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Title: Gamma-ray follow-up studies on η Carinae

Abstract

Observations of high-energy γ-rays recently revealed a persistent source in spatial coincidence with the binary system η Carinae. Since modulation of the observed γ-ray flux on orbital time scales has not been reported so far, an unambiguous identification was hitherto not possible. In particular, the observations made by the Fermi Large Area Telescope (LAT) posed additional questions regarding the actual emission scenario. Analyses show two energetically distinct components in the γ-ray spectrum, which are best described by an exponentially cutoff power-law function (CPL) at energies below 10 GeV and a power-law (PL) component dominant at higher energies. The increased exposure in conjunction with the improved instrumental response functions of the LAT now allow us to perform a more detailed investigation of location, spectral shape, and flux time history of the observed γ-ray emission. Furthermore, we detect a weak but regular flux decrease over time. This can be understood and interpreted in a colliding-wind binary scenario for orbital modulation of the γ-ray emission. We find that the spectral shape of the γ-ray signal agrees with a single emitting particle population in combination with significant absorption by γ-γ pair production. We are able to report on the first unambiguous detection of GeVmore » γ-ray emission from a colliding-wind massive star binary. By studying the correlation of the flux decrease with the orbital separation of the binary components allows us to predict the behaviour up to the next periastron passage in 2014.« less

Authors:
 [1];  [2];  [2];  [1];  [1];  [3]
  1. Leopold Franzens Univ. Innsbruck (Austria). Inst. of Astrophysics and Particle Physics and Inst. for Theoretical Physics
  2. Leopold Franzens Univ. Innsbruck (Austria). Inst. of Astrophysics and Particle Physics and Inst. for Theoretical Physics; Stanford Univ. and SLAC National Accelerator Lab., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology
  3. Hiroshima Univ. (Japan). Hiroshima Astrophysical Science Center
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
Fermi LAT Collaboration
OSTI Identifier:
1356685
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 544; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma rays: stars; stars: massive; binaries: general

Citation Formats

Reitberger, K., Reimer, O., Reimer, A., Werner, M., Egberts, K., and Takahashi, H. Gamma-ray follow-up studies on η Carinae. United States: N. p., 2012. Web. doi:10.1051/0004-6361/201219249.
Reitberger, K., Reimer, O., Reimer, A., Werner, M., Egberts, K., & Takahashi, H. Gamma-ray follow-up studies on η Carinae. United States. doi:10.1051/0004-6361/201219249.
Reitberger, K., Reimer, O., Reimer, A., Werner, M., Egberts, K., and Takahashi, H. Wed . "Gamma-ray follow-up studies on η Carinae". United States. doi:10.1051/0004-6361/201219249. https://www.osti.gov/servlets/purl/1356685.
@article{osti_1356685,
title = {Gamma-ray follow-up studies on η Carinae},
author = {Reitberger, K. and Reimer, O. and Reimer, A. and Werner, M. and Egberts, K. and Takahashi, H.},
abstractNote = {Observations of high-energy γ-rays recently revealed a persistent source in spatial coincidence with the binary system η Carinae. Since modulation of the observed γ-ray flux on orbital time scales has not been reported so far, an unambiguous identification was hitherto not possible. In particular, the observations made by the Fermi Large Area Telescope (LAT) posed additional questions regarding the actual emission scenario. Analyses show two energetically distinct components in the γ-ray spectrum, which are best described by an exponentially cutoff power-law function (CPL) at energies below 10 GeV and a power-law (PL) component dominant at higher energies. The increased exposure in conjunction with the improved instrumental response functions of the LAT now allow us to perform a more detailed investigation of location, spectral shape, and flux time history of the observed γ-ray emission. Furthermore, we detect a weak but regular flux decrease over time. This can be understood and interpreted in a colliding-wind binary scenario for orbital modulation of the γ-ray emission. We find that the spectral shape of the γ-ray signal agrees with a single emitting particle population in combination with significant absorption by γ-γ pair production. We are able to report on the first unambiguous detection of GeV γ-ray emission from a colliding-wind massive star binary. By studying the correlation of the flux decrease with the orbital separation of the binary components allows us to predict the behaviour up to the next periastron passage in 2014.},
doi = {10.1051/0004-6361/201219249},
journal = {Astronomy and Astrophysics},
number = ,
volume = 544,
place = {United States},
year = {2012},
month = {8}
}

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Works referenced in this record:

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journal, May 2011


HESS observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae: HESS observations of the Carina nebula
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X‐Ray Spectral Variation of η Carinae through the 2003 X‐Ray Minimum
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FERMI LARGE AREA TELESCOPE OBSERVATION OF A GAMMA-RAY SOURCE AT THE POSITION OF ETA CARINAE
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Detection of Gamma-Ray Emission from the Eta-Carinae Region
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In hot pursuit of the hidden companion of η  Carinae: An X-ray determination of the wind parameters
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η Carinae: a very large hadron collider
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On the Nature of the Central Source in η Carinae
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The periodicity of the η Carinae events
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X-Ray Monitoring of η Carinae: Variations on a Theme
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Hard X-ray emission from η Carinae
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The Purple Haze of η Carinae: Binary-induced Variability?
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Super-Hard X-Ray Emission from η Carinae Observed with Suzaku
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    Works referencing / citing this record:

    Particle Acceleration in the Expanding Blast wave of η Carina'S Great Eruption of 1843
    journal, July 2010


    X-Ray Monitoring of η Carinae: Variations on a Theme
    journal, April 2005

    • Corcoran, M. F.
    • The Astronomical Journal, Vol. 129, Issue 4
    • DOI: 10.1086/428756

    Particle acceleration and nonthermal radio emission in binaries of early-type stars
    journal, January 1993

    • Eichler, D.; Usov, V.
    • The Astrophysical Journal, Vol. 402
    • DOI: 10.1086/172130

    The Likelihood Analysis of EGRET Data
    journal, April 1996

    • Mattox, J. R.; Bertsch, D. L.; Chiang, J.
    • The Astrophysical Journal, Vol. 461
    • DOI: 10.1086/177068

    The Purple Haze of η Carinae: Binary-induced Variability?
    journal, July 2004

    • Smith, Nathan; Morse, Jon A.; Collins, Nicholas R.
    • The Astrophysical Journal, Vol. 610, Issue 2
    • DOI: 10.1086/423341

    Hard X-ray emission from η Carinae
    journal, December 2007


    The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D
    journal, May 2005

    • Verner, E.; Bruhweiler, F.; Gull, T.
    • The Astrophysical Journal, Vol. 624, Issue 2
    • DOI: 10.1086/429400

    FERMI LARGE AREA TELESCOPE OBSERVATION OF A GAMMA-RAY SOURCE AT THE POSITION OF ETA CARINAE
    journal, October 2010


    THE CHANDRA CARINA COMPLEX PROJECT: DECIPHERING THE ENIGMA OF CARINA'S DIFFUSE X-RAY EMISSION
    journal, April 2011

    • Townsley, Leisa K.; Broos, Patrick S.; Chu, You-Hua
    • The Astrophysical Journal Supplement Series, Vol. 194, Issue 1
    • DOI: 10.1088/0067-0049/194/1/15

    FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG
    journal, May 2010

    • Abdo, A. A.; Ackermann, M.; Ajello, M.
    • The Astrophysical Journal Supplement Series, Vol. 188, Issue 2
    • DOI: 10.1088/0067-0049/188/2/405

    Super-Hard X-Ray Emission from η Carinae Observed with Suzaku
    journal, August 2009

    • Sekiguchi, Akiko; Tsujimoto, Masahiro; Kitamoto, Shunji
    • Publications of the Astronomical Society of Japan, Vol. 61, Issue 4
    • DOI: 10.1093/pasj/61.4.629

    X‐Ray Spectral Variation of η Carinae through the 2003 X‐Ray Minimum
    journal, July 2007

    • Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore
    • The Astrophysical Journal, Vol. 663, Issue 1
    • DOI: 10.1086/518101

    On the Nature of the Central Source in η Carinae
    journal, June 2001

    • Hillier, D. John; Davidson, K.; Ishibashi, K.
    • The Astrophysical Journal, Vol. 553, Issue 2
    • DOI: 10.1086/320948

    3D modelling of the colliding winds in η Carinae - evidence for radiative inhibition
    journal, April 2009


    η Carinae: a very large hadron collider
    journal, December 2010


    Opacity of the Universe to High-Energy Photons
    journal, March 1967


    Discovery of Very High Energy Gamma Rays Associated with an X-ray Binary
    journal, July 2005


    FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG
    journal, March 2012

    • Nolan, P. L.; Abdo, A. A.; Ackermann, M.
    • The Astrophysical Journal Supplement Series, Vol. 199, Issue 2
    • DOI: 10.1088/0067-0049/199/2/31

    HESS observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae: HESS observations of the Carina nebula
    journal, June 2012


    In hot pursuit of the hidden companion of η  Carinae: An X-ray determination of the wind parameters
    journal, February 2002


    High-energy radiation from the massive binary system Eta Carinae
    journal, May 2011


    The X‐Ray Light Curve of η Carinae: Refinement of the Orbit and Evidence for Phase‐dependent Mass Loss
    journal, February 2001

    • Corcoran, M. F.; Ishibashi, K.; Swank, J. H.
    • The Astrophysical Journal, Vol. 547, Issue 2
    • DOI: 10.1086/318416

    Radio emission models of colliding-wind binary systems
    journal, October 2003


    The periodicity of the η Carinae events
    journal, March 2008


    Detection of Gamma-Ray Emission from the Eta-Carinae Region
    journal, June 2009


    Chemical evolution of galaxies I. A composition-dependent SPH model for chemical evolution and cooling
    journal, July 2008

    • Martnez-Serrano, F. J.; Serna, A.; Domnguez-Tenreiro, R.
    • Monthly Notices of the Royal Astronomical Society, Vol. 388, Issue 1
    • DOI: 10.1111/j.1365-2966.2008.13383.x

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