The galaxy-IGM part of the Lyman-break survey currently consists of measured redshifts for more than 1000 galaxies with redshift $1.5\lesssim z\lesssim 3.5$ along the sight-lines to 25 background QSOs. One of the goals of the survey was to measure the influence on the intergalactic medium of energetic feedback from star and black-hole formation. This talk begins with a description of the observed correlations between galaxies and intergalactic absorption lines and ends with a discussion of whether any of the observations provide clear evidence for Mpc-scale superwinds. Although our own observations remain fairly ambiguous, other observations strongly disfavour a very high redshift ($z\sim 10$) for the creation of intergalactic metals.

Thanks to the Sloan Digital Sky Survey, we now know that the Universe becomes opaque to Ly$\alpha$ photons at $z \sim 6$. This presents an obvious challenge for attempts to study the Universe at high redshifts with quasar absorption lines. I discuss two ways to extract more information about reionisation than the simple presence of complete Gunn-Peterson absorption. First, we still expect to see metal line absorption red-ward of Ly$\alpha$. This will allow us to probe the early phases of metal enrichment in the intergalactic medium; the lines can be quite strong because the enriched regions are relatively compact. This is particularly important because metals are a crucial feedback mechanism in the early Universe. Second, we expect to see isolated Ly$\alpha$ transmission features even before the final stages of reionisation. These features allow us to learn about the topology of reionisation and the condensation of the cosmic web at $z \sim 6$.

We present new Keck/HIRES observations of seven of the highest-redshift known quasars. These include four with $z_{\rm qso}\ge 5.8$ and two with $z_{\rm qso}\ge 6.3$. The data will be used to produced a complete statistical description of the Ly$\alpha$ forest at $z > 5$, allowing us to better assess the significance of the strong absorption seen at $z>6.2$. We introduce the statistics of transmission gaps as a means of characterising the high-redshift evolution of the forest. In addition, we identify several clear absorption lines of low optical depth in the quasar proximity regions and briefly discuss using these to place constraints on the thermal history of the IGM at $z>5$.

The recent development of large, complete samples which identify high-redshift galaxies at $z\sim5.7$ and $z\sim 6.5$ from deep, wide-field surveys provides detailed information on the earliest galaxies, their numbers, spatial and kinematic distributions, and implications for early reionisation of the IGM. In this contribution we present results of spectroscopic studies of $z\sim 5.7$ and $z\sim6.5$ galaxies identified from our deep, Lyman alpha narrow-band and multicolour surveys conducted with the SuprimeCam mosaic CCD camera on the 8.3-m Subaru telescope and observed with the DEIMOS multi-object spectrograph on Keck. The luminosity function of the $z\sim6.5$ galaxies is shown to be similar to the luminosity function of the $z\sim 5.7$ galaxy samples, suggesting that a substantial star-forming population is already in place at $z\sim 6.5$. Comparisons of both individual and stacked spectra of galaxies in these two samples show that the Lyman alpha emission profiles, equivalent widths, and continuum break strengths do not substantially change over this redshift interval. The wide-field nature of the surveys also permits mapping of the large-scale distribution of high-redshift galaxies in spatial structures extending across individual SuprimeCam fields ($\sim 60$ Mpc). Field-to-field variations in the number of objects at $z\sim 6.5$ may shortly be able to place constraints on the porosity of the reionisation boundary.

The propagation of cosmological ionisation fronts (I-fronts) during reionisation is strongly influenced by small-scale structure. Here we summarise our recent attempts to understand the effect of this small-scale structure. We present high resolution cosmological N-body simulations at high-z ($z>6$) which resolve a wide range of halo mass, from mini-halos to clusters of large, rare halos. We also study how mini-halos affect I-fronts, through simulations of mini-halo photo-evaporation including numerical gas dynamics with radiative transfer. Furthermore, we modify the I-front propagation equations to account for evolving small-scale structure, and incorporate these results into a semi-analytical reionisation model. When intergalactic medium clumping and mini-halo clustering around sources are included, small-scale structure affects reionisation by slowing it down and extending it in time. This helps to explain the observations of the Wilkinson Microwave Anisotropy Probe, which imply an early and extended reionisation epoch. We also study how source clustering affects the evolution and size of H II regions, finding, in agreement with simulations, that H II regions usually expand, and rarely shrink. Hence, “relic H II regions” are an exception, rather than the rule. When the suppression of small-mass sources in already-ionised regions by Jeans-mass filtering is accounted for, H II regions are smaller, delaying overlap. We also present a new numerical method for radiative transfer which is fast, efficient and easily coupled to hydrodynamics and N-body codes, along with sample tests and applications.

Absorbers seen in the spectrum of background quasars are a unique tool to select HI-rich galaxies at all redshifts. These allow us to determine the cosmological evolution of H I gas, $\Omega_{\rm HI+HeII}$, a possible indicator of gas consumption as star formation proceeds. The damped Lyman-$\alpha$ systems (DLAs with NHI$\ge$ 10$^{20.3}$ cm$^{-2}$) in particular are believed to contain a large fraction of the H I gas, but there are also indications that lower column density systems, namely “sub-damped Lyman-$\alpha$” systems play a role at high-redshift. Here we present the discovery of high-redshift sub-DLAs based on 17 $z>4$ quasar spectra observed with the Ultraviolet-Visual Echelle Spectrograph (UVES) on VLT. This sample is composed of 21 new sub-DLAs which, together with another 10 systems from previous ESO archive studies, make up a homogeneous sample. The redshift evolution of the number density of several classes of absorbers is derived and shows that all systems seem to be evolving in the redshift range from $z=5$ to $z\sim3$. The redshift evolution of the column density distribution, $f(N,z)$, down to NHI=10$^{19}$ cm$^{-2}$ is also presented. A departure from a power law due to a flattening of $f(N,z)$ in the sub-DLA regime is present in the data. $f(N,z)$ is further used to determine the H I gas mass contained in sub-DLAs at $z>2$. The complete sample shows that sub-DLAs are important at all redshifts from $z=5$ to $z=2$.

LOFAR, the Low Frequency Array, is a new low frequency telescope that is currently being built in the Netherlands. It will initially observe at frequencies from 30 to 240 MHz with baselines of up to 100 km. The aim for the second phase is to carry out sensitive observations below 30 MHz and to extend the maximum baselines up to 400 km. The design of LOFAR is driven by four fundamental astrophysical applications: (i) the epoch of reionisation; (ii) extragalactic surveys and their exploitation to study the formation and evolution of clusters, galaxies, and black holes; (iii) transient sources and their association with high energy objects such as gamma ray bursts; and (iv) cosmic ray showers and their exploitation to study the origin of ultra-high energy cosmic rays. Particularly relevant for this conference is LOFAR's ability to study the epoch of reionisation through observations of the redshifted 21 cm line. This will address several important issues including the source of reionisation and the reionisation history of the Universe. In addition to the science case, LOFAR's instrumental concepts and time line are briefly reviewed. The main technical challenges for LOFAR include rejection of man-made radio interference, dealing with the corrupting influence of the ionosphere on the observations, and minimising contaminations of the EOR signal by foreground discrete astrophysical sources.

By investigating properties from the infrared (IR) to the optical of IR-selected QSOs (IR QSOs), optically selected QSOs (PG QSOs), and narrow-line Seyfert 1 galaxies (NLS1s) in the local Universe, we find that the IR excess in IR QSOs is mostly in the far-IR, and their IR spectral indices suggest that the excess emission is caused by starbursts rather than AGNs. The ratio of the star formation rate and the accretion rate is about several hundred for IR QSOs, but decreases with the central black hole mass. We also study an optically selected QSO sample at high redshift with hyper-luminous far-IR luminosities. We find that similar to IR QSOs at low redshift, these high redshift QSOs have a far-IR excess also, which should be due to the contribution of starbursts heating the dust. But the ratio of star formation rate to accretion rate for QSOs at high redshift is typically smaller than that for IR QSOs at low redshift, which hints at the relatively faster growth of black holes at early epochs.

The intergalactic medium revealed by the numerous absorption lines seen in quasar spectra (the so-called Ly $\alpha$ forest) is believed to trace the potential wells of the dark matter. This is a unique tool to derive the power-spectrum of the initial fluctuations from high resolution and high S/N ratio spectra. One of the major limitations in these studies is the accuracy to which the quasar continuum is known. To investigate this problem, we have observed at intermediate spectral resolution ten bright and high redshift quasars (2.1 $< z_{em} <$ 4.7) that have also been observed with UVES. We shall compare the continuum determinations for both data sets.

In recent years there has been rapid progress in the research of Active Galactic Nuclei (AGNs), such as central super-massive black holes (SBH), accretion processes, and their host galaxies. Using data from ROSAT point sources, we found that the soft X-ray spectra of narrow-line Seyfert 1 galaxies (NLS1s) and Blazars become harder during X-ray flux increases, while the spectra of broad-line AGNs (BL AGNs) become softer. From ASCA data, we found that NLS1s and BL AGNs follow the same $\sigma^{2}-M_{MBH}$ relation, where $\sigma^{2}$ is the excess variance in the hard X-ray band. With the accretion efficiency of AGNs, we found that most of the radio-loud quasars possibly possess a Kerr SBH, while the Seyfert 1 galaxies and radio-quiet quasars possess Schwarzschild SBH. We also studied the relation between the central black holes and their host galaxies. It was found that NLS1s appear to have genuinely lower MBH/bulge mass ratios. And the width of the [O III] line is not a good tracer of host velocity dispersion. NLS1s play a special role in our understanding of the evolution of galaxies and their central SBHs.

We study the cross-correlation between 716 Mg II quasar absorption systems and $\sim 100,000$ Luminous Red Galaxies (LRGs) selected from the Sloan Digital Sky Survey Data Release 3 in the redshift range $0.4\!\leq\!z\!\leq\!0.8$. The Mg II systems were selected to have $\lambda\lambda$ 2796 & 2803 rest-frame equivalent widths $\geq\!1.0$$\AA\$ and identifications confirmed by the FeII$\lambda 2600$ or MgI$\lambda 2852$ lines. Over co-moving scales 0.2–13$h^{-1}{\rm \,Mpc}$, the MgII–LRG cross-correlation has an amplitude $0.69 \pm 0.09$ times that of the LRG–LRG auto-correlation. Since LRGs have halo-masses of $10^{13}$ M$_{\odot}$, this strong cross-correlation signal implies that the absorber host-galaxies have halo-masses $1-2\times 10^{12}$ M$_{\odot}$.

The spatial distribution of the gas in the intergalactic medium and its physical properties can be recovered thanks to the characteristics of the Ly$\alpha$ absorption lines that are observed in the spectra of high redshift quasars, the so-called Ly$\alpha$ forest. We use inversion methods applied to a network of lines of sight to infer the topology of the intergalactic medium, based on reconstruction of the density field. The method has already been tested on simulated data.

Search for the time variation of the fundamental constants is motivated by various unification theories. Here we present constraints on the variation of the fine-structure constant $\alpha$($\equiv {e^2/\hbar c}$) obtained using UVES/VLT samples of QSO absorption systems. We find ${<\Delta\alpha/\alpha}>_{w}={(-0.06\pm0.06)\times10^{-5}}$ using 23 Mg II systems and the many-multiplet (MM) method. Well selected 15 Si IV systems provide ${<\Delta\alpha/\alpha}>_{w}={(0.15\pm0.43)\times10^{-5}}$. Absence of detectable variation in $\alpha$ is also confirmed by our new very high resolution ($R\sim 100,000$) observation of $z_{\rm abs}=1.1508$ toward HE 0515–4414 using HARPS on the ESO 3.6m telescope.

We investigate the 3-D matter distribution at $z\sim 2$ with high resolution ($R\sim 40,000$) spectra of QSO pairs and groups obtained with the UVES spectrograph at ESO VLT. Our sample is unique for the number density of objects and the variety of separations, between $\sim 0.5$ and 7 proper Mpc. We compute the real space cross-correlation function of the Lyman-$\alpha$ forest transmitted fluxes. There is a significant clustering signal up to $\sim 2$ proper Mpc, which is still present when absorption lines with high column density ($\log N \ge 13.8$) are excluded.

We attempt to define the structural properties of Broad Absorption Line (BAL) QSOs and their relationship with the general quasar population using the Eigenvector 1 correlations. We identify 8 low-redshift quasars (z $<$ 0.5, 6 with a BALnicity index $>$ 0 km s$^{-1}$) where it was possible to combine optical and UV spectroscopic observations. The special utility of low-$z$ quasars involves our ability to discuss CIV$\lambda$1549 BAL QSOs in the context of the Eigenvector 1 optical parameter space and to have a reliable measure of the quasar rest frame. We find that the majority of the BAL sources are population A sources as defined in Sulentic et al. (2000). At least 2 sources that are hosted by ultra-luminous IR galaxies show intriguing effects in their nuclear spectra. A possible correlation between the terminal velocity and luminosity L also suggests that the luminosity to black hole mass ratio ($L/M$) is a governing factor with the largest terminal velocity BALs showing the highest $L/M$ values. The CIV$\lambda$1549 emission line profiles of classical BALs show the ubiquitous E1 population A blue-shift that supports a disk+wind scenario with an opening angle of $<$ 45$^\circ$. Observation of “secondary” BAL features roughly in correspondence with the mean radial velocity of the CIV$\lambda$1549 emission motivates us to model the BAL systems with an additional component that may share the BLR outflow and may be co-axial with the accretion disk, perhaps associated to a significant black hole spin.

In this paper, we present a statistical study of the X-ray properties of 11 isolated early-type galaxies (IEGs) observed with the Chandra ACIS-S3, and then discuss the implications of these properties.

We present a model which allows for a self-consistent calculation of spectrophotometric, chemical, and dust evolution of spiral and irregular galaxies. Dust evolution is treated without the Instantaneous Recycling Approximation on the basis of the Dwek (1998) model, where up-to-date dust yields for SNe and intermediate mass stars on their AGB phase are taken into account. Confronting model results with the chemical abundances observed in DLA systems, we conclude that spiral and irregular galaxies are good candidates for DLAs.

We present new FUSE and HST/STIS observations of two high Galactic latitude AGN that we use to measure the nuclear wind velocity of the Milky Way for the first time. We find high velocity C III & O VI at a heliocentric velocity of $+163 \pm 8 {\rm km s^{-1}}$ and C III & N V at $-105 \pm 14 {\rm km s^{-1}}$ toward PKS 2005–489 ($l=350^{\circ}, b=-33^{\circ}$) and C III, C IV, & Si IV and C III & O VI toward Mrk 1383 ($l=349^{\circ}, b=55^{\circ}$) at $+48 \pm 4 {\rm km s^{-1}}$ and $+94 \pm 7 {\rm km s^{-1}}$, respectively. We have estimated the Galactocentric escape velocity of gas above the Galactic Centre along the PKS 2005–489 and Mrk 1383 sight-lines to be $\geq\,$$215 \pm 35$ and $\geq\,$$145 \pm 25 {\rm km s^{-1}}$, respectively. Thus, we have detected both infalling and bound outflowing gas from the Galactic Centre, indicating that the Milky Way does not produce a starburst wind, but a bound Galactic “fountain” instead.

We find evidence for dust in the intervening QSO absorbers from the spectra of QSOs in the Sloan Digital Sky Survey Data Release 1. No evidence is found for the 2175 Å feature which is present in the Milky Way dust extinction curve.

There has been a renewed interest in searching for diffuse interstellar bands (DIBs) due to their probable connection to organic molecules and, thus, their possible link to life in the Universe. Our group is undertaking an extensive search for DIBs in DLAs via QSO absorption-line systems. Six of our DLA targets are presented here. Our equivalent width (EW) limits for the $\lambda$5780 DIB line strongly suggest that DIB abundance is below the Milky Way expected value or that metallicity plays a large role in DIB strengths.