Associating long-term γ-ray variability with the superorbital period of LS I + 61◦ 303
Markus Ackermann
,
Marco Ajello
,
Jean Ballet
(1)
,
Guido Barbiellini
,
D. Bastieri
,
R. Bellazzini
,
E. Bonamente
,
T. J. Brandt
(2)
,
J. Bregeon
,
M. Brigida
,
Pascal Bruel
(3)
,
R. Buehler
,
S. Buson
,
G. A. Caliandro
,
R. A. Cameron
,
P. A. Caraveo
,
J. M. Casandjian
(1)
,
E. Cavazzuti
,
C. Cecchi
,
A. Chekhtman
,
J. Chiang
,
G. Chiaro
,
S. Ciprini
,
R. Claus
,
J. Cohen-Tanugi
,
L. R. Cominsky
,
J. Conrad
,
S. Cutini
,
M. Dalton
,
F. d'Ammando
,
A. de Angelis
,
P. R. den Hartog
,
F. de Palma
,
C. D. Dermer
,
S. W. Digel
,
L. Di Venere
,
P. S. Drell
,
R. Dubois
,
C. Favuzzi
,
S. J. Fegan
(3)
,
E. C. Ferrara
,
W. B. Focke
,
A. Franckowiak
,
S. Funk
,
P. Fusco
(4)
,
F. Gargano
(4)
,
D. Gasparrini
,
S. Germani
,
N. Giglietto
,
F. Giordano
,
M. Giroletti
,
T. Glanzman
,
G. Godfrey
,
I. A. Grenier
(1)
,
S. Guiriec
,
D. Hadasch
(5)
,
Y. Hanabata
,
A. K. Harding
,
M. Hayashida
,
E. Hays
,
A. B. Hill
(6)
,
D. Horan
(3)
,
R. E. Hughes
,
T. Jogler
,
G. J ́ohannesson
,
A.S. Johnson
,
T. J. Johnson
,
T. Kawano
,
M. Kerr
,
J. Kn ̈odlseder
,
M. Kuss
,
J. Lande
,
S. Larsson
,
L. Latronico
,
M. Lemoine-Goumard
(7)
,
J. Li
,
F. Longo
,
M. N. Lovellette
,
P. Lubrano
,
M. Mayer
,
M. N. Mazziotta
,
J. E. Mcenery
,
P. F. Michelson
,
T. Mizuno
,
M. E. Monzani
,
A. Morselli
,
I. V. Moskalenko
,
S. Murgia
,
R. Nemmen
,
E. Nuss
(8)
,
T. Ohsugi
,
A. Okumura
,
M. Orienti
,
E. Orlando
,
J. F. Ormes
,
D. Paneque
,
A. Papitto
,
J. S. Perkins
,
M. Pesce-Rollins
,
F. Piron
(8)
,
G. Pivato
,
S. Rain'O
,
R. Rando
,
M. Razzano
,
N. Rea
,
A. Reimer
,
O. Reimer
,
J. D. Scargle
,
A. Schulz
,
C. Sgr'O
,
E. J. Siskind
,
G. Spandre
,
P. Spinelli
,
H. Takahashi
,
J. G. Thayer
,
J. B. Thayer
,
M. Tinivella
,
D. F. Torres
,
G. Tosti
,
E. Troja
,
Y. Uchiyama
,
T. L. Usher
,
J. Vandenbroucke
,
V. Vasileiou
(8)
,
G. Vianello
,
V. Vitale
,
M. Werner
,
B. L. Winer
,
K. S. Wood
1
AIM (UMR7158 / UMR_E_9005 / UM_112) -
Astrophysique Interprétation Modélisation
2 IRAP - Institut de recherche en astrophysique et planétologie
3 LLR - Laboratoire Leprince-Ringuet
4 INFN, sezione di Bari - Istituto Nazionale di Fisica Nucleare, sezione di Bari
5 IEEC-CSIC
6 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
7 FERMI
8 LUPM - Laboratoire Univers et Particules de Montpellier
2 IRAP - Institut de recherche en astrophysique et planétologie
3 LLR - Laboratoire Leprince-Ringuet
4 INFN, sezione di Bari - Istituto Nazionale di Fisica Nucleare, sezione di Bari
5 IEEC-CSIC
6 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
7 FERMI
8 LUPM - Laboratoire Univers et Particules de Montpellier
Markus Ackermann
- Function : Author
Marco Ajello
- Function : Author
Guido Barbiellini
- Function : Author
D. Bastieri
- Function : Author
R. Bellazzini
- Function : Author
E. Bonamente
- Function : Author
J. Bregeon
- Function : Author
- PersonId : 741214
- IdHAL : johan-bregeon
- ORCID : 0000-0002-6790-5328
- IdRef : 095856943
M. Brigida
- Function : Author
R. Buehler
- Function : Author
S. Buson
- Function : Author
G. A. Caliandro
- Function : Author
R. A. Cameron
- Function : Author
P. A. Caraveo
- Function : Author
E. Cavazzuti
- Function : Author
C. Cecchi
- Function : Author
A. Chekhtman
- Function : Author
J. Chiang
- Function : Author
G. Chiaro
- Function : Author
S. Ciprini
- Function : Author
R. Claus
- Function : Author
J. Cohen-Tanugi
- Function : Author
- PersonId : 3626
- IdHAL : johann-cohen-tanugi
- ORCID : 0000-0001-9022-4232
- IdRef : 172626544
L. R. Cominsky
- Function : Author
J. Conrad
- Function : Author
S. Cutini
- Function : Author
M. Dalton
- Function : Author
F. d'Ammando
- Function : Author
A. de Angelis
- Function : Author
P. R. den Hartog
- Function : Author
F. de Palma
- Function : Author
C. D. Dermer
- Function : Author
S. W. Digel
- Function : Author
L. Di Venere
- Function : Author
- PersonId : 769090
- ORCID : 0000-0003-0703-824X
P. S. Drell
- Function : Author
R. Dubois
- Function : Author
C. Favuzzi
- Function : Author
S. J. Fegan
- Function : Author
- PersonId : 740343
- IdHAL : stephen-fegan
- ORCID : 0000-0002-9978-2510
- IdRef : 253133149
E. C. Ferrara
- Function : Author
W. B. Focke
- Function : Author
A. Franckowiak
- Function : Author
S. Funk
- Function : Author
D. Gasparrini
- Function : Author
S. Germani
- Function : Author
N. Giglietto
- Function : Author
- PersonId : 755413
- ORCID : 0000-0002-9021-2888
F. Giordano
- Function : Author
M. Giroletti
- Function : Author
T. Glanzman
- Function : Author
G. Godfrey
- Function : Author
S. Guiriec
- Function : Author
Y. Hanabata
- Function : Author
A. K. Harding
- Function : Author
M. Hayashida
- Function : Author
E. Hays
- Function : Author
R. E. Hughes
- Function : Author
T. Jogler
- Function : Author
G. J ́ohannesson
- Function : Author
A.S. Johnson
- Function : Author
T. J. Johnson
- Function : Author
T. Kawano
- Function : Author
- PersonId : 757520
- ORCID : 0000-0002-6876-9399
- IdRef : 156959658
M. Kerr
- Function : Author
J. Kn ̈odlseder
- Function : Author
M. Kuss
- Function : Author
J. Lande
- Function : Author
S. Larsson
- Function : Author
L. Latronico
- Function : Author
M. Lemoine-Goumard
- Function : Author
- PersonId : 1416454
- IdHAL : marianne-lemoine-goumard
- IdRef : 111693608
J. Li
- Function : Author
F. Longo
- Function : Author
- PersonId : 755442
- ORCID : 0000-0003-2501-2270
M. N. Lovellette
- Function : Author
P. Lubrano
- Function : Author
M. Mayer
- Function : Author
M. N. Mazziotta
- Function : Author
J. E. Mcenery
- Function : Author
P. F. Michelson
- Function : Author
T. Mizuno
- Function : Author
M. E. Monzani
- Function : Author
A. Morselli
- Function : Author
I. V. Moskalenko
- Function : Author
S. Murgia
- Function : Author
R. Nemmen
- Function : Author
T. Ohsugi
- Function : Author
A. Okumura
- Function : Author
M. Orienti
- Function : Author
E. Orlando
- Function : Author
J. F. Ormes
- Function : Author
D. Paneque
- Function : Author
- PersonId : 755279
- ORCID : 0000-0002-2830-0502
A. Papitto
- Function : Author
J. S. Perkins
- Function : Author
M. Pesce-Rollins
- Function : Author
- PersonId : 760585
- ORCID : 0000-0003-1790-8018
F. Piron
- Function : Author
- PersonId : 172749
- IdHAL : frederic-piron
- ORCID : 0000-0001-6885-7156
G. Pivato
- Function : Author
S. Rain'O
- Function : Author
R. Rando
- Function : Author
M. Razzano
- Function : Author
N. Rea
- Function : Author
A. Reimer
- Function : Author
- PersonId : 755465
- ORCID : 0000-0001-8604-7077
O. Reimer
- Function : Author
J. D. Scargle
- Function : Author
A. Schulz
- Function : Author
C. Sgr'O
- Function : Author
E. J. Siskind
- Function : Author
G. Spandre
- Function : Author
P. Spinelli
- Function : Author
H. Takahashi
- Function : Author
J. G. Thayer
- Function : Author
J. B. Thayer
- Function : Author
M. Tinivella
- Function : Author
D. F. Torres
- Function : Author
G. Tosti
- Function : Author
E. Troja
- Function : Author
Y. Uchiyama
- Function : Author
T. L. Usher
- Function : Author
J. Vandenbroucke
- Function : Author
G. Vianello
- Function : Author
V. Vitale
- Function : Author
- PersonId : 760184
- ORCID : 0000-0001-8040-7852
M. Werner
- Function : Author
- PersonId : 755168
- ORCID : 0000-0002-6473-0243
B. L. Winer
- Function : Author
K. S. Wood
- Function : Author
Abstract
Gamma-ray binaries are stellar systems for which the spectral ene rgy distribu- tion (discounting the thermal stellar emission) peaks at high energie s. Detected from radio to TeV gamma rays, the γ -ray binary LS I +61 ◦ 303 is highly variable across all frequencies. One aspect of this system's variability is the modula- tion of its emission with the timescale set by the ∼ 26 . 4960-day orbital period. Here we show that, during the time of our observations, the γ -ray emission of LS I +61 ◦ 303 also presents a sinusoidal variability consistent with the previou sly- known superorbital period of 1667 days. This modulation is more pro minently seen at orbital phases around apastron, whereas it does not intr oduce a visible change close to periastron. It is also found in the appearance and d isappearance of variability at the orbital period in the power spectrum of the data . This be- havior could be explained by a quasi-cyclical evolution of the equator ial outflow of the Be companion star, whose features influence the conditions for generating gamma rays. These findings open the possibility to use γ -ray observations to study the outflows of massive stars in eccentric binary systems.