H.E.S.S. observations of PKS 2155-304

Aharonian, F.; Akhperjanian, A.G.; Aye, K.-M.; Bazer-Bachi, A.R.; Beilicke, M.; Benbow, W.; Berge, D.; Berghaus, P.; Bernlöhr, K.; Bolz, O.; Boisson, C.; Borgmeier, C.; Breitling, F.; Brown, A.M.; Bussons Gordo, J.; Chadwick, P.M.; Chitnis, V.R.; Chounet, L.-M.; Cornils, R.; Costamante, L.; Degrange, B.; Djannati-Ataï, A.; Drury, L. O'C.; Ergin, T.; Espigat, P.; Feinstein, F.; Fleury, P.; Fontaine, G.; Funk, S.; Gallant, Y.A.; Giebels, B.; Gillessen, S.; Goret, P.; Guy, J.; Hadjichristidis, C.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J.A.; Hofmann, W.; Holleran, M.; Horns, D.; de Jager, O.C.; Jung, I.; Khélifi, B.; Komin, N.; Konopelko, A.; Latham, I.J.; Le Gallou, R.; Lemoine, M.; Lemière, A.; Leroy, N.; Lohse, T.; 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.; Pohl, M.; Pühlhofer, G.; Punch, M.; Raubenheimer, B.C.; Raue, M.; Raux, J.; Rayner, S.M.; Redondo, I.; Reimer, A.; Reimer, O.; Ripken, J.; Rivoal, M.; Rob, L.; Rolland, L.; Rowell, G.; Sahakian, V.; Saugé, L.; Schlenker, S.; Schlickeiser, R.; Schuster, C.; Schwanke, U.; Siewert, M.; Sol, H.; Steenkamp, R.; Stegmann, C.; Tavernet, J.-P.; Théoret, C.G.; Tluczykont, M.; van der Walt, D.J.; Vasileiadis, G.; Vincent, P.; Visser, B.; Völk, H.J.; Wagner, S.J.

doi:10.1051/0004-6361:20041853

H.E.S.S. observations of PKS 2155-304

Aharonian, F.; Akhperjanian, A.G.; Aye, K.-M.; Bazer-Bachi, A.R.; Beilicke, M.; Benbow, W.; Berge, D.; Berghaus, P.; Bernlöhr, K.; Bolz, O.; Boisson, C.; Borgmeier, C.; Breitling, F.; Brown, A.M.; Bussons Gordo, J.; Chadwick, P.M.; Chitnis, V.R.; Chounet, L.-M.; Cornils, R.; Costamante, L.; Degrange, B.; Djannati-Ataï, A.; Drury, L. O'C.; Ergin, T.; Espigat, P.; Feinstein, F.; Fleury, P.; Fontaine, G.; Funk, S.; Gallant, Y.A.; Giebels, B.; Gillessen, S.; Goret, P.; Guy, J.; Hadjichristidis, C.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J.A.; Hofmann, W.; Holleran, M.; Horns, D.; de Jager, O.C.; Jung, I.; Khélifi, B.; Komin, N.; Konopelko, A.; Latham, I.J.; Le Gallou, R.; Lemoine, M.; Lemière, A.; Leroy, N.; Lohse, T.; 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.; Pohl, M.; Pühlhofer, G.; Punch, M.; Raubenheimer, B.C.; Raue, M.; Raux, J.; Rayner, S....

Authors

F. Aharonian

A.G. Akhperjanian

K.-M. Aye

A.R. Bazer-Bachi

M. Beilicke

W. Benbow

D. Berge

P. Berghaus

K. Bernlöhr

O. Bolz

C. Boisson

C. Borgmeier

F. Breitling

A.M. Brown

J. Bussons Gordo

Professor Paula Chadwick p.m.chadwick@durham.ac.uk
Head Of Department

V.R. Chitnis

L.-M. Chounet

R. Cornils

L. Costamante

B. Degrange

A. Djannati-Ataï

L. O'C. Drury

T. Ergin

P. Espigat

F. Feinstein

P. Fleury

G. Fontaine

S. Funk

Y.A. Gallant

B. Giebels

S. Gillessen

P. Goret

J. Guy

C. Hadjichristidis

M. Hauser

G. Heinzelmann

G. Henri

G. Hermann

J.A. Hinton

W. Hofmann

M. Holleran

D. Horns

O.C. de Jager

I. Jung

B. Khélifi

N. Komin

A. Konopelko

I.J. Latham

R. Le Gallou

M. Lemoine

A. Lemière

N. Leroy

T. Lohse

A. Marcowith

C. Masterson

T.J.L. McComb

M. de Naurois

Professor Sam Nolan s.j.nolan@durham.ac.uk
Director Of Dcad

A. Noutsos

K.J. Orford

Dr John Osborne j.l.osborne@durham.ac.uk
Emeritus

M. Ouchrif

M. Panter

G. Pelletier

S. Pita

M. Pohl

G. Pühlhofer

M. Punch

B.C. Raubenheimer

M. Raue

J. Raux

S.M. Rayner

I. Redondo

A. Reimer

O. Reimer

J. Ripken

M. Rivoal

L. Rob

L. Rolland

G. Rowell

V. Sahakian

L. Saugé

S. Schlenker

R. Schlickeiser

C. Schuster

U. Schwanke

M. Siewert

H. Sol

R. Steenkamp

C. Stegmann

J.-P. Tavernet

C.G. Théoret

M. Tluczykont

D.J. van der Walt

G. Vasileiadis

P. Vincent

B. Visser

H.J. Völk

S.J. Wagner

Abstract

The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.117 has been detected with high significance (~45sigma) at energies greater than 160 GeV, using the H.E.S.S. stereoscopic array of imaging air-Cherenkov telescopes in Namibia. A strong signal is found in each of the data sets corresponding to the dark periods of July and October, 2002, and June-September, 2003. The observed flux of VHE gamma rays shows variability on time scales of months, days, and hours. The monthly-averaged integral flux above 300 GeV varies between 10% and 60% of the flux observed from the Crab Nebula. Energy spectra are measured for these individual periods of data taking and are characterized by a steep power law with a time-averaged photon index of Gamma=3.32±0.06. An improved chi2 per degree of freedom is found when either a power law with an exponential cutoff energy or a broken power law are fit to the time-averaged energy spectrum. However, the significance of the improvement is marginal (~2sigma). The suggested presence of features in the energy spectrum may be intrinsic to the emission from the blazar, or an indication of absorption of TeV gamma rays by the extragalactic infrared background light

Citation

Aharonian, F., Akhperjanian, A., Aye, K., Bazer-Bachi, A., Beilicke, M., Benbow, W., …Wagner, S. (2005). H.E.S.S. observations of PKS 2155-304. Astronomy & Astrophysics, 430(3), 865-875. https://doi.org/10.1051/0004-6361%3A20041853

Journal Article Type	Article
Publication Date	Feb 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	430
Issue	3
Pages	865-875
DOI	https://doi.org/10.1051/0004-6361%3A20041853
Keywords	Active galaxies, BL Lacertae objects, Gamma rays.
Public URL	https://durham-repository.worktribe.com/output/1578547