Author: j5rson

Beomdu Lim, Jongsuk Hong, Jinhee Lee, Hyeong-Sik Yun, Narae Hwang, Byeong-Gon Park

The star-forming region W5 is a major part of the Cassiopeia OB6 association. Its internal structure and kinematics may provide hints of the star formation process in this region. Here, we present a kinematic study of young stars in W5 using the Gaia data and our radial velocity data. A total 490 out of 2,000 young stars are confirmed as members. Their spatial distribution shows that W5 is highly substructured. We identify a total of eight groups using the k-means clustering algorithm. There are three dense groups in the cavities of H II bubbles, and the other five sparse groups are distributed at the ridge of the bubbles. The three dense groups have almost the same ages (5 Myr) and show a pattern of expansion. The scale of their expansion is not large enough to account for the overall structure of W5. The three northern groups are, in fact, 3 Myr younger than the dense groups, which indicates the independent star formation events. Only one group of them shows the signature of feedback-driven star formation as its members move away from the eastern dense group. The other two groups might have formed in a spontaneous way. On the other hand, the properties of two southern groups are not understood as those of a coeval population. Their origins can be explained by dynamical ejection of stars and multiple star formation. Our results suggest that the substructures in W5 formed through multiple star-forming events in a giant molecular cloud.

Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

https://arxiv.org/abs/2307.06557

So-Myoung Park, Kyungwon Chun, Jihye Shin, Hyunjin Jeong, Joon Hyeop Lee, Mina Pak, Rory Smith, Jae-Woo Kim

We investigate the fraction of quenched satellite galaxies in host galaxy groups and clusters using TNG300 in the IllustrisTNG cosmological magnetohydrodynamical simulations. Simulations show that most satellites are quenched after they fall into their final hosts: post-processing is a more dominant mechanism of galaxy quenching than pre-processing. We find the fraction of quenched satellites at z=0 increases with host mass, which implies that more massive hosts have higher quenching efficiency because more massive hosts have more massive groups infalling. Furthermore, we find that hosts that have many early-infall satellites show a higher fraction of quenched satellites at z=0 than those having many late-infall satellites, which results in a scatter of the quenched fraction of satellites in a given mass range of hosts at z=0. Our results highlight the significance of the mass of hosts and the different infall times of satellites in understanding galaxy quenching.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2307.05682

Seoyoung Lyla Jung, N. M. McClure-Griffiths, Ruediger Pakmor, Yik Ki Ma, Alex S. Hill, Cameron L. Van Eck, Craig S. Anderson

Faraday rotation measure (RM) is arguably the most practical observational tracer of magnetic fields in the diffuse circumgalactic medium (CGM). We sample synthetic Faraday rotation skies of Milky Way-like galaxies in IllustrisTNG50 by placing an observer inside the galaxies at a solar circle-like position. Our synthetic RM grids emulate specifications of current and upcoming surveys; the NRAO VLA Sky Survey (NVSS), the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM), and a future Square Kilometre Array (SKA1-mid) polarisation survey. It has been suggested that magnetic fields regulate the survival of high-velocity clouds. However, there is only a small number of observational detections of magnetised clouds thus far. In the first part of the paper, we test conditions for the detection of magnetised circumgalactic clouds. Based on the synthetic RM samplings of clouds in the simulations, we predict upcoming polarimetric surveys will open new opportunities for the detection of even low-mass and distant clouds. In the second part of the paper, we investigate the imprint of the CGM in the all-sky RM distribution. We test whether the RM variation produced by the CGM is correlated with global galaxy properties, such as distance to a satellite, specific star formation rate, neutral hydrogen covering fraction, and accretion rate to the supermassive black hole. We argue that the observed fluctuation in the RM measurements, which has been considered an indication of intergalactic magnetic fields, might in fact incorporate a significant contribution of the Milky Way CGM.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2307.05808

Quentin Salomé, Yair Krongold, Anna Lia Longinotti, Manuela Bischetti, Santiago García-Burillo, Olga Vega, Miguel Sánchez-Portal, Chiara Feruglio, María Jesús Jiménez-Donaire, Maria Vittoria Zanchettin

We present the first systematic study of the molecular gas and star formation efficiency in a sample of ten narrow-line Seyfert 1 galaxies selected to have X-ray Ultra Fast Outflows and, therefore, to potentially show AGN feedback effects. CO observations were obtained with the IRAM 30m telescope in six galaxies and from the literature for four galaxies. We derived the stellar mass, star formation rate, AGN and FIR dust luminosities by fitting the multi-band spectral energy distributions with the CIGALE code. Most of the galaxies in our sample lie above the main sequence (MS) and the molecular depletion time is one to two orders of magnitude shorter than the one typically measured in local star-forming galaxies. Moreover, we found a promising correlation between the star formation efficiency and the Eddington ratio, as well as a tentative correlation with the AGN luminosity. The role played by the AGN activity in the regulation of star formation within the host galaxies of our sample remains uncertain (little or no effect? positive feedback?). Nevertheless, we can conclude that quenching by the AGN activity is minor and that star formation will likely stop in a short time due to gas exhaustion by the current starburst episode.

Astrophysics of Galaxies (astro-ph.GA)

https://arxiv.org/abs/2307.06087

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