Year: 2005
Type: article
Abstract: We use hydrodynamical simulations to study the color transformations induced by star formation and active galactic nuclei (AGNs) during major mergers of spiral galaxies. Our modeling accounts for radiative cooling, star formation, and supernova feedback. Moreover, we include a treatment of accretion onto supermassive black holes embedded in the nuclei of the merging galaxies. We assume that a small fraction of the bolometric luminosity of an accreting black hole couples thermally to surrounding gas, providing a feedback mechanism that regulates its growth. The encounter and coalescence of the galaxies triggers nuclear gas inflow, which fuels both a powerful starburst and strong black hole accretion. Comparing simulations with and without black holes, we show that AGN feedback can quench star formation and accretion on a short timescale, particularly in large galaxies where the black holes can drive powerful winds once they become sufficiently massive. The color evolution of the remnant differs markedly between mergers with and without central black holes. Without AGNs, gas-rich mergers lead to elliptical galaxies that remain blue owing to residual star formation, even after more than 7 Gyr have elapsed. In contrast, mergers with black holes produce elliptical galaxies that redden much faster, an effect that is more pronounced in massive remnants where a nearly complete termination of star formation occurs, allowing them to redden to u - r ≃ 2.3 in less than 1 Gyr. AGN feedback may thus be required to explain the population of extremely red massive early-type galaxies, and it appears to be an important driver in generating the observed bimodal color distribution of galaxies in the local universe.
Source: The Astrophysical Journal
DOI: 10.1086/428772
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: Evolution of Structure in the Universe from z=30 to z=3, GALAXY EVOLUTION IN A COSMOLOGICAL CONTEXT, ASTROPHYSICAL AND COSMOLOGICAL PROBES OF SMALL-SCA LE POWER TO TEST COSMOLOGICAL MODELS, The Galaxy / IGM Connection, National Computational Science Alliance, Following the Universe from Dark to Light, PRODUCTION OF NON-THERMAL PARTICLES BY STRUCTURE FORMATION IN THE INTERGALACTIC MEDIUM
OpenAlex ID: W2154955582