A giant central red disk galaxy at redshift $z=0.76$: challenge to theories of galaxy formation

TL;DR

This paper reports the discovery of a massive, red, disk-shaped galaxy at redshift 0.76, which challenges existing galaxy formation theories due to its quiescent, disk-dominated nature at such an early cosmic epoch.

Contribution

It presents the identification and detailed analysis of a giant red central disk galaxy at z=0.76, highlighting its contradiction with current galaxy formation models.

Findings

Galaxy has stellar mass ~10^11.6 M_sun.

Galaxy exhibits a disk morphology with Sersic index n=1.22.

Its existence challenges standard galaxy formation theories.

Abstract

We report a giant red central disk galaxy in the XMM-LSS north region. The region is covered with a rich variety of multiband photometric and spectroscopic observations. Using the photometric data of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) and spectroscopic observation of the Baryon Oscillation Spectroscopic Survey (BOSS), we find that the galaxy has a stellar mass of $\sim 10^{11.6}$ times of the solar mass $M_\odot$. The galaxy has a red color and has an old stellar population, and thus its star formation has stopped. With the photometric image data of Hyper Suprime-Cam (HSC) Subaru Strategic Program, we demonstrate that its luminosity profile is perfectly described by a S\'ersic form with $n=1.22$ indicating disk morphology. We also analyze its environment based on the VIMOS Public Extragalactic Redshift Survey (VIPERS) photometric catalog, and find that its close neighbors are all less massive, indicating that our observed galaxy is sitting at the center of its host halo. Existence of the giant red central disk galaxy seriously challenges the current standard paradigm of galaxy formation, as there is no known physical mechanism to explain the quenching of its star formation. This conclusion is supported by state-of-the-art hydrodynamical simulations of galaxy formation.