# A Halo Occupation Interpretation Of Quasars At $z\sim1.5$ Using Very Small Scale Clustering Information

## TL;DR

This study combines small and large scale quasar clustering data at z~1.5 to constrain the halo occupation distribution, revealing a low satellite fraction and potential luminosity dependence in quasar hosting halos.

## Contribution

It introduces a combined clustering analysis at multiple scales to refine quasar halo occupation models and explores the impact of dark matter halo concentration on quasar distribution.

## Key findings

- Satellite fraction of quasars is approximately 7%.
- Minimum halo mass hosting quasars is around 2.3 x 10^{12} h^{-1} M_sun.
- Results suggest possible luminosity dependence in quasar halo occupation.

## Abstract

We combine the most precise small scale ($< 100\, \rm h^{-1}kpc$) quasar clustering constraintsto date with recent measurements at large scales ($> 1\, \rm h^{-1}Mpc$) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) to better constrain the satellite fraction of quasars at $z\sim 1.5$ in the halo occupation formalism. We build our Halo Occupation Distribution (HOD) framework based on commonly used analytic forms for the one and two-halo terms with two free parameters: the minimum halo mass that hosts a central quasar and the fraction of satellite quasars that are within one halo. Inspired by recent studies that propose a steeper density profile for the dark matter haloes that host quasars, we explore HOD models at kiloparsec scales and best-fit parameters for models with $10\times$ higher concentration parameter. We find that an HOD model with a satellite fraction of $f_{\rm sat} = 0.071_{-0.004}^{+0.009}$ and minimum mass of $\rm M_{m} = 2.31_{-0.38}^{+0.41} \times 10^{12}\, \, \rm h^{-1} M_{\odot}$ for the host dark matter haloes best describes quasar clustering (on all scales) at $z \sim 1.5$. Our results are marginally inconsistent with earlier work that studied brighter quasars, hinting at a luminosity-dependence to the one-halo term.