Related papers: An 80-kpc Lyman-alpha halo around a high redshift …
Active galactic nuclei (AGNs) in the high-redshift Universe are thought to reside in overdense environments. However, recent works provide controversial results partly due to the use of different techniques and possible suppression of…
We present the results of a survey for Ly$\alpha$ emitters at $z\approx 5.7$ based on optical narrow-band ($\lambda_{\rm c} = 8150$ \AA ~ and $\Delta\lambda = 120$ \AA), and broad-band ($B$, $R_{\rm C}$, $I_{\rm C}$, and $z^\prime$)…
We present the discovery of a candidate of giant radio-quiet Lyman-alpha (Lya) blob (RQLAB) in a large-scale structure around a high-redshift radio galaxy (HzRG) lying in a giant Lya halo, B3 J2330+3927 at redshift z=3.087. We obtained Lya…
The recent discovery of enormous Ly$\alpha$ nebulae (ELANe), characterized by physical extents $>200$ kpc and Ly$\alpha$ luminosities $>10^{44}$ erg s$^{-1}$, provide a unique opportunity to study the intergalactic and circumgalactic medium…
We report the detection of luminous CO(3-2) line emission in the halo of the z=2.6 radio galaxy (HzRG) TXS0828+193, which has no detected counterpart at optical to mid-infrared wavelengths implying a stellar mass < few x10^9 M_sun and…
To obtain an unbiased sample of bright LyA blobs [L(LyA) > 10^43 ergs/s], we have undertaken a blind, wide-field, narrow-band imaging survey in the NOAO Deep Wide Field Survey Bootes field with the Steward Bok-2.3m telescope. After…
We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within 6000 km/s of the QSO's systemic redshift (z_sys). Our sample is based on 731 2.5 <…
We present detailed morphological properties of Lyman alpha emitters (LAEs) at z~ 5.7 in the COSMOS field, based on {\it Hubble Space Telescope} Advanced Camera for Surveys (ACS) data. The ACS imaging in the F814W filter covered 85 LAEs of…
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…
We present the results of VLT/MUSE integral field spectroscopic observations of the Ly$\alpha\,$ emission nebulae associated with 11 high redshift ($z \geq 2.9$) radio galaxies (HzRGs) with DEC $<25^{\circ}$. When considering the other nine…
The baryons inside high-redshift halos with virial temperatures above T=10^4 K cool radiatively as they condense inside dark matter potential wells. We show that the release of the gravitational binding energy, over the halo assembly…
The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2 of sky to m(R)~19, resulted in the discovery of thirty-one quasars with z > 4. High signal-to-noise optical spectrophotometry at 5A resolution has been obtained for the…
This thesis deals with different aspects of a special kind of high redshift galaxy, namely Ly-alpha emitters. Ly-alpha emitters are galaxies found through their Ly-alpha emission, at redshifts larger than z >~ 2 where the emission line has…
Quasars (QSOs) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. However, many observations revealed average or low galaxy densities around $z\gtrsim6$ QSOs. This could be partly…
We examine the possible acceleration mechanisms of the relativistic particles responsible for the extended radio emission in Abell 520. We used new LOFAR 145 MHz, archival GMRT 323 MHz and VLA 1.5 GHz data to study the morphological and…
We present very deep imaging observations, through a narrow-band filter tuned to Lyman alpha at <z = 3.09>, of a volume containing a significant over-density of galaxies at this redshift previously discovered in our survey for…
We have identified an obvious and strong large scale structure at redshift z=5.75 in a wide (31 by 33 arcminute) field, narrowband survey of the Chandra Deep Field South region. This structure is traced by 17 candidate Lyman alpha emitters,…
We have used the Green Bank Telescope to carry out a deep search for redshifted CO J=2-1 line emission from an extended (>17 kpc) Ly-Alpha blob (LAB), "Himiko", at z~6.595. Our non-detection of CO J=2-1 emission places the strong 3-sigma…
We present the first results of a survey designed to understand the origin of the Lyman alpha-forest absorption systems at low redshift. Using the WYFFOS and HYDRA multi-fibre spectrographs on the WHT and WIYN telescopes, we have identified…
The Lyman-$\alpha$ line is expected to be strong in the presence of active star formation and the absence of dust, making it a good tool for finding chemically primitive galaxies in the early universe. We report on a new survey for high…