Combining high-z galaxy luminosity functions with Bayesian evidence

Abstract

Galaxy formation during the first billion years of our Universe remains a challenging problem at the forefront of astrophysical cosmology. Although these $z\ge 6$ galaxies are likely responsible for the last major phase change of our Universe, the epoch of reionization (EoR), detailed studies are possible only for relatively rare, bright objects. Characterizing the fainter galaxies which are more representative of the population as a whole is currently done mainly through their non-ionizing UV luminosity function (LF). Observing the faint end of the UV LFs is nevertheless challenging, and current estimates can differ by orders of magnitude. Here we propose a methodology to combine disparate high-$z$ UV LF data sets in a Bayesian framework: Bayesian Data Averaging (BDA). Using a flexible, physically-motivated galaxy model, we compute the relative evidence of various $z=6$ UV LFs within the magnitude range $-20\le M_{\mathrm{UV}}\le -15$ which is common to the data sets. Our model, based primarily on power-law scalings of the halo mass function, naturally penalizes systematically jagged data points as well as mis-estimated errors. We then use the relative evidence to weigh the posteriors obtained from disparate LF observations during the EoR, $6\le z\le 10$. The resulting LFs suggest that the star formation rate density (SFRD) integrated down to a UV magnitude of -17 represent $60.9_{-9.6}^{+11.3}\%$ / $28.2_{-10.1}^{+9.3}\%$ / $5.7_{-4.7}^{+4.5}\%$ of the total SFRD at redshifts 6 / 10 / 15. The BDA framework we introduce enables galaxy models to leverage multiple, analogous observational data sets.

References in corpus (12)

• Bayes in the sky: Bayesian inference and model selection in cosmology
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• An absorption profile centred at 78 megahertz in the sky-averaged spectrum
• Massloss of galaxies due to a UV-background
• Protostar Formation in the Early Universe
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionisation
• Essential physics of early galaxy formation
• Dust attenuation, dust emission, and dust temperature in galaxies at z>=5: a view from the FIRE-2 simulations
• The Two-Piece Normal, Binormal, or Double Gaussian Distribution: Its Origin and Rediscoveries
• The Physics and Early History of the Intergalactic Medium
• The Minimum Halo Mass for Star Formation at z = 6 - 8

Cited by in corpus (10)

• HERA Phase I Limits on the Cosmic 21-cm Signal: Constraints on Astrophysics and Cosmology During the Epoch of Reionization
• The Evolution of the Lyman-Alpha Luminosity Function During Reionization
• GALLUMI: A Galaxy Luminosity Function Pipeline for Cosmology and Astrophysics
• Constraints on warm dark matter from UV luminosity functions of high-z galaxies with Bayesian model comparison
• Properties of reionization-era galaxies from JWST luminosity functions and 21-cm interferometry
• First Constraints on Small-Scale Non-Gaussianity from UV Galaxy Luminosity Functions
• ETHOS -- An Effective Theory of Structure Formation: Impact of Dark Acoustic Oscillations on Cosmic Dawn
• Constraints on Primordial Power Spectrum from Galaxy Luminosity Functions
• Probing Compensated Isocurvature with the 21-cm Signal during Cosmic Dawn
• The 21-cm signal from the Cosmic Dawn: metallicity dependence of high mass X-ray binaries