Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-12-13
2006, MNRAS, 368, 2.
Astronomy and Astrophysics
Astrophysics
MNRAS in press, 21 pages, 11 figures
Scientific paper
10.1111/j.1365-2966.2006.10145.x
We address the origin of the robust bi-modality observed in galaxy properties about a characteristic stellar mass ~3x10^{10}Msun. Less massive galaxies tend to be ungrouped blue star-forming discs, while more massive galaxies are typically grouped red old-star spheroids. Colour-magnitude data show a gap between the red and blue sequences, extremely red luminous galaxies already at z~1, a truncation of today's blue sequence above L_*, and massive starbursts at z~2-4. We propose that these features are driven by the thermal properties of the inflowing gas and their interplay with the clustering and feedback processes, all functions of the dark-matter halo mass and associated with a similar characteristic scale. In haloes below a critical shock-heating mass M_shock~10^{12}Msun, discs are built by cold streams, not heated by a virial shock, yielding efficient early star formation. It is regulated by supernova feedback into a long sequence of bursts in blue galaxies constrained to a "fundamental line". Cold streams penetrating through hot media in M>M_shock haloes preferentially at z>2 lead to massive starbursts in L>L_* galaxies. At z<2, in M>M_shock haloes hosting groups, the gas is heated by a virial shock, and being dilute it becomes vulnerable to feedback from energetic sources such as AGNs. This shuts off gas supply and prevents further star formation, leading by passive evolution to "red-and-dead" massive spheroids starting at z~1. A minimum in feedback efficiency near M_shock explains the observed minimum in M/L and the qualitative features of the star-formation history. The cold flows provide a hint for solving the angular-momentum problem. When these processes are incorporated in simulations they recover the main bi-modality features and solve other open puzzles.
Birnboim Yuval
Dekel Avishai
No associations
LandOfFree
Galaxy Bimodality due to Cold Flows and Shock Heating does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Galaxy Bimodality due to Cold Flows and Shock Heating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Galaxy Bimodality due to Cold Flows and Shock Heating will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-115016