Post-asymptotic giant branch (post-AGB) stars are exquisite tracers of s-process nucleosynthesis, preserving the surface chemical signatures of their AGB evolution. The increasing chemical diversity observed among them challenges current nucleosynthesis models and motivates detailed case studies. In this study, we present a comprehensive abundance analysis of J003643.94$-$723722.1 (J003643), a single post-AGB star in the Small Magellanic Cloud (SMC). High-resolution UVES/VLT spectra analysed with E-iSpec reveal a C/O ratio of 16.21 and an $\textrm{[s/Fe]}$ = 2.09$\pm$0.20 dex. In this study, we also report the first direct detection of lead in a post-AGB star via the Pb II 5 608.853 Å line, with a derived $\textrm{[Pb/Fe]}$ = 3.18 dex. Comparison with a comprehensive and appropriate sample of post-AGB stars across the Galaxy, Large Magellanic Cloud (LMC) and SMC shows that J003643 has a relatively high C/O ratio, far exceeding the typical range of $\sim$1–3. J003643’s $\textrm{[C/Fe]}$ (1.33$\pm$0.14 dex) and $\textrm{[s/Fe]}$ (2.09$\pm$0.20 dex) are consistent with expectations from standard third dredge-up (TDU) enrichment. However, its $\textrm{[O/Fe]}$ (-0.08$\pm$0.20 dex) is significantly lower than that of the comparative sample with similar $\textrm{[C/Fe]}$ and $\textrm{[Fe/H]}$, which typically show $\textrm{[O/Fe]}$ between 0.5 and 1.0 dex. This relatively low $\textrm{[O/Fe]}$, along with an [$\alpha$/Fe]$\,\approx0$ dex of J003643, is consistent with the chemical evolution of the SMC at $\textrm{[Fe/H]}\,\approx-1$ dex, in contrast to the oxygen-enhanced Galactic and LMC trend at $\textrm{[Fe/H]}\,\approx-1$ dex. This indicates that J003643’s high C/O ratio primarily results from its intrinsic oxygen deficiency rather than from an unusually high carbon enhancement. To better understand the CNO, alpha, Fe-peak, and heavy element nucleosynthesis, we compared J003643’s abundance pattern with yields from three stellar evolutionary codes: ATON, MONASH, and FRUITY, the latter two incorporating post-processing nucleosynthesis. While these models reproduce the majority of elemental abundances, they significantly underpredict the Pb abundance, highlighting a persistent gap in our understanding of heavy element production in AGB stars. J003643 represents the second s-process enriched single post-AGB star known in the SMC, stressing the need for more such observations. Its photospheric chemistry reflects the growing chemical diversity among post-AGB stars and reinforces the complexity of AGB nucleosynthesis beyond current theoretical models.

Recently, there have been discussions about the shape of the heliopause. Some scientists question the classical form, which is close to a paraboloid. They suggest that the heliopause may have a two-jet collimated shape. While we disagree with this view of the heliopause shape, it seems likely that for stars with stronger stellar magnetic fields and those that are at rest or moving slowly through the interstellar medium, the astropause will have a two-jet collimated shape. This paper raises the question of the stability of the two-jet collimated astrosphere. Recent studies have noted the emergence of instability in the heliosheath near the axis of the heliospheric jets, linking this to the action of neutral hydrogen atoms. We note in this paper that astrospheric jets can become unstable in the presence of strong magnetic fields, even without the influence of atoms, which is unexpected. Furthermore, due to a feedback mechanism, astrospheric jets undergo self-oscillation. We investigated the development of this instability, the nature of the feedback mechanism, and the period of self-oscillation for different system parameters. Our findings provide valuable insights into the behaviour of these unique plasma structures, and they are another step towards studying the stability of two-jet collimated astrospheres.

We present a potential test of the origin of the $\gamma$-ray Galactic Centre Excess (GCE). We demonstrate how gravitational microlensing by stellar mass objects along the line of sight to the Galactic Bulge can distinguish between the possibility of extensive emission due to dark matter self-annihilation from more prosaic astrophysical sources, namely millisecond pulsars. Such an astrophysical origin would result in emission from a population of small, currently unresolved point-like sources – in contrast to the expected smoother emission resulting from dark matter annihilation. Given that the scale of gravitational microlensing, that is, the Einstein radius for stellar mass lenses, and hence, the degree of induced magnification, is sensitive to the size of the emitting region, such microlensing will induce time variability in the emission of astrophysical sources, whereas $\gamma$-ray emission from dark matter annihilation will effectively be immune to such influences. However, we find that detecting microlensing-induced variability requires significantly greater sensitivity than that of current or planned $\gamma$-ray detectors. For a small population of bright GCE sources, more than an order-of-magnitude increase in effective area over Fermi-LAT would be required, with events remaining extremely rare. For a large population of faint sources, events would occur multiple times a year, but would only be detectable with a four-order-of-magnitude improvement. Whilst microlensing might not be a definitive test of the origin of the GCE, in future observations, it may prove useful in determining the properties of any point-like source population.

We present a catalogue of 3 557 Double Radio sources associated with Active Galactic Nuclei (DRAGNs) from the First Pilot Survey of the Evolutionary Map of the Universe (EMU), observed at 944 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, covering 270 deg$^{2}$. We have extracted and identified each source by eye, tagged it with a morphological type and measured its parameters. The resulting catalogue will be used in subsequent papers to explore the properties of these sources, to train machine-learning algorithms for the detection of these sources in larger fields, and to compare with the results of Citizen Science projects, with the ultimate goal of understanding the physical processes that drive DRAGNs. Compared with earlier, lower sensitivity, catalogues, we find more diffuse structure and a plethora of more complex structures, ranging from wings of radio emission on the side of the jets, to types of object which have not been seen in earlier observations. As well as the well-known FR1 and FR2 sources, we find significant numbers of rare types of radio source such as Hybrid Morphology Radio Sources and one-sided jets, as well as a wide range of bent-tail and head-tail sources.

Second-generation circumbinary discs around evolved binary stars, such as post-Asymptotic Giant Branch (post-AGB) binaries, provide insights into poorly understood mechanisms of dust processing and disc evolution across diverse stellar environments. We present a multi-wavelength polarimetric survey of five evolved binary systems – AR Pup, HR 4049, HR 4226, U Mon, and V709 Car – using the Very Large Telescope SPHERE/ZIMPOL instrument. Post-AGB discs show significant polarimetric brightness at optical and near-IR wavelengths, often exceeding 1% of the system’s total intensity. We also measured a maximum fractional polarisation of the scattered light for AR Pup of ${\sim}$0.7 in the V-band and ${\sim}$0.55 in the I-band. To investigate wavelength-dependent polarisation, we combine the SPHERE/ZIMPOL dataset with results from previous SPHERE/IRDIS studies. This analysis reveals that post-AGB discs exhibit a grey to blue polarimetric colour in the optical and near-IR. Along with high fractional polarisation of the scattered light and polarised intensity distribution, these findings are consistent with a surface dust composition dominated by porous aggregates, reinforcing independent observational evidence for such grains in post-AGB circumbinary discs. We also find evidence of diverse disc geometries within the post-AGB sample, including arcs, asymmetries and significant variations in disc size across optical and near-IR wavelengths for some systems (U Mon, V709 Car). Combining our findings with existing multi-technique studies, we question the classification of two systems in our sample, HR 4226 and V709 Car, which were originally identified as post-AGB binaries based on their near-IR excess. On comparing post-AGB discs to circumstellar environments around AGB stars and YSOs, we found that post-AGB systems exhibit a higher degree of polarisation than single AGB stars and are comparable to the brightest protoplanetary discs around YSOs. Overall, our results reinforce the importance of polarimetric observations in probing dust properties and complex circumbinary structures. We also highlight the importance of combining multi-wavelength and multi-technique observations with advanced radiative-transfer modelling to differentiate between the various evolutionary pathways of circumbinary discs.

Until now, the study of unresolved main-sequence binary stars in globular clusters has been possible almost exclusively in their central regions with deep Hubble Space Telescope (HST) observations. We present the first detection of unresolved main-sequence binary stars in the outer field of 47 Tucanae using Rubin Observatory’s Data Preview 1 (DP1). Our analysis exploits deep i vs. $g-i$ colour–magnitude diagrams beyond the cluster’s half-light radius, reaching almost to the tidal radius. The high-quality photometry allowed to identify unresolved binaries with mass ratios q larger than 0.7. The derived binary fraction of $f_\mathrm{bin} (q\gt0.7)=0.016\pm0.005$ stands in contrast to the significantly lower values in the cluster innermost regions, as measured from HST photometry. This result provides new empirical input for testing physical processes that drive the formation and evolution of binary stars in globular clusters. It also demonstrates Rubin’s unique wide-field and high-precision photometric capabilities to address a broader range of outstanding questions in star cluster research. Future full data releases will enable to significantly expand the study of dense stellar systems across the Milky Way.

We present the first results from the COS-EDGES survey, targeting the kinematic connection between the interstellar medium and multi-phase circumgalactic medium (CGM) in nine isolated, near-edge-on galaxies at $z\sim0.2$, each probed along its major axis by a background quasar at impact parameters of $D=13-38$ kpc. Using VLT/UVES and HST/COS quasar spectra, we analyse Mgi, Mgii, Hi, Cii, Ciii, and Ovi absorption relative to galaxy rotation curves from Keck/LRIS and Magellan/MagE spectra. We find that low ionisation absorption for 8/9 galaxies lies below the halo escape velocity, indicating bound inflow or recycling gas, while 6/9 galaxies have high ionisation gas reaching above the halo escape velocity, suggesting some unbound material. We find that at lower $D/R_{\textrm{vir}}$ ($0.12\leq D/R_{\textrm{vir}} \leq0.20$), over 80% of absorption in all ions lies on the side of systemic velocity matching disk rotation, and the optical-depth–weighted median velocity ($v_{abs}$) is consistent with the peak rotation speed. At higher $D/R_{\textrm{vir}}$ ($0.21\leq D/R_{\textrm{vir}} \leq0.31$), the kinematics diverge by ionisation state: For the low ionisation gas, the amount of co-rotating absorption remains above 80%, yet $v_{abs}$ drops to roughly 60% of the galaxy rotation speed. For the high ionisation gas (Ovi), only 60% of the absorption is consistent with co-rotation and $v_{abs}$ drops to 20% of the galaxy rotation speed. Furthermore, the velocity widths, corresponding to 50% of the total optical depth ($\Delta v_{50}$) for low ionisation gas is up to 1.8 times larger in the inner halo than at larger radii, while for Ciii and Ovi $\Delta v_{50}$ remains unchanged with distance. The 90% optical-depth width ($\Delta v_{90}$) shows a modest decline with radius for low ionisation gas but remains constant Ciii and Ovi. At high $D/{R}_{\textrm{vir}}$, both $\Delta v_{50}$ and $\Delta v_{90}$ increase with ionisation potential. These results suggest a radially dependent CGM kinematic structure: the inner halo hosts cool, dynamically broad gas tightly coupled to disk rotation, whereas beyond $\gtrsim 0.2 R_{\textrm{vir}}$, particularly traced by Ovi and Hi, the CGM shows weaker rotational alignment and lower relative velocity dispersion. Therefore, low-ionisation gas likely traces extended co-rotating gas, inflows and/or recycled accretion, while high-ionisation gas reflects a mixture of co-rotating, lagging, discrete collisionally ionised structures and volume-filling warm halo, indicating a complex kinematic stratification of the multi-phase CGM.

We present an automated search method for radio transients on the minute timescale focused on the emerging long period transients (LPTs) in image-plane radio data. The method is tuned for use with the Murchison Widefield Array (MWA) and tested on archival observations from the GaLactic and Extragalactic All-Sky MWA Extended Survey (GLEAM-X) in the 70–300 MHz range. The images are formed from model-subtracted visibilities, before applying three filters to the time series of each pixel in an image, with each filter designed to be sensitive to a different transient behaviour. Due to the nature of radio interferometry and the refraction of the fluctuating ionosphere, the vast majority of candidates at this stage are artefacts which we identify and remove using a set of flagging measures. Of the 336 final candidates, 7 were genuine transients: 1 new LPT, 1 new pulsar, and 5 known pulsars. The performance of the method is analysed by injecting modelled transient pulses into a subset of the observations and applying the method to the result.

Quasi-periodic X-ray eruptions (QPEs) are a new class of repeating nuclear transient in which repeating X-ray flares are observed coming from the nuclei of generally low-mass galaxies. Here, we present a comprehensive summary of the radio properties of 12 bona-fide quasi-periodic eruption sources, including a mix of known tidal disruption events (TDEs) and AGN-like hosts. We include a combination of new dedicated radio observations and archival/previously published radio observations to compile a catalogue of radio observations of each source in the sample. We examine the overall radio properties of the sample and compare to the radio properties of known TDEs, given the apparent link between QPEs and TDEs. Overall we find compact, weak radio sources associated with 5/12 of the QPE sources and no signatures of strong AGN activity via a luminous radio jet. We find no radio variability on hour- to day-timescales corresponding to the X-ray QPEs, but do detect significant changes over year timescales in some sources, implying that the mechanism that produces the X-ray flares does not generate strong radio-emitting outflows. The compactness of the radio sources and lack of correlation between radio luminosity and SMBH mass is very unusual for AGN, but the radio spectra and luminosities are consistent with outflows produced by a recent TDE (or accretion event), in both the known TDE sources and the AGN-like sources in the sample.

Pulsars are rapidly rotating neutron stars that emit radiation across the electromagnetic spectrum, from radio to $\gamma$-rays. We use the rapid binary population synthesis suite COMPAS to model the Galactic population of canonical pulsars. We account for both radio and $\gamma$-ray selection effects, as well as the motion of pulsars in the Galactic potential due to natal kicks. We compare our models to the catalogues of pulsars detected in the radio, and those detected in $\gamma$-rays by Fermi, and find broad agreement with both populations. We reproduce the observed ratio of radio-loud to radio-quiet $\gamma$-ray pulsars. We further examine the possibility of low spin-down luminosity ($\dot{E}$) pulsars emitting weak, unpulsed $\gamma$-ray emission and attempt to match this with results from a recent $\gamma$-ray stacking survey of these pulsars. We confirm the correlation between the latitude of a pulsar and its $\dot{E}$ arises due to natal kicks imparted to pulsars at birth, assuming that all pulsars are born in the Galactic disk.

In this study, we investigate the chemical enrichment and structural evolution of the isolated elliptical relic galaxy Mrk1216 through X-ray observations. As a red-nugget relic, Mrk1216 provides a rare window into the early Universe, owing to its minimal interaction with the surrounding environment. Using data from the XMM-Newton telescope, we model the X-ray emission of its interstellar medium to derive radial temperature and abundance profiles. We find that the central region exhibits an elevated [Mg/Fe] ratio compared to typical early-type galaxies, consistent with a brief but intense star formation episode during its early assembly – a hallmark of relic systems. The nearly flat SNIa ratio profile ($R_{Ia} \sim 0.17$) extending to $\sim0.42R_{500}$ supports an early-enrichment scenario. These results highlight the importance of relic galaxies as benchmarks for studying early galaxy evolution and chemical enrichment. Future high-resolution missions and more advanced theoretical models incorporating more realistic initial mass functions are needed to fully assess their implications.

We present microsecond-resolution, coherently dedispersed, polarimetric measurements of 35 fast radio bursts (FRBs) detected during the Commensal Real-time ASKAP Fast Transients (CRAFT) incoherent sum (ICS) survey with the Australian Square Kilometre Array Pathfinder (ASKAP). We find a wide diversity of time–frequency morphology and polarisation properties broadly consistent with those of currently known non-repeating FRBs. The high S/N and fine time-resolution of our data however reveals a wealth of new information. Key results include (i) the distribution of scattering timescales, ${{{\unicode{x03C4}}_\textrm{obs}}}$, is limited purely by instrumental effects, with no downturn at high ${{{\unicode{x03C4}}_\textrm{obs}}}$ as expected from a log-normal distribution; (ii) for the 29 FRBs with known redshift, there is no detectable correlation between ${{{\unicode{x03C4}}_\textrm{obs}}}$ and dispersion measure (DM) fluctuations about the Macquart relation, in contrast to expectations from pulsar scattering–DM relations; (iii) all FRBs probably have multiple components, and at least a large fraction have variable PA, the identification of which is limited by scattering; (iv) at least half of all FRBs exhibit PA microstructure at 200 $\mu{}$s–200 ns timescales, with behaviour most closely resembling a sub-category of Crab main pulses; (v) that there is a break in the FRB circular polarisation distribution at Stokes $V \gtrsim 20$%, which is suggestive of a discrete sub-population.

High-resolution transmission spectroscopy has become a powerful tool for detecting atomic and ionic species in the atmospheres of ultra-hot Jupiters. In this study, we demonstrate for the first time that the Australian-built Veloce spectrograph on the 3.9-m Anglo-Australian Telescope can resolve atmospheric signatures from transiting exoplanets. We observed a single transit of the ultra-hot Jupiter WASP-189b – a favourable target given its extreme irradiation and bright host star – and applied the cross-correlation technique using standardised templates. We robustly detect ionised calcium ($\mathrm{Ca}^{+}$) and find evidence for hydrogen (H), sodium (Na), magnesium (Mg), neutral calcium (Ca), titanium (Ti), ionised titanium ($\mathrm{Ti}^{+}$), ionised iron ($\mathrm{Fe}^{+}$), neutral iron (Fe), and ionised strontium ($\mathrm{Sr}^{+}$). The strongest detection was achieved in the red arm of Veloce, consistent with expectations due to the prominent $\mathrm{Ca}^{+}$ triplet at wavelengths around 850–870 nm. Our results validate Veloce’s capability for high-resolution atmospheric studies, highlighting it as an accessible, flexible facility to complement larger international telescopes. If future observations stack multiple transits, Veloce has the potential to reveal atmospheric variability, phase-dependent spectral changes, and detailed chemical compositions of highly irradiated exoplanets.

The upcoming Square Kilometre Array Low Frequency (SKA-Low) interferometer will have the required sensitivity to detect the 21 cm line from neutral hydrogen during the Epoch of Reionisation (EoR). In preparation, we investigated the suitability of different fields for EoR science with the 21 cm line, using existing observations of candidate fields from the Murchison Widefield Array (MWA). Various image and calibration metrics were extracted from archival MWA observations centred on $z \sim 6.8$. We explore the usefulness of these metrics and compare their behaviour between different fields of interest. In addition, a theoretical approach to quantifying the impact of different fields on the power spectrum is also provided. Gain uncertainties were calculated based on the positions of the calibrators within the beam. These uncertainties were then propagated into visibilities to produce cylindrical power spectra for various fields. Using these metrics in combination with the power spectra, we confirm that EoR0 ($\text{R.A.} = 0\,\mathrm{deg}$, $\text{Dec} = {-}27.0\,\mathrm{deg}$) is an ideal EoR field and discuss the interesting behaviour of other fields.

We present a new method to calculate the polarised synchrotron emission of radio Active Galactic Nuclei (AGN) sources using magnetic field information from 3-dimensional relativistic magnetohydrodynamical (RMHD) simulations. Like its predecessor, which uses pressure as a proxy for the magnetic field, this method tracks the spatially resolved adiabatic and radiative loss processes using the method adapted from the Radio AGN in Semi-analytic Environments formalism. Lagrangian tracer particles in RMHD simulations carried out using the PLUTO code are used to track the fluid quantities of each ‘ensemble of electrons’ through time to calculate the radio emissivity ex situ. By using the magnetic field directly from simulations, the full set of linear Stokes parameters I, Q, and U can be calculated to study the synthetic radio polarisation of radio AGN sources. We apply this method to a suite of RMHD simulations to study their polarisation properties. The turbulent magnetic field present in radio lobes influences the emission, causing a complex clumpy structure that is visible at high resolution. Our synthetic polarisation properties are consistent with observations; we find that the fractional polarisation is highest (approximately 50%) at the lobe edges. We show that for the same source, the integrated and mean fractional polarisation depends on viewing angle to the source. At oblique viewing angles the behaviour of the integrated and mean fractional polarisation over time depends on the morphology of the jet cocoon. Using Faraday rotation measures, we reproduce known depolarisation effects such as the Laing-Garrington depolarisation asymmetry in jets angled to the line of sight. We show that the hotspots and hence the Fanaroff–Riley classification become less clear with our new, more accurate method.

This paper extends our previous study of the gyro-emission by energetic electrons in the magnetospheres of rapidly rotating, magnetic massive stars, through a quantitative analysis of the role of cooling by Coulomb collisions with thermal electrons from stellar wind material trapped within the centrifugal magnetosphere (CM). For the standard, simple CM model of a dipole field with aligned magnetic and rotational axes, we show that both gyro-cooling along magnetic loops and Coulomb cooling in the CM layer have nearly the same dependence on the magnitude and radial variation of magnetic field, implying then that their ratio is a global parameter that is largely independent of the field. Analytic analysis shows that, for electrons introduced near the CM layer around a magnetic loop apex, collisional cooling is more important for electrons with high pitch angle, while more field-aligned electrons cool by gyro-emission near their mirror point close to the loop base. Numerical models that assume a gyrotropic initial deposition with a gaussian distribution in both radius and loop co-latitude show the residual gyro-emission is generally strongest near the loop base, with highly relativistic electrons suffering much lower collisional losses than lower-energy electrons that are only mildly relativistic. Even for cases in which the energy deposition is narrowly concentrated near the loop apex, the computed residual emission shows a surprisingly broad distribution with magnetic field strength, suggesting that associated observed radio spectra should generally have a similarly broad frequency distribution. Finally, we briefly discuss the potential applicability of this formalism to magnetic ultracool dwarfs (UCDs), for which Very Long Baseline Interferometry (VLBI) observations indicate incoherent radio emission to be concentrated around the magnetic equator, in contrast to our predictions here for magnetic hot stars. We suggest that this difference could be attributed to UCDs having either a lower ambient density of thermal electrons, or more highly relativistic non-thermal electrons, both of which would reduce the relative importance of the collisional cooling explored here.

We present the third data release for the Galactic and Extragalactic All-Sky Murchison Widefield Array eXtended (GLEAM-X) survey, covering $\approx 3\,800$ deg$^2$ of the southern Galactic Plane (GP) with ${233}^{\circ} \lt l \lt {44}^{\circ}$ and $|b| \lt {11}^{\circ}$ across a frequency range of 72–231 MHz divided into 20 sub-bands. GLEAM-X observations were taken using the ‘extended’ Phase-ii configuration of the Murchison Widefield Array (MWA), which features baselines ranging from approximately 12 m to 5 km. This configuration limits sensitivity to the diffuse structure of the GP, with an angular resolution range of about $45^{''}$ to $2^{'}$. To achieve lower noise levels while being sensitive to a wide range of spatial scales ($45^{''} - {15}^{\circ}$), we combined these observations with the previous Galactic and Extragalactic All-Sky Murchison Widefield Array (GLEAM) survey. For the area covered, we provide images spanning the whole frequency range. A wide-band image over 170–231 MHz, with RMS noise of $\approx\;$3–6 mJy beam$^{-1}$ and source position accuracy within 1 arcsec, is then used to perform source-finding, which yields 98 207 elements measured across $20 \times 7.68$ MHz frequency bands. The catalogue is 90$\%$ complete at 50 mJy within ${233}^{\circ} \lt l \lt {324}^{\circ}$ and at 125 mJy in ${290}^{\circ} \lt l \lt {44}^{\circ}$, while it is $99.3\%$ reliable overall. All the images and the catalogue are available online for download.

This paper reports the discovery and follow-up of four candidate redback spider pulsars: GPM J1723$-33$, GPM J1734$-28$, GPM J1752$-30$, and GPM J1815$-14$, discovered with the Murchison Widefield Array (MWA) from an imaging survey of the Galactic Plane. These sources are considered to be redback candidates based on their eclipsing variability, steep negative spectral indices, and potential Fermi $\gamma$-ray associations, with GPM J1723$-33$ and GPM J1815$-14$ lying within a Fermi 95$\%$ error ellipse. Follow-up pulsation searches with MeerKAT confirmed pulsations from GPM J1723$-33$, while the non-detections of the other three are likely due to scattering by material ablated from their companion stars. We identify possible orbital periods by applying folding algorithms to the light curves and determine that all sources have short orbital periods ($\lt$24 h), consistent with redback spider systems. Following up on the sources at multiple radio frequencies revealed that the sources exhibit frequency-dependent eclipses, with longer eclipses observed at lower frequencies. We place broad constraints on the eclipse medium, ruling out induced Compton scattering and cyclotron absorption. Three sources are spatially consistent with optical sources in the Dark Energy Camera Plane Survey imaging, which may contain the optical counterparts. Each field is affected by strong dust extinction, and follow-up with large telescopes is needed to identify the true counterparts. Identifying potential radio counterparts to four previously unassociated Fermi sources brings us closer to understanding the origin of the unexplained $\gamma$-ray excess in the Galactic Centre.

This study examines the resolved Kennicutt-Schmidt (rK-S) relation, defined as the connection between the star formation rate surface density ($\Sigma_{SFR}$) and the molecular gas mass surface density ($\Sigma_{H_2}$) in the high-density central regions of three nearby barred spiral galaxies hosting AGN: NGC 1365, NGC 1433, and NGC 1566. Utilising high-resolution archival data from AstroSat/UVIT for UV imaging and Atacama Large Millimetere/submillimetre Array (ALMA) for CO(2-1) molecular gas mapping, we explore recent star formation and gas distribution with a spatial resolution of $\sim$120–132 pc. Our findings reveal a sublinear rK-S law, with slopes ranging from $\sim$0.17 to $\sim$0.71. Notably, NGC 1566 exhibits a robust rK-S relation consistent with previous studies, while NGC 1365 and NGC 1433 exhibit weaker correlations. These differences are likely due to the smaller number of identified star-forming regions in these galaxies compared to NGC 1566, as well as the central molecular gas concentrations and varying star formation activity in their bars and nuclear regions. These results also support the idea that the rK-S relation deviates from linearity in extreme environments, such as starburst galaxies and galactic centres. Additionally, we find a generally low median star formation efficiency (SFE) within the bars of these galaxies, suggesting that while bars may drive nuclear starbursts and contribute to bulge growth, they do not significantly increase SFE. Furthermore, a negative correlation between SFE and $\Sigma_{H_2}$ is observed across the sample, both within and outside the bar regions, suggesting that higher $\Sigma_{H_2}$ may lead to lower SFE in the central regions of these galaxies. Our findings highlight that $\Sigma_{H_2}$ plays a primary role in shaping the observed trends in SFE, rather than the presence of a bar itself.

High-redshift protoclusters are crucial for understanding the formation of galaxy clusters and the evolution of galaxies in dense environments. The James Webb Space Telescope (JWST), with its unprecedented near-infrared sensitivity, enables the first exploration of protoclusters beyond $ z \gt 10 $. Among JWST surveys, COSMOS-Web Data Release 0.5 offers the largest area ($\sim 0.27$ deg$^2$), making it an optimal field for protocluster searches. In this study, we searched for protoclusters at $ z \sim 9-10 $ using 366 F115W dropout galaxies. We evaluated the reliability of our photometric redshift by validation tests with the JADES DR3 spectroscopic sample, obtaining the likelihood of falsely identifying interlopers as $\sim25\%$. Overdensities ($\delta$) are computed by weighting galaxy positions with their photometric redshift probability density functions, using a 2.5 cMpc aperture and a redshift slice of $\pm 0.5$. We selected the most promising core galaxies of protocluster candidate galaxies with an overdensity greater than the 95th percentile of the distribution of 366 F115W dropout galaxies. The member galaxies are then linked within an angular separation of 7.5 cMpc to the core galaxies, finding seven protocluster candidates. These seven protocluster candidates have inferred halo masses of $ M_{\text{halo}} \sim 10^{11}\,{\rm M}_{\odot} $. The detection of such overdensities at these redshifts provides a critical test for current cosmological simulations. However, confirming these candidates and distinguishing them from low-redshift dusty star-forming galaxies or Balmer-break galaxies will require follow-up near-infrared spectroscopic observations.