2012ApJ...755...22A

Query : 2012ApJ...755...22A

2012ApJ...755...22A - Astrophys. J., 755, 22 (2012/August-2)

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 R.D., BLOOM E.D., BONAMENTE E., BORGLAND A.W., BOTTACINI E., BRANDT T.J., BREGEON J., BRIGIDA M., BRUEL P., BUEHLER R., BUSETTO G., BUSON S., CALIANDRO G.A., CAMERON R.A., CARAVEO P.A., CASANDJIAN J.M., 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 C.D., DIGEL S.W., DO COUTO E SILVA E., DRELL P.S., DRLICA-WAGNER A., FALLETTI L., FAVUZZI C., FEGAN S.J., FERRARA E.C., FOCKE W.B., 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 I.A., GRONDIN M.-H., GROVE J.E., GUIRIEC S., HADASCH D., HANABATA Y., HARDING A.K., HAYASHI K., HORAN D., HOU X., HUGHES R.E., ITOH R., JACKSON M.S., JOHANNESSON G., JOHNSON A.S., KAMAE T., KATAGIRI H., KATAOKA J., KNODLSEDER J., KUSS M., LANDE J., LARSSON S., LEE S.-H., LEMOINE-GOUMARD M., LONGO F., LOPARCO F., LOVELLETTE M.N., LUBRANO P., MARTIN P., MAZZIOTTA M.N., McENERY J.E., MEHAULT J., MICHELSON P.F., MITTHUMSIRI W., MIZUNO T., MOISEEV A.A., MONTE C., MONZANI M.E., MORSELLI A., MOSKALENKO I.V., MURGIA S., NAUMANN-GODO M., NEMMEN R., NISHINO S., NORRIS J.P., NUSS E., OHNO M., OHSUGI T., OKUMURA A., OMODEI N., ORLANDO E., ORMES J.F., OZAKI M., PANEQUE D., PANETTA J.H., PARENT D., PESCE-ROLLINS M., PIERBATTISTA M., PIRON F., PIVATO G., PORTER T.A., RAINO S., RANDO R., RAZZANO M., REIMER A., REIMER O., ROMOLI C., ROTH M., SADA T., SADROZINSKI H.F.-W., SANCHEZ D.A., SBARRA C., SGRO C., SISKIND E.J., SPANDRE G., SPINELLI P., STRONG A.W., SUSON D.J., TAKAHASHI H., TAKAHASHI T., TANAKA T., THAYER J.G., THAYER J.B., THOMPSON D.J., TIBALDO L., TIBOLLA O., TINIVELLA M., TORRES D.F., TOSTI G., TRAMACERE A., TROJA E., UCHIYAMA Y., UEHARA T., USHER T.L., VANDENBROUCKE J., VASILEIOU V., VIANELLO G., VITALE V., WAITE A.P., WANG P., WINER B.L., WOOD K.S., YAMAMOTO H., YANG Z. and ZIMMER S.

Abstract (from CDS):

We report an analysis of the interstellar γ-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 ∼300 pc from the solar system. The γ-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 γ-ray emissivities above 250 MeV are (5.9±0.1stat+0.9–1.0sys)x10–27 photons/s/sr H-atom–1, (10.2±0.4stat+1.2–1.7sys)x10–27 photons/s/sr H-atom–1, and (9.1±0.3stat+1.5–0.6sys)x10–27 photons/s/sr 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 ∼20% in the neighborhood of the solar system, even if we consider systematic uncertainties. The molecular mass calibrating ratio, XCO= N(H2)/WCO, is found to be (0.96±0.06stat+0.15–0.12sys)x1020 H2-molecule/cm2 (K km/s)–1, (0.99±0.08stat+0.18–0.10sys)x1020 H2-molecule/cm2 (K km/s)–1, and (0.63±0.02stat+0.09–0.07sys)x1020 H2-molecule/cm2 (K km/s)–1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively, suggesting a variation of XCO in the vicinity of the solar system. From the obtained values of XCO, the masses of molecular gas traced by WCO in the Chamaeleon, R CrA, and Cepheus and Polaris flare regions are estimated to be ∼5x103 M☉, ∼103 M☉, and ∼3.3x104 M☉, respectively. A comparable amount of gas not traced well by standard H I and CO surveys is found in the regions investigated.

Abstract Copyright: ∼

Journal keyword(s): cosmic rays - gamma rays: ISM

Errata: erratum vol. 778, art. 82 (2013)

Simbad objects: 18

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Number of rows : 18
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 * alf UMi cC* 02 31 49.09456 +89 15 50.7923 3.00 2.62 2.02 1.53 1.22 F8Ib 716 2
2 NAME Orion Molecular Cloud MoC 05 56 -01.8           ~ 1227 1
3 NAME Polaris Flare MoC 11 00 14.8 +86 10 52           ~ 215 1
4 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 887 0
5 NAME Fermi Bubbles bub 17 45 -29.0           ~ 525 0
6 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
7 PMN J1816-4943 rG 18 16 55.99425 -49 43 44.6729           ~ 43 1
8 QSO B1821-525 QSO 18 25 13.8085148136 -52 30 58.288523544   19.2       ~ 53 1
9 ICRF J183000.8-444111 Bla 18 30 00.8695507752 -44 41 11.680546056           ~ 43 1
10 NAME Corona Australis Cloud MoC 19 01 51 -36 58.9           ~ 554 0
11 V* R CrA Ae* 19 01 53.6764322232 -36 57 08.299341828 12.781 12.651 11.917 11.242 10.412 B5IIIpe 499 2
12 1FGL J1903.8-3718c gam 19 03 52 -37 18.5           ~ 9 0
13 NAME CrA Complex reg 19 15 00.0 -37 30 00           ~ 118 1
14 4C 72.28 BLL 20 09 52.3047264984 +72 29 19.351077612   19.0   19.40   ~ 127 1
15 6C 202345+760123 BLL 20 22 35.5757966424 +76 11 26.171152728     18.10 17.54   ~ 109 1
16 NAME Cepheus Region reg 21 20 00.0 +72 30 00           ~ 126 0
17 NAME Local Arm reg ~ ~           ~ 649 0
18 NAME Gould Belt PoG ~ ~           ~ 956 1

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