2005A&A...442..895A

Query : 2005A&A...442..895A

2005A&A...442..895A - Astronomy and Astrophysics, volume 442895-907 (2005/11-2)

Multi-wavelength observations of PKS 2155-304 with HESS.

AHARONIAN F., AKHPERJANIAN A.G., BAZER-BACHI A.R., BEILICKE M., BENBOW W., BERGE D., BERNLOEHR K., BOISSON C., BOLZ O., BORREL V., BRAUN I., BREITLING F., BROWN A.M., CHADWICK P.M., CHOUNET L.-M., CORNILS R., COSTAMANTE L., DEGRANGE B., DICKINSON H.J., DJANNATI-ATAIE A., DRURY L.O'C., DUBUS G., EMMANOULOPOULOS D., ESPIGAT P., FEINSTEIN F., FONTAINE G., FUCHS Y., FUNK S., GALLANT Y.A., GIEBELS B., GILLESSEN S., GLICENSTEIN J.F., GORET P., HADJICHRISTIDIS C., HAUSER M., HEINZELMANN G., HENRI G., HERMANN G., HINTON J.A., HOFMANN W., HOLLERAN M., HORNS D., JACHOLKOWSKA A., DE JAGER O.C., KHELIFI B., KOMIN N., KONOPELKO A., LATHAM I.J., LE GALLOU R., LEMIERE A., LEMOINE-GOUMARD M., LEROY N., LOHSE T., MARTIN J.M., MARTINEAU-HUYNH O., MARCOWITH A., MASTERSON C., McCOMB T.J.L., DE NAUROIS M., NOLAN S.J., NOUTSOS A., ORFORD K.J., OSBORNE J.L., OUCHRIF M., PANTER M., PELLETIER G., PITA S., PUEHLHOFER G., PUNCH M., RAUBENHEIMER B.C., RAUE M., RAUX J., RAYNER S.M., REIMER A., REIMER O., RIPKEN J., ROB L., ROLLAND L., ROWELL G., SAHAKIAN V., SAUGE L., SCHLENKER S., SCHLICKEISER R., SCHUSTER C., SCHWANKE U., SIEWERT M., SOL H., SPANGLER D., STEENKAMP R., STEGMANN C., TAVERNET J.-P., TERRIER R., THEORET C.G., TLUCZYKONT M., VASILEIADIS G., VENTER C., VINCENT P., VOELK H.J. and WAGNER S.J.

Abstract (from CDS):

The High Energy Stereoscopic System (HESS) has observed the high-frequency peaked BL Lac object PKS 2155-304 in 2003 between October 19 and November 26 in Very High Energy (VHE) γ-rays (E≥160GeV for these observations). Observations were carried out simultaneously with the Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer satellite (RXTE), the Robotic Optical Transient Search Experiment (ROTSE) and the Nancay decimetric radiotelescope (NRT). Intra-night variability is seen in the VHE band, the source being detected with a high significance on each night it was observed. Variability is also found in the X-ray and optical bands on kilosecond timescales, along with flux-dependent spectral changes in the X-rays. A transient X-ray event with a 1500s timescale is detected, making this the fastest X-ray flare seen in this object. No correlation can be established between the X-ray and the γ-ray fluxes, or any of the other wavebands, over the small range of observed variability. The average HESS spectrum shows a very soft power law shape with a photon index of 3.37±0.07_stat±0.10_sys. The energy outputs in the 2-10keV and in the VHE γ-ray range are found to be similar, with the X-rays and the optical fluxes at a level comparable to some of the lowest historical measurements, indicating that PKS 2155-304 was in a low or quiescent state during the observations. Both a leptonic and a hadronic model are used to derive source parameters from these observations. These parameters are found to be sensitive to the model of Extragalactic Background Light (EBL) that attenuates the VHE signal at this source's redshift (z=0.117).

Abstract Copyright: ∼

Journal keyword(s): galaxies: active - gamma rays: observations - X-rays: galaxies - radiation mechanisms: non thermal

Simbad objects: 7

Full paper

View the references in ADS

Number of rows : 7

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Sp type	#ref 1850 - 2026	#notes
1	PKS J0550-3216	BLL	05 50 40.5705144672	-32 16 16.484718648		16.07	15.5		~	424	1
2	Z 184-50	BLL	11 04 27.3140835504	+38 12 31.798495872		13.50	12.90	8.31	~	2841	1
3	RX J1428.5+4240	BLL	14 28 32.6090008440	+42 40 21.048123396		16.95	16.45	14.4	~	549	1
4	Z 225-7	BLL	16 53 52.21668403	+39 45 36.6088754	14.09	14.15	13.29	8.26	~	2304	2
5	QSO B1959+650	BLL	19 59 59.8520303688	+65 08 54.652536492			12.8	11.21	~	699	2
6	PKS J2009-4849	BLL	20 09 25.3903899240	-48 49 53.725051056		15.75	12.81	11.41	~	604	1
7	PKS J2158-3013	BLL	21 58 52.0652249880	-30 13 32.118447792		13.36	13.09	12.62	~	1829	1

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