The Emergence of the Thick Disk in a CDM Universe
نویسندگان
چکیده
The disk galaxy simulated using our chemo-dynamical galaxy formation code, GCD+, is shown to have a thick disk component. This is evidenced by the velocity dispersion versus age relation for solar neighbourhood stars, which clearly shows an abrupt increase in velocity dispersion at lookback time of approximately 8 Gyrs, and is in excellent agreement with observation. These thick disk stars are formed from gas which is accreted to the galaxy during a chaotic period of hierarchical clustering at high redshift. This formation scenario is shown to be consistent with observations of both the Milky Way and extragalactic thick disks. Subject headings: galaxies: formation — galaxies: evolution — Galaxy: thick disk
منابع مشابه
ar X iv : a st ro - p h / 05 03 27 3 v 1 11 M ar 2 00 5 The Emergence of the Thick Disk in a CDM Universe II : Colors and Abundance Patterns
The recently emerging conviction that thick disks are prevalent in disk galaxies, and their seemingly ubiquitous old ages, means that the formation of the thick disk, perhaps more than any other component, holds the key to unravelling the evolution of the Milky Way, and indeed all disk galaxies. In Paper I, we proposed that the thick disk was formed in an epoch of gas rich mergers, at high reds...
متن کاملDisk Galaxies as Cosmological Benchmarks: Cold Dark Matter versus Modified Newtonian Dynamics
We discuss a comparison of models for the formation of disk galaxies both in a Universe dominated by cold dark matter (CDM) and one in which the force law is given by modified Newtonian dynamics (MOND). Our main aim is to address the claim made by McGaugh & de Blok that CDM suffers from severe fine-tuning problems, which are circumvented under MOND. As we show, CDM indeed requires some amount o...
متن کاملتوسعه مدل دیسک دایرهای در نانوکامپوزیتهای پایه پلیمری و تحلیل میکرومکانیک تنشهای پسماند در الیاف تقویت شده با نانولولههای کربنی
In this study, Circular Disk Model (CDM) has been developed to determine the residual stresses in twophase and three- phase unit cell. The two-phase unit cell is consisting of carbon fiber and matrix. The three-phase unit cell is consisting of carbon fiber, carbon nanotubes and matrix in which the carbon fiber is reinforced with the carbon nanotube using electrophoresis method. For different vo...
متن کاملDynamical Effects of CDM Subhalos on a Galactic Disk
We investigate the dynamical interaction between a galactic disk and surrounding numerous dark subhalos as expected for a galaxy-sized halo in the cold dark matter (CDM) models. Our particular interest is to what extent accretion events of subhalos into a disk are allowed in light of the observed thinness of a disk. Several models of subhalos are considered in terms of their internal density di...
متن کاملThe Mucosal Adjuvant Potential of Cross-Linked Dextran Microspheres as Dry Powder
Objective(s) The immunoadjuvant potential of cross-linked dextran microspheres (CDM) as absorption enhancer and Quillaja saponins (QS) as immunomodulator adjuvant was evaluated. Materials and Methods CDM loaded or tetanus-mixed toxoid (TT) or Quillaja saponin (QS) were nasally administered to rabbits in dry powder form, three times in 2 weeks interval and serum IgG and nasal lavage sIgA tite...
متن کامل