 10(-27) photons s(-1) sr(-1) H-atom(-1), (10.2 +/- 0.4(stat-1.7sys)(+1.2)) x 10(-27) photons s(-1) sr(-1) H-atom(-1), and (9.1 +/- 0.3(stat-0.6sys)(+1.5)) x 10(-27) photons s(-1) sr(-1) H-atom(-1) for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively. Whereas the energy dependences of the emissivities agree well with that predicted from direct CR observations at the Earth, the measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR density by similar to 20% in the neighborhood of the solar system, even if we consider systematic uncertainties. The molecular mass calibrating ratio, X-CO = N(H-2)/W-CO, is found to be (0.96 +/- 0.06(stat-0.12sys)(+0.15)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1), (0.99 +/- 0.08(stat-0.10sys)(+0.18)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1), and (0.63 +/- 0.02(stat-0.07sys)(+0.09)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1) for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively, suggesting a variation of X-CO in the vicinity of the solar system. From the obtained values of X-CO, the masses of molecular gas traced by W-CO in the Chamaeleon, R CrA, and Cepheus and Polaris flare regions are estimated to be similar to 5 x 10(3)M(circle dot), similar to 10(3)M(circle dot), and similar to 3.3 x 10(4)M(circle dot), respectively. A comparable amount of gas not traced well by standard Hi and CO surveys is found in the regions investigated.

Authors with CRIS profile

Involved external institutions

Deutsches Elektronen-Synchrotron DESY Germany (DE) 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) National Center for Scientific Research / Centre national de la recherche scientifique (CNRS) France (FR) University of Udine / Università degli Studi di Udine Italy (IT) Politecnico di Bari Italy (IT) École Polytechnique - Université Paris-Saclay France (FR) University of Iceland (UI) / Háskóli Íslands Iceland (IS) Ibaraki University / 茨城大学 Japan (JP) Institut de Ciències de l'Espai (ICE) Spain (ES) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) Università degli Studi di Perugia Italy (IT) University of Montpellier / Université Montpellier France (FR) Stockholm University / Stockholms universitet Sweden (SE) U.S. Naval Research Laboratory United States (USA) (US) National Aeronautics and Space Administration (NASA) United States (USA) (US) Hiroshima University Japan (JP) Nagoya University / 名古屋大学 Japan (JP) Italian Space Agency / Agenzia Spaziale Italiana (ASI) Italy (IT) Max-Planck-Institut für Kernphysik (MPIK) / Max Planck Institute for Nuclear Physics Germany (DE) University of Alabama in Huntsville (UAH) United States (USA) (US) Université Bordeaux 1, Sciences et Technologies France (FR) Ohio State University United States (USA) (US) Waseda University / 早稲田大学 Japan (JP) Kyoto University / 京都大学 Kyōto daigaku Japan (JP) University of Padua / Universita degli Studi di Padova Italy (IT) University of Washington United States (USA) (US) University of California Santa Cruz United States (USA) (US) NYCB Real-Time Computing, Inc. United States (USA) (US) Max-Planck-Institut für extraterrestrische Physik (MPE) / Max Planck Institute for Extraterrestrial Physics Germany (DE) University of Maryland United States (USA) (US) Boise State University United States (USA) (US) Japan Aerospace eXploration Agency (JAXA) Japan (JP) University of Denver United States (USA) (US) George Mason University United States (USA) (US) Purdue University Northwest / Purdue University Calumet United States (USA) (US) Julius-Maximilians-Universität Würzburg Germany (DE)

How to cite

APA:

Ackermann, M., Ajello, M., Allafort, A., Baldini, L., Ballet, J., Barbiellini, G.,... Zimmer, S. (2012). FERMI LARGE AREA TELESCOPE STUDY OF COSMIC RAYS AND THE INTERSTELLAR MEDIUM IN NEARBY MOLECULAR CLOUDS. Astrophysical Journal, 755(1). https://doi.org/10.1088/0004-637X/755/1/22

MLA:

Ackermann, Markus, et al. "FERMI LARGE AREA TELESCOPE STUDY OF COSMIC RAYS AND THE INTERSTELLAR MEDIUM IN NEARBY MOLECULAR CLOUDS." Astrophysical Journal 755.1 (2012).

BibTeX: Download