Name: Zahoor Malik
Affiliation: University of Kashmir
Conference ID : ASI2022_134
Title : Model-independent redshift estimation of BL Lac objects through very-high-energy observations
Authors : Zahoor Malik, Sunder Sahayanathan, Zahir Shah , Naseer Iqbal, Aaqib Manzoor and Nilay Bhatt
Abstract Type: Oral
Abstract Category : Extragalactic Astronomy
Abstract : The very-high-energy (VHE) gamma-ray spectral indices of blazars show a strong correlation with the source redshift. The absence of any such correlation in low-energy gamma-rays and X-rays indicates 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 redshifts of BL Lac objects that were unknown/uncertain earlier. In addition, we compare the observed VHE spectral index–redshift correlation with those predicted from commonly adopted EBL models. Our study highlights the deviation of EBL-model-based predictions from observations, especially at high redshifts.