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We present a complete census of all Herschel-detected sources within the six massive lensing clusters of the HST Frontier Fields (HFF). We provide a robust legacy catalogue of 263 sources with Herschel fluxes, primarily based on imaging from the Herschel Lensing Survey and PEP/HerMES Key Programmes. We optimally combine Herschel, Spitzer and WISE infrared (IR) photometry with data from HST, VLA and ground-based observatories, identifying counterparts to gain source redshifts. For each Herschel-detected source we also present magnification factor (mu), intrinsic IR luminosity and characteristic dust temperature, providing a comprehensive view of dust-obscured star formation within the HFF. We demonstrate the utility of our catalogues through an exploratory overview of the magnified population, including more than 20 background sub-LIRGs unreachable by Herschel without the assistance gravitational lensing.

Compact groups of galaxies provide insight into the role of low-mass, dense environments in galaxy evolution because the low velocity dispersions and close proximity of galaxy members result in frequent interactions that take place over extended time-scales. We expand the census of star formation in compact group galaxies by Tzanavaris et al. (2010) and collaborators with Swift UVOT, Spitzer IRAC and MIPS 24 mu m photometry of a sample of 183 galaxies in 46 compact groups. After correcting luminosities for the contribution from old stellar populations, we estimate the dust-unobscured star formation rate (SFRUV) using the UVOT uvw2 photometry. Similarly, we use the MIPS 24 mu m photometry to estimate the component of the SFR that is obscured by dust (SFRIR). We find that galaxies which are MIR-active (MIR-'red'), also have bluer UV colours, higher specific SFRs, and tend to lie in H I-rich groups, while galaxies that are MIR-inactive (MIR-'blue') have redder UV colours, lower specific SFRs, and tend to lie in H I-poor groups. We find the SFRs to be continuously distributed with a peak at about 1 M-circle dot yr(-1), indicating this might be the most common value in compact groups. In contrast, the specific SFR distribution is bimodal, and there is a clear distinction between star-forming and quiescent galaxies. Overall, our results suggest that the specific SFR is the best tracer of gas depletion and galaxy evolution in compact groups.

In this research water emission is modeled from intermediate mass star formations regions placed at 1 kpc. Nine models are created to describe these regions of varying source luminosity ($L=100,500,$ and $1000L_{\odot}$) and protostellar envelope mass ($M=10,100,$ and $500M_{\odot}$). For each model, an intermediate mass class 0 protostar is centrally embedded in a spherically symmetry static protostellar envelope. Radiation transfered through these regions is calculated using the program RATRAN that applies an accelerated Monte Carlo method to obtain level population profiles of water. The level populations are used to determine the emission distribution of water from the regions by using a ray tracing method. Strong correlations between line ratios, integrated intensities and source luminosity are found. Larger envelope masses resulted in more mass going in the outer envelope where the water is frozen and does not contribute to the water emission and absorption. Line strengths, ratios, and integrated intensities for all the spectral lines of water within Herschel's observation range are tabulated.

In this research water emission is modeled from intermediate mass star formations regions placed at 1 kpc. Nine models are created to describe these regions of varying source luminosity ($L=100,500,$ and $1000L_{\odot}$) and protostellar envelope mass ($M=10,100,$ and $500M_{\odot}$). For each model, an intermediate mass class 0 protostar is centrally embedded in a spherically symmetry static protostellar envelope. Radiation transfered through these regions is calculated using the program RATRAN that applies an accelerated Monte Carlo method to obtain level population profiles of water. The level populations are used to determine the emission distribution of water from the regions by using a ray tracing method. Strong correlations between line ratios, integrated intensities and source luminosity are found. Larger envelope masses resulted in more mass going in the outer envelope where the water is frozen and does not contribute to the water emission and absorption. Line strengths, ratios, and integrated intensities for all the spectral lines of water within Herschel's observation range are tabulated.

The majority of galaxy formation studies which explore beyond local redshifts do not typically probe down to the dwarf galaxy stellar mass range of ∼ 10^9 Msun . Thus trends in the observed evolution or characteristics of galaxy formation at a particular epoch are based upon populations of massive galaxies. However the currently favored Λ-Cold Dark Matter (Λ-CDM) theory is based upon hierarchical clustering and merging of lower mass systems, which proceed to make the higher mass, complex morphology of galaxies we observe. Thus it is clear that within the dwarf galaxy mass regime there should be a significant phase of galaxy formation and evolution. This work aims to uncover the influence of local environment on the formation and evolution of dwarf and massive galaxies beyond local redshift, probing down to a mass range lower than that which has been explored by previous studies. A previously successful study titled the Redshift One LDSS-3 Emission line Survey (ROLES), released results for a redshift of z ∼ 1, which compared the [OII] luminosity and galaxy stellar mass functions ([OII] LF and GSMF respectively), star formation rate density (SFRD), and specific star formation rate (sSFR) relations, with a local SDSS dataset. This led to the expansion of the study to lower redshift (this work) which explored low stellar mass galaxies at a redshift of z ∼ 0.75. This follow-up study referred to as ROLES75 (z ∼ 0.75) targeted the same two deep fields explored by the z ∼ 1 study (GOODS-South, MS1054-03 FIRES), which have extensive public photometry. Low mass targets were selected for study by their K-magnitudes (22.5 < KAB < 24) leading to a dwarf mass range of 8.5 < Log(M∗/Msun) < 9.5, and which were most likely to be within our redshift range (0.62 < z < 0.885). Follow-up multi-object spectroscopy targeted the [OII]λ3727A emission line star formation tracer in these targets allowing us to identify and obtain secure spectroscopic redshifts, SED-fit stellar masses and observed [OII] luminosity calibrated star formation rates down to limits of Log(M∗/Msun) ∼ 8.85 and SFR ∼ 0.1 Msun/yr . Science results presented here are similar to those published by the ROLES z ∼ 1 study, however we also studied the influence of the high versus low density environment in which the galaxy populations reside. This study confirmed that while the [OII] luminosity was higher in earlier times, environment does not influence galaxy formation at z ∼ 0.75. The faint-end slope of the [OII] LF, α ∼ 1.25 measured here, is also observed to become increasingly more steep with increasing redshift. The [OII] luminous GSMF is observed to not have significantly evolved since z ∼ 2.75, confirming the result of the previous ROLES work. However the impact of environment on the GSMF is apparent in the high mass end where the imprint of structure from the CDFS field enhances the stellar mass function above the field population. There is also weak evidence of a bi-modal [OII] luminous GSMF indicated by an ‘upturn’ near ∼ 10^9 Msun in the low density field population. The SFRD at z ∼ 0.75 does not confirm the picture presented by the ROLES z ∼ 1 study where a constant scale factor was applicable to the local SDSS SFRD to obtain the z ∼ 1 SFRD. The SFRD in the high mass end at z ∼ 0.75 is lower than would be expected based upon a constant scale factor, while the low stellar mass end exhibits some consistency with this picture. In the high density environment, this dominant SFRD (over the low density field population) is driven by the high density [OII] luminous GSMF in the high stellar mass end, rather than through an enhancement of the SFR. The normalization of the sSFR − M∗ relation at z ∼ 0.75 is found to lie between those corresponding to z ∼ 1 and present day. There is a subtle ‘upturn’ in the sSFR − M∗ relation confirming this observation which was also present in the ROLES z ∼ 1 study but not present in the local SDSS sSFR − M∗ relation. The sSFR of active galaxies does not depend upon the local density in which they are forming, confirming the same conclusion based upon the [OII] LF. However, there is redshift evolution of the sSFR − M∗ relation with respect to local density. The high density sSFR − M∗ relation for star forming galaxies was dominant over its low density counterpart at early times, with the opposite the case at present day. There is suggestion of the crossover or rollover transition occurring at z ∼ 0.75.

The properties of planet-forming midplanes of protostellar disks remain largely unprobed by observations due to the high optical depth of common molecular lines and continuum. However, rotational emission lines from rare isotopologues may have optical depth near unity in the vertical direction, so that the lines are strong enough to be detected, yet remain transparent enough to trace the disk midplane. In this thesis, we present a chemical model of an MRI-active protoplanetary disk including different C, O isotopes and detailed photochemical reactions. The CO condensation front is found to be at 1.5 AU on the disk midplane around a solar like star, and its location remains almost unchanged during 3Myr of evolution. The optical depth of low-order rotational lines of C¹⁷O are around unity, which suggests it may be possible to see into the disk midplane using C¹⁷O. Such ALMA observations would provide estimates of the disk midplane temperature if the CO ice lines were spatially or spectrally resolved. With our computed C¹⁷O/H₂ abundance ratio, one would also be able to measure the disk masses by measuring the intensity of gas emission. / text

Studies of central black holes (BHs) in nearby galaxies revealed tight correlation between the BH mass the host galaxy bulge mass, indicating a link between BH and star formation (SF) in the host galaxy. Luminous active galactic nuclei (AGN) are powered by mass accretion onto supermassive BHs. Observations of the AGNs and the SF in their host galaxies are required to understand their relation and how they establish this BH mass-galaxy bulge mass correlation over a wide range of cosmic lookback times. This thesis presents a survey of 24 μm-selected luminous AGN and their host galaxies up to z ~ 3.2. It focuses on the foreground and background broad line (Type-1) and narrow line (Type-2) AGNs of 30 massive galaxy cluster fields with total survey area of 5.2 deg², using the multi-wavelength dataset from the ultraviolet (UV) to far infrared (FIR) from the Local Cluster Substructure Survey. The AGN sample is nearly complete to a 1 mJy flux cutoff at 24 μm, and is optical-spectroscopically identified. With this dataset and the accompanying MMT/Hectospec spectroscopy survey, the properties of AGNs such as BH masses, BH accretion rates, and total luminosities, can be readily determined. Particularly, the Herschel data (100, 160, 250, 350, and 500 μm) sample the FIR peak of sources in our sample, and provide constraints on the star formation rates (SFR) in the host galaxies. For the Type 1 AGN sample, most of the systems are at z > 0.6 with luminosities > 10^45 ergs/s. Out of the 205 Type-1 AGNs, 107 are detected in at least two Herschel bands. We use AGN, stellar, and SF galaxy templates to decompose their spectral energy distributions (SEDs) from the UV to the FIR, and estimate their IR SF luminosities, AGN luminosities, and their host galaxy stellar masses. The SED decomposition reveals that a high level of SF is ubiquitous for our 24 μm-selected Type-1 AGN sample. For sources at z < 1, the stellar components from SED decomposition provide direct constraints on the stellar mass. For sources at z > 1, the BH mass-bulge stellar mass correlation is used for indirect constraints on the stellar mass. We carried out a similar analysis on the 85 Type-2 AGNs and their host galaxies up to z ~ 0.8, out of which 55 are detected in at least two Herschel bands. We reach the same conclusion as for the Type 1 AGN sample. That is, 1) These AGN host galaxies are very massive, and the vast majority of these galaxies have specific star formation rates (SSFR) consistent with those of main-sequence, star-forming galaxies rather than starbursting galaxies; 2) Most of these AGNs accrete at a rate close to 10% of Eddington; 3) We also find a strong correlation between the IR luminosity of the SF component and the AGN total luminosity, for both Type 1 and Type 2 AGNs. However, we show that the correlation could arise just because the BH mass (and hence AGN total luminosity) and the SF are both correlated with the galaxy mass, rather than requiring a causal connection between the observed rates of SF and the nuclear activity.

This thesis presents multi-frequency data, galaxy identifications, estimated redshifts, and derived physical properties for the sub-millimetre source sample produced by the SCUBA HAlf Degree Extragalactic Survey (SHADES). SHADES is the largest, complete, sub-millimetre survey undertaken to date, and the aim of this work is to exploit this survey to study the evolution of sub-mm selected galaxies at high redshift, explore their possible connectionwith localmassive ellipticals, and to test current models of galaxy formation. The SHADES sample was selected from 850 micron images made with the submillimetre camera SCUBA at the James Clerk Maxwell Telescope. These submillimetre maps cover a total area of 720 arcmin2 split between two well-studied extra-galactic survey fields, the Lockman Hole East and the Subaru/XMMNewton Deep Field (SXDF). The resulting sample of 120 sub-millimetre sources is the focus of this thesis. Here the wealth of information provided by deep radio, optical, near-infrared and mid-infrared imaging of the two SHADES fields is exploited to complete the identification of the SHADES sample, and then to derive a robust redshift estimate for every sub-millimetre source. Where possible this is achieved from the optical+ infrared photometry using a new two-component redshift estimation code developed specifically to deal with starbursting galaxies with potentially highly stochastic star-formation histories. The effectiveness of this code is demonstrated via comparison with the small subset of SHADES source which possess robust spectroscopic redshifts. For those galaxies which are too faint for effective redshift constraints to be provided by the existing optical+infrared photometry, the information on the long-wavelength spectral energy distribution provided by the radio+submm photometry is utilised to provide cruder constraints or limits on redshift. The result is the first complete and unbiased estimate of the redshift distribution of the bright extragalactic sub-millimetre galaxy population. It is found that the brightest sub-mm sources are confined to the redshift range 2 < z < 4, while more moderate luminosity sources span the full range of redshift out to z ∼ 5. The fits to themulti-frequency photometry provided by the redshift estimation technique are also used to derive estimates of the stellar mass, and star-formation history of each SHADES galaxy. The average derived stellar mass is ∼ 3 × 1011 M⊙ and it is found that the violent starburst powering the sub-millimetre emission typically contributes less than 10% of the stellar mass of the galaxy which has been assembled prior to the “current” starburst event. The distributions of redshift, stellar mass, and star-burst ages are compared with the predictions of a range of galaxy models, including the suite of models originally used to motivate the SHADES survey in van Kampen et al. (2005), and themost recent incarnation of the Durhamsemi-analytic galaxy formationmodels described by Swinbank et al. (2008). It is found that the redshift distribution and sub-mmflux versus redshift for bright sub-mmgalaxies can be reproduced best by one of the van Kampen models, which is based on semi-analytic modelling with a Chabrier IMF. We can rule out the non-semi-analytic prediction models and the Durham semi-analytic model with a top-heavy IMF. However the stellar masses are systematically underpredicted by all of the models. Either the stellar masses derived from the SHADES data have been systematically over-estimated, or the models need to be modified (perhaps by the inclusion of AGN feedback) to allow larger galaxy masses to assembled prior to z ∼ 2. Finally, it is demonstrated that themass in place prior to the observed starburst cannot have been produced by an analogous super-burst at higher redshift, but rather requires to have been assembledmore gradually over a timescale of ∼ 1−2 Gyr. It is thus concluded thatmassive galaxies undergo theirmost violent phase of star formation at redshifts 2 < z < 4, but that the enormous starbursts which lead to detection in current sub-millimetre surveys can only take place in the potential well provided by an already massive galaxy. This supports a scenario in which bright sub-millimetre galaxies are indeed the progenitors of the massive elliptical galaxies found in the local Universe.