The first full orbit of Eta Carinae seen by Fermi

Abstract

The binary system eta Carinae has completed its first 5.54y orbit since the beginning of science operation of the Fermi Large Area Telescope (LAT). We are now able to investigate the high-energy gamma-ray source at the position of eta Carinae over its full orbital period. By this, we can address and confirm earlier predictions for temporal and spectral variability. Newer versions of the LAT datasets, instrument response functions and background models allow for a more accurate analysis. Therefore it is important to re-evaluate the previously analyzed time period along with the new data to further constrain location, spectral shape, and flux time history of the gamma-ray source. We confirm earlier predictions of increasing flux values above 10 GeV toward the next periastron passage. For the most recent part of the data sample, flux values as high as those before the first periastron passage in 2008 are recorded. A comparison of spectral energy distributions around periastron and apastron passages reveals strong variation in the high-energy band. This is due to a second spectral component that is present only around periastron. Improved spatial consistency with the gamma-ray source at the position of eta Carinae along with the confirmation of temporal variability above 10 GeV in conjunction with the orbital period strengthens the argument for unambiguous source identification. Spectral variability provides additional constraints for future modeling of the particle acceleration and gamma-ray emission in colliding-wind binary systems.

6 pages, 3 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (6)

• Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140
• Detection of Gamma-ray Emission from the Eta-Carinae Region
• Hard X-ray emission from Eta Carinae
• Gamma-ray follow-up studies on Eta Carinae
• Simulating three-dimensional nonthermal high-energy photon emission in colliding-wind binaries
• Particle acceleration in the expanding blast wave of Eta Carina's Great Eruption of 1843

Cited by in corpus (20)

• Non-thermal X-rays from Colliding Wind Shock Acceleration in the Massive Binary Eta Carinae
• Modelling the interaction between relativistic and non-relativistic winds in binary pulsar systems: strong magnetization of the pulsar wind
• Particle acceleration and non-thermal emission in colliding-wind binary systems
• 3D magneto-hydrodynamic models of non-thermal photon emission in the binary system ${\gamma }^2$ Velorum
• Dense molecular gas at 12 mm towards Galactic TeV gamma-ray sources
• Eta Carinae with Fermi-LAT: Two full orbits and the third periastron
• A lepto-hadronic model of gamma rays from the Eta Carinae and prospects for neutrino telescopes
• Evidence for non-thermal X-ray emission from the double WR colliding-wind binary Apep
• Diffuse $\gamma$-ray emission around the massive star forming region of Carina Nebula Complex
• Investigation of the WR 11 field at decimeter wavelengths
• X-ray emission of massive stars and their winds
• The high-energy emission from HD~93129A near periastron
• $\eta$ Carinae: high angular resolution continuum, H30$\alpha$ and He30$\alpha$ ALMA images
• Probing the star formation origin of gamma rays from 3FHL J1907.0+0713
• Probing cosmic ray escape from η Carinae
• Detection of very-high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage
• On the orbital variability of gamma-ray emission in ${\gamma }^2$ Velorum
• Telluric absorption lines in the ALMA spectra of $\eta$ Car
• MHD Models of Gamma-ray Emission in WR 11
• Combined Magnetohydrodynamic- Monte Carlo Simulations of Proton Acceleration in Colliding Wind Binaries