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We explore galaxy assembly over the last seven billion years by characterizing normal galaxies along the Hubble sequence, against strongly disturbed merging/interacting galaxies with the widely used CAS system of concentration (C), asymmetry (A), and clumpiness (S) parameters, as well as visual classification. We analyze Hubble Space Telescope (HST) ACS images of ~4000 intermediate and high mass (> 10^9 solar masses) galaxies from the GEMS survey, one of the largest HST surveys conducted to date in two filters. We explore the effectiveness of the CAS criteria [A>S and A>~0.35] in separating normal and strongly disturbed galaxies at different redshifts, and quantify the recovery and contamination rate. We also compare the average star formation rate and the cosmic star formation rate density as a function of redshift between normal and interacting systems identified by CAS.
Bars drive the dynamical evolution of disk galaxies by redistributing mass and angular momentum, and they are ubiquitous in present-day spirals. Early studies of the Hubble Deep Field reported a dramatic decline in the rest-frame optical bar fraction
We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity function at z=4-8. We use deep Hubble Space Telescope imaging over the CANDELS/GOODS fields, the Hubble Ultra Deep Field and the Year 1 Hubble Frontier Field d
A galaxys orientation is one of its most basic observable properties. Astronomers once assumed that galaxies are randomly oriented in space, however it is now clear that some have preferred orientations with respect to their surroundings. Chief among
The variability of the spectral solar irradiance (SSI) over the course of the 11-year solar cycle is one of the manifestations of solar magnetic activity. There is a strong evidence that the SSI variability has an effect on the Earths atmosphere. The
We measure the evolution of the $M_{rm BH}-M_*$ relation using 584 uniformly-selected SDSS quasars at $0.2<z<0.8$. The black-hole masses ($M_{rm BH}$) are derived from the single-epoch virial mass estimator using the H$beta$ emission line, and span t