Finding the Most Massive Distant Galaxies by Using the Hyper Surprime-Cam Data

Chien Lin^1*, Chorng-Yuan Hwang¹

¹Institute of Astronomy, National Central University, Taoyuan, Taiwan

* Presenter:Chien Lin, email:m1069011@gm.astro.ncu.edu.tw

The formation of distant massive galaxies is still unclear. Since massive galaxies show up in the later epoch of galaxy evolution due to long-time accretion of mass, huge massive galaxies at high redshifts, which refer to the early universe, seem to be unusual. In previous works, we found that several merger candidates might be extremely massive mergers with mass up to 10 13 solar mass, which is as massive as the most massive galaxies at the local universe. What causes the galaxies to become such massive in early time is an interesting issue. Furthermore, our early results suggested that these galaxies are gas-poor dry mergers, which suggest that the parent galaxies should have undergone significant evolution in an even earlier stage. To find more massive galaxies and investigate the properties of the galaxies, we used the Hyper Surprime-Cam (HSC) grizy data observed with the Subaru Telescope. Using these multi-band photometric results to further constrain the redshifts and mass of our candidates, we've found 522 galaxies with stellar mass greater than 10 13 solar mass, and 40 of them have SDSS spec-z data. Although some of these spectral data shows the objects are QSOs, we tried to subtract the effect of QSOs from the galaxies and found that the rest of the galaxies still carry large stellar masses.

Keywords: massive galaxies, distant galaxies, Hyper Suprime-Cam (HSC)