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arXiv · 2110.15953

Model-independent Redshift Estimation of BL Lac Objects through VHE Observations

Malik Zahoor·Sunder Sahayanathan·Shah Zahir·Naseer Iqbal·Aaqib Manzoor·Nilay Bhatt
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Abstract

The very high energy (VHE) gamma-ray spectral indices of blazars show strong correlation with the source redshift. Absence of any such correlation in low energy gamma rays and X-rays indicate the presence of Extragalactic Background Light (EBL) induced absorption of VHE gamma rays. By employing a linear regression analysis, this observational feature of blazars is used to constrain the redshift of BL Lac objects which was unknown/uncertain earlier. Additionally, we also compare the observed VHE spectral index-redshift correlation with the ones predicted from commonly adopted EBL models. Our study highlights the deviation of the EBL model based predictions from the observation especially at high redshifts.

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Malik Zahoor, Sunder Sahayanathan, Shah Zahir, Naseer Iqbal, Aaqib Manzoor, Nilay Bhatt. 2021-10-29. Model-independent Redshift Estimation of BL Lac Objects through VHE Observations. https://doi.org/10.1093/mnras%2Fstab3173

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