Bulletin of the American Physical Society
Mid-Atlantic Section Meeting 2021
Volume 66, Number 18
Friday–Sunday, December 3–5, 2021; Rutgers University, New Brunswick, New Jersey
Session C03: Astrophysics II |
Hide Abstracts |
Chair: Eric Gawiser, Rutgers University Room: 202A |
Saturday, December 4, 2021 9:00AM - 9:36AM |
C03.00001: The Chemical Enrichment and Evolution of Low Mass Galaxies Invited Speaker: Kristen McQuinn Chemical elements, or ``metals'', are produced by stellar nucelosynthesis and redistributed in and around galaxies by exploding stars or supernovae. This chemical enrichment process of galaxies is known to scale with stellar mass in the sense that higher mass galaxies have higher metal content. Theoretical notions have long held that higher mass galaxies are more effecient at making stars and are therefore more chemically enriched whereas low mass galaxies, in addition to being less efficient at turning gas into stars, are also prone to having metals driven out of their shallow potential wells by the energy deposition from supernovae. This is seen in cosmological simulations where stellar feedback-driven galactic winds transport metals from galaxy disks to large distances, with a steep inverse dependence of the amount of metals lost with galaxy mass. In this talk, I will discuss how we are quantitatively testing this framework of stellar feedback and metal loss by (i) measuring the production, distribution, and retention of metals in low-mass galaxies and (ii) using statistical relations and the measured properties of low-mass galaxies to constrain likely chemical evolution pathways. [Preview Abstract] |
Saturday, December 4, 2021 9:36AM - 9:48AM |
C03.00002: Clustering Analysis of Lyman-ɑ Emitters in the COSMOS Field at z=3.1 and z=4.5 Barbara Benda, Eric Gawiser, Rameen Farooq, Shreya Karthikeyan, Adam Broussard, Arjun Dey, Kyoung-Soo Lee, Dustin Lang, Byeongha Moon, Changbom Park, Vandana Ramakrishnan, Frank Valdes, Yujin Yang Lyman alpha emitting galaxies (LAEs) are a useful tool for tracking galaxy evolution. Since the Lyman alpha (Ly$\alpha$) emission line is easily quenched by dust, galaxies detected via this line are nearly dust-free. LAEs are young galaxies in an early burst of star formation that track large scale structure in the distant universe. The One-hundred square-degree DECam Imaging in Narrowbands (ODIN) survey is collecting narrowband images of seven different fields with three filters that correspond to the Ly$\alpha$ line at certain redshifts. Combined with publicly available broadband images, this allows for color selection of LAEs. We use LAE catalogs at z=3.1 and z=4.5 to study spatial clustering of LAEs in the COSMOS field. We measure angular correlation functions for each LAE sample and fit them with a power law minus integral constraint model. We calculate the expected redshift distribution from the LAE luminosity function at the appropriate redshifts and the measured filter bandpass. Using the expected redshift distributions, we will forward-model the predicted dark matter correlations to infer the LAE bias values on large-scales. [Preview Abstract] |
Saturday, December 4, 2021 9:48AM - 10:00AM |
C03.00003: Testing Conformity in the Local Group and Local Volume Charlotte Olsen, Eric Gawiser Conformity denotes the correlation of properties e.g., star formation rate (SFR), specific star formation rate (sSFR), quenched fraction, etc. between pairs of galaxies as a function of separation. This correlation has implications for the impact of environment upon galaxy formation and evolution. Conformity between central galaxies and satellites within the same dark matter halo has been well documented both in simulations and observations. However, the existence of conformity at much greater distances -- known as two-halo conformity -- remains uncertain. Olsen et al. (2021) found synchronized star formation in star formation histories of Local Volume dwarf galaxies. Since these galaxies are separated by as much as 8 Mpc, the cause of this apparent co-evolution is unclear. We investigate whether this sample, combined with Local Group galaxies, reveals two-halo conformity by examining sSFR, SFR, stellar mass, and quenched fraction as a function of physical separation. Making use of the star formation histories of these galaxies, we then extend this analysis back in time by up to 6 Gyr to offer the first probe of conformity through cosmic time. [Preview Abstract] |
Saturday, December 4, 2021 10:00AM - 10:12AM |
C03.00004: Using a Neural Network Classifier to Select Galaxies with the Most Accurate Photometric Redshifts Adam Broussard, Eric Gawiser The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will produce several billion photometric redshifts (photo-$z$'s), enabling cosmological analyses that use subsets of galaxies with the most accurate photo-$z$'s. We perform initial redshift fits on Subaru Strategic Program galaxies with imaging in $grizy$ optical and near-infrared bands using Trees for Photo-Z (TPZ) before applying a custom neural network classifier (NNC) tuned to select galaxies with accurate photo-$z$'s. We consider four cases of training and test sets ranging from an idealized case to using data augmentation to increase the representation of dim galaxies in the training set. We find significant further improvements when selecting galaxies using the NNC over selections made using TPZ uncertainties, including a 35\% improvement in outlier rate and a 23\% improvement in photo-$z$ scatter ($\sigma_z$). This method can be tuned to retain a particular sample size or to achieve a desired photo-$z$ accuracy; our results show that it is possible to retain more than a third of an LSST-like galaxy sample while reducing $\sigma_z$ by a factor of two compared to the full sample, with one-fifth as many photo-$z$ outliers. [Preview Abstract] |
Saturday, December 4, 2021 10:12AM - 10:24AM |
C03.00005: SALT Data Reduction for Multi-Slit Spectroscopy George Kharchilava, Elisabeth Turner, Adam Broussard, Eric Gawiser Spectroscopic data reduction is necessary to fully identify emission lines from distant galaxies. There are various limitations that need to be addressed in order to effectively prepare spectroscopic images for scientific analysis such as cosmic ray exposure, variations in instrumental response, and sky background emission. To minimize these limitations, we develop a reduction pipeline to process multi-slit spectroscopic data taken by the Southern African Large Telescope (SALT). Each set of data comes in the form of science images, flat-field images, and an arc lamp image. We use flat-fielding to correct for variations in instrumental response, then cosmic ray removal is performed, followed by stacking of the science images. Stacked images are then calibrated for both wavelength and flux sensitivity. Once the data are successfully reduced, a plot of flux versus wavelength can be created to show the various emission lines present from distant galaxies. By analyzing spectra of galaxies, emission lines for our sample can be identified as either Lyman-alpha or ionized oxygen, and fitted to determine galaxy physical properties including electron densities, ionization parameters, velocity dispersion, dust reddening, metallicities, and star formation rates. [Preview Abstract] |
Saturday, December 4, 2021 10:24AM - 11:00AM |
C03.00006: Ex Luna Scientia! Nuclear Astrophysics Enabled by the Lunar Occultation eXplorer (LOX) Invited Speaker: Richard Miller LOX is a focused science mission that will, for the first time, perform systematic population studies of thermonuclear, or type-Ia, supernova (SNeIa) using their emergent nuclear radiation. LOX will achieve this by probing the fundamental nuclear processes that govern these ``beacons of the Cosmos''. LOX measurements of the radioactivity left behind in the wake of nuclear burning will reveal characteristic trends via population studies that individual detections cannot, further our understanding of the matter--energy life cycles within galaxies, and provide critical diagnostic evidence for the multiple evolutionary pathways responsible this class of supernovae. LOX will directly test the assumption of SNeIa homogeneity. Open questions in cosmology (e.g., cosmic expansion history, dark energy) and astrophysics (e.g., the details of the nucleosynthetic yields) requires us to understand the fundamental nature of these objects and their progenitors. LOX will achieve its science goals with a simple, low-cost, cross-cutting implementation. LOX employs a single-instrument payload consisting of an array of identical gamma-ray sensor modules. The instrument design and its single mode of operation leverage decades of heritage derived from planetary exploration endeavors. The LOX implementation approach mitigates the challenges associated with increasingly complex space-based instrumentation. LOX leverages the power of continuous all-sky monitoring to meet its science goals. Therefore, LOX fills a long-standing astrophysical capability gap. In fact, as the first high-sensitivity MeV astrophysics mission in a generation, it has a significant capacity for discovery beyond our primary SNeIa science goals. LOX is currently being prepared for submission to NASA's astrophysics MIDEX program, and with it NASA will establish the Moon as a platform for science and once again pry open a new window on the Cosmos. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700