Photometric properties of classical bulge and pseudo-bulge galaxies at 0.5 ≤ z < 1.0

¹ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
² School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
³ Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
⁴ Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, China

^⋆ Corresponding author; hujia@nao.cas.cn; hujia@nao.cas.cn

Received: 31 July 2024
Accepted: 26 September 2024

Abstract

Context. We compare the photometric properties and specific star formation rate (sSFR) of classical- and pseudo-bulge galaxies with M_∗ ≥ 10^9.5 M_⊙ at 0.5 ≤ z < 1.0, selected from all five CANDELS fields. We also compare these properties of bulge galaxies at lower redshift selected from MaNGA survey in previous work.

Aims. This paper aims to study the properties of galaxies with classical and pseudo-bulges at intermediate redshift, to compare the differences between different bulge types, and to understand the evolution of bulges with redshift.

Methods. Galaxies are classified into classical bulge and pseudo-bulge samples according to the Sérsic index n of the bulge component based on results of two-component decomposition of galaxies, as well as the position of bulges on the Kormendy diagram. For the 105 classical bulge and 86 pseudo-bulge galaxies selected, we compare their size, luminosity, and sSFR of various components.

Results. At a given stellar mass, most classical bulge galaxies have smaller effective radii, larger B/T, brighter and relatively larger bulges, and less active star formation than pseudo-bulge galaxies. In addition, the two types of galaxies have larger differences in sSFR at large radii than at the central region at both low- and mid-redshifts.

Conclusions. The differences between the properties of the two types of bulge galaxies are generally smaller at mid-redshift than at low-redshift, indicating that they are evolving to more distinct populations towards the local universe. Bulge type is correlated with the properties of their outer disks, and the correlation is already present at redshifts as high as 0.5 < z < 1.