Detalles de publicación
PP 012044
Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0’s through major mergers
1-Instituto de Astrofísica de Canarias, C/ Vía Láctea, E-
38200, La Laguna, Canary Islands, Spain
2-Departamento de Astrofísica, Universidad de La Laguna,
Avda. Astrofísico Fco. Sánchez, E-38200, La Laguna,
Canary Islands, Spain
3-Departamento de Astrofísica, Facultad de CC. Físicas,
Universidad Complutense de Madrid, E-28040 Madrid,
Spain
4-Isaac Newton Group of Telescopes, Apartado 321, E-
38700, Santa Cruz de La Palma, Canary Islands, Spain
5-Centro de Estudios de Física del Cosmos de Aragón, E-
44001, Teruel, Spain
6-Instituto de Astrofísica de Andalucía, IAA-CSIC, Apdo.
3044, E-18080 Granada, Spain
7-Max-Planck-Institut für Extraterrestrische Physik,
Giessen-bachstrasse, D-85748, Garching, Germany
8-Universitätssternwarte, Scheinerstrasse 1, D-81679,
München, Germany
9-Department of Astronomy, 477 Bryant Space Center,
University of Florida, Gainesville, FL, USA
10-Associate Astronomer at Steward Observatory, The
University of Arizona, USA
Some recent observations seem to disagree with hierarchical theories of galaxy
formation about the role played by major mergers in the late buildup of massive E-S0’s.
We re-address this question by analysing the morphology, structural distortion level,
and star formation enhancement of a sample of massive galaxies (M∗ > 5 × 1010M⊙)
lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an
initial sample of ~1800 sources with Ks < 20.5 mag over an area ~ 155 arcmin2 on the
Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA
Survey. Red galaxy classes that can be directly associated to intermediate stages of
major mergers and to their final products have been defined. We report observational
evidence of the existence of a dominant evolutionary path among massive red galaxies
at 0.6 < z < 1.5, consisting in the conversion of irregular disks into irregular spheroids,
and of these ones into regular spheroids. This result implies: 1) the massive red regular
galaxies at low redshifts derive from the irregular ones populating the Red Sequence
and its neighbourhood at earlier epochs up to z ~ 1.5; 2) the progenitors of the
bulk of present-day massive red regular galaxies have been disks that seem to have
migrated to the Red Sequence mostly through major mergers at 0.6 < z < 1.2 (these
mergers thus starting at z ~ 1.5); and 3) the formation of E-S0’s that end up with
M∗ > 1011M⊙ at z = 0 through gas-rich major mergers has frozen since z ~ 0.6. All
these facts support that major mergers have played a dominant role in the definitive
buildup of present-day E-S0’s with M∗ > 1011M⊙ at 0.6 < z < 1.2, in good agreement
with hierarchical scenarios of galaxy formation.
formation about the role played by major mergers in the late buildup of massive E-S0’s.
We re-address this question by analysing the morphology, structural distortion level,
and star formation enhancement of a sample of massive galaxies (M∗ > 5 × 1010M⊙)
lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an
initial sample of ~1800 sources with Ks < 20.5 mag over an area ~ 155 arcmin2 on the
Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA
Survey. Red galaxy classes that can be directly associated to intermediate stages of
major mergers and to their final products have been defined. We report observational
evidence of the existence of a dominant evolutionary path among massive red galaxies
at 0.6 < z < 1.5, consisting in the conversion of irregular disks into irregular spheroids,
and of these ones into regular spheroids. This result implies: 1) the massive red regular
galaxies at low redshifts derive from the irregular ones populating the Red Sequence
and its neighbourhood at earlier epochs up to z ~ 1.5; 2) the progenitors of the
bulk of present-day massive red regular galaxies have been disks that seem to have
migrated to the Red Sequence mostly through major mergers at 0.6 < z < 1.2 (these
mergers thus starting at z ~ 1.5); and 3) the formation of E-S0’s that end up with
M∗ > 1011M⊙ at z = 0 through gas-rich major mergers has frozen since z ~ 0.6. All
these facts support that major mergers have played a dominant role in the definitive
buildup of present-day E-S0’s with M∗ > 1011M⊙ at 0.6 < z < 1.2, in good agreement
with hierarchical scenarios of galaxy formation.