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DOE OSTI2025

Interacting dark sector within ETHOS: Cosmological constraints from SPT cluster abundance with DES and HST weak lensing data

We use galaxy cluster abundance measurements from the South Pole Telescope enhanced by multicomponent matched filter confirmation and complemented with mass information obtained using weak-lensing data from Dark Energy Survey Year 3 (DES Y3) and targeted Hubble Space Telescope observations for probing deviations from the cold dark matter paradigm. Concretely, we consider a class of dark sector models featuring interactions between dark matter (DM) and a dark radiation (DR) component within the framework of the effective theory of structure formation (ETHOS). We focus on scenarios that lead to power suppression over a wide range of scales, and thus can be tested with data sensitive to large scales, as realized, for example, for DM–DR interactions following from an unbroken non-Abelian 𝑆⁢𝑈⁡(𝑁) gauge theory (interaction rate with power-law index 𝑛 = 0 within the ETHOS parametrization). Cluster abundance measurements are mostly sensitive to the amount of DR interacting with DM, parametrized by the ratio of DR temperature to the cosmic microwave background (CMB) temperature, 𝜉 DR = 𝑇 DR /𝑇 CMB . We find an upper limit 𝜉 DR < 17% at 95% credibility. When the cluster data are combined with Planck 2018 CMB data along with baryon acoustic oscillation (BAO) measurements we find 𝜉 DR < 10%, corresponding to a limit on the abundance of interacting DR that is around 3 times tighter than that from CMB + BAO data alone. We also discuss the complementarity of weak lensing informed cluster abundance studies with probes sensitive to smaller scales, explore the impact on our analysis of massive neutrinos, and comment on a slight preference for the presence of a nonzero interacting DR abundance, which enables a physical solution to the 𝑆 8 tension.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2000

The Heavy Element Abundance in Groups of Galaxies

Over the past few years we have analyzed a sample of clusters observed by the Advanced Spacecraft for Cosmology Astrophysics (ASCA) X-ray satellite. We performed spatially resolved X-ray spectroscopy of a sample of 18 relaxed clusters of galaxies with gas temperatures below 4 keV. The spectral analysis was done using ASCA/SIS (Solid state Imaging Spectrometer) data combined with imaging data from ROSAT/PSPC (German acronym for X-ray satellite/Position Sensitive Proportional Counter) and Einstein/IPC (Imaging Proportional Counter) observations. We derived temperature profiles using single-temperature fits for all of the clusters in the sample, and also corrected for the presence of cold gas in the center of so-called 'cooling flow' clusters. For all of the clusters in the sample we derived Si and Fe abundance profiles. For a few of the clusters we also were able to derive Ne and S abundance profiles. We compared the elemental abundances derived at similar overdensities in all of the clusters in the sample. We also compared element mass-to-light ratios for the entire sample. We concluded that the preferential accretion of low entropy, low abundance gas into the potentials of groups and cold clusters can explain most of the observed trends in metallicity. In addition, we discussed the importance of preheating of the intracluster medium by Type II supernovae on the cluster scaling relations.

David, Laurence↗

DOE OSTI2023

Symphony: Cosmological Zoom-in Simulation Suites over Four Decades of Host Halo Mass

Abstract We present Symphony, a compilation of 262 cosmological, cold-dark-matter-only zoom-in simulations spanning four decades of host halo mass, from 10 11 –10 15 M ⊙ . This compilation includes three existing simulation suites at the cluster and Milky Way–mass scales, and two new suites: 39 Large Magellanic Cloud-mass (10 11 M ⊙ ) and 49 strong-lens-analog (10 13 M ⊙ ) group-mass hosts. Across the entire host halo mass range, the highest-resolution regions in these simulations are resolved with a dark matter particle mass of ≈3 × 10 −7 times the host virial mass and a Plummer-equivalent gravitational softening length of ≈9 × 10 −4 times the host virial radius, on average. We measure correlations between subhalo abundance and host concentration, formation time, and maximum subhalo mass, all of which peak at the Milky Way host halo mass scale. Subhalo abundances are ≈50% higher in clusters than in lower-mass hosts at fixed sub-to-host halo mass ratios. Subhalo radial distributions are approximately self-similar as a function of host mass and are less concentrated than hosts’ underlying dark matter distributions. We compare our results to the semianalytic model Galacticus , which predicts subhalo mass functions with a higher normalization at the low-mass end and radial distributions that are slightly more concentrated than Symphony. We use UniverseMachine to model halo and subhalo star formation histories in Symphony, and we demonstrate that these predictions resolve the formation histories of the halos that host nearly all currently observable satellite galaxies in the universe. To promote open use of Symphony, data products are publicly available at http://web.stanford.edu/group/gfc/symphony .

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

Large binocular telescope observations of new six compact star-forming galaxies with [Ne v ] λ3426 Å emission

ABSTRACT We report the discovery of [Ne v] λ3426 emission, in addition to He ii λ4686 emission, in six compact star-forming galaxies. These observations considerably increase the sample of eight such galaxies discovered earlier by our group. For four of the new galaxies, the optical observations are supplemented by near-infrared spectra. All galaxies, but one, have H ii regions that are dense, with electron number densities of ∼ 300–700 cm−3. They are all characterized by high H β equivalent widths EW(H β) ∼ 190–520 Å and high O32 = [O iii] λ5007/[O ii] λ3727 ratios of 10–30, indicating young starburst ages and the presence of high ionization radiation. All are low-metallicity objects with 12 + logO/H = 7.46–7.88. The spectra of all galaxies show a low-intensity broad component of the H α line and five of six objects show Wolf–Rayet features. Comparison with photoionization models shows that pure stellar ionization radiation from massive stars is not hard enough to produce such strong [Ne v] and He ii emission in our galaxies. The [Ne v] λ3426/He ii λ4686 flux ratio of ∼1.2 in J1222+3602 is consistent with some contribution of active galactic nucleus ionizing radiation. However, in the remaining five galaxies, this ratio is considerably lower, $\lesssim$ 0.4. The most plausible models are likely to be non-uniform in density, where He ii and [Ne v] lines are emitted in low-density channels made by outflows and illuminated by harder ionizing radiation from radiative shocks propagating through these channels, whereas [O iii] emission originates in denser regions exposed to softer stellar ionizing sources.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

Dark energy survey year 3 results: Cosmological constraints from cluster abundances, weak lensing, and galaxy clustering

Galaxy clusters provide a unique probe of the late-time cosmic structure and serve as a powerful independent test of the Λ⁢CDM model. This work presents the first set of cosmological constraints derived with ∼16,000 optically selected redMaPPer clusters across nearly 5000 deg 2 using DES year 3 datasets. Our analysis leverages a consistent modeling framework for galaxy cluster cosmology and DES-Y3 joint analyses of galaxy clustering and weak lensing (3 × 2⁢pt), ensuring direct comparability with the DES-Y3 3 × 2⁢pt analysis. Here, we obtain constraints of 𝑆 8 = 0.864 ± 0.035 and Ω m = $0.26⁢5^{+0.019}_{−0.031}$ from the cluster-based data vector. We find that cluster constraints and 3 × 2⁢pt constraints are consistent under the Λ⁢CDM model with a posterior predictive distribution (PPD) value of 0.53. The consistency between clusters and 3 × 2⁢pt provides a stringent test of Λ⁢CDM across different mass and spatial scales. Jointly analyzing clusters with 3 × 2⁢pt further improves cosmological constraints, yielding 𝑆 8 = $0.81⁢1^{+0.022}_{−0.020}$ and Ω m = $0.29⁢4^{+0.022}_{−0.033}$, a 24% improvement in the Ω m − 𝑆 8 figure of merit over 3 × 2⁢pt alone. Moreover, we find no significant deviation from the Planck CMB constraints with a probability to exceed (PTE) value of 0.6, significantly reducing previous 𝑆 8 tension claims. Finally, combining DES 3 × 2⁢pt, DES clusters, and Planck CMB places an upper limit on the sum of neutrino masses of ∑𝑚 𝜈 < 0.26 eV at 95% confidence under the Λ⁢CDM model. These results establish optically selected clusters as a key cosmological probe and pave the way for cluster-based analyses in upcoming stage-IV surveys such as LSST, Euclid, and Roman.

Abbott, T. M. C. [NSF’s National Optical-Infrared ↗

DOE OSTI2025

Dark Energy Survey Year 3 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Clustering

Galaxy clusters provide a unique probe of the late-time cosmic structure and serve as a powerful independent test of the $\Lambda$CDM model. This work presents the first set of cosmological constraints derived with ~16,000 optically selected redMaPPer clusters across nearly 5,000 $\rm{deg}^2$ using DES Year 3 data sets. Our analysis leverages a consistent modeling framework for galaxy cluster cosmology and DES-Y3 joint analyses of galaxy clustering and weak lensing (3x2pt), ensuring direct comparability with the DES-Y3 3x2pt analysis. We obtain constraints of $S_8 = 0.864 \pm 0.035$ and $\Omega_{\rm{m}} = 0.265^{+0.019}_{-0.031}$ from the cluster-based data vector. We find that cluster constraints and 3x2pt constraints are consistent under the $\Lambda$CDM model with a Posterior Predictive Distribution (PPD) value of $0.53$. The consistency between clusters and 3x2pt provides a stringent test of $\Lambda$CDM across different mass and spatial scales. Jointly analyzing clusters with 3x2pt further improves cosmological constraints, yielding $S_8 = 0.811^{+0.022}_{-0.020}$ and $\Omega_{\rm{m}} = 0.294^{+0.022}_{-0.033}$, a $24\%$ improvement in the $\Omega_{\rm{m}}-S_8$ figure-of-merit over 3x2pt alone. Moreover, we find no significant deviation from the Planck CMB constraints with a probability to exceed (PTE) value of $0.6$, significantly reducing previous $S_8$ tension claims. Finally, combining DES 3x2pt, DES clusters, and Planck CMB places an upper limit on the sum of neutrino masses of $\sum m_\nu < 0.26$ eV at 95% confidence under the $\Lambda$CDM model. These results establish optically selected clusters as a key cosmological probe and pave the way for cluster-based analyses in upcoming Stage-IV surveys such as LSST, Euclid, and Roman.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1989

Star formation rates and abundance gradients in disk galaxies

Analytic models for the evolution of disk galaxies are presented, placing special emphasis on the radial properties. These models are straightforward extensions of the original Schmidt (1959, 1963) models, with a dependence of star formation rate on gas density. The models provide successful descriptions of several measures of galactic disk evolution, including solar neighborhood chemical evolution, the presence and amplitude of metallicity and color gradients in disk galaxies, and the global rates of star formation in disk galaxies, and aid in the understanding of the apparent connection between young and old stellar populations in spiral galaxies.

Wyse, Rosemary F. G.↗

DOE OSTI2021

Bounds on Velocity-dependent Dark Matter–Proton Scattering from Milky Way Satellite Abundance

We use the latest measurements of the Milky Way satellite population from the Dark Energy Survey and Pan-STARRS1 to infer the most stringent astrophysical bound to date on velocity-dependent interactions between dark matter particles and protons. We model the momentum-transfer cross section as a power law of the relative particle velocity v with a free normalizing amplitude, σ MT = σ 0 v n , to broadly capture the interactions arising within the nonrelativistic effective theory of dark matter–proton scattering. The scattering leads to a momentum and heat transfer between the baryon and dark matter fluids in the early universe, ultimately erasing structure on small physical scales and reducing the abundance of low-mass halos that host dwarf galaxies today. From the consistency of observations with the cold collisionless dark matter paradigm, using a new method that relies on the most robust predictions of the linear perturbation theory, we infer an upper limit on σ0 of 1.4 × 10 -23 , 2.1 × 10 -19 , and 1.0 × 10 -12 cm 2 , for interaction models with n = 2, 4, and 6, respectively, for a dark matter particle mass of 10 MeV. These results improve observational limits on dark matter–proton scattering by orders of magnitude and thus provide an important guide for viable sub-GeV dark matter candidates.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1993

Cosmic evolution of extragalactic C 1, C 2, and CO luminosity

Carbon is the fourth most abundant element in the Galaxy with an abundance of approximately 4 x 10(exp -4) relative to hydrogen. Of all abundant metals it is the easiest to observe in the interstellar medium (ISM). Carbon can be found in four dominant forms: dust grains, C 2, C 1, and CO. The latter is the most abundant molecule (next to H2) in molecular clouds. All three gas-phase forms produce strong sub-mm wavelength emission lines and are the principal tracers of the warm and dense neutral phases of the ISM. We calculate the gas-phase abundances of neutral carbon (C 1), ionized carbon (C 2), and carbon monoxide (CO) as a function of cosmic time or redshift z in an idealized scenario of galactic evolution.

Bally, John↗

NASA NTRS1986

Is OH abundance enhanced in tidally distorted galaxies?

An extensive survey of 240 galaxies for hydroxyl absorption has been completed using the Arecibo Observatory. These galaxies were used to compile a sample to test for statistical correlations between the optical depth of the 1667 MHz hydroxyl line and various parameters of the parent galaxy. To be included in the sample, the radio flux density of the galaxy at 1667 MHz had to be between 20 mjy and 1000 mjy and the galactic declination between 0 and 38 deg. Since this sample contains mainly non-detections, statistical methods for astronomical data with upper limits as previously described were used to obtain correlation and regression information. Preliminary studies indicate a strong correlation between OH optical depth and infrared to blue luminosity ratio (L sub IR/L sub B), where the infrared data were obtained from the Cataloged Galaxies and Quasars Observed in the IRAS Survey. A second correlation is seen between the optical depth of the 1667 MHz line and galactic type, where a number from 1 to 15 (Elliptical to peculiar, distorted, or interacting) has been assigned to each galaxy. So, stable, isolated galaxies tend not to have detectable hydroxyl. On the other hand, galaxies with more gas and dust, galaxies with a more peculiar or distorted appearance, and galaxies which are more tidally interacting tend to have much more detectable OH. These findings could indicate that these dusty, peculiar, distorted, and interacting galaxies could be the site of large amounts of shocked material where OH is likely to form. Hence, the hydroxyl abundance could be enhanced in these regions of shocked material making the detection of OH in these tidally distorted galaxies much more likely.

Schmelz, J. T.↗

NASA NTRS1993

Chemical abundances in low surface brightness galaxies: Implications for their evolution

Low Surface Brightness (LSB) galaxies are an important but often neglected part of the galaxy content of the universe. Their importance stems both from the selection effects which cause them to be under-represented in galaxy catalogs, and from what they can tell us about the physical processes of galaxy evolution that has resulted in something other than the traditional Hubble sequence of spirals. An important constraint for any evolutionary model is the present day chemical abundances of LSB disks. Towards this end, spectra for a sample of 75 H 2 regions distributed in 20 LSB disks galaxies were obtained. Structurally, this sample is defined as having B(0) fainter than 23.0 mag arcsec(sup -2) and scale lengths that cluster either around 3 kpc or 10 kpc. In fact, structurally, these galaxies are very similar to the high surface brightness spirals which define the Hubble sequence. Thus, our sample galaxies are not dwarf galaxies but instead have masses comparable to or in excess of the Milky Way. The basic results from these observations are summarized.

Mcgaugh, S. S.↗

NASA NTRS1993

The relationships among mass, metallicity, and morphology for spiral galaxies

An evaluation is made of recent results for the gas-phase oxygen abundance of spiral galaxies in order to investigate the relationship between the characteristic abundance of a galaxy and its mass and Hubble type. Conjectures are presented concerning what these relationships may imply for the origin of galaxy morphology.

Zaritsky, Dennis↗

NASA NTRS2002

The Physical Origin of Galaxy Morphologies and Scaling Laws

We propose a numerical study designed to interpret the origin and evolution of galaxy properties revealed by space- and ground-based imaging and spectroscopical surveys. Our aim is to unravel the physical processes responsible for the development of different galaxy morphologies and for the establishment of scaling laws such as the Tully-Fisher relation for spirals and the Fundamental Plane of ellipticals. In particular, we plan to address the following major topics: (1) The morphology and observability of protogalaxies, and in particular the relationship between primordial galaxies and the z approximately 3 'Ly-break' systems identified in the Hubble Deep Field and in ground-based searches; (2) The origin of the disk and spheroidal components in galaxies, the timing and mode of their assembly, the corresponding evolution in galaxy morphologies and its sensitivity to cosmological parameters; (3) The origin and redshift evolution of the scaling laws that link the mass, luminosity size, stellar content, and metal abundances of galaxies of different morphological types. This investigation will use state-of-the-art N-body/gasdynamical codes to provide a spatially resolved description of the galaxy formation process in hierarchically clustering universes. Coupled with population synthesis techniques. our models can be used to provide synthetic 'observations' that can be compared directly with observations of galaxies both nearby and at cosmologically significant distances. This study will thus provide insight into the nature of protogalaxies and into the formation process of galaxies like our own Milky Way. It will also help us to assess the cosmological significance of these observations within the context of hierarchical theories of galaxy formation and will supply a theoretical context within which current and future observations can be interpreted.

Steinmetz, Matthias↗

NASA NTRS1993

Gas-rich dwarf galaxies in dense and sparse environments

Dwarf irregular galaxies (generically labelled Im for the present purposes) pose an enigma to students of galaxy evolution. In nearby groups and the Virgo cluster, Im galaxies are at least as abundant as spiral galaxies, and their low surface brightnesses and high gas-to-stars ratios suggest that (at least in the stochastic self-propagating star formation scenario) there should be significant numbers of HI clouds with masses approaching 10(exp 8) solar mass which have undergone very little or no star formation. To date, however, no clouds with so little star formation that they would not be recognized as Im galaxies on high-quality photographic plates have been identified. There have been suggestions that such dwarfs may be tidally disrupted in regions of high galactic density, but may be prevalent in low density regions. We offer data from three parallel programs relevant to this issue. (1) A large number of Im galaxies throughout the Local Supercluster have been mapped in the HI spectral line using the Arecibo Radiotelescope, and we can establish the frequency with which HI disks much more extended than their optically visible portions are found. (2) Our extensive mapping of spiral and dwarf galaxies in the Virgo cluster allows us to set stringent limits on the density of star-free Hi clouds in that cluster. (3) We have conducted a sampling of the void in the distribution of galaxies toward the super galactic pole, optimized for finding low-mass HI clouds at redshifts out to approximately 2000 km/s.

Hoffman, G. Lyle↗

NASA NTRS1980

On the abundance of carbon monoxide in galaxies - A comparison of spiral and Magellanic irregular galaxies

CO emission has been sought in 52 directions toward six irregular, Magellanic-type galaxies, with null results at a typical detection limit of 0.04 K for a line width of 10 km/s. The positions searched correspond to those of bright OB star clusters, H II regions, H I peaks, and dark clouds. In two cases, one-third of the optical galaxy was covered by the observations. CO has been detected at 2.6 mm toward the nucleus of the low-mass SA(s)dm galaxy NGC 7793. The results imply that the mean surface brightness of CO emission in Magellanic irregulars is less than that of the Galaxy and other spirals which have been studied. Two categories of explanations for this are discussed, including (1) those based on a lower heating rate for interstellar clouds in irregulars, and thus a lower CO temperature, and (2) those based on a lower CO abundance.

Elmegreen, B. G.↗

NASA NTRS1984

A possible relationship between metal abundance and luminosity for disk galaxies

Near-infrared colors have been measured for a sample of 31 late-type galaxies in the Pegasus I and Pisces clusters; system luminosities in the sample cover the range of M(H) between -19 and -23.5. The color index (J - K) correlates strongly with the absolute H magnitude; lower-luminosity systems have bluer colors. These observations are consistent with the assumption that the mean metal abundance of the old disk population decreases systematically with luminosity. The systematic variation (B - H) with absolute H magnitude reported recently by Tully et al. (1982) derives in part from this proposed systematic change of metallicity with luminosity. However, a relative increase in the number of newly formed stars and/or a systematic smaller age for lower-luminosity disks must still be posited in order to fully explain the observed (B - H), H relation.

Bothun, G. D.↗

NASA NTRS1993

Oxygen abundances in low surface-brightness galaxies

Recent theories predict that some protogalaxies, in low-density environments of the field, are contracting and interacting so slowly that global star formation can be delayed until today. These systems should be gas rich and have low surface-brightness. Blue compact galaxies (BCG's) and other compact HII region galaxies currently experiencing a burst of star formation are good candidates of truly young galaxies (in the sense that global star formation recently has been initiated). If they really are young, they ought to have a recent phase when their brightness was much lower than in the bursting phase. No claims of observations of such proto-BCG's exist. Observations of galaxies in their juvenile phases would undoubtedly be of great interest, e.g. the determination of the primordial helium abundance would improve. A proper place to search for young nearby galaxies could be among blue low surface-brightness galaxies (BLSBG's) in the local field. The study of low surface-brightness galaxies (LSBG's) as a group began relatively recently. They are galaxies with extraordinary properties both as individuals and as a group. A few years ago we started an optical study of a sample of BLSBG's selected from the ESO/Uppsala catalogue. Results of spectroscopic observations obtained on a subsample - 8 galaxies - of our selection are reported. The HII region oxygen chemical abundances and its relation to the blue absolute magnitude and surface-brightness is investigated.

Roennback, Jari↗

DOE OSTI2020

The chemical nature of the young 120-Myr-old nearby Pisces–Eridanus stellar stream flowing through the Galactic disc

Recently, a new cylindrical-shaped stream of stars up to 700 pc long was discovered hiding in the Galactic disc using kinematic data enabled by the Gaia mission. This stream of stars, dubbed Pisces–Eridanus (Psc–Eri), was initially thought to be as old as 1 Gyr, yet its stars shared a rotation period distribution consistent with a population that was 120 Myr old. Here, we explore the detailed chemical nature of this stellar stream. We carried out high-resolution spectroscopic follow-up of 42 Psc–Eri stars using McDonald Observatory and combined these data with information for 40 members observed with the low-resolution LAMOST spectroscopic survey. Together, these data enabled us to measure the abundance distribution of light/odd-Z (Li, Na, Al, Sc, V), α (Mg, Si, Ca, Ti), Fe-peak (Cr, Mn, Fe, Co, Ni, Zn), and neutron capture (Sr, Y, Zr, Ba, La, Nd, Eu) elements along the Psc–Eri stream. We find that the stream is (1) near-solar metallicity with [Fe/H] = –0.03 dex and (2) has a metallicity spread of 0.07 dex (or 0.04 dex when outliers are excluded). We also find that (3) the abundance of Li indicates that Psc–Eri is ~120 Myr old, consistent with its gyrochronology age. Additionally, Psc–Eri has (4) [X/Fe] abundance spreads that are just larger than the typical uncertainty in most elements, (5) it is a cylindrical-like system whose outer edges rotate about the centre, and (6) no significant abundance gradients along its major axis except a potentially weak gradient in [Si/Fe]. These results show that Psc–Eri is a uniquely close young chemically interesting laboratory for testing our understanding of star and planet formation.

79 ASTRONOMY AND ASTROPHYSICS↗