Lyman Break Galaxies at z = 4 - 6 in cosmological SPH Simulations

We perform a spectrophotometric analysis of galaxies at redshifts z = 4 - 6 in cosmological SPH simulations of a Lambda CDM universe. Our models include radiative cooling and heating by a uniform UV background, star formation, supernova feedback, and a phenomenological model for galactic winds. Analysing a series of simulations of varying boxsize and particle number allows us to isolate the impact of numerical resolution on our results. Specifically, we determine the luminosity functions in B, V, R, i', and z' filters, and compare the results with observed galaxy surveys done with the Subaru telescope and the Hubble Space Telescope. We find that the simulated galaxies have UV colours consistent with observations and fall in the expected region of the colour-colour diagrams used by the Subaru group. Assuming a uniform extinction of E(B-V) = 0.15, we also find reasonable agreement between simulations and observations in the space density of UV bright galaxies at z = 3 - 6, down to the magnitude limit of each survey. For the same moderate extinction level of E(B-V) ~ 0.15, the simulated luminosity functions match observational data, but have a steep faint-end slope with alpha ~ -2.0. We discuss the implications of the steep faint-end slope found in the simulations.Comment: 13 pages, 16 figures, MNRAS in pres

The Sunday Night Black & White 6

A compilation zine featuring black and white art and short form narrative.https://source.sheridancollege.ca/unique_collections_snb/1005/thumbnail.jp

Characterization of Microlensing Planets with Moderately Wide Separations

In future high-cadence microlensing surveys, planets can be detected through a new channel of an independent event produced by the planet itself. The two populations of planets to be detected through this channel are wide-separation planets and free-floating planets. Although they appear as similar short time-scale events, the two populations of planets are widely different in nature and thus distinguishing them is important. In this paper, we investigate the lensing properties of events produced by planets with moderately wide separations from host stars. We find that the lensing behavior of these events is well described by the Chang-Refsdal lensing and the shear caused by the primary not only produces a caustic but also makes the magnification contour elongated along the primary-planet axis. The elongated magnification contour implies that the light curves of these planetary events are generally asymmetric and thus the asymmetry can be used to distinguish the events from those produced by free-floating planets. The asymmetry can be noticed from the overall shape of the light curve and thus can hardly be missed unlike the very short-duration central perturbation caused by the caustic. In addition, the asymmetry occurs regardless of the event magnification and thus the bound nature of the planet can be identified for majority of these events. The close approximation of the lensing light curve to that of the Chang-Refsdal lensing implies that the analysis of the light curve yields only the information about the projected separation between the host star and the planet.Comment: 4 pages, 2 figure