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NASA NTRS1994

Photoionization of disk galaxies: An explanation of the sharp edges in the H I distribution

We have reproduced the observed radial truncation of the H I distribution in isolated spiral galaxies with a model in which extragalactic radiation photoionizes the gaseous disk. For a galactic mass distribution model that reproduces the observed rotation curves, including dark matter in the disk and halo, the vertical structure of the gas is determined self-consistently. The ionization structure and column densities of H and He ions are computed by solving the radiation transfer equation for both continuum and lines. Our model is similar to that of Maloney, and the H I structure differs by less than 10%. The radial structure of the column density of H I is found to be more sensitive to the extragalactic radiation field than to the distribution of mass. For this reason, considerable progress can be made in determining the extragalactic flux of ionizing photons, phi(sub ex), with more 21 cm observations of isolated galaxies. However, owing to the uncertainty of the radial distribution of total hydrogen at large radii, inferring the extragalactic flux by comparing the observed edges to photoionization models is somewhat subjective. We find 1 x 10(exp 4)/sq cm/s is less than or approximately phi(sub ex) is less than or approximately 5 x 10(exp 4)/sq cm/s, corresponding to 2.1 is less than or approximately iota(sub 0) is less than or approximately 10.5 x 10(exp -23) ergs/sq cm/s/Hz/sr for a 1/nu spectrum. Although somewhat higher, our inferred range of iota(sub 0) is consistent with the large range of values obtained by Kulkarni & Fall from the 'proximity effect' toward Quasi-Stellar Objects (QSOs) at approximately 0.5.

Dove, James B.↗

DOE OSTI2021

CHIME/FRB Catalog 1 Results: Statistical Cross-correlations with Large-scale Structure

The CHIME/FRB Project has recently released its first catalog of fast radio bursts (FRBs), containing 492 unique sources. Here, we present results from angular cross-correlations of CHIME/FRB sources with galaxy catalogs. We find a statistically significant (p-value ~ 10 –4 , accounting for look-elsewhere factors) cross-correlation between CHIME FRBs and galaxies in the redshift range 0.3 ≲ z ≲ 0.5, in three photometric galaxy surveys: WISE × SCOS, DESI-BGS, and DESI-LRG. The level of cross-correlation is consistent with an order-one fraction of the CHIME FRBs being in the same dark matter halos as survey galaxies in this redshift range. We find statistical evidence for a population of FRBs with large host dispersion measure (~400 pc cm –3 ) and show that this can plausibly arise from gas in large halos (M ~ 10 14 M ⊙ ), for FRBs near the halo center (r ≲ 100 kpc). These results will improve in future CHIME/FRB catalogs, with more FRBs and better angular resolution.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1991

The dust enshrouded quasar in the ultraluminous galaxy Markarian 463 - Radio, near-infrared, and optical imaging

New imaging data are presented at radio, near-infrared, and optical wavelengths to elucidate the processes associated with the ongoing merger and nuclear activity in Mrk 463. Imaging at 20 cm reveals previously unknown components 4 arcsec north and 18 arcsec south of Mrk 463E, and a source 10 arcsec to the northwest which is believed to be linked to the nuclear region. The western nucleus, Mrk 463W, was detected at 6 and 20 cm; it has a radio luminosity comparable to that of a moderately luminous Seyfert galaxy or a highly luminous starburst galaxy. Near-infrared images at wavelengths less than 2.3 microns show the two nuclei; only Mrk 463E has been detected at 3.7 microns. Brightness profiles of Mrk 463E are unresolved at K and L-prime, but extended at J. It is inferred from the fact that radio continuum components 4-18 kpc from the nucleus are aligned with previously known 0.05-1.5 kpc radio structure and extended conical O-III forbidden omission lines that Mrk 463E is powering weak radio lobes and therefore exemplifies a transition between the confined linear sources in Seyfert galaxies and the extended lobes in classical quasars and radio galaxies.

Mazzarella, J. M.↗

NASA NTRS1993

Is a local bar a good place to find a companion? The near infrared morphology of Maffei 2

Maffei 2 is one of the closest large spiral galaxies lying just beyond the Local Group. It would probably be one of the most heavily studied galaxies in the sky were it not for the approximately 5 magnitudes of visual extinction resulting from its position behind the Galactic plane. It is the site of a burst of nuclear star formation indicated by strong infrared and radii continuum emission. Interferometric maps of CO-12 and CO-13 emission indicate that star formation is associated with a barlike structure consisting of arms of molecular gas that extend from within approximately 50 pc of the dynamical center out to a radius of at least 500 pc. HI maps have shown the galaxy to have an angular extent of approximately 15 feet and a neutral gas mass typical of a large spiral galaxy.

Hurt, Robert L.↗

NASA NTRS1990

Resonant excitation of internal gravity waves in cluster cooling flows

Orbital motions of galaxies in X-ray clusters will resonantly excite internal gravity waves (g-waves) that propagate in the plasma. The resonance corresponds to a match between the local Brunt-Vaisala oscillation frequency in the plasma and the appropriate Fourier component of the galactic gravitational potential. Radiated internal waves have an inward group velocity that carries them to the central region of the flow where they become tightly wrapped, geometrically amplified, and eventually dissipated. Waves transport energy and angular momentum, but probably not in amounts large enough to grossly alter the structure of a cooling flow, should one be present. All physical flow variables are finite at the resonance, and all energy and angular momentum deposited by a galaxy is carried inward by the waves. Nonlinear density and velocity fluctuations are likely to result from wave amplitude growth in the central regions of the flow, and a connection with the formation of emission-line filaments is a possibility.

Balbus, Steven A.↗

DOE OSTI2021

Dark Energy Survey Year 3 results: Curved-sky weak lensing mass map reconstruction

ABSTRACT We present reconstructed convergence maps, mass maps, from the Dark Energy Survey (DES) third year (Y3) weak gravitational lensing data set. The mass maps are weighted projections of the density field (primarily dark matter) in the foreground of the observed galaxies. We use four reconstruction methods, each is a maximum a posteriori estimate with a different model for the prior probability of the map: Kaiser–Squires, null B-mode prior, Gaussian prior, and a sparsity prior. All methods are implemented on the celestial sphere to accommodate the large sky coverage of the DES Y3 data. We compare the methods using realistic ΛCDM simulations with mock data that are closely matched to the DES Y3 data. We quantify the performance of the methods at the map level and then apply the reconstruction methods to the DES Y3 data, performing tests for systematic error effects. The maps are compared with optical foreground cosmic-web structures and are used to evaluate the lensing signal from cosmic-void profiles. The recovered dark matter map covers the largest sky fraction of any galaxy weak lensing map to date.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1993

Is 1308+326 A BL Lacertae object or a quasar?

The active galaxy 1308+326 (z = 0.996) has been classified as a BL Lacertae object because of its nearly featureless optical continuum and high and variable polarization. New VLBI polarization images of 1308+326, however, show both VLBI polarization structure and tentative superluminal motions that are characteristic of quasars rather than BL Lacertae objects. These data strongly suggest that this source is simply a quasar with emission lines of small equivalent width. We discuss the possibility that the optical continuum is enhanced by microlensing in a foreground galaxy, as suggested by Stickel et al.

Gabuzda, D. C.↗

DOE OSTI2026

Dwarf Galaxies at Cosmic Noon: New JWST Constraints on Satellite Models and Subhalo Tidal Evolution

The advent of JWST has revolutionized the study of faint satellite galaxies at z ≳ 1, enabling statistical constraints on galaxy evolution and the galaxy–halo connection in a previously unexplored mass and redshift regime. We compare satellite abundances at 1 < z < 3.5 from recent JWST observations with predictions from cosmological dark-matter-only zoom-in simulations. We identify and quantify several sources of biases that can impact theoretical satellite counts, finding that assumptions about subhalo tidal evolution introduce the largest uncertainty in predictions for the satellite mass function. Using a flexible galaxy disruption model, we explore a range of disruption scenarios, spanning hydrodynamically motivated and idealized prescriptions, to bracket plausible physical outcomes. We show that varying galaxy durability can change the predicted satellite mass functions by a factor of ∼3.5. The JWST data and our fiducial model are consistent within 1σ–2σ across the full redshift (1 < z < 3.5) and stellar mass (M⋆ > 10 7 M ⊙ ) range probed. We find evidence that subhalos are at least as long-lived as predicted by hydrodynamic simulations. Our framework will enable robust constraints on the tidal evolution of subhalos with future observations. This work presents the first direct comparison between cosmological models and observations of the high-redshift satellite population in this low-mass regime. These results showcase JWST’s emerging power to test structure formation in the first half of the Universe in a new domain and to constrain the physical processes driving the evolution of low-mass galaxies across cosmic time.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

DESI2024: Dark Energy Spectroscopic Instrument (DESI) survey, presentation of Year 1 results

The series of papers included in this special issue represent the first cosmological measurements from the Dark Energy Spectroscopic Instrument (DESI). These papers present the validation of the DESI clustering catalogs, the methodology for the cosmology measurements, and the full cosmology implications. These measurements were derived from a catalog of approximately 6.4 million extragalactic sources in a redshift range of 0.1 < z < 4.2. Owing to advances in fiber positioner technology and to a larger telescope, this sample was acquired in only one year of observation, yet is more than double the size of the galaxy and quasar samples from the first four phases of the Sloan Digital Sky Survey (SDSS) that spanned 20 years. With these new galaxy and quasar catalogs, the DESI collaboration completed percent-level constraints on the cosmic expansion history and the growth of structure. In turn, these new measurements provided a new platform from which to test the equation of state of dark energy, the summed mass of the three neutrino mass eigenstates, global curvature, and General Relativity. By surpassing the precision of the previous generation spectroscopic survey, the results in this special issue mark the transition in the field of cosmology to Stage-IV dark energy science.

baryon acoustic oscillations↗

DOE OSTI2024

Constraints on compact objects from the Dark Energy Survey 5-yr supernova sample

ABSTRACT Gravitational lensing magnification of Type Ia supernovae (SNe Ia) allows information to be obtained about the distribution of matter on small scales. In this paper, we derive limits on the fraction $\alpha$ of the total matter density in compact objects (which comprise stars, stellar remnants, small stellar groupings, and primordial black holes) of mass M > 0.03 ${\rm M}_{\odot }$ over cosmological distances. Using 1532 SNe Ia from the Dark Energy Survey Year 5 sample (DES-SN5YR) combined with a Bayesian prior for the absolute magnitude M, we obtain α < 0.12 at the 95 per cent confidence level after marginalization over cosmological parameters, lensing due to large-scale structure, and intrinsic non-Gaussianity. Similar results are obtained using priors from the cosmic microwave background, baryon acoustic oscillations, and galaxy weak lensing, indicating our results do not depend on the background cosmology. We argue our constraints are likely to be conservative (in the sense of the values we quote being higher than the truth), but discuss scenarios in which they could be weakened by systematics of the order of $\Delta \alpha \sim 0.04$.

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DOE OSTI2023

Hyper Suprime-Cam Year 3 results: Measurements of clustering of SDSS-BOSS galaxies, galaxy-galaxy lensing, and cosmic shear

Here we utilize the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS-BOSS) galaxies and its overlap with approximately 416 sq degrees of deep grizy-band imaging from the Subaru Hyper Suprime-Cam Survey (HSC). We perform measurements of three two-point correlations which form the basis of the cosmological inference presented in our companion papers, Miyatake et al. and Sugiyama et al. We use three approximately volume limited subsamples of spectroscopic galaxies by their i-band magnitude from the SDSS-BOSS: LOWZ (0.1 < z < 0.35), CMASS1 (0.43 < z < 0.55) and CMASS2 (0.55 < z < 0.7), respectively. We present high signal-to-noise ratio measurements of the projected correlation functions of these galaxies, which is expected to be proportional to the projected matter correlation function on large scales with a proportionality constant dependent on the bias of galaxies. In order to help break the degeneracy between the amplitude of the matter correlation and the bias of these spectroscopic galaxies, we use the distortions of the shapes of fainter galaxies in HSC due to weak gravitational lensing, to measure the galaxy-galaxy lensing signal, which probes the projected galaxy-matter cross-correlation function of the SDSS-BOSS galaxies. We also measure the cosmic shear correlation functions from HSC galaxies which is related to the projected matter correlation function. We demonstrate the robustness of our measurements by subjecting each of them to a variety of systematic tests. Our use of a single sample of HSC source galaxies is crucial to calibrate any residual systematic biases in the inferred redshifts of our galaxies. We also describe the construction of a suite of mocks: (i) spectroscopic galaxy catalogs which obey the clustering and abundance of each of the three SDSS-BOSS subsamples, and (ii) galaxy shape catalogs which obey the footprint of the HSC survey and have been appropriately sheared by the large-scale structure expected in a Lambda Cold Dark Matter model. Finally, we use these mock catalogs to compute the covariance of each of our observables.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Improving Dark Energy Constraints Using Low-Redshift Large-Scale Structures

The primary goal of this project was to improve constraints on dark energy measurements by improving our ability to extract cosmological information from low redshift large-scale structures. PI Clowe's project's primary aim was to reduce the bias in measurements of the masses of clusters of galaxies to a level where the evolution of the cluster mass function can be used in the Vera Rubin Observatory's Legacy Survey of Space and Time Dark Energy Science Collaboration survey to improve the accuracy of the measurement of dark energy and other cosmological parameters. Co-PI Seo's project studied observational systematics affecting large-scale clustering of galaxies, which will be used to improve dark energy constraints from the Dark Energy Spectroscopic Instrument (DESI). The cluster lensing project employed a series of simulations and observations of clusters of galaxies to test numerous potential systematic errors in cluster mass measurements using weak gravitational lensing as the accuracy of current weak lensing measurements are more than order of magnitude worse than what is required to use clusters of galaxies for accurate determination of dark energy parameters. PI Clowe and group developed and analyzed simulations to test for, and correct biases introduced in, the weak lensing measurement process. Finally, PI Clowe and group developed a method of detecting clusters using galaxy overdensities and applied the method to the BLISS and DES surveys. The success of spectroscopic dark energy mission such as the extended Baryon Oscillation Spectroscopic Survey (eBOSS) and the Dark Energy Spectroscopic Instrument (DESI) will depend on a thorough understanding of various observational systematics in the target density fluctuations that would give rise to spurious, non-cosmological signals. PI Seo and group developed a deep learning, artificial neural network (ANN) technique that modeled and mitigated such effects, aimed at deriving more robust galaxy clustering signals not only for the baryon acoustic oscillation feature and redshift-space distortions but also for primordial non-Gaussianity constraint.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1988

Evidence for a radio flare in the nucleus of Virgo A

An increase in radio emission has been observed in the nucleus of the galaxy Virgo A by use of VLBI measurements. These 2.29 GHz observations show that the correlated flux density of the milliarcsec structure increased by 30 percent during a four month period in 1977, and eventually returned to the preflare level of about 0.6 Jy. Previous evidence had indicated that the nuclear radio emission was stable, a surprising result for an active galactic nucleus.

Morabito, David D.↗

NASA NTRS1990

Unbound molecular complexes in M33

The HI content of the nearby spiral galaxy M33 (d approx. 0.8 Mpc) has been the subject of many detailed studies (most recently Deul and van der Hulst 1987), but similar data on the molecular gas component has been lacking. This galaxy is currently undergoing vigorous high-mass star formation, as evidenced by the many OB associations and HII regions, and so is expected to possess at least some molecular gas. Interferometric studies have detected molecular clouds similar to Galactic Giant Molecular Clouds (GMCs) (Boulanger et al. 1988; Wilson et al. 1988). Researchers have recently mapped the nuclear region of M33 in the CO J=1-0 line with a 12 m telescope (half power beam width 55 inches approx. 210 pc) out to a radius of 3.5 minutes in order to trace the detailed distribution of the molecular gas. The resulting map reveals six large complexes with diameters of 200 to 400 pc. Interferometer observations of these regions have resolved them into individual molecular clouds similar to Galactic GMCs (Wilson et al. 1988). The complexes shown are much larger than individual Galactic GMCs (Sanders, Scoville, and Solomon 1985), but are somewhat smaller on average than the large associations seen in the grand-design spiral galaxy M51 (Rand and Kulkarni 1989). If we extend the velocity-diameter relation observed for Galactic GMCs to these larger structures, the predicted velocity widths are a factor of 1.5 to 3 times greater than the observed full-width half-maximum velocities (13 to 29 km (s-1). The peak brightness temperatures are approx. 0.2 K, at least a factor of 10 lower than what is observed for Galactic GMCs. If these large structures are made up of objects similar to Galactic GMCs, the area filling factor of the small clouds is roughly 10 percent. These results suggest that these complexes are not very large GMCs, but rather are associations of many individual GMCs or GMCs embedded in a diffuse gas component.

Wilson, Christine D.↗

NASA NTRS1991

Quasars and galaxy formation. I - The z greater than 4 objects

The physical properties of the known quasars with z greater than 4 are examined with particular reference to theories of cosmic structure formation. A 'standard' massive accreting black hole model for quasars is used to calculate the masses, radiative efficiencies, and accretion rates of the observed objects. The masses, densities, cosmological overdensities, and sizes of the accretion fuel reservoirs associated with the quasar black holes are considered, and several indirect arguments are used to connect these quantities to the masses and overdensities of the quasar host objects. Finally, constraints on the epoch of formation of the host objects are discussed. The general conclusion is that the observed quasars with z greater than 4 suggest that the cosmic structure formation was already well advanced at z = 5, when the universe was a small fraction of its present age.

Turner, Edwin L.↗

NASA NTRS2007

System Engineering the Space Infrared Interferometric Telescope (SPIRIT)

The Space Infrared Interferometric Telescope (SPIRIT) was designed to accomplish three scientific objectives: (1) learn how planetary systems form from protostellar disks and how they acquire their inhomogeneous chemical composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. SPIRIT will accomplish these objectives through infrared observations with a two aperture interferometric instrument. This paper gives an overview of SPIRIT design and operation, and how the three design cycle concept study was completed. The error budget for several key performance values allocates tolerances to all contributing factors, and a performance model of the spacecraft plus instrument system demonstrates meeting those allocations with margin.

Hyde, Tristram T.↗

NASA NTRS2007

The Space Infrared Interferometric Telescope (SPIRIT) and its Complementarity to ALMA

We report results of a pre-Formulation Phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. In each of these science domains, SPIRIT will yield information complementary to that obtainable with the James Webb Space Telescope (JWST)and the Atacama Large Millimeter Array (ALMA), and all three observatories could operate contemporaneously. Here we shall emphasize the SPIRIT science goals (1) and (2) and the mission's complementarity with ALMA.

Leisawitz, Dave↗

DOE OSTI2020

The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Cosmological Implications from two Decades of Spectroscopic Surveys at the Apache Point observatory

We present the cosmological implications from final measurements of clustering using galaxies, quasars, and Ly$\alpha$ forests from the completed Sloan Digital Sky Survey (SDSS) lineage of experiments in large-scale structure. These experiments, composed of data from SDSS, SDSS-II, BOSS, and eBOSS, offer independent measurements of baryon acoustic oscillation (BAO) measurements of angular-diameter distances and Hubble distances relative to the sound horizon, $r_d$, from eight different samples and six measurements of the growth rate parameter, $f\sigma_8$, from redshift-space distortions (RSD). This composite sample is the most constraining of its kind and allows us to perform a comprehensive assessment of the cosmological model after two decades of dedicated spectroscopic observation. We show that the BAO data alone are able to rule out dark-energy-free models at more than eight standard deviations in an extension to the flat, $\Lambda$CDM model that allows for curvature. When combined with Planck Cosmic Microwave Background (CMB) measurements of temperature and polarization the BAO data provide nearly an order of magnitude improvement on curvature constraints. The RSD measurements indicate a growth rate that is consistent with predictions from Planck primary data and with General Relativity. When combining the results of SDSS BAO and RSD with external data, all multiple-parameter extensions remain consistent with a $\Lambda$CDM model. Regardless of cosmological model, the precision on $\Omega_\Lambda$, $H_0$, and $\sigma_8$, remains at roughly 1\%, showing changes of less than 0.6\% in the central values between models. The inverse distance ladder measurement under a o$w_0w_a$CDM yields $H_0= 68.20 \pm 0.81 \, \rm km\, s^{-1} Mpc^{-1}$, remaining in tension with several direct determination methods. (abridged)

79 ASTRONOMY AND ASTROPHYSICS↗