A new HDF5 based raw data model for CCAT

CCAT will be a large sub-millimeter telescope to be built near the ALMA site in northern Chile. The telescope must support a varied set of instrumentation including large format KID cameras, a large heterodyne array and a KID-based direct detection multi-object spectrometer. We are developing a new raw data model based on HDF5 that can cope with the expected data rates of order Gbit/s and is flexible enough to hold raw data from all planned instruments.Comment: Submitted to Proceedings of ADASS XXI

An overview of the planned CCAT software system

CCAT will be a 25m diameter sub-millimeter telescope capable of operating in the 0.2 to 2.1mm wavelength range. It will be located at an altitude of 5600m on Cerro Chajnantor in northern Chile near the ALMA site. The anticipated first generation instruments include large format (60,000 pixel) kinetic inductance detector (KID) cameras, a large format heterodyne array and a direct detection multi-object spectrometer. The paper describes the architecture of the CCAT software and the development strategy.Comment: 17 pages, 6 figures, to appear in Software and Cyberinfrastructure for Astronomy III, Chiozzi & Radziwill (eds), Proc. SPIE 9152, paper ID 9152-10

The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background

El conjunto de datos de 15 años de NANOGrav muestra evidencias de la presencia de un fondo de ondas gravitacionales (GWB) de baja frecuencia. Aunque muchos procesos físicos pueden originar estas ondas gravitacionales de baja frecuencia, aquí analizamos la señal como procedente de una población de agujeros negros binarios supermasivos (SMBH) distribuidos por todo el Universo. Demostramos que los modelos astrofísicos de poblaciones binarias SMBH son capaces de reproducir tanto la amplitud como la forma del espectro de ondas gravitacionales de baja frecuencia observado. Aunque múltiples variaciones del modelo son capaces de reproducir el espectro GWB con nuestra precisión de medida actual, nuestros resultados subrayan la importancia de modelar con precisión la evolución binaria para producir espectros GWB realistas. Además, aunque unos parámetros razonables son capaces de reproducir las observaciones de 15 años, la amplitud implícita del GWB requiere que un gran número de parámetros se sitúen en los límites de los valores esperados o que un pequeño número de parámetros difieran notablemente de las expectativas estándar. Aunque todavía no somos capaces de establecer definitivamente el origen de la señal GWB inferida, la consistencia de la señal con las expectativas astrofísicas ofrece una perspectiva tentadora para confirmar que las binarias SMBH son capaces de formarse, alcanzar separaciones de sub-segundos y finalmente unirse. A medida que la importancia aumente con el tiempo, las características de orden superior del espectro del GWB determinarán definitivamente la naturaleza del GWB y permitirán nuevas restricciones sobre las poblaciones de SMBH. © 2023The NANOGrav 15 yr data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations. © 2023. The Author(s). Published by the American Astronomical Society

Concussion-Associated Gene Variant COMT rs4680 Is Associated With Elite Rugby Athlete Status

Objective: Concussions are common match injuries in elite rugby, and reports exist of reduced cognitive function and long-term health consequences that can interrupt or end a playing career and produce continued ill health. The aim of this study was to investigate the association between elite rugby status and 8 concussion-associated risk polymorphisms. We hypothesized that concussion-associated risk genotypes and alleles would be underrepresented in elite rugby athletes compared with nonathletes. Design: A case-control genetic association study.Setting:  Institutional (university). Participants: Elite White male rugby athletes [n = 668, mean (SD) height 1.85 (0.07) m, mass 102 (12) kg, and age 29 (7) years] and 1015 nonathlete White men and women (48% men). Interventions: Genotype was the independent variable, obtained by PCR of genomic DNA using TaqMan probes.Main Outcome Measure:  Elite athlete status with groups compared using χ2 and odds ratio (OR). Results: The COMT rs4680 Met/Met (AA) genotype, Met allele possession, and Met allele frequency were lower in rugby athletes (24.8%, 74.6%, and 49.7%, respectively) than nonathletes (30.2%, 77.6%, and 54.0%; P < 0.05). The Val/Val (GG) genotype was more common in elite rugby athletes than nonathletes (OR 1.39, 95% confidence interval 1.04-1.86). No other polymorphism was associated with elite athlete status. Conclusions: Elite rugby athlete status is associated with COMT rs4680 genotype that, acting pleiotropically, could affect stress resilience and behavioral traits during competition, concussion risk, and/or recovery from concussion. Consequently, assessing COMT rs4680 genotype might aid future individualized management of concussion risk among athletes.

Concussion-Associated Polygenic Profiles of Elite Male Rugby Athletes

Due to the high-velocity collision-based nature of elite rugby league and union, the risk of sustaining a concussion is high. Occurrence of and outcomes following a concussion are probably affected by the interaction of multiple genes in a polygenic manner. This study investigated whether suspected concussion-associated polygenic profiles of elite rugby athletes differed from non-athletes and between rugby union forwards and backs. We hypothesised that a total genotype score (TGS) using eight concussion-associated polymorphisms would be higher in elite rugby athletes than non-athletes, indicating selection for protection against incurring or suffering prolonged effects of, concussion in the relatively high-risk environment of competitive rugby. In addition, multifactor dimensionality reduction was used to identify genetic interactions. Contrary to our hypothesis, TGS did not differ between elite rugby athletes and non-athletes (p ≥ 0.065), nor between rugby union forwards and backs (p = 0.668). Accordingly, the TGS could not discriminate between elite rugby athletes and non-athletes (AUC ~0.5), suggesting that, for the eight polymorphisms investigated, elite rugby athletes do not have a more ‘preferable’ concussion-associated polygenic profile than non-athletes. However, the COMT (rs4680) and MAPT (rs10445337) GC allele combination was more common in rugby athletes (31.7%; p < 0.001) and rugby union athletes (31.8%; p < 0.001) than non-athletes (24.5%). Our results thus suggest a genetic interaction between COMT (rs4680) and MAPT (rs10445337) assists rugby athletes in achieving elite status. These findings need exploration vis-à-vis sport-related concussion injury data and could have implications for the management of inter-individual differences in concussion risk

Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set

When galaxies merge, the supermassive black holes in their centers may form binaries and, during the process of merger, emit low-frequency gravitational radiation in the process. In this paper we consider the galaxy 3C66B, which was used as the target of the first multi-messenger search for gravitational waves. Due to the observed periodicities present in the photometric and astrometric data of the source of the source, it has been theorized to contain a supermassive black hole binary. Its apparent 1.05-year orbital period would place the gravitational wave emission directly in the pulsar timing band. Since the first pulsar timing array study of 3C66B, revised models of the source have been published, and timing array sensitivities and techniques have improved dramatically. With these advances, we further constrain the chirp mass of the potential supermassive black hole binary in 3C66B to less than $(1.65\pm0.02) \times 10^9~{M_\odot}$ using data from the NANOGrav 11-year data set. This upper limit provides a factor of 1.6 improvement over previous limits, and a factor of 4.3 over the first search done. Nevertheless, the most recent orbital model for the source is still consistent with our limit from pulsar timing array data. In addition, we are able to quantify the improvement made by the inclusion of source properties gleaned from electromagnetic data to `blind' pulsar timing array searches. With these methods, it is apparent that it is not necessary to obtain exact a priori knowledge of the period of a binary to gain meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap