The Fundamental Plane of Bulges at Intermediate Redshift

TL;DR

This study investigates the properties and evolution of galactic bulges at intermediate redshifts, comparing their Fundamental Plane relations to those of spheroidal galaxies, revealing similar evolutionary patterns.

Contribution

It provides a detailed analysis of bulge parameters and stellar velocity dispersions at intermediate redshift, highlighting their evolutionary similarities to spheroidal galaxies.

Findings

Bulges with B/T > 0.2 show similar evolution to low luminosity spheroidals.

Bulges' mass assembly histories are comparable to those of spheroidal galaxies.

The Fundamental Plane relation holds for distant bulges, indicating similar structural evolution.

Abstract

We report on a new study aimed at understanding the diversity and evolutionary properties of distant galactic bulges in the context of well-established trends for pure spheroidal galaxies. Bulges have been isolated for a sample of 137 spiral galaxies in the GOODS fields within the redshift range 0.1 < z < 1.2. Using proven photometric techniques we determine for each galaxy the characteristic parameters (size, surface brightness, profile shape) in the 4 GOODS-ACS imaging bands of both the disk and bulge components. Using the DEIMOS spectrograph on Keck, precision stellar velocity dispersions were secured for a sizeable fraction of the bulges. This has enabled us to compare the Fundamental Plane of our distant bulges with that of field spheroidal galaxies in a similar redshift range. Bulges in spiral galaxies with a bulge-to-total luminosity ratio (B/T) > 0.2 show very similar patterns of evolution to those seen for low luminosity spheroidals. To first order, their recent mass assembly histories are equivalent.