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Ultraluminous X-ray sources (ULXs) were once largely believed to be powered by super-Eddington accretion onto stellar-mass black holes, although in some rare cases, ULXs also serve as potential candidates for (sub-Eddington) intermediate mass black holes. However, a total of eight ULXs have now been confirmed to be powered by neutron stars, thanks to observed pulsations, and may act as contaminants for radio/X-ray selection of intermediate mass black holes. Here we present the first comprehensive radio study of seven known neutron star ULXs using new and archival data from the Karl G. Jansky Very Large Array and the Australia Telescope Compact Array, combined with the literature. Across this sample there is only one confident radio detection, from the Galactic neutron star ULX Swift J0243.6+6124. The other six objects in our sample are extragalactic, and only one has coincident radio emission, which we conclude is most likely contamination from a background HII region. We conclude that with current facilities, neutron star ULXs do not produce significant enough radio emission to cause them to be misidentified as radio/X-ray selected intermediate mass black hole candidates. Thus, if background star formation has been properly considered, the current study indicates that a ULX with a compact radio counterpart is not likely to be a neutron star., Comment: 14 pages, 2 figures, accepted to ApJ

In this paper, we give inductive sum formulas to calculate the number of diagonally symmetric, and diagonally \& anti-diagonally symmetric domino tilings of Aztec Diamonds. As a byproduct, we also find such a formula for the unrestricted case as well. Our proofs rely on a new technique for counting the number of perfect matchings of graphs, proposed by the authors recently., Comment: 19 pages, 11 figures, 3 tables, comments are welcome

The 2-adic valuation of an integer n which is the exponent of the highest power of 2 that divides n. In this paper, we give representations of certain restricted partition functions in terms of 2-adic valuation.

The number of points on a certain one parameter family of algebraic surface over a finite field $\F_p$ can be expressed as $p^2+A_p(\lambda),$ where $A_p(\lambda)$ is a character sum and $\lambda$ is an element of the finite field $\F_p.$ In this paper, we study the distribution of the term $A_p(\lambda)$ as the surface varies over a large family of algebraic surfaces of fixed genus and growing $p.$ The power moments of $A_p$'s are weighted sums of Catalan numbers. As a consequence of these results, we obtain limiting distributions of certain families of hypergeometric functions over large finite fields.

Recently, Andrews and El Bachraoui (2024) proved three very interesting $q$-series identities, from which three simple looking identities involving certain restricted partitions into distinct even parts and $4$-regular partitions follow. In this short note, we give combinatorial proofs of these identities. We also prove the counterpart identities for the restricted partitions into distinct odd parts., Comment: 5 pages

In this short note, we prove several new congruences for the overcubic partition triples function, using both elementary techniques and the theory of modular forms. These extend the recent list of such congruences given by Nayaka, Dharmendra, and Kumar (2024). We also generalize overcubic partition triples to overcubic partition $k$-tuples and prove a few arithmetic properties for these type of partitions., Comment: 12 pages, to appear in the Bulletin of the Australian Mathematical Society

Minimally invasive surgery (MIS) offers significant benefits such as reduced recovery time and minimised patient trauma, but poses challenges in visibility and access, making accurate 3D reconstruction a significant tool in surgical planning and navigation. This work introduces a robotic arm platform for efficient multi-view image acquisition and precise 3D reconstruction in MIS settings. We adapted a laparoscope to a robotic arm and captured ex-vivo images of several ovine organs across varying lighting conditions (operating room and laparoscopic) and trajectories (spherical and laparoscopic). We employed recently released learning-based feature matchers combined with COLMAP to produce our reconstructions. The reconstructions were evaluated against high-precision laser scans for quantitative evaluation. Our results show that whilst reconstructions suffer most under realistic MIS lighting and trajectory, many versions of our pipeline achieve close to sub-millimetre accuracy with an average of 1.05 mm Root Mean Squared Error and 0.82 mm Chamfer distance. Our best reconstruction results occur with operating room lighting and spherical trajectories. Our robotic platform provides a tool for controlled, repeatable multi-view data acquisition for 3D generation in MIS environments which we hope leads to new datasets for training learning-based models., Comment: 8 pages, 5 figures, 3 tables. This work has been submitted to the IEEE for possible publication

The extragalactic gamma-ray sky is dominated by relativistic jets aligned to the observer's line of sight, i.e., blazars. A few of their misaligned counterparts, e.g., radio galaxies, are also detected with the Fermi-Large Area Telescope (LAT) albeit in a small number ($\sim$50), indicating the crucial role played by the jet viewing angle in detecting gamma-ray emission from jets. These gamma-ray emitting misaligned active galactic nuclei (AGN) provide us with a unique opportunity to understand the high-energy emission production mechanisms from a different viewpoint than the more common blazars. With this goal in mind, we have systematically studied the radio morphology of gamma-ray emitting sources present in the fourth data release of the fourth catalog of Fermi-LAT detected gamma-ray sources to identify misaligned AGN. By utilizing the high-resolution and sensitive MHz and GHz frequency observations delivered by the Very Large Array Sky Survey, Low-Frequency Array Two-metre Sky Survey, Faint Images of the Radio Sky at Twenty-Centimeters, and Rapid ASKAP Continuum Survey, here we present a catalog of 149 gamma-ray detected misaligned AGN, thus $\sim$tripling the number of known objects of this class. Our sample includes a variety of radio morphologies, e.g., edge-darkened and edge-brightened, hybrids, wide-angle-tailed, bent jets, and giants. Since the gamma-ray emission is thought to be highly sensitive to the jet viewing angle, such an enlarged sample of gamma-ray detected misaligned radio sources will permit us to explore the origin of high-energy emission in relativistic jets and radio lobes and study AGN unification, in general., Comment: ApJ, in press

In this paper we study asymptotic moment of fourth power twisted Kloosterman sum. We write this moment as weighted sums of Hurwitz class numbers and to obtain the asymptotic moment formula we use the theory of harmonic Maass forms and Mock modular forms. As a result, we further obtain asymptotic averages of certain families of hypergeometric functions over large finite fields.

In this work we explore the applicability of unsupervised machine learning algorithms to the task of finding radio transients. Facilities such as the Square Kilometre Array (SKA) will provide huge volumes of data in which to detect rare transients; the challenge for astronomers is how to find them. We demonstrate the effectiveness of anomaly detection algorithms using 1.3 GHz light curves from the SKA precursor MeerKAT. We make use of three sets of descriptive parameters ('feature sets') as applied to two anomaly detection techniques in the Astronomaly package and analyse our performance by comparison with citizen science labels on the same dataset. By using transients found by volunteers as our ground truth, we demonstrate that anomaly detection techniques can recall over half of the radio transients in the 10 per cent of the data with the highest anomaly scores. We find that the choice of anomaly detection algorithm makes a minimal (sub-one per cent) level difference, but that feature set choice is crucial, especially when considering available resources for human inspection and/or follow-up. Active learning, where human labels are given for just 2 per cent of the data, improves recall by up to 10 percentage points, depending on the feature-model pair. The best performing feature-model pairs result in a factor of 5 times fewer sources requiring vetting by experts. This is the first effort to apply anomaly detection techniques to finding radio transients and shows great promise for application to other datasets, and as a real-time transient detection system for upcoming large surveys., Comment: Submitted to MNRAS, comments welcome! 17 pages, 9 Figures

In this paper, Chandrasekhar's deductive theory of turbulence is extended to the case of hydrodynamics and hydromagnetics, with higher order fluid moments. We include the contributions from correlation tensors at two different points of space and two different points in time to account for the energy transfer between Fourier modes with different $k$ values. We start with three governing equations using the first three moments of Vlasov equation, which gives us particle, momentum and energy conservation relations, respectively. We obtain the scalar representations of correlation tensors for hydrodynamics as well as hydromagnetics. Finally we pick an example from literature where the energy spectra alone was not capable of explaining the observations reported by the authors.

We investigate the impact of using multipoint p-T profiles of varying complexity on the retrieval of synthetically generated hot Jupiter transmission spectra modelled after state-of-the-art observations of the hot Jupiter WASP-39~b with JWST. We perform homogenised atmospheric retrievals with the TauREx retrieval framework on a sample of synthetically generated transmission spectra, accounting for varying cases of underlying p-T profiles, cloud-top pressures, and expected noise levels. These retrievals are performed using a fixed-pressure multipoint p-T prescription with increasing complexity, ranging from isothermal to an eleven-point profile. We evaluate the performance of the retrievals based on the Bayesian model evidence, and the accuracy of the retrievals compared to the known input parameters. We find that performing atmospheric retrievals using an isothermal prescription for the pressure-temperature profile consistently results in wrongly retrieved atmospheric parameters when compared to the known input parameters. For an underlying p-T profile with a fully positive lapse rate, we find that a two-point profile is sufficient to retrieve the known atmospheric parameters, while under the presence of an atmospheric temperature inversion, we find that a more complex profile is necessary. Our investigation shows that, for a data quality scenario mirroring state-of-the-art observations of a hot Jupiter with JWST, an isothermal p-T prescription is insufficient to correctly retrieve the known atmospheric parameters. We find a model complexity preference dependent on the underlying pressure-temperature structure, but argue that a p-T prescription on the complexity level of a four-point profile should be preferred. This represents the overlap between the lowest number of free parameters and highest model preference in the cases investigated in this work., Comment: 16 pages, 14 figures, accepted for publication in A&A

[Abridged] The relation between nuclear star clusters (NSCs) and the growth of the central SMBHs, as well as their connection to the properties of the host galaxies, is crucial for understanding the evolution of galaxies. Recent observations have revealed that about 10 per cent of nucleated galaxies host hybrid nuclei, consisting of both NSCs and accreting SMBHs that power active galactic nuclei (AGN). Motivated by the potential of the recently published multi-wavelength data sets from LeMMINGs survey, here we present the most thorough investigation to date of the incidence of hybrid nuclei in a large sample of 100 nearby nucleated galaxies (10 E, 25 S0, 63 S, and 2 Irr), covering a wide range in stellar mass ($M_{*,\rm gal} \sim 10^{8.7}-10^{12}~\rm M_{sun}$). We identify the nuclei and derive their properties by performing detailed 1D and 2D multi-component decompositions of the optical and near-infrared $HST$ stellar light distributions of the galaxies using S\'ersic and core-S\'ersic models. Our AGN diagnostics are based on homogeneously derived nuclear 1.5 GHz $e$-MERLIN radio, $Chandra$ X-ray (0.3--10 keV) and optical emission-line data. We determine the nucleation fraction ($f_{\rm nuc} $) as the relative incidence of nuclei across the LeMMINGs $HST$ sample and find $f_{\rm nuc} =~ $100/149 (= 67 $\pm$ 7 per cent), confirming previous work, with a peak value of 49/56~(= $88 \pm 13$ per cent) at bulge masses $M_{*,\rm bulge} \sim 10^{9.4}$- $10^{10.8}~\rm M_{sun}$. We identify 30 nucleated LeMMINGs galaxies that are optically active, radio-detected and X-ray luminous ($L_{X} > 10^{39}$ erg s$^{-1}$). This indicates that our nucleated sample has a lower limit $\sim$ 30 per cent occupancy of hybrid nuclei, which is a function of $M_{*,\rm bulge}$ and $M_{*,\rm gal}$. We find that hybrid nuclei have a number density of $(1.5 \pm 0.4) \times 10^{-5}$ Mpc$^{-3}$., Comment: Accepted for publication in MNRAS (21 pages, 10 figures, 9 tables)

To test the hypothesis that megaparsec-scale giant radio galaxies (GRGs) have multiple epochs of recurrent activity which lead to their giant sizes and to understand the nature of double-double radio galaxies (DDRGs), we have built the largest sample of giant DDRGs from the LOFAR Two Metre Sky Survey (LoTSS). The sample consists of 111 sources, of which 76 are newly identified. Their redshift and total projected size ranges are between 0.06 to 1.6 and 0.7 Mpc to 3.2 Mpc, respectively. We conducted a detailed analysis to characterise their properties, including arm-length ratios, flux density ratios of pairs of lobes, and misalignment angles. These measurements allow us to study the symmetry parameters, which are influenced by the immediate and large-scale environments of DDRGs. Our study conclusively shows that the cocoons in which the inner lobes of DDRGs grow are often contaminated with surrounding material from the external medium, leading to observed asymmetries in the inner lobes. Our analysis also reveals highly misaligned DDRGs, which could be due to environmental factors and/or changes in the supermassive black hole jet ejection axes. By studying the misalignment angles, we assess the stability of the jets in these systems in relation to their environment. Additionally, we have also characterised the large-scale environments of DDRGs, identifying them within dense galaxy clusters and studying how cluster weather significantly affects their morphologies. Interestingly, we have identified two gigahertz peaked-spectrum (GPS) candidates in the unresolved cores of the DDRGs, as well as one triple-double candidate, which, if confirmed, would be only the fifth known case. Additionally, we have discovered a DDRG in a distant galaxy cluster at $z\sim$\,1.4. Abridged., Comment: Submitted to A&A journal. 24 Pages. Comments are welcome

Recently, Drema and N. Saikia (2023) and M. P. Saikia, Sarma, and Sellers (2023) proved several congruences modulo powers of $2$ for overpartition triples with odd parts. In this paper, we study further divisibility properties of overpartition $k$-tuples with odd parts using elementary means as well as properties of modular forms. In particular, we prove several congruences modulo multiples of $3$, and an infinite family of congruences modulo powers of $3$; we also prove some cases of a conjecture of Saikia, Sarma, and Sellers., Comment: 21 pages

We build a new perspective to count perfect matchings of a given graph. This idea is motivated by a construction on the relative cohomology group of surfaces. As an application of our theory, we reprove the celebrated Aztec Diamond theorem, and show how alternating sign matrices naturally arises through this framework., Comment: 22 pages, 16 figures, comments are welcome

We present the first X-ray polarization measurements of GX 339-4. IXPE observed this source twice during its 2023-2024 outburst, once in the soft-intermediate state and again during a soft state. The observation taken during the intermediate state shows significant ($4\sigma$) polarization degree P = $1.3\% \pm 0.3\%$ and polarization angle $\theta$ = -74\degree $\pm$ 7\degree only in the 3 - 8 keV band. FORS2 at VLT observed the source simultaneously detecting optical polarization in the B, V, R, I bands (between $0.1%$ and $0.7\%$), all roughly aligned with the X-ray polarization. We also detect a discrete jet knot from radio observations taken later in time; this knot would have been ejected from the system around the same time as the hard-to-soft X-ray state transition and a bright radio flare occurred $\sim$3 months earlier. The proper motion of the jet knot provides a direct measurement of the jet orientation angle on the plane of the sky at the time of the ejection. We find that both the X-ray and optical polarization angles are aligned with the direction of the ballistic jet., Comment: Submitted to ApJ

In the past decade, it has been demonstrated that monolayers of metal dichalcogenides are well-suited for thermoelectric applications. ZrX2N4 (X = Si, Ge) is a reasonable choice for thermoelectric applications when considering a favorable value of the figure of merit in two-dimensional (2D) layered materials. In this study, we examined the thermoelectric characteristics of the two-dimensional monolayer of ZrX2N4 (where X can be either Si or Ge) using a combination of Density Functional Theory (DFT) and the Boltzmann Transport Equation (BTE). A thermoelectric figure of merit (ZT) of 0.90 was achieved at a temperature of 900 K for p-type ZrGe2N4, while a ZT of 0.83 was reported for n-type ZrGe2N4 at the same temperature. In addition, the ZrGe2N4 material exhibited a thermoelectric figure of merit (ZT) of around 0.7 at room temperature for the p-type. Conversely, the ZrSi2N4 exhibited a relatively lower thermoelectric figure of merit (ZT) at ambient temperature. At higher temperatures, the ZT value experiences a substantial increase, reaching 0.89 and 0.82 for p-type and n-type materials, respectively, at 900 K. Through our analysis of the electronic band structure, we have determined that ZrSi2N4 and ZrGe2N4 exhibit indirect bandgaps (BG) of 2.74 eV and 2.66 eV, respectively, as per the Heyd-Scuseria-Ernzerhof (HSE) approximation.

XTE J1701-462 is a neutron star low mass X-ray binary (NS LMXB) discovered in 2006 as the first system to demonstrate unambiguously that the `Atoll' and `Z' classes of accreting neutron stars are separated by accretion rate. Radio observations during the 2006/7 outburst provided evidence for the formation of a relativistic jet, as now expected for all accreting neutron star and black hole X-ray binaries at high accretion rates. The source entered a new outburst in 2022, and we report 29 observations made with the MeerKAT radio telescope. The first radio detection was on the 16th September 2022, we continued detecting the source until mid-December 2022. Thereafter, establishing radio upper limits till 25 March 2023. We present the radio analysis alongside analysis of contemporaneous X-ray observations from MAXI. The radio light curve shows evidence for at least three flare-like events over the first hundred days, the most luminous of which has an associated minimum energy of $1\times10^{38}$ erg. We provide a detailed comparison with the 2006/7 outburst, and demonstrate that we detected radio emission from the source for considerably longer in the more recent outburst, although this is probably a function of sampling. We further constrain the radio emission from the source to have a polarisation of less than 9% at the time of 2022 IXPE detection of X-ray polarisation. Finally, we place the source in the radio -- X-ray plane, demonstrating that when detected in radio it sits in a comparable region of parameter space to the other Z-sources., Comment: 8 pages, 4 figures, Accepted for publication in MNRAS

This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of 7.63 g-days is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and 1000 MeV/$c^2$, as well as upper limits on dark photon kinetic mixing and axion-like particle axioelectric coupling for masses between 1.2 and 23.3 eV/$c^2$. Compared to an earlier HVeV search, sensitivity was improved as a result of an increased overburden of 225 meters of water equivalent, an anticoincidence event selection, and better pile-up rejection. In the case of dark-matter-electron scattering via a heavy mediator, an improvement by up to a factor of 25 in cross-section sensitivity was achieved., Comment: 7 pages + title and references, 4 figures, and 1 table

Let $G=(V,E)$ be a finite connected simple graph with vertex set $V$ and edge set $E$. A signed Roman dominating function (SRDF) on a graph $G$ is a function $f: V \rightarrow \{-1, 1, 2\}$ that satisfies two conditions: (i) $\sum_{y\in N[x]} f(y)\geq1$ for each $x\in V$, where the set $N[x]$ is the closed neighborhood of $x$ consisting of $x$ and vertices of $V$ that are adjacent to $x$, and (ii) each vertex $x\in V$ where $f(x) = -1$ is adjacent to at least one vertex $y\in V$ where $f(y)=2$. The weight of a SRDF is the sum of its function values over all vertices. The signed Roman domination number of $G$, denoted by $\gamma_{SR}(G)$, is the minimum weight of a SRDF on $G$. In this paper, we investigate the signed Roman domination number of the Ladder graph $LG_n$, the circular Ladder graph $CL_n$ and their complements., Comment: 13 pages

Massive stars that travel at supersonic speeds can create bow shocks as their stellar winds interact with the surrounding interstellar medium. These bow shocks - prominent sites for mechanical feedback of individual massive stars - are predominantly observed in the infrared band. Confirmed high-energy emission from stellar bow shocks has remained elusive and confirmed radio counterparts, while rising in recent years, remain rare. Here, we present an in-depth multi-wavelength exploration of the bow shock driven by LS 2355, focusing on its non-thermal properties. Using the most-recent Fermi source catalogue, we rule out its previously-proposed association with an unidentified $\gamma$-ray source. Furthermore, we use deep ASKAP observations from the Rapid ASKAP Continuum Survey and the Evolutionary Map of the Universe survey to identify a non-thermal radio counterpart: the third spectrally confirmed non-thermal bow shock counterpart after BD +43$^{\rm o}$ 3654 and BD +60$^{\rm o}$ 2522. We finally use WISE IR data and Gaia to study the surrounding ISM and update the motion of LS 2355. Specifically, we derive a substantially reduced stellar velocity, $v_* = 7.0\pm2.5$ km/s, compared to previous estimates. The observed non-thermal properties of the bow shock can be explained by an interaction between the wind of LS 2355 and a dense HII region, at a magnetic field close to the maximum magnetic field strength allowed by the compressibility of the ISM. Similar to earlier works, we find that the thermal radio emission of the shocked ISM is likely to be substantially suppressed for it to be consistent with the observed radio spectrum., Comment: Accepted for publication in MNRAS

Neutral atomic hydrogen and molecular gas in the host galaxies of radio active galactic nuclei (AGN) can be traced using H I 21-cm and OH-1667 MHz absorption lines to understand the fueling and feedback processes. We present the results of an H I and OH absorption survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) towards 40 radio sources of low-intermediate radio luminosity ($\sim$10$^{23}$-10$^{26}$ W Hz$^{-1}$ at 1.4 GHz), red mid-infrared color (W2[4.6 $\mu$m]$-$W3[12 $\mu$m] $>$ 2.5 mag) and redshift up to 0.35. From 13 sources with good data at H I observing frequencies, we report the detection of H I absorption towards 8 sources, 5 of which are new detections including 4 in the redshift range 0.25 to 0.35. Our detection rates are consistent with our previous results with dependence on the star-formation history of the host galaxy reflected in the mid-infrared \textit{WISE} W2$-$W3 colors and the compactness of the radio source. We find no significant dependence of detection rates on radio luminosity or redshift. We also find that H I column densities are anti-correlated with the low-frequency spectral indices ($\alpha_{\rm 150 MHz}^{\rm 1.4 GHz}$, $S_{\nu}\propto \nu^{-\alpha}$). We do not have any detection from 23 sources with good data at OH observing frequencies. However, by stacking the spectra we estimate the 3$\sigma$ upper limit of OH column density to be 2.27$\times$10$^{14}$$T_{\rm ex}$/10 K $\times$1/$f_{\rm c}$ cm$^{-2}$. By stacking the OH spectra for 7 associated H I absorbers, we get a 3$\sigma$ upper limit of 3.47$\times$10$^{14}$ $T_{\rm ex}$/10 K $\times$1/$f_{\rm c}$ cm$^{-2}$ on OH column density and 1.78$\times$10$^{-7}$ on [OH]/[H I] ratio., Comment: 20 pages, 8 figures, accepted for publication in The Astrophysical Journal (ApJ)

Circumnuclear star formation (SF) is generally seen in galaxies hosting active galactic nuclei (AGN); however, the connection between the AGN activity and SF in them is less well understood. To explore this connection on scales of a few tens of parsec to a few tens of kiloparsec and larger, we carried out an investigation of SF in seven Seyfert type AGN and one LINER galaxy, using observations with the Ultra-Violet Imaging Telescope (UVIT) on board {\it AstroSat} in the near ultra-Violet (NUV; 2000-3000 \AA) and far ultra-Violet (FUV; 2000-3000 \AA) bands. A total of 1742 star-forming regions were identified, having size scales of 0.010 to 63.642 kpc$^2$. Considering all the galaxies, we found a positive correlation between their total surface density of SF ($\Sigma_{SFR}$) and extinction. For five galaxies, namely NGC 1365, NGC 4051, NGC 4321, NGC 5033 and NGC 6814, we found a gradual decrease of both extinction and $\Sigma_{SFR}$ from the centre to the outer regions. Four sources are found to lie in the main sequence (MS) of star-forming galaxies, and the other four are away from MS. We found the ratio of the star formation rate (SFR) in the nuclear region to the total SFR to be positively correlated with the Eddington ratio. This points to the influence of AGN on enhancing the SF characteristics of the hosts. However, the impact is dominant only in the central nuclear region with no significant effect on the larger scales probed in this work., Comment: Accepted for the publication of The Astrophysical Journal; Comments are welcome

PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO's target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile at the beginning of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases.

The accurate characterisation of the stellar magnetism of planetary host stars has been gaining momentum, especially in the context of transmission spectroscopy investigations of exoplanets. Indeed, the magnetic field regulates the amount of energetic radiation and stellar wind impinging on planets, as well as the presence of inhomogeneities on the stellar surface that hinder the precise extraction of the planetary atmospheric absorption signal. We initiated a spectropolarimetric campaign to unveil the magnetic field properties of known exoplanet hosting stars included in the current list of potential Ariel targets. In this work, we focus on HD 63433, a young solar-like star hosting two sub-Neptunes and an Earth-sized planet. These exoplanets orbit within 0.15 au from the host star and have likely experienced different atmospheric evolutionary paths. We analysed optical spectropolarimetric data collected with ESPaDOnS, HARPSpol, and Neo-Narval to compute the magnetic activity indices (log R'_HK , H$\alpha$, and Ca ii infrared triplet), measure the longitudinal magnetic field, and reconstruct the large-scale magnetic topology via Zeeman-Doppler imaging (ZDI). The magnetic field map was then employed to simulate the space environment in which the exoplanets orbit. The reconstructed stellar magnetic field has an average strength of 24 G and it features a complex topology with a dominant toroidal component, in agreement with other stars of a similar spectral type and age. Our simulations of the stellar environment locate 10% of the innermost planetary orbit inside the Alfv\'en surface and, thus, brief magnetic connections between the planet and the star can occur. The outer planets are outside the Alfv\'en surface and a bow shock between the stellar wind and the planetary magnetosphere could potentially form., Comment: 13 pages, 11 figures and 4 tables. Accepted in Astronomy and Astrophysics

We consider a special family of Gaussian hypergeometric functions whose entries are cubic and trivial characters over finite fields. The special values of these functions are known to give the Frobenius traces of families of Hessian elliptic curves. Using the theory of harmonic Maass forms and mock modular forms, we prove that the limiting distribution of these values is semi-circular (i.e. $SU(2)$), confirming the usual Sato-Tate distribution in this setting., Comment: Minor revisions addressing referee comments (e.g. correcting typos and adding references)

The newly emerged two-dimensional (2D) materials family of MSi2N4, where M is a transition metal atom (i.e., Mo, W, etc.), has the potential to be named after the conventional and very popular transition metal di-chalcogenides (TMDC), which got their reputation for having bandgap tunability and high mobility. The HfSi2N4 and HfGe2N4 2D materials are members of the MSi2N4 family and possess very good figure of merit (ZT) and have high mobility, proving their suitability for thermoelectric applications. The HfSi2N4 and HfGe2N4 showed considerable ZT of 0.90 and 0.89, respectively, for p-type and 0.83 and 0.79 for n-type, at 900 K along with high mobility according to the solutions obtained after solving the Boltzmann Transport Equation (BTE). The HfGe2N4 also showed a ZT of 0.84 at 600 K and 0.68 at 300 K, which is also excellent for low-temperature operation. The bandgaps (BG) obtained for HfSi2N4 and HfGe2N4 according to the Heyd-Scuseria-Ernzerhof (HSE) approximation were 2.89 eV and 2.75 eV. The first absorption peak showed in the blue region of the visible spectrum; from this, their usefulness in visible range photodetectors can also be inferred., Comment: 17 pages, 9 figures

We present an exact synthesis algorithm for qutrit unitaries in $\mathcal{U}_{3^n}(\mathbb{Z}[1/3,e^{2\pi i/3}])$ over the Clifford$+T$ gate set with at most one ancilla. This extends the already known result of qutrit metaplectic gates being a subset of Clifford$+T$ gate set with one ancilla. As an intermediary step, we construct an algorithm to convert 3-level unitaries into multiply-controlled gates, analogous to Gray codes converting 2-level unitaries into multiply-controlled gates. Finally, using catalytic embeddings, we present an algorithm to exactly synthesize unitaries $\mathcal{U}_{3^n}(\mathbb{Z}[1/3,e^{2\pi i/9}])$ over the Clifford$+T$ gate set with at most 2 ancillas. This, in particular, gives an exact synthesis algorithm of single-qutrit Clifford$+\mathcal{D}$ over the multi-qutrit Clifford$+T$ gate set with at most two ancillas., Comment: 16 pages, 4 figures

Exclusive diffractive processes, such as exclusive vector meson production, serve as excellent probes of hadron structure within the perturbative regime of quantum chromodynamics (QCD). The exclusive process involving light and heavy vector mesons, $e p \rightarrow e V(V=J/\Psi,\rho,\phi)$, has been investigated at the HERA accelerator facility. In this study, we focus on the theoretical prediction of exclusive $J/\Psi$ and $\rho^0$ vector meson production. Employing the color dipole description of deep inelastic scattering (DIS), we calculate both the differential cross-section and total cross-section of $J/\Psi$ and $\rho^0$ vector mesons, employing an analytical solution of the Balitsky-Kovchegov (BK) equation. Furthermore, we present the ratio of the longitudinal to the transverse cross-section for $J/\Psi$ and $\rho^0$ as a function of $Q^2$. Two well-known vector meson wave function models, Boosted Gaussian (BG) and Gaus-LC, have been integrated into our analysis, showing slight sensitivity to the chosen vector meson wave functions. Our theoretical predictions agree well with the available experimental data for vector meson production. The analytical solution of the BK equation proves reliable for the theoretical prediction of exclusive vector mesons within a specific range of $Q^2$., Comment: 22 pages, 8 captioned figures, new text added

The astrophysical $\gamma$-ray photons carry the signatures of the violent phenomena happening on various astronomical scales in our Universe. This includes supernova remnants, pulsars, and pulsar wind nebulae in the Galactic environment and extragalactic relativistic jets associated with active galactic nuclei (AGN). However, $\sim$30\% of the \gm-ray sources detected with the Fermi Large Area Telescope lack multiwavelength counterpart association, precluding us from characterizing their origin. Here we report, for the first time, the association of a collisional ring galaxy system in our Galactic neighborhood (distance $\sim$10 Mpc), formed as a consequence of a smaller `bullet' galaxy piercing through a larger galaxy, as the multi-frequency counterpart of an unassociated $\gamma$-ray source 4FGL~J1647.5$-$5724. The system, also known as "Kathryn's Wheel", contains two dwarf irregular galaxies and an edge-on, late-type, spiral galaxy surrounded by a ring of star-forming knots. We utilized observations taken from the Neil Gehrels Swift observatory, Rapid ASKAP Continuum Survey, SuperCOSMOS H$\alpha$ Survey, Dark Energy Survey, and Visible MultiObject Spectrograph at Very Large Telescope to ascertain the association with 4FGL~J1647.5$-$5724 and to explore the connection between the star-forming activities and the observed $\gamma$-ray emission. We found that star-formation alone cannot explain the observed $\gamma$-ray emission, and additional contribution likely from the pulsars/supernova remnants or buried AGN is required. We conclude that arcsecond/sub-arcsecond-scale observations of this extraordinary $\gamma$-ray emitting galaxy collision will be needed to resolve the environment and explore the origin of cosmic rays., Comment: ApJ Letters, in press

Stellar winds of cool main sequence stars are very difficult to constrain observationally. One way to measure stellar mass loss rates is to detect soft X-ray emission from stellar astrospheres produced by charge exchange between heavy ions of the stellar wind and cold neutrals of the interstellar medium (ISM) surrounding the stars. Here we report detections of charge-exchange induced X-ray emission from the extended astrospheres of three main sequence stars, 70 Ophiuchi, epsilon Eridani, and 61 Cygni based on analysis of observations by XMM-Newton. We estimate the corresponding mass loss rates to be 66.5 +- 11.1, 15.6 +- 4.4, and 9.6 +- 4.1 times the solar mass loss rate for 70 Ophiuchi, epsilon Eridani, and 61 Cygni, respectively, and compare our results to the hydrogen wall method. We also place upper limits on the mass loss rates of several other main sequence stars. This method has potential utility for determining the mass loss rates from X-ray observations showing spatial extension beyond a coronal point source., Comment: Published in Nature Astronomy on April 12th, 2024

We investigate theoretically magnetoentropic signatures of the crystal phase of magnetic skyrmions of various kinds, commonly appearing in two dimensions, \textit{viz.}, N\'eel, Bloch and anti skyrmions. Using Monte Carlo calculations based on spin Hamiltonians, we obtain magnetic entropy change $\Delta S_m$ in the presence of three different types of Dzyaloshinskii-Moriya interactions responsible for these skyrmions. The phase mapping of $\Delta S_m$ using skyrmion counting number $N_{sk}$ in temperature-magnetic field plane reveals fluctuation-dominated weak first-order transition in the precursor phase of the skyrmions, and a sign change in $\Delta S_m$ when the system enters into the skyrmion crystal phase -- in agreement with recent experimental findings. We also find that the fractional entropy change in going from a ferromagnetic phase to the skyrmion crystal phase is much larger compared to the conventional route of paramagnetic phase to ferromagnetic phase, used for the purpose of magnetic cooling. The magnetoentropic signatures of the different types of skyrmion crystals are found to be similar. Our results indicate that the skyrmion crystals exhibit enhanced cooling efficiency and have the potential to upgrade the existing magnetic cooling methods., Comment: 8 pages, 5 figures

We consider an infinite family of real quadratic fields $k$ where the discriminant has three distinct odd prime factors, and the prime 2 splits. We show that the unramified Iwasawa module $X(k_{\infty})$ associated with the $\mathbb{Z}_2$-extension of $k$ has a bounded quotient. Thus, we also verify Greenberg's conjecture on the vanishing of Iwasawa invariants for such fields and obtain a finer structure for $X(k_{\infty})$.

We associate quantum states with subsets of a product of two compact connected K\"ahler manifolds $M_1$ and $M_2$. To associate the quantum state with the subset, we use the map that restricts holomorphic sections of the quantum line bundle over the product of the two K\"ahler manifolds to the subset. We present a description of the kernel of this restriction map when the subset is a finite union of products. This in turn shows that the quantum states associated with the finite union of products are separable. Finally, for every pure state and certain mixed state, we construct subsets of $M_1\times M_2$ such that the states associated with these subsets are the original states, to begin with.

Undetected infectious populations have played a major role in the COVID-19 outbreak across the globe and estimation of this undetected class is a major concern in understanding the actual size of the COVID-19 infections. Due to the asymptomatic nature of some infections, many cases have gone undetected. Also, despite carrying COVID-19 symptoms, most of the infected population kept the infections hidden and stayed unreported, especially in a country like India. Based on these factors, we have added an undetected compartment to the already developed SEIR model [48] to estimate these uncounted infections. In this article, we have applied Physics Informed Neural Network (PINN) to estimate the undetected infectious populations in the 20 worst-affected Indian states as well as India as a whole. The analysis has been carried out for the first as well as second surge of COVID-19 infections in India. A ratio of the active undetected infectious to the active detected infectious population is calculated through the PINN analysis which gives a picture of the real size of the pandemic in India. The rate at which symptomatic infectious population goes undetected and are never reported is also estimated using the PINN method. Toward the end, an artificial neural network (ANN) based forecasting scenario of the pandemic in India is presented. The prediction is found to be reliable as the training of the neural network has been carried out using the unique features, obtained from the state-wide analysis of the newly proposed model as well as from the PINN analysis., Comment: 16 pages, 6 figures, 4 tables