相关论文: HST Observations of BL Lacertae Environments

Optical, near-infrared, and radio observations of the BL Lac object PKS2155-304 were obtained simultaneously with a continuous UV/EUV/X-ray monitoring campaign in 1994 May. Further optical observations were gathered throughout most of 1994.…

We report the discovery of four galaxy candidates observed 450 - 600 Myr after the Big Bang with photometric redshifts between z ~ 8.3 - 10.2 measured using the JWST NIRCam imaging of the galaxy cluster WHL0137-08 observed in 8 filters…

AIMS. We are studying an unbiased sample of 42 nearby (z < 0.2) BL Lacertae objects with a multi-wavelength approach. The results of VLBI observations were presented in the first paper of this series. In this paper, we study the…

At large redshifts, a cluster or group may be too distant for the galaxies within the cluster to be detected individually. However, the light from these ``undetected'' galaxies still modulates the surface brightness of the background sky.…

We have calculated variability Doppler boosting factors, Lorentz factors, and viewing angles for a large sample of sources by using total flux density observations at 22 and 37 GHz and VLBI data. We decomposed the flux curves into…

Hubble Space Telescope images of high-redshift galaxies selected via color and photometric redshifts are used to examine the size and axial-ratio distribution of galaxies as a function of redshift at lookback times t > 8 Gyr. These…

We present the results of a photometric redshift analysis designed to identify z>6 galaxies from the near-IR HST imaging in three deep fields (HUDF, HUDF09-2 & ERS). By adopting a rigorous set of criteria for rejecting low-z interlopers,…

We present initial results of a program to obtain and analyze HST WFPC2 images of galaxies identified in an imaging and spectroscopic survey of faint galaxies in fields of HST spectroscopic target QSOs. We measure properties of 87 galaxies,…

Direct redshift determination of BL Lac objects is highly challenging as the emission in the optical and near-infrared (NIR) bands is largely dominated by the non-thermal emission from the relativistic jet that points very close to our line…

We report on deep near-infrared observations obtained with the Wide Field Camera 3 (WFC3) onboard the Hubble Space Telescope (HST) of the first five confirmed gravitational lensing events discovered by the Herschel Astrophysical Terahertz…

We present the radio detection of 18 BL Lac objects from our survey of over 575 square degrees of sky. These 18 objects are located within 20 arcsec of the X-ray position, of which 11 have a measured red-shift. All candidates are radio…

The BL-Lac family of active galaxies possess almost featureless spectra and exhibit rapid variability over their entire spectral range. A number of models have been developed to explain these extreme properties, several of which have…

Hubble Space Telescope WFPC2 images of the Local Group dwarf galaxy Tucana reveal an unbiased sample of distant field galaxies. While a large number of these galaxies can be classified according to standard Hubble types, a significant…

We have carried out HST snapshot observations at 1.1 $\mu$m of 281 candidate strongly lensed galaxies identified in the wide-area extragalactic surveys conducted with the Herschel space observatory. Our candidates comprise systems with flux…

We present the results of a new search for galaxies at redshift z ~ 9 in the first two Hubble Frontier Fields with completed HST WFC3/IR and ACS imaging. To ensure robust photometric redshift solutions, and to minimize incompleteness, we…

Galaxy clusters magnify background objects through strong gravitational lensing. Typical magnifications for lensed galaxies are factors of a few but can also be as high as tens or hundreds, stretching galaxies into giant arcs. Individual…

We present results from a 221.9 ks Chandra exposure of the HDF-N and its vicinity, concentrating on the 8.6' X 8.7' area covered by the Caltech Faint Field Galaxy Redshift Survey (the `Caltech area'). The minimum detectable fluxes in the…

We present an early analysis on the search for high redshift galaxies using the deepest public JWST imaging to date, the NGDEEP field. This data consists of 6-band NIRCam imaging on the Hubble Ultra Deep Field-Par2, covering a total area of…

The gravitational potential responsible for the lensing effect in SBS 1520+530 is studied over length scales from a few arc-seconds to a few arc-minutes. For this purpose, we use sharply deconvolved Hubble Space Telescope images in the…

A clear insight of the galaxies hosting active galactic nuclei is of fundamental importance for understanding the processes of galaxies and nuclei formation and their cosmic evolution. A good characterization of the host galaxies properties…