Emergence of red, star-forming galaxies (red misfits) in a {\Lambda}CDM universe

We investigate the formation of red misfits (RM) using a cosmological, hydrodynamical simulation from the $\rm \small EAGLE$ project. Similar to observations, the RM possess less dust, higher stellar metallicities, and older stellar populations compared to blue, star-forming galaxies (BA) at the same $M_\star$. Lagrangian particle-tracking reveals that the older ages of RM have resulted from a combined effect of higher star formation efficiency (SFE), and the earlier onset and faster net depletion of their interstellar medium (ISM). For the centrals, the latter was partially due to higher efficiency of escape from ISM, driven by stronger stellar and/or AGN feedback (depending on the mass). There was an additional contribution to this escape from gas stripping for satellite RM, as suggested by the higher group masses ($\gtrsim 0.5$ dex) and ${\rm H_2}/{\rm H\,{\small I}}$ ratios ($\gtrsim 0.3$ dex). Moreover, accretion of circumgalactic gas (CGM) onto the galaxy has been less efficient for the satellites. On the metallicity front, the offsets are largely due to the disparity in SFE, causing varying degrees of enrichment through the mass-transfers associated with stellar winds and supernovae. We ascribe this SFE disparity to the lower specific angular momentum ($j$) of freshly accreted CGM for RM, which ultimately manifested in the ISM kinematics due to interactions with cooling flows. The impact on $j_{\rm ism}$ was further intensified by poorer alignment with the flow's $\vec{j}$, particularly for the satellites. Our results illuminate potential origins of RM, and motivate further exploration of this peculiar class through a synergy between observations and simulations.Comment: Published in MNRAS. The minor typographical errors have been rectified in this versio

Implications of Introduced Mule Deer on Santa Catalina Island, California : Their Impacts, Population Ecology, and Management

A small group of mule deer were introduced to Santa Catalina Island in the early1930s. The mule deer population increased through the 1940s and 1950s and remains widespread and abundant today. Large browsing ungulates are not native to Santa Catalina Island and there is concern that nonnative mule deer are damaging endemic trees and shrubs on the island when foraging. This study was designed to develop quantitative information on diets, foraging behavior, movements, and population biology of mule deer on Catalina Island. Diet analysis indicated mule deer are consuming a wide variety of native andendemic plants found on Santa Catalina Island in all seasons of the year. Data from browse transects indicated that mule deer consumed all species of trees/shrubs that were available to them, but preferentially foraged on Island mountain mahogany, Island bigpod ceanothus (Ceanothus megacarpus var. insularis), Catalina holly, and chamise (Adenostomafasciculatum). Several of these preferred shrubs lost over 20% of their current annual growth stems during the July to November period when browse represented 70-82% of the diets of mule deer on the island. A particularly compelling manifestation of the negative impacts of nonnative mule deer on island endemic trees/shn1bs was the heavy browse pressure exerted on two species of Catalina Island endemic shrubs (Catalina island bush poppy, Dendromecon harfordii, and felt-leaf ceanothus, Ceanothus arboreus) after several exclosures in the Goat Harbor area were altered to expose several individuals of each shrub to browsing by mule deer. Intensive browsing by mule deer killed one of three felt-leaf ceanothus trees within 15 months of being exposed. Data from 16 seedling plots revealed that physical disturbances by bison and mule deer were the two most important causes of mortality for young oak trees on Catalina Island but browsing by mule deer on oak seedlings did not kill many seedlings outright. I used GPS radio-telemetry collars and resource selection probability functions toidentify areas of the island where high concentrations of deer use overlap known rare plant locations. Mule deer were highly variable in their habitat selection and I found no significant correlation between predicted deer use and locations of rare plants. After estimating the mule deer herd on the island at approximately 2400 deer Iused a stage-based stochastic population model to determine the effects of different harvest strategies on the population dynamics of mule deer on the island. Modeling results indicated harvesting the deer herd at the maximum allowed under the current hunting program will not lead to a sustainable herd. In addition harvesting proportionately more females from the population will be the most efficient method to reduce the population. My models also predict the number of specific age/sex classes of deer ,required to be harvested in order to reduce and maintain the population at 50%, 75%, and 90% of its estimated size in 2006

The relationship between cluster environment and molecular gas content of star-forming galaxies in the EAGLE simulation

We employ the EAGLE hydrodynamical simulation to uncover the relationship between cluster environment and $\rm H_2$ content of star-forming galaxies at redshifts spanning $0\leq z\leq 1$. To do so, we divide the star-forming sample into those that are bound to clusters and those that are not. We find that, at any given redshift, the galaxies in clusters generally have less $\rm H_2$ than their non-cluster counterparts with the same stellar mass (corresponding to an offset of $\lesssim 0.5$ dex), but this offset varies with stellar mass and is virtually absent at $M_\star\lesssim10^{9.3}~{\rm M}_\odot$. The $\rm H_2$ deficit in star-forming cluster galaxies can be traced back to a decline in their $\rm H_2$ content that commenced after first infall into a cluster, which occurred later than a typical cluster galaxy. Evolution of the full cluster population after infall is generally consistent with `slow-then-rapid' quenching, but galaxies with $M_\star\lesssim 10^{9.5}~{\rm M}_\odot$ exhibit rapid quenching. Unlike most cluster galaxies, star-forming ones were not pre-processed in groups prior to being accreted by clusters. For both of these cluster samples, the star formation efficiency remained oblivious to the infall. We track the particles associated with star-forming cluster galaxies and attribute the drop in $\rm H_2$ mass after infall to poor replenishment, depletion due to star formation, and stripping of $\rm H_2$ in cluster environments. These results provide predictions for future surveys, along with support and theoretical insights for existing molecular gas observations that suggest there is less $\rm H_2$ in cluster galaxies.Comment: Accepted for publication in MNRA