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Multi-wavelength observations of PKS 2155-304 with HESS

Aharonian, F.; Akhperjanian, A.G.; Bazer-Bachi, A.R.; Beilicke, M.; Benbow, W.; Berge, D.; Bernlöhr, 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-Ataï, 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.; Khélifi, B.; Komin, N.; Konopelko, A.; Latham, I.J.; Le Gallou, R.; Lemière, 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.; Pühlhofer, G.; Punch, M.; Raubenheimer,...

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


Authors

F. Aharonian

A.G. Akhperjanian

A.R. Bazer-Bachi

M. Beilicke

W. Benbow

D. Berge

K. Bernlöhr

C. Boisson

O. Bolz

V. Borrel

I. Braun

F. Breitling

A.M. Brown

L.-M. Chounet

R. Cornils

L. Costamante

B. Degrange

H.J. Dickinson

A. Djannati-Ataï

L. O'C. Drury

G. Dubus

D. Emmanoulopoulos

P. Espigat

F. Feinstein

G. Fontaine

Y. Fuchs

S. Funk

Y.A. Gallant

B. Giebels

S. Gillessen

J.F. Glicenstein

P. Goret

C. Hadjichristidis

M. Hauser

G. Heinzelmann

G. Henri

G. Hermann

J.A. Hinton

W. Hofmann

M. Holleran

D. Horns

A. Jacholkowska

O.C. de Jager

B. Khélifi

N. Komin

A. Konopelko

I.J. Latham

R. Le Gallou

A. Lemière

M. Lemoine-Goumard

N. Leroy

T. Lohse

J.M. Martin

O. Martineau-Huynh

A. Marcowith

C. Masterson

T.J.L. McComb

M. de Naurois

S.J. Nolan

A. Noutsos

K.J. Orford

M. Ouchrif

M. Panter

G. Pelletier

S. Pita

G. Pühlhofer

M. Punch

B.C. Raubenheimer

M. Raue

J. Raux

S.M. Rayner

A. Reimer

O. Reimer

J. Ripken

L. Rob

L. Rolland

G. Rowell

V. Sahakian

L. Saugé

S. Schlenker

R. Schlickeiser

C. Schuster

U. Schwanke

M. Siewert

H. Sol

D. Spangler

R. Steenkamp

C. Stegmann

J.-P. Tavernet

R. Terrier

C.G. Théoret

M. Tluczykont

G. Vasileiadis

C. Venter

P. Vincent

H.J. Völk

S. Wagner



Abstract

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) gamma-rays (E >= 160 GeV 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 1500 s 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 gamma-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 - 10 keV and in the VHE gamma-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).

Citation

Aharonian, F., Akhperjanian, A., Bazer-Bachi, A., Beilicke, M., Benbow, W., Berge, D., …Wagner, S. (2005). Multi-wavelength observations of PKS 2155-304 with HESS. Astronomy & Astrophysics, 442(3), 895-907. https://doi.org/10.1051/0004-6361%3A20053353

Journal Article Type Article
Publication Date Nov 1, 2005
Deposit Date May 29, 2008
Publicly Available Date May 29, 2008
Journal Astronomy and astrophysics.
Print ISSN 0004-6361
Electronic ISSN 1432-0746
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 442
Issue 3
Pages 895-907
DOI https://doi.org/10.1051/0004-6361%3A20053353
Keywords Active galaxies, Energy gamma Rays, Observations, X-rays, Radiation mechanisms, Non thermal, BL-LAC objects, Atmospheric Cherenkov telescopes, Synchrotron-proton blazar, Active galactic nuclei, Simultaneous x-ray, Tev blazars, Spectral variability.

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Copyright Statement
Reproduced with permission from Astronomy & Astrophysics, © ESO





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