Related papers: Limits to Seeing High-Redshift Galaxies Due to Pla…
I assess the problem of morphological and photometric evolution of high-redshift galaxies in the ultraviolet wavelength range. My discussion will partly rely on a new set of template galaxy models, in order to infer the expected changes…
The observed properties of high redshift galaxies depend on the underlying foreground distribution of large scale structure, which distorts their intrinsic properties via gravitational lensing. We focus on the regime where the dominant…
Due to their extreme luminosities, gamma-ray bursts (GRBs) can be detected in hostile regions of galaxies, nearby and at very high redshift, making them important cosmological probes. The investigation of galaxies hosting long-duration GRBs…
Due to the invention of new powerful instruments in the recent past (e.g. 10m class telescopes) high redshift galaxies are no longer a curiosity. High redshift young star forming galaxies can be effectively discriminated from the much more…
If dark matter in the form of compact objects comprises a large fraction of the mass of the universe, then gravitational lensing effects on gamma-ray bursts are expected. We utilize BATSE and Ulysses data to search for lenses of different…
We present the first high redshift (0.3 < z < 1.1) galaxy clusters found by systematically identifying optical low surface brightness fluctuations in the background sky. Using spectra obtained with the Keck telescope and I-band images from…
Although about a dozen high redshift (z larger than 2) starburst galaxies have been recently detected in the CO lines, spectroscopic detections of molecular gas of very young galaxies are still very difficult. The CO lines are usually…
When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and the epoch of reionization? What are the conditions in typical star-forming galaxies at redshifts >~4? Why is galaxy evolution…
The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy from 100 MeV to 100 GeV. The majority of these sources belong to the class of blazars characterized by a quasi-featureless optical spectrum…
In this paper we review the present status and implications of H-alpha surveys at various redshifts. With the advent of sensitive wide-format near-infrared detectors on large telescopes, deep and extensive H-alpha surveys are now feasible…
We present constraints on the stellar-mass distribution of distant galaxies. These stellar-mass estimates derive from fitting population-synthesis models to the galaxies' observed multi-band spectrophotometry. We discuss the complex…
We present Hubble Space Telescope images of 11 high redshift radio galaxies (between $z=2.3$ and $z=3.6$). The galaxies were observed with the WFPC2 camera in a broad band filter (F606W or F707W, roughly equivalent to V or R-band), for 2…
The major cornerstone of future ground-based astronomy is imaging and spectroscopy at the diffraction limit using adaptive optics. To exploit the potential of current AO systems, we have begun a survey around bright stars to study…
We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy…
The success of the Hubble Deep Field (HDF) data in identifying galaxies at redshifts up to ~3 has been quite spectacular. It is possible to extend this to even higher redshifts using infrared techniques, several of which are briefly…
We present the results of the deepest search to date for star-forming galaxies beyond a redshift z~8.5 utilizing a new sequence of near-infrared Wide Field Camera 3 images of the Hubble Ultra Deep Field. This `UDF12' campaign completed in…
The photometric redshift distributions, spectral types, Sersic indices, and sizes of all resolved galaxies in the Hubble Space Telescope Ultra Deep Field (UDF) are studied in order to understand the environment and nature of star formation…
Given its extraordinary spatial resolution and sensitivity, the projected Next Generation Space Telescope (NGST) is likely to detect a large number of high-redshift QSOs lensed by spiral galaxies. Using realistic models for the QSO and…
We have shown previously that galaxy counts from the UV to the near-IR are well-fitted by simple evolutionary models where the space density of galaxies remains constant with look-back time while the star-formation rate rises exponentially.…
Within just the last few years, we have advanced from knowing only a few galaxies at z>2 to having redshifts for nearly 1000 z~2-5 objects. The majority of this sample has been detected through the photometric ``drop-out'' technique used so…