A z=4.9 LAE protocluster exhibits 40% larger rest-optical sizes than field LAEs with no UV difference, indicating wavelength-dependent environmental influences on galaxy structure.
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21 Pith papers cite this work, alongside 2,403 external citations. Polarity classification is still indexing.
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abstract
We present a two-dimensional (2-D) fitting algorithm (GALFIT) designed to extract structural components from galaxy images, with emphasis on closely modeling light profiles of spatially well-resolved, nearby galaxies observed with the Hubble Space Telescope. Our algorithm improves on previous techniques in two areas, by being able to simultaneously fit a galaxy with an arbitrary number of components, and with optimization in computation speed, suited for working on large galaxy images. We use 2-D models such as the ``Nuker'' law, the Sersic (de Vaucouleurs) profile, an exponential disk, and Gaussian or Moffat functions. The azimuthal shapes are generalized ellipses that can fit disky and boxy components. Many galaxies with complex isophotes, ellipticity changes, and position-angle twists can be modeled accurately in 2-D. When examined in detail, we find that even simple-looking galaxies generally require at least three components to be modeled accurately, rather than the one or two components more often employed. We illustrate this by way of 7 case studies, which include regular and barred spiral galaxies, highly disky lenticular galaxies, and elliptical galaxies displaying various levels of complexities. A useful extension of this algorithm is to accurately extract nuclear point sources in galaxies. We compare 2-D and 1-D extraction techniques on simulated images of galaxies having nuclear slopes with different degrees of cuspiness, and we then illustrate the application of the program to several examples of nearby galaxies with weak nuclei.
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representative citing papers
A new catalogue of bar lengths and widths from HST images of 8230 galaxies shows bars are about 13% weaker at higher redshift, with longer bars in higher-mass quiescent galaxies and trends consistent with slow quenching.
Clumps in high-redshift spiral galaxies are smaller than commonly reported, spatially concentrated toward spiral arms, smaller but brighter inside arms than between them, with similar colors, suggesting arms stimulate clump formation but do not alter their star formation properties.
Corrected empirical limits show the most massive galaxies never exceed the theoretical baryonic maximum of 0.16 times halo virial mass, keeping observations consistent with LambdaCDM at all redshifts.
Multi-phase observations of NGC 1427A indicate tidal torquing from a dwarf fly-by has pre-conditioned its gas for ram-pressure stripping by the Fornax intracluster medium, placing the galaxy at the onset of environmental quenching with a declining star formation rate.
UV-bright companions to Little Red Dots provide Lyman-Werner fluxes of J21 ~ 10^2.5-10^5 that can suppress H2 cooling and enable direct collapse to massive black holes.
Morphological metrics in galaxy images suffer systematic biases from resolution, depth, and noise that can be quantified and corrected empirically, with new metrics proposed to reduce those effects.
A Hubble-like sequence of galaxy morphologies exists by redshift 4, with low-mass galaxies as persistent star-forming disks and massive galaxies following either stable disk or rapid compaction-quenching paths.
ATTILA tool identifies 24 new ultra-diffuse galaxies in Hydra I, doubling the known population to 48, plus 92 additional low surface brightness galaxies, while recovering over 80% of previously known ones.
A z=4.0148 galaxy shows clumpy ring morphology consistent with either a collisional ring or strong lensing by a foreground galaxy at z~1.7.
Star-forming galaxies show a transition from negative to positive sSFR radial gradients around z~2, implying a change from outside-in to inside-out growth.
Local compact AGN-hosting dwarf galaxies with V-shaped SEDs are more evolved than high-redshift Little Red Dots, indicating distinct formation pathways.
Multi-epoch spectroscopy of UNAM-KIAS 613 shows transient double-peaked broad Hα emission interpreted as a one-time bipolar outflow in an isolated low-luminosity AGN with Eddington ratio ~0.03-0.04.
JWST finds infrared counterparts for nearly all micro-Jy radio sources, with star formation explaining the radio output in roughly 79% of cases after accounting for non-linear luminosity relations.
A single galaxy cluster lenses two quasars (one Type I at z=1.524, one dust-obscured Type II at z=1.939) into four images each, yielding a projected mass of ~3.3e14 solar masses within 500 kpc and time delays of hundreds to over 1000 days.
Host galaxy analysis rules out a globular cluster origin for the GRB 230307A kilonova and shows a disk-formed BNS merger with natal kicks can reach the observed offset in only 0.1% of population-synthesis realizations.
NIRCam-selected AGN hosts split into a 'bridge' group with moderate-to-low SFRs and a 'branch' group above the SFMS with SFR rising with AGN fraction; both populations show recent transitions between star formation and quiescence.
Mock CSST images yield 95% completeness limits of 26.3-28.5 mag for point sources and 24.4-27.1 mag for galaxies, with fainter objects showing systematic overestimates in magnitude, size, and surface brightness and underestimates in Sersic index and axis ratio.
New SBF distance confirms NGC5846_UDG1 lies in the NGC 5846 group and reconciles prior GC counts to ~50 members, supporting a massive dark matter halo.
Optimizes ImageNet-pretrained AlexNet, UMAP, and a bagging multi-cluster voting scheme with K-means, Birch and Agg for unsupervised galaxy morphology classification, reporting improved stability and consistency with galaxy evolution expectations.
citing papers explorer
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Discovery of a $z\simeq 4.9$ Lyman-$\alpha$ Emitter Protocluster: Wavelength-Dependent Environmental Effects on Galaxy Structure
A z=4.9 LAE protocluster exhibits 40% larger rest-optical sizes than field LAEs with no UV difference, indicating wavelength-dependent environmental influences on galaxy structure.
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Galaxy Zoo Bar Lengths: A Catalogue of Measurements from Hubble Space Telescope Images and the Evolution of Galactic Bar Structure at z < 1
A new catalogue of bar lengths and widths from HST images of 8230 galaxies shows bars are about 13% weaker at higher redshift, with longer bars in higher-mass quiescent galaxies and trends consistent with slow quenching.
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Clumps in spiral galaxies at $z \lesssim 3$: Disentangling two spatial modes of star formation
Clumps in high-redshift spiral galaxies are smaller than commonly reported, spatially concentrated toward spiral arms, smaller but brighter inside arms than between them, with similar colors, suggesting arms stimulate clump formation but do not alter their star formation properties.
-
Empirical estimates of how massive galaxies can be in {\Lambda}CDM
Corrected empirical limits show the most massive galaxies never exceed the theoretical baryonic maximum of 0.16 times halo virial mass, keeping observations consistent with LambdaCDM at all redshifts.
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Tidal pre-conditioning and ram-pressure stripping in NGC 1427A. Deep VLT/MUSE spectroscopy and FUV-to-radio observations trace a Fornax Cluster dwarf in transformation
Multi-phase observations of NGC 1427A indicate tidal torquing from a dwarf fly-by has pre-conditioned its gas for ram-pressure stripping by the Fornax intracluster medium, placing the galaxy at the onset of environmental quenching with a declining star formation rate.
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Connecting the Dots: UV-Bright Companions of Little Red Dots as Lyman-Werner Sources Enabling Direct Collapse Black Hole Formation
UV-bright companions to Little Red Dots provide Lyman-Werner fluxes of J21 ~ 10^2.5-10^5 that can suppress H2 cooling and enable direct collapse to massive black holes.
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statmorph-lsst: Quantifying and correcting morphological biases in galaxy surveys
Morphological metrics in galaxy images suffer systematic biases from resolution, depth, and noise that can be quantified and corrected empirically, with new metrics proposed to reduce those effects.
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The Hubble sequence in JWST CEERS from unbiased galaxy morphologies
A Hubble-like sequence of galaxy morphologies exists by redshift 4, with low-mass galaxies as persistent star-forming disks and massive galaxies following either stable disk or rapid compaction-quenching paths.
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Advancing the detection of low surface brightness galaxies. I. ATTILA: multi-tAsking deTecTIon tool for Lsb gAlaxies
ATTILA tool identifies 24 new ultra-diffuse galaxies in Hydra I, doubling the known population to 48, plus 92 additional low surface brightness galaxies, while recovering over 80% of previously known ones.
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JWST's PEARLS: A clumpy ring galaxy at $z = 4.0148$
A z=4.0148 galaxy shows clumpy ring morphology consistent with either a collisional ring or strong lensing by a foreground galaxy at z~1.7.
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Transition from Outside-in to Inside-Out at $z\sim 2$: Evidence from Radial Profiles of Specific Star Formation Rate based on JWST/HST
Star-forming galaxies show a transition from negative to positive sSFR radial gradients around z~2, implying a change from outside-in to inside-out growth.
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Compact, AGN-hosting Dwarf Galaxies with "Little Red Dots"-like SEDs in the Local Universe
Local compact AGN-hosting dwarf galaxies with V-shaped SEDs are more evolved than high-redshift Little Red Dots, indicating distinct formation pathways.
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Spectral Evolution and Transient Broad-Line Features in the Isolated AGN UNAM-KIAS 613
Multi-epoch spectroscopy of UNAM-KIAS 613 shows transient double-peaked broad Hα emission interpreted as a one-time bipolar outflow in an isolated low-luminosity AGN with Eddington ratio ~0.03-0.04.
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PEARLS: JWST Counterparts of Micro-Jy Radio Sources in the NEP Time Domain Field. II. All Four Spokes
JWST finds infrared counterparts for nearly all micro-Jy radio sources, with star formation explaining the radio output in roughly 79% of cases after accounting for non-linear luminosity relations.
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COOL-LAMPS IX: A Rare Duo of Quasars Each Lensed by a Single Massive Galaxy Cluster
A single galaxy cluster lenses two quasars (one Type I at z=1.524, one dust-obscured Type II at z=1.939) into four images each, yielding a projected mass of ~3.3e14 solar masses within 500 kpc and time delays of hundreds to over 1000 days.
-
Probing the origin of the kilonova candidate GRB 230307A: analysis of host galaxy and offset
Host galaxy analysis rules out a globular cluster origin for the GRB 230307A kilonova and shows a disk-formed BNS merger with natal kicks can reach the observed offset in only 0.1% of population-synthesis realizations.
-
PEARLS: Two Distinct Populations of AGN Hosts Moving Between Star Formation and Quiescence
NIRCam-selected AGN hosts split into a 'bridge' group with moderate-to-low SFRs and a 'branch' group above the SFMS with SFR rising with AGN fraction; both populations show recent transitions between star formation and quiescence.
-
CSST Preparations: Galaxy Completeness and S\'ersic Profile Fitting across the Wide, Deep, and Extreme Fields
Mock CSST images yield 95% completeness limits of 26.3-28.5 mag for point sources and 24.4-27.1 mag for galaxies, with fainter objects showing systematic overestimates in magnitude, size, and surface brightness and underestimates in Sersic index and axis ratio.
-
Revisiting the distance and the globular cluster system of the remarkable galaxy UDG1 in the NGC 5846 group
New SBF distance confirms NGC5846_UDG1 lies in the NGC 5846 group and reconciles prior GC counts to ~50 members, supporting a massive dark matter halo.
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Robustness Analysis of USmorph: II. Optimizing Feature Extraction, Dimensionality Reduction, and Clustering for Unsupervised Galaxy Morphology Classification
Optimizes ImageNet-pretrained AlexNet, UMAP, and a bagging multi-cluster voting scheme with K-means, Birch and Agg for unsupervised galaxy morphology classification, reporting improved stability and consistency with galaxy evolution expectations.
- MSA-3D: Connecting the Chemical and Kinematic Structures of Galaxies at $z \sim 1$