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

Randomized controlled trial of patient-controlled sedation for colonoscopy: Entonox vs modified patient-maintained target-controlled propofol

Aim Propofol sedation is often associated with deep sedation and decreased manoeuvrability. Patient-maintained sedation has been used in such patients with minimal side-effects. We aimed to compare novel modified patient-maintained target-controlled infusion (TCI) of propofol with patient-controlled Entonox inhalation for colonoscopy in terms of analgesic efficacy (primary outcome), depth of sedation, manoeuvrability and patient and endoscopist satisfaction (secondary outcomes). Method One hundred patients undergoing elective colonoscopy were randomized to receive either TCI propofol or Entonox. Patients in the propofol group were administered propofol initially to achieve a target concentration of 1.2 μ g/ml and then allowed to self-administer a bolus of propofol (200 μ g/kg/ml) using a patient-controlled analgesia pump with a handset. Entonox group patients inhaled the gas through a mouthpiece until caecum was reached and then as required. Sedation was initially given by an anaesthetist to achieve a score of 4 (Modified Observer's Assessment of Alertness and Sedation Scale), and colonoscopy was then started. Patients completed an anxiety score (Hospital Anxiety and Depression questionnaire), a baseline letter cancellation test and a pain score on a 100-mm visual analogue scale before and after the procedure. All patients completed a satisfaction survey at discharge and 24 h postprocedure. Results The median dose of propofol was 174 mg, and the median number of propofol boluses was four. There was no difference between the two groups in terms of pain recorded (95% confidence interval of the difference -0.809, 5.02) and patient/endoscopist satisfaction. There was no difference between the two groups in either depth of sedation or manoeuvrability. Conclusion Both Entonox and the modified TCI propofol provide equally effective sedation and pain relief, simultaneously allowing patients to be easily manoeuvred during the procedures. © 2010 The Authors. Colorectal Disease © 2010 The Association of Coloproctology of Great Britain and Ireland

Phase coexistence of cluster crystals: beyond the Gibbs phase rule

We report a study of the phase behavior of multiple-occupancy crystals through simulation. We argue that in order to reproduce the equilibrium behavior of such crystals it is essential to treat the number of lattice sites as a constraining thermodynamic variable. The resulting free-energy calculations thus differ considerably from schemes used for single-occupancy lattices. Using our approach, we obtain the phase diagram and the bulk modulus for a generalized exponential model that forms cluster crystals at high densities. We compare the simulation results with existing theoretical predictions. We also identify two types of density fluctuations that can lead to two sound modes and evaluate the corresponding elastic constants.Comment: 4 pages, 3 figure