Papers for Monday, Aug 21 2023

We infer the dynamical masses of stars across the Hertzsprung-Russell (H-R) diagram using wide binaries from the Gaia survey. Gaia's high-precision astrometry measures the wide binaries' orbital motion, which contains the mass information. Using wide binaries as the training sample, we measure the mass of stars across the two-dimensional H-R diagram using the combination of statistical inference and neural networks. Our results provide the dynamical mass measurements for main-sequence stars from 0.1 to 2 M$_\odot$, unresolved binaries and unresolved triples on the main sequence, and the mean masses of giants and white dwarfs. Two regions in the H-R diagram show interesting behaviors in mass, where one of them is pre-main-sequence stars, and the other one may be related to close compact object companions like M dwarf-white dwarf binaries. These mass measurements depend solely on Newtonian dynamics, providing independent constraints on stellar evolutionary models and the occurrence rate of compact objects.

Magnetars are highly magnetized neutron stars; their formation mechanism is unknown. Hot helium-rich stars with spectra dominated by emission lines are known as Wolf-Rayet stars. We observe the binary system HD 45166 using spectropolarimetry, finding that it contains a Wolf-Rayet star with a mass of 2 solar masses and a magnetic field of 43 kilogauss. Stellar evolution calculations indicate that this component will explode as a type Ib or IIb supernova, and the strong magnetic field favors a magnetar remnant. We propose that the magnatized Wolf-Rayet star formed by the merger of two lower mass helium stars.

The non-Gaussian part of the covariance matrix of the galaxy power spectrum involves the connected four-point correlation in Fourier space, i.e. trispectrum. This paper introduces a fast method to compute the non-Gaussian part of the covariance matrix of the galaxy power spectrum multipoles in redshift space at tree-level standard perturbation theory. For the tree-level galaxy trispectrum, the angular integral between two wavevectors can be evaluated analytically by employing an FFTLog. The new implementation computes the non-Gaussian covariance of the power spectrum monopole, quadrupole, hexadecapole and their cross-covariance in O(10) seconds, for an effectively arbitrary number of instances of cosmological and galaxy bias parameters and redshift, without any parallelization or acceleration. It is a large advantage over conventional numerical integration. We demonstrate that the computation of the covariance at k = 0.005 - 0.4 h/Mpc gives results with 0.1 - 1% accuracy. The efficient computation of the analytic covariance can be useful for future galaxy surveys, especially utilizing multi-tracer analysis.

In recent years, there has been a remarkable development of simulation-based inference (SBI) algorithms, and they have now been applied across a wide range of astrophysical and cosmological analyses. There are a number of key advantages to these methods, centred around the ability to perform scalable statistical inference without an explicit likelihood. In this work, we propose two technical building blocks to a specific sequential SBI algorithm, truncated marginal neural ratio estimation (TMNRE). In particular, first we develop autoregressive ratio estimation with the aim to robustly estimate correlated high-dimensional posteriors. Secondly, we propose a slice-based nested sampling algorithm to efficiently draw both posterior samples and constrained prior samples from ratio estimators, the latter being instrumental for sequential inference. To validate our implementation, we carry out inference tasks on three concrete examples: a toy model of a multi-dimensional Gaussian, the analysis of a stellar stream mock observation, and finally, a proof-of-concept application to substructure searches in strong gravitational lensing. In addition, we publicly release the code for both the autoregressive ratio estimator and the slice sampler.

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 85.69 and 99.02 GHz continuum emission and H42$\alpha$ and H40$\alpha$ lines emission from the central 1~kpc of NGC 1808. These forms of emission are tracers of photoionizing stars but unaffected by dust obscuration that we use to test the applicability of other commonly star formation metrics. An analysis of the spectral energy distributions shows that free-free emission contributes about 60 to 90 per cent of the continuum emission in the 85-100 GHz frequency range, dependent on the region. The star formation rate (SFR) derived from the ALMA free-free emission is $3.1\pm0.3$~M$_\odot$~yr$^{-1}$. This is comparable to the SFRs measured from the infrared emission, mainly because most of the bolometric energy from the heavily obscured region is emitted as infrared emission. The radio 1.5~GHz emission yields a SFR 25 per cent lower than the ALMA value, probably because of the diffusion of the electrons producing the synchrotron emission beyond the star-forming regions. The SFRs measured from the extinction-corrected H$\alpha$ line emission are about 40 to 65 per cent of the SFR derived from the ALMA data, likely because this metric was not calibrated for high extinction regions. Some SFRs based on extinction-corrected ultraviolet emission are similar to those from ALMA and infrared data, but given that the ultraviolet terms in the extinction correction equations are very small, these metrics seem inappropriate to apply to this dusty starburst.

We present deep Hubble Space Telescope imaging of the nearby Type Ia supernova (SN Ia) 2011fe obtained 11.5yr after explosion. No emission is detected at the SN location to a $1\sigma$ ($3\sigma$) limit of ${F555W > 30.2 \;(29.0)}~$mag, or equivalently $M_V > 1.2 \;(-0.1)~$mag, neglecting the distance uncertainty to M101. We constrain the presence of donor stars impacted by the SN ejecta with the strictest limits thus far on compact (i.e., $\log \,g \gtrsim 4$) companions. H-rich zero-age main-sequence companions with masses $\geq 2~\rm M_\odot$ are excluded, a significant improvement upon the pre-explosion imaging limit of $\approx 5~\rm M_\odot$. Main-sequence He stars with masses $\geq 0.5~\rm M_\odot$ and subgiant He stars with masses $\lesssim 1~\rm M_\odot$ are also disfavored by our late-time imaging. Synthesizing our limits on post-impact donors with previous constraints from pre-explosion imaging, early-time radio and X-ray observations, and nebular-phase spectroscopy, essentially all formation channels for SN2011fe invoking a non-degenerate donor star at the time of explosion are unlikely.

We present a spectroscopic analysis of Eridanus IV (Eri IV) and Centaurus I (Cen I), two ultra-faint dwarf galaxies of the Milky Way. Using IMACS/Magellan spectroscopy, we identify 28 member stars of Eri IV and 34 member stars of Cen I. For Eri IV, we measure a systemic velocity of $v_{sys} = -31.5^{+1.3}_{-1.2}\:\mathrm{km\:s^{-1}}$ and velocity dispersion $\sigma_{v}= 6.1^{+1.2}_{-0.9}\:\mathrm{km\:s^{-1}}$. Additionally, we measure the metallicities of 16 member stars of Eri IV. We find a metallicity of $\mathrm{[Fe/H]}=-2.87^{+0.08}_{-0.07}$ and resolve a dispersion of $\sigma_{\mathrm{[Fe/H]}} = 0.20\pm0.09$. The mean metallicity is marginally lower than all other known ultra-faint dwarf galaxies, making it one of the most metal-poor galaxies discovered thus far. Eri IV also has a somewhat unusual right-skewed metallicity distribution. For Cen I, we find a velocity $v_{sys} = 44.9\pm0.8\:\mathrm{km\:s^{-1}}$ and velocity dispersion $\sigma_{v} = 4.2^{+0.6}_{-0.5} \:\mathrm{km\:s^{-1}}$. We measure the metallicities of 27 member stars of Cen I, and find a mean metallicity $\mathrm{[Fe/H]} = -2.57\pm0.08$ and metallicity dispersion $\sigma_{\mathrm{[Fe/H]}} = 0.38^{+0.07}_{-0.05}$. We calculate the systemic proper motion, orbit, and the astrophysical J-factor for each system, the latter of which indicates that Eri IV is a good target for indirect dark matter detection. We also find no strong evidence for tidal stripping of Cen I or Eri IV. Overall, our measurements confirm that Eri IV and Cen I are dark matter-dominated galaxies with properties largely consistent with other known ultra-faint dwarf galaxies. The low metallicity, right-skewed metallicity distribution, and high J-factor make Eri IV an especially interesting candidate for further followup.

The tight correlations between the masses of supermassive black holes (BHs) and the properties of their host galaxies suggest that BHs coevolve with galaxies. However, what is the link between BH mass ($M_{\rm BH}$) and the properties of the host galaxies of active galactic nuclei (AGNs) in the nearby Universe? We measure stellar masses ($M_*$), colors, and structural properties for $\sim11,500$ $z\leq0.35$ broad-line AGNs, nearly 40 times larger than that in any previous work. We find that early-type and late-type AGNs follow a similar $M_{\rm BH}-M_*$ relation. The position of AGNs on the $M_{\rm BH}-M_*$ plane is connected with the properties of star formation and BH accretion. Our results unveil the evolutionary paths of galaxies on the $M_{\rm BH}-M_*$ plane: objects above the relation tend to evolve more horizontally with substantial $M_*$ growth; objects on the relation move along the local relation; and objects below the relation migrate more vertically with substantial $M_{\rm BH}$ growth. These trajectories suggest that radiative-mode feedback cannot quench the growth of BHs and their host galaxies for AGNs that lie below the relation, while kinetic-mode feedback hardly suppress long-term star formation for AGNs situated above the relation. This work provides important constraints for numerical simulations and offers a framework for studying the cosmic coevolution of supermassive BHs and their host galaxies.

Using a sample of $>200$ clusters, each with typically $100-200$ spectroscopically confirmed cluster members, we search for a signal of alignment between the Position Angle (PA) of the Brightest Cluster Galaxy (BCG) and the distribution of cluster members on the sky about the cluster centre out to projected distances of 3~R$_{200}$. The deep spectroscopy, combined with corrections for spectroscopic incompleteness, makes our sample ideal to determine alignment signal strengths. We also use an SDSS based skeleton of the filamentary Large Scale Structure (LSS), and measure BCG alignment with the location of the LSS skeleton segments on the sky out to projected distances of 10~R$_{200}$. The alignment signal is measured using three separate statistical measures; Rao's spacing test (U), Kuiper's V parameter (V), and the Binomial probability test (P). The significance of the BCG alignment signal with both cluster members and LSS segments is extremely high (1 in a million chance or less to be drawn randomly from a uniform distribution). We investigate a wide set of parameters that may influence the strength of the alignment signal. Clusters with more elliptical-shaped BCGs show stronger alignment with both their cluster members and LSS segments. Also, selecting clusters with closely connected filaments, or using a luminosity-weighted LSS skeleton, increases the alignment signal significantly. Alignment strength decreases with increasing projected distance. Combined, these results provide strong evidence for the growth of clusters and their BCGs by preferential feeding along the direction of the filaments in which they are embedded.

We suggest that "$G$ objects" recently discovered in the Galactic Center may be clouds of gas bound by the gravitational field of stellar-mass black holes produced in the interactions of sublunar primordial black holes with neutron stars. If dark matter is composed of primordial black holes with masses $(10^{-16} - 10^{-10}) M_\odot$, these black holes can be captured by neutron stars in the Galactic Center, where the dark matter density is high. After the capture, the neutron star is consumed by the black hole, resulting in a population of $(1-2) M_\odot $ black holes. These stellar-mass black holes, accompanied by gaseous atmospheres, can account for the observed properties of the $G$ objects, including their resilience to tidal disruption by the supermassive black hole in the Galactic Center while also producing emission consistent with inferred luminosities.

Context. Globular clusters carry information about the formation histories and gravitational fields of their host galaxies. B\'ilek et al. (2019, BSR19 hereafter) reported that the radial profiles of volume number density of GCs in GC systems (GCS) follow broken power laws, while the breaks occur approximately at the $a_0$ radii. These are the radii at which the gravitational fields of the galaxies equal the galactic acceleration scale $a_0 = 1.2 \times 10^{-10}$ms$^{-2}$ known from the radial acceleration relation or the MOND theory of modified dynamics. Aims. Our main goals here are to explore whether the results of BSR19 hold true for galaxies of a wider mass range and for the red and blue GCs sub-populations. Methods. We exploited catalogs of photometric GC candidates in the Fornax galaxy cluster based on ground and space observations and a new catalog of spectroscopic GCs of NGC 1399, the central galaxy of the cluster. For every galaxy, we obtained the parameters of the broken power law density by fitting the on-sky distribution of the GC candidates, while allowing for a constant density of contaminants. The logarithmic stellar masses of our galaxy sample span 8.0-11.4 $M_\odot$. Results. All investigated GCSs with a sufficient number of members show broken power-law density profiles. This holds true for the total GC population and the blue and red subpopulations. The inner and outer slopes and the break radii agree well for the different GC populations. The break radii agree with the $a_0$ radii typically within a factor of two for all GC color subpopulations. The outer slopes correlate better with the $a_0$ radii than with the galactic stellar masses. The break radii of NGC 1399 vary in azimuth, such that they are greater toward and against the neighboring galaxy NGC 1404.

Context. MWC 656 was reported as the first known Be star with a black-hole (BH) companion in a 60 d period. The mass of the proposed BH companion is estimated to be between 4 - 7 MSun. This estimate is based on radial velocity (RV) measurements derived from the Fe ii 4583 emission line of the Be star disc and from the He ii 4686 emission line, assumed to be formed in a disc around the putative BH. Aims. Using new high-resolution spectroscopic data, we investigate whether MWC 656 truly contains a BH. Methods. We used the cross-correlation method to calculate the RVs of both the Be star and the He ii 4686 emission line and we derive a new orbital solution. We also performed disentangling to look for the spectral signature of a companion. Results. We derive an orbital period of 59.028 +- 0.011 d and a mass ratio q = M_Heii/M_Be = 0.12 +- 0.03, much lower than the previously reported q = 0.41 +- 0.07. Adopting a mass of the Be star of M_Be = 7.8 +- 2.0MSun, the companion has a mass of 0.94 +- 0.34MSun. For the upper limit of M_Be = 16MSun and q = 0.15, the companion has a mass 2.4MSun. Performing disentangling on mock spectra shows that the spectral signature of a non-degenerate stellar companion with such a low mass cannot be retrieved using our data. Conclusions. Our measurements do not support the presence of a BH companion in MWC 656. The derived upper limit on the mass of the companion rather indicates that it is a neutron star, a white dwarf, or a hot helium star. Far-UV data will help to reject or confirm a hot helium-star companion.

Comet 107P/Wilson-Harrington, cross-listed as asteroid 4015, is one of the original transition objects whose properties do not neatly fit into a cometary or asteroidal origin. Discovered in a period of apparently gas-dominated activity in 1949, it was subsequently lost and recovered as the inactive asteroid 1979 VA. We obtained new and re-analyzed archival observations of the object, compared to meteorites, and conducted new orbital integrations in order to understand the nature of this object and to understand where it falls on the asteroid-comet continuum. Wilson-Harrington's reflectance spectrum is approximately neutral from visible to near-infrared wavelengths, but has a reflectance maximum near 0.8-0.9 microns. The object's spectrum is well matched by laboratory spectra of carbonaceous chondrite meteorites like the CM Murchison or the CI Ivuna. The object's phase curve is compatible with either an asteroidal or cometary origin, and its recent orbital history has no periods with high enough temperatures to have altered its surface. While it is possible that some unknown process has acted to change the surface from an originally cometary one, we instead prefer a fundamentally asteroidal origin for Wilson-Harrington which can explain its surface and orbital properties. However, this would require a way to maintain significant (hyper-)volatile supplies on the near-Earth objects beyond what is currently expected. Wilson-Harrington's similar meteorite affinity and possible orbital link to sample return targets (162173) Ryugu and (101955) Bennu suggest that the returned samples from the Hayabusa-2 and OSIRIS-REx missions might hold the key to understanding this object.

We present observations of population anti-inversion in the $3_1 - 4_0\ A^+$ transition of CH$_3$OH (methanol) at 107.013831 GHz toward the Galactic Center cloud G0.253+0.016 ("The Brick"). Anti-inversion of molecular level populations can result in absorption lines against the cosmic microwave background (CMB) in a phenomenon known as a "dasar." We model the physical conditions under which the 107 GHz methanol transition dases and determine that dasing occurs at densities below $10^6$ cm$^{-3}$ and column densities between $10^{13}$ and $10^{16}$ cm$^{-2}$. We also find that for this transition, dasing does not strongly depend on the gas kinetic temperature. We evaluate the potential of this tool for future deep galaxy surveys. We note that other works have already reported absorption in this transition (e.g., in NGC 253), but we provide the first definitive evidence that it is absorption against the CMB rather than against undetected continuum sources.

We present a study of the galaxy Lyman-alpha luminosity function (LF) using a sample of 17 lensing clusters observed by the MUSE/VLT. Magnification from strong gravitational lensing by clusters of galaxies and MUSE apabilities allow us to blindly detect LAEs without any photometric pre-selection, reaching the faint luminosity regime. 600 lensed LAEs were selected behind these clusters in the redshift range 2.9<$z$< 6.7, covering four orders of magnitude in magnification-corrected Lyman-alpha luminosity (39.0<log$L$< 43.0). The method used in this work ($V_{\text{max}}$) follows the recipes originally developed by arXiv:1905.13696(N) (DLV19) with some improvements to better account for the effects of lensing when computing the effective volume. The total co-moving volume at 2.9<$z$<6.7 is $\sim$50 $10^{3}Mpc^{3}$. Our LF points in the bright end (log L)>42 are consistent with those obtained from blank field observations. In the faint luminosity regime, the density of sources is well described by a steep slope, $\alpha\sim-2$ for the global redshift range. Up to log(L)$\sim$41, the steepening of the faint end slope with redshift, suggested by the earlier work of DLV19 is observed, but the uncertainties remain large. A significant flattening is observed towards the faintest end, for the highest redshift bins (log$L$<41). Using face values, the steep slope at the faint-end causes the SFRD to dramatically increase with redshift, implying that LAEs could play a major role in the process of cosmic reionization. The flattening observed towards the faint end for the highest redshift bins still needs further investigation. This turnover is similar to the one observed for the UV LF at $z\geq6$ in lensing clusters, with the same conclusions regarding the reliability of current results (e.g.arXiv:1803.09747(N); arXiv:2205.11526(N)).

Ultra-short period planets (USPs) are a unique class of super-Earths with an orbital period of less than a day and hence subject to intense radiation from their host star. While most of them are consistent with bare rocks, some show evidence of a heavyweight envelope, which could be a water layer or a secondary metal-rich atmosphere sustained by an outgassing surface. Much remains to be learned about the nature of USPs. The prime goal of the present work is to study the bulk planetary properties and atmosphere of TOI-561b, through the study of its transits and occultations. We obtained ultra-precise transit photometry of TOI-561b with CHEOPS and performed a joint analysis of this data with four TESS sectors. Our analysis of TOI-561b transit photometry put strong constraints on its properties, especially on its radius, Rp=1.42 +/- 0.02 R_Earth (at ~2% error). The internal structure modelling of the planet shows that the observations are consistent with negligible H/He atmosphere, however requiring other lighter materials, in addition to pure iron core and silicate mantle to explain the observed density. We find that this can be explained by the inclusion of a water layer in our model. We searched for variability in the measured Rp/R* over time to trace changes in the structure of the planetary envelope but none found within the data precision. In addition to the transit event, we tentatively detect occultation signal in the TESS data with an eclipse depth of ~27 +/- 11 ppm. Using the models of outgassed atmospheres from the literature we find that the thermal emission from the planet can mostly explain the observation. Based on this, we predict that NIR/MIR observations with JWST should be able to detect silicate species in the atmosphere of the planet. This could also reveal important clues about the planetary interior and help disentangle planet formation and evolution models.

We present the serendipitous detection of a new Galactic Supernova Remnant (SNR), G288.8-6.3 using data from the Australian Square Kilometre Array Pathfinder (ASKAP)-Evolutionary Map of the Universe (EMU) survey. Using multi-frequency analysis, we confirm this object as an evolved Galactic SNR at high Galactic latitude with low radio surface brightness and typical SNR spectral index of $\alpha = -0.41\pm0.12$. To determine the magnetic field strength in SNR G288.8-6.3, we present the first derivation of the equipartition formulae for SNRs with spectral indices $\alpha>-0.5$. The angular size is $1.\!^\circ 8\times 1.\!^\circ 6$ $(107.\!^\prime 6 \times 98.\!^\prime 4)$ and we estimate that its intrinsic size is $\sim40$pc which implies a distance of $\sim1.3$kpc and a position of $\sim140$pc above the Galactic plane. This is one of the largest angular size and closest Galactic SNRs. Given its low radio surface brightness, we suggest that it is about 13000 years old.

The release of Gaia catalog is revolutionary to the astronomy of solar system objects. After some effects such as atmospheric refraction and CCD geometric distortion have been taken into account, the astrometric precision for ground-based telescopes can reach the level of tens of milli-arcseconds. If an object approaches a reference star in a small relative angular distance (less than 100 arcseconds), which is called close approach event in this work, the relative positional precision between the object and reference star will be further improved since the systematic effects of atmospheric turbulence and local telescope optics can be reduced. To obtain the precise position of a main-belt asteroid in an close approach event, a second-order angular velocity model with time is supposed in the sky plane. By fitting the relationship between the relative angular distance and observed time, we can derive the time of maximum approximation and calculate the corresponding position of the asteroid. In practice, 5 nights' CCD observations including 15 close approach events of main-belt asteroid (702) Alauda are taken for testing by the 1m telescope at Yunnan Observatory, China. Compared with conventional solutions, our results show that the positional precision significantly improves, which reaches better than 4 milli-arcseconds, and 1 milli-arcsecond in the best case when referenced for JPL ephemeris in both right ascension and declination.

We introduce a framework to measure the asphericity of Sun-like stars using $a_1$, $a_2$ and $a_4$ coefficients, and constrain their latitudes of magnetic activity. Systematic errors on the inferred coefficients are evaluated in function of key physical and seismic parameters (inclination of rotation axis, average rotation, height-to-noise ratio of peaks in power spectrum). The measured a-coefficients account for rotational oblateness and the effect of surface magnetic activity. We use a simple model that assumes a single latitudinal band of activity. Using solar SOHO/VIRGO/SPM data, we demonstrate the capability of the method to detect the mean active latitude and its intensity changes between 1999-2002 (maximum of activity) and 2006-2009 (minimum of activity). We further apply the method to study the solar-analogue stars 16 Cyg A and B using Kepler observations. An equatorial band of activity, exhibiting intensity that could be comparable to that of the Sun, is detected in 16 Cyg A. However, 16 Cyg B exhibits a bi-modality in $a_4$ that is challenging to explain. We suggest that this could be a manifestation of the transition between a quiet and an active phase of activity. Validating or invalidating this hypothesis may require new observations.

We present observations of the vdB 130 cluster vicinity in a narrow-band filter centered at a $2.12\,\mu$m molecular hydrogen line performed at the Caucasus Mountain Observatory of the Lomonosov Moscow State University. The observations reveal an H$_2$ emission shell around vdB 130, coincident with a bright infrared shell, visible in all \textit{Spitzer} bands. Also, numerous H$_{2}$ emission features are detected around infrared Blobs E and W and in the vicinity of a protocluster located to the east of the shell, in a tail of a cometary molecular cloud. H$_2$ emission in the vicinity of the vdB~130 cluster is mostly generated in well-developed \HII\ regions and is of fluorescent nature. In the protocluster area, isolated spots are observed, where H$_2$ emission is collisionally excited and is probably related to shocks in protostellar outflows. Obtained results are discussed in the context of possible sequential star formation in the vicinity of the vdB 130 cluster, triggered by the interaction of the expanding supershell surrounding the Cyg OB1 association with the molecular cloud and an associated molecular filament.

Over three thousand pulsars have been discovered, but none have been confirmed to be younger than a few hundred years. Observing a pulsar after a supernova explosion will help us understand the properties of newborn ones, including their capability to produce gamma-ray bursts and fast radio bursts. Here, the possible youngest pulsar wind nebula (PWN) at the center of the SN 1986J remnant is studied. We demonstrate that the 5 GHz flux of 'PWN 1986J', increasing with time, is consistent with a stochastic acceleration model of PWNe developed to explain the flat radio spectrum of the Crab Nebula. We obtain an acceleration time-scale of electrons/positrons and a decay time-scale of the turbulence responsible for the stochastic acceleration as about 10 and 70 years, respectively. Our findings suggest that efficient stochastic acceleration and rising radio/submm light curves are characteristic signatures of the youngest PWNe. Follow-up ${\it ALMA}$ observations of decades-old supernovae within a few tens of Mpc, including SN 1986J, are encouraged to reveal the origin of the flat radio spectrum of PWNe.

Solar filaments often exhibit rotation and deflection during eruptions, which would significantly affect the geoeffectiveness of the corresponding coronal mass ejections (CMEs). Therefore, understanding the mechanisms that lead to such rotation and lateral displacement of filaments is a great concern to space weather forecasting. In this paper, we examine an intriguing filament eruption event observed by the Chinese H{\alpha} Solar Explorer (CHASE) and the Solar Dynamics Observatory (SDO). The filament, which eventually evolves into a CME, exhibits significant lateral drifting during its rising. Moreover, the orientation of the CME flux rope axis deviates from that of the pre-eruptive filament observed in the source region. To investigate the physical processes behind these observations, we perform a data-constrained magnetohydrodynamic (MHD) simulation. Many prominent observational features in the eruption are reproduced by our numerical model, including the morphology of the eruptive filament, eruption path, and flare ribbons. The simulation results reveal that the magnetic reconnection between the flux-rope leg and neighboring low-lying sheared arcades may be the primary mechanism responsible for the lateral drifting of the filament material. Such a reconnection geometry leads to flux-rope footpoint migration and a reconfiguration of its morphology. As a consequence, the filament material hosted in the flux rope drifts laterally, and the CME flux rope deviates from the pre-eruptive filament. This finding underscores the importance of external magnetic reconnection in influencing the orientation of a flux rope axis during eruption.

In this work, we report the first result from the investgation of Neutral atomic hydrogen(HI) 21cm absorption line in spectrum of PKS1413+135 as a associated type at redshift $z\approx 0.24670041$ observed by FAST using the observing time of 10 minutes for the absorber and the spectral resolution of the raw data was setted to 10 Hz. The full spectral profile is analysed by fitting the absorption line with single Gaussian function as the resolution of 10kHz in 2MHz bandwidth, eventually intending to illustrate the latest cosmic acceleration by the direct measurement of time evolution of the redshift of HI 21cm absorption line with Hubble flow toward a same background Quasar in the time interval of more than a decade or many years as a detectable signal that produced by the accelerated expansion of the Universe in the era of FAST at low redshift space,namely redshift drift $\dot{z}$ or SL effect. The obtained HI gas column density $\rm N_{HI} \approx 2.2867\times 10^{22}/cm^2$ of this DLA system, much equivalent to the originally observed value $\rm N_{HI} \approx 1.3\times 10^{19}\times(T_s/f)/cm^2$ within the uncertainties of the spin temperature of a spiral host galaxy, and the signal to noise ratio SNR highly reaching 57.4357 for the resolution of 10kHz evidently validates the opportunities of the HI 21cm absorption lines of DLA systems to enforce the awareness of the physical motivation of dark energy by the probe of $\rm\dot{z}$ with the enhancement of accuracy in the level of $\sim 10^{-10}$ per decade.

Spectral and photometric variability of the Classical T Tauri stars RY Tau and SU Aur from 2013 to 2022 is analyzed. We find that in SU Aur the H-alpha line's flux at radial velocity RV = -50 +- 7 km/s varies with a period P = 255 +- 5 days. A similar effect previously discovered in RY Tau is confirmed with these new data: P = 21.6 days at RV = -95 +- 5 km/s. In both stars, the radial velocity of these variations, the period, and the mass of the star turn out to be related by Kepler's law, suggesting structural features on the disc plane orbiting at radii of 0.2 AU in RY Tau and 0.9 AU in SU Aur, respectively. Both stars have a large inclination of the accretion disc to the line of sight - so that the line of sight passes through the region of the disc wind. We propose there is an azimuthal asymmetry in the disc wind, presumably in the form of 'density streams', caused by substructures of the accretion disc surface. These streams cannot dissipate until they go beyond the Alfven surface in the disc's magnetic field. These findings open up the possibility to learn about the structure of the inner accretion disc of CTTS on scales less than 1 AU and to reveal the orbital distances related to the planet's formation.

This study presented a new analysis for the TESS-observed W Ursae Majoris (W UMa) binary star YY Coronea Borealis (YY CrB). The light curve was analyzed by the PHysics Of Eclipsing BinariEs (PHOEBE) Python version together with the Markov chain Monte Carlo (MCMC) method. The light curve solutions required a hot spot and l3. New eclipse times from the TESS observations were extracted, and the O-C curve of primary and secondary minima showed an anti-correlated manner. In order to study the O-C curve of minima, minima times between 1991 and 2023 were collected. This investigation reported a new linear ephemeris and by fitting a quadratic function to the O-C curve of minima, calculated the orbital period rate of \mathop P\limits^.\approx 5.786*{10^{-8}} day/year. Assuming mass conservation, a mass exchange rate of \mathop{{M_2}}\limits^.=2.472*{10^{-8}} calculated from the more massive component to the less massive one. Then, by using the light travel time function, the possible third body was determined in the binary and derived the mass of the third body as 0.498M_Sun with a period of \simeq 7351.018 days. The O-C curve analysis and the quantity of mass indicate that the presence of a third body is unlikely. This binary is expected to evolve into a broken-contact phase and is a good case to support the thermal relaxation oscillation model.

Interactions between global coronal waves (CWs) and coronal holes (CHs) reveal many interesting features of reflected waves and coronal hole boundaries (CHB) but have fairly been studied so far. Magnetohydrodynamic (MHD) simulations can help us to better understand what is happening during these interaction events, and therefore, to achieve a broader understanding of the parameters involved. In this study, we perform for the first time 2D MHD simulations of a CW-CH interaction including a realistic initial wave density profile that consists of an enhanced as well as a depleted wave part. We vary several initial parameters, such as the initial density amplitudes of the incoming wave, the CH density, and the CHB width, which are all based on actual measurements. We analyse the effects of different incident angles on the interaction features and we use the corresponding time-distance plots to detect specific features of the incoming and the reflected wave. We found that a particular combination of a small CH density, a realistic initial density profile and a sufficiently small incident angle leads to remarkable interaction features, such as a large density amplitude of the reflected wave with respect to the incoming one. The parameter studies in this paper provide a tool to compare time-distance plots based on observational measurements to those created from simulations and therefore enable us to derive interaction parameters from observed CW-CH interaction events that usually cannot be obtained directly. The simulation results in this study are augmented by analytical expressions for the reflection coefficient of the CW-CH interaction which allows us to verify the simulations results in an additional way. This work is the first of a series of studies aiming to finally reconstruct actual observed CW-CH interaction events by means of MHD-simulations.

Photometric metallicity formulae of fundamental-mode RR Lyr (RRab) stars are presented using globular-cluster data exclusively. The aim is to check whether this selection may help increasing the overall accuracy of the fits and eliminating the systematic bias of the photometric results, namely that they tend to overestimate [Fe/H] of the most metal-poor variables. The $G$-band time-series data available in the Gaia DR3 archive and a new compilation of the published spectroscopic globular cluster [Fe/H] values on a uniform solar reference metallicity scale are utilized. We have derived a new ${\mathrm{[Fe/H]}}_{\mathrm{phot}}- P,\varphi_{31}$ formula, and have diagnosed that no significant increase in the accuracy of the fit can be achieved using non-linear or multi-parameter formulae. The best result is obtained when different formulae are applied for variables with Oosterhoff-type I and II properties. However, even this solution cannot eliminate the systematic bias of the results completely. This separation of the variables has also led to the conclusion that the photometric estimates of the [Fe/H] are less reliable for the Oo-type II variables than for the Oo-type I sample. Published ${\mathrm{[Fe/H]}}_{\mathrm{phot}}$ values and the results of the available photometric formulae in the Gaia $G$-band are compared with the present results. It is found that each of the solutions yields very similar results, with similar accuracy and systematic biases. Major differences are detected only in the zero-points of the [Fe/H] scales, and these offsets are larger than differences in the accepted solar reference values would explain.

Our theoretical and numerical analysis have suggested that for low-mass main sequences stars (of the spectral classes from M5 to G0) rotating much faster than the sun, the generated large-scale magnetic field is caused by the mean-field $\alpha^2\Omega$ dynamo, whereby the $\alpha^2$ dynamo is modified by a weak differential rotation. Even for a weak differential rotation, the behaviour of the magnetic activity is changed drastically from aperiodic regime to nonlinear oscillations and appearance of a chaotic behaviour with increase of the differential rotation. Periods of the magnetic cycles decrease with increase of the differential rotation, and they vary from tens to thousand years. This long-term behaviour of the magnetic cycles may be related to the characteristic time of the evolution of the magnetic helicity density of the small-scale field. The performed analysis is based on the mean-field numerical simulations of the $\alpha^2\Omega$ and $\alpha^2$ dynamos and a developed nonlinear theory of $\alpha^2$ dynamo.

We present high angular-resolution observations of Sakurai's object using the Atacama Large Millimeter Array, shedding new light on its morpho-kinematical structure. The millimetre continuum emission, observed at an angular resolution of 20 milliarcsec (corresponding to 70 AU), reveals a bright compact central component whose spectral index indicates that it composed of amorphous carbon dust. Based on these findings, we conclude that this emission traces the previously suggested dust disc observed in mid-infrared observations. Therefore, our observations provide the first direct imaging of such a disc. The H$^{12}$CN($J$=4$\rightarrow$3) line emission, observed at an angular resolution of 300 milliarcsec (corresponding to 1000 AU), displays bipolar structure with a north-south velocity gradient. From the position-velocity diagram of this emission we identify the presence of an expanding disc and a bipolar molecular outflow. The inclination of the disc is determined to be $i$=72$^\circ$. The derived values for the de-projected expansion velocity and the radius of the disc are $v_{\rm exp}$=53 km s$^{-1}$ and $R$=277 AU, respectively. On the other hand, the de-projected expansion velocity of the bipolar outflow detected in the H$^{12}$CN($J$=4$\rightarrow$3) emission of approximately 1000 km s$^{-1}$. We propose that the molecular outflow has an hourglass morphology with an opening angle of around 60$^{\circ}$. Our observations unambiguously show that an equatorial disc and bipolar outflows formed in Sakurai's object in less than 30 years after the born-again event occurred, providing important constraints for future modelling efforts of this phenomenon.

The H.E.S.S. Galactic Plane Survey (HGPS), carried out between 2004 and 2013, is the most extensive survey of our Galaxy at very-high energies that covers the southern sky. Since the first HPGS catalogue release, the new observations accumulated provide a deeper scan of many Galactic sources, and a number of improvements have been made at various stages of the data processing chain, notably on events reconstruction and background modeling techniques. In parallel a new catalog production workflow has been tested and optimized on simulations done in preparation for the future Galactic Plane survey to be conducted by the Cherenkov Telescope Array (CTA). The development of a common data format and open scientific tools for gamma-ray astronomy allowed a smooth transition from the exploratory work done on CTA simulations to its application for H.E.S.S. data analysis. These elements offered a solid ground to build the second H.E.S.S. Galactic Plane Survey catalogue (2HGPS). In the following we will focus on the description of the catalogue workflow and show few results along the way.

We present an analysis of the ultra-violet (UV) observations of two Seyfert type active galactic nuclei (AGN), namely NGC$~$4051 and NGC$~$4151. These observations aimed at studying the star formation in the hosts of these AGN were carried out with the ultra-violet imaging telescope on board AstroSat in far-UV. A total of 193 and 328 star-forming regions (SF) were identified using SExtractor in NGC$~$4051 and NGC$~$4151, respectively. Using aperture photometry of the identified SF regions, we estimated the star formation rates (SFRs). We found NGC$~$4051 to have the lowest SFR with a median value of 3.16 $\times$ 10$^{-5}$ M$_{\odot}$ yr$^{-1}$ while for NGC$~$4151, we found a median SFR of 0.012 M$_{\odot}$ yr$^{-1}$.

Galaxy clusters are located at the nodes of cosmic filaments and therefore host a lot of hydrodynamical activity. However, cool core clusters are considered to be relatively relaxed systems without much merging activity. The Abell 85 cluster is a unique example where the cluster hosts both a cool core and multiple ongoing merging processes. In this work, we used 700 MHz uGMRT as well as MeerKAT L-band observations, carried out as part of the MGCLS, of the Abell 85. We reconfirm the presence of a minihalo in the cluster centre at 700MHz that was recently discovered in MGCLS. Furthermore, we discovered a radio bridge connecting the central minihalo and the peripheral radio phoenix. The mean surface brightness, size and flux density of the bridge at 700 MHz is found to be $\sim 0.14\ \mu$Jy/arcsec$^2$, $\sim 220$ kpc and $\sim 4.88$ mJy, respectively, with a spectral index of $\alpha_{700}^{1.28} = -0.92$. Although the origin of the seed relativistic electrons is still unknown, turbulent re-acceleration caused by both the spiralling sloshing gas in the intracluster medium (ICM) and the post-shock turbulence from the outgoing merging shock associated with the phoenix formation may be responsible for the bridge.

The recent announcement of strong evidence for a stochastic gravitational-wave background (SGWB) by various pulsar timing array collaborations has highlighted this signal as a promising candidate for future observations. Despite its non-detection by ground-based detectors such as Advanced LIGO and Advanced Virgo, Callister \textit{et al.}~\cite{tom_nongr_method} developed a Bayesian formalism to search for an isotropic SGWB with non-tensorial polarizations, imposing constraints on signal amplitude in those components that violate general relativity using LIGO's data. Since our ultimate aim is to estimate the spatial distribution of gravitational-wave sources, we have extended this existing method to allow for anisotropic components in signal models. We then examined the potential benefits from including these additional components. Using injection campaigns, we found that introducing anisotropic components into a signal model led to more significant identification of the signal itself and violations of general relativity. Moreover, the results of our Bayesian parameter estimation suggested that anisotropic components aid in breaking down degeneracies between different polarization components, allowing us to infer model parameters more precisely than through an isotropic analysis. In contrast, constraints on signal amplitude remained comparable in the absence of such a signal. Although these results might depend on the assumed source distribution on the sky, such as the Galactic plane, the formalism presented in this work has laid a foundation for establishing a generalized Bayesian analysis for an SGWB, including its anisotropies and non-tensorial polarizations.

We present \textit{JWST} images of the well-known planetary nebula NGC\,6720 (the Ring Nebula), covering wavelengths from 1.6$\mu$m to 25 $\mu$m. The bright shell is strongly fragmented with some 20\,000 dense globules, bright in H$_2$, with a characteristic diameter of 0.2~arcsec and density $n_{\rm H} \sim 10^5$--$10^6$\,cm$^{-3}$. The shell contains a thin ring of polycyclic aromatic hydrocarbon (PAH) emission. H$_2$ is found throughout the shell and in the halo. H$_2$ in the halo may be located on the swept-up walls of a biconal polar flow. The central cavity is shown to be filled with high ionization gas and shows two linear structures. The central star is located 2~arcsec from the emission centroid of the cavity and shell. Linear features (`spikes') extend outward from the ring, pointing away from the central star. Hydrodynamical simulations are shown which reproduce the clumping and possibly the spikes. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280~yr A previously known much wider companion is located at a projected separation of about 15\,000~au; we show that it is an M2--M4 dwarf. The system is therefore a triple star. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC\,3132) and may be a common aspect of such nebulae.

We present a study of the dust associated with the core-collapse supernova SN~1995N. Infrared emission detected 14--15 years after the explosion was previously attributed to thermally echoing circumstellar material associated with the SN progenitor. We argue that this late-time emission is unlikely to be an echo, and is more plausibly explained by newly formed dust in the supernova ejecta, indirectly heated by the interaction between the ejecta and the CSM. Further evidence in support of this scenario comes from emission line profiles in spectra obtained 22 years after the explosion; these are asymmetric, showing greater attenuation on the red wing, consistent with absorption by dust within the expanding ejecta. The spectral energy distribution and emission line profiles at epochs later than $\sim$5000 days are both consistent with the presence of about 0.4~M$_\odot$ of amorphous carbon dust. The onset of dust formation is apparent in archival optical spectra, taken between 700 and 1700 days after the assumed explosion date. As this is considerably later than most other instances where the onset of dust formation has been detected, we argue that the explosion date must be later than previously assumed.

According to Einstein's special relativity theory, the speed of light in a vacuum is constant for all observers. However, quantum gravity effects could introduce its dispersion depending on the energy of photons. The investigation of the spectral lags between the gamma-ray burst (GRB) light curves recorded in distinct energy ranges could shed light on this phenomenon: the lags could reflect the variation of the speed of light if it is linearly dependent on the photon energy and a function of the GRB redshift. We propose a methodology to start investigating the dispersion law of light propagation in a vacuum using GRB light curves. This technique is intended to be fully exploited using the GRB data collected with THESEUS.

A recent study shows, from an empirical deduction, that the number and the presence of the blue straggler stars (BSS) in an open cluster follow a function whose components are the ratio between age and the relaxation time, $\it f$, and a factor, $\varpi$ , which is an indicator of stellar collisions plus primordial binaries. The relation among the number of blue straggler stars, the factor $\it f$, and the factor $\varpi$ of each globular cluster allows for deriving the age of the respective globular clusters. This method has been applied individually over 56 globular clusters containing BSS. The values derived for the cluster ages from our methodology do not differ from those derived from other methods. A special case is cluster NGC 104 whose age exceeds 13.8 Gyr (its age is between 19.04 and 20.30 Gyr), which would have a very exotic explanation: the existence of an intermediate black hole in the center of the cluster. That black hole main-sequence star (BH-MS) binaries with an initial orbital period less than the bifurcation period can evolve into ultra-compact X-ray binaries (UCXBs) that can be detected by LISA. On the other hand, if that age were true, it would call into question the expansion velocity for a flat Universe. This would call into question the case for dark energy dominated Universe.

The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera 3 Ultraviolet and Visible light F275W imaging with coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We introduce this survey by presenting a thorough search for galaxies at $z\gtrsim2.4$ that leak significant Lyman continuum (LyC) radiation, as well as a stringent constraint on the LyC escape fraction ($f_{\rm esc}$) from stacking the UV images of a population of star-forming galaxies with secure redshifts. Our extensive search for LyC emission and stacking analysis benefit from the catalogs of high-quality spectroscopic redshifts compiled from archival ground-based data and HST slitless spectroscopy, carefully vetted by dedicated visual inspection efforts. We report a sample of five galaxies as individual LyC leaker candidates, showing $f_{\rm esc}^{\rm rel}\gtrsim60\%$ estimated using detailed Monte Carlo analysis of intergalactic medium attenuation. We develop a robust stacking method to apply to five samples of in total 85 non-detection galaxies in the redshift range of $z\in[2.4,3.7]$. Most stacks give tight 2-$\sigma$ upper limits below $f_{\rm esc}^{\rm rel}<6\%$. A stack for a subset of 32 emission-line galaxies shows tentative LyC leakage detected at 2.9-$\sigma$, indicating $f_{\rm esc}^{\rm rel}=5.7\%$ at $z\sim2.65$, supporting the key role of such galaxies in contributing to the cosmic reionization and maintaining the UV ionization background. These new F275W and F435W imaging mosaics from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes.

This invited memoir looks back on my scientific career that straddles the solar and stellar branches of astrophysics, with sprinklings of historical context and personal opinion. Except for a description of my life up to my Ph.D. phase, the structure is thematic rather than purely chronological, focusing on those topics that I worked on throughout substantial parts of my life: stars like the Sun and the Sun-as-a-star, surface field evolution, coronal structure and dynamics, heliophysics education, and space weather. Luck and a broadly inquisitive frame of mind shaped a fortunate life on two continents, taking me from one amazing mentor, colleague, and friend to another, working in stimulating settings to interpret data from state-of-the-art space observatories.

We analyze 347 galaxies at redshift $4<z<9.5$ using JWST observations from the CEERS program by fitting a two-dimensional parametric model simultaneously to the seven-filter NIRCam images to measure the overall structural parameters and quantify the global properties of the galaxies in the rest-frame optical band. Particular attention is devoted to deriving robust uncertainties that include, among other factors, the influence of cosmological surface brightness dimming and resolution effects. Using the global S\'ersic index ($n < 1.5$) and observed axial ratio ($q < 0.6$) as a guide, we place a conservative lower limit of $\sim 45\%$ on the incidence of galactic disks. Galaxies follow a relation between rest-frame optical luminosity and effective radius in the redshift range $4<z<9.5$, as well as separately over the intervals $4 < z < 5$ and $5 \leq z < 9.5$, with a very similar slope but a marginally lower zero point in the higher redshift bin ($R_e = 0.49 \pm 0.07$ kpc) compared to the lower redshift bin ($R_e = 0.65 \pm 0.12$ kpc). Within the limitations of the current sample size, we find no significant redshift evolution of $n$ or $R_e$ at these early epochs.

We use a 0.7-m telescope in the framework of the Halos and Environments of Nearby Galaxies (HERON) survey to probe low surface brightness structures in nearby galaxies. One of our targets, UGC 4599, is usually classified as an early-type galaxy surrounded by a blue ring making it a potential Hoag's Object analog. Prior photometric studies of UGC 4599 were focused on its bright core and the blue ring. However, the HERON survey allows us to study its faint extended regions. With an eight hour integration, we detect an extremely faint outer disk with an extrapolated central surface brightness of $\mu_\mathrm{0,d}(r)=25.5$ mag arcsec$^{-2}$ down to 31 mag arcsec$^{-2}$ and a scale length of 15 kpc. We identify two distinct spiral arms of pitch angle ~6{\deg} surrounding the ring. The spiral arms are detected out to ~45 kpc in radius and the faint disk continues to ~70 kpc. These features are also seen in the GALEX FUV and NUV bands, in a deep u-band image from the 4.3m Lowell Discovery Telescope (which reveals inner spiral structure emerging from the core), and in HI. We compare this galaxy to ordinary spiral and elliptical galaxies, giant low surface brightness (GLSB) galaxies, and Hoag's Object itself using several standard galaxy scaling relations. We conclude that the pseudobulge and disk properties of UGC 4599 significantly differ from those of Hoag's Object and of normal galaxies, pointing toward a GLSB galaxy nature and filamentary accretion of gas to generate its outer disk.

In the presence of (relatively) long-range forces, structures can form even during the radiation dominated era, leading to compact objects, such as Fermi balls or primordial black holes (PBH), which can account for all or part of dark matter. We present a detailed analysis of a model in which fermions are produced from the inflaton decay developing some particle-antiparticle asymmetry. These fermions undergo clustering and structure formation driven by a Yukawa interaction. The same interaction provides a cooling channel for the dark halos via scalar radiation, leading to rapid collapse and the formation of a compact object. We discuss the criteria for the formation of either PBHs and Fermi balls. In the PBH formation regime, supermassive PBHs can seed the active galactic nuclei or quasars found at high redshift. Alternatively, Fermi balls can account for all of the cold dark matter, while evading microlensing constraints.

The Active Galatic Nuclei(AGN) disk has been proposed as a potential channel for the merger of binary black holes. The population of massive stars and black holes in AGN disks captured from the nuclei cluster plays a crucial role in determining the efficiency of binary formation and final merger rate within the AGN disks. In this paper, we investigate the capture process using analytical and numerical approaches. We discover a new constant integral of motion for one object's capture process. {Applying this result to the whole population of the nuclei cluster captured by the AGN disk, we find that the population of captured objects} depends on the angular density and eccentricity distribution of the nuclei clusters and is effectively independent of the radial density profile of the nuclei cluster and disk models. An isotropic nuclei cluster with thermal eccentricity distribution predicts a captured profile $\dd N/\dd r\propto r^{-1/4}$. The captured objects are found to be dynamically crowded within the disk. Direct binary formation right after the capture would be promising, especially for stars. The conventional migration traps that help pile up single objects in AGN disks for black hole mergers might not be required.

Off-centred dipole configurations have been suggested to explain different phenomena in neutron stars, such as natal kicks, irregularities in polarisation of radio pulsars and properties of X-ray emission from millisecond pulsars. Here for the first time we model magneto-thermal evolution of neutron stars with crust-confined magnetic fields and off-centred dipole moments. We find that the dipole shift decays with time if the initial configuration has no toroidal magnetic field. The decay timescale is inversely proportional to magnetic field. The octupole moment decreases much faster than the quadrupole. Alternatively, if the initial condition includes strong dipolar toroidal magnetic field, the external poloidal magnetic field evolves from centred dipole to off-centred dipole. The surface thermal maps are very different for configurations with weak $B = 10^{13}$ G and strong $B = 10^{14}$ G magnetic fields. In the former case, the magnetic equator is cold while in the latter case it is hot. We model lightcurves and spectra of our magneto-thermal configurations. We found that in the case of cold equator, the pulsed fraction is small (below a few percent in most cases) and spectra are well described with a single blackbody. Under the same conditions models with stronger magnetic fields produce lightcurves with pulsed fraction of tens of percent. Their spectra are significantly better described with two blackbodies. Overall, the magnetic field strength has a more significant effect on bulk thermal emission of neutron stars than does the field geometry.

Kilonovae are optical transients following the merger of neutron star binaries, which are powered by the r-process heating of merger ejecta. However, if a merger remnant is a long-living supramassive neutron star supported by its uniform rotation, it will inject energy into the ejecta through spindown power. The energy injection can boost the peak luminosity of a kilonova by many orders of magnitudes, thus significantly increasing the detectable volume. Therefore, even if such events are only a small fraction of the kilonovae population, they could dominate the detection rates. However, after many years of optical sky surveys, no such event has been confirmed. In this work, we build a boosted kilonova model with rich physical details, including the description of the evolution and stability of a proto neutron star, and the energy absorption through X-ray photoionization. We simulate the observation prospects and find the only way to match the absence of detection is to limit the energy injection by the newly born magnetar to only a small fraction of the neutron star rotational energy, thus they should collapse soon after the merger. Our result indicates that most supramassive neutron stars resulting from binary neutron star mergers are short lived and they must be rare in the universe.

Context. Current constraints on distributed matter in the innermost Galactic Centre (such as a cluster of faint stars and stellar remnants, Dark Matter or a combination thereof) based on the orbital dynamics of the visible stars closest to the central black hole, typically assume simple functional forms for the distributions. Aims. We take instead a general model agnostic approach in which the form of the distribution is not constrained by prior assumptions on the physical composition of the matter. This approach yields unbiased - entirely observation driven - fits for the matter distribution and places constraints on our ability to discriminate between different density profiles (and consequently between physical compositions) of the distributed matter. Methods. We construct a spherical shell model with the flexibility to fit a wide variety of physically reasonable density profiles by modelling the distribution as a series of concentric mass shells. We test this approach in an analysis of mock observations of the star S2. Results. For a sufficiently large and precise data set, we find that it is possible to discriminate between several physically motivated density profiles. However, for data coming from current and expected next generation observational instruments, the potential for profile distinction will remain limited by the precision of the instruments. Future observations will still be able to constrain the overall enclosed distributed mass within the apocentre of the probing orbit in an unbiased manner. We interpret this in the theoretical context of constraining the secular versus non-secular orbital dynamics.

Supernovae are an important source of energy in the interstellar medium. Young remnants of supernovae have a peak emission in the X-ray region, making them interesting objects for X-ray observations. In particular, the supernova remnant SN1006 is of great interest due to its historical record, proximity and brightness. It has therefore been studied by several X-ray telescopes. Improving the X-ray imaging of this and other remnants is important but challenging as it requires to address a spatially varying instrument response in order to achieve a high signal-to-noise ratio. Here, we use Chandra observations to demonstrate the capabilities of Bayesian image reconstruction using information field theory. Our objective is to reconstruct denoised, deconvolved and spatio-spectral resolved images from X-ray observations and to decompose the emission into different morphologies, namely diffuse and point-like. Further, we aim to fuse data from different detectors and pointings into a mosaic and quantify the uncertainty of our result. Utilizing prior knowledge on the spatial and spectral correlation structure of the two components, diffuse emission and point sources, the presented method allows the effective decomposition of the signal into these. In order to accelerate the imaging process, we introduce a multi-step approach, in which the spatial reconstruction obtained for a single energy range is used to derive an informed starting point for the full spatio-spectral reconstruction. The method is applied to 11 Chandra observations of SN1006 from 2008 and 2012, providing a detailed, denoised and decomposed view of the remnant. In particular, the separated view of the diffuse emission should provide new insights into its complex small-scale structures in the center of the remnant and at the shock front profiles.

We have compiled a sample of 67 nearby ($z$ < 0.15) clusters of galaxies, for which on average more than 150 spectroscopic members are available, and, by applying different methods to detect substructures in their galaxy distribution, we have studied their assembly history. Our analysis confirms that substructures are present in 70% of our sample, having a significant dynamical impact in 57% of them. A classification of the assembly state of the clusters based on the dynamical significance of their substructures is proposed. In 19% of our clusters, the originally identified brightest cluster galaxy is not the central gravitationally dominant galaxy (CDG), but turns out to be either the second-rank, or the dominant galaxy of a substructure (a SDG, in our classification), or even a possible "fossil" galaxy in the periphery of the cluster. Moreover, no correlation was found in general between the projected offset of the CDG from the X-ray peak and its peculiar velocity. The comparison of the CDGs properties with the assembly states and dynamical state of the intracluster media, especially the core cooling status, suggests a complex assembly history, with clear evidence of co-evolution of the CDG and its host cluster in the innermost regions.

Detector commanding, processing and readout of spaceborne instrumentation is often accomplished with Application Specific Integrated Circuits (ASICs). The ASIC designed for the Nuclear Spectroscopic Telescope Array (NuSTAR) mission (NuASIC) enables future tiled CdZnTe (CZT) detector array readout for x-ray detectors such as the High Resolution Energetic X-ray Imager (HREXI). Modified NuASIC gain settings have been implemented for HREXI's broader targeted imaging energy range (3-300 keV) compared to NuSTAR (2-79 keV), which may require updated NuASIC internal parameters for optimal energy resolution. To reach HREXI's targeted low energy threshold, we have also enabled the NuASIC's "Charge Pump Mode" (CPM), which introduces an additional tuning parameter. In this paper, we describe the mechanics of the NuASIC's adjustable parameters and use our recently developed ASIC Test Stand (ATS) to probe a "bare" NuASIC using its internal test pulser. We record the effects of parameter tuning on the device's electronics noise and low energy threshold and report the optimal set of parameters for HREXI's updated gain setting. We detail a semi-automated procedure to derive the optimal parameters for each of HREXI's large area, closely tiled NuASIC/CZT detectors to expedite instrument integration.

Over a dozen transiting circumbinary planets have been discovered around eclipsing binaries. Transit detections are biased towards aligned planet and binary orbits, and indeed all of the known planets have mutual inclinations less than $4.5^{\circ}$. One path to discovering circumbinary planets with misaligned orbits is through eclipse timing variations (ETVs) of non-transiting planets. Borkovits et al. (2016) discovered ETVs on the 18.6 d binary Kepler-1660AB, indicative of a third body on a $\approx 236$ d period, with a misaligned orbit and a potentially planetary mass. Getley et al. (2017) agreed with the planetary hypothesis, arguing for a $7.7M_{\rm Jup}$ circumbinary planet on an orbit that is highly misaligned by $120^{\circ}$ with respect to the binary. In this paper, we obtain the first radial velocities of the binary. We combine these with an analysis of not only the ETVs but also the eclipse depth variations. We confirm the existence of a $239.5$ d circumbinary planet, but with a lower mass of $4.87M_{\rm Jup}$ and a coplanar orbit. The misaligned orbits proposed by previous authors are definitively ruled out by a lack of eclipse depth variations. Kepler-1660ABb is the first confirmed circumbinary planet found using ETVs around a main sequence binary.

The low-energy gamma-ray (0.1-30 MeV) sky has been poorly observed since the decommissioning of the COMPTEL instrument on board the Compton Gamma-ray Observer (CGRO) satellite in 2000. The study of photons from this energy band (the MeV "gap") is, however, crucial to answer many unsolved questions in high-energy and multi-messenger astrophysics. Although several MeV gamma-ray missions have been proposed (e.g. AMEGO, e-ASTROGAM), these are mostly in the planning phase, and their launch is not expected until the next decade, at the earliest. Recently, there has been a proliferation of CubeSat missions proposed as "pathfinder" alternatives due to their low cost and faster cycles of implementation. Indeed, a MeV CubeSat for gamma-ray astronomy can be a suitable demonstrator for future, larger-scale MeV payloads. In this paper, a gamma-ray payload design with a silicon tracker and CsI calorimeter is proposed. We report the results of simulations to assess the performance of this payload possibility and compare these with other previous gamma-ray instruments.

We consider the production of secondary gravity waves in Galileon inflation with an ultra-slow roll (USR) phase and show that the spectrum of scalar-induced gravitational waves (SIGWs) in this case is consistent with the recent NANOGrav 15-year data and with sensitivities of other ground and space-based missions, LISA, BBO, DECIGO, CE, ET, HLVK (consists of aLIGO, aVirgo, and KAGRA), and HLV(03). Thanks to the non-renormalization property of Galileon theory, the amplitude of the large fluctuation is controllable at the sharp transitions between SR and USR regions. We show that the behaviour of the GW spectrum, when one-loop effects are included in the scalar power spectrum, is preserved under a shift of the sharp transition scale with peak amplitude $\Omega_{\rm GW}h^2\sim {\cal O}(10^{-6})$, and hence it can cover a wide range of frequencies within ${\cal O}(10^{-9}{\rm Hz} - 10^{7}{\rm Hz})$. An analysis of the allowed mass range for primordial black holes (PBHs) is also performed, where we find that mass values ranging from ${\cal O}(1M_{\odot} - 10^{-18}M_{\odot})$ can be generated over the corresponding allowed range of low and high frequencies.

A catalog of the Galactic population of X-ray pulsars in high-mass X-ray binary (HMXB) systems is presented. It contains information about 82 confirmed sources: 18 persistent and 64 transient pulsars. Their basic parameters include spin period, spin evolution with global and local spin-up/spin-down and duration, orbital period, X-ray luminosity, magnetic field strength measured by cyclotron line analysis, distance, spectral and luminosity class, observable parameters of massive companions, which are shown in the tables provided, with corresponding references. Candidates of the HMXB pulsars are also listed for further careful consideration.

We present an analysis of the effects of uncertainties in the atmosphere models on the radius, mass, and other neutron star parameter constraints for the NICER observations of rotation-powered millisecond pulsars. To date, NICER has applied the X-ray pulse profile modeling technique to two millisecond-period pulsars: PSR J0030+0451 and the high-mass pulsar PSR J0740+6620. These studies have commonly assumed a deep-heated fully-ionized hydrogen atmosphere model, although they have explored the effects of partial-ionization and helium composition in some cases. Here we extend that exploration and also include new models with partially ionized carbon composition, externally heated hydrogen, and an empirical atmospheric beaming parametrization to explore deviations in the expected anisotropy of the emitted radiation. None of the studied atmosphere cases have any significant influence on the inferred radius of PSR J0740+6620, possibly due to its X-ray faintness, tighter external constraints, and/or viewing geometry. In the case of PSR J0030+0451 both the composition and ionization state could significantly alter the inferred radius. However, based on the evidence (prior predictive probability of the data), partially ionized hydrogen and carbon atmospheres are disfavored. The difference in the evidence for ionized hydrogen and helium atmospheres is too small to be decisive for most cases, but the inferred radius for helium models trends to larger sizes around or above 14-15 km. External heating or deviations in the beaming that are less than $5\,\%$ at emission angles smaller than 60 degrees, on the other hand, have no significant effect on the inferred radius.

The future Laser Interferometer Space Antenna (LISA) mission, which has successfully passed Mission Formulation phase, is in planning to be launched in 2030s. One of the ubiquitous LISA sources are the white-dwarf binaries (WDB) of which $\sim$40 are guaranteed sources as of now, making LISA unique in comparison to its ground-based counterpart. The current hardware design in planning necessitates a thorough check to determine whether the various locking schemes influence the guaranteed sources' signals significantly in order to re-consider that what is hard-coded in the phasemeter before launch for pre-science operations phase. Comparison of the phasemeter output of a face-on (V407Vul) binary and an edge-on (ZTFJ1539) binary indicates that the non-swap locking scheme, N2a, is optimal for instrument calibration. Additionally, the influence of the $\sim 7$ min orbital period edge-on source in two of the locking schemes yields a difference of maximum $\leq 10\%$ at the Time Delay Interferometry (TDI) output for data stream of one day. Simplified analyses show that neither of the locking schemes is favoured in the post-processing level. We find similar amplitudes in the TDI output stream for the face-on system V407Vul and the edge-on system ZTFJ1539 which leads to a significantly smaller inclination bias for the non-swap locking scheme. Additionally, a larger amplitude for edge-on systems will benefit most verification systems as the population of verification systems is biased towards edge-on systems as they are easier to detect in electromagnetic data.

With its immensity and numerous mysteries waiting to be solved, the cosmos has always captivated humankind. A ground-breaking field that has given us a profound understanding of the mysteries of the cosmos is radio astronomy. This paper presents a comprehensive overview of radio astronomy, exploring its techniques, discoveries, and the profound insights it offers into celestial objects. Radio astronomy, which uses radio waves to analyse celestial phenomena, has completely changed how we think about the universe. This field has given us crucial information about the formation of stars, galaxies, and other celestial objects through the analysis of radio emissions. Radio astronomy has enabled researchers to study cosmic processes that are undetectable to the human eye by penetrating the furthest reaches of space. We explore radio astronomy techniques in this article, revealing how it can be used to see through interstellar dust and collect signals from the universe's furthest reaches. Pulsars, quasars, and cosmic microwave background radiation are significant discoveries that have helped astronomers understand dark matter and dark energy in great detail. We also look into how radio astronomy might be used in cosmology and astrophysics. In conclusion, radio astronomy has become a potent tool for solving the cosmos' riddles. Its capacity for the detection and analysis of radio emissions has produced a fundamental understanding of the beginnings and evolution of the universe. Radio astronomy continues to advance our understanding of the cosmos and arouses interest in additional cosmic research by shedding light on celestial objects that are invisible to the human eye.

The IceCube Neutrino Observatory, a cubic-kilometer-scale neutrino detector at the geographic South Pole, has reached a number of milestones in the field of neutrino astrophysics: the discovery of a high-energy astrophysical neutrino flux, the temporal and directional correlation of neutrinos with a flaring blazar, and a steady emission of neutrinos from the direction of an active galaxy of a Seyfert II type and the Milky Way. The next generation neutrino telescope, IceCube-Gen2, currently under development, will consist of three essential components: an array of about 10,000 optical sensors, embedded within approximately 8 cubic kilometers of ice, for detecting neutrinos with energies of TeV and above, with a sensitivity five times greater than that of IceCube; a surface array with scintillation panels and radio antennas targeting air showers; and buried radio antennas distributed over an area of more than 400 square kilometers to significantly enhance the sensitivity of detecting neutrino sources beyond EeV. This contribution describes the design and status of IceCube-Gen2 and discusses the expected sensitivity from the simulations of the optical, surface, and radio components.

Numerous delta Sct and gamma Dor pulsators are identified in the region of the Hertzsprung-Russell diagram that is occupied by chemically peculiar magnetic Ap stars. The connection between delta Sct and gamma Dor pulsations and the magnetic field in Ap stars is however not clear: theory suggests for magnetic Ap stars some critical field strengths for pulsation mode suppression by computing the magnetic damping effect for selected p and g modes. To test these theoretical considerations, we obtained PEPSI spectropolarimetric snapshots of the typical Ap star HD340577, for which delta Sct-like pulsations were recently detected in TESS data, and the gamma Dor pulsator HR8799, which is a remarkable system with multiple planets and two debris disks. Our measurements reveal the presence of a magnetic field with a strength of several hundred Gauss in HD340577. The measured mean longitudinal field would be the strongest field measured so far in a delta Sct star if the pulsational character of HD340577 is confirmed spectroscopically. No magnetic field is detected in HR8799.

The detection of large angular scale $B$-mode in the Cosmic Microwave Background (CMB) polarization signal will open a direct window into not only the primary CMB anisotropies caused by the primordial gravitational waves (PGW) originating in the epoch of inflation, but also the secondary anisotropies imprinted during the epoch of cosmic reionization. The existence of patchiness in the electron density during reionization produces a unique distortion in the CMB $B$-mode polarization, which can be distinguished from the PGW signal with the aid of spatial frequency modes. In this work, we employ an $EB$ estimator by combining $E$-mode and $B$-mode polarization for the $\tau$ power spectrum signal generated in a photon-conserving semi-numerical reionization model called SCRIPT. We developed a Bayesian framework for the joint detection of the PGW and reionization signal from CMB observations and show the efficacy of this technique for upcoming CMB experiments. We find that, for our model, the $\tau$ power spectrum signal effectively tracks the inhomogeneous electron density field, allowing for robust constraints on the patchy $B$-mode signal. Further, our results indicate that employing the $EB$ estimator for the $\tau$ signal will facilitate ground-based CMB-S4 to detect the patchy $B$-mode signal at approximately $\geq 2\sigma$ confidence level while observations with space-based PICO will improve this detection to $\geq 3\sigma$ going as high as $\geq 7\sigma$ for extreme reionization models. These findings not only highlight the future potential of these experiments to provide an improved picture of the reionization process but also have important implications towards an unbiased measurement of $r$.

We report the first detection of SiC$_2$ in the interstellar medium. The molecule was identified through six rotational transitions toward G\,+0.693$-$0.027, a molecular cloud located in the Galactic center. The detection is based on a line survey carried out with the GBT, the Yebes 40m, and the IRAM 30m telescopes covering a range of frequencies from 12 to 276 GHz. We fit the observed spectra assuming local thermodynamic equilibrium and derive a column density of ($1.02\pm0.04)\times10^{13}$ cm$^{-2}$, which gives a fractional abundance of $7.5\times10^{-11}$ with respect to H$_2$, and an excitation temperature of $5.9\pm0.2$ K. We conclude that SiC$_2$ can be formed in the shocked gas by a reaction between the sputtered atomic silicon and C$_2$H$_2$, or it can be released directly from the dust grains due to disruption. We also search for other Si-bearing molecules and detect eight rotational transitions of SiS and four transitions of Si$^{18}$O. The derived fractional abundances are $3.9\times10^{-10}$ and $2.1\times10^{-11}$, respectively. All Si-bearing species toward G\,+0.693$-$0.027 show fractional abundances well below what is typically found in late-type evolved stars.

In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterising dense matter. Two independent analyses found a mass of $\sim 1.3-1.4\,\mathrm{M_\odot}$ and a radius of $\sim 13\,$km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyse, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and jointly analyse also XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multi-modal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding constraints disfavors the main solutions found previously, in favor of the new and more complex models. These have inferred masses and radii of $\sim [1.4 \mathrm{M_\odot}, 11.5$ km] and $\sim [1.7 \mathrm{M_\odot}, 14.5$ km], depending on the assumed model. They display configurations that do not require the two hot spots generating the observed X-rays to be on the same hemisphere, nor to show very elongated features, and point instead to the presence of temperature gradients and the need to account for them.

The availability of simultaneous X-ray and Very High Energy (VHE) observations of blazars helps to identify the plausible radiative contributors to the VHE emission. Under leptonic scenario, the VHE emission from BL Lacs are attributed to the synchrotron self Compton (SSC) emission. However, many BL Lacerate (BL Lacs) have shown significant hardening at VHE after correction for the Extra Galactic Background Light (EBL) attenuation. We study the spectral hardening of two nearby BL Lac objects, Mkn 421 and Mkn 501 having most number of simultaneous X-ray and VHE observations available among all the blazars. These BL Lacs are relatively close and the effect of EBL attenuation is relatively minimal/negligible. We study the scatter plot between the X-ray spectral indices and intrinsic VHE indices to identify the plausible origin of the VHE emission. For Mkn 501, the VHE spectral indices are steeper than X-ray spectra, suggesting the scattering process happening at extreme Klein-Nishina regime. On the other hand, for Mkn 421, the VHE spectra is remarkably harder than the X-ray spectra, which suggests an additional emission mechanism other than the SSC process. We show this hard VHE spectrum of Mkn 421 can be explained by considering the inverse Compton (IC) emission from a broken power law electron distribution with Maxwellian pileup. The possibility of the hadronic contribution at VHE {\gamma}-rays is also explored by modeling the hard spectrum under photomeson process.

Aims. The main goal of the present paper is to provide the first systematic numerical study of the propagation of astrophysical relativistic jets, in the context of high-resolution shock-capturing resistive relativistic magnetohydrodynamics (RRMHD) simulations. We aim at investigating different values and models for the plasma resistivity coefficient, and at assessing their impact on the level of turbulence, the formation of current sheets and reconnection plasmoids, the electromagnetic energy content, and the dissipated power. Methods. We use the PLUTO code for simulations and we assume an axisymmetric setup for jets, endowed with both poloidal and toroidal magnetic fields, and propagating in a uniform magnetized medium. The gas is assumed to be characterized by a realistic Synge-like equation of state (Taub equation), appropriate for such type of astrophysical jets. The Taub equation is combined here for the first time with the Implicit-Explicit Runge-Kutta time-stepping procedure, as required in RRMHD simulations. Results. The main result is that turbulence is clearly suppressed for the highest values of resistivity (low Lundquist numbers), current sheets are broader, and plasmoids are barely present, while for low values of resistivity results are very similar to ideal runs, where dissipation is purely numerical. We find that recipes employing a variable resistivity based on the advection of a jet tracer or on the assumption of a uniform Lundquist number improve on the use of a constant coefficient and are probably more realistic, preserving the development of turbulence and of sharp current sheets, possible sites for the acceleration of the non-thermal particles producing the observed high-energy emission.

Turbulence plays a key role for forming the complex geometry of the large-scale current sheet (CS) and fast energy release in a solar eruption. In this paper, we present full 3D high-resolution simulations for the process of a moderate Coronal Mass Ejection (CME) and the thermodynamical evolution of the highly confined CS. Copious elongated blobs are generated due to tearing and plasmoid instabilities giving rise to a higher reconnection rate and undergo the splitting, merging and kinking processes in a more complex way in 3D. A detailed thermodynamical analysis shows that the CS is mainly heated by adiabatic and numerical viscous terms, and thermal conduction is the dominant factor that balances the energy inside the CS. Accordingly, the temperature of the CS reaches to a maximum of about 20 MK and the range of temperatures is relatively narrow. From the face-on view in the synthetic Atmospheric Imaging Assembly 131 $\mathring{A}$, the downflowing structures with similar morphology to supra-arcade downflows are mainly located between the post-flare loops and loop-top, while moving blobs can extend spikes higher above the loop-top. The downward-moving plasmoids can keep the twisted magnetic field configuration until the annihilation at the flare loop-top, indicating that plasmoid reconnection dominates in the lower CS. Meanwhile, the upward-moving ones turn into turbulent structures before arriving at the bottom of the CME, implying that turbulent reconnection dominates in the upper CS. The spatial distributions of the turbulent energy and anisotropy are addressed, which show a significant variation in the spectra with height.

From core to atmosphere, the oxidation states of elements in a planet shape its character. Oxygen fugacity (fO$_2$) is one parameter indicating these likely oxidation states. The ongoing search for atmospheres on rocky exoplanets benefits from understanding the plausible variety of their compositions, which depends strongly on their oxidation states -- and if derived from interior outgassing, on the fO$_2$ at the top of their silicate mantles. This fO$_2$ must vary across compositionally-diverse exoplanets, but for a given planet its value is unconstrained insofar as it depends on how iron (the dominant multivalent element) is partitioned between its 2+ and 3+ oxidation states. Here we focus on another factor influencing how oxidising a mantle is -- a factor modulating fO$_2$ even at fixed Fe$^{3+}$/Fe$^{2+}$ -- the planet's mineralogy. Only certain minerals (e.g., pyroxenes) incorporate Fe$^{3+}$. Having such minerals in smaller mantle proportions concentrates Fe$^{3+}$, increasing fO$_2$. Mineral proportions change within planets according to pressure, and between planets according to bulk composition. Constrained by observed host star refractory abundances, we calculate a minimum fO$_2$ variability across exoplanet mantles, of at least two orders of magnitude, due to mineralogy alone. This variability is enough to alter by a hundredfold the mixing ratio of SO$_2$ directly outgassed from these mantles. We further predict that planets orbiting high-Mg/Si stars are more likely to outgas detectable amounts of SO$_2$ and H$_2$O; and for low-Mg/Si stars, detectable CH$_4$, all else equal. Even absent predictions of Fe$^{3+}$ budgets, general insights can be obtained into how oxidising an exoplanet's mantle is.

Operating mechanical devices in low earth orbit (LEO) environment presents unique challenges due to adverse effects of the LEO environment on lubricants and materials in tribo-mechanisms. These challenges include corrosion due to atomic oxygen, molecular degradation of materials and fluids due to radiation, temperature extremes influencing lubricant viscosity, and rapid evaporative loss of fluids in vacuum conditions. Therefore, lubricants for mechanisms and components such as bearings and gears for spacecraft should be tested extensively in both air and vacuum to ensure their continuous and accurate function. Literature on ground based tribo-testing is extensive and well-established. However, tribological investigations conducted in LEO are much fewer in number. The purpose of this paper is to draw together details of tribology experiments of this type, to try to clarify their purpose and value. This review presents these studies according to a thematic categorization of the mechanisms involved.

We present a new energy transport code that models the time dependent and non-linear evolution of spectra of cosmic-ray nuclei, their secondaries, and photon target fields. The software can inject an arbitrary chemical composition including heavy elements up to iron nuclei. Energy losses and secondary production due to interactions of cosmic ray nuclei, secondary mesons, leptons, or gamma-rays with a target photon field are available for all relevant processes, e.g., photo-meson production, photo disintegration, synchrotron radiation, Inverse Compton scattering, and more. The resulting x-ray fluxes can be fed back into the simulation chain to correct the initial photon targets, resulting in a non-linear treatment of the energy transport. The modular structure of the code facilitates simple extension of interaction or target field models. We will show how the software can be used to improve predictions of observables in various astrophysical sources such as jetted active galactic nuclei (AGN). Since the software can model the propagation of heavy ultrahigh-energy cosmic rays inside the source it can precisely predict the chemical composition at the source. This will also refine predictions of neutrino emissions - they strongly depend on the chemical composition. This helps in the future to optimize the selection and analyses of data from the IceCube neutrino observatory with the aim to enhance the sensitivity of IceCube and reduce the number of trial factors.

CRPropa is a Monte Carlo framework for simulating the propagation of (ultra-) high-energy particles in the Universe, including cosmic rays, gamma rays, electrons, and neutrinos. It covers energies from ZeV down to GeV for gamma rays and electrons, and TeV for cosmic rays and neutrinos, supporting various astrophysical environments such as the surroundings of astrophysical sources, galactic, and extragalactic environments. The newest version, CRPropa 3.2, represents a significant leap forward towards a universal multi-messenger framework, opening up the possibility for many more astrophysical applications. This includes extensions to simulate cosmic-ray acceleration and particle interactions within astrophysical source environments, a full Monte Carlo treatment of electromagnetic cascades, improved ensemble-averaged Galactic propagation, significant performance improvements for cosmic-ray tracking through magnetic fields, and a user-friendly implementation of custom photon fields, among many more enhancements. This contribution will give an overview of the new features and present several applications to cosmic-ray and gamma-ray propagation.

PDS 70 is so far the only young disc where multiple planets have been detected by direct imaging. The disc has a large cavity when seen at sub-mm and NIR wavelengths, which hosts two massive planets. This makes PDS 70 the ideal target to study the physical conditions in a strongly depleted inner disc shaped by two giant planets, and in particular to test whether disc winds can play a significant role in its evolution. Using X-Shooter and HARPS spectra, we detected for the first time the wind-tracing [O I] 6300AA line, and confirm the low-moderate value of mass-accretion rate in the literature. The [O I] line luminosity is high with respect to the accretion luminosity when compared to a large sample of discs with cavities in nearby star-forming regions. The FWHM and blue-shifted peak of the [O I] line suggest an emission in a region very close to the star, favouring a magnetically driven wind as the origin. We also detect wind emission and high variability in the He I 10830AA line, which is unusual for low-accretors. We discuss that, although the cavity of PDS 70 was clearly carved out by the giant planets, the substantial inner disc wind could also have had a significant contribution to clearing the inner-disc.

(Abridged) There is a diverse chemical inventory in protostellar regions leading to the classification of extreme types of systems. Warm carbon chain chemistry sources, for one, are the warm and dense regions near a protostar containing unsaturated carbon chain molecules. Since the presentation of this definition in 2008, there is a growing field to detect and characterise these sources. The details are lesser known in relation to hot cores and in high-mass star-forming regions -- regions of great importance in galactic evolution. To investigate the prevalence of carbon chain species and their environment in high-mass star-forming regions, we have conducted targeted spectral surveys of two sources in the direction of Cygnus X -- AFGL 2591 and IRAS 20126+4104 -- with the Green Bank Telescope and the IRAM 30m Telescope. We have constructed a Local Thermodynamic Equilibrium (LTE) model using the observed molecular spectra to determine the physical environment in which these molecules originate. We map both the observed spatial distribution and the physical parameters found from the LTE model. We also determine the formation routes of these molecules in each source using the three-phase NAUTILUS chemical evolution code. We detect several lines of propyne, CH$_3$CCH, and cyclopropenylidene, $c$-C$_3$H$_2$ as tracers of carbon chain chemistry, as well as several lines of formaldehyde, H$_2$CO, and methanol, CH$_3$OH, as a precursor and a tracer of complex organic molecule chemistry, respectively. We find excitation temperatures of 20-30 K for the carbon chains and 8-85 K for the complex organics. The CH$_3$CCH abundances are reproduced by a warm-up model, consistent with warm carbon chain chemistry, while the observed CH$_3$OH abundances require a shock mechanism sputtering the molecules into the gas phase.

The K2-138 system hosts six planets and presents an interesting case study due to its distinctive dynamical structure. Its five inner planets are near a chain of 3/2 two-body mean-motion resonances, while the outermost body (planet {\it g}) is significantly detached, having a mean-motion ratio of $n_f/n_g \sim 3.3$ with its closest neighbor. We show that the orbit of $m_g$ is actually consistent with the first-order three-planet resonance (3P-MMR) characterized by the relation $2n_e - 4n_f + 3n_g = 0$ and is the first time a pure first-order 3P-MMR is found in a multi-planet system and tied to its current dynamical structure. Adequate values for the masses allow to trace the dynamical history of the system from an initial capture in a 6-planet chain (with $n_f/n_g$ in a 3/1 resonance), up to its current configuration due to tidal interactions over the age of the star. The increase in resonance offset with semi-major axis, as well as its large value for $n_f/n_g$ can be explained by the slopes of the pure three-planet resonances in the mean-motion ratio plane. The triplets slide outward over these curves when the innermost pair is pulled apart by tidal effects, in a \textit{pantograph-}like manner. The capture into the 3P-MMR is found to be surprisingly robust given similar masses for $m_g$ and $m_f$, and it is possible that the same effect may also be found in other compact planetary systems.

The Panoramic Search for Extraterrestrial Intelligence (PANOSETI) experiment is designed to detect pulsed optical signals on nanosecond timescales. PANOSETI is therefore sensitive to Cherenkov radiation generated by extensive air showers, and can be used for gamma-ray astronomy. Each PANOSETI telescope uses a 0.5 m Fresnel lens to focus light onto a 1024 pixel silicon photomultiplier camera that images a 9.9$^\circ\times$9.9$^\circ$ square field of view. Recent detections of PeV gamma-rays from extended sources in the Galactic Plane motivate constructing an array with effective area and angular resolution surpassing current observatories. The PANOSETI telescopes are much smaller and far more affordable than traditional imaging atmospheric Cherenkov telescopes (IACT), making them ideal instruments to construct such an array. We present the results of coincident observations between two PANOSETI telescopes and the gamma-ray observatory VERITAS, along with simulations characterizing the performance of a PANOSETI IACT array.

We present results from angular cross-correlations between select samples of CHIME/FRB repeaters and galaxies in three photometric galaxy surveys, which have shown correlations with the first CHIME/FRB catalog containing repeating and nonrepeating sources: WISE$\times$SCOS, DESI-BGS, and DESI-LRG. We find a statistically significant correlation ($p$-value $<0.001$, after accounting for look-elsewhere factors) between a sample of repeaters with extragalactic DM $>395$ pc cm$^{-3}$ and WISE$\times$SCOS galaxies with redshift $z>0.275$. We demonstrate that the correlation arises surprisingly because of a statistical association between FRB 20200320A (extragalactic DM $\approx550$ pc cm$^{-3}$) and a galaxy group in the same dark matter halo at redshift $z\approx0.32$. Based on our results, we suggest incorporating galaxy group and cluster catalogs into direct host association pipelines for FRBs with $\lesssim1'$ localization precision, effectively utilizing the two-point information to constrain FRB properties such as their redshift. In addition, we find marginal evidence for a negative correlation at 99.4% CL between a sample of repeating FRBs with baseband data (median extragalactic DM $=354$ pc cm$^{-3}$) and DESI-LRG galaxies with redshift $0.3\le z<0.45$, suggesting that the repeaters might be more prone than apparent nonrepeaters to propagation effects due to intervening free electrons over angular scales $\sim0\mbox{$.\!\!^\circ$}5$.

The face-on projected density profile of the Miyamoto & Nagai disks of arbitrary flattening is obtained analytically in terms of incomplete elliptic integrals of first and second type, by using two complementary approaches, and then checked against the results of numerical integration. As computer algebra systems do not seem able to obtain the resulting formula in any straightforward way, the relevant mathematical steps are provided. During this study, three wrong identities in the Byrd & Friedman tables of elliptic integrals have been identified, and their correct expression is given.

Studying the long-term radio variability (timescales of months to years) of blazars enables us to gain a better understanding of the physical structure of these objects on sub-parsec scales, and the physics of super massive black holes. In this study, we focus on the radio variability of 1157 blazars observed at 15~GHz through the Owens Valley Radio Observatory (OVRO) Blazar Monitoring Program. We investigate the dependence of the variability amplitudes and timescales, characterized based on model fitting to the structure functions, on the milliarcsecond core sizes measured by Very Long Baseline Interferometry. We find that the most compact sources at milliarcsecond scales exhibit larger variability amplitudes and shorter variability timescales than more extended sources. Additionally, for sources with measured redshifts and Doppler boosting factors, the correlation between linear core sizes against variability amplitudes and intrinsic timescales are also significant. The observed relationship between variability timescales and core sizes is expected, based on light travel-time arguments. This variability vs core size relation extends beyond the core sizes measured at 15\,GHz; we see significant correlation between the 15\,GHz variability amplitudes (as well as timescales) and core sizes measured at other frequencies, which can be attributed to a frequency-source size relationship arising from the intrinsic jet structure. At low frequencies of 1\,GHz where the core sizes are dominated by interstellar scattering, we find that the variability amplitudes have significant correlation with the 1~GHz intrinsic core angular sizes, once the scatter broadening effects are deconvoluted from the intrinsic core sizes.

We present a physical model and spin-state analysis of the potentially hazardous asteroid (23187) 2000 PN9. As part of a long-term campaign to make direct detections of the YORP effect, we collected optical lightcurves of the asteroid between 2006 and 2020. These observations were combined with planetary radar data to develop a detailed shape model which was used to search for YORP acceleration. We report that 2000 PN9 is a relatively large top-shaped body with a sidereal rotation period of 2.53216$\pm$0.00015 h. Although we find no evidence for rotational acceleration, YORP torques smaller than $\sim$10$^{-8}$$\,\rm rad/day^{2}$ cannot be ruled out. It is likely that 2000 PN9 is a YORP-evolved object, and may be an example of YORP equilibrium or self limitation.

The next generation of space-based observatories will characterize the atmospheres of low-mass, temperate exoplanets with the direct-imaging technique. This will be a major step forward in our understanding of exoplanet diversity and the prevalence of potentially habitable conditions beyond the Earth. We compute a list of currently known exoplanets detectable with the mid-infrared Large Interferometer For Exoplanets (LIFE) in thermal emission. We also compute the list of known exoplanets accessible to a notional design of the Habitable Worlds Observatory (HWO), observing in reflected starlight. With a pre-existing method, we processed the NASA Exoplanet Archive and computed orbital realizations for each known exoplanet. We derived their mass, radius, equilibrium temperature, and planet-star angular separation. We used the LIFEsim simulator to compute the integration time ($t_{int}$) required to detect each planet with LIFE. A planet is considered detectable if a broadband signal-to-noise ratio $S/N$=7 is achieved over the spectral range $4-18.5\mu$m in $t_{int}\leq$100 hours. We tested whether the planet is accessible to HWO in reflected starlight based on its notional inner and outer working angles, and minimum planet-to-star contrast. LIFE's reference configuration (four 2-m telescopes with 5% throughput and a nulling baseline between 10-100 m) can detect 212 known planets within 20 pc. Of these, 55 are also accessible to HWO in reflected starlight, offering a unique opportunity for synergies in atmospheric characterization. LIFE can also detect 32 known transiting exoplanets. Furthermore, 38 LIFE-detectable planets orbit in the habitable zone, of which 13 with $M_p<5M_\oplus$ and 8 with $5M_\oplus<M_p<10M_\oplus$. LIFE already has enough targets to perform ground-breaking analyses of low-mass, habitable-zone exoplanets, a fraction of which will also be accessible to other instruments.

Aims: We introduce a new deep learning approach for the reconstruction of 3D dust density and temperature distributions from multi-wavelength dust emission observations on the scale of individual star-forming cloud cores (<0.2 pc). Methods: We construct a training data set by processing cloud cores from the Cloud Factory simulations with the POLARIS radiative transfer code to produce synthetic dust emission observations at 23 wavelengths between 12 and 1300 $\mu$m. We simplify the task by reconstructing the cloud structure along individual lines of sight and train a conditional invertible neural network (cINN) for this purpose. The cINN belongs to the group of normalising flow methods and is able to predict full posterior distributions for the target dust properties. We test different cINN setups, ranging from a scenario that includes all 23 wavelengths down to a more realistically limited case with observations at only seven wavelengths. We evaluate the predictive performance of these models on synthetic test data. Results: We report an excellent reconstruction performance for the 23-wavelengths cINN model, achieving median absolute relative errors of about 1.8% in $\log(n_{dust}/m^{-3})$ and 1% in $\log(T_{dust}/K)$, respectively. We identify trends towards overestimation at the low end of the density range and towards underestimation at the high end of both density and temperature, which may be related to a bias in the training data. Limiting coverage to a combination of only seven wavelengths, we still find a satisfactory performance with average absolute relative errors of about 3.3% and 2.5% in $\log(n_{dust}/m^{-3})$ and $\log(T_{dust}/K)$. Conclusions: This proof of concept study shows that the cINN-based approach for 3D reconstruction of dust density and temperature is very promising and even feasible under realistic observational constraints.

The radioactive isotopes of 44Ti and 56Ni are important products of explosive nucleosynthesis, which play a key role for supernova (SN) diagnostics and were detected in several nearby young SN remnants. However, most SN models based on non-rotating single stars predict yields of 44Ti that are much lower than the values inferred from observations. We present, for the first time, the nucleosynthesis yields from a self-consistent three-dimensional (3D) SN simulation of an approximately 19 Msun progenitor star that reaches an explosion energy comparable to that of SN 1987A and that covers the evolution of the neutrino-driven explosion until more than 7 seconds after core bounce. We find a significant enhancement of the Ti/Fe yield compared to recent spherically symmetric (1D) models and demonstrate that the long-time evolution is crucial to understand the efficient production of 44Ti due to the non-monotonic temperature and density histories of ejected mass elements. Additionally, we identify characteristic signatures of the nucleosynthesis in proton-rich ejecta, in particular high yields of 45Sc and 64Zn.

The presence of evolved stars in high-redshift galaxies can place valuable indirect constraints on the onset of star formation in the Universe. Thus we use a combination of PEARLS GTO and public NIRCam photometric data to search for Balmer break candidate galaxies at $7 < z < 12$. We find that our Balmer break candidates at $z \sim 10.5$ tend to be older (115 Myr), have lower inferred [O III] + H$\beta$ emission line equivalent widths (120 \r{A}), have lower specific star formation rates (6 Gyr$^{-1}$) and redder UV slopes ($\beta = -1.8$) than our control sample of galaxies. However, these trends all become less strong at $z \sim 8$, where the F444W filter now probes the strong rest-frame optical emission lines, thus providing additional constraints on the current star formation activity of these galaxies. These weaker trends likely reflect the bursty nature of these Epoch of Reionisation galaxies, which can lead to a disconnect between their current star formation activity and SED profiles, and their more extended star formation history. We discuss how strong emission lines, the cumulative effect of weak emission lines, dusty continua and AGN can all contribute to the photometric excess seen in the rest-frame optical, thus mimicking the signature of a Balmer break. Additional medium-band imaging will thus be essential to more robustly identify Balmer break galaxies. However, the Balmer break alone cannot serve as a definitive proxy for the stellar age of galaxies, being complexly dependent on the star formation history. Ultimately, deep NIRSpec continuum spectroscopy and MIRI imaging will provide the strongest indirect constraints on the formation era of the first galaxies in the Universe, thereby revealing when cosmic dawn breaks.

Based on observations obtained with the Nordic Optical Telescope we investigate the spectral variability of the Herbig Ae star RR Tau. This star belongs to the UX Ori family, characterized by very deep fadings caused by the screening of the star with opaque fragments (clouds) of the protoplanetary discs. At the moments of such minima one observes strong spectral variability due to the fact that the dust cloud occults, for an observer, not only the star but also a part of the region where the emission spectrum originates. We calculated a series of obscuration models to interpret the observed variability of the H-alpha line parameters. We consider two main obscuration scenarios: (1) the dust screen rises vertically above the circumstellar disc, and (2) the screen intersects the line-of-sight moving azimuthally with the disc. In both cases the model of the emission region consists of a compact magnetosphere and a magneto-centrifugal disc wind. Comparison with observations shows that the first scenario explains well the variability of the radiation flux, the equivalent width, as well as the asymmetry of the H-alpha line during eclipses, while the second scenario explains them only partly. This permits us to suggest that in the case of RR Tau, the main causes of the eclipses are either a structured disc wind, or the charged dust lifted along the field lines of the poloidal component of the magnetic field of the circumstellar disc.

Many physically inspired general relativity (GR) modifications predict significant deviations in the properties of spacetime surrounding massive neutron stars. Among these modifications is $f(\mathcal{R}, \mathbb{T})$, where $\mathcal{R}$ is the Ricci scalar, $\mathbb{T}$ represents the trace of the energy-momentum tensor, the gravitational theory that is thought to be a neutral extension of GR. Neutron stars with masses above 1.8 $M_\odot$ expressed as radio pulsars are precious tests of fundamental physics in extreme conditions unique in the observable universe and unavailable to terrestrial experiments. We obtained an exact analytical solution for spherically symmetric anisotropic perfect-fluid objects in equilibrium hydrostatic using the frame of the form of $f(\mathcal{R},\mathbb{T})=\mathcal{R}+\beta \mathbb{T}$ where $\beta$ is a dimensional parameter. We show that the dimensional parameter $\beta$ and the compactness, $C=\frac{ 2GM}{Rc^2}$ can be used to express all physical quantities within the star. We fix the dimensional parameter $\beta$ to be at most. (Here ${\mathrm \kappa^2}$ is the coupling constant of Einstein which is figured as $\kappa^2=\frac{8\pi G}{c^4}$, the Newtonian constant of gravitation is denoted as $G$ while $c$ represents the speed of light.) $\beta_1=\frac{\beta}{\kappa^2}= 0.1$ in positive values through the use of observational data from NICER and X-ray Multi-Mirror telescopes on the pulsar PSR J0740+6620, which provide information on its mass and radius.

Dark photons can oscillate into Standard Model (SM) photons via kinetic mixing. The conversion probability depends sensitively on properties of the ambient background, such as the density and electromagnetic field strength, which cause the SM photon to acquire an in-medium effective mass. Resonances can enhance the conversion probability when there is a level-crossing between the dark photon and background-dependent SM photon states. In this work, we show that the widely used Landau-Zener (LZ) approximation breaks down when there are multiple level-crossings due to a non-monotonic SM photon potential. Phase interference effects, especially when the dark photon mass is close to an extremum of the SM photon effective mass, can cause deviations from the LZ approximation at the level of a few orders of magnitude in the conversion probability. We present an analytic approximation that is valid in this regime and that can accurately predict the conversion probabilities in a wide range of astrophysical environments.

Unmodelled searches and reconstruction is a critical aspect of gravitational wave data analysis, requiring sophisticated software tools for robust data analysis. This paper introduces PycWB, a user-friendly and modular Python-based framework developed to enhance such analyses based on the widely used unmodelled search and reconstruction algorithm Coherent Wave Burst (cWB). The main features include a transition from C++ scripts to YAML format for user-defined parameters, improved modularity, and a shift from complex class-encapsulated algorithms to compartmentalized modules. The pycWB architecture facilitates efficient dependency management, better error-checking, and the use of parallel computation for performance enhancement. Moreover, the use of Python harnesses its rich library of packages, facilitating post-production analysis and visualization. The PycWB framework is designed to improve the user experience and accelerate the development of unmodelled gravitational wave analysis.

Observable properties of neutron stars are studied within a hadronic equation of state derived from the quark level. The effect of short-range repulsion is incorporated within the excluded volume framework. It is found that one can sustain neutron stars with masses as large as 2.2$M_\odot$ even including hyperons in $\beta$ equilibrium, while producing radii and tidal deformabilities consistent with current constraints.

Spin-induced quadrupole moments provide an important characterization of compact objects, such as black holes, neutron stars and black hole mimickers inspired by additional fields and/or modified theories of gravity. Black holes in general relativity have a specific spin-induced quadrupole moment, with other objects potentially having differing values. Different values of this quadrupole moment lead to modifications of the spin precession dynamics, and consequently modifications to the inspiral waveform. Based on the spin-dynamics and the associated precessing waveform developed in our previous work, we assess the prospects of measuring spin-induced moments in various black hole, neutron star, and black-hole mimicker binaries. We focus on binaries in which at least one of the objects is in the mass-gap (similar to the $2.6 M_\odot$ object found in GW190814). We find that for generic precessing binaries, the effect of the spin-induced quadrupole moments on the precession is sensitive to the nature of the mass-gap object, i.e., whether it is a light black hole or a massive neutron star. So that this is a good probe of the nature of these objects. For precessing black-hole mimicker binaries, this waveform also provides significantly tighter constraints on their spin-induced quadrupole moments than the previous results obtained without incorporating the precession effects of spin-induced quadrupole moments. We apply the waveform to sample events in GWTC catalogs to obtain better constraints on the spin-induced quadrupole moments, and discuss the measurement prospects for events in the O$4$ run of the LIGO-Virgo-KAGRA collaboration.

In this paper, I study the location and symmetry of superconducting protons. Solving the Tolman-Oppenheimer-Volkoff (TOV) equations based on the unified Barcelona-Catania-Paris-Madrid equation of state (BCPM EoS) and on the pairing gap calculations by Lim and Holt [1], I find that roughly 500 meters of the liquid core (with isotropic and continuous symmetry) and roughly 100-150 meters of the core-crust interface (with anisotropic symmetry) are superconducting, while the rest of the star is normal. To specify whether the superconducting symmetry is discreet in the pasta phase, I study the coexistence of the saturated nuclear and the pure neutron matter using EoS based on the chiral effective field theory (ChEFT). I find that the maximum pressure at coexistence is $P_{*}\simeq0.5\;{\rm MeV\,fm^{-3}}$. To verify the precision of the coexistence calculations I evaluate the surface and the Coulomb corrections using the compressible liquid drop model. I calculate the proton tunneling rate in the perfectly ordered slab region of the pasta phase and conclude that for the chosen EoS, the proton supercurrent tunneling between the adjacent slabs is negligible and the slab region should be described as a discreet symmetry system of quasi two-dimensional layers.

The hydrogen atoms penetrate the heliosphere from the local interstellar medium, and while being ionized, they form the population of pickup protons. The distribution of pickup protons is modified by the adiabatic heating (cooling) induced by the solar wind plasma compression (expansion). In this study, we emphasize the importance of the adiabatic energy change in the inner heliosheath that is usually either neglected or considered improperly. The effect of this process on the energy and spatial distributions of pickup protons and energetic neutral atoms (ENAs), which originate in the charge exchange of pickup protons, has been investigated and quantified using a kinetic model. The model employs the global distributions of plasma and hydrogen atoms in the heliosphere from the simulations of a kinetic-magnetohydrodynamic model of solar wind interaction with the local interstellar medium. The findings indicate that the adiabatic energy change is responsible for the broadening of the pickup proton velocity distribution and the significant enhancement of ENA fluxes (up to $\sim$5 and $\sim$20 times in the upwind and downwind directions at energies $\sim$1-2 keV for an observer at 1 au). It sheds light on the role of adiabatic energy change in explaining the discrepancies between the ENA flux observations and the results of numerical simulations.

From a theoretical perspective, matter accretion processes around compact objects are highly relevant as they serve as a natural laboratory to test general relativity in the strong field regime. This enables us to validate fundamental concepts such as the no-hair theorem, the cosmic censorship hypothesis, and the existence of alternative solutions to Einstein's equations that mimic the effects of black holes. In this study, we analyze the emission spectra of geometrically thick accretion disks, referred to as Polish doughnuts, around naked singularities described by the $q$-metric. To begin, we revisit the construction of equilibrium configurations of magnetized tori in this spacetime and evaluate the role of the deformation parameter over these configurations. Once we have systematically studied the disks in this spacetime, we use the \texttt{OSIRIS} code to perform a backward ray-tracing method, resulting in the first simulations of the intensity map and emission profiles of magnetized tori within this metric. Furthermore, we validate the effect of both the quadrupole moment and the angular momentum on observable quantities such as flux and intensity for optically thin and thick disks, since for values of $ q < 0$, which correspond to objects with prolate deformation, and which in turn, are constructed with higher values of angular momentum, the emission spectrum exhibits higher intensity than that obtained for Schwarzschild's spacetime. Hence, we find a first differential feature that distinguishes tori formed around naked singularities from those around static black holes.

The decrease of both the rolling speed of the inflaton and the sound speed of the curvature perturbations can amplify the curvature perturbations during inflation so as to generate a sizable amount of primordial black holes. In the ultraslow-roll inflation scenario, it has been found that the power spectrum of curvature perturbations has a $k^4$ growth. In this paper, we find that when the speed of sound decreases suddenly, the curvature perturbations becomes scale dependent in the infrared limit and the power spectrum of the curvature perturbation only has a $k^2$ growth. Furthermore, by studying the evolution of the power spectrum in the inflation model, in which both the sound speed of the curvature perturbations and the rolling speed of the inflaton are reduced, we find that the power spectrum is nearly scale invariant at the large scales to satisfy the constraint from the cosmic microwave background radiation observations, and at the same time can be enhanced at the small scales to result in an abundant formation of primordial black holes. In the cases of the simultaneous changes of the sound speed and the slow-roll parameter $\eta$ and the change of the sound speed preceding that of the slow-roll parameter $\eta$, the power spectrum can possess a $k^6$ growth under certain conditions, which is the steepest growth of the power spectrum reported so far.