ﻻ يوجد ملخص باللغة العربية
Post-starburst, or E+A galaxies, are the best candidates for galaxies in transition from being gas-rich and star-forming to gas-poor and passively-evolving via galaxy-galaxy mergers. To determine what E+A galaxies become after their young stellar populations fade away, we present the detailed morphologies of 21 E+As using HST images. We find that E+As are similar to early types in that they have large bulge fractions (median B/T = 0.59), high Sersic index (n > 4), and high concentration indices (C > 4.3). The large fraction (70%) of E+As with positive color gradients (i.e., bluer nuclei) indicates that the young stellar populations are more concentrated than the old populations. We show that these positive color gradients can evolve into the negative gradients typical in E/S0s if the central parts of these galaxies are metal enhanced. E+A galaxies stand apart from the E/S0s in the edge-on projection of the Fundamental Plane, implying that E+As have, on average, a M/L that is ~3.8 times smaller than that of E/S0s. The tilt of the E+A FP indicates that the variation among stellar populations in these galaxies is closely tied to their structural parameters such that smaller or less massive galaxies have smaller M/L. We find a population of unresolved compact sources in nine E+As (45%). Their colors and luminosities are consistent with the hypothesis that these are newly formed star clusters. The bright end of the cluster LF is fainter in redder E+As, suggesting that the young star cluster systems have faded or been disrupted as the merger remnant aged. In summary, the morphologies, color profiles, scaling relations, and cluster populations are all consistent with the hypothesis that E+As galaxies are the results of mergers that evolve into early-type galaxies.
One important approach to the study of galaxy evolution is to identify those galaxies whose spectral and/or morphological characteristics suggest that they are in transition. For example, ``E+A galaxies, which have strong Balmer absorption lines and
We present HST/WFPC2 observations of the five bluest E+A galaxies (z~0.1) in the Zabludoff et al. sample to study whether their detailed morphologies are consistent with late-to-early type evolution and to determine what drives that evolution. The mo
We study interstellar dust evolution in various environments by means of chemical evolution models for galaxies of different morphological types. We start from the formalism developed by Dwek (1998) to study dust evolution in the solar neighbourhood
We calculate the transverse momentum dependence in the production of two back-to-back hadrons in electron-positron annihilations at the medium/large energy scales of BES-III and BELLE experiments. We use the parameters of the transverse-momentum-depe
We investigate the evolution of mass-selected early-type field galaxies using a sample of 28 gravitational lenses spanning the redshift range 0 < z < 1. Based on the redshift-dependent intercept of the fundamental plane in the rest frame B band, we m