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At least 451 records · Page 25
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DOE OSTI2021

Radio Morphology of Red Geysers

We present 150 MHz, 1.4 GHz, and 3 GHz radio imaging (LoTSS, FIRST, and VLASS) and spatially resolved ionized gas characteristics (SDSS IV-MaNGA) for 140 local ($z$ < 0.1) early-type red geyser galaxies. These galaxies have a low star formation activity (with a star formation rate, SFR, ~ 0.01 $M$ ⊙ yr -1 ) but show unique extended patterns in spatially resolved emission-line maps that have been interpreted as large-scale ionized winds driven by active galactic nuclei (AGN). In this work, we confirm that red geysers host low-luminosity radio sources ($L$ 1.4GHz ~ 10 22 $WHz$ -1 ). Out of 42 radio-detected red geysers, 32 are spatially resolved in LoTSS and FIRST, with radio sizes varying between ~5–25 kpc. Three sources have radio sizes exceeding 40 kpc. A majority display a compact radio morphology and are consistent with either low-power compact radio sources (FR0 galaxies) or radio-quiet quasars. They may be powered by small-scale AGN-driven jets that remain unresolved at the current 5'' resolution of radio data. The extended radio sources, not belonging to the "compact" morphological class, exhibit steeper spectra with a median spectral index of -0.67, indicating the dominance of lobed components. Furthermore, the red geysers hosting extended radio sources also have the lowest specific SFRs, suggesting they either have a greater impact on the surrounding interstellar medium or are found in more massive halos on average. The degree of alignment of the ionized wind cone and the extended radio features are either 0° or 90°, indicating possible interaction between the interstellar medium and the central radio AGN.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

A Generative Model for Realistic Galaxy Cluster X-Ray Morphologies

Abstract The X-ray morphologies of clusters of galaxies display significant variations, reflecting their dynamical histories and the nonlinear dependence of X-ray emissivity on the density of the intracluster gas. Qualitative and quantitative assessments of X-ray morphology have long been considered a proxy for determining whether clusters are dynamically active or “relaxed.” Conversely, the use of circularly or elliptically symmetric models for cluster emission can be complicated by the variety of complex features realized in nature, spanning scales from megaparsecs down to the resolution limit of current X-ray observatories. In this work, we use mock X-ray images from simulated clusters from The Three Hundred project to define a basis set of cluster image features. We take advantage of the clusters’ approximate self-similarity to minimize the differences between images before encoding the remaining diversity through a distribution of high-order polynomial coefficients. Principal component analysis then provides an orthogonal basis for this distribution, corresponding to natural perturbations from an average model. This representation allows novel, realistically complex X-ray cluster images to be easily generated, and we provide code to do so. The approach provides a simple way to generate training data for cluster image analysis algorithms and could be straightforwardly adapted to generate clusters displaying specific types of features or selected by physical characteristics available in the original simulations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Impact of Cosmic Filaments on Galaxy Morphological Evolution and Predictions of Early Cosmic Web Structure for Roman

We leverage the IllustrisTNG cosmological simulations to test how the large-scale cosmic web shapes galaxy morphology and to forecast the early cosmic web structure that the Nancy Grace Roman Space Telescope will reveal. In the hydrodynamic TNG50 and N-body TNG50-Dark runs, we reconstruct the cosmic web at redshifts z = 0, 0.5, 1, 2, 3, and 4 with the Monte Carlo Physarum Machine density estimator and the DisPerSE structure identification framework. We confirm that dark matter halos start out predominantly prolate (elongated), and their shapes are aligned with their nearest filaments; prolate galaxies retain strong shape alignment with their outer halos to later times. At z ≥ 1, the fraction of prolate (spheroidal) halos increases (decreases) toward lower stellar mass, higher redshift, and lower filament density. At z < 1, more spheroidal (oblate) stellar structures preferentially reside in higher-density (lower-density) filaments. We also find that higher-density filaments favor extended rotationally supported disks, whereas lower-density filaments more often host smaller dispersion-supported systems. Then, generating mock galaxy samples from TNG100 and TNG50, we predict the early cosmic web accessible to Roman. We find that the spectroscopic emission-line depth planned for the High-Latitude Wide-Area Survey (HLWAS) yields a highly incomplete galaxy sample that does not accurately trace the z = 1 cosmic web. A survey ≥2.5× deeper over a few square degrees would enable a proper reconstruction and reveal qualitatively correct filament–galaxy morphology relationships. Nevertheless, the planned HLWAS Deep field should still identify most galaxy overdensities; targeted deeper spectroscopy of these regions would efficiently and adequately map the early filamentary structure.

Hasan, Farhanul [Space Telescope Science Institute↗
DOE OSTI2022

Bridging the Bondi and Event Horizon Scales: 3D GRMHD Simulations Reveal X-shaped Radio Galaxy Morphology

X-shaped radio galaxies (XRGs) produce misaligned X-shaped jet pairs and make up ≲10% of radio galaxies. XRGs are thought to emerge in galaxies featuring a binary supermassive black hole (SMBH), SMBH merger, or large-scale ambient medium asymmetry. We demonstrate that XRG morphology can naturally form without such special, preexisting conditions. Our 3D general-relativistic magnetohydrodynamic (GRMHD) simulation for the first time follows magnetized rotating gas from outside the SMBH sphere of influence of radius RB to the SMBH of gravitational radius Rg at the largest scale separation, RB/Rg = 103, to date. Initially, our axisymmetric system of constant-density hot gas contains a weak vertical magnetic field and rotates in the equatorial plane of a rapidly spinning SMBH. We seed the gas with small-scale 2% level pressure perturbations. Infalling gas forms an accretion disk, and the SMBH launches relativistically magnetized collimated jets reaching well outside RB. Under the pressure of the infalling gas, the jets intermittently turn on and off, erratically wobble, and inflate pairs of cavities in different directions, resembling an X-shaped jet morphology. Synthetic X-ray images reveal multiple pairs of jet-powered shocks and cavities. Large-scale magnetic flux accumulates on the SMBH, becomes dynamically important, and leads to a magnetically arrested disk state. The SMBH accretes at 2% of the Bondi rate ($\dot{M}\simeq 2.4\times {10}^{-3}{M}_{\odot }\,{\mathrm{yr}}^{-1}$ for M87*) and launches twin jets at η = 150% efficiency. These jets are powerful enough (P jets ≃ 2 × 10 44 erg s -1 ) to escape along the SMBH spin axis and end the short-lived intermittent jet state, whose transient nature can account for the rarity of XRGs.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Recent satellite measurements of the morphology and dynamics of the plasmasphere.

The characteristic morphology and dynamics of the plasmasphere vary with local time and with geomagnetic conditions. On the nightside the plasmapause position changes predictably with changing magnetic activity. Once established at a specific L-shell value, the steep density gradient on the nightside corotates into the dayside, where filling from the ionosphere takes place. In the duskside bulge region the characteristic density profile inside the plasmapause displays a smooth decrease proportional to 1/R to the fourth power where R is radial distance. Plasmasphere morphology and dynamics can be understood in terms of a time-varying convection electric-field model of the magnetosphere that includes the bulge region as part of the main circulation pattern of the plasmasphere.

Chappell, C. R.↗
NASA NTRS1972

Interplanet variations in scale of crater morphology - Earth, Mars, Moon.

Craters on the Earth, Mars, and the Moon show a spectrum of morphologies with diameter increasing from simple, bowl-shaped craters through craters with increasingly complex central peaks, to craters with 'peak rings' and basins with multiple concentric scarps. In each category there is a range of diameters, centered around a characteristic diameter, D sub c. It is found that D sub c decreases as the size of the planet increases. Several possible explanations are considered. It is suggested that the effect results from a certain gravity scaling law. It is believed that all geological structures in which gravity is the dominant parameter affecting the morphology should follow this law.

Hartmann, W. K.↗
NASA NTRS1974

The effects of soil moisture and plant morphology on the radar backscatter from vegetation

The results of experimental studies on the backscattering properties of corn, milo, soybeans and alfalfa are presented. The measurements were made during the summer of 1973 over the 8 to 18 GHz frequency band. The data indicate that soil moisture estimation is best accomplished at incidence angles near nadir with lower frequencies, while crop discrimination is best accomplished using two frequencies at incidence angles ranging from 30 deg to 65 deg. It is also shown that temporal plant morphology variations can cause extreme variations in the values of the scattering coefficients. These morphological changes can be caused by growth, heavy rain and in the case of alfalfa, harvesting.

Ulaby, F. T.↗
NASA NTRS1976

Volcanology and morphology

Apollo 15 photographs of the southern parts of Serenitatis and Imbrium were used for a study of the morphology and distribution of wrinkle ridges. Volcanic and structural features along the south margin of Serenitatis were also studied, including the Dawes basalt cinder cones. Volcanic and structural features in crater Aitken were investigated as well. Study of crater Goclenius showed a close relationship between morphology of the impact crater and grabens which tend to parallel directions of the lunar grid. Similar trends were observed in the walls of crater Tsiolkovsky and other linear structures. Small craters of possible volcanic origin were also studied. Possible cinder cones were found associated with the Dawes basalt and in the floor of craters Aitken and Goclenius. Small pit craters were observed in the floors of these craters. Attempts were made to obtain contour maps of specific small features and to compare Orbiter and Apollo photographs to determine short term changes associated with other processes.

Bryan, W. B.↗
NASA NTRS1976

Preflare X-ray morphology of active regions observed with the AS & E telescope on Skylab

Images of active regions obtained with the grazing-incidence X-ray telescope aboard Skylab during the 20-min period preceding eight small X-ray flares are used to investigate the X-ray morphology of the preflare state of the active regions for any evidence of flare buildup. Not a single case is found where preflare brightening occurred in and only in the region which subsequently flared. For two events, no changes in the X-ray morphology of the preflare active region were noted up to within 2 min of the flare onset. Thus, no systematic evidence is found for a preflare buildup in any of these eight events.

Kahler, S. W.↗
NASA NTRS1976

ISIS-2 satellite imagery and auroral morphology

Auroral morphology is emphasized over auroral dynamics in a paper describing conspicuous auroral features picked up by the ISIS-2 scanning photometer. Results of improved programs designed to transform the data into a corrected geomagnetic coordinate frame and generate latitude profiles of auroral intensities at different magnetic local times are reported. The diffuse aurora and its relation to the morphology of discrete aurorae is given special attention.

Anger, C. D.↗
NASA NTRS1977

The morphological and statistical properties of solar X-ray events with long decay times

Photographic data from the S-054 X-ray telescope on Skylab has been used to study the morphological and statistical properties of a class of X-ray events with long decay times. The events were selected for analysis based on their Solrad 1-8 A flux signatures. These events are associated statistically with long-lived active regions, white-light coronal transients, and H alpha prominence activations. These X-ray events usually consist of an arcade of loops with a bright linear structure running along the arcade. The heights of the loops, their expansion velocities, their lifetimes, and morphological appearances all suggest that at least some of these events are the X-ray analog of the loop prominence systems observed in H alpha by Bruzek.

Kahler, S.↗
NASA NTRS1977

X-ray clusters of galaxies - Correlations with optical morphology and galaxy density

The entire sample of 37 X-ray clusters of galaxies detected by the Ariel 5 satellite at high latitudes is analyzed optically. Morphological types (for all clusters) and central galaxy densities (for all clusters with measured redshifts) are determined, and the positions, redshifts, and richness groups of the set of Southern Hemisphere X-ray clusters are estimated. The X-ray luminosity is found to be correlated with both cluster morphology and central galaxy density. The observed correlations are consistent with a thermal-bremsstrahlung model in which the hot intracluster gas density is proportional to the galaxy density, and the temperature is proportional to the galaxy velocity dispersion.

Bahcall, N. A.↗
NASA NTRS1977

Large-scale impact and explosion craters - Comparisons of morphological and structural analogs

Crater studies indicate now that there are a broad set of morphological and structural analogs which occur in both impact and explosion craters. A description is presented of impact and explosion analogs for three basic crater types, including bowl-shaped craters, flat-floored craters with central uplift, and flat-floored craters with multirings. A systematic documentation is provided of the more critical morphological and structural analogs common between large natural bowl-shaped impact and explosion craters, between central uplift impact and explosion craters, and between multiring impact and explosion craters. The data presented consist of a set of published and unpublished cratering studies assembled into a single ordered outline with each crater described in the same format and graphic style.

Roddy, D. J.↗
NASA NTRS1977

The effects of the pollutant, sodium cyanide, on the morphology and physiology of oedogonium cardiacum

OEDOGONIUM cardiacum exposed to varying concentrations of sodium cyanide for 15 day periods exhibited both morphological and physiological alterations. Organisms were exposed to the pollutant in concentrations of 1, 10, 25, 50, and 100 parts per million. Exposure period for organisms in each concentration was 15 days. As the concentration of the pollutant increased fragmentation also increased. Exposure also caused organisms to lose chlorophyll. The third morphological alteration was the incidence of rupture. Physiological effects altered by exposure included: reduced oxygen evolution, retardation of starch production and death. Death occurs when organisms are exposed to high concentrations over the total 15 day period.

Sparks, E.↗
NASA NTRS1978

NGC 2110 - An X-ray/radio galaxy with elliptical morphology

The detection of X-ray emission from NGC 2110, a narrow-emission-line galaxy of apparently elliptical morphology, is reported. A relatively hard 2-11-keV energy spectrum with an index of 0.1 + or - 0.3 is obtained, and the X-ray luminosity in this energy band is shown to be 1.2 x 10 to the 43rd erg/s for the redshift distance of 43 Mpc. Optical and radio observations are discussed which indicate a galactocentric redshift of approximately 0.0071, a resolved nonstellar optical nucleus about 4 arcsec in extent, Seyfert type 2 emission lines from the nucleus, and a nonthermal radio source located 3.0 arcsec from the position of the optical nucleus. No evidence is found for X-ray source variability in NGC 2110. It is suggested that the four to seven known X-ray-emitting high-excitation narrow-emission-line galaxies appear to be nearby examples of the Seyfert type 2 phenomenon and that the elliptical morphology of NGC 2110, if confirmed, may be unique among known Seyfert galaxies.

Bradt, H. V.↗
NASA NTRS1979

Morphological and functional manifestations of rat adrenal-cortex response to sodium bromide administration under hypodynamic stress

Functional and morphological manifestations of adrenal cortex response to hypodynamia (2-hr immobilization on an operating table) under the influence of bromine preparations were studied. The sodium bromide was administered intraperitoneally in 100, 250, and 500 mg/kg doses once and repeatedly during ten days. The adrenal gland was evaluated functionally by ascorbic acid and cholesterol content and morphologically by coloring it with hematoxylin-eosin and Sudans for lipid revealing at freezing. Results are displayed in two tables and microphotographs. They are summarized as follows: the bromine weakens the functional state of the adrenal cortex in intact rats, causing changes similar to those under stress. During immobilization combined with preliminary bromine administration, a less pronounced stress reaction is noticeable.

Kirichek, L. T.↗
NASA NTRS1979

Grooves on Phobos - Their distribution, morphology and possible origin

The global distribution, morphology, age, possible origin and significance of the long, linear depressions termed grooves on the surface of Phobos are discussed, based on Viking Orbiter data. The grooves, which consist of linear strings of coalesced and separate depressions in a loose regolith up to 100-200 m in depth, are observed to define the intersection of several sets of parallel planes with the surface of Phobos, with the widest and deepest grooves occurring just outside the rim of the 10-km crater, Stickney. The superposition of the grooves on older craters, crater density within the grooves and the intersections of groove sets suggest that the grooves are all of the same age, with their formation closely following that of Stickney. The evidence of groove morphology and distribution is used to attribute their formation to the enlargement of preexisting fractures or the formation of new fractures by the Stickney impact, causing the mobilization of the regolith along the fractures. The lack of observable grooves on Deimos is explained by the absence of a crater large enough to have severly fractured its surface.

Thomas, P.↗
NASA NTRS1980

Small impact craters in the lunar regolith - Their morphologies, relative ages, and rates of formation

The size frequency distributions, relative ages, and absolute age determination of lunar impact craters ranging in diameter from 1 to 100 m are discussed in relation to present-day and past impact rates. The size frequency distributions of craters produced by impacts on the lunar surface and of craters remaining after degradation with time and later impacts are examined, together with the steady state frequency curves for various crater morphologies. Relations between the relative ages of craters, their morphologies and their diameters are discussed, and the calibration of this kind of relationship with absolute crater ages by the location of individual craters with known absolute ages, diameters and frequency distribution statistics is considered. Estimates of present and past cratering rates based on crater size-frequency distributions are presented which suggest that the rate of impacting objects producing small lunar craters could have been constant over the last 100 million years.

Moore, H. J.↗