arXiv subjects

Manish Kataria

Publications and source records attributed to Manish Kataria.

8 recordsLinked to original sources

arXiv2026

The kinematics of tadpole galaxies at intermediate redshift $z \sim 0.4 - 1.5$

Galaxy morphology and kinematics encode complementary information about the assembly history of galaxies, but the extent to which they evolve in tandem remains unclear. Tadpole galaxies, characterized by their distinct head-tail morphology and pronounced asymmetry, provide an ideal laboratory for investigating whether strongly asymmetric galaxies can exhibit ordered galaxy-scale kinematics. In this work, we present a detailed analysis of the ionized-gas kinematics of 20 morphologically selected tadpole galaxies at redshifts $z=0.4 - 1.5$ in the Hubble Ultra Deep Field, using deep VLT/MUSE spectroscopy together with HST and JWST imaging. In 13 out of 20 galaxies, the 2D velocity maps derived from the MUSE [O\,{\sc ii}] $\lambda\lambda3726,3729$ emission show evidence for ordered motion, characterized by moderate velocity gradients along the kinematic major axis, while the remaining systems show no clear evidence for galaxy-scale ordered kinematics. In 16 galaxies, the [O\,{\sc ii}] and rest-frame optical emission, probed by HST/F775W, have spatially coincident centroids, with projected offsets of $<2$~kpc. The morpho-kinematic position angles are also generally well aligned, with a median misalignment of $\Delta{\rm PA}\sim12^{\circ}$. Despite the strongly asymmetric tadpole morphologies, these results indicate that a substantial fraction of these systems retain coherent galaxy-scale gaseous kinematics, suggesting that morphological asymmetry need not imply a globally disordered dynamical state. Together, our analyses suggest that morphological and kinematic settlement does not occur simultaneously and these tadpole galaxies might represent a transient evolutionary phase towards the combined morpho-kinematic settlement process.

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arXiv2026

Ly$\rm \alpha$ halos and UV continuum morphologies of Tadpole Galaxies at $z> 3$

Tadpole and clump-chain galaxies are a morphologically distinct population among high-redshift star-forming galaxies whose disturbed structures may influence the escape and propagation of Ly$\alpha$ photons. We investigate the Ly$\alpha$ and UV continuum properties of 12 tadpole galaxies in the redshift range of z $\sim$ 3 -- 5.5 identified in the Hubble Ultra Deep Field (HUDF) using deep MUSE observations. Accounting for their elongated morphologies, we construct surface brightness profiles and characterize the spatial extent of their Ly$\alpha$ emission. Extended Ly$\alpha$ halos are detected in 10 of the 12 galaxies, demonstrating that diffuse Ly$\alpha$ emission is common among tadpole systems. Approximately 40\% of the sample exhibits double-peaked Ly$\alpha$ profiles. While the effective radii ($\rm R_{e}$) of the Ly$\rm \alpha$ emission generally follow the spatial extent of the UV continuum, the Ly$ \rm \alpha$ halos are typically more symmetric and often exhibit spatial offsets from the stellar component. Some galaxies also display asymmetric and outflow-like Ly$\rm \alpha$ structures suggestive of anisotropic escape and complex radiative transfer effects. Together, these results suggest that the disturbed morphologies of tadpole galaxies may influence the transport of Ly$\rm \alpha$ photons and contribute to the formation of extended Ly$\rm \alpha$ halos in the circumgalactic medium.

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arXiv2025

Chemically primitive dwarf accretion reignites the inner disk assembly of Malin 1

We present a detailed kinematic and stellar population analysis of the inner disk of Malin 1, a giant low surface brightness (GLSB) galaxy with a prominent SB0-type central morphology. AstroSat far-UV imaging reveals clumpy emission features indicating recent star formation. Using MUSE integral field spectroscopy, we identify four star-forming complexes (SFCs) within the inner 10 kpc, each associated with localized ionized gas emission in distinct H$\alpha$ velocity channels. Two of the SFCs, including a far-UV clump, appear on the blue-shifted side ($V_{H\alpha}=-230~\mathrm{kms^{-1}}$), while the other two are redshifted. The far-UV clump shows a strong velocity offset ($\sim150~\mathrm{kms^{-1}}$) and high gas dispersion ($\sim250~\mathrm{kms^{-1}}$), indicating that it is kinematically decoupled from the rotating disk. The spatial and velocity isolation of these features in the channel map confirms they do not follow regular disk rotation. The far-UV clump hosts young (250-500 Myr), extremely metal-poor ([M/H]$\simeq$ -1.69) and $\alpha$-enriched ($[\alpha/Fe] \sim 0.5$) stellar populations, sharply contrasting with the surrounding super-solar gas-phase metallicity. The young stellar populations in each SFC are chemically distinct (similar to the far-UV clump) from the enriched central ISM, indicating rapid, local star formation from primitive gas before efficient mixing with the enriched ISM. Their spatial and velocity segregation, age synchronicity, and chemical homogeneity suggest an origin of gas delivered by a disrupted, gas-rich dwarf on a high-inclination (off-plane) orbit. These results suggest that the central HSB within $\rm \sim 9^{\prime\prime} (14\ kpc)$ radius component of Malin 1 has grown through discrete, externally driven accretion, contributing to its complex, hybrid disk morphology.

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arXiv2025

Clump-fed black hole growth in the first billion years of the universe

Understanding how supermassive black holes (SMBHs) form in the early universe is one of the most challenging problems in astrophysics. Their high abundance in the first billion years, as observed by the James Webb Space Telescope, hints towards black hole seeds that accrete mass rapidly. The origin of this accreted mass is not known. Here, we consider a billion solar mass clumpy galaxy at z=5.48 with a 30 million solar mass black hole in the center. We show that the clumps should migrate to the central region because of torques from dynamical friction with the halo, funneling in at least 14 solar masses per year. This is fast enough to grow the observed SMBH, with only 1% of the accreted mass getting in and the rest going to a bulge. Clump-fed accretion could explain most young SMBHs because young galaxies are highly irregular with massive star-forming clumps.

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arXiv2025

Chemical signature reveals co-spatial dwarf satellite of an edge-on disc galaxy with MUSE

Integral field unit (IFU) spectroscopic observations of resolved galaxies provide an optimal experimental setting for determination of stellar population properties, in particular - age, metallicity and $\alpha$-enhancement, which are key to understanding evolution of galaxies across diverse physical environments. We determine these properties for the edge-on disc galaxy IC 1553, through stellar population models fitted to MUSE IFU observations. From our determined spatial distributions of metallicity and [$\alpha$/Fe], we serendipitiously identify the unique chemical signature of a dwarf galaxy that is co-spatial with the luminous disc of IC 1553. The dwarf galaxy is characterized by the presence of higher [$\alpha$/Fe] and metal-poor stellar populations relative to the disc of IC 1553. The identified dwarf is dynamically cold from its determined kinematics, consistent with being a satellite of IC 1553. From modeling the Spitzer IRAC 3.6 $\mu m$ image of IC 1553, we confirmed the presence of the dwarf galaxy and calculated its stellar mass to be $\sim1.28\times 10^{9} \rm~M_{\odot}$. This is the first such identification of a dwarf galaxy from its unique chemical signature in such integrated light IFU observations, even though its hidden by the luminous body of its massive host.

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arXiv2024

AstroSat UV Deep Field South -- I. Far and Near-ultraviolet Source Catalog of the GOODS South region

We present the AstroSat UV Deep Field South (AUDFs), an imaging survey using the wide-field Ultraviolet Imaging Telescope on board AstroSat. AUDFs covers $\sim 236$ arcmin$^{2}$ of the sky area, including the Great Observatories Origins Deep Survey (GOODS) South field in F154W and N242W filters. The deep and shallow parts of AUDFs have exposure time $\sim 62000$ and $\sim31000$ sec respectively, in the F154W filter, while in the N242W filter, they are $\sim 64000$ and $\sim34000$ sec. These observations reached a $3\sigma$ depth of 27.2 and 27.7 AB mag with a $50\%$ completeness limit of 27 and 27.6 AB mag in the F154W and N242W filters, respectively. With the acquired depth, AUDFs is the deepest far and near-UV imaging data covering the largest area known to date at 1.2" - 1.6" spatial resolution. Two primary catalogs were constructed for the F154W and N242W filters, each containing 13495 and 19374 sources brighter than the 3$\sigma$ detection limit, respectively. Our galaxy counts power-law slope $\sim0.43$~dex~mag$^{-1}$ in the N242W filter matches well with HST/WFC3/UVIS observations. A wide range of extra-galactic science can be achieved with this unique data, such as providing a sample of galaxies emitting ionizing photons in the redshift range $z \sim 1 - 3$ and beyond; constraining the UV luminosity function, investigating the extended-UV (XUV) emission around star-forming galaxies and UV morphologies for $z < 1$. The UV catalog will enhance the legacy value of the existing optical/IR imaging and spectroscopic observations from ground and space-based telescopes on the GOODS South field.

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arXiv2024

The leakage of Lyman-continuum photons from a major merger at $z\sim1$

We report the detection of Lyman-continuum (LyC) photons from a massive interacting system at $z=1.097$ in the Hubble Ultra Deep Field. The LyC detection is made in the far-ultraviolet F154W band of the UVIT telescope onboard AstroSat. Both JWST and HST imaging of the system reveal signs that it is a likely merger. In particular, high-resolution imaging in the JWST bands reveals an infrared luminous object within the system that is faint in the bluer HST bands. The ionized-gas kinematics from the MUSE-UDF data supports the merger hypothesis. We estimate that the entire system is leaking more than $8 \%$ of its ionizing photons to the intergalactic medium. The SED-derived stellar masses of the two components indicate that this is a major merger with a mass ratio of ${1.13 \pm 0.37}$. This detection hints at the potential contribution of massive interacting systems at higher redshifts, when major mergers were more frequent, to the ionizing budget of the universe.

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arXiv2024

Understanding stellar populations in thin & thick discs of edge-on galaxies with MUSE -- I. The case of the reignited S0 galaxy ESO 544-27

Edge-on galaxies act as the best laboratories to understand the origin of thin and thick discs in galaxies. Measurement of spatially resolved stellar population properties in such galaxies, particularly age, metallicity and [$α$/Fe], are crucial to understanding the formation and evolution of disc galaxies. Such measurements are made possible from stellar population model fits to deep integral field spectroscopic (IFU) observations of resolved galaxies. We utilise archival MUSE IFU observations of the edge-on galaxy ESO 544-27 to uncover the formation history of its thin and thick discs through its stellar populations. We find the thin disc of the galaxy is dominated by an old ($>9$ Gyr) low [$α$/Fe] metal-rich stellar population. Its outer thick disc is dominated by an old ($>9$ Gyr) high [$α$/Fe] metal-rich component that should have formed with higher star-formation efficiency than the Milky Way thick disc. We thus find [$α$/Fe] dichotomy in ESO 544-27 with its thin and thick discs dominated by low and high [$α$/Fe] stellar populations respectively. However, we also find a metal-rich younger ($<2$ Gyr old) stellar population in ESO 544-27. The galaxy was nearly quenched until its star-formation was reignited recently first in the outer and inner thick disc ($\sim$1 Gyr ago) and then in the thin disc ($\sim$600 Myr ago). We thus find that both the low [$α$/Fe] thin and high [$α$/Fe] thick discs of ESO 544-27 are inhabited primarily by similarly old metal-rich stellar populations, a contrast to that of other galaxies with known thin and thick disc stellar population properties.

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