Author: j5rson

Kate Storey-Fisher, David W. Hogg, Hans-Walter Rix, Anna-Christina Eilers, Giulio Fabbian, Michael Blanton, David Alonso

We present a new, all-sky quasar catalog, Quaia, that samples the largest comoving volume and has the cleanest selection function of any existing spectroscopic quasar sample. The catalog draws on the 6,649,162 quasar candidates identified by the Gaia mission that have redshift estimates from the space observatory’s low-resolution BP/RP spectra. This initial sample is highly homogeneous and complete, but has low purity, and 18% of even the bright (G<20.0) confirmed quasars have discrepant redshift estimates (|Δz/(1+z)|>0.2) compared to those from the Sloan Digital Sky Survey (SDSS). In this work, we combine the Gaia candidates with unWISE infrared data (based on the Wide-field Infrared Survey Explorer survey) to construct a catalog useful for cosmological and astrophysical quasar studies. We apply cuts based on proper motions and Gaia and unWISE colors, reducing the number of contaminants by ∼4×. We improve the redshifts by training a k-nearest neighbors model on colors and Gaia redshift estimates and using SDSS redshift labels, and achieve redshift estimates on the G<20.0 sample with only 6% (10%) catastrophic errors with |Δz/(1+z)|>0.2 (0.1), a reduction of ∼3× (∼2×) compared to the Gaia redshifts. The final catalog has 1,295,502 quasars with a G<20.5, and 755,850 candidates in an even cleaner G<20.0 sample. We also construct a rigorous all-sky selection function model for the catalog. We compare Quaia to existing quasar catalogs, in particular showing that its large effective volume makes it a highly competitive sample for cosmological large-scale structure analyses. The catalog is publicly available at this https URL.

Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

https://arxiv.org/abs/2306.17749

Christopher Usher, Kristen C. Dage, Léo Girardi, Pauline Barmby, Charles J. Bonatto, Ana L. Chies-Santos, William I. Clarkson, Matias Gómez Camus, Eduardo A. Hartmann, Annette M. N. Ferguson, Adriano Pieres, Loredana Prisinzano, Katherine L.Rhode, R. Michael Rich, Vincenzo Ripepi, Basilio Santiago, Keivan G. Stassun, R.A. Street, Róbert Szabó, Laura Venuti, Simone Zaggia, Marco Canossa, Pedro Floriano, Pedro Lopes, Nicole L. Miranda, Raphael A. P. Oliveira, Marta Reina-Campos, A. Roman-Lopes, Jennifer Sobeck

The Vera C. Rubin Observatory will undertake the Legacy Survey of Space and Time, providing an unprecedented, volume-limited catalog of star clusters in the Southern Sky, including Galactic and extragalactic star clusters. The Star Clusters subgroup of the Stars, Milky Way and Local Volume Working Group has identified key areas where Rubin Observatory will enable significant progress in star cluster research. This roadmap represents our science cases and preparation for studies of all kinds of star clusters from the Milky Way out to distances of tens of megaparsecs.

Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

https://arxiv.org/abs/2306.17333

Olga Borodina, Thomas G. Williams, Mattia C. Sormani, Sharon Meidt, Eva Schinnerer

Pattern speeds are a fundamental parameter of the dynamical features (e.g. bars, spiral arms) of a galaxy, setting resonance locations. Pattern speeds are not directly observable, so the Tremaine-Weinberg (TW) method has become the most common method used to measure them in galaxies. However, it has not been tested properly whether this method can straightforwardly be applied to gas tracers, despite this being widely done in the literature. When applied to observations, the TW method may return invalid results, which are difficult to diagnose due to a lack of ground truth for comparison. Although some works applying the TW method to simulated galaxies exist, only stellar populations have been tested. Therefore, here we explore the applicability of the TW method for gas gracers, by applying it to hydrodynamical simulations of galaxies, where we know the true value of the bar pattern speed. We perform some simple tests to see if the TW method has a physically reasonable output. We add different kinds of uncertainties (e.g. in position angle or flux) to the data to mock observational errors based on the magnitude of uncertainty present in the observations. Second, we test the method on 3D simulations with chemical networks. We show that in general, applying TW to observations of gas will not recover the true pattern speed. These results have implications for many “pattern speeds” reported in the literature, and based on these tests we also give some best practices for measuring pattern speeds using gas tracers going forwards.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2306.17780

Tadeus Carl, Eva Wirström, Per Bergman, Steven Charnley, Yo-Ling Chuang, Yi-Jehng Kuan

One of the most fundamental hypotheses in astrochemistry and astrobiology states that crucial biotic molecules like glycine (NH2CH2COOH) found in meteorites and comets are inherited from early phases of star formation. Most observational searches for glycine in the interstellar medium have focused on warm, high-mass molecular cloud sources. However, recent studies suggest that it might be appropriate to shift the observational focus to cold, low-mass sources. We aim to detect glycine towards the so-called methanol hotspot in the Barnard 5 dark cloud. The hotspot is a cold source (Tgas≈7.5 K) with yet high abundances of complex organic molecules (COMs) and water in the gas phase. We carried out deep, pointed observations with the Onsala 20m telescope, targeting several transitions of glycine conformers I and II (Gly-I and Gly-II) in the frequency range 70.2-77.9 GHz. No glycine lines are detected towards the targeted position, but we use a line stacking procedure to derive sensitive abundance upper limits w.r.t. H2 for Gly-I and Gly-II, i.e. ≤(2-5)×10−10 and ≤(0.7-3)×10−11, respectively. The obtained Gly-II upper limits are the most stringent for a cold source, while the Gly-I upper limits are mostly on the same order as previously measured limits. The measured abundances w.r.t. H2 of other COMs at the B5 methanol hotspot range from 2×10−10 (acetaldehyde) to 2×10−8 (methanol). Hence, based on a total glycine upper limit of (2-5)×10−10, we cannot rule out that glycine is present but undetected.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2306.17713

Marta Reina-Campos, Alison Sills, Godefroy Bichon

Massive star clusters are often used as tracers of galaxy formation and assembly. In order to do so, we must understand their properties at formation, and how those properties change with time, galactic environment, and galaxy assembly history. The two most important intrinsic properties that govern star cluster evolution are mass and radius. In this paper, we investigate 10 theoretically and observationally motivated initial size-mass relations for star clusters, and evolve populations of clusters through galaxy formation models. We compare our results to each other and to observations of cluster populations in M83, M31, and the Milky Way. We find that none of our size-mass relations agree with the observations after 6-10 Gyr of evolution. We can successfully reproduce the cluster mass functions with models that have a small range of initial radii, and which do not allow cluster radii to change with time. However, these models do not agree with our understanding of cluster evolution, which does involve radius evolution, and do not match the observed distributions of radii. We note that there is a region of parameter space where clusters are optimally protected from both tidal shocks and evaporation due to two-body relaxation. Clusters which are allowed to evolve into this parameter space will likely survive. An improved understanding of both mass and radius evolution of star clusters in realistic, time-varying galactic potentials is necessary to appropriately make the connection between present-day cluster properties and their use as tracers of galaxy formation and assembly.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2306.17701

The COVID-19 affected communities and the economy beyond public health. The epidemic is expected to increase global poverty and inequality, making it crucial to study its effects. Several international organisations determined that a “new recession” was underway due to the global pandemic’s destructive effects on the financial, social, and personal spheres. Despite their best efforts, many undeveloped nations are fighting the pandemic’s aftereffects. Bangladesh is like other nations. Global economic and social changes will lead to new difficulties in the near future. Thus, studying COVID’s effects from a variety of perspectives, including gender, is crucial and timely. This paper explores the aftermath of the epidemic, focusing on the plight of women workers. In doing so, it sheds light on a particularly marginalised group, including maids and housekeepers, who have been denied benefits and recognition for their job.

Sarker, A. (2022, December 19). COVID-19 and socioeconomic context in Bangladesh: Discussion from a gendered point of view. https://doi.org/10.5281/zenodo.7455575

The evolution of the Universe is observable when the expansive motion already exists; thus, the definition of universal states (before the beginning and after the end of the expansion) with zero kinetic energy can be a challenge to be solved by parallel analysis. Considering that a complete description of the Universe can provide important insights, the logic of conceptual connections is used as an alternative; in this sense, an exclusive presence of linear Space (1D) in momentary states of maximum contraction and expansion is analyzed, with our Universe (3D Space) considered as created and existing between these extremes. The concept of rest mass energy became applicable, revealing that the complete evolution of the Universe is spatially dynamic in a permanent time dimension, allowing for the relative maintenance of any existence.

Petrakis, S. G. (2023, May 9). Continuous Existence, Universe: the dynamics resulting from its maximum states of contraction and expansion (Cosmology from Vanishing Dimensions). https://doi.org/10.31219/osf.io/czemg

The COVID-19 pandemic had a profound impact on business leadership, specifically on chief executive officers (CEOs). To document the psychological impacts of the pandemic on corporate leadership, this study analyzed the language of CEOs during company quarterly earnings calls (N = 19,536) one year before and after the onset of the pandemic. Following the start of lockdowns, CEOs exhibited significant language shifts. Analytic thinking declined, and their language became less technical and more personal and intuitive. CEOs also showed signs of increased cognitive load as they grappled with the pandemic’s impact on their business practices. The study observed a substantial decrease in collective-focused language (we-usage) among CEOs, indicative of disconnection from their companies. Concurrently, there was an increase in self-focused (I-usage) language, suggesting heightened preoccupation among business leaders. The observed language changes reflect the unique effect of the pandemic on CEOs, which had some notable differences compared to the general population. This study sheds light on how the COVID-19 pandemic influenced business leaders’ psychological states and decision-making strategies—processes that have a substantial impact on a company’s performance. The findings underscore the importance of language data in understanding large-scale societal events

Mesquiti, S., & Seraj, S. (2022, November 16). The Psychological Impacts of the COVID-19 Pandemic on Business Leadership. https://doi.org/10.31234/osf.io/kvar9

This paper introduces an advanced method that integrates contingent valuation and machine learning (CVML) to estimate residents’ demand for mitigating environmental pollutions and climate change. To be precise, CVML is an innovative hybrid machine-learning model, and it can leverage a limited amount of survey data for prediction and data enrichment purposes. The model comprises of two interconnected modules: Module I, an unsupervised learning algorithm, and Module II, a supervised learning algorithm. Module I is responsible for clustering the data (x^sur) into groups based on common characteristics, thereby grouping the corresponding dependent variable (y^sur) values as well. Take a survey on the topic of air pollution in Hanoi in 2019 as an example, we find that CVML can predict households’ willingness– to– pay for polluted air mitigation at a high degree of accuracy (i.e., over 90%). This finding suggests that CVML is a powerful and practical method that would be potentially widely applied in fields of environmental economics and sustainability science in years to come.

Khuc, V., & Tran, D. (2023, May 18). Contingent valuation machine learning (CVML): A novel method for estimating citizens’ willingness- to- pay for safer and cleaner environment. https://doi.org/10.31219/osf.io/r35bz

Mental health problems often co-occur, as do physical conditions. There is also comorbidity between mental and physical health problems, such as cancer and depression. In their recent work, Brandt et al. (2023) propose that the d(isease) factor explains why. They define the d factor as an “underlying disease dimension […] that accounts for the individuals’ propensity to develop mental as well as physical conditions”, and as “a general vulnerability to develop any of the included conditions”. This rests on similar work in the mental health literature, where some have claimed to have identified a p(sychopathology) factor to explain the comorbidity among mental health problems (Caspi & Moffitt, 2018). Brandt et al. (2023) conclude that “our results support the assumption of the existence of a general d factor in adults”, and that this has important implications for both “conceptualization and classification of mental and physical conditions” as well as “clinical practice and policy”. I explain in this brief piece why these conclusions do not follow.

Fried, E. I. (2023, July 9). No evidence for the existence of the d (isease) factor. Retrieved from psyarxiv.com/47avw