2016ApJ...826....1A

Query : 2016ApJ...826....1A

2016ApJ...826....1A - Astrophys. J., 826, 1-1 (2016/July-3)

Fermi large area telescope detection of extended gamma-ray emission from the radio galaxy Fornax A.

ACKERMANN M., AJELLO M., BALDINI L., BALLET J., BARBIELLINI G., BASTIERI D., BELLAZZINI R., BISSALDI E., BLANDFORD R.D., BLOOM E.D., BONINO R., BRANDT T.J., BREGEON J., BRUEL P., BUEHLER R., BUSON S., CALIANDRO G.A., CAMERON R.A., CARAGIULO M., CARAVEO P.A., CAVAZZUTI E., CECCHI C., CHARLES E., CHEKHTMAN A., CHEUNG C.C., CHIARO G., CIPRINI S., COHEN J.M., COHEN-TANUGI J., COSTANZA F., CUTINI S., D'AMMANDO F., DAVIS D.S., DE ANGELIS A., DE PALMA F., DESIANTE R., DIGEL S.W., DI LALLA N., DI MAURO M., DI VENERE L., FAVUZZI C., FEGAN S.J., FERRARA E.C., FOCKE W.B., FUKAZAWA Y., FUNK S., FUSCO P., GARGANO F., GASPARRINI D., GEORGANOPOULOS M., GIGLIETTO N., GIORDANO F., GIROLETTI M., GODFREY G., GREEN D., GRENIER I.A., GUIRIEC S., HAYS E., HEWITT J.W., HILL A.B., JOGLER T., JOHANNESSON G., KENSEI S., KUSS M., LARSSON S., LATRONICO L., LI J., LI L., LONGO F., LOPARCO F., LUBRANO P., MAGILL J.D., MALDERA S., MANFREDA A., MAYER M., MAZZIOTTA M.N., McCONVILLE W., McENERY J.E., MICHELSON P.F., MITTHUMSIRI W., MIZUNO T., MONZANI M.E., MORSELLI A., MOSKALENKO I.V., MURGIA S., NEGRO M., NUSS E., OHNO M., OHSUGI T., ORIENTI M., ORLANDO E., ORMES J.F., PANEQUE D., PERKINS J.S., PESCE-ROLLINS M., PIRON F., PIVATO G., PORTER T.A., RAINO S., RANDO R., RAZZANO M., REIMER A., REIMER O., SCHMID J., SGRO C., SIMONE D., SISKIND E.J., SPADA F., SPANDRE G., SPINELLI P., STAWARZ L., TAKAHASHI H., THAYER J.B., THOMPSON D.J., TORRES D.F., TOSTI G., TROJA E., VIANELLO G., WOOD K.S., WOOD M. and ZIMMER S.

Abstract (from CDS):

We report the Fermi Large Area Telescope detection of extended γ-ray emission from the lobes of the radio galaxy Fornax A using 6.1 years of Pass 8 data. After Centaurus A, this is now the second example of an extended γ-ray source attributed to a radio galaxy. Both an extended flat disk morphology and a morphology following the extended radio lobes were preferred over a point-source description, and the core contribution was constrained to be \lt 14 % of the total γ-ray flux. A preferred alignment of the γ-ray elongation with the radio lobes was demonstrated by rotating the radio lobes template. We found no significant evidence for variability on ∼0.5 year timescales. Taken together, these results strongly suggest a lobe origin for the γ-rays. With the extended nature of the \gt 100 MeV γ-ray emission established, we model the source broadband emission considering currently available total lobe radio and millimeter flux measurements, as well as X-ray detections attributed to inverse Compton (IC) emission off the cosmic microwave background (CMB). Unlike the Centaurus A case, we find that a leptonic model involving IC scattering of CMB and extragalactic background light (EBL) photons underpredicts the γ-ray fluxes by factors of about ∼2-3, depending on the EBL model adopted. An additional γ-ray spectral component is thus required, and could be due to hadronic emission arising from proton-proton collisions of cosmic rays with thermal plasma within the radio lobes.

Journal keyword(s): galaxies: active - galaxies: individual: Fornax A - galaxies: jets - gamma rays: galaxies - radiation mechanisms: non-thermal

Simbad objects: 5

Full paper

View the references in ADS

Number of rows : 5

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Sp type	#ref 1850 - 2026	#notes
1	NGC 1316	rG	03 22 41.789	-37 12 29.52	9.81	9.15	8.53	7.66	~	1491	1
2	ACO S 373	ClG	03 38 29.4	-35 27 08					~	2029	0
3	MCG-02-24-007	LIN	09 18 05.66848602	-12 05 43.8060823		14.38	14.8		~	1077	1
4	NAME Centaurus A	BLL	13 25 27.61521044	-43 01 08.8050291		8.18	6.84	6.66	~	4774	3
5	NGC 6251	Bla	16 32 31.96989253	+82 32 16.3999044	15.24	14.66	12.89	7.62	~	772	1

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