Locally authored papers of the past 5 days

The point-spread function of the integral-field unit (IFU) mode of the JWST's NIRSpec is heavily under-sampled, creating resampling noise seen as low-frequency sinusoidal-like artifacts, or "wiggles". These artifacts in the data are not corrected in the JWST data pipeline, and significantly impact the science that can be achieved at a single-pixel level. We present WICKED (WIggle Corrector Kit for NIRSpEc Data), a tool designed to empirically remove wiggles. WICKED uses the Fast Fourier Transform to identify wiggle-affected spaxels across the data cube. Spectra are modeled with a mix of integrated aperture and annular templates, a power-law, and a second-degree polynomial. The method works across all medium- and high-resolution NIRSpec gratings: F070LP, F100LP, F170LP, and F290LP. WICKED can recover the true overall spectral shape up to a factor of 3.5x better compared to uncorrected spectra. It recovers the equivalent width of absorption lines within 5% of the true value-~3x better than uncorrected spectra and ~2x better than other methods. WICKED significantly improves kinematic measurements, recovering the line-of-sight velocity (LOSV) within 1% of the true value -- more than 100x better than uncorrected spectra at S/N ~40. As a case study, we applied WICKED to G235H/F170LP IFU data of the elliptical galaxy NGC5128, finding good agreement with previous studies. In wiggle-affected regions, the uncorrected spectrum showed stellar LOSV and velocity dispersion differences compared to the WICKED-cleaned spectrum, of ~17x and ~36x larger than the estimated uncertainties, respectively. Wiggles in NIRSpec IFU data can introduce severe biases in spectral shape, line measurements, and kinematics to values larger than the typical uncertainties. WICKED provides a robust, user-friendly solution, enabling precise single-pixel studies and maximizing JWST's potential.

This study provides a detailed analysis of fourteen distant interplanetary shocks observed by the Solar Wind Around Pluto (SWAP) instrument onboard New Horizons. These shocks were observed with a pickup ion data cadence of approximately 30 minutes, covering a heliocentric distance range of ~52-60 au. All the shocks observed within this distance range are fast-forward shocks, and the shock compression ratios vary between ~1.2 and 1.9. The shock transition scales are generally narrow, and the SW density compressions are more pronounced compared to the previous study of seven shocks by McComas et al. (2022). A majority (64%) of these shocks have upstream sonic Mach numbers greater than one. In addition, all high-resolution measurements of distant interplanetary shocks analyzed here show that the shock transition scale is independent of the shock compression ratio. However, the shock transition scale is strongly anti-correlated with the shock speed in the upstream plasma frame, meaning that faster shocks generally yield sharper transitions.

Observations of GeV gamma-ray emission from the well-studied mixed-morphology supernova remnant (SNR) W44 by Fermi-LAT and AGILE imply that it is a site of significant cosmic ray acceleration. The spectral energy distribution (SED) derived from the GeV data suggest that the gamma-ray emission likely originates from the decay of neutral pions generated by cosmic-ray interactions. It is essential to measure the SED of W44 in the X-ray and very high energy (VHE) gamma-ray bands to verify the hadronic origin of the emission and to gauge the potential contributions from leptonic emission. We report an upper-limit of the nonthermal X-ray flux from W44 of 5 $\times$ 10$^{-13}$ erg cm$^{-2}$ s$^{-1}$ in the 0.5 - 8.0 keV band based on $\sim$ 300 ks of XMM-Newton observations. The X-ray upper limit is consistent with previously estimated hadronic models, but in tension with the leptonic models. We estimate the VHE flux upper limit of $\sim$ 1.2 $\times$ 10$^{-12}$ erg s$^{-1}$ cm$^{-2}$ in the 0.5 - 5.0 TeV range from W44 using data from the Very Energetic Radiation Imaging Telescope Array System (VERITAS). Our non-detection of W44 at VHE wavlengths is in agreemnent with observations from other imaging atmospheric Cherenkov telescopes (IACTs) and is perhaps consistent with the evolutionary stage of the SNR.

The Hubble tension has emerged as a critical crisis in cosmology, with the cause remaining unclear. Determining the Hubble constant ($H_0$) independently of cosmological models and distance ladders will help resolve this crisis. In this letter, we for the first time use 47 gravitational-wave (GW) standard sirens from the third Gravitational-Wave Transient Catalog to calibrate distances in the strong lensing system, RXJ1131-1231, and constrain $H_0$ through the distance-sum rule, with minimal cosmological assumptions. We assume that light propagation over long distances is described by the Friedmann-Lemaitre-Robertson-Walker metric and that geometrical optics holds, but we do not need to assume the universe's contents or the theory of gravity on cosmological scales. Fixing $\Omega_K=0$, we obtain $H_0=73.22^{+5.95}_{-5.43}$ ${\rm km}~{\rm s}^{-1}~{\rm Mpc}^{-1}$ and $H_0=70.40^{+8.03}_{-5.60}$ ${\rm km}~{\rm s}^{-1}~{\rm Mpc}^{-1}$ by using the deflector galaxy's mass model and kinematic measurements to break mass-sheet transform, respectively. When $\Omega_K$ is not fixed, the central value of $H_0$ increases further. We find that our results are still dominated by statistical errors, and at the same time, we notice the great potential of using GW dark sirens to provide calibration, owing to their higher redshifts. When using 42 binary black holes and RXJ1131-1231, we obtain a $8.46 \%$ $H_0$ constraint precision, which is better than that from the bright siren GW170817 using the Hubble law by about $40\%$. In the future, as the redshift range of GW dark sirens increases, more and more SGLTDs can be included, and we can achieve high-precision, model-independent measurements of $H_0$ without the need for GW bright sirens.

Sterile neutrinos can influence the evolution of the universe, and thus cosmological observations can be used to search for sterile neutrinos. In this study, we utilized the latest baryon acoustic oscillations data from DESI, combined with the cosmic microwave background data from Planck and the five-year supernova data from DES, to constrain the interacting dark energy (IDE) models involving both cases of massless and massive sterile neutrinos. We consider four typical forms of the interaction term $Q=\beta H \rho_{\rm de}$, $Q=\beta H \rho_{\rm c}$, $Q=\beta H_{0} \rho_{\rm de}$, and $Q=\beta H_{0} \rho_{\rm c}$, respectively. Our analysis indicates that the current data provide only a hint of the existence of massless sterile neutrinos (as dark radiation) at about the $1\sigma$ level. In contrast, no evidence supports the existence of massive sterile neutrinos. Furthermore, in IDE models, the inclusion of (massless/massive) sterile neutrinos has a negligible impact on the constraint of the coupling parameter $\beta$. The IDE model of $Q=\beta H \rho_{\rm c}$ with sterile neutrinos does not favor an interaction. However, the other three IDE models with sterile neutrinos support an interaction in which dark energy decays into dark matter.

This study presents a novel method using spin quantum sensors to explore temporal variations of fundamental constants, significantly expanding the frequency range and providing constraints on scalar dark matter.

Cosmic rays are deemed to be generated by a process known as ``Fermi acceleration", in which charged particles scatter against magnetic fluctuations in astrophysical plasmas. The process itself is however universal, has both classical and quantum formulations, and is at the basis of dynamical systems with interesting mathematical properties, such as the celebrated Fermi-Ulam model. Despite its effectiveness in accelerating particles, Fermi acceleration has so far eluded unambiguous verifications in laboratory settings. Here, we realize the first fully controllable Fermi accelerator by colliding ultracold atoms against engineered movable potential barriers. We demonstrate that our Fermi accelerator, which is only 100 um in size, can produce ultracold atomic jets with velocities above half a meter per second. Adding dissipation, we also experimentally test Bell's general argument for the ensuing energy spectra, which is at the basis of any model of cosmic ray acceleration. On the one hand, our work effectively opens the window to the study of high energy astrophysics with cold atoms, offering new capabilities for the understanding of phenomena such as diffusive acceleration at collisionless shocks. On the other, the performance of our Fermi accelerator is competitive with those of best-in-class accelerating methods used in quantum technology and quantum colliders, but with substantially simpler implementation and virtually no upper limit.

We aim to study the polarization and magnetic field properties of the SNR HB 9 using new 21-cm continuum cube data from the Five-hundred-meter Aperture Spherical radio telescope (FAST). We computed the Faraday depth at 21 cm, and re-analyzed the rotation measures (RMs) of HB 9 using in addition Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data. FAST total-intensity images of two subbands are decomposed into components of multiple angular scales to check spectral-index variation via temperature versus temperature plots (TT-plots). The filamentary emission has a spectral index ($S\sim\nu^{\alpha}$) of $\alpha=-$0.52, corresponding to freshly accelerated relativistic electrons. The diffuse emission has a steeper spectrum of $\alpha=-$0.63, corresponding to confined electrons that are no longer accelerated. The FAST detected 1385-MHz polarized emission might come from a thin layer in the outer envelope of the shells, with a Faraday depth of 4-28 rad m$^{-2}$ from the Faraday rotation synthesis result. The RMs derived from the Effelsberg 2695-MHz and Urumqi 4800-MHz polarization data show about 70 rad m$^{-2}$ in the eastern and northern shell, and 124 rad m$^{-2}$ in the inner and southern patches. The regular magnetic field is about 5$-$8 $\mu$G over the remnant. The northern shell shows depolarization at 2695 MHz relative to the 4800-MHz polarization data, indicating an additional random magnetic field of 12 $\mu$G on the scale of 0.6 pc. The shock wave might have entered the dense gas environment in the northern-shell region and has driven turbulence to cause depolarization at 2695 MHz.

The main contributors of the IceCube diffuse neutrino flux remain unclear. Tidal disruption events (TDEs) have been proposed as potential emitters of the high-energy neutrinos detected by IceCube. Therefore, investigating the correlation between the TDE population and IceCube neutrinos could help us better understand whether the TDE population could be potential high-energy neutrino emitters. In this paper, we perform a systematic search for TDEs that are associated with neutrinos in a sample including 143 IceCube neutrino alert events and 61 TDEs classified by the Zwicky Transient Facility (ZTF) - Bright Transient Survey (BTS). Furthermore, considering that the TDEs/TDE candidates reported as potential IceCube neutrino emitters are all accompanied by infrared (IR) observations, we further select the TDEs with IR observations from these 61 TDEs as a subsample to examine the correlation with neutrinos. Based on the Wide-field Infrared Survey Explorer (WISE) mission database, seven TDEs are identified as having IR observations. Due to good spatial localization is crucial for association analysis, we employ two methods to handle alert events with large error radii in our sample. Then we employ three Monte Carlo simulation methods to investigate the correlation between TDE sample/subsample and IceCube neutrinos. Finally, after considering spatial and temporal criteria, seven TDEs with IR flares show the most significant correlation at a 2.43{\sigma} confidence level. If we tentatively further take the time delay factor into account in the weighting scheme, the correlation enhances to 2.54{\sigma} confidence level.

Magnetic accreting white dwarfs in cataclysmic variables have been known to show bursts driven by different physical mechanisms; however, the burst occurrence is much rarer than in their non-magnetic counterparts. DW Cnc is a well-studied intermediate polar that showed a burst with a 4-magnitude amplitude in 2007. Here we report on a recent burst in DW Cnc observed by ASAS-SN that reached a peak luminosity of 6.6 $\times$ 10$^{33}$ erg~s$^{-1}$, another 4 mag increase from its quiescent high state level. The released energy of the burst suggests that these are micronovae, a distinctive type of burst seen in magnetic systems that may be caused by a thermonuclear runaway in the confined accretion flow. Only a handful of systems, most of them intermediate polars, have a reported micronova bursts. We also report on the reappearance of the negative superhump of DW~Cnc as shown by TESS and OPTICAM data after the system emerges from its low state and immediately before the burst. We further report on a new phenomenon, where the spin signal turns "on" and "off" on the precession period associated with the negative superhump, which may indicate pole flipping. The new classification of DW Cnc as a micronova as well as the spin variability show the importance of both monitoring known micronova systems and systematic searches for more similar bursts, to limit reliance on serendipitous discoveries.

This paper investigates the potential of intensity interferometry, based on the Hanbury Brown-Twiss effect, for measuring supernova sizes and distances. Through optimized telescope positioning, observing strategy, and advancements in single-photon detection technology, this method can provide precise angular size measurements of Type Ia supernovae as bright as 12~mag, corresponding to a local volume out to $z\sim0.004$, with an anticipated rate of $\sim 1$ events per year. The combination of angular size data with known physical dimensions enables accurate distance determination. Multiple telescope pairs at different relative positions allow tomographic mapping of the ejecta structure while reducing distance uncertainties. As Type Ia supernovae serve as standardizable candles for measuring the Universe's expansion history, combining intensity interferometry distances with the supernova Hubble diagram facilitates measurements of the Hubble constant $H_0$.

We present spatially-resolved spectroscopic observations of 10 isolated Galactic HII regions using data from the LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (LAMOST MRS-N). The high spatial resolution of the data allows us to investigate the 1D radial profiles of emission line fluxes (Ha, [S II] and [N II]), flux ratios ([N II]/Ha, [S II]/Ha and [S II]/[N II]), and radial velocities of these three emission lines. Among these regions, two are ionization-bounded, while the remaining eight are matter-bounded. The matter-bounded HII regions exhibit shallower slopes in their radial flux profiles compared to the ionization-bounded ones. In most cases, the [N II]/Ha and [S II]/Ha ratios increase with distance from the center of the HII regions, consistent with model predictions that low-ionization emissions dominate the outer zones of these regions. The two ionization-bounded HII regions have kinematic ages (t) of 0.2 and 0.3 Myr, while the matter-bounded regions span ages from 1 to 12 Myr. For the matter-bounded HII regions, the optical emission flux decreases continuously beyond the photodissociation region (PDR), extending to approximately 1-4 times the radius of the PDR (r_PDR). The escape fraction f_esc of ionizing photons, derived from 1D Ha radial flux profiles, is ~ 0% for ionization-bounded HII regions, while it ranges from 50% to 90% for the matter-bounded HII regions. The correlation between f_esc and t suggests that evolved HII regions (with t > 1 Myr) contribute more significantly to ionizing the surrounding diffuse ionized gas compared to younger, newly formed HII regions.

We analyze the emission and absorption lines during photospheric radius expansion (PRE) X-ray bursts from the ultracompact binary 4U 1820--30, observed with the Neutron Star Interior Composition Explorer (NICER). Using Monte Carlo simulations to estimate the significance, we identified a 1 keV emission line from 14 bursts, a 3 keV absorption line from 12 bursts, and 1.6 keV absorption from one burst. By coadding the burst spectra at the maximum radius phase, we detected a 1.034 keV emission line with significance of $14.2\sigma$, and absorption lines at 1.64 and 3 keV with significances of $10.8\sigma$ and $11.7\sigma$, respectively. The observed energy shifts are consistent with the prediction from the burst-driven wind model, indicating that all three spectral features are produced by the PRE wind. Analysis of the ratios between the emission and absorption line energies suggests that the 1 keV feature is a superposition of several narrower Fe L-shell lines. To evaluate the scientific capabilities of the Hot Universe Baryon Surveyor (HUBS), we simulated mock observations of multiple narrow lines near 1 keV. The results demonstrate that HUBS is well suited for detailed studies of the 1 keV emission line during bursts, offering significant potential to advance our understanding of these phenomena.

In this study, we unveil a new AI model, termed PhyE2E, to discover physical formulas through symbolic regression. PhyE2E simplifies symbolic regression by decomposing it into sub-problems using the second-order derivatives of an oracle neural network, and employs a transformer model to translate data into symbolic formulas in an end-to-end manner. The resulting formulas are refined through Monte-Carlo Tree Search and Genetic Programming. We leverage a large language model to synthesize extensive symbolic expressions resembling real physics, and train the model to recover these formulas directly from data. A comprehensive evaluation reveals that PhyE2E outperforms existing state-of-the-art approaches, delivering superior symbolic accuracy, precision in data fitting, and consistency in physical units. We deployed PhyE2E to five applications in space physics, including the prediction of sunspot numbers, solar rotational angular velocity, emission line contribution functions, near-Earth plasma pressure, and lunar-tide plasma signals. The physical formulas generated by AI demonstrate a high degree of accuracy in fitting the experimental data from satellites and astronomical telescopes. We have successfully upgraded the formula proposed by NASA in 1993 regarding solar activity, and for the first time, provided the explanations for the long cycle of solar activity in an explicit form. We also found that the decay of near-Earth plasma pressure is proportional to r^2 to Earth, where subsequent mathematical derivations are consistent with satellite data from another independent study. Moreover, we found physical formulas that can describe the relationships between emission lines in the extreme ultraviolet spectrum of the Sun, temperatures, electron densities, and magnetic fields. The formula obtained is consistent with the properties that physicists had previously hypothesized it should possess.

Only one globular cluster (GC), 47 Tuc, has been found to contain intracluster medium, with an electron density 100 times higher than that of the ISM in its vicinity. The characteristics of this intracluster medium are closely related to GC evolution and the compact objects within. However, significant knowledge gaps remain regarding the ionized gas content of GCs, particularly in Galactic halo clusters. We carried out a polarization census of GC pulsars using MeerKAT and FAST. This first combined effort of observations from these two major radio telescopes resulted in high signal-to-noise ratio, full polarization pulse profiles for 43 pulsars in 8 GCs, doubling the number of rotation measures (RMs) known in these clusters. The accuracy of dispersion measures (DMs) was improved by a factor of 8 compared to previous publications. No intracluster medium was found, and at least two halo GCs showed more stringent upper limits on electron density than that detected in 47 Tuc. The surprising barrenness of GCs suggests effective gas removal mechanisms, such as strong winds from millisecond pulsars and/or ionizing radiation from post-AGB stars and young white dwarfs.

We study the black hole mass $-$ host galaxy stellar mass relation, $M_{\rm{BH}}-M_{\ast}$, for a sample of 706 $z \lesssim 1.5$ and $i \lesssim 24$ optically-variable active galactic nuclei (AGNs) in three Dark Energy Survey (DES) deep fields: C3, X3, E2, which partially cover Chandra Deep Field-South, XMM Large Scale Structure survey, and European Large Area ISO Survey, respectively. The parent sample was identified by optical variability from the DES supernova survey program imaging. Using publicly available spectra and photometric catalogs, we consolidate their spectroscopic redshifts, estimate their black hole masses using broad line widths and luminosities, and obtain improved stellar masses using spectral energy distribution fitting from X-ray to mid-infrared wavelengths. Our results confirm previous work from Hyper-Suprime Camera imaging that variability searches with deep, high-precision photometry can reliably identify AGNs in low-mass galaxies up to $z\sim1$. However, we find that the hosted black holes are overmassive than predicted by the local AGN relation, fixing host galaxy stellar mass. Instead, $z\sim 0.1-1.5$ variability-selected AGNs lie in between the $M_{\rm{BH}}-M_{\ast}$ relation for local inactive early-type galaxies and local active galaxies. This result agrees with most previous studies of $M_{\rm{BH}}-M_{\ast}$ relation for AGNs at similar redshifts, regardless of selection technique. We demonstrate that studies of variability selected AGN provide critical insights into the low-mass end of the $M_{\rm{BH}}-M_{\ast}$ relation, shedding light on the occupation fraction of that provides constraints on early BH seeding mechanisms and self-regulated feedback processes during their growth and co-evolution with their hosts.

Intracluster light (ICL) provides a record of the dynamical interactions undergone by clusters, giving clues on cluster formation and evolution. Here, we analyse the properties of ICL in the massive cluster Abell 2390 at redshift z=0.228. Our analysis is based on the deep images obtained by the Euclid mission as part of the Early Release Observations in the near-infrared (Y, J, H bands), using the NISP instrument in a 0.75 deg$^2$ field. We subtracted a point--spread function (PSF) model and removed the Galactic cirrus contribution in each band after modelling it with the DAWIS software. We then applied three methods to detect, characterise, and model the ICL and the brightest cluster galaxy (BCG): the CICLE 2D multi-galaxy fitting; the DAWIS wavelet-based multiscale software; and a mask-based 1D profile fitting. We detect ICL out to 600 kpc. The ICL fractions derived by our three methods range between 18% and 36% (average of 24%), while the BCG+ICL fractions are between 21% and 41% (average of 29%), depending on the band and method. A galaxy density map based on 219 selected cluster members shows a strong cluster substructure to the south-east and a smaller feature to the north-west. Based on colours, the ICL (out to about 400 kpc) seems to be built by the accretion of small systems (M ~ $10^{9.5}$ solar mass), or from stars coming from the outskirts of Milky Way-type galaxies (M ~ $10^{10}$ solar mass). Though Abell 2390 does not seem to be undergoing a merger, it is not yet fully relaxed, since it has accreted two groups that have not fully merged with the cluster core. We estimate that the contributions to the inner 300 kpc of the ICL of the north-west and south-east subgroups are 21% and 9% respectively.

In this paper, we examine the neutrino signals from 24 initially non-rotating, three-dimensional core-collapse supernova (CCSN) simulations carried to late times. We find that not only does the neutrino luminosity signal encode information about each stage of the CCSN process, but that the monotonic dependence of the luminosity peak height with compactness enables one to infer the progenitor core structure from the neutrino signal. We highlight a systematic relationship between the luminosity peak height with its timing. Additionally, we emphasize that the total energy radiated in neutrinos is monotonic with progenitor compactness, and that the mean neutrino energy contains a unique spiral SASI signature for nonexploding, BH-forming models. We also find that neutrino emissions are not isotropic and that the anisotropy increases roughly with progenitor compactness. To assess the detectability of these neutrino signal features, we provide examples of the event rates for our models for the JUNO, DUNE, SK, and IceCube detectors using the SNEWPY software, and find that many of the trends in the luminosity signal can be detectable across several detectors and oscillation models. Finally, we discuss correlations between the radiated neutrino energy and the evolution of the gravitational-wave f-mode.

The splashback radius $R_{\rm sp}$ is a boundary of a halo that separates infalling and accreted matter. This results in a steep drop in the density profile at $R_{\rm st}$, which is a commonly adopted proxy for $R_{\rm sp}$. Observationally, $R_{\rm st}$ can be measured through fitting the projected galaxy number density profile of the halo, but there has been some discrepancy between the observed and expected $R_{\rm st}$. Therefore, we investigate whether the projection of the density profile onto the plane of the sky could lead to any systematic bias in determining $R_{\rm st}$, by studying the true 3-dimensional and projected halo density profiles from the IllustrisTNG simulation. We investigate a range of projection lengths, and find that $R^p_{\rm st}$ obtained from projected profiles is close to the true $R^*_{\rm st}$, but has a slight decreasing trend with increasing projection length. We also quantify the prominence of the splashback feature and find how the feature shape changes with projection length.

Merging our supernova code F{\sc{ornax}} with the Box3D fast-flavor neutrino oscillation formalism, we explore the effects of fast-flavor conversion (FFC) in state-of-the-art 1D and 2D core-collapse supernova simulations. We find that after a few tens of milliseconds after bounce the FFC emerges just interior to and exterior to the stalled shock wave. It does not obtain in the PNS core nor near the average neutrinosphere radii. Interior to the shock, this results in a temporary change in the net neutrino heating rate of $\sim$10\%, due mostly to a hardening of the $\nu_e$ and $\bar{\nu}_e$ neutrino spectra, despite the decrease in their corresponding neutrino number fluxes. In 1D, the hydrodynamic effects are not large, with increases in the stalled shock radius by of order ten to twenty kilometers that abate within a few hundred milliseconds. In 2D, the hydrodynamic effect of the FFC is a bit more noticeable, resulting in slightly earlier explosions for models for lower-mass progenitors, but also potentially inhibiting explosions for some higher-mass progenitors. Fast-flavor conversion continues to operate at larger radii at later times. The net result is a shift upward in the $\nu_{\mu}$ energy and number luminosities and a shift downward in the same quantities for both the $\nu_e$ and $\bar{\nu}_e$ neutrinos. There seems to be a trend at very large radii and later times towards partial species and spectral equipartition. If this is true, it could be an interesting feature of supernova neutrino detection at later times in underground and under-ice facilities.

Individual stars located near the caustics of galaxy clusters can undergo extreme magnification when crossing micro-caustics, rendering them observable even at cosmological distances. Though most massive stars are likely reside in binary systems rather than as single star, the influence of binary star system on magnification events is severely under-explored. In this work, we simulate the light curves produced by detached binary stars crossing micro-caustics, aiming to characterize their unique observational this http URL high-resolution magnification maps generated by the GPU-PMO-CAUSTIC algorithm and PARSEC stellar models with red-shifted magnitude, we examined the impact of binary star parameters and crossing geometries on microlensing magnification patterns. Our simulations reveal that binary stars produce diverse light curve features, including overlapping peaks, plateau-like structures, and time-variable color-magnitude differences. These features, particularly the distinct temporal variations in spectral energy distributions, offer diagnostic tools for distinguishing binary systems from single this http URL further demonstrate the potential of multi-band photometry using the Chinese Space Station Telescope's Multi-Channel Imager (CSST-MCI) to capture these this http URL findings provide theoretical support for identifying binary systems in future caustic-crossing events, enabling more accurate characterization of high-redshift stellar populations.

As the intermediate-mass siblings of stars and planets, brown dwarfs (BDs) are vital to study for a better understanding of how objects change across the planet-to-star mass range. Here, we report two low-mass transiting BD systems discovered by TESS, TOI-4776 (TIC 196286578) and TOI-5422 (TIC 80611440), located in an under-populated region of the BD mass-period space. These two systems have comparable masses but different ages. The younger and larger BD is TOI-4776b with $32.0^{+1.9}_{-1.8}M_{Jup}$ and $1.018^{+0.048}_{-0.043}R_{Jup}$, orbiting a late-F star about $5.4^{+2.8}_{-2.2}$ Gyr old in a 10.4138$\pm$0.000014 day period. The older TOI-5422b has $27.7^{+1.4}_{-1.1}M_{Jup}$ and $0.815^{+0.031}_{-0.026}R_{Jup}$ in a 5.3772$\pm$0.00001 day orbit around a subgiant star about $8.2\pm2.4$ Gyr old. Compared with substellar mass-radius (M-R) evolution models, TOI-4776b has an inflated radii. In contrast, TOI-5422b is slightly "underluminous" with respect to model predictions, which is not commonly seen in the BD population. In addition, TOI-5422 shows apparent photometric modulations with a rotation period of 10.75$\pm$0.54 day found by rotation analysis, and the stellar inclination angle is obtained to be $I_{\star}=75.52^{+9.96}_{-11.79}$$^{\circ}$. Therefore, it is likely that TOI-5422b is spinning up the host star and its orbit is aligned with the stellar spin axis.

We present 12 observations of the accreting millisecond X-ray pulsar Aql X-1, taken from August 2022 to October 2023 using the Five-hundred-meter Aperture Spherical Radio Telescope at 1250 MHz. These observations covered both the quiescence and X-ray outburst states, as determined by analyzing the X-ray data from the Neutron Star Interior Composition Explorer and the Monitor of All-sky X-ray Image. Periodicity and single-pulse searches were conducted for each observation, but no pulsed signals were detected. The obtained upper limit flux densities are in the range of 2.86-5.73 uJy, which provide the lowest limits to date. We discuss several mechanisms that may prevent detection, suggesting that Aql X-1 may be in the radio-ejection state during quiescence, where the radio pulsed emissions are absorbed by the matter surrounding the system.