Exploring Low Cost Non-Contact Detection of Biosignals for HCI

In an effort to make biosignal integration more accessible to explore for more HCI researchers, this paper presents our investigation of how well a standard, near ubiquitous webcam can support remote sensing of heart rate and respiration rate across skin tone ranges. The work contributes: how the webcam can be used for this purpose, its limitations, and how to mitigate these limitations affordably, including how the skin tone range affect the estimation results.Comment: 10 pages, 5 figure

COMTILES: A CASE STUDY OF A CLOUD OPTIMIZED TILE ARCHIVE FORMAT FOR DEPLOYING PLANET-SCALE TILSETS IN THE CLOUD

The container formats commonly used for managing map tiles, such as MBTiles and GeoPackage, were originally designed with only POSIX filesystem access in mind. This makes these file formats inefficient to use in a cloud native environment, especially in combination with large tilesets. The Cloud Optimized GeoTIFF format solves the problem of providing large satellite data in the cloud, creating a new category of so-called cloud optimized data formats. This type of format allows geospatial data to be deployed as a single file on a cheap and scalable cloud object storage such as AWS S3 and accessed directly from a browser without the need for a dedicated backend. Based on the concepts of the COG format, this contribution proposes a new cloud optimized file format called COMTiles, specially designed for planet-scale tilesets. This format has the potential to simplify the deployment workflow of large tilesets in a cloud-native environment, while simultaneously reducing the hosting costs. In comparison to PMTiles, another cloud-optimized tile archive solution, COMTiles can reduce the number of transferred data and the performance of decoding portions of the file. COMTiles also adds support for different coordinate systems

Can Cosmological Simulations Reproduce the Spectroscopically Confirmed Galaxies Seen at z≥10z\geq 10?

Recent photometric detections of extreme $(z>10)$ redshift galaxies from the JWST have been shown to be in strong tension with existing simulation models for galaxy formation, and in the most acute case, in tension with $\Lambda CDM$ itself. These results, however, all rest on the confirmation of these distances by spectroscopy. Recently, the JADES survey has detected the most distant galaxies with spectroscopically confirmed redshifts, with four galaxies found with redshifts between $z=10.38$ and $z=13.2$. In this paper, we compare simulation predictions from four large cosmological volumes and two zoom-in protoclusters with the JADES observations to determine whether these spectroscopically confirmed galaxy detections are in tension with existing models for galaxy formation, or with $\Lambda CDM$ more broadly. We find that existing models for cosmological galaxy formation can generally reproduce the observations for JADES, in terms of galaxy stellar masses, star formation rates, and the number density of galaxies at $z>10$.Comment: ApJL submitted, comments welcom

Modeling the Redshift Evolution of the Normal Galaxy X-ray Luminosity Function

Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high redshift galaxies allow us to probe the formation and evolution of X-ray binaries on very long timescales. In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z = 0 to 20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. (2011) to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy. We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low CE efficiencies, a 50% twins mass ratio distribution, a steeper IMF exponent, and high stellar wind mass loss rates best match observational results from Tzanavaris & Georgantopoulos (2008), though they significantly underproduce bright early-type and very bright (Lx > 10d41) late-type galaxies. These discrepancies are likely caused by uncertainties in hot gas emission and SFHs, AGN contamination, and a lack of dynamically formed Low-mass XRBs. In our highest likelihood models, we find that hot gas emission dominates the emission for most bright galaxies. We also find that the evolution of the normal galaxy X-ray luminosity density out to z = 4 is driven largely by XRBs in galaxies with X-ray luminosities between 10d40 and 10d41 erg/s.Comment: Accepted into ApJ, 17 pages, 3 tables, 7 figures. Text updated to address referee's comment

A rumble in the dark: signatures of self-interacting dark matter in supermassive black hole dynamics and galaxy density profiles

We explore for the first time the effect of self-interacting dark matter (SIDM) on the dark matter (DM) and baryonic distribution in massive galaxies formed in hydrodynamical cosmological simulations, including explicit baryonic physics treatment. A novel implementation of supermassive black hole (SMBH) formation and evolution is used, as in Tremmel et al., allowing us to explicitly follow the SMBH dynamics at the centre of galaxies. A high SIDM constant cross-section is chosen, σ = 10 cm2gr−1, to amplify differences from CDM models. Milky Way-like galaxies form a shallower DM density profile in SIDM than they do in cold dark matter (CDM), with differences already at 20 kpc scales. This demonstrates that even for the most massive spirals, the effect of SIDM dominates over the adiabatic contraction due to baryons. Strikingly, the dynamics of SMBHs differs in the SIDM and reference CDM case. SMBHs in massive spirals have sunk to the centre of their host galaxy in both the SIDM and CDM run, while in less massive galaxies about 80 per cent of the SMBH population is off-centred in the SIDM case, as opposed to the CDM case in which ∼ 90 per cent of SMBHs have reached their host’s centre. SMBHs are found as far as ∼9 kpc away from the centre of their host SIDM galaxy. This difference is due to the increased dynamical friction time-scale caused by the lower DM density in SIDM galaxies compared to CDM, resulting in core stalling. This pilot work highlights the importance of simulating in a full hydrodynamical context different DM models combined to the SMBH physics to study their influence on galaxy formation

Not So Heavy Metals: Black Hole Feedback Enriches the Circumgalactic Medium

We examine the effects of supermassive black hole (SMBH) feedback on the circumgalactic medium (CGM) using a cosmological hydrodynamic simulation (Romulus25) and a set of four zoom-in "genetically modified" Milky-Way–mass galaxies sampling different evolutionary paths. By tracing the distribution of metals in the CGM, we show that O vi is a sensitive indicator of SMBH feedback. First, we calculate the column densities of O vi in simulated Milky-Way–mass galaxies and compare them with observations from the COS-Halos Survey. Our simulations show column densities of O vi in the CGM consistent with those of COS-Halos star-forming and quenched galaxies. These results contrast with those from previous simulation studies which typically underproduce CGM column densities of O vi. We determine that a galaxy's star formation history and assembly record have little effect on the amount of O vi in its CGM. Instead, column densities of O vi are closely tied to galaxy halo mass and BH growth history. The set of zoom-in, genetically modified Milky-Way–mass galaxies indicates that the SMBH drives highly metal-enriched material out into its host galaxy's halo, which in turn elevates the column densities of O vi in the CGM