2015MNRAS.450.4399A

Query : 2015MNRAS.450.4399A

2015MNRAS.450.4399A - Mon. Not. R. Astron. Soc., 450, 4399-4410 (2015/July-2)

Probing the very high energy γ-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes.

ALEKSIC J., ANSOLDI S., ANTONELLI L.A., ANTORANZ P., BABIC A., BANGALE P., BARRIO J.A., BECERRA GONZALEZ J., BEDNAREK W., BERNARDINI E., BIASUZZI B., BILAND A., BLANCH O., BONNEFOY S., BONNOLI G., BORRACCI F., BRETZ T., CARMONA E., CAROSI A., COLIN P., COLOMBO E., CONTRERAS J.L., CORTINA J., COVINO S., DA VELA P., DAZZI F., DE ANGELIS A., DE CANEVA G., DE LOTTO B., DE ONA WILHELMI E., DELGADO MENDEZ C., DOMINIS PRESTER D., DORNER D., DORO M., EINECKE S., EISENACHER D., ELSAESSER D., FIDALGO D., FONSECA M.V., FONT L., FRANTZEN K., FRUCK C., GALINDO D., GARCIA LOPEZ R.J., GARCZARCZYK M., GARRIDO TERRATS D., GAUG M., GODINOVIC N., GONZALEZ MUNOZ A., GOZZINI S.R., HADASCH D., HANABATA Y., HAYASHIDA M., HERRERA J., HILDEBRAND D., HOSE J., HRUPEC D., IDEC W., KADENIUS V., KELLERMANN H., KNOETIG M.L., KODANI K., KONNO Y., KRAUSE J., KUBO H., KUSHIDA J., LA BARBERA A., LELAS D., LEWANDOWSKA N., LINDFORS E., LOMBARDI S., LONGO F., LOPEZ M., LOPEZ-COTO R., LOPEZ-ORAMAS A., LORENZ E., LOZANO I., MAKARIEV M., MALLOT K., MANEVA G., MANNHEIM K., MARASCHI L., MARCOTE B., MARIOTTI M., MARTINEZ M., MAZIN D., MENZEL U., MIRANDA J.M., MIRZOYAN R., MORALEJO A., MUNAR-ADROVER P., NAKAJIMA D., NEUSTROEV V., NIEDZWIECKI A., NILSSON K., NISHIJIMA K., NODA K., ORITO R., OVERKEMPING A., PAIANO S., PALATIELLO M., PANEQUE D., PAOLETTI R., PAREDES J.M., PAREDES-FORTUNY X., PERSIC M., POUTANEN J., PRADA MORONI P.G., PRANDINI E., PULJAK I., REINTHAL R., RHODE W., RIBO M., RICO J., RODRIGUEZ GARCIA J., RUGAMER S., SAITO T., SAITO K., SATALECKA K., SCALZOTTO V., SCAPIN V., SCHULTZ C., SCHWEIZER T., SILLANPAA A., SITAREK J., SNIDARIC I., SOBCZYNSKA D., SPANIER F., STAMERRA A., STEINBRING T., STORZ J., STRZYS M., TAKALO L., TAKAMI H., TAVECCHIO F., TEMNIKOV P., TERZIC T., TESCARO D., TESHIMA M., THAELE J., TIBOLLA O., TORRES D.F., TOYAMA T., TREVES A., VOGLER P., WILL M., ZANIN R. (The MAGIC Collaboration), D'AMMANDO F., BUSON S. (The Fermi-LAT Collaboration), LAHTEENMAKI A., TORNIKOSKI M., HOVATTA T., READHEAD A.C.S., MAX-MOERBECK W. and RICHARDS J.L.

Abstract (from CDS):

PG 1553+113 is a very high energy (VHE, E > 100GeV) γ-ray emitter classified as a BL Lac object. Its redshift is constrained by intergalactic absorption lines in the range 0.4 < z < 0.58. The MAGIC telescopes have monitored the source's activity since 2005. In early 2012, PG 1553+113 was found in a high state, and later, in April of the same year, the source reached its highest VHE flux state detected so far. Simultaneous observations carried out in X-rays during 2012 April show similar flaring behaviour. In contrast, the γ-ray flux at E < 100GeV observed by Fermi-LAT is compatible with steady emission. In this paper, a detailed study of the flaring state is presented. The VHE spectrum shows clear curvature, being well fitted either by a power law with an exponential cut-off or by a log-parabola. A simple power-law fit hypothesis for the observed shape of the PG 1553+113 VHE γ-ray spectrum is rejected with a high significance (fit probability P = 2.6x10–6). The observed curvature is compatible with the extragalactic background light (EBL) imprint predicted by current generation EBL models assuming a redshift z ∼ 0.4. New constraints on the redshift are derived from the VHE spectrum. These constraints are compatible with previous limits and suggest that the source is most likely located around the optical lower limit, z = 0.4, based on the detection of Lyα absorption. Finally, we find that the synchrotron self-Compton model gives a satisfactory description of the observed multiwavelength spectral energy distribution during the flare.

Abstract Copyright: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)

Journal keyword(s): galaxies: active - BL Lacertae objects: general - BL Lacertae objects: individual: PG1553+113 - cosmic background radiation - gamma-rays: galaxies - gamma-rays: general

Simbad objects: 6

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Number of rows : 6
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 M 1 SNR 05 34 31.8 +22 01 03           ~ 6516 1
2 3C 286 Sy1 13 31 08.2883506368 +30 30 32.960091564   17.51 17.25     ~ 4558 2
3 QSO B1502+1041 Bla 15 04 24.97978391 +10 29 39.1985309   18.97 18.56 18.94   ~ 634 1
4 QSO B1551+130 Bla 15 53 32.6978115648 +12 56 51.713513052   18.05 17.65 17.1   ~ 182 1
5 PG 1553+113 BLL 15 55 43.0440048528 +11 11 24.365649948 14.91 14.72 14.57 13.99   ~ 672 1
6 4C 10.45 Bla 16 08 46.20318700 +10 29 07.7757424   18.5 18.70 18.03   ~ 409 1

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