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Cameron Lawlor-Forsyth

Publications and source records attributed to Cameron Lawlor-Forsyth.

6 recordsLinked to original sources

Identifying and Distinguishing Quenching Galaxies with Spatially Resolved Star Formation in the Hubble Frontier Fields

We investigate the nature and prevalence of different quenching signatures for 1437 galaxies with $M_{*} \geqslant 10^{8}~\mathrm{M}_{\odot}$ and $\text{SFR} \geqslant 10^{-3}~M_{\odot}~\text{yr}^{-1}$ in the Hubble Frontier Fields through spatially resolved spectral energy distribution fitting with \texttt{FAST++}. We use the morphological metrics previously presented in our series of investigations to quantify the distribution of star formation, and use a $k$-nearest neighbors algorithm to classify quenching galaxies into different quenching pathways, including an inside-out pathway and an outside-in pathway. We find 129 galaxies have morphologies consistent with an inside-out quenching pathway, and 70 are consistent with an outside-in pathway. Inside-out quenching galaxies are $0.8^{+0.2}_{-0.1}~\text{dex}$ more massive compared to outside-in quenching galaxies, where both populations are more massive in clusters than the field, by $0.8^{+0.3}_{-0.1}~\text{dex}$. Inside-out quenching galaxies are found more often in clusters (106/129), compared to outside-in quenching galaxies (25/70). In clusters, the fraction of inside-out quenching galaxies strongly increases with mass, representing ${\sim}$30% of the non-quenched galaxy population at high masses. A milder evolution is seen in the field. The fraction of outside-in quenching galaxies is independent of mass, representing ${\lesssim}$10% of the non-quenched population, in both the cluster and field. We find no strong dependence for the fraction of any population with estimated infall time, except massive inside-out quenching galaxies, which increase in fraction with increasing infall time.

astro-ph.GA

Estimating Cluster Galaxy Infall Time from Phase Space in TNG

Using the TNG300 and TNG-Cluster simulations, phase space-based estimates for galaxy infall time onto clusters with $M_{\mathrm{h}} \geqslant 10^{14}~M_{\odot}$ are determined for all simulation snapshots with $z \leqslant 1$. These infall time estimates are consistent with previous work in the literature, and can be readily applied to observations of cluster galaxies, where no other estimate is feasible, based only on the galaxy's position in projected phase space. The analysis pipeline used to produce these infall time estimates is publicly released, as are the resulting data products, as well as a tutorial that outlines their use. It is anticipated that both the data products and the provided tutorial will facilitate future research within the community which require infall time estimates, and will provide an additional baseline for studies investigating the orbital histories of galaxies in dense environments like galaxy clusters.

astro-ph.GA

Identifying and Distinguishing Quenching Galaxies with Spatially Resolved Star Formation in Mock CASTOR and NGRST Observations

We present synthetic images of galaxies that are in the stages of star formation quenching for the Cosmological Advanced Survey Telescope for Optical and UV Research (CASTOR) and Nancy Grace Roman Space Telescope (NGRST), based on simulations coming from the IllustrisTNG suite, as processed using the stellar population synthesis library \textsc{galaxev}. We account for the effects of dust and various sources of noise to produce mock observations that should mirror real observations. Using these synthetic images, we fit photometric observations in binned circular annuli using \texttt{FAST++} and a flexible star formation history, and recover well the spatially resolved stellar mass and star formation rate. We thereby measure various indicators (morphological metrics) of spatially resolved star formation activity in the context of galaxy quenching. We find that we are able to distinguish quenching galaxies from a mass-matched control sample of normal star forming galaxies. We additionally find that we can distinguish various quenching mechanisms, where galaxies consistent with an inside-out quenching signature can be separated from galaxies that display an outside-in signature. Using machine learning techniques the accuracy of this classification is reliable, and the progress through the quenching episode can be estimated for the different populations of quenching galaxies. We make predictions for the abundance of the various quenching populations in proposed surveys for CASTOR and NGRST, and find that these surveys will enable the classifications of thousands of quenching galaxies out to intermediate redshifts, and more when considering higher redshifts.

astro-ph.GA

Identifying and distinguishing quenching galaxies with spatially resolved star formation in TNG50

Using the TNG50 simulation, we determine observationally motivated metrics that can distinguish quenching galaxies from star forming galaxies for $M_{*} \geqslant 10^{9.5}~M_{\odot}$, based on the spatial distribution of their stellar populations. Quenching galaxies are not fully quenched but have low levels of ongoing star formation that decreases over time. The morphological metrics consider the concentration of star formation, size of the star forming disk, and characteristic radii that trace sharp truncations of star formation. These metrics can separate simulated quenching galaxies based on morphology into populations where star formation is suppressed inside-out and outside-in. Inside-out quenched galaxies are more likely to be the most massive galaxy within their halo in the field, while outside-in quenched galaxies are satellites residing in dense environments and begin quenching ${\sim} 1~\text{Gyr}$ after being accreted. Outside-in quenched galaxies typically take ${\sim} 1.5~\text{Gyr}$ to quench, and inside-out quenched galaxies can take up to ${\sim} 3.5~\text{Gyr}$, where the duration of quenching is a function of stellar mass. We find that each population of quenched galaxy experiences evolution of their morphological metrics, where the different quenched populations reside in unique locations in parameter space. Galaxies in the later stages of quenching are more easily distinguished than those in the early stages, when compared to star forming galaxies. In addition, inside-out quenched galaxies can be distinguished compared to outside-in quenched galaxies, and the progress through the quenching episode can be estimated for both populations. These results have broad implications for distinguishing quenching galaxies in large galaxy surveys.

astro-ph.GA

FORECASTOR -- I. Finding Optics Requirements and Exposure times for the Cosmological Advanced Survey Telescope for Optical and UV Research mission

The Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR) is a proposed Canadian-led 1m-class space telescope that will carry out ultraviolet and blue-optical wide-field imaging, spectroscopy, and photometry. CASTOR will provide an essential bridge in the post-Hubble era, preventing a protracted UV-optical gap in space astronomy and enabling an enormous range of discovery opportunities from the solar system to the nature of the Cosmos, in conjunction with the other great wide-field observatories of the next decade (e.g., Euclid, Roman, Vera Rubin). FORECASTOR (Finding Optics Requirements and Exposure times for CASTOR) will supply a coordinated suite of mission-planning tools that will serve as the one-stop shop for proposal preparation, data reduction, and analysis for the CASTOR mission. We present the first of these tools: a pixel-based, user-friendly, extensible, multi-mission exposure time calculator (ETC) built in Python, including a modern browser-based graphical user interface that updates in real time. We then provide several illustrative examples of FORECASTOR's use that advance the design of planned legacy surveys for the CASTOR mission: a search for the most massive white dwarfs in the Magellanic Clouds; a study of the frequency of flaring activity in M stars, their distribution and impacts on habitability of exoplanets; mapping the proper motions of faint stars in the Milky Way; wide and deep galaxy surveys; and time-domain studies of active galactic nuclei.

astro-ph.IM

Ionized Gas Outflows in Low Excitation Radio Galaxies Are Radiation Driven

Low excitation radio galaxies (LERGs) are weakly accreting active galactic nuclei (AGN) believed to be fuelled by radiatively inefficient accretion processes. Despite this, recent works have shown evidence for ionized and neutral hydrogen gas outflows in these galaxies. To investigate the potential drivers of such outflows we select a sample of 802 LERGs using the Best & Heckman (2012) catalogue of radio galaxies. By modelling the [O III] $λ5007$ profile in Sloan Digital Sky Survey spectra of a sample of 802 LERGs, we determine that the ionized outflows are present in $\sim 1.5\%$ of the population. Using $1.4~\text{GHz}$ imaging from the Faint Images of the Radio Sky at Twenty Centimeters survey we analyze the radio morphology of LERGs with outflows and find these to be consistent with the parent LERG population. However, we note that unlike the majority of the LERG population, those LERGs showing outflows have Eddington scaled accretion rates close to $1\%$. This is indicative that ionized outflows in LERGs are driven by the radiation pressure from the accretion disk of the AGN rather than the radio jets. We report specific star formation rates in the range of $10^{-12} < \text{sSFR} < 10^{-9}~\text{yr}^{-1}$. Moreover, we observe higher mass outflow rates of $7-150~M_{\odot}~\text{yr}^{-1}$ for these LERGs than luminous quasars for a given bolometric luminosity, which could possibly be due to the radio source in LERGs boosting the mass-loading. This scenario could indicate that these outflows could potentially drive feedback in LERGs.

astro-ph.GA