Insights Into Star Formation and AGN Activity in Protocluster Environments From Morphological Studies and SED Fitting

In this dissertation I present work done from 2018-2023 to investigate the growth of galaxies and supermassive black holes (SMBH) in high redshift overdensities (protoclusters) by studying the star-forming galaxy and active galactic nucleus (AGN) population in the SSA22 protocluster. I examined possible environmental sources of the enhanced star formation and AGN activity in the z = 3.09 SSA22 protocluster using Hubble WFC3 ∼ 1.6 μm observations of the SSA22 field, including new observations centered on eight X-ray selected protocluster AGN. To investigate the role of mergers in the observed AGN and star formation enhancement, quantitative and visual morphological classifications were applied to F160W images of protocluster Lyman break galaxies (LBGs) in the fields of the AGN and z ∼ 3 field LBGs in SSA22 and the GOODS-N field. No significant differences are found between the morphologies and merger fractions of protocluster and field LBGs, though this conclusion is limited by small number statistics in the protocluster. The UV-to-near-IR spectral energy distributions (SED) of F160W-detected protocluster and field LBGs were fit to characterize their stellar masses and star formation histories (SFH). These fits suggest that the mean protocluster LBG is a factor of ∼ 2 times more massive and more attenuated than the mean z ∼ 3 field LBG. These results suggest that ongoing mergers are no more common among protocluster LBGs than field LBGs, though protocluster LBGs appear to be more massive. The larger mass of the protocluster LBGs may contribute to the enhancement of SMBH mass and accretion rate in the protocluster, in turn driving the protocluster AGN enhancement. I also analyzed the physical properties of 8 X-ray selected AGN and one candidate proto- quasar system (ADF22A1) in the SSA22 protocluster by fitting their X-ray-to-IR SEDs. SFHs were recovered for 7 of these systems which are well-fit by stellar population and AGN models. The majority of the protocluster AGN systems, including ADF22A1, are consistent with obscured SMBH growth in star forming galaxies. The SFRs, SMBH accretion rates, and masses estimated from the SED fits for the 9 protocluster AGN systems are consistent with the distributions of SFR, accretion rate, SMBH masses, and stellar masses for a sample of X-ray detected AGN candidates in the Chandra Deep Fields (CDF). The ratio between the sample-averaged SSA22 SMBH mass and CDF SMBH mass is constrained to \u3c 1.41. Furthermore, no statistically significant trends between the AGN or host galaxy properties and their location in the protocluster are found. The similarity of the protocluster and field AGN populations suggests that the observed protocluster AGN fraction enhancement may be driven by the SMBH mass distribution of the entire galaxy population, rather than only the AGN population, consistent with the interpretation of the results of the WFC3 F160W study of LBGs. The results presented here add to the existing body of knowledge on the growth of galaxies and SMBHs in protoclusters, suggesting that galaxies and their black holes grow by the same mechanisms in protoclusters and field environments, and that the observed AGN enhancement is driven instead by more frequent, secular, triggering of AGN episodes in star forming galaxies

Insights Into Star Formation and AGN Activity in Protocluster Environments From Morphological Studies and SED Fitting

In this dissertation I present work done from 2018-2023 to investigate the growth of galaxies and supermassive black holes (SMBH) in high redshift overdensities (protoclusters) by studying the star-forming galaxy and active galactic nucleus (AGN) population in the SSA22 protocluster. I examined possible environmental sources of the enhanced star formation and AGN activity in the z = 3.09 SSA22 protocluster using Hubble WFC3 ∼ 1.6 μm observations of the SSA22 field, including new observations centered on eight X-ray selected protocluster AGN. To investigate the role of mergers in the observed AGN and star formation enhancement, quantitative and visual morphological classifications were applied to F160W images of protocluster Lyman break galaxies (LBGs) in the fields of the AGN and z ∼ 3 field LBGs in SSA22 and the GOODS-N field. No significant differences are found between the morphologies and merger fractions of protocluster and field LBGs, though this conclusion is limited by small number statistics in the protocluster. The UV-to-near-IR spectral energy distributions (SED) of F160W-detected protocluster and field LBGs were fit to characterize their stellar masses and star formation histories (SFH). These fits suggest that the mean protocluster LBG is a factor of ∼ 2 times more massive and more attenuated than the mean z ∼ 3 field LBG. These results suggest that ongoing mergers are no more common among protocluster LBGs than field LBGs, though protocluster LBGs appear to be more massive. The larger mass of the protocluster LBGs may contribute to the enhancement of SMBH mass and accretion rate in the protocluster, in turn driving the protocluster AGN enhancement. I also analyzed the physical properties of 8 X-ray selected AGN and one candidate proto- quasar system (ADF22A1) in the SSA22 protocluster by fitting their X-ray-to-IR SEDs. SFHs were recovered for 7 of these systems which are well-fit by stellar population and AGN models. The majority of the protocluster AGN systems, including ADF22A1, are consistent with obscured SMBH growth in star forming galaxies. The SFRs, SMBH accretion rates, and masses estimated from the SED fits for the 9 protocluster AGN systems are consistent with the distributions of SFR, accretion rate, SMBH masses, and stellar masses for a sample of X-ray detected AGN candidates in the Chandra Deep Fields (CDF). The ratio between the sample-averaged SSA22 SMBH mass and CDF SMBH mass is constrained to \u3c 1.41. Furthermore, no statistically significant trends between the AGN or host galaxy properties and their location in the protocluster are found. The similarity of the protocluster and field AGN populations suggests that the observed protocluster AGN fraction enhancement may be driven by the SMBH mass distribution of the entire galaxy population, rather than only the AGN population, consistent with the interpretation of the results of the WFC3 F160W study of LBGs. The results presented here add to the existing body of knowledge on the growth of galaxies and SMBHs in protoclusters, suggesting that galaxies and their black holes grow by the same mechanisms in protoclusters and field environments, and that the observed AGN enhancement is driven instead by more frequent, secular, triggering of AGN episodes in star forming galaxies

Semiregular Polytopes and Amalgamated C-groups

In the classical setting, a convex polytope is said to be semiregular if its facets are regular and its symmetry group is transitive on vertices. This paper studies semiregular abstract polytopes, which have abstract regular facets, still with combinatorial automorphism group transitive on vertices. We analyze the structure of the automorphism group, focusing in particular on polytopes with two kinds of regular facets occurring in an "alternating" fashion. In particular we use group amalgamations to prove that given two compatible n-polytopes P and Q, there exists a universal abstract semiregular (n+1)-polytope which is obtained by "freely" assembling alternate copies of P and Q. We also employ modular reduction techniques to construct finite semiregular polytopes from reflection groups over finite fields.Comment: Advances in Mathematics (to appear, 28 pages

Freezing line of the Lennard-Jones fluid: a Phase Switch Monte Carlo study

We report a Phase Switch Monte Carlo (PSMC) method study of the freezing line of the Lennard-Jones (LJ) fluid. Our work generalizes to soft potentials the original application of the method to hard sphere freezing, and builds on a previous PSMC study of the LJ system by Errington (J. Chem. Phys. {\bf 120}, 3130 (2004)). The latter work is extended by tracing a large section of the Lennard-Jones freezing curve, the results for which we compare to a previous Gibbs-Duhem integration study. Additionally we provide new background regarding the statistical mechanical basis of the PSMC method and extensive implementation details.Comment: 18 pages, 6 figure

Gender and vocal production mode discrimination using the high frequencies for speech and singing

Humans routinely produce acoustical energy at frequencies above 6 kHz during vocalization, but this frequency range is often not represented in communication devices and speech perception research. Recent advancements toward high-definition (HD) voice and extended bandwidth hearing aids have increased the interest in the high frequencies. The potential perceptual information provided by high-frequency energy (HFE) is not well characterized. We found that humans can accomplish tasks of gender discrimination and vocal production mode discrimination (speech vs. singing) when presented with acoustic stimuli containing only HFE at both amplified and normal levels. Performance in these tasks was robust in the presence of low-frequency masking noise. No substantial learning effect was observed. Listeners also were able to identify the sung and spoken text (excerpts from “The Star-Spangled Banner”) with very few exposures. These results add to the increasing evidence that the high frequencies provide at least redundant information about the vocal signal, suggesting that its representation in communication devices (e.g., cell phones, hearing aids, and cochlear implants) and speech/voice synthesizers could improve these devices and benefit normal-hearing and hearing-impaired listeners

Regular Incidence Complexes, Polytopes, and C-Groups

Regular incidence complexes are combinatorial incidence structures generalizing regular convex polytopes, regular complex polytopes, various types of incidence geometries, and many other highly symmetric objects. The special case of abstract regular polytopes has been well-studied. The paper describes the combinatorial structure of a regular incidence complex in terms of a system of distinguished generating subgroups of its automorphism group or a flag-transitive subgroup. Then the groups admitting a flag-transitive action on an incidence complex are characterized as generalized string C-groups. Further, extensions of regular incidence complexes are studied, and certain incidence complexes particularly close to abstract polytopes, called abstract polytope complexes, are investigated.Comment: 24 pages; to appear in "Discrete Geometry and Symmetry", M. Conder, A. Deza, and A. Ivic Weiss (eds), Springe

Extravehicular activities limitations study. Volume 1: Physiological limitations to extravehicular activity in space

This report contains the results of a comprehensive literature search on physiological aspects of EVA. Specifically, the topics covered are: (1) Oxygen levels; (2) Optimum EVA work; (3) Food and Water; (4) Carbon dioxide levels; (5) Repetitive decompressions; (6) Thermal, and (7) Urine collection. The literature was assessed on each of these topics, followed by statements on conclusions and recommended future research needs

Wind Climatology at 87 km above the Rocky Mountains at Bear Lake Observatory--Fabry-Perot Observations of OH

This paper presents the neutral -wind climatology at approximately 87-km 53 altitude from Utah State University\u27s Bear Lake Observatory (BLO). a mid-latitude site 54 situated in the middle of the Rocky Mountains. The winds were determined using a very 55 sensitive Fabry-Perot interferometer (FPI) observing the OH Me inel (6-2) PI (3) line al 56 843 nm. The climatology. determined from monthly averages of the nightly evolution of 57 the geographic meridional and zonal wind components over forty· five months, has three 58 distinct seasonal patterns: winter (November- February), summer (May-Jul y), and late 59 Slimmer (August and September). The background zonal wind is eastward the whole year 60 except March and April. The background meridional wind is northward in winter and 61 southward during the rest of the year. In late summer. the winds exhibit a very strong 62 semidiurnal tidal variation almost every night. In summer, they exhibit a similar tidal 63 variation on enough nights that a semi diurnal pattern appears in the climatology. In 64 winter. the nighHo·night variability is so great that little structure is evident in the 65 climatology . These winds are compared to those from other techniques or sites: ~l 66 observations from UARS. FPI observations from Michigan, and MF radar observations. 67 While generally agreeing in relative amplitudes and i.n phase. differences do exist. 68 especially the weak semidiurnal tide at BLO in winter and a greatly reduced {tide at spring 69 equinox compared to late summer. It is likely that these differences arise from the 2 70 topographical generation of gravity waves by winds flowing over the Rocky Mountains. 71 The tidal variations are also compared to results from the global-scale wave model 72 (GSWM): our semidiurnal amplitudes arc considerably bigger except in winter, and our 73 phases vary from showing very good agreement in July, fair agreement in April and 74 January, and disagreement in October. These large differences may be evidence that 11011 - 75 linear effects are more important than realized. The behavior of the background winds is 76 consistent with different populations of gravity waves reaching 87 km in summer and 77 winter. The behavior of the semidiurnal tidal variation is consistent\u27 with a strong 78 interaction between the tidal and gravity·wave wind fields, and is consistent with the 79 different summer and Winter gravity wave population s, and with a fall· spring asymmetry 80 characterized by much weaker gravity wave sources in late summer than near spring 81 equinox