Related papers: Optical spectroscopy of high redshift BL Lac objec…

Quasars with a high redshift (z) are important to understand the evolution processes of galaxies in the early universe. However only a few of these distant objects are known to this date. The costs of building and operating a 10-metre class…

Using the newly available infrared images of the Hubble Deep Field in the J, H, and K bands and an optimal photometric method, we have refined a technique to estimate the redshifts of 1067 galaxies. A detailed comparison of our results with…

Using the multislit LDSS-2 spectrograph on the {\it William Herschel Telescope} we have completed a redshift survey in the magnitude range $22.5<B< 24$ which has produced 73 redshifts representing a 73\% complete sample uniformly-selected…

We present deep radio maps from the Very Large Array (VLA) for 16 sources detected in a sub-millimeter (submm) survey of the distant Universe. Our deep VLA 1.4-GHz maps allow us to identify radio counterparts or place stringent limits…

Low-resolution spectrographs used to have difficulties to determine redshifts of galaxies at $z\approx1$ and $z\approx3$. Spectral emission and absorption lines of magnesium and iron redshifted to $z\approx1$ fall close to hydrogen,…

The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS following the discovery by Fermi-LAT. The lack of both emission and absorption lines in BL-Lacs make the estimation of their redshifts very difficult.…

Around $10^5$ strongly lensed galaxies are expected to be discovered with Euclid and the LSST. Utilising these large samples to study the inner structure of lens galaxies requires source redshifts, to turn lens models into mass…

In this paper: 1. The assumption of the dependence of Doppler factor on the emission frequency (Fan et al. 1993) is used to explain the observational differences between the radio-selected BL Lac objects(RBLs) and the X-Ray-Selected BL Lac…

The most remarkable class of high-redshift objects observed so far is extended Ly$\alpha$ emission-line blobs found in an over-density region at redshift 3.1. They may be either a dust-enshrouded, extreme starburst galaxy with a large-scale…

We describe a new method for measuring the true redshift distribution of any set of objects studied only photometrically. The angular cross-correlation between objects in a photometric sample with objects in some spectroscopic sample as a…

Using deep Keck spectroscopy of Lyman break galaxies selected from infrared imaging data taken with WFC3/IR onboard the Hubble Space Telescope, we present new evidence for a reversal in the redshift-dependent fraction of star forming…

The escape fraction of LyC ionizing radiation ($f_{lyc}$) is crucial for understanding reionization, yet difficult to measure at $z \gtrsim 4$. Recently, studies have focused on calibrating indirect indicators of $f_{lyc}$ at $z \sim 0.3$,…

We present preliminary results from the first 3 months of the Swift BAT high galactic latitude survey in the 14--195 keV band. The survey reaches a flux of \~10^{-11} erg/cm^2/s and has ~2.7' (90% confidence) positional uncertainties for…

Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good…

We calculate the gamma-ray spectrum of a distant blazar, PKS 1424+240, located at redshift z > 0.6035, where the optical depth to primary gamma rays of the highest observed energies is \tau > 5. The spectral shape agrees well with what is…

We present the results of a study of a large sample of luminous (z'{AB}<26) Lyman break galaxies (LBGs) in the redshift interval 4.7<z<6.3, selected from a contiguous 0.63 square degree area covered by the UKIDSS Ultra Deep Survey (UDS) and…

The identification of galaxies at extreme distances provides our most direct information on the earliest phases of galaxy formation. The distance implied by redshifts z > 5 makes this a challenging endeavor for even the most luminous…

Some studies suggest that the dust temperatures ($T_\mathrm{d}$) in high-redshift ($z\gtrsim 5$) Lyman break galaxies (LBGs) are high. However, possible observational bias in $T_\mathrm{d}$ is yet to be understood. Thus, we perform a simple…

We present spectroscopic observations of six optical counterparts of intermediate luminosity X-ray sources (ULXs) around nearby galaxies. The spectra of the six objects show the presence of broad emission features. The identification of…

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has recently surveyed ~8.7 deg^2 centered on GOODS-South at 250, 350, and 500 microns. In Dye et al. (2009) we presented the catalogue of sources detected at 5-sigma in at…