Constraining the formation of NGC 1052-DF2 from its unusual globular cluster population

ABSTRACT The ultra-diffuse galaxy (UDG) NGC 1052-DF2 has a low dark matter content and hosts very unusual globular cluster (GC) population, with median luminosity ?4 times higher than in most galaxies containing about 5 per cent of the galaxy’s stars. We apply theoretical model that predicts initial mass function as galactic environment to investigate origin DF2’s peculiar GC system. Using function, constrains star-forming conditions during formation its GCs, ?9 Gyr ago. predict GCs formed an high gas surface density, $\Sigma _{\rm ISM}\gtrsim 10^3\rm \,{M_\odot}\rm \,{pc}^{-2}$, strong centrifugal support, $\Omega \gtrsim 0.7\rm \,{Myr}^{-1}$, similar nearby circumnuclear starbursts central region Milky Way. extreme required form observed population imply efficiency ?87 cent, contrast strongly current diffuse nature galaxy. Since nuclear starburst would lead rapid in-spiral is ruled out by absence star cluster, we propose plausibly major merger at z ? 1.3. remnant must have undergone significant expansion stellar (and perhaps also matter) component reach present brightness, leading interesting possibility it was caused become UDG. If true, this structural evolution important implications for understanding origins UDGs.