Measuring the Mean Free Path of HI Ionizing Photons with DESI Y1 Quasars

Collaborator: J. Xavier Prochaska (UC Santa Cruz)

We constructed a sample of ~12,600 quasars and perform the mean free path measurements.

Main findings:

• Our measured mean free path is systematically lower than the previous results (Figure 1), especially at \(z\lesssim 4\). We believe that it is mainly due to the neglection of Lyman series opacity evolution of the previous work, which made their results biased toward higher values.
• Incorporating all the measurements from the literaure, we believe the overall evolution of mean free path can be empirically well-described by a broken power law, with the broken redshift \(z_0\sim 5\) (Figure 2), which may have a tight relation with the ending of reionization.
• Our results show the discrepancy with the other empirical IGM absorber models, which indicates the neccessity of improving the current models (Figure 3).

You could read our paper to find a more detailed description of our work! 😉