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Long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe) are expected to result from massive star deaths. However to date, there has been no direct observational measurement of their cloud collapse timescales nor progenitor lifetimes to help constrain their mass. Our analyses of z 2 LGRB afterglow spectra and Hubble Space Telescope images find a higher fraction of host galaxies that are interacting, have a close companion, and/or may have experienced a recent galaxy 'fly by' as compared to the general z 2 galaxy population. A smaller set of z 2 SLSNe suggests a similar result. Under the hypothesis that galaxy interactions induce cloud collapse and star formation near their closest approach, we explore measurements of the host and companion galaxy velocities and separations at the time of the LRGB/SLSN event as a direct physical means to measure the timescale of cloud collapse plus progenitor star lifetime. [ABSTRACT FROM AUTHOR]

Long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe) are expected to result from massive star deaths. However to date, there has been no direct observational measurement of their cloud collapse timescales nor progenitor lifetimes to help constrain their mass. Our analyses of z 2 LGRB afterglow spectra and Hubble Space Telescope images find a higher fraction of host galaxies that are interacting, have a close companion, and/or may have experienced a recent galaxy 'fly by' as compared to the general z 2 galaxy population. A smaller set of z 2 SLSNe suggests a similar result. Under the hypothesis that galaxy interactions induce cloud collapse and star formation near their closest approach, we explore measurements of the host and companion galaxy velocities and separations at the time of the LRGB/SLSN event as a direct physical means to measure the timescale of cloud collapse plus progenitor star lifetime. [ABSTRACT FROM AUTHOR]

Metal absorption systems are products of star formation. They are believed to be associated with massive star-forming galaxies, which have significantly enriched their surroundings. To test this idea with high column density C iv absorption systems at z ∼ 5.7, we study the projected distribution of galaxies and characterize the environment of C iv systems in two independent quasar lines of sight: J103027.01+052455.0 and J113717.73+354956.9. Using wide-field photometry (∼80 × 60 h−1 comoving Mpc), we select bright (MUV(1350 Å) ≲ −21.0 mag.) Lyman break galaxies (LBGs) at z ∼ 5.7 in a redshift slice Δz ∼ 0.2 and we compare their projected distribution with z ∼ 5.7 narrow-band selected Lyman alpha emitters (LAEs, Δz ∼ 0.08). We find that the C iv systems are located more than 10 h−1 projected comoving Mpc from the main concentrations of LBGs and no candidate is closer than ∼5 h−1 projected comoving Mpc. In contrast, an excess of LAEs – lower mass galaxies – is found on scales of ∼10 h−1 comoving Mpc, suggesting that LAEs are the primary candidates for the source of the C iv systems. Furthermore, the closest object to the system in the field J1030+0524 is a faint LAE at a projected distance of 212 h−1 physical kpc. However, this work cannot rule out undiscovered lower mass galaxies as the origin of these absorption systems. We conclude that, in contrast with lower redshift examples (z ≲ 3.5), strong C iv absorption systems at z ∼ 5.7 trace low-to-intermediate density environments dominated by low-mass galaxies. Moreover, the excess of LAEs associated with high levels of ionizing flux agrees with the idea that faint galaxies dominate the ionizing photon budget at this redshift. [ABSTRACT FROM AUTHOR]

The detection of Population III (Pop III) supernovae (SNe) could directly probe the primordial initial mass function for the first time, unveiling the properties of the first galaxies, early chemical enrichment and reionization, and the seeds of supermassive black holes. Growing evidence that some Pop III stars were less massive than 100M☉ may complicate prospects for their detection, because even though they would have been more plentiful, they would have died as core-collapse SNe, with far less luminosity than pair-instability explosions. This picture greatly improves if the SN shock collides with a dense circumstellar shell ejected during a prior violent luminous blue variable type eruption. Such collisions can turn even dim SNe into extremely bright ones whose luminosities can rival those of pair-instability SNe.We present simulations of Pop III Type IIn SN light curves and spectra performed with the Los Alamos RAGE and SPECTRUM codes. Taking into account Lyα absorption in the early universe and cosmological redshifting, we find that 40M☉ Pop III Type IIn SNe will be visible out to z ~ 20 with the James Webb Space Telescope and out to z ~ 7 with WFIRST. Thus, even low mass Pop III SNe can be used to probe the primeval universe. [ABSTRACT FROM AUTHOR]

ABSTRACT We use a sample of z ∼ 3 Lyman-break galaxies (LBGs) to examine close pair clustering statistics in comparison to Λ cold dark matter (ΛCDM)-based models of structure formation. Samples are selected by matching the LBG number density, ng, and by matching the observed LBG 3D correlation function of LBGs over the two-halo term region. We show that ultraviolet (UV) luminosity abundance matching cannot reproduce the observed data, but if subhaloes are chosen to reproduce the observed clustering of LBGs we are able to reproduce the observed LBG pair fraction ( Nc) defined as the average number of companions per galaxy. This model suggests an overabundance of LBGs by a factor of ∼5 over those observed, suggesting that only one in five haloes above a fixed mass hosts a galaxy with LBG-like UV luminosity detectable via LBG selection techniques. This overdensity is in agreement with the results of a Millennium 2 analysis and with the discrepancies noted by previous authors using different types of simulations. We find a total observable close pair fraction of 23 ± 0.6 per cent (17.7 ± 0.5 per cent) using a prototypical cylinder radius in our overdense fiducial model and 8.3 ± 0.5 per cent (5.6 ± 0.2 per cent) in an abundance matched model (impurity corrected). For the matched spectroscopic slit analysis, we find [ABSTRACT FROM AUTHOR]

Investigations of interacting and merging galaxies at high redshift are vital to our understanding of their formation and evolution. To date, the identification of interactions at and above has relied on rest-frame ultraviolet morphological parameters. Here, we present five serendipitous spectroscopic Lyman break galaxy (LBG) pairs with projected proper separations in our survey of nine separate deep Keck fields. The data consist of 140 of our highest signal-to-noise ratio LBG spectra and ∼500 of our most confident colour-selected LBGs. We show that the pairs are composed of two distinct close and/or interacting LBGs from a detailed analysis of the rest-frame ultraviolet 1D and 2D spectra and the deep broad-band images. In addition, we show that the number and separation distribution of the pairs is expected from (1) the two-point angular correlation function when applied to the LBG pair separation distribution in our survey and ∼2500 colour-selected LBGs from the literature and (2) an analysis of a carefully matched high-resolution hybrid numerical and analytical cosmological simulation. Because the spectroscopic slitlets have random orientations with respect to the close pairs on the sky, the serendipitous pairs provide an unbiased sampling of the underlying close pair fraction. Finally, we discover two Lyα emitters (LAEs) in our slitlets and find that they reside within 50 projected of the spectroscopic LBGs. In this work, we uncover a strong relationship between Lyα emission and pair separation. All confirmed and all candidate LBG pairs with separations of ≤15 projected exhibit Lyα in emission and we find an indication of an overabundance of Lyα emission in pairs with ≤50 projected separations. This relationship suggests a picture in which a measurable fraction of the Lyα emission of LBGs, and potentially LAEs, is generated via interaction mechanisms such as triggered star formation and the dispersal of obscuring gas and dust. As a result, serendipitous spectroscopic close pairs provide a unique means to help identify and study high-redshift galaxy interactions using ground-based optical data. [ABSTRACT FROM AUTHOR]