Modelindependent Reconstruction of UV Luminosity Function and Reionization Epoch
Abstract
We conduct a first comprehensive study of the Luminosity Function (LF) using a nonparametric approach. We use Gaussian Process to fit available luminosity data between redshifts $z \sim 28$. Our freeform LF in the nonparametric approach rules out the conventional Schechter function model to describe the abundancemagnitude relation at redshifts $z=3$ and $4$. Hints of deviation from the Schechter function are also noticed at redshifts 2, 7 and 8 at lower statistical significance. Significant deviation starts for brighter ionizing sources at $M_{\rm UV} \lesssim 21$. The UV luminosity density data at different redshifts are then derived by integrating the LFs obtained from both methods with a truncation magnitude of $17$. In our analysis, we also include the first 90 arcmin$^2$ JWST/NIRCam data at $z \sim 912$. Since at larger magnitudes, we do not find major deviations from the Schechter function, the integrated luminosity density differs marginally between the two methods. Finally, we obtain the history of reionization from a joint analysis of UV luminosity density data along with the ionization fraction data and Planck observation of Cosmic Microwave Background. The history of reionization is not affected by the deviation of LFs from Schechter function at lower magnitudes. We derive reionization optical depth to be $\tau_{\rm re}=0.0494^{+0.0007}_{0.0006}$ and the duration between 10$\%$ and 90$\% $completion of ionization process is found to be $\Delta z\sim 1.627^{+0.059}_{0.071}$.
 Publication:

arXiv eprints
 Pub Date:
 May 2024
 DOI:
 10.48550/arXiv.2405.10180
 arXiv:
 arXiv:2405.10180
 Bibcode:
 2024arXiv240510180A
 Keywords:

 Astrophysics  Astrophysics of Galaxies;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages