2011ApJ...726...81A

Query : 2011ApJ...726...81A

2011ApJ...726...81A - Astrophys. J., 726, 81 (2011/January-2)

Constraints on the cosmic-ray density gradient beyond the solar circle from Fermi γ-ray observations of the third galactic quadrant.

ACKERMANN M., AJELLO M., BALDINI L., BALLET J., BARBIELLINI G., BASTIERI D., BECHTOL K., BELLAZZINI R., BERENJI B., BLOOM E.D., BONAMENTE E., BORGLAND A.W., BRANDT T.J., BREGEON J., BREZ A., BRIGIDA M., BRUEL P., BUEHLER R., 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., DERMER C.D., DE PALMA F., DIGEL S.W., DRELL P.S., DUBOIS R., FAVUZZI C., FERRARA E.C., FOCKE W.B., FUKAZAWA Y., FUNK S., FUSCO P., GARGANO F., GERMANI S., GIGLIETTO N., GIORDANO F., GIROLETTI M., GLANZMAN T., GODFREY G., GRENIER I.A., GUIRIEC S., HADASCH D., HANABATA Y., HARDING A.K., HAYASHI K., HAYASHIDA M., HUGHES R.E., ITOH R., JOHANNESSON G., JOHNSON A.S., JOHNSON W.N., KAMAE T., KATAGIRI H., KATAOKA J., KNODLSEDER J., KUSS M., LANDE J., LATRONICO L., LEE S.-H., GARDE M.L., LONGO F., LOPARCO F., LOVELLETTE M.N., LUBRANO P., MAKEEV A., MARTIN P., MAZZIOTTA M.N., McENERY J.E., MEHAULT J., MICHELSON P.F., MIZUNO T., MONTE C., MONZANI M.E., MORSELLI A., MOSKALENKO I.V., MURGIA S., NAUMANN-GODO M., NISHINO S., NOLAN P.L., NORRIS J.P., NUSS E., OHSUGI T., OKUMURA A., OMODEI N., ORLANDO E., ORMES J.F., OZAKI M., PARENT D., PELASSA V., PEPE M., PESCE-ROLLINS M., PIRON F., PORTER T.A., RAINO S., RANDO R., RAZZANO M., REIMER A., REIMER O., RIPKEN J., SADA T., SADROZINSKI H.F.-W., SGRO C., SISKIND E.J., SPANDRE G., SPINELLI P., STRICKMAN M.S., STRONG A.W., SUSON D.J., TAKAHASHI H., TAKAHASHI T., TANAKA T., THAYER J.B., THOMPSON D.J., TIBALDO L., TORRES D.F., TRAMACERE A., UCHIYAMA Y., UEHARA T., USHER T.L., VANDENBROUCKE J., VASILEIOU V., VILCHEZ N., VITALE V., VLADIMIROV A.E., WAITE A.P., WANG P., WOOD K.S., YANG Z. and ZIEGLER M.

Abstract (from CDS):

We report an analysis of the interstellar γ-ray emission in the third Galactic quadrant measured by the Fermi Large Area Telescope. The window encompassing the Galactic plane from longitude 210° to 250° has kinematically well-defined segments of the Local and the Perseus arms, suitable to study the cosmic-ray (CR) densities across the outer Galaxy. We measure no large gradient with Galactocentric distance of the γ-ray emissivities per interstellar H atom over the regions sampled in this study. The gradient depends, however, on the optical depth correction applied to derive the H I column densities. No significant variations are found in the interstellar spectra in the outer Galaxy, indicating similar shapes of the CR spectrum up to the Perseus arm for particles with GeV to tens of GeV energies. The emissivity as a function of Galactocentric radius does not show a large enhancement in the spiral arms with respect to the interarm region. The measured emissivity gradient is flatter than expectations based on a CR propagation model using the radial distribution of supernova remnants and uniform diffusion properties. In this context, observations require a larger halo size and/or a flatter CR source distribution than usually assumed. The molecular mass calibrating ratio, XCO= N(H2)/WCO, is found to be (2.08±0.11)x1020/cm2(K km/s)–1 in the Local arm clouds and is not significantly sensitive to the choice of H I spin temperature. No significant variations are found for clouds in the interarm region.

Abstract Copyright: ∼

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

Errata: erratum vol. 772, art. 154 (2013)

Simbad objects: 18

goto Full paper

goto View the references in ADS

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 NAME Per Arm PoG 03 30 +45.0           ~ 1672 0
2 NAME Mon R2 HII 06 07 47.58 -06 22 42.6           ~ 789 2
3 NAME Maddalena Cloud MoC 06 48.1 -03 52           ~ 100 0
4 NGC 2348 err 07 03 03 -67 24.7           ~ 11 0
5 Ass CMa OB 1 As* 07 07.0 -10 28           ~ 161 0
6 GRB 080916C gB 07 59 23.24 -56 38 16.8           ~ 386 0
7 NGC 2632 OpC 08 39 58.4 +19 36 33           ~ 1733 0
8 Fermi bn090902462 gB 17 39 45.26 +27 19 28.1           ~ 440 0
9 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
10 NAME Cepheus Region reg 21 20 00.0 +72 30 00           ~ 126 0
11 NAME Outer Arm PoG 21 48 +69.4           ~ 370 0
12 Fermi bn090510016 G 22 14 12.6230 -26 34 58.550           ~ 548 0
13 NGC 7538 OpC 23 13 37 +61 30.0           ~ 920 1
14 Fermi bn090926181 gB 23 33 36.18 -66 19 25.9           ~ 339 0
15 NAME Gould Belt PoG ~ ~           ~ 956 1
16 NAME Local Arm reg ~ ~           ~ 649 0
17 NAME Ori Mon Complex Cld ~ ~           ~ 19 0
18 Ass CMa OB 2 As* ~ ~           ~ 12 0

To bookmark this query, right click on this link: simbad:objects in 2011ApJ...726...81A and select 'bookmark this link' or equivalent in the popup menu