Papers for Friday, Jun 06 2025

Differential measurement of the fundamental physical constant mu = m_e/m_p (the electron-to-proton mass ratio) toward two sources located near the Galactic center - the Sagittarius (Sgr) B2(N) and (M) molecular clouds - show a lower mu compared to its terrestrial value. Based on methanol (CH3OH) emission lines from the frequency range 80-112 GHz (IRAM 30-m telescope archival data), the calculated difference (Delta mu)/mu = (mu_obs - mu_lab)/mu_lab is equal to (-3.0 +/- 0.6)*10^(-7) (1 sigma C.L.) in the whole cloud SgrB2. The revealed 5 sigma signal in mu-variations agrees within the margin of error with the recently obtained result based on methanol emission lines from the higher frequency range 542-543 GHz (Herschel space telescope archival data) for SgrB2(N): (Delta mu)/mu = (-4.2 +/- 0.7)*10^(-7).

Type Ia supernovae (SNe Ia) are standardisable candles: their peak magnitudes can be corrected for correlations between light curve properties and their luminosities to precisely estimate distances. Understanding SN Ia standardisation across wavelength improves methods for correcting SN Ia magnitudes. Using 150 SNe Ia from the Foundation Supernova Survey and Young Supernova Experiment, we present the first study focusing on SN Ia standardisation properties in the z band. Straddling the optical and near-infrared, SN Ia light in the z band is less sensitive to dust extinction and can be collected alongside the optical on CCDs. Pre-standardisation, SNe Ia exhibit less residual scatter in z-band peak magnitudes than in the g and r bands. SNe Ia peak z-band magnitudes still exhibit a significant dependence on light-curve shape. Post-standardisation, the z-band Hubble diagram has a total scatter of RMS = 0.195 mag. We infer a z-band mass step of $\gamma_{z} = -0.105 \pm 0.031$ mag, which is consistent within 1$\sigma$ of that estimated from gri data, assuming Rv = 2.61. When assuming different Rv values for high and low mass host galaxies, the z-band and optical mass steps remain consistent within 1$\sigma$. Based on current statistical precision, these results suggest dust reddening cannot fully explain the mass step. SNe Ia in the z band exhibit complementary standardisability properties to the optical that can improve distance estimates. Understanding these properties is important for the upcoming Vera Rubin Observatory and Nancy G. Roman Space Telescope, which will probe the rest-frame z band to redshifts 0.1 and 1.8.

We present spatially-resolved stellar kinematics of 15 massive ($M_*=10^{10.5-11.5}M_{\odot}$) quiescent galaxies at $z\sim1.2-2.3$ from the JWST-SUSPENSE program. This is the largest sample of spatially-resolved kinematic measurements of quiescent galaxies at cosmic noon to date. Our measurements are derived from ultra-deep NIRSpec/MSA stellar absorption line spectra, using a forward modelling approach that accounts for optics, source morphology, positioning, and data reduction effects. 10 out of 15 galaxies are orientated such that we can measure rotational support. Remarkably, all 10 galaxies show significant rotation ($V_{r_e}=117-345$km/s, $\sigma_0 = 180-387$km/s), and are classified as "fast rotators" from their spin parameter. The remaining galaxies are too misaligned with respect to the slit to constrain their rotational velocities. The widespread rotational support in our sample indicates that the process responsible for quenching star formation in early massive galaxies did not destroy rotating disc structures. When combined with other quiescent galaxy samples at $z\sim0.5-2.5$, we find a trend between rotational support and age, with younger quiescent galaxies being more rotationally supported. This age trend has also been found at $z\sim0$, and likely explains why our high-redshift galaxies show more rotational support compared to massive ETGs at $z\sim0$, which are, on average, older. Our kinematic modelling also enables us to calculate dynamical masses. These dynamical masses greatly exceed the stellar masses for our sample (median $M_{\text{dyn}}/M_*=2.7$); they even allow for the bottom-heavy IMF found in the cores of low-$z$ massive ellipticals. Altogether, our results support a scenario in which distant quiescent galaxies evolve into nearby massive ETGs, gradually building up their outskirts and simultaneously losing rotation, due to a series of (mostly minor) mergers.

In early 2024, ESA formally adopted the Laser Interferometer Space Antenna (LISA) space mission with the aim of measuring gravitational waves emitted in the millihertz range. The constellation employs three spacecraft that exchange laser beams to form interferometric measurements over a distance of 2.5 million kilometers. The measurements will then be telemetered down to Earth at a lower sampling frequency. Anti-aliasing filters will be used on board to limit spectral folding of out-of-band laser noise. The dominant noise in these measurements is laser frequency noise which does not cancel naturally in LISA's unequal-arm heterodyne interferometers. Suppression of this noise requires time-shifting of the data using delay operators to build virtual beam paths that simulate equal-arm interferometers. The non-commutativity of these delay operators and on-board filters manifests as a noise (flexing-filtering) that significantly contributes to the noise budget. This non-commutativity is a consequence of the non-flatness of the filter in-band. Attenuation of this noise requires high-order and computationally expensive filters, putting additional demands on the spacecraft. The following work studies an alternative method to reduce this flexing filtering noise via the introduction of a modified delay operator that accounts for the non-commutativity with the filter in the delay operation itself. Our approach allows us to reduce the flexing-filtering noise by over six orders of magnitude whilst reducing the dependency on the flatness of the filter. The work is supplemented by numerical simulations of the data processing chain that compare the results with those of the standard approach.

The upcoming Nancy Grace Roman Space Telescope is set to conduct a generation-defining SN Ia cosmology measurement with its High Latitude Time Domain Survey (HLTDS). However, between optical elements, exposure times, cadences, and survey areas, there are many survey parameters to consider. This work was part of a Roman Project Infrastructure Team effort to help the Core Community Survey (CCS) Committee finalize the HLTDS recommendation to the Roman Observations Time Allocation Committee. We simulate 1,000 surveys, with and without a conservative (volume-limited) version of the Vera C. Rubin Observatory Deep Drilling Field SNe Ia, and compute Fisher-matrix-analysis Dark Energy Task Force Figures of Merit (FoM, based on w0-wa constraints) for each. We investigate which survey parameters correlate with FoM, as well as the dependence of the FoM values on calibration uncertainties and the SN dispersion model. The exact optimum depends on the assumed dispersion model and whether Rubin DDF SNe Ia are also considered, but ~20% time in prism, ~30--40% time in Wide imaging and the remainder in Deep imaging seems most promising. We also advocate for "interlaced" cadences where not every filter is used in every cadence step to reduce overheads while maintaining a good cadence and increasing the number of filters compared to the Rose et al. (2021) reference survey (the prism has proportionately lower overheads and can be used for each cadence step). We show simulated light curves and spectra for the baseline HLTDS CCS recommendation and release distance-modulus covariance matrices for all surveys to the community.

We present a new method to calculate bolometric luminosities for unobscured, type 1 quasars with multi-band photometric data. Bolometric luminosity is a fundamental property to understand quasars and it is commonly estimated from monochromatic luminosities using bolometric corrections that often neglect quasar SED diversity. We take advantage of the fact that most quasars now have multi-band observations from UV to mid-IR, and construct SEDs for a well-defined sample of SDSS quasars at $0.5\leq z\leq 2$. Based on this fiducial sample, we explore quasar SEDs, their diversity, and their relations with bolometric luminosities. We then use unsupervised neural network self-organizing maps (SOM) to describe the SED diversity and compute the bolometric luminosities with a fully-trained SOM model. This method reduces systematical uncertainties compared to the traditional method. In addition, we update the multi-linear regression relations between bolometric luminosity and monochromatic luminosities at restframe 1450Å, 3000Å, and 5100Å. Our method is applicable to large quasar samples with a wide range of luminosity and redshift. We have applied it to the SDSS DR16 quasars. We have also made our code publicly available.

Observations and high-resolution hydrodynamical simulations indicate that massive star clusters form through a complex hierarchical assembly. We use simulations including post-Newtonian dynamics and stellar evolution to investigate this collisional assembly with the \bifrost{} code coupled to the \sevn{} stellar evolution module. With a full initial stellar mass function, we study the effect of initial binary and triple stars as well a high initial single star mass limit (450 $M_\odot$) on the hierarchical assembly, structure, and kinematics of massive ($M_\mathrm {cl}\sim10^6 M_\odot$, $N=1.8 \times 10^6$) star clusters. Simultaneously, intermediate mass black holes (IMBHs), potential seeds for supermassive black holes, can form and grow in our models by stellar collisions, tidal disruption events (TDEs) and black hole (BH) mergers. At a fixed cluster mass, stellar multiplicity or a high mass limit increase the numbers (up to $\sim$ 10) and masses (up to $10^4 M_\odot$) of the formed IMBHs within the first 10 Myr of cluster evolution. The TDE rates peak at $\Gamma_\mathrm {tde}\sim 5 \times 10^{-5}$ yr$^{-1}$ shortly after IMBH formation at $\sim 2$ Myr. In all simulations, we find gravitational wave driven mergers involving stellar BHs and IMBHs. Initial multiplicity or a high mass limit also result in IMBH-IMBH mergers. The IMBH masses correlate with the initial cluster masses, surface densities and velocity dispersions approximately as $M_\bullet \propto M_\mathrm{cl}$, $M_\bullet \propto \Sigma_\mathrm{h}^\mathrm{3/2}$ and $M_\bullet \propto \sigma^\mathrm{3}$. Our results suggest IMBH masses above $M_\bullet \gtrsim 10^4 M_\odot$ for the dense $z\sim10$ star clusters recently observed by the James Webb Space Telescope.

NASA's Nancy Grace Roman Space Telescope (Roman) will provide an opportunity to study dark energy with unprecedented precision and accuracy using several techniques, including measurements of high-$z$ Type Ia Supernovae (SNe Ia, $z \lesssim 3.0$) via the High-Latitude Time Domain Survey (HLTDS). In this work, we do an initial "benchmark" characterization of the photometric repeatability of stellar fluxes, which must be below $1\%$ when sky noise is subdominant in order xto enable a number of calibration requirements. Achieving this level of flux precision requires attention to Roman's highly-structured, spatially-varying, undersampled PSF. In this work, we build a library of effective PSFs (ePSFs) compatible with the OpenUniverse HLTDS simulations. Using our library of ePSFs, we recover fractional flux between $0.6 - 1.2\%$ photometric precision, finding that redder bands perform better by this metric. We also find that flux recovery is improved by up to $20\%$ when a chip (sensor chip assembly; SCA) is divided into 8 sub-SCAs in order to account for the spatial variation of the PSF. With our optimized algorithm, we measure non-linearity due to photometry (magnitude dependence) of $|s_{NL}| < 1.93 \times 10^{-3}$ per dex, which is still larger than stated requirements for detector effects and indicates that further work is necessary. We also measure the dependence of photometric residuals on stellar color, and find the largest possible dependence in R062, implying a color-dependent PSF model may be needed. Finally, we characterize the detection efficiency function of each OpenUniverse Roman filter, which will inform future studies.

We present a minimally model-dependent framework for testing late-time cosmological models using Uncalibrated Cosmic Standards (UCS), including standard rulers and standard candles, without relying on absolute calibrations. The method exploits a tight, model-insensitive correlation between the sound horizons at recombination and the drag epoch. By avoiding dependence on pre-recombination physics and the amplitude of the Cosmic Microwave Background (CMB) power spectra, the UCS framework reduces potential early-time biases while retaining much of the constraining power of full analyses. Applying UCS to the recent dynamical dark energy (DE) study that reported deviations from $\Lambda$CDM, we find the constraints shift systematically toward the $\Lambda$CDM case, suggesting the present of pre-recombination physics or systematics that likely affect the scale-dependence of the CMB spectra. We also observe a mild tension between uncalibrated standard rulers and candles, which can be largely mitigated by introducing a redshift-dependent magnitude bias in the supernova (SNe Ia) data. Our results highlights the importance of isolating post-recombination observables for testing late-time models in the era of precision cosmology, positioning UCS analysis as a robust framework for upcoming galaxy surveys.

We discuss a modification of a recently developed numerical scheme for evolving spherically symmetric self-gravitating systems to include the effects of self-interacting dark matter. The approach is far more efficient than traditional N-body simulations and cross sections with different dependencies on velocity and scattering-angle are easily accommodated. To demonstrate, we provide results of a simulation, which runs quickly on a personal computer, that shows the expected initial flattening of the inner region of an NFW halo as well as the later gravothermal collapse instability that leads to a dense core at the galactic center. We note that this approach can also be used, with some augmentation, to simulate the dynamics in globular clusters by modeling gravitational hard scattering as a self-interaction.

We present an efficient Bayesian SED-fitting framework tailored to multiwavelength pixel photometry from the JWST Advanced Deep Extragalactic Survey (JADES). Our method employs simulation-based inference to enable rapid posterior sampling across galaxy pixels, leveraging the unprecedented spatial resolution, wavelength coverage, and depth provided by the survey. It is trained on synthetic photometry generated from MILES stellar population models, incorporating both parametric and non-parametric SFHs, realistic noise, and JADES-like filter sensitivity thresholds. We validate this amortised inference approach on mock datasets, achieving robust and well-calibrated posterior distributions, with an $R^2$ score of 0.99 for stellar mass. Applying our pipeline to real observations, we derive spatially resolved maps of stellar population properties down to $\mathrm{S/N}_{\rm{pixel}}=5$ (averaged over F277W, F356W, F444W) for 1083 JADES galaxies and ~2 million pixels with spectroscopic redshifts. These maps enable the identification of dusty or starburst regions and offer insights into mass growth and the structural assembly. We assess the outshining phenomenon by comparing pixel-based and integrated stellar mass estimates, finding limited impact only in low-mass galaxies ($<10^8M_{\odot}$) but systematic differences of ~0.20 dex linked to SFH priors. With an average posterior sampling speed of $10^{-4}$ seconds per pixel and a total inference time of ~1 CPU-day for the full dataset, our model offers a scalable solution for extracting high-fidelity stellar population properties from HST+JWST datasets, opening the way for statistical studies at sub-galactic scales.

We present flux measurements of the coronal lines [Fe VII] and [Fe X] spanning three decades, in the highly variable Active Galactic Nucleus (AGN) MKN 110. These coronal lines are sensitive to the spectral energy distribution (SED) of AGNs in the extreme ultraviolet (EUV). Neither [Fe VII] nor [Fe X] demonstrates variability in the short term on a weekly or monthly timescale. However, by taking advantage of a long term decrease in the continuum flux of MKN 110 on the order of years, we were able to track the [Fe VII] and [Fe X] fluxes as they respond to the continuum. We were able to detect a lag for [Fe VII] relative to the continuum at 5100 Å, with a modal lag of 652 days, but were unable to detect a significant lag in the [Fe x] flux, though there exist significant uncertainties in the [Fe X] fit. These two lag results are not consistent and the line widths for the two line species also do not match. This provides strong evidence for stratification within the coronal line region (CLR). There is also evidence of a non-varying component within the coronal line flux, probably a result of a more extended region of origin. Taken together, these results suggest a CLR where the bulk of the [Fe VII] originates on parsec scales, but a portion of the [Fe VII] flux originates further out, at or beyond a 10 pc scale. These results also indicate the limitations of single-cloud models in describing the physical conditions of the CLR.

A core motivation of science is to evaluate which scientific model best explains observed data. Bayesian model comparison provides a principled statistical approach to comparing scientific models and has found widespread application within cosmology and astrophysics. Calculating the Bayesian evidence is computationally challenging, especially as we continue to explore increasingly more complex models. The Savage-Dickey density ratio (SDDR) provides a method to calculate the Bayes factor (evidence ratio) between two nested models using only posterior samples from the super model. The SDDR requires the calculation of a normalised marginal distribution over the extra parameters of the super model, which has typically been performed using classical density estimators, such as histograms. Classical density estimators, however, can struggle to scale to high-dimensional settings. We introduce a neural SDDR approach using normalizing flows that can scale to settings where the super model contains a large number of extra parameters. We demonstrate the effectiveness of this neural SDDR methodology applied to both toy and realistic cosmological examples. For a field-level inference setting, we show that Bayes factors computed for a Bayesian hierarchical model (BHM) and simulation-based inference (SBI) approach are consistent, providing further validation that SBI extracts as much cosmological information from the field as the BHM approach. The SDDR estimator with normalizing flows is implemented in the open-source harmonic Python package.

The chemical characterization of galaxies in the first billion years after the Big Bang is one of the central goals of current astrophysics. Optical/near-infrared spectroscopy of long gamma-ray bursts (GRBs) have been heralded as an effective diagnostic to probe the interstellar medium of their host galaxies and their metal and dust content, up to the highest redshift. An opportunity to fulfill this expectation was provided by the recent blast triggered by the Neil Gehrels Swift Observatory of GRB 240218A at redshift z=6.782. We study a high-redshift galaxy selected in a complementary way with respect to flux-limited surveys, not depending on galaxy luminosity and stellar mass. We present the VLT/X-shooter spectrum of its afterglow enabling the detection of neutral-hydrogen, low-ionization, high-ionization and fine-structure absorption lines. We determine the metallicity, kinematics and chemical abundance pattern, providing the first detailed characterization of the neutral gas of a galaxy at z>6.5. From the analysis of fine-structure lines we estimate the distance of the closest gas clouds as $d_{II}=620^{+230}_{-140}$ pc. We determine a high neutral hydrogen column density, $\log(N(HI)/cm^{-2})=22.5\pm0.3$, which is the highest one at z>6 determined so far for a GRB host galaxy, as well as a surprisingly high metal column density, $\log(N(ZnII)/cm^{-2})>14.3$. The observed metallicity of the host galaxy system is [Zn/H]>-0.8. We find evidence of a high amount of dust depletion and of aluminum overabundance, although a number of transitions are saturated. The high hydrogen column density, metal abundances and dust depletion in the neutral gas align with those of the ionized gas of very high-redshift galaxies unveiled by ALMA and JWST, testifying that a rapid build up of metals and dust, and massive neutral hydrogen reservoirs seem to be common features of galaxies in the early Universe.

REJ1034+396 is one of the few active galactic nuclei with a significant quasi-periodic oscillation (QPO). The QPO has been observed in over 1 Ms of XMM-Newton observations spanning over a decade. We investigate the power spectral density function (PSD) of 7 long (~90 ks) XMM-Newton observations of the active galactic nucleus REJ1034+396 in two energy bands. The soft (0.3-0.5 keV) band targets emission from the disk, while the hard (2-7 keV) band isolates the primary X-ray continuum emission from the corona. The QPO is significantly detected in the hard band of 5 of the 7 observations. The best fitting models indicate that the QPO detection in both bands is entirely attributable to the coronal emission with no additional contribution from the disk. This explains the strong coherence between the hard and soft bands at the QPO frequency. The covariance spectrum is consistent with this picture as the variability at QPO frequencies is attributed solely to fluctuations in the hot corona. The time lag as a function of energy is well described by a ~2000 s intrinsic soft lag, resulting from the disk responding to emission from the corona, that undergoes phase wrapping at approximately the QPO frequency. By demonstrating that in this system the QPO arises in the corona, we provide new insights into the mechanisms generating QPOs.

The characterization of nearby rocky exoplanets will become feasible with the next generation of telescopes, such as the Extremely Large Telescope (ELT) and the mission concept Habitable Worlds Observatory (HWO). Using an improved model setup, we aim to refine the estimates of reflected and polarized light contrast for a selected sample of rocky exoplanets in the habitable zones of nearby stars. We perform advanced 3D radiative transfer simulations for Earth-like planets orbiting G-type and M-type stars. Our simulations incorporate realistic, wavelength-dependent surface albedo maps and a detailed cloud treatment, including 3D cloud structures and inhomogeneities, to better capture their radiative response. These improvements are based on Earth observations. We present models of increasing complexity, ranging from simple homogeneous representations to a detailed Earth-as-an-exoplanet model. Our results show that averaging homogeneous models fails to capture Earth's full complexity, especially in polarization. Moreover, simplistic cloud models distort the representation of absorption lines at high spectral resolutions, particularly in water bands, potentially biasing atmospheric chemical abundance estimates. Additionally, we provide updated contrast estimates for observing rocky exoplanets around nearby stars with upcoming instruments such as ANDES and PCS at the ELT. Compared to previous studies, our results indicate that reflected light contrast estimates are overestimated by a factor of two when simplified cloud and surface models are used. Instead, measuring the fractional polarization in the continuum and in high-contrast, high-resolution spectra may be more effective for characterizing nearby Earth-like exoplanets. These refined estimates are essential for guiding the design of future ELT instruments and the HWO mission concept.

James Webb Space Telescope (JWST) has revealed a population of red and compact objects with a unique V-shape SED at z >= 4 known as Little Red Dots (LRDs). Most of the LRDs with existing spectral observations exhibit broad Balmer lines and are thus likely to host active galactic nuclei (AGNs). Here we present a study of LRDs with no broad H-alpha component. Our sample consists of five LRDs at z~5 with H-alpha line widths of about 250 km/s. They are selected from 32 LRDs that have NIRSpec high- or medium-resolution grating spectra covering H-alpha. During our construction of the sample, we find that approximately 20 percent of the LRD candidates previously selected do not show red continuum emission but resemble the V-shape spectra due to strong line emission. Compared to normal star-forming galaxies, narrow-line LRDs tend to have relatively higher H-alpha line widths and luminosities. If these LRDs are dominated by galaxies, our SED modeling suggests that they are dusty, compact star-forming galaxies with high stellar masses and star formation rates (SFRs). Alternatively, if their SEDs are produced by AGNs, the inferred central black hole masses (MBH) are in the range of 10^5 to 10^6 solar masses, placing them at the low-mass end of the AGN population. They may represent an early stage of super-Eddington growth, where the black holes have yet to accumulate significant masses. With large measurement uncertainties, these black holes appear slightly overmassive relative to the local MBH-Mstar relation, but consistent or undermassive with respect to the MBH-sigma and MBH-Mdyn relations. We further find that nearly half of the high-redshift broad-line AGNs exhibit V-shape SEDs. (abridged)

Identifying dwarf galaxies within the Local Volume is crucial for constraining the luminosity function of satellite galaxies in the nearby universe. We report the detection capabilities of dwarf galaxies within the Local Volume using the Chinese Space Station Telescope (CSST). Based on the simulated imaging data of CSST, we develop a detection and classification pipeline that combines traditional image-based search techniques with advanced machine learning classification models. The simulated Local Volume dwarf galaxies can be identified using a pre-processing method for "extended source detection", followed by classification with a pretrained ViT-Base model. This pipeline achieves a true positive rate (TPR) exceeding 85% with a false positive rate (FPR) of only 0.1%. We quantify the detection completeness of Local Volume dwarf galaxies across a three-dimensional parameter space defined by absolute magnitude ($M_V$), half-light radius ($R_h$), and heliocentric distance, based on simulated single-exposure CSST wide-field imaging survey data. For unresolved or semi-resolved dwarf galaxies, our method achieves a significantly deeper absolute magnitude detection limit compared to catalog-based approaches, reaching $M_V = -7$ within 10 \Mpc. By combining this image-based approach with traditional stellar catalog-based "matched filter" techniques, our automated framework established in this work can identify dwarf galaxies within 20 \Mpc for the CSST mission.

We present a statistical, observational study of the $1/f$ range of solar wind turbulence, where $f$ denotes frequency, using in situ data from the Parker Solar Probe (PSP). We compute the energy cascade rate using the third order law of incompressible magnetohydrodynamic (MHD) turbulence, incorporating expansion terms to account for solar wind dynamics. Our results reveal a $1/\tau$ dependence of the energy cascade rate, where $\tau$ is the temporal lag, within the $1/f$ range, in contrast to the constant cascade rate in the inertial range. To explain this behavior, we propose a new intermittent model predicting a $1/\ell$ scaling of the cascade rate, where $\ell$ represents the spatial lag. The analysis of the probability density function (PDF) of magnetic field increments confirms the intermittent nature of the parallel fluctuation component, whereas the perpendicular fluctuations are found to be quasi Gaussian. These findings provide new insights into energy transfer processes in the $1/f$ range of solar wind turbulence, with potential applications in planetary magnetosheaths.

Massive black hole binaries (MBHBs) form through galaxy mergers and are among the loudest sources of gravitational waves (GWs) in the universe. If the binary inspiral time is long, a subsequent galaxy merger can introduce a third black hole, forming a triple system. In the Illustris cosmological simulation, 6% of MBHBs form such triples at parsec scales, where strong three-body interactions are likely. We apply results from numerical simulations of triple MBHs to strong triples identified in Illustris to assess their impact on MBH mergers and recoils. We find that strong triple interactions increase the overall merger fraction by 4%. Including triple interactions raises the merger fraction of MBHs in strong triple systems from 40% to 69%, relative to modeling binary evolution in isolation. Furthermore, massive, major mergers are over three times more likely to be facilitated by strong triple interactions than mergers in general. We also compare GW recoil kicks to gravitational slingshot kicks from triple interactions. Both mechanisms can produce kicks exceeding host escape speeds, ejecting MBHs and producing wandering or offset black holes. Although slingshots yield the highest velocity kicks, GW recoils dominate the ejected population when assuming random MBH spin orientations. Under this assumption, ejections from GW recoil and slingshot kicks reduce the total number of mergers by 6%. Our results highlight the impact of strong triple dynamics and GW recoils on MBH evolution and support their inclusion in cosmological simulations.

We analysed high time-resolution optical photometric data from the Transiting Exoplanet Survey Satellite (TESS) to study the timing behaviour of four intermediate polar-like objects, namely, V1460 Her, 1RXS J045707.4+452751, Swift J0958.0-4208, and V842 Cen. In the case of V1460 Her, we refined the measurement of its orbital period. Long-term observations suggest a gradual decrease in the orbital period of V1460 Her, and the stable light curve during the TESS observations indicates its quiescent state. We detected a beat period of 1290.6 $\pm$ 0.5 s for the first time for the source 1RXS J045707.4+452751, suggesting a possible disc-overflow accretion scenario. For the sources Swift J0958.0-4208 and V842 Cen, we determined periods 6.11 $\pm$ 0.02 h and 3.555 $\pm$ 0.005 h, respectively, which can be provisionally suggested to be orbital periods. These findings provide valuable insights into the accretion processes and long-term evolution of these intriguing binary systems.

We propose a novel test of gravity that combines galaxy clustering with gravitational lensing. In general relativity, the evolution of matter density fluctuations and of the Weyl potential -- the sum of spatial and temporal distortions of the geometry -- are governed by the same growth function. In contrast, alternative theories of gravity that modify the relation between geometry and matter content can lead to differences in these two growths. Exploiting a recent method to directly measure the Weyl potential, we construct a null test that deviates from zero if and only if there is a mismatch between the growth rate of density and that of geometry distortions. We show that changes in the background expansion due to alternative dark energy models and additional forces in the dark matter sector induce no deviations in this test, making it a robust probe for detecting departures from general relativity. Applying the test to current data, we find no evidence of deviation. From an initial $z_*=10$ to $z\sim 0.5$, we constrain the evolution of the Weyl potential to track that of the density to within 33\%. Combining stage-IV surveys will improve the precision across a broad redshift range, limiting differences between the two evolutions to below $2-4\%$.

Within the next few years, the upcoming Nancy Grace Roman Space Telescope will be gathering data for the High Latitude Time Domain Survey (HLTDS) that will be used to significantly improve the Type Ia supernova measurement of the dark energy equation of state parameters w0 and wa. Here we generate a catalog-level simulation of the in-guide strategy recommended by the HLTDS definition committee, and determine dark energy parameter constraints using a detailed analysis that includes light curve fitting, photometric redshifts and classification, BEAMS formalism, systematic uncertainties, and cosmology fitting. After analysis and selection requirements, the sample includes 10,000 Roman SNe Ia that we combine with 4,500 events from LSST. The resulting dark energy figure of merit is well above the NASA mission requirement of 326, with the caveat that SN Ia model training systematics have not been included.

We have conducted a time-resolved spectral analysis of magnetar bursts originating from SGR J1550-5418. Our analysis utilizes a two-step methodology for temporal segmentation of the data. We first generated and fitted overlapping time segments. Subsequently, we obtained non-overlapping time segments with varying lengths based on their spectral evolution patterns, employing a machine learning algorithm called k-means clustering. For the fitting process, we employed three distinct models, namely a modified blackbody (MBB-RCS), a double blackbody (BB+BB), and a power law with an exponential cut-off (COMPT) model. We found that nearly all of the time segments fit well with the COMPT model. Both the average peak energy in the ${\nu}$F${\nu}$ spectra (Epeak) and Photon Index parameters follow a Gaussian distribution with the means ${\sim}$30 keV and -0.5, respectively. Furthermore, there is a strong positive correlation between the cooler and hotter temperature parameters of the BB+BB model, and both two parameters show a Gaussian distribution with peaks ${\sim}$4 keV and 12 keV, respectively. Additionally, we found that the distribution of the temperature parameter of the MBB-RCS model can be fitted with a skewed Gaussian function with a peak ${\sim}$9-10 keV. Lastly, we searched for quasiperiodic spectral oscillations (QPSOs) in the hardness ratio evolution of the bursts. We identified five potential QPSO candidates at frequencies ranging from ${\sim}$15 Hz to ${\sim}$68 Hz. We discuss and compare these results with previous studies.

Over the past decade, SPHERE scattered light observations of protoplanetary discs have revealed previously unseen features with unprecedented resolution. One such feature are radial streaks of reduced brightness that are commonly interpreted as shadows. A possible cause for these shadows is an embedded companion within the disc. In this work, we use 3D radiative transfer simulations with RADMC-3D to investigate the shadowing effects of embedded companions across a range of orbital distances (5-30 au) and companion masses (0.5-30 Jupiter masses). We model 0.1 $\mu$m dust grains, which are well-coupled to the gas, to produce synthetic scattered light images of the disc. Companions with masses equal to or greater than 14 Jupiter masses consistently cast detectable shadows throughout the disc. We hence derive an empirical solution to describe the width and depth of the shadow as functions of companion mass and location. This scaling suggests that shadow features observed in scattered light images could serve as reliable indicators of companion mass and position, providing an indirect method for identifying and characterising otherwise challenging-to-detect objects within these discs. Additionally, our analysis reveals that companion shadows influence the disc thermal structure, with notable cooling effects that could impact disc chemistry and the dynamics of planet formation.

The mid-M star TOI~1227 hosts among the youngest known transiting exoplanets. We have conducted new X-ray imaging and optical spectroscopic observations of TOI 1227 aimed at ascertaining its age and the influence of its high-energy radiation on the exoplanet, TOI 1227b. We obtained a definitive X-ray detection of TOI 1227 with Chandra/HRC-I, and measured its Li and H$\alpha$ lines using ANU SSO 2.3 m telescope (WiFeS) spectroscopy. Through spatiokinematic, isochronal, and SED-based modeling, we have constrained the age of TOI 1227 as lying between 5 Myr and 12 Myr, with a best estimate of $\sim$8 Myr. In the context of this age, we model the evolution of the transiting exoplanet TOI 1227b, using the X-ray luminosity derived from Chandra HRC-I imaging. Our modeling suggests that TOI 1227b is currently undergoing rapid atmospheric mass loss at rates on the order of $\sim 10^{12}$ g s$^{-1}$. The modeling demonstrates that the exoplanet's predicted future evolution depends sensitively on assumptions for total and core planet mass, highlighting the importance of follow-up observations of the TOI 1227 star-exoplanet system to enable measurements of both planetary mass and mass-loss rate.

The nature of the obscuring material in active galactic nuclei (AGN) can be studied by measuring changes in the line-of-sight column density, $N_{\rm H,los}$, over time. This can be accomplished by monitoring AGN over long periods of time and at all timescales. However, this can only be done for a few selected objects as it is resource intensive. Therefore, the best option currently is to focus on population statistics based on the available archival data. In this work, we estimate a lower limit on the fraction of sources in the local $(z<0.1)$ universe that display spectral variability among observations ($54\pm11$%), indicative of $N_{\rm H,los}$ variability. Interestingly, we also find that the variable fraction is similar for both Seyfert 1 ($f_{\rm Sy1}\sim61^{+13}_{-15}$%) and Seyfert 2 ($f_{\rm Sy2}\sim47\pm15$%) galaxies, and discuss why we might find a slightly higher $f_{\rm Sy1}$. We also present a sample of 43 Seyfert 1 and Seyfert 2 galaxies with multiple Chandra observations whose properties make them promising $N_{\rm H,los}$-variable targets. We discuss the accuracy of our method, and search for potential dependencies on the timescale between variable and non-variable observation pairs within a given source. In agreement with previous studies, we find evidence that more variability occurs on longer timescales than on shorter timescales.

As thousands of new open clusters in the Galaxy have recently been reported with reddening or extinction information, we map the distribution and properties of the Galaxy's interstellar material in the Galactic disk as traced by these open clusters. By analyzing the distribution of interstellar extinction for 6215 open clusters located at low Galactic latitude b <= 6 deg, corresponding to the thin Galactic disk, we identify a reddening plane characterized by a dust layer whose thickness varies with Galactic longitude. By splitting the open clusters sample into several sub-regions of Galactic longitude, we observe that the reddening plane is not perfectly aligned with the formal Galactic plane, but instead varies sinusoidally around the Galactic mid-plane. The maximum and minimum interstellar absorption occur at approximately 42 deg and 222 deg, respectively, along the Galactic longitude. Our analysis reveals a noticeable north-south asymmetry in the distribution of interstellar absorption, with a higher proportion of interstellar material below the Galactic plane. We also find that the Sun is located 15.7 +/- 7.3 pc above the reddening plane. The scale height of the open clusters from the reddening plane is estimated to be z_h = 87.3 +/- 1.8 pc. The mean thickness of the absorbing material in the reddening plane, which represents the average extent of the dust layer responsible for interstellar extinction, is found to be about 201 +/- 20 pc. Our findings provide insights into the distribution of interstellar dust, its relationship with the Galactic thin disk, and its implications for the Galactic structure.

Context. M stars are preferred targets for studying terrestrial exoplanets, for which we hope to obtain their atmosphere spectra in the next decade. However, M dwarfs have long been known for strong magnetic activity and the ability to frequently produce optical, broadband emission flares. Aims. We aim to characterise the flaring behaviour of young M dwarfs in the temporal, spectral, and energetic dimensions, as well as examine the stellar parameters governing this behaviour, in order to improve our understanding of the energy and frequency of the flare events capable of shaping the exoplanet atmosphere. Methods. Young Moving Group (YMG) members provide a unique age-based perspective on stellar activity. By examining their flare behaviour in conjunction with rotation, mass, and H{\alpha} data, we obtain a comprehensive understanding of flare activity drivers in young stars. Results. We demonstrate that young stars sharing similar stellar parameters can exhibit a variety in flare frequency distributions and that the flare behaviour shows indications of difference between optical and far-UV. We propose that the period of rotation, not the age of the star, can be a good proxy for assessing flaring activity. Furthermore, we recommend that instead of a simple power law for describing the flare frequency distribution, a piecewise power law be used to describe mid-size and large flare distributions in young and active M dwarfs. Conclusions. Using known periods of rotation and fine-tuned power laws governing the flare frequency, we can produce a realistic sequence of flare events to study whether the atmosphere of small exoplanets orbiting M dwarf shall withstand such activity until life can emerge.

We present a wide-ranging but in-depth analysis of Centaurs, focusing on their physical and structural aspects. Centaurs, originating from the Scattered Disk and Kuiper Belt, play a crucial role in our understanding of Solar System evolution. We first examine how biases in discovery and measurement affect our understanding of the Centaur size distribution. In particular we address the strong dependence of the census on perihelion distance and the broad distribution of Centaur geometric albedos. We explore the rotational characteristics derived from lightcurves, revealing a diverse range of spin rates and photometric variabilities, with most Centaurs showing low amplitude lightcurves, suggesting near-spherical shapes. Additionally, we investigate the relationships between Centaur orbital parameters, surface colors, and physical properties, noting a lack of correlation between rotational dynamics and orbital evolution. We also address the influence of sublimation-driven activity on Centaur spin states, and the rarity of contact binaries. We then discuss some observational and modeling limitations from using common observations (e.g. visible or infrared photometry) to determine diameters and shapes. Following that, we give some points on understanding how Centaur diameters and shapes can reveal the `primitive' nature of the bodies, emphasizing the important role occultation observations play. We also then assess how the Centaur size distribution we see today has been influenced by the collisions in both the primordial Kuiper Belt and in the subsequent Scattered Disk. Finally, we end the chapter with a short narrative of future prospects for overcoming our current limitations in understanding Centaur origins and evolution.

Classical Ae (CAe) stars are main sequence, A-type stars with H{\alpha} emission but no signature of dust. They are thought to be the cool extension of the classical Be stars to lower masses. Recent surveys based on H{\alpha} spectroscopy have significantly increased the number of known CAe stars, with the population extending to spectral types as cool as A4 (Teff approx. 8500 K). We compute the temperature structure of gaseous, circumstellar disks around A-type stars, including both radiative heating from the central star and viscous shear heating from the disk's rotation. We find that shear heating can become important for spectral types A2 and later and can act to increase the low temperatures predicted by purely radiatively heated disks. Our modeling indicates that the presence and strength of H{\alpha} emission for spectral types A2 and later significantly increases with the amount of shear heating included, and we propose that this dependence can be used to constrain the {\alpha} viscosity parameter appropriate for CAe star disks.

Radio wavelengths offer a unique window into high-energy astrophysical phenomena that may be obscured or too rapidly evolving to be captured at other wavelengths. Leveraging data from the Very Large Array Sky Survey, we perform a systematic search for fast, luminous transients with characteristic timescales $\lesssim 3$ years in the nearby universe ($z \leq 0.3$). We report the discovery of five such transients, and classify them based on their synchrotron emission energetics and host galaxy properties. From this sample, we derive observational constraints on the volumetric rates of certain corresponding transient classes. We limit the rates of accretion-induced collapse of white dwarfs with dense circumstellar medium interaction (and those producing pulsar wind nebulae) at $\lesssim 1.10_{-0.90}^{+2.60}$% ($\lesssim 0.20_{-0.10}^{+5.80}$%) of the local Type Ia supernova rate, respectively, broadly consistent with theoretical predictions. For AT2018cow-like radio-bright luminous fast blue optical transients, we estimate a rare occurrence rate of $\lesssim 0.02_{-0.01}^{+0.32}$% of the local core-collapse supernova rate. We constrain the local volumetric rates of long- and short-duration gamma-ray bursts (GRBs) to be $\lesssim 11.46_{-9.48}^{+26.28}$~Gpc$^{-3}$~yr$^{-1}$ and $\lesssim 80.88_{-66.90}^{+185.87}$~Gpc$^{-3}$~yr$^{-1}$, respectively. These estimates incorporate beaming corrections, with median detectable viewing angles derived from afterglow simulations of $\sim 0.4$ and $\sim 0.3$ radians for long- and short-duration GRBs. Our findings highlight the potential of radio surveys to uncover rare, energetic transients. We emphasize the critical role of coordinated multi-wavelength follow-up in fully characterizing these enigmatic events.

The nature of irregularly spaced pulses of rotating radio transients (RRATs) complicates interstellar scintillation studies. In this letter, we report the primary scintillation parameters of a sample of RRATs using pairwise correlations of pulse spectra. Moreover, from the measured scintillation velocities, we constrain their transverse velocities. We also find a reduced modulation index, $\rm{m=0.13\pm0.01}$, for RRAT~J1538+2345. Several possible explanations are discussed. Furthermore, the single-pulse-based interstellar scintillation technique is applicable to other pulsar populations, including nulling pulsars and those with short scintillation timescales, and fast radio bursts.

The Vera C. Rubin Observatory will conduct the Legacy Survey of Space and Time (LSST), delivering deep, multi-band ($ugrizy$) imaging data across 18,000 square degrees over the next decade. Before this ultra-wide-field survey, we constructed a broad-band Ly$\alpha$ imaging toward 483 SDSS/BOSS quasars at $z=$ 1.9-3.0, using deep, wide-field ultraviolet to near-infrared ($u$-to-$K$) data from the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP), the CFHT Large Area U-band Deep Survey (CLAUDS), the Deep UKIRT Near-Infrared Steward Survey (DUNES$^2$), and additional public data covering 13 square degrees. Our broad-band selection allowed us to select 24 candidate quasar nebulae that exhibit $u$ or $g$ band excess over 50-170 kpc, some of which exhibit asymmetrical extended features similar to those seen in previously discovered giant nebulae. We then investigated whether the Ly$\alpha$ morphology of quasar nebulae differs between two redshift intervals, $z=$ 1.9-2.3 and $z=$ 2.3-3.0, and examined environmental dependence based on a control sample. Comparison results show no significant difference in asymmetry within Ly$\alpha$ nebulae between the two redshift intervals. Furthermore, we found no systematic differences in overdensities around the complete quasar samples, quasars with large Ly$\alpha$ nebulae, and control samples, while the most extended nebula appears to be located in the high-density region. Further verification analyses are required since the current dataset lacks spectroscopic confirmation for both quasar nebulae and their surrounding neighbours. Nevertheless, the results demonstrate the great potential of the Rubin LSST to discover giant Ly$\alpha$ nebulae on an unprecedented scale.

The advent of gravitational wave astronomy (GW) has revolutionized the observation of cataclysmic cosmic events, such as black hole mergers and neutron star collisions. The Laser Interferometer Gravitational-Wave Observatory (LIGO) has been at the forefront of these discoveries. However, the immense volume and complexity of gravitational wave data present significant challenges for traditional analysis methods. This paper investigates the growing synergy between artificial intelligence (AI) and GW science, emphasizing how AI enhances signal detection, noise reduction, and data interpretation. It begins with an overview of GW fundamentals and the role of machine learning in increasing detector sensitivity. Notable GW events observed by LIGO are discussed alongside persistent analytical challenges such as data quality, generalization, and computational constraints. A comprehensive performance review of AI techniques, including supervised learning, unsupervised learning, deep learning, and reinforcement learning, is presented based on data spanning 2021 to 2024. Evaluation metrics include accuracy, precision, true positive rate (TPR), false positive rate (FPR), and computational efficiency. Findings indicate that deep learning and supervised learning outperform other approaches, particularly in enhancing TPR and minimizing FPR. While unsupervised and reinforcement learning models offer less precision, they demonstrate high efficiency and potential for real-time applications. The study also explores AI integration into next-generation detectors and waveform reconstruction techniques. Overall, the integration of AI into GW research significantly improves the reliability and speed of event detection, unlocking new possibilities for exploring the dynamic universe. This paper provides a comprehensive outlook on the transformative role of AI in shaping the future of GW astronomy.

Magnetized exoplanets are expected to emit auroral cyclotron radiation in the radio regime due to the interactions between their magnetospheres, the interplanetary magnetic field, and the stellar wind. Prospective extrasolar auroral emission detections will constrain the magnetic properties of exoplanets, allowing the assessment of the planets' habitability and their protection against atmospheric escape by photoevaporation, enhancing our understanding of exoplanet formation and demographics. We construct a numerical model to update the estimates of radio emission characteristics of the confirmed exoplanets while quantifying the uncertainties of our predictions for each system by implementing a Monte Carlo error propagation method. We identify 16 candidates that have expected emission characteristics that render them potentially detectable from current ground-based telescopes. Among these, the hot Jupiter tau Bootis b is the most favorable target with an expected flux density of $51^{+36}_{-22}$ mJy. Notably, eleven candidates are super-Earths and sub-Neptunes, for which magnetism is key to understanding the associated demographics. Together with the other predictive works in the literature regarding the characteristics and the geometry of the magnetospheric emissions, our predictions are expected to guide observational campaigns in pursuit of discovering magnetism on exoplanets.

Atmospheric mass loss is thought to induce the bimodality in the small planet population as we observe it today. Observationally, active mass loss can be traced by excess absorption in spectral lines of lighter species, such as the hydrogen Ly-alpha line and the metastable helium triplet. We search for helium escape from the young (120Myr old) sub-Neptune HIP94235b. We obtained two transit observations of HIP94235b using the CRyogenic InfraRed Echelle Spectrograph (CRIRES+) on the Very Large Telescope (VLT). We find no evidence for escaping helium across both visits, allowing us to place a mass loss rate upper limit of 10^11 g/s, based on 1D Parker wind models. Additionally, we search for molecular spectral features in the planet's transmission spectrum, and cross-correlate our observations with high-resolution template spectra for H2O, the dominating molecule in the Y-band. We detect no significant absorption. We demonstrate that some atmosphere models at 10x solar metallicity would have been retrievable if present. Through the null detection of neutral hydrogen and helium escape, we conclude the atmosphere of HIP94235b likely lacks a large hydrogen-helium envelope. This is consistent with the expectation of small planet photoevaporation models, which suggest most planets lose their primordial hydrogen-helium envelopes within 100Myr of evolution.

V1674 Her is one of the fastest novae, of which the very early phase is well observed including optical rise to the peak over 10 magnitudes. We present a full theoretical light curve model of V1674 Her. Our $1.35~M_\odot$ white dwarf (WD) model with the mass accretion rate of $1\times 10^{-11}~M_\odot$ yr$^{-1}$ explains overall properties including a very fast rise and decay of the optical $V$ light curve. The WD photosphere expands up to $21 ~R_\odot$, thus, a $0.26 ~M_\odot$ companion star orbiting the WD every 3.67 hours, is engulfed 2.7 hours after the onset of thermonuclear runaway, and appears 5.3 days after that. The duration of X-ray flash is only 0.96 hours. The evolution of the expanding envelope and temporal change of the photospheric radius are very consistent with observed optical and X-ray modulations with the orbital and spin (501 s) periods. We confirmed that the decay phase of nova light curve is well approximated by a sequence of steady-state envelope solutions. Using time-stretching method of nova light curves, we obtain the $V$ band distance modulus of $(m-M)_V= 16.3\pm 0.2$, and determine the distance to be $d=8.9\pm 1$ kpc for the interstellar extinction of $E(B-V)= 0.5 \pm 0.05$.

We conducted a detailed analysis of the jet structure and dynamics of the source 0241+622 on milliarcsecond (mas) scales. We stacked images from multiple epochs to better recover the crosssection of the jet. By analyzing the relationship between jet width and distance, we observed that the jet exhibits a parabolic shape from the core, spanning a region from 0.12 to 6.1 mas. This structure suggests the acceleration and collimation processes of the jet. Beyond 18 mas from the core, the jet adopts a conical shape, and the expansion speed of the jet becomes faster within the range from 4500 to 6500 mas. We obtained the core shift of this source using five pairs of data from VLBA at 1.6 GHz to 43 GHz. Based on previous studies, through proper motion analysis of the jet components, we estimated the angle between the jet and the line of sight to be approximately 65.7°, so 1 mas corresponds to 0.95 pc (de-projected distance). We then obtained the velocity field of the source within 3.14 mas from the central black hole and found that the jet exhibits accelerated motion within this range. At approximately 6.1 mas from the core, we observed that the jet width begins to decrease, which we identified as possibly corresponding to the Bondi radius of this source. The reduction in jet width may be related to changes in the external environmental pressure, particularly within the Bondi radius, indicating that the jet dynamics and collimation characteristics are strongly influenced by the surrounding medium conditions.

Galaxy clustering is an important probe in the upcoming China Space Station Telescope (CSST) survey to understand the structure growth and reveal the nature of the dark sector. However, it is a long-term challenge to model this biased tracer and connect the observable to the underlying physics. In this work, we present a hybrid Lagrangian bias expansion emulator, combining the Lagrangian bias expansion and the accurate dynamical evolution from $N$-body simulation, to predict the power spectrum of the biased tracer in real space. We employ the Kun simulation suite to construct the emulator, emulating across the space of 8 cosmological parameters including dynamic dark energy $w_0$, $w_a$, and total neutrino mass $\sum m_{\nu}$. The sample variance due to the finite simulation box is further reduced using the Zel'dovich variance control, and it enables the precise measurement of the Lagrangian basis spectra up to quadratic order. The emulation of basis spectra realizes 1% level accuracy, covering wavelength $ k \leq 1 \,{\rm Mpc}^{-1}h$ and redshift $0\leq z\leq 3$ up to quadratic order field. To validate the emulator, we perform the joint fitting of the halo auto power spectrum and the halo-matter cross power spectrum from 46 independent simulations. Depending on the choice of counterpart, the joint fitting is unbiased up to $k_{\rm max}\simeq 0.7\,{\rm Mpc}^{-1}h$ with $1\sim 2$ percent accuracy, for all the redshift and halo mass samples. As one of the CSST cosmological emulator series, our emulator is expected to provide accurate theoretical predictions of the galaxy power spectrum for the upcoming CSST survey.

Recent studies using the Gaia DR3 data have revealed a two-armed phase spiral in the $Z-V_Z$ phase space in the inner disk. In this study, we present new features of the two-armed phase spiral revealed by the Gaia Data and a new mechanism to explain such features with multiple external perturbations. By segmenting the Gaia DR3 RVS catalog based on $J_{\phi}$ (or $R_{g}$) and $\theta_\phi$, we confirm the existence of the clear two-armed phase spiral in the inner disk. Moreover, we identify a different two-armed phase spiral pattern at slightly larger radii, resembling a weak secondary branch along with the prominent major branch. At a given radius, with the azimuthal angle increasing, we observe a systematic transition of the two-armed phase spiral, with the significance of one branch weakened and another branch enhanced. This two-armed phase spiral may be due to the overlapping of distinct one-armed phase spirals. At different radii, the perturbation times estimated from each branch of the two-armed phase spiral are $\sim 320$ Myr and $\sim 500$ Myr, respectively, suggesting that the Galactic disk could be impacted by double external perturbers separated by $\sim 180$ Myr. We also performed test particle simulations of the disk perturbed by two satellite galaxies, which successfully generated a two-armed phase spiral similar to the observation. Both the observation and simulation results suggest that the signature in the $Z-V_Z$ phase space of earlier perturbations may not be completely erased by the more recent one.

Gamma-ray bursts (GRBs) are a promising probe of the high-redshift Universe, but their detection remains observationally challenging. In this work, we explore the detectability of high-$z$ GRBs by the Wide-field X-ray Telescope (WXT) aboard the Einstein Probe (\emph{EP}) and the coded-mask gamma-ray imager (ECLAIRs) aboard the Space-based multi-band astronomical Variable Objects Monitor (\emph{SVOM}). Using a population synthesis model calibrated to $Swift$ GRB observations, we develop a tool to estimate high-$z$ GRB detection rates for instruments with specific energy bands and sensitivities. Our results indicate that \emph{EP}/WXT could detect $\sim5.1^{+3.4}_{-2.4}$ (with 68\% confidence level) GRBs annually at $z>6$, compared to $\sim0.7^{+1.0}_{-0.4}$ $\mathrm{events\,yr^{-1}}$ at $z>6$ for \emph{SVOM}/ECLAIRs. While \emph{EP} cannot independently determine redshifts (requiring optical/near-infrared follow-up), its assumed $\sim30\%$ follow-up efficiency yields $\sim1.5^{+1.0}_{-0.7}$ confirmed $z>6$ GRBs annually. \emph{SVOM}, equipped with dedicated follow-up telescopes, will ensure robust high-$z$ GRB confirmations. We anticipate that \emph{EP} and \emph{SVOM} will open new avenues for utilizing enlarged samples of high-$z$ GRBs to explore the early Universe. Moreover, \emph{EP} will assemble a substantial sample of soft, low-luminosity GRBs at low-to-intermediate redshifts, providing critical insights into the structure of GRB jets.

The most recent observational and theoretical results in the rapidly expanding field of high-energy gamma-ray astrophysics were discussed at the international conference ``Gamma-2024'' that took place in Milano in September 2024. This contribution summarises the 'rapporteur talk' relative to the Galactic science given at the end of the conference.

Photons emitted by primordial black holes (PBHs) due to the Hawking effect are among the factors of interstellar dust heating. Based on the data on the temperature of dust, constraints on the fraction of $10^{15}\leq M\leq10^{17}$~g.

Feedback from supernovae and AGN shapes galaxy formation and evolution, yet its impact remains unclear. Galaxy groups offer a crucial probe, as their binding energy is comparable to that available from their central AGN. The XMM-Newton Group AGN Project (X-GAP) is a sample of 49 groups selected in X-ray (ROSAT) and optical (SDSS) bands, providing a benchmark for hydrodynamical simulations. In sight of such a comparison, understanding selection effects is essential. We aim to model the selection function of X-GAP by forward modelling the detection process in the X-ray and optical bands. Using the Uchuu simulation, we build a halo light cone, predict X-ray group properties with a neural network trained on hydro simulations, and assign galaxies matching observed properties. We compare the selected sample to the parent population. Our method provides a sample that matches the observed distribution of X-ray luminosity and velocity dispersion. The 50% completeness is reached at a velocity dispersion of 450 km/s in the X-GAP redshift range. The selection is driven by X-ray flux, with secondary dependence on velocity dispersion and redshift. We estimate a 93% purity level in the X-GAP parent sample. We calibrate the velocity dispersion-halo mass relation. We find a normalisation and slope in agreement with the literature, and an intrinsic scatter of about 0.06 dex. The measured velocity dispersion is accurate within 10% only for rich systems with more than about 20 members, while the velocity dispersion for groups with less than 10 members is biased at more than 20%. The X-ray follow-up refines the optical selection, enhancing purity but reducing completeness. In an SDSS-like setup, velocity dispersion measurement errors dominate over intrinsic scatter. Our selection model will enable the comparisons of thermodynamic properties and gas fractions between X-GAP groups and hydro simulations.

The appearance of blue loops in the evolutionary tracks of intermediate-mass core He-burning stars is essential for explaining the observed characteristics of Cepheids. The blue loops for lower mass Cepheids cannot always be reproduced when only classical, local mixing length theory (MLT) is used. Additionally, classical models result in a mass discrepancy compared to pulsational and dynamical mass determinations. Both problems can be resolved through an ad-hoc extension of the MLT for convection. We use the non-local Kuhfuss turbulent convection model (TCM) which can explain overshooting directly from the solution of the TCM equations. The primary objective of this study is to test the predictions of the Kuhfuss TCM when applied to intermediate-mass core He-burning stars and validate the model predictions against observations of Cepheids. We used the state-of-the-art 1D stellar evolution code GARSTEC with the implementation of the Kuhfuss TCM and computed evolutionary tracks for intermediate-mass core He-burning stars. We compare these tracks with those computed with MLT including and excluding ad-hoc overshooting and with observations of five Cepheids in detached binary systems obtained from the literature. The stellar evolution tracks generated using the Kuhfuss TCM and MLT with ad-hoc overshooting exhibit similar appearances. Overshoot mixing from the convective boundaries and the occurrence of the Cepheid blue-loop have been achieved naturally as solutions to the Kuhfuss TCM equations. Furthermore, these models successfully reproduce observed stellar parameters including mass, luminosity, radius, and effective temperature. In conclusion, our TCM approach reproduces Cepheid blue loops and agrees with observations similarly well as MLT models with overshooting, however, without fine-tuning the model parameters or ad-hoc assumptions.

The central supermassive black hole (SMBH) of the Andromeda galaxy, known as M31*, exhibits dim electromagnetic emission and is inferred to have an extremely low accretion rate for its remarkable mass ($\sim10^8~\rm~M_\odot$). In this work, we use three-dimensional hydrodynamical simulations to explore a previously untested scenario, in which M31* is fed by the collective stellar mass-loss from its surrounding nuclear star cluster, manifested as a famous eccentric disk of predominantly old stellar populations. The stellar mass-loss is assumed to be dominated by the slow and cold winds from 100 asymptotic giant-branch stars, which follow well-constrained Keplerian orbits around M31* and together provide a mass injection rate of $\sim4\times10^{-5}\rm~M_\odot~yr^{-1}$. The simulations achieve a quasi-steady state on a Myr timescale, at which point a quasi-Keplerian, cool ($T\sim10^3-10^4~\rm K$) gas disk extending several parsecs is established. This disk is continuously supplied by the stellar winds and itself feeds the central SMBH. At the end of the simulations at 2 Myr, an accretion rate of $\sim2\times10^{-5}\rm~M_\odot~yr^{-1}$ is found but could vary by a factor of few depending on whether the subdominant gravity of the NSC or a moderate global inflow is included. The predicted X-ray luminosity of $\sim10^{36}~\rm erg~s^{-1}$, dominated by the hot ($T\sim10^7-10^8~\rm K$) plasma within 0.2 parsec of the SMBH, is well consistent with Chandra observations. We conclude that the feeding mechanism of M31* is successfully identified, which has important implications for the working of dormant SMBHs prevalent in the local universe.

Large aperture ground based solar telescopes allow the solar atmosphere to be resolved in unprecedented detail. However, observations are limited by Earths turbulent atmosphere, requiring post image corrections. Current reconstruction methods using short exposure bursts face challenges with strong turbulence and high computational costs. We introduce a deep learning approach that reconstructs 100 short exposure images into one high quality image in real time. Using unpaired image to image translation, our model is trained on degraded bursts with speckle reconstructions as references, improving robustness and generalization. Our method shows an improved robustness in terms of perceptual quality, especially when speckle reconstructions show artifacts. An evaluation with a varying number of images per burst demonstrates that our method makes efficient use of the combined image information and achieves the best reconstructions when provided with the full image burst.

Reactions involving atomic carbon in its ground electronic state, C(3P), play an important role in astrochemistry due to high C-atom abundance levels. Here we performed a kinetic investigation of the reaction between C(3P) and acetaldehyde, CH3CHO, determining rate constants for this process over the 50-296 K range. Measurements of the formation of atomic hydrogen, H(2S), were also performed to provide insight into product formation. Experiments were conducted using a supersonic flow reactor coupled with pulsed laser photolysis for C-atom generation and pulsed laser induced fluorescence in the vacuum ultraviolet range for the detection of both C(3P) and H(2S) atoms. Quantum chemical calculations of the ground triplet state potential energy surface of C3H4O were also performed to provide theoretical support for the measurements. The rate constants were large and temperature independent with an average value of 4.0 x 10-10 cm3 s-1. This result is consistent with the theoretical results which predict either very low barriers or none at all on the underlying potential energy surface. Although experimental difficulties prevented the quantitative determination of H-atom formation, qualitatively, H-atom yields were very low with CH3CH/C2H4 + CO as the major products based on the calculations. The influence of this reaction on interstellar chemistry was tested using a gas-grain model of dense interstellar clouds. These simulations predict that the C(3P) + CH3CHO reaction decreases gas-phase CH3CHO abundances by more than an order of magnitude at early and intermediate cloud ages, with a lower influence at typical dense cloud ages.

Being the most energetic events in the known universe, the impact of galaxy cluster mergers on the properties of the resident galaxies has yet to be well-understood. In this paper, we investigate the effects of merging environments on star formation in nearby clusters ($0.04<z<0.06$) from the SAMI Galaxy Survey - A168, A2399, A3380, and EDCC 0442 - which exhibit different dynamical activity. Using single-fiber spectroscopy from the SAMI Cluster Redshift Survey (SAMI-CRS) and Sloan Digital Sky Survey (SDSS), we trace star formation (SF) activity across the cluster sample by identifying the star-forming galaxy (SFG) population based on spectral features. We find a mild enhancement in the star-forming galaxy fraction $f_{SFG}$ in merging clusters, although not statistically significant. The spatial and projected phase-space distributions show that SFGs in merging clusters are well-mixed with the passive population, while galaxy populations exhibit a clear segregation in the relaxed clusters. Analysis of equivalent width of $\rm H\alpha$ line (EW($\rm H\alpha$)), as a tracer of recent SF activity, does not reveal strong evidence of triggered star formation activity as a function of dynamical state for both the global cluster environment and subsamples of galaxies selected near possible merger features. This suggests that the increase in $f_{SFG}$ is due to the mixing of galaxies in dynamically complex, young merging systems that are still forming, unlike their older, relaxed counterparts that have had longer to quench.

We investigate the origin of NGC 5634 through a comprehensive analysis of its morphology, kinematics and dynamics. Utilizing data from the DESI Legacy Survey, we refined its fundamental parameters (age t = 12.8 +/- 0.3 Gyr, metallicity [Fe/H] = -1.8 +/- 0.1 dex, distance modulus dm = 17.0 +/- 0.1 mag) and constructed matched-filter template based on the combination of these parameters to search for extra-tidal structures. However, no significant features were detected above a 3 sigma signal-to-noise threshold, which limits our ability to further investigate the association between NGC 5634 and the Sagittarius (Sgr) stream based on morphological evidence. Incorporating GAIA data, we further examine the orbital path of NGC 5634. We found that its orbit only briefly intersects with the Sgr stream and diverges significantly over long-term integrations. This behavior contrasts with that of confirmed Sgr-associated clusters, whose orbits remain closely aligned with the stream throughout their orbital evolution. Additionally, NGC 5634 exhibits a relatively shorter semi-major axis and smaller apocenter and pericenter distances compared to Sgr clusters. These orbital characteristics are more consistent with clusters associated with the Gaia-Sausage-Enceladus (GSE) or the Helmi streams. From a dynamical perspective, in the Lz-E space, NGC 5634 is also distinctly different from Sgr clusters and aligns more closely with the GSE and Helmi regions. Taken together, these findings do not support a strong connection between NGC 5634 and the Sgr dSph, but instead suggest a potential association with another progenitor system, such as GSE or Helmi stream. Nevertheless, further evidence is needed to definitively establish its origin.

Coronal dimmings are regions of transiently reduced brightness in extreme ultraviolet (EUV) and soft X-ray (SXR) emissions associated with coronal mass ejections (CMEs), providing key insights into CME initiation and early evolution. During May 2024, AR 13664 was among the most flare-productive regions in recent decades, generating 55 M-class and 12 X-class flares along with multiple Earth-directed CMEs. The rapid succession of these CMEs triggered the most intense geomagnetic storm in two decades. We study coronal dimmings from a single active region (AR 13664) and compare them with statistical dimming properties. We investigate how coronal dimming parameters - such as area, brightness, and magnetic flux - relate to key flare and CME properties. We systematically identified all flares above M1.0, all coronal dimmings and all CMEs (from the CDAW SOHO/LASCO catalogue) produced by AR 13664 during 2024 May 1 - 15, and studied the associations between the different phenomena and their characteristic parameters. We detect coronal dimmings in 22 events, with 16 occurring on-disc and six off-limb. Approximately 83% of X-class flares and 23% of M-class flares are associated with CMEs, with 13 out of 16 on-disc dimmings linked to CME activity. Our results support the strong interplay between coronal dimmings and flares, as we find increased correlations between flare and dimming parameters in this single-AR study compared to the general dimming population. Furthermore, we confirm that coronagraphic observations, unable to observe the lower corona, underestimate correlations between CME velocities and dimming parameters, as they fail to capture the early CME acceleration phase. This highlights the critical role of dimming observations in providing a more comprehensive understanding of CME dynamics.

The proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae has gained considerable support recently with the addition of five new HIIGx discovered by JWST. The updated sample of 231 sources now extends the redshift range of these objects to $z\sim 7.5$, mapping the Universe's expansion over $95\%$ of its current age. In this {\it Letter} we use these sources for model selection, and show that the $R_{\rm h}=ct$ universe is strongly favored by this probe over both flat-$\Lambda$CDM and $w$CDM, with relative Bayesian Information Criterion probabilities of, respectively, $91.8\%$, $7.4\%$ and $0.8\%$. A possible caveat with these results, however, is that an unknown dispersion, $\sigma_{\rm int}$, in the HIIGx standard candle relation can weaken the model comparisons. We find that the inclusion of $\sigma_{\rm int}$ as an additional, optimizable parameter makes the likelihoods of flat-$\Lambda$CDM and $R_{\rm h}=ct$ about equal, though at the expense of creating $\sim 2.5\sigma$ tension between our inferred matter density $\Omega_{\rm m}$ and its {\it Planck}-optimized value.

Context. The high precision of recent asteroseismic observations of red-giant stars has revealed the presence of mixed dipole modes in their oscillation spectra. These modes allow for a look inside the stars. Among the parameters used to characterize mixed modes is the coupling strength q, which is sensitive to the stellar structure in the evanescent zone near the bottom of the convective envelope. Aims. The aim of this work is to probe the validity of the weak and strong coupling approximations, commonly used to calculate q, during stellar evolution along the red-giant branch (RGB). Methods. To test the approximations empirically, we calculate q-values in both, the weak and strong limit for stellar models on the RGB and compare them to the coupling derived from the mixed mode frequency pattern obtained from numerical solutions to the oscillation equations. Results. We find good agreement with the strong coupling approximation on the early RGB, when the evanescent zone lies in the radiative layer right above the hydrogen-burning shell; and with the weak coupling approximation once the evanescent zone is situated in the convective envelope. This is consistent with earlier studies. Additionally, we find that it is viable to use the weak coupling approximation as an estimate for q in the intermediate regime, in the mass range considered in this work (1.00 Msun <= M <= 2.00 Msun). Conclusions. The width of the evanescent zone serves as a good measure for which approximation to use. The serendipitous alignment of the weak coupling approximation with the observable q in the regime where neither approximation is expected to be valid simplifies the asymptotic calculation of mixed mode properties.

The Chinese Pulsar Timing Array (CPTA) has collected observations from 57 millisecond pulsars using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) for close to three years, for the purpose of searching for gravitational waves (GWs). To robustly search for ultra-low-frequency GWs, pulsar timing arrays (PTAs) need to use models to describe the noise from the individual pulsars. We report on the results from the single pulsar noise analysis of the CPTA data release I (DR1). Conventionally, power laws in the frequency domain are used to describe pulsar red noise and dispersion measurement (DM) variations over time. Employing Bayesian methods, we found the choice of number and range of frequency bins with the highest evidence for each pulsar individually. A comparison between a dataset using DM piecewise measured (DMX) values and a power-law Gaussian process to describe the DM variations shows strong Bayesian evidence in favour of the power-law model. Furthermore, we demonstrate that the constraints obtained from four independent software packages are very consistent with each other. The short time span of the CPTA DR1, paired with the large sensitivity of FAST, has proved to be a challenge for the conventional noise model using a power law. This mainly shows in the difficulty to separate different noise terms due to their covariances with each other. Nineteen pulsars are found to display covariances between the short-term white noise and long-term red and DM noise. With future CPTA datasets, we expect that the degeneracy can be broken. Finally, we compared the CPTA DR1 results against the noise properties found by other PTA collaborations. While we can see broad agreement, there is some tension between different PTA datasets for some of the overlapping pulsars. This could be due to the differences in the methods and frequency range compared to the other PTAs.

Ultralight axion-like dark matter (ALDM) is a leading candidate in the dark matter realm, characterized by its prominent wave properties on astronomical scales. Pulsar Timing Arrays (PTAs) and Pulsar Polarization Arrays (PPAs) aim to detect this dark matter through timing and polarization measurements, respectively, of pulsars. The PTA relies on gravitational effects, as the ALDM halo perturbs the spacetime metric within the Milky Way, while the PPA detects non-gravitational effects, namely cosmological birefringence induced by the ALDM Chern-Simons coupling with photons. These two methods complement each other, synergistically enhancing the pulsar array's capability to identify the ALDM signals in the data. In this article, we provide a foundational development of this synergy. We begin by revisiting previously derived two-point correlation functions for both PTA and PPA, and expand our analysis to include correlations between timing and polarization signals. We then construct likelihood functions for PTA and combined PTA-PPA analyses within a Bayesian framework, aimed at detecting the characteristic correlations of ALDM signals. We emphasize the non-Gaussianity of the ALDM timing signals, which arises from their non-linear dependence on the field, in contrast to the Gaussian nature of its polarization signals. To address the complexities introduced, we approach this investigation in two ways: one involves a Gaussian approximation with proper justifications, while the other derives the formalism from the generic Gaussian characteristics of the ALDM field. We anticipate that these efforts will lead to further developments in PTA and PTA-PPA analysis methods.

We derive the full covariance matrix formulae are derived for proper treatment of correlations in signal fitting procedures, extending the results from previous publications. The straight line fits performed with these matrices demonstrate that a significantly higher signal to noise is obtained when the fluence exceeds 1 e/sec/pix in particular in long (several hundreds of seconds) spectroscopic exposures. The improvement arising from the covariance matrix is particularly strong for the initial intercept of the fit at t=0, a quantity which provides a useful redundancy to cross check the signal quality. We demonstrate that the mode that maximizes the signal to noise ratio in all ranges of fluxes studied in this paper is the one that uses all the frames sampled during the exposure. While at low flux there is no restriction on the organization of frames within groups for fluxes lower than 1 e/sec/pix, for fluxes exceeding this value the coadding of frames shell be avoided.

We present photometric time series data spanning 2018-2024 that show the effects of temporal dynamics in the binary system KH 15D, a member of the NGC 2264 star forming region. This source exhibits complex eclipsing behavior due to a precessing circumbinary disk or ring that is slightly inclined relative to the orbital plane of the binary. Using g-band and r-band observations from the Zwicky Transient Facility (ZTF) over seven observing seasons, we follow the evolution of the KH 15D lightcurve as it continues to emerge from its deepest observed photometric minimum about 15 years ago. Our observations are consistent with previous models that propose a precessing, warped circumbinary disk orbiting KH 15D. We verify the gradual precession of the disk by quantifying the times of eclipse ingresses and egresses. We also examine the central re-brightening within the minima of the phased lightcurve. This feature has increased in amplitude over our observing seasons, and we measure its evolution in both amplitude and phase from year to year. Finally, we assess color as a function of phase and brightness. Our findings support the assertion that line-of-sight variations in disk density and structure, possibly due to clumping, coupled with a precessing circumbinary disk are responsible for the central re-brightening event.

Albeit at a lower frequency than around hotter stars, short-period gas giants around low-mass stars ($T_\mathrm{eff} < 4965$ K) do exist, despite predictions from planetary population synthesis models that such systems should be exceedingly rare. By combining data from TESS and ground-based follow-up observations, we seek to confirm and characterize giant planets transiting K dwarfs, particularly mid/late K dwarfs. Photometric data were obtained from the TESS mission, supplemented by ground-based imaging- and photometric observations, as well as high-resolution spectroscopic data from the CORALIE spectrograph. Radial velocity (RV) measurements were analyzed to confirm the presence of companions. We report the confirmation and characterization of three giants transiting mid-K dwarfs. Within the TOI-2969 system, a giant planet of $1.16\pm 0.04\,M_\mathrm{Jup}$ and a radius of $1.10 \pm 0.08\,R_\mathrm{Jup}$ revolves around its K3V host in 1.82 days. The system of TOI-2989 contains a $3.0 \pm 0.2\,M_\mathrm{Jup}$ giant with a radius of $1.12 \pm 0.05\,R_\mathrm{Jup}$, which orbits its K4V host in 3.12 days. The K4V TOI-5300 hosts a giant of $0.6 \pm 0.1\,M_\mathrm{Jup}$ with a radius of $0.88 \pm 0.08\,R_\mathrm{Jup}$ and an orbital period of 2.3 days. The equilibrium temperatures of the companions range from 1001 to 1186 K, classifying them as Hot Jupiters. However, they do not present radius inflation. The estimated heavy element masses in their interior, inferred from the mass, radius, and evolutionary models, are $90 \pm 30\,M_\oplus$, $114 \pm 30\,M_\oplus$, and $84 \pm 21\,M_\oplus$, respectively. The heavy element masses are significantly higher than most reported heavy elements for K-dwarf Hot Jupiters. These mass characterizations contribute to the poorly explored population of massive companions around low-mass stars.

Fast radio bursts (FRBs) are enigmatic extragalactic radio transients with unknown origins. We performed comprehensive Monte Carlo simulations based on the first CHIME/FRB catalog to test whether the FRB population tracks the cosmic star formation history directly or requires a delay. By fully considering CHIME's complex selection effects and beam response, we find that the hypothesis that the FRB population tracks the SFH is not ruled out by the current data, although a small delay is preferred. This is consistent with the scenario in which young magnetars formed through core-collapse supernovae serve as the progenitors of FRBs. However, we estimate the local volumetric rate of FRB sources with energy above $10^{38}$ erg to be $2.3^{+2.4}_{-1.2} \times 10^5~\rm{Gpc}^{-3}~\rm{yr}^{-1}$, which is consistent with previous results. This high volumetric rate means the core-collapse magnetar scenario alone cannot fully account for the observed population. Further theoretical efforts are required to explore alternative or additional progenitor channels for FRBs.

A new generation of optical intensity interferometers are emerging in recent years taking advantage of the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC SII (Stellar Intensity Interferometer) in La Palma, Spain, has been operating since its first successful measurements in 2019 and its current design allows it to operate regularly. The current setup is ready to follow up on bright optical transients, as changing from regular gamma-ray observations to SII mode can be done in a matter of minutes. A paper studying the system performance, first measurements and future upgrades has been recently published. MAGIC SII's first scientific results are the measurement of the angular size of 22 stars, 13 of which with no previous measurements in the B band. More recently the Large Sized Telescope prototype from the Cherenkov Telescope Array Observatory (CTAOLST1) has been upgraded to operate together with MAGIC as a SII, leading to its first correlation measurements at the beginning of 2024. MAGIC+CTAO-LST1 SII will be further upgraded by adding the remaining CTAOLSTs at the north site to the system (which are foreseen to be built by the end of 2025). MAGIC+CTAO-LST1 SII shows a feasible technical solution to extend SII to the whole CTAO.

We present the readout noise reduction methods and the 1/f noise response of an 2Kx2K HgCdTe detector similar to the detectors that will be used in the Near Infrared Spectrometer Photometer - one of the instruments of the future ESA mission named Euclid. Various algorithms of common modes subtraction are defined and compared. We show that the readout noise can be lowered by 60% using properly the references provided within the array. A predictive model of the 1/f noise with a given frequency power spectrum is defined and compared to data taken in a wide range of sampling frequencies. In view of this model the definition of ad-hoc readout noises for different sampling can be avoided

Euclid mission is designed to understand the dark sector of the universe. Precise redshift measurements are provided by H2RG detectors. We propose an unbiased method of fitting the flux with Poisson distributed and correlated data, which has an analytic solution and provides a reliable quality factor - fundamental features to ensure the goals of the mission. We compare our method to other techniques of signal estimation and illustrate the anomaly detection on the flight like detectors. Although our discussion is focused on Euclid NISP instrument, much of what is discussed will be of interest to any mission using similar near-infrared sensors

We report seismic analyses of five pulsating subdwarf B (sdBV) stars observed during Kepler's K2 mission, each with a white dwarf companion. We find three of the five to be g-mode-dominated hybrid pulsators. For the other two, we only detect g modes. We determine rotation periods from frequency multiplets for four stars and each rotates subsynchronously to its binary period, including PG 0101+039 and PG 0902+124 both with binary periods near 0.57 days and spin periods near 9 days. We detect frequency multiplets in both p and g modes for PG 0101+039 and LT Cnc and determine that PG 0101+039 rotates like a solid body while LT Cnc rotates differentially radially with the envelope spinning faster than deeper layers. Mostly we find these five stars to be quite similar to one another, spectroscopically and seismically. We find the p modes of the three hybrid pulsators to have gaps between regions of power, which we interpret as overtones and apply a technique to assign modes. We examine their g mode period spacings and deviations thereof and again, find the stars to be similar with period spacings near the average of 250 s and deviations mostly under 25 s. We compare Kepler-observed sdBV stars of different binary types and likely-single pulsators.

Wide Binaries (WBs) are interesting systems to test Newton-Einstein gravity in low potentials. The basic concept is to verify whether the difference in velocity between the WB components is compatible with what is expected from the Newton law. Previous attempts, based solely on Gaia proper motion differences scaled to transverse velocity differences using mean parallax distances, do not provide conclusive results. Here we add to the Gaia transverse velocities precise measurements of the third velocity component, the radial velocity (RV), in order to identify multiple stars, and to improve the reliability of the test by using velocity differences and positions in three dimensions. We use the HARPS spectra to determine accurate RV difference between the WB components, correcting the observed velocities for gravitational redshift and convective shift. We exploit the Gaia distance distributions to determine the projected and intrinsic separations s and r and the 3-dimensional velocity differences of the binaries. Of the 44 pairs observed with HARPS, 27% show sign of multiplicity or are not suitable for the test, and 32 bona-fide WBs survive our selection. Their projected separation s is up to 14 kAU, or 0.06 parsec. We determine distances, eccentricities and position angles to reproduce the velocity differences according to Newton's law, finding reasonable solutions for all WBs but one, and with some systems possibly too near pericenter and/or at too high inclination. Our (limited) number of WBs does not show obvious trends with separation or acceleration and is consistent with Newtonian dynamics. We are collecting a larger sample of this kind to robustly assess these results.

Recent works have found evidence of significant intrasystem uniformity in planet properties such as radius, mass, and orbital spacing, collectively termed 'peas in a pod' trends. In particular, correlations in radius and mass have been interpreted as implying uniformity in planet bulk density and composition within a system. However, the samples used to assess trends in mass tend to be small and biased. In this paper, we re-evaluate correlations in planet properties in a large sample of systems with at least two planets for which mass and radius have been directly measured, and therefore bulk density can be calculated. Our sample was assembled using the most up-to-date exoplanet catalogue data, and we compute the relevant statistics while using a procedure to 'weight' the data points according to measurement precision. We find a moderate correlation in radius and a weak correlation in the densities of adjacent planets. However, masses of neighbouring planets show no overall correlation in our main sample and a weak correlation among pairs of planets similar in size or pairs restricted to Mp<100 M_Earth, Rp<10 R_Earth. Similarly, we show that the intrasystem dispersion in radius is typically less than that in mass and density. We identify ranges in stellar host properties that correlate with stronger uniformity in pairs of adjacent planets: low Teff for planet masses, and low metallicity and old age for planet densities. Furthermore, we explore whether peas in a pod trends extend into planet compositions or interior structures. For small neighbouring planets with similar radii, we show that their masses and interior structures are often disparate, indicating that even within the same system, similarity in radii is not necessarily a good proxy for similarity in composition or the physical nature of the planets.

We present a cosmology analysis of weak lensing convergence maps using the Neural Field Scattering Transform (NFST) to constrain cosmological parameters. The NFST extends the Wavelet Scattering Transform (WST) by incorporating trainable neural field filters while preserving rotational and translational symmetries. This setup balances flexibility with robustness, ideal for learning in limited training data regimes. We apply the NFST to 500 simulations from the CosmoGrid suite, each providing a total of 1000 square degrees of noiseless weak lensing convergence maps. We use the resulting learned field compression to model the posterior over $\Omega_m$, $\sigma_8$, and $w$ in a $w$CDM cosmology. The NFST consistently outperforms the WST benchmark, achieving a 16% increase in the average posterior probability density assigned to test data. Further, the NFST improves direct parameter prediction precision on $\sigma_8$ by 6% and w by 11%. We also introduce a new visualization technique to interpret the learned filters in physical space and show that the NFST adapts its feature extraction to capture task-specific information. These results establish the NFST as a promising tool for extracting maximal cosmological information from the non-Gaussian information in upcoming large-scale structure surveys, without requiring large simulated training datasets.

T~Coronae Borealis is the nearest symbiotic recurrent nova. Twice in the last two centuries, in 1866 and 1946, the accreted material ignited on the surface of the white dwarf via runaway thermonuclear fusion reactions and produced a nova eruption. Both eruptions occurred approximately midway through a transient state of high luminosity. A possible explanation of such a state is a dwarf-nova-like outburst, which may arise from a transient increase in the mass-transfer rate of the donor star. We simulate the response of an accretion disk to an event of enhanced mass-transfer that is ``interrupted'' by a pre-eruption dip associated to the convective phase leading to the thermonuclear runaway, and model the resulting optical light curve using the parameters of the T~CrB binary. Our model represents the first attempt to reproduce the transient high-accretion state. The observed brightening can be satisfactorily reproduced by models of an accretion disk with a viscosity parameter $\alpha = 3$, an event of enhanced mass-transfer with a duration of $\Delta t = 15$\,yr, and quiescent and high-state mass-transfer rates of $2.0 \times 10^{-9} \, M_\odot$\,yr$^{-1}$ and $1.9 \times 10^{-7} \, M_\odot$\,yr$^{-1}$, respectively, while the pre-eruption dip can be reproduced by the small, accelerated expansion of the inner disk radius, at an average velocity of 0.02\,km\,s$^{-1}$. Our model is also capable of reproducing the observed changes in color of T~CrB throughout the transient event.

Context. Determining the ages of young stellar systems is fundamental to test and validate current star-formation theories. Aims. We aim at developing a Bayesian version of the expansion rate method that incorporates the a priori knowledge on the stellar system's age and solves some of the caveats of the traditional frequentist approach. Methods. We upgrade an existing Bayesian hierarchical model with additional parameter hierarchies that include, amongst others, the system's age. For this later, we propose prior distributions inspired by literature works. Results. We validate our method on a set of extensive simulations mimicking the properties of real stellar systems. In stellar associations between 10 and 40 Myr and up to 150 pc the errors are <10%. In star forming regions up to 400 pc, the error can be as large as 80% at 3 Myr but it rapidly decreases with increasing age. Conclusions. The Bayesian expansion rate methodology that we present here offers several advantages over the traditional frequentist version. In particular, the Bayesian age estimator is more robust and credible than the commonly used the frequentist ones. This new Bayesian expansion rate method is made publicly available as a module of the free and open-source code Kalkayotl.

Context. Local young stellar associations (LYSAs <50 Myr and <150 pc) are important laboratories to test predictions from star-formation theories. Estimating their ages through various dating techniques with minimal biases is thus of paramount importance. Aims. We aim at determining the ages of LYSAs with the expansion rate dating technique. Methods. We estimate the ages of the LYSAs using literature membership lists, publicly available data (astrometry and radial velocities), and a recent open-source Bayesian code that implements the expansion rate method. This code in combination with simple statistical assumptions allow us to decontaminate, identify possible substructures or populations, and estimate expansion ages. Results. We derive the largest and most methodological homogeneous set of ages of LYSAs. We rediscover three and discover four associations hidden within the literature membership lists of the classical ones. Conclusions. The expansion ages we report here are compatible with literature age estimates. Moreover, our analysis shows that previous age tensions can be explained, in most cases, by the presence of unidentified populations or substructures.

We discuss the requirements, concepts, simulations, implementation, and calibration of two dual Fabry-Perot based imaging spectropolarimeters, CRISP and CHROMIS, at the Swedish 1-meter Solar Telescope, and CRISP2 that is under construction. These instruments use a combination of a high-resolution and a low-resolution etalon together with an order-sorting prefilter to define the bandpass. The overall design is made robust and stable by tailoring the low-resolution etalon reflectivity to accommodate expected cavity errors from both etalons, and by using a compact optical design that eliminates the need for folding mirrors. By using a telecentric design based on lenses rather than mirrors, image degradation by the FPI system is negligible, as shown in a previous publication, and the throughput of the system is maximised. Initial alignment, and maintaining that alignment over time, is greatly simplified. The telecentric design allows full calibration and/or modelling of essential system parameters to be carried out without interfering with the optical setup. We also discuss briefly the polarimeters developed for CRISP and CHROMIS. The high performance of CRISP and CHROMIS has been demonstrated in an earlier publication through measurements of the granulation contrast and comparisons with similar measurements simultaneously made through broadband continuum filters. Here, we focus on the aspects of the design that are central to enabling high performance and robustness, but also discuss the calibration and processing of the data, and use a few examples of processed data to demonstrate the achievable image and data quality. We put forward a proposal for a similar conceptual design for the European Solar Telescope and conclude by discussing potential problems of the proposed approach to designs of this type. Some aspects of these FPI systems may be of interest also outside the solar community.

We present DELTA (Data-Empiric Learned Tidal Alignments), a deep learning model that isolates galaxy intrinsic alignments (IAs) from weak lensing distortions using only observational data. The model uses an Equivariant Graph Neural Network backbone suitable for capturing information from the local galaxy environment, in conjunction with a probabilistic orientation output. Unlike parametric models, DELTA flexibly learns the relationship between galaxy shapes and their local environments, without assuming an explicit IA form or relying on simulations. When applied to mock catalogs with realistic noisy IAs injected, it accurately reconstructs the noise-free, pure IA signal. Mapping these alignments provides a direct visualization of IA patterns in the mock catalogs. Combining DELTA with deep learning interpretation techniques provides further insights into the physics driving tidal relationships between galaxies. This new approach to understanding and controlling IAs is suitable for application to joint photometric and spectroscopic surveys such as the combination of upcoming Euclid, Rubin, and DESI datasets.

Binary systems in the Asymptotic Giant Branch (AGB) phase are widely recognized as a leading theoretical framework underpinning the observed asymmetric morphologies of planetary nebulae. However, the detection of binary companions in AGB systems is severely hampered by the overwhelming brightness and variability of the evolved primary star, which dominate the photo-metric and spectroscopic signatures. Ultraviolet (UV) excess emission has been proposed as a candidate diagnostic for the presence of binary companions in AGB systems. This paper evaluates the Chinese Space Station Telescope's (CSST) ability to detect UV excess emission in AGB stars, leveraging its unprecedented UV sensitivity and wide-field survey capabilities. We employed synthetic spectral libraries of M0-M8 type giants for primary stars and the ATLAS 9 atmospheric model grid for companion stars spanning a temperature range of 6500 K to 12000 K. By convolving these model spectra with the CSST multi-band filter system, we computed color-color diagrams (g-y versus NUV-u) to construct a diagnostic grid. This grid incorporates interstellar extinction corrections and establishes a framework for identifying AGB binary candidates through direct comparison between observed photometry and theoretical predictions. Furthermore, we discuss the physical origins of UV excess in AGB stars. This study pioneers a diagnostic framework leveraging CSST's unique multi-band UV-visible synergy to construct color-color grids for binary candidate identification, overcoming limitations of non-simultaneous multi-instrument observations.

We present a simulation of the time-domain catalog for the Nancy Grace Roman Space Telescope's High-Latitude Time-Domain Core Community Survey. This simulation, called the Hourglass simulation, uses the most up-to-date spectral energy distribution models and rate measurements for ten extra-galactic time-domain sources. We simulate these models through the design reference Roman Space Telescope survey: four filters per tier, a five day cadence, over two years, a wide tier of 19 deg$^2$ and a deep tier of 4.2 deg$^2$, with $\sim$20% of those areas also covered with prism observations. We find that a science-independent Roman time-domain catalog, assuming a S/N at max of >5, would have approximately 21,000 Type Ia supernovae, 40,000 core-collapse supernovae, around 70 superluminous supernovae, $\sim$35 tidal disruption events, 3 kilonovae, and possibly pair-instability supernovae. In total, Hourglass has over 64,000 transient objects, 11 million photometric observations, and 500,000 spectra. Additionally, Hourglass is a useful data set to train machine learning classification algorithms. We show that SCONE is able to photometrically classify Type Ia supernovae with high precision ($\sim$95%) to a z > 2. Finally, we present the first realistic simulations of non-Type Ia supernovae spectral-time series data from Roman's prism.

Most protoplanetary disks experience a phase in which they are subjected to strong ultraviolet radiation from nearby massive stars. This UV radiation can substantially alter their chemistry by producing numerous radicals and molecular ions. In this Letter we present detailed analysis of the JWST-NIRSpec spectrum of the d203-506 obtained as part of the PDRs4All Early Release Science program. Using state-of-the-art spectroscopic data, we searched for species using a multi-molecule fitting tool, PAHTATmol, that we developed for this purpose. Based on this analysis, we report the clear detection of ro-vibrational emission of the CH radical and likely detection of the H$_3^+$ molecular ion, with estimated abundances of a few times 10$^{-7}$ and approximately 10$^{-8}$, respectively. The presence of CH is predicted by gas-phase models and well explained by hydrocarbon photochemistry. H$_3^+$ is usually formed through reactions of H$_2$ with H$_2^+$ originating from cosmic ray ionization of H$_2$. However, recent theoretical studies suggest that H$_3^+$ also forms through UV-driven chemistry in strongly irradiated ($G_0>$10$^3$), dense ($n_{\rm H} >10^{6}$ cm$^{-3}$) gas. The latter is favored as an explanation for the presence of ``hot'' H$_3^+$ ($T_{\rm ex}\gtrsim$1000 K) in the outer disk layers of d203-506, coinciding with the emission of FUV-pumped H$_2$ and other ``PDR species'', such as CH$^+$, CH$_3^+$, and OH. Our detection of infrared emission from vibrationally excited H$_3^+$ and CH raises questions about their excitation mechanisms and, underscore that UV radiation can have a profound impact on the chemistry of planet forming disks. They also demonstrate the power of JWST pushing the limit for the detection of elusive species in protoplanetary disks.

The likely JWST detection of vibrationally excited H3+ emission in the irradiated disk d203-506, reported by Schroetter et al., raises the question of whether cosmic-ray ionization is enhanced in disks within clustered star-forming regions, or if alternative mechanisms contribute to H3+ formation and excitation. We present a detailed model of the photodissociation region (PDR) component of a protoplanetary disk-comprising the outer disk surface and the photoevaporative wind-exposed to strong external far-ultraviolet (FUV) radiation. We investigate key gas-phase reactions involving excited H2 that lead to the formation of H3+ in the PDR, including detailed state-to-state dynamical calculations of reactions H2 + HOC+ -> H3+ + CO and H2 + H+ -> H2+ + H. We also consider the effects of photoionization of vibrationally excited H2(v>=4), a process that has not previously been included in disk models. We find that these FUV-driven reactions dominate the formation of H3+ in the PDR of strongly irradiated disks, largely independently of cosmic-ray ionization. The predicted H3+ abundance peaks at x(H3+)~10^-8, coinciding with regions where HOC+ is also abundant. The high abundances of H3+ and HOC+ are ultimately linked to the strength of the external FUV field (G0), the presence of C+, and an enhanced reservoir of hot H2O. The predicted H3+ column densities (~10^13 cm^-2) are consistent with the presence of H3+ in the PDR of irradiated disks. We also find that formation pumping, resulting from exoergic reactions between excited H2 and HOC+, drive the vibrational excitation of H3+. We expect this photochemistry to be highly active in disks where G0 > 10^3. The H3+ formation pathways studied here may also be relevant in the inner disk region (near the host star), in exoplanetary ionospheres, and in the early Universe.

Multiple clumpy wind components ($v_{out}\sim0.2-0.3c$) in the luminous quasar PDS 456 have recently been resolved by XRISM in the Fe-K band for the first time. In this paper, we investigate the structure of ultra-fast outflows (UFOs) using coordinated observations from XRISM, XMM-Newton, and NuSTAR, along with the self-consistently calculated photoionization model \texttt{PION}. Our results reveal a stratified ionization structure likely driven by the radiation field, characterized by a relation between wind velocity and ionization parameter $v_{out}\propto\xi^{(0.38\pm0.06)}$. To evaluate the impact of the screening effect, we tested all possible order permutations of six \texttt{PION} components. We find that highly ionized UFOs ($\log\xi>4.5$) are insensitive to their relative positions, whereas the soft X-ray UFO ($\log\xi\sim3$ and $v_{out}\sim0.27c$) and the lowest-ionized hard X-ray UFO ($\log\xi\sim4.1$ and $v_ {out}\sim0.23c$) are statistically favored -- based on the evidence from both the C-statistic and Bayesian analysis -- to occupy the middle and innermost layers, respectively. This suggests a possible trend where slower UFOs are launched from regions closer to the supermassive black hole (SMBH). The soft X-ray UFO is found to be thermally unstable, regardless of its relative position. However, its location remains unclear. Our sequence analysis and its similarity to hard X-ray UFOs suggest that they may be co-spatial, while variability constraints support its location within the broad-line region at sub-parsec scales. Simulations with the gate-valve opened XRISM show that high-resolution soft X-ray data can enhance the reliability of our results. Furthermore, simulations with the future X-ray mission NewAthena demonstrate its capability to resolve the absorber sequence and spatial distributions, enabling the determination of UFO structures and their roles in AGN feedback.

Interesting data on Gamma Ray Burts (GRBs) and Cosmic Rays (CRs) have recently been made public. GRB221009A has a record ``peak energy". The CR electron spectrum has been measured to unprecedented high energies and exhibits a ``knee" akin to the ones in all-particle or individual-element CR nuclei. IceCube has not seen high-energy neutrinos associated with GRBs. AMS has published a CR positron spectrum conducive to much speculation. We examine these data in the light of the ``CannonBall Model" of GRBs and CRs, in which they are intimately related and which they do strongly validate.

Astrophysical observations provide compelling evidence for the existence of dark matter, a non-luminous component dominating the universe's mass-energy budget. Its gravitational influence is well-established on galactic scales; however, dark matter's precise nature and effect on spacetime geometry remain open questions. This study investigates modifications to the Schwarzschild metric due to the presence of dark matter, modeled as a perfect fluid with a specific equation of state. We derive an "exponential" metric incorporating this dark matter contribution and calculate its key characteristics: the event horizon, innermost stable circular orbit (ISCO), and photon sphere. Comparing these with Schwarzschild predictions reveals distinct deviations dependent on the dark matter distribution. Furthermore, we analyze the orbital velocity profiles derived from the exponential metric, demonstrating its potential to explain the observed flat rotation curves of galaxies. Our results underscore the importance of considering modified metrics in accurately describing spacetime near massive objects and provide a theoretical framework for further investigations into dark matter's role in galactic dynamics.

Though an anti-de Sitter (AdS) vacuum, corresponding to a negative cosmological constant (NCC), can be not responsible for the acceleration of current universe, it might coexist with one evolving positive dark energy component at low redshift, as well as with early dark energy around the recombination to solve the Hubble tension. In this paper, we investigate the scenario with one AdS vacuum around the recombination and one at low redshift, and from both current observational and theoretical perspectives preliminarily explore the possibility that the universe experienced a landscape with multiple AdS vacua since matter-radiation equality.

We propose a new UV-complete dark energy model which is \underbar{\it neither} a cosmological constant nor a slowly rolling scalar field. Our dark energy is the flux of a top form in a hidden sector gauge theory similar to QCD. The top form controls the vacuum energy generated by dark sector CP violation. Its flux discharges by the nucleation of membranes that source it. The tension and charge of the membranes are set by the chiral symmetry breaking scale $\sim 10^{-3} eV$, and the dark energy is a transient. It decays on the order of the current age of the universe. The decays decrease dark energy discretely and randomly, instead of gradually like rolling scalars. Since the decay rate is close to the present Hubble scale, $\Gamma \ga H_0^4$, in a time $\sim {\cal O}(1/H_0)$ the cosmic acceleration may even cease altogether.

Dark matter may freeze-out and undergo composite assembly while decoupled from the Standard Model. In this secluded composite scenario, while individual dark matter particles may be too weakly-coupled to detect, the assembled composite can potentially be detected since its effective coupling scales with number of constituents. We examine models and observables for secluded composites, and in particular we investigate the cosmological abundance of the composite binding field, which is generated during freeze-out annihilation and secluded composite assembly. This binding field could be discovered as a new relativistic species in the early universe or through later interactions as a subdominant dark component.

We present GollumFit, a framework designed for performing binned-likelihood analyses on neutrino telescope data. GollumFit incorporates model parameters common to any neutrino telescope and also model parameters specific to the IceCube Neutrino Observatory. We provide a high-level overview of its key features and how the code is organized. We then discuss the performance of the fitting in a typical analysis scenario, highlighting the ability to fit over tens of nuisance parameters. We present some examples showing how to use the package for likelihood minimization tasks. This framework uniquely incorporates the particular model parameters necessary for neutrino telescopes, and solves an associated likelihood problem in a time-efficient manner.

The Hamamatsu R12699-406-M2 is a $2\times2$ multi-anode 2-inch photomultiplier tube that offers a compact form factor, low intrinsic radioactivity, and high photocathode coverage. These characteristics make it a promising candidate for next-generation xenon-based direct detection dark matter experiments, such as XLZD and PandaX-xT. We present a detailed characterization of this photosensor operated in cold xenon environments, focusing on its single photoelectron response, dark count rate, light emission, and afterpulsing behavior. The device demonstrated a gain exceeding $2\cdot 10^6$ at the nominal voltage of -1.0 kV, along with a low dark count rate of $(0.4\pm0.2)\;\text{Hz/cm}^2$. Due to the compact design, afterpulses exhibited short delay times, resulting in some cases in an overlap with the light-induced signal. To evaluate its applicability in a realistic detector environment, two R12699-406-M2 units were deployed in a small-scale dual-phase xenon time projection chamber. The segmented $2\times2$ anode structure enabled lateral position reconstruction using a single photomultiplier tube, highlighting the potential of the sensor for effective event localization in future detectors.

In many extensions of the Standard Model electroweak phase transitions at high temperatures can be described in a minimal dimensionally reduced effective theory with SU(2) gauge field and fundamental Higgs scalar. In this effective theory, all thermodynamic information is governed by two dimensionless ratios $x \equiv \lambda_3/g^2_3$ and $y\equiv m^2_3/g^4_3$, where $\lambda_3$, $m^2_3$ and $g_3$ are the effective thermal scalar self-interaction coupling, the thermal mass and the effective gauge-coupling, respectively. By using non-perturbative lattice simulations to determine the rate of sphaleron transitions in the entire $(x,y)$-plane corresponding to the Higgs phase, and by applying previous lattice results for the bubble nucleation, we find a condition $x(T_c) \lesssim 0.025$ to guarantee preservation of the baryon asymmetry, which translates to $v/T_c \equiv \sqrt{2 \langle \phi^\dagger \phi \rangle}/T_c \gtrsim 1.33$ for the (gauge-invariant) Higgs condensate. This indicates that viability of the electroweak baryogenesis requires the phase transition to be slightly stronger than previously anticipated. Finally, we present a general template for analysing such viability in a wide class of beyond the Standard Model theories, in which new fields are heavy enough to be integrated out at high temperature.

The CYGNO experiment is developing a high-resolution gaseous Time Projection Chamber with optical readout for directional dark matter searches. The detector uses a helium-tetrafluoromethane (He:CF$_4$ 60:40) gas mixture at atmospheric pressure and a triple Gas Electron Multiplier amplification stage, coupled with a scientific camera for high-resolution 2D imaging and fast photomultipliers for time-resolved scintillation light detection. This setup enables 3D event reconstruction: photomultipliers signals provide depth information, while the camera delivers high-precision transverse resolution. In this work, we present a Bayesian Network-based algorithm designed to reconstruct the events using only the photomultipliers signals, yielding a full 3D description of the particle trajectories. The algorithm models the light collection process probabilistically and estimates spatial and intensity parameters on the Gas Electron Multiplier plane, where light emission occurs. It is implemented within the Bayesian Analysis Toolkit and uses Markov Chain Monte Carlo sampling for posterior inference. Validation using data from the CYGNO LIME prototype shows accurate reconstruction of localized and extended tracks. Results demonstrate that the Bayesian approach enables robust 3D description and, when combined with camera data, further improves the precision of track reconstruction. This methodology represents a significant step forward in directional dark matter detection, enhancing the identification of nuclear recoil tracks with high spatial resolution.

We present static axially symmetric fluid distributions not producing gravitational field outside their boundaries (i.e. fluid sources which match smoothly on the boundary surface to Minkowski space-time). These solutions provide further examples of ghost stars. A specific model is fully described, and its physical and geometrical properties are analyzed in detail. This includes the multipole moment structure of the source and its complexity factors, both of which vanish for our solution.

Gravitational-wave astronomy has entered a regime where it can extract information about the population properties of the observed binary black holes. The steep increase in the number of detections will offer deeper insights, but it will also significantly raise the computational cost of testing multiple models. To address this challenge, we propose a procedure that first performs a non-parametric (data-driven) reconstruction of the underlying distribution, and then remaps these results onto a posterior for the parameters of a parametric (informed) model. The computational cost is primarily absorbed by the initial non-parametric step, while the remapping procedure is both significantly easier to perform and computationally cheaper. In addition to yielding the posterior distribution of the model parameters, this method also provides a measure of the model's goodness-of-fit, opening for a new quantitative comparison across models.

These notes are based on a sequence of 4 lectures delivered at the 2024 Theoretical Advanced Study Institute (TASI) and at the Università degli Studi di Padova. They are intended for graduate students at the early stages of their study of dark matter with some prior exposure to cosmology and quantum field theory. The primary aim is to offer an accessible introduction to dark matter and to lay the groundwork for exploring its phenomenology. These lectures are not intended to serve as a comprehensive review. We begin by motivating the study of dark matter through a discussion of the empirical evidence and the constraints it places on dark matter properties. This is followed by an overview of several canonical mechanisms for the production of cosmological dark matter, and a concluding section that surveys current experimental and observational efforts to detect it with a focus on direct detection.