UV Background-Induced Bifurcation of the Galactic Morphology

Abstract

Based upon a novel paradigm of the galaxy formation under UV background, the evolutionary bifurcation of pregalactic clouds is confronted with observations on elliptical and spiral galaxies. The theory predicts that the dichotomy between the dissipational and dissipationless galaxy formation stems from the degree of self-shielding from the UV background radiation. This is demonstrated on a bifurcation diagram of collapse epochs versus masses of pregalactic clouds. Using the observed properties, the collapse epochs are assessed for each type of galaxies with attentive mass estimation. By the direct comparison of the theory with the observations, it turns out that the theoretical bifurcation branch successfully discriminates between elliptical and spiral galaxies. This suggests that the UV background radiation could play a profound role for the differentiation of the galactic morphology into the Hubble sequence.

Accepted for publication in MNRAS

References in corpus (6)

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• X-Ray Properties of Early Type Galaxies as Observed with ASCA
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Cited by in corpus (8)

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• Formation of Dwarf Galaxies during the Cosmic Reionization
• Criteria for the Formation of Population III Objects in the Ultraviolet Background Radiation
• On the Possibility of Observing H2 Emission from Primordial Molecular Cloud Kernels
• UV Background-Induced Bifurcation of the Galactic Morphology
• On the Possibility of Observing the Double Emission Line Feature of H${}_2$ and HD from Primordial Molecular Cloud Cores
• Regulated star formation in forming disk galaxies under ultraviolet radiation background
• Formation of globular clusters induced by external ultraviolet radiation