Constraints on Extragalactic Background Light using TeV Observations of BL Lacertae objects

Abstract

The extragalactic background light (EBL) in the IR to UV bands partly absorbs very high energy (VHE, $E\ge$ 100GeV) $\gamma -$ray photons travelling over cosmological distances via pair production. In this paper, to get stronger constraints on EBL, we use the deliberate selection of the EBL model and data of five BL Lacs with better statistics and the harder spectra to limit the EBL density and the radiation mechanism of BL Lacs. We constrain the upper limit of the EBL density by fitting the spectral energy distributions (SEDs) of TeV BL Lacs and find that our results are compatible with the published measurement, reaching 50 $\mathrm{nW}{\mathrm{m}}^{-2}\mathrm{s}{\mathrm{r}}^{-1}$. We also obtain that the EBL is not necessarily transparent to high VHE photons. We fix the intrinsic spectral index ${\Gamma }_i$ of TeV BL Lacs as 1.0 and 1.5 under observation evidence and model assumption. Comparing the EBL density given by galaxy count and $Spitzer$ observations, we then obtain that 1ES 1101-232 has ${\Gamma }_i$ $\le$ 1.0 and 1ES 0229+200 should have ${\Gamma }_i$ not harder than 1.0. We demonstrate that the common radiation assumption of BL Lacs, in which the ${\Gamma }_i$ is softer than 1.5, should be revisited. Furthermore, we propose that the upper EBL density could be given by fitting the hardest energy spectra of TeV BL Lacs.

arXiv commentAccepted by MNRAS

References in corpus (43)

• emcee: The MCMC Hammer
• Cosmological parameters from CMB and other data: a Monte-Carlo approach
• The extragalactic optical-infrared background radiations, their time evolution and the cosmic photon-photon opacity
• The Cosmic Infrared Background: Measurements and Implications
• Extragalactic Background Light Inferred from AEGIS Galaxy SED-type Fractions
• The COBE Diffuse Infrared Background Experiment Search for the Cosmic Infrared Background: I. Limits and Detections
• A low level of extragalactic background light as revealed by gamma-rays from blazars
• Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra
• Deep Galaxy Counts, Extragalactic Background Light, and the Stellar Baryon Budget
• Number Counts At 3 < lambda < 10 um From the Spitzer Space Telescope
• New constraints on the Mid-IR EBL from the HESS discovery of VHE gamma rays from 1ES 0229+200
• The Extragalactic Background Light and the Gamma-ray Opacity of the Universe
• New limits on the density of the extragalactic background light in the optical to the far-infrared from the spectra of all known TeV blazars
• The extragalactic background light, the Hubble constant, and anomalies: conclusions from 20 years of TeV gamma-ray observations
• Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S
• A $\gamma$-ray determination of the Universe's star-formation history
• Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars
• Radiation Mechanisms and Physical Properties of GeV-TeV BL Lac Objects
• An observational determination of the evolving extragalactic background light from the multiwavelength HST/CANDELS survey in the Fermi and CTA era
• Simultaneous Constraints on the Spectrum of the Extragalactic Background Light and the Intrinsic Tev Spectra of Mrk 421, Mrk 501, and H1426+428
• Hard TeV spectra of blazars and the constraints to the IR intergalactic background
• Detection of the cosmic γ-ray horizon from multiwavelength observations of blazars
• Evidence for GeV Pair Halos around Low Redshift Blazars
• Measurement of the Extragalactic Background Light using MAGIC and Fermi-LAT gamma-ray observations of blazars up to z = 1
• Stochastic conversions of TeV photons into axion-like particles in extragalactic magnetic fields
• The second catalog of flaring gamma-ray sources from the Fermi All-sky Variability Analysis
• A new measurement of the Hubble constant and matter content of the Universe using extragalactic background light $\gamma$-ray attenuation
• Axion-Like Particles and Recent Observations of the Cosmic Infrared Background Radiation
• New Horizons Observations of the Cosmic Optical Background
• A GeV-TeV Measurement of the Extragalactic Background Light
• Probing the 3.6 Micron CIRB with Spitzer in 3 DIRBE Dark Spots
• Measurement of the extragalactic background light spectral energy distribution with VERITAS
• Constraints on the Extragalactic Background Light from Very High Energy Gamma-Ray Observations of Blazars
• The 1 um discontinuity in the Extragalactic Background Light spectrum: an artefact of foreground subtraction
• Bethe-Heitler cascades as a plausible origin of hard spectra in distant TeV blazars
• Constraints to Energy Spectra of Blazars based on Recent EBL Limits from Galaxy Counts
• Estimation of the Extragalactic Background Light using TeV Observations of BL~Lacs
• Search for spectral features in extragalactic background light with gamma-ray telescopes
• EBL Inhomogeneity and Hard-Spectrum Gamma-Ray Sources
• Extragalactic background light models and GeV-TeV observation of blazars
• Constraining Extragalactic Background Light From TeV Blazars
• Probing the evolution of the EBL photon density out to $z\sim 1$ via $\gamma$-ray propagation measurements with Fermi
• Studies of Extragalactic Background Light with TeV BL Lac Objects