Galaxy Stellar Mass Functions from z~10 to z~6 using the Deepest Spitzer/IRAC Data: No Significant Evolution in the Stellar-to-Halo Mass Ratio of Galaxies in the First Gyr of Cosmic Time

Understand

We present new stellar mass functions at $z\sim6$, $z\sim7$, $z\sim8$, $z\sim9$ and, for the first time, $z\sim10$, constructed from $\sim800$ Lyman-Break galaxies previously identified over the XDF/UDF, parallels and the five CANDELS fields.

• Our study is distinctive due to (1) the much deeper ($\sim200$ hour) wide-area Spitzer/IRAC imaging at $3.6\mu$m and $4.5\mu$m from the GOODS Re-ionization Era wide Area Treasury from Spitzer (GREATS) program and (2) consideration of $z\sim6-10$ sources over a $3\times$ larger area than previous HST+Spitzer studies.
• The Spitzer/IRAC data enable $\ge2\sigma$ rest-frame optical detections for an unprecedented $50\%$ of galaxies down to a stellar mass limit of $\sim10^{8}\mathcal{M}_\odot$ across all redshifts.
• Schechter fits to our volume densities suggest a combined evolution in characteristic mass $\mathcal{M}^*$ and normalization factor $\phi^*$ between $z\sim6$ and $z\sim8$.