Papers for Monday, Apr 21 2025

I highlight that there is a substantial number of papers (at least 11 published since 2024) which all refer to a specific type of plot as an "Allan variance" plot, when in fact they seem to be plotting the standard deviation of the residuals versus bin size. The Allan variance quantifies the stability of a time series by calculating the average squared difference between successive time-averaged segments over a specified interval; it is not equivalent to the standard deviation. This misattribution seems particularly prolific in the exoplanet transit spectroscopy community. However, I emphasize that it does not impact the scientific analyses presented in those works. I discuss where this confusion seems to stem from and encourage the community to ensure statistical measures are named correctly to avoid confusion.

There is growing evidence that planet formation begins early, within the $\lesssim 1$Myr Class 0/I phase, when infall dominates disk dynamics. Our goal is to determine if Class 0/I disks reach the conditions needed to form planetesimals ($\sim 100$km planet building blocks) by the streaming instability (SI). We focus on a recent suggestion that early infall causes an ``inflationary'' phase in which dust grains are advected outward. We modified the \texttt{DustPy} code to build a 1D disk that includes dust evolution, infall, and heating and cooling sources. We ran six models and examined the implications for the SI, taking into account recent works on how the SI responds to external turbulence. In line with other works, we find that grains are advected outward, which leads to ``advection-condensation-drift'' loop that greatly enhances the dust density at the water snowline. However, we do not see this process at the silicate line. Instead, we find a new pile up at the edge of the expanding disk. However, despite these localized enhancements, even a modest amount of turbulence ($\alpha = 10^{-3}$) leaves planetesimal formation far out of reach. The midplane dust-to-gas ratio is at least an order of magnitude below the SI threshold, even taking into account recent results on how dust coagulation boosts the SI. For planetesimals to form in the Class 0/I phase may require a way to transport angular momentum without turbulence (e.g., disk winds) or a non-SI mechanism to form planetesimals.

The rates and properties of tidal disruption events (TDEs) provide valuable insights into their host galaxy central stellar densities and the demographics of their central supermassive black holes (SMBHs). TDEs have been observed only at low redshifts ($z \lesssim 1$), due to the difficulty in conducting deep time-domain surveys. In this work, we present the discovery of a high-redshift TDE candidate, HZTDE-1, in the COSMOS-Web survey with JWST's NIRCam, using a novel selection technique based on color and morphology. We first outline a methodology for identifying high-z TDEs in deep infrared imaging surveys, leveraging their unique spectral energy distributions (SEDs) and morphologies of these transients. We apply this technique to COSMOS-Web in filters F115W, F150W, F277W, and F444W, and identify HZTDE-1, a transient point source relative to archival UltraVISTA infrared observations. If we assume it is a TDE, we estimate its photometric redshift to be $z=5.02^{+1.32}_{-1.11}$. HZTDE-1 cannot be explained by reasonable supernova or AGN models. However, we cannot rule out a superluminous supernova at $z\gtrsim3$. If confirmed with follow-up observations, HZTDE-1 would represent the highest-redshift TDE discovery to date, and would suggest an enhancement of the TDE rate in the high-redshift universe. Our method, which can be applied to future deep surveys with JWST and Roman, offers a pathway to identify TDEs at $z>4$ and probe black hole demographics at early cosmic times.

Scalar fields are ubiquitous in theories of high-energy physics. In the context of cosmic inflation, this suggests the existence of spectator fields, which provide a subdominant source of energy density. We show that spectator fields boost the inflationary production of primordial black holes, with single-field ultra-slow roll evolution supplanted by a phase of evolution along the spectator direction, and primordial perturbations amplified by the resulting multifield dynamics. This generic mechanism is largely free from the severe fine-tuning that afflicts single-field inflationary PBH models.

We present measurements of $z \sim 2.4$ ultraviolet background light using Lya absorption from galaxies at $z \sim 2-3$ in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) database. Thanks to the wide area of this survey, we also measure the variability of this light across the sky. The data suggest an asymmetric geometry where integrated ultraviolet light from background galaxies is absorbed by \ion{H}{1} within the halo of a foreground galaxy, in a configuration similar to damped Lya systems. Using stacking analyses of over 400,000 HETDEX LAE spectra, we argue that this background absorption is detectable in our data. We also argue that the absorption signal becomes negative due to HETDEX's sky subtraction procedure. The amount that the absorption is over-subtracted is representative of the $z \sim 2.4$ UV contribution to the overall extragalactic background light (EBL) at Lya. Using this method, we determine an average intensity (in $\nu J_{\nu}$ units) of $12.9 \pm 3.7$ nW m$^{-2}$ sr$^{-1}$ at a median observed wavelength of 4134 angstroms, or a rest-frame UV background intensity of $508 \pm 145$ nW m$^{-2}$ sr$^{-1}$ at $z\sim2.4$. We find that this flux varies significantly depending on the density of galaxies in the field of observation. Our estimates are consistent with direct measurements of the overall EBL.

The epoch of reionisation is a key phase in the cosmic history, characterised by the ionisation of the intergalactic medium by the first luminous sources. In this work, we constrain the reionisation history of the Universe using data from the cosmic microwave background, more specifically the latest Planck dataset (Public Data Release 4, PR4). We investigate a wide range of reionisation models, from simple parametric descriptions to more flexible non-parametric approaches, systematically evaluating their impact on the inferred constraints. Special attention is given to implicit priors introduced by each model and their influence on the derived reionisation optical depth $\tau$. To achieve this, we employ both Bayesian and frequentist methods to derive robust constraints. We obtain consistent estimates of $\tau$ across models, highlighting the robustness of the constraints on the integrated optical depth derived from Planck PR4 data. The posterior mean averaged across models is $\tau = 0.0576 \pm 0.0060$, while the average best-fit value, $\tau = 0.0581$, reflects the presence of small volume effects. Based on our analysis, we estimate that an additional uncertainty, associated with the modelling of reionisation, contributes an error of approximately $\sigma_\tau\!\sim\!0.0006$. Beyond the integrated optical depth, our analysis reveals that the inferred ionisation fraction as a function of redshift is highly model-dependent. While current CMB data do not favour significant early ionisation, they are consistent with a modest contribution from ionised gas at very early times ($z>15$). Although indicative upper bounds can be placed on such contributions, these limits remain strongly dependent on the assumed model.

The Transiting Exoplanet Survey Satellite (TESS) has provided stellar rotation periods across much of the sky through high-precision light curves, but the reliability and completeness of these measurements require careful evaluation. We assess the accuracy of TESS-derived rotation periods by leveraging a cross-matched sample of ~23,000 stars observed by both TESS and the K2 mission, treating K2 periods as a benchmark. Using causal pixel models to extract light curves and the Lomb-Scargle (LS) periodogram to identify rotation signals, we quantify the empirical uncertainties, reliability, and completeness of TESS rotation period measurements. We find that uncertainties on TESS-derived rotation periods are typically below 3% for stars with periods < 10 days. Rotation periods are generally reliable out to 10 days, with >80% of measurements matching the K2 benchmark. Completeness and reliability drop dramatically for periods beyond ~12 days due to the 27-day sector limitation. Stricter cuts on TESS magnitude and LS power improve reliability; the highest LS power tested (>0.2) ensures >90% reliability below 10 days but removes over half of potential detections. Stitching consecutive-sector light curves reduces period uncertainties but does not improve overall reliability or completeness due to persistent systematics. Our findings and code provide a framework for interpreting TESS-derived rotation periods and inform the selection of quality cuts to optimize studies of stellar rotation, young associations, and gyrochronology.

Ultra-high energy neutrinos ($E>10^{17}$ eV) can provide insight into the most powerful accelerators in the universe, however their flux is extremely low. The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a detector concept which efficiently achieves sensitivity to this flux by employing phased radio arrays on mountains, which search for the radio emission of up-going extensive air showers created by Earth-skimming tau neutrinos. Here, we calculate the point-source effective area of BEACON and characterize its sensitivity to transient neutrino fluences with both short ($<15$ min) and long ($> 1$ day) durations. Additionally, by integrating the effective area, we provide an updated estimate of the diffuse flux sensitivity. With just 100 stations, BEACON achieves sensitivity to short-duration transients such as nearby short gamma-ray bursts. With 1000 stations, BEACON achieves a sensitivity to long-duration transients, as well as the cosmogenic flux, ten times greater than existing experiments at 1 EeV. With an efficient design optimized for ultrahigh energy neutrinos, BEACON is capable of discovering the sources of neutrinos at the highest energies.

The Faraday rotation measure (RM) is a commonly used tool to trace electron number density and magnetic fields in hot accretion flows, particularly in low-luminosity accreting supermassive black holes. We focus on the nuclear region of M87, which was observed at 230 GHz (1.3 mm) by the Event Horizon Telescope in 2019. It remains unclear whether this emission originates from the accretion flow, the jet base, or both. To probe the presence of an accretion flow, we explore the scenario where the linearly polarized emission from the counter-jet, visible at 43 GHz (7 mm), is Faraday-rotated by the accretion flow. We calculate theoretical predictions for counter-jet polarization using analytical and numerical models. In all cases, we find a Faraday-thick flow at 43 GHz (7 mm), with $\mathrm{RM} \sim 10^6$ rad m$^{-2}$, and a polarization angle that follows a linear relationship with wavelength squared, consistent with external Faraday rotation. The more realistic model, which includes turbulence and magnetic field fluctuations, predicts that the polarization pattern should be time-dependent, and that the counter-jet emission is depolarized due to Faraday depth fluctuations across the accretion flow. Despite the Faraday thick regime and strong depolarization, the linear relationship persists, enabling us to constrain the flow's physical properties. Comparing the counter-jet and forward-jet linear polarization states should enable detection of M87's accretion flow and provide lower limits on electron density, magnetic field strength, and mass accretion rate.

Galaxy clusters provide a unique environment to study galaxy evolution. The role of cluster dynamical states in shaping the physical and morphological properties of member galaxies remains an open question. We aim to assess the impact of the dynamical state of massive ($M_{500} \geq 1.5 \times 10^{14} M_{\odot}$) galaxy clusters on the physical and structural properties of their member galaxies, and also in their fundamental relations in the redshift range $0.10 < z < 0.35$. We use a mass-matched sample of galaxies from relaxed and disturbed clusters. Morphological types are assigned using both parametric and non-parametric methods, while physical properties are derived through SED fitting. Galaxies are further divided into subpopulations to investigate trends with cluster dynamical states. The dynamical state of galaxy clusters does not alter their fundamental relations at low redshift (such as color-magnitude, mass-size, morphology-density, and SF-density relations), nor does it significantly affect the mean or dispersion of galaxy properties. However, it does impact the distributions at the level of third and fourth order moments, introducing asymmetries and heavier tails in the properties of galaxies. The greatest effects are observed in low-mass and red sequence galaxies. These findings suggest that, at low redshift, the fundamental relations of massive galaxy clusters are already well-established and resilient to recent dynamical activity. Nonetheless, the influence of the dynamical state on the higher-order moments of galaxy properties indicates that environmental processes associated with disturbed clusters still leave measurable imprints, particularly on low-mass and red sequence galaxies. This is consistent with the idea that galaxy evolution is shaped both by early pre-processing and by subsequent interactions within dynamically active environments.

We investigate the cosmological evolution of the luminosity and redshift of FRBs. As is the case for all extragalactic sources, we are dealing with data that are truncated by observational selection effects, the most important being the flux limit, which introduces the so-called Eddington-Malmquist bias. In addition, for FRBs, there is a significant uncertainty in the redshifts obtained from the observed dispersion measures. To correct for the truncation we use the non-parametric, non-binning Efron- Petrosian and Lynden-Bell methods, which give unbiased distributions of luminosities and redshifts and their cosmological evolution. To quantify the redshift uncertainty, we use a data set, which in addition to a mean redshift, gives the one-sigma errors. We construct three samples with lower, mean, and upper redshifts and apply the above methods to each. For the three samples, we find similar (1) > 2.5{\sigma} evidence for luminosity evolution, (2) a luminosity function that can be fit by a simple broken power law, and (3) a comoving density formation rate that decreases rapidly with redshift unlike the cosmic star formation rate (SFR). This rate is similar to that of short gamma-ray bursts, which are believed to result from compact star mergers with a formation rate delayed relative to the SFR. This may further support the hypothesis that magnetars are the progenitors of FRBs.

The unstable accretion phases during pre-main-sequence evolution of T Tauri stars produce variable irradiation and heating of planet-forming regions. A strong accretion outburst was observed with Spitzer-IRS in 2008 in EX Lup, the prototype of EXor variables, and found to increase the mid-infrared water and OH emission and decrease organic emission, suggesting large chemical changes. We present here two JWST-MIRI epochs of quiescent EX Lup in 2022 and 2023 obtained over a decade after the 2008 outburst and several months after a moderate burst in 2022. With JWST's sharper spectral view, we can now analyze water emission as a function of temperature in the two MIRI epochs and, approximately, also in the previous Spitzer epochs. This new analysis shows a strong cold water vapor ``burst" in low-energy lines during the 2008 outburst, which we consider clear evidence for enhanced ice sublimation due to a recession of the snowline, as found in protostellar envelopes. JWST shows that EX Lup still has an unusually strong emission from cold water in comparison to other T Tauri disks, suggesting > 10-yr-long freeze-out timescales in the inner disk surface. EX Lup demonstrates that outbursts can significantly change the observed organic-to-water ratios and increase the cold water reservoir, providing chemical signatures to study the recent accretion history of disks. This study provides an unprecedented demonstration of the chemical evolution triggered by accretion outbursts in the Class II phase and of the high potential of time-domain experiments to reveal processes that may have fundamental implications on planet-forming bodies near the snowline.

Nowadays, one of the well-known serious challenges in cosmology is the Hubble tension, namely the discrepancy between the Hubble constants from the local observation of Type Ia supernova (SNIa) and the high-$z$ observation of cosmic microwave background (CMB). Here, we are interested in alleviating the Hubble tension with a local void. The key idea is assuming that we live in a locally underdense void, where one will feel a faster expansion rate compared to the cosmic average. In the literature, it was found that a local void cannot satisfyingly alleviate the Hubble tension, since it is not preferred over the $\Lambda$CDM model by the observations such as the Pantheon SNIa sample, especially in terms of the information criteria AIC and BIC. In the present work, we try to alleviate the Hubble tension with a local void and transitions of the absolute magnitude $M$, by using the Pantheon+ SNIa sample alone or jointly with the CMB data of Planck 2018. We find that the Hubble tension can be satisfyingly alleviated, while the $\Lambda$LTB void models are strongly preferred by the observations.

Context. Large-amplitude inversions of the solar wind's interplanetary magnetic field have long been documented; however, observations from the Parker Solar Probe (PSP) mission have renewed interest in this phenomenon as such features, often termed switchbacks, may constrain both the sources of the solar wind as well as in-situ nonlinear dynamics and turbulent heating. Aims. We aim to show that magnetic field fluctuations in the solar wind are consistent with Alfvénic fluctuations that naturally form switchback inversions in the magnetic field through expansion effects. Methods. We examine PSP observations of the evolution of a single stream of solar wind in a radial scan from PSP's tenth perihelion encounter from approximately 15-50 solar radii. We study the growth and radial scaling of normalized fluctuation amplitudes in the magnetic field, $\delta B/B$, within the framework of spherical polarization. We compare heating rates computed via outer-scale decay from consideration of wave-action to proton heating rates empirically observed through considering adiabatic expansion. Results. We find that the magnetic field fluctuations are largely spherically polarized and that the normalized amplitudes of the magnetic field, $\delta B/B$, increases with amplitude. The growth of the magnetic field amplitude leads to switchback inversions in the magnetic field. While the amplitudes do not grow as fast as predicted by the conservation of wave action, the deviation from the expected scaling yields an effective heating rate, which is close to the empirically observed proton heating rate. Conclusions. The observed scaling of fluctuation amplitudes is largely consistent with a picture of expanding Alfvén waves that seed turbulence leading to dissipation. The expansion of the waves leads to the growth of wave-amplitudes, resulting in the formation of switchbacks.

Low-surface brightness galaxies (LSBGs) are defined as galaxies with central surface brightness levels fainter than the night sky, making them challenging to observe. A key open question is whether their faint appearance arises from intrinsic properties or stochastic events in their formation histories. We aim to trace the formation histories of LSBGs to assess whether their evolutionary paths differ from those of high-surface brightness galaxies (HSBGs), and to identify the key physical drivers behind these differences. We present a fast and efficient method to estimate stellar surface brightness densities in hydro-dynamical simulations and a statistically robust exploration of over 150 properties in the reference run \textsc{Ref-L0100N1504} of the \texttt{EAGLE} simulation. To minimise biases, we carefully match the stellar and halo mass distributions of the selected LSB and HSB samples. At $z=0$, LSBGs are typically extended, rotation-supported systems with lower stellar densities, older stellar populations, reduced star formation activity, and higher specific stellar angular momenta $j_*$ than their HSBG counterparts. They also exhibit larger radii of maximum circular velocity ($R_{\mathrm{Vmax}}$). We identify key transition redshifts that mark the divergence of LSBG and HSBG properties: $j_*$ diverges at $z\sim5-7$ and $R_{\mathrm{Vmax}}$ at $z\sim2-3$. Star formation activity and large-scale environment seem to play only a minimal role in the development of LSB features. LSBGs follow mass-dependent evolutionary pathways, where early rapid formation and later slowdowns, combined with their distinct structural properties, influence their response to external factors like mergers and gas accretion. Their LSB nature emerges from intrinsic dynamical and structural factors rather than environmental influences, with angular momentum as a key driver of divergence at high redshifts.

Supermassive black holes (SMBHs) imprint gravitational signatures on the matter within their sphere of influence (SoI). Nuclear gas dynamics can hence be used to accurately measure the mass of an SMBH, yet such measurements remain elusive in the early Universe. We report the first dynamical measurement of an SMBH mass at $z >$ 2, based on high spatial resolution observations of the [C II] emission line that resolve the SoI in an obscured quasar at $z$ = 4.6. The velocity dispersion rises radially toward the center, requiring the presence of a 6.3$~\pm~0.14$ $\times$ 10$^9~\rm M_{\odot}$ SMBH. We propose that obscured quasars allow [C II] survivability in the inner regions, and may be ideal targets for increasing dynamical SMBH mass estimates in the early Universe.

Context: With the advancement of solar physics research, next-generation solar space missions and ground-based telescopes face significant challenges in efficiently transmitting and/or storing large-scale observational data. Aims: We develop an efficient compression and evaluation framework for solar EUV data, specifically optimized for Solar Orbiter Extreme Ultraviolet Imager (EUI) data, significantly reducing data volume while preserving scientific usability. Methods: We systematically evaluated four error-bounded lossy compressors across two EUI datasets. However, the existing methods cannot perfectly handle the EUI datasets (with continuously changing distance and significant resolution differences). Motivated by this, we develop an adaptive hybrid compression strategy with optimized interpolation predictors. Moreover, we designed a two-stage evaluation framework integrating distortion analysis with downstream scientific workflows, ensuring that observational analysis is not affected at high compression ratios. Results: Our framework SolarZip achieved up to 800x reduction for Full Sun Imager (FSI) data and 500x for High Resolution Imager (HRI$_{\text{EUV}}$) data. It significantly outperformed both traditional and advanced algorithms, achieving 3-50x higher compression ratios than traditional algorithms, surpassing the second-best algorithm by up to 30%. Simulation experiments verified that SolarZip can reduce data transmission time by up to 270x while ensuring the preservation of scientific usability. Conclusions: The SolarZip framework significantly enhances solar observational data compression efficiency while preserving scientific usability by dynamically selecting optimal compression methods based on observational scenarios and user requirements. This provides a promising data management solution for deep space missions like Solar Orbiter.

Surface brightness-colour relations (SBCRs) are widely used to determine the angular diameters of stars. They are in particular used in the Baade-Wesselink (BW) method of distance determination of Cepheids. However, the impact of the SBCR on the BW distance of Cepheids is about 8%, depending on the choice of SBCR considered in the literature. We aim to calibrate a precise SBCR dedicated to Cepheids using the best quality interferometric measurements available as well as different photometric bands, including the Gaia bands. We selected interferometric and photometric data in the literature for seven Cepheids covering different pulsation periods. From the phased photometry in the different bands (VJHKG$\mathrm{G_{BP}G_{RP}}$) corrected from extinction and the interferometric limb-darkened angular diameters, we calculated the SBCR associated with each combination of colours. We first find that the seven Cepheids have consistent SBCRs as long as the two magnitudes considered are not too close in wavelengths. For the SBCR ($\mathrm{F_{V},V-K}$): $\mathrm{F_{V} = -0.1336_{\pm 0.0009}(V-K)_{0}+3.9572_{\pm 0.0015}}$, we obtain a root mean square (RMS) of 0.0040 mag, which is three times lower than the latest estimate from 2004. Also, for the first time, we present an SBCR dedicated to Cepheids based on Gaia bands only: $\mathrm{F_{G_{BP}} = -0.3001_{\pm 0.0030}(G_{BP}-G_{RP})_{0}+3.9977_{\pm 0.0029}}$, with an excellent RMS of 0.0061 mag. However, using theoretical models, we show that this SBCR is highly sensitive to metallicity. From this empirical multi-wavelength approach, we also show that the impact of the CircumStellar Environment (CSE) of Cepheids emission is not negligible and should be taken into account in the future.

Redshift drift effect, an observational probe that indenpendent of cosmological models, presents unique applications in specific cosmological epoch. By quantifying redshift drift signal , researchers can determine the rate of the Universe's accelerated expansion and impose constraints on cosmological models and parameters. This study evaluates the precision in cosmological parameters estimation derived from this signal via HI 21cm signal, that observed by the Square Kilometre Array (SKA) telescope, with spectral resolutions of 0.001 Hz and 0.002 Hz over an observational period of $\Delta T = 0.5$ year, utilizing two established techniques: the canonical redshift drift and the differential redshift drift method. The primary objective of this project is to ascertain the rate of cosmic acceleration and establish a solid foundation for real-time cosmology. The results reveal that both the two methods impose highly precise constraints on cosmological parameters, with accuracy reaching the level of millimeter per second (mm/s) or better. However, the canonical method provides relatively less stringent compared to the differential approach. Furthermore, when solely constraining the matter density parameter $\Omega_m$, the strategy can be adapted to the canonical method. Nonetheless, the differential method exhibits clear advantages when simultaneously constraining the matter density parameter $\Omega_m$ and the equation of state of dark energy. These findings validate SKA's capability in detecting redshift drift and refining observational cosmology and indicates the effect can offer superior diagnostic capabilities compared to other techniques, provided that appropriate observational equipment or sufficient observational time is employed.

Supermassive black hole mergers with spin-flips accelerate energetic particles through their precessing relativistic jets, producing high energy neutrinos and finally gravitational waves. In star formation massive stars come in pairs, triplets and quadruplets, allowing second generation mergers of the remnants with discrepant spin directions. The Gravitational Wave (GW) data support such a scenario. Earlier we suggested that stellar mass black hole mergers (visible in M82) with an associated spin-flip analogously allow the acceleration of energetic particles, with ensuing high energy neutrinos and high energy photons, and finally producing gravitational waves. At cosmic distances only the gravitational waves and the neutrinos remain detectable. Here we generalize the argument to starburst and normal galaxies throughout their cosmic evolution, and show that these galaxies may dominate over Active Galactic Nuclei (AGN) in the flux of ultra-high energy particles observed at Earth. All these sources contribute to the cosmic neutrino background, as well as the gravitational wave background (they detected the lower frequencies). We outline a search strategy to find such episodic sources, which requires to include both luminosity and flux density.

In this work, we examine the association between solar active regions and 152 solar flares, coronal mass ejections, and solar energetic particle (SEP) events over solar cycles 23-24 (1997-2017). The CDAW center's GOES data in the energy channel >10 MeV (Major SEPs; solar proton events) with flux >= 10 pfu was used for our investigation. For the associated activities, we have analyzed the data from space born satellites namely: SOHO/LASCO and SDO/AIA. We found a moderate correlation (55 %) between SXR flux and sunspot area i.e., active regions with larger sunspot areas generally generate larger flares. We found that most of the SEPs are originated from the magnetically complex active regions i.e., hale class beta-gamma-delta and beta. Very few events were associated with unipolar active regions. Stronger GOES X-ray is linked to more impulsive events, as evidenced by the negative correlation (-0.40) between X-ray flux and SEP duration. In the active region beta-gamma-delta, the highest average SEP intensity (2051 pfu) was detected. In the data set used, only 10 % SEPs are found impulsive in nature, while the remaining 90 % are gradual in nature. All the impulsive events had SEP intensity less than 100 pfu and most of the CMEs associated with these events were decelerated CMEs. We discovered that the majority of faster CMEs are linked to the most complex magnetic active regions. This indicates that high speed CMEs are produced by magnetically complex active regions. We discovered that 58 SEP events in our data set are linked to accelerated CMEs, while 82 are linked to decelerated CMEs. The highest average CME width is found corresponding to magnetically most complex active regions beta-delta, gamma-delta, alpha-gamma-delta and beta-gamma-delta, which shows that large CMEs are the consequences of magnetically complex active regions.

We report on a detailed study of a luminous, heavily obscured ($N_{\rm H} \sim 2 \times 10^{23}$ cm$^{-2}$), radio-loud quasar SRGAJ230631.0+155633, discovered in the 4--12 keV energy band by the Mikhail Pavlinsky ART-XC telescope aboard the SRG observatory during the first two years of its all-sky X-ray survey in 2020--2021. The object is located at $z=0.4389$ and is a type 2 AGN according to optical spectroscopy (SDSS, confirmed by DESI). Our analysis combines data from the radio to the X-ray energy range, including quasi-simultaneous pointed observations with the SRG/ART-XC and Swift/XRT telescopes, conducted in June 2023. During these follow-up observations, the source was found in a significantly fainter but still very luminous state ($L_{\rm X}=1.0^{+0.8}_{-0.3} \times 10^{45}$ erg s$^{-1}$, absorption corrected, 2--10 keV) compared to its discovery during the all-sky survey ($L_{\rm X}=6^{+6}_{-3}\times10^{45}$ erg s$^{-1}$), which indicates significant intrinsic variability on a rest-frame time scale of $\sim 1$ year. The radio data show a complex morphology with a core and two extended radio lobes, indicating a giant FRII radio galaxy. Using multiwavelength photometry and the black hole--bulge mass scaling relation, we estimate the bolometric luminosity of the quasar at $\sim 6\times 10^{46}$ erg s$^{-1}$ and the mass of its central black hole at $\sim 1.4 \times 10^9$ $M_\odot$. This implies that the black hole is accreting at $\sim 30$ of the Eddington limit. Overall, SRGAJ230631.0+155633 proves to be one of the most luminous obscured quasars in the observable Universe out to $z=0.5$ (i.e. over the last 5 billion years of cosmic time). As such, it can serve as a valuable testbed for in-depth exploration of the physics of such objects, which were much more abundant in the younger Universe.

Understanding how supermassive black holes (SMBHs) form in the early universe is one of the most challenging problems in astrophysics. Their high abundance in the first billion years, as observed by the James Webb Space Telescope, hints towards black hole seeds that accrete mass rapidly. The origin of this accreted mass is not known. Here, we consider a billion solar mass clumpy galaxy at z=5.48 with a 30 million solar mass black hole in the center. We show that the clumps should migrate to the central region because of torques from dynamical friction with the halo, funneling in at least 14 solar masses per year. This is fast enough to grow the observed SMBH, with only 1% of the accreted mass getting in and the rest going to a bulge. Clump-fed accretion could explain most young SMBHs because young galaxies are highly irregular with massive star-forming clumps.

We report MIRI-JWST coronagraphic observations at 11.3 and 15.5 mic of the debris disk around the young star HD 106906. The observations were made to characterize the structure, temperature and mass of the disk through the thermal emission of the dust heated by the central star. Another goal was also to constrain the size distribution of the grains. The data were reduced and calibrated using the JWST pipeline. The analysis was based on a forward-modeling of the images using a multiparameter radiative transfer model coupled to an optical code for coronagraphy processing. The disk is clearly detected at both wavelengths. The slight asymmetry is geometrically consistent with the asymmetry observed in the near-IR, but it is inconsistent the brightness distribution. The observed structure is well reproduced with a model of a disk (or belt) with a critical radius 70 au, a mildly inward-increasing density (index 2) and a steeper decrease outward (index -6). This indication of a filled disk inside the critical radius is inconsistent with sculpting from an inner massive planet. The size distribution of the grains that cause the mid-IR emission is well constrained by the flux ratio at the two wavelengths : 0.45 10 mic and 0.65 10 mic for silicate and graphite grains, respectively. The minimum size is consistent with predictions of blowout through radiative pressure. We derive a mass of the dust that causes the mid-IR emission of 3.3 5.0 E3 Mearth. When the larger grains (up to 1 cm) that cause the millimeter emission are included, we extrapolate this mass to 0.10 0.16 Mearth. We point out to that this is fully consistent with ALMA observations of the disk in terms of dust mass and of its millimeter flux. We estimate the average dust temperature in the planetesimal belt to be 74 K, and a temperature range within the whole disk from 40 to 130 K.

Recent studies suggest that numerous intermediate-mass black holes (IMBHs) may wander undetected across the Universe, emitting little radiation. These IMBHs largely preserve their birth masses, offering critical insights into the formation of heavy black hole seeds and the dynamical processes driving their evolution. We propose that such IMBHs could produce detectable microlensing effects on quasars. Their Einstein radii, comparable to the scale of quasar broad-line regions, magnify radiation from the accretion disk and broad emission lines, making these quasars outliers in flux scaling relations. Meanwhile, the microlensing causes long-term, quasi-linear variability that is distinguishable from the stochastic variability of quasars through its coherent multi-wavelength behavior. We develop a matched-filtering technique that effectively separates the long-term lensing signal from the intrinsic quasar variability, with sensitivity tripling each time the observational time span doubles. Moreover, as IMBHs are often surrounded by dense star clusters, their combined gravitational field produces substantial extended, concentric caustics. These caustics induce significant variability in optical, ultraviolet, and X-ray bands over decade timescales, alongside hour-to-day-scale flux fluctuations in broad emission lines. We predict a substantial number of detectable events in the upcoming surveys by the Vera C. Rubin Observatory, considering recent IMBH mass density estimates. Even in the absence of positive detections, searches for these microlensing signals will place meaningful constraints on the cosmological mass density of IMBHs, advancing our understanding of their role in cosmic evolution.

Chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy is a versatile technique to record broadband gas-phase rotational spectra, enabling detailed investigations of molecular structure, dynamics, and hyperfine interactions. Here, we present the development and application of a CP-FTMW spectrometer operating in the 6.5-18 GHz frequency range, studying cyanocyclohexane, 1-cyanocyclohexene, and 4-cyanocyclohexene using a heated pulsed supersonic expansion source. The dynamic range, experimental resolution, and high sensitivity enable observation of multiple conformers, precise measurements of hyperfine splitting arising from nuclear quadrupole coupling due to the nitrogen atom in the cyano group, as well as the observation of singly $^{13}$C- and $^{15}$N-substituted isotopic isomers in natural abundance. Using the latter, precise structures for the molecules are derived. The accurate rotational spectra enabled a search for these species toward the dark, cold molecular cloud TMC-1; no signals are found, and we discuss the implications of derived upper limits on the interstellar chemistry of the cyanocyclohexane family.

Fast radio bursts (FRBs) are radio pulses that originate from cosmological distance. Over 800 FRB sources with thousands of bursts have been detected, yet their origins remain unknown. Analyse of the energy function and the redshift evolution of volumetric rate could provide crucial insights into FRB progenitors. In this paper, we present the energy functions of non-repeaters selected from the CHIME/FRB baseband data using the $V_\mathrm{max}$ method. The $V_\mathrm{max}$ method allows us to measure redshift evolution without prior assumptions. We observed Schechter-like shapes in the energy function at low redshift region, while high redshift regions show a relatively small slope ($\gamma\approx -2$). The redshift evolution of volumetric rates shows an ambiguous trend, indicating that the population of non-repeaters is still not well understood. In the future, more samples and accurate measurements are needed to clarify these trends.

The Galactic edge at Galactocentric distances of 14\,--\,22\,kpc provides an ideal laboratory to study molecular clouds in an environment that is different from the solar neighborhood, due to its lower gas density, lower metallicity, and little or no perturbation from the spiral arms. Observations of CO\,($J$\,=\,2--1) spectral lines were carried out towards 72 molecular clouds located at the Galactic edge using the IRAM\,30\,m telescope. Combined with CO\,($J$\,=\,1--0) data from the MWISP project, we investigate the variations of $R_{21}$ across these Galactic edge clouds, with $R_{21}$ representing CO(2-1)/CO(1-0) integrated intensity ratios. These are found to range from 0.3 to 3.0 with a mean of 1.0\,$\pm$\,0.1 in the Galactic edge clouds. The proportions of very low ratio gas (VLRG; $R_{21}$\,<\,0.4), low ratio gas (LRG; 0.4\,$\le$\,$R_{21}$\,<\,0.7), high ratio gas (HRG; 0.7\,$\le$\,$R_{21}$\,<\,1.0), and very high ratio gas (VHRG; $R_{21}$\,$\ge$\,1.0) are 6.9\%, 29.2\%, 26.4\%, and 37.5\%, respectively, indicating a significant presence of high $R_{21}$ ratio molecular gas within these regions. In our Galaxy, the $R_{21}$ ratio exhibits a gradient of initial radial decline followed by a high dispersion with increasing Galacticentric distance and a prevalence for high ratio gas. There is no apparent systematic variation within the Galactocentric distance range of 14 to 22\,kpc. A substantial proportion of HRG and VHRG is found to be associated with compact clouds and regions displaying star-forming activity, suggesting that the high $R_{21}$ ratios may stem from dense gas concentrations and recent episodes of star formation.

Massive stars are significant sites for the weak s-process (ws-process). $^{22}$Ne and $^{16}$O are, respectively, the main neutron source and poison for the ws-process. In the metal-poor stars, the abundance of $^{22}$Ne is limited by the metallicity, so that the contribution of $^{22}$Ne($\alpha$, n)$^{25}$Mg reaction on the s-process is small. Conversely, the $^{17}$O($\alpha$, n)$^{20}$Ne reaction is more evident in more metal-poor stars due to the most abundant $^{16}$O in all metallicities. In this work, we calculate the evolution of four metal-poor models ($Z=10^{-3}$) for the Zero-Age Main-Sequence (ZAMS) masses of $M ({\rm ZAMS})=$ 15, 20, 25, and 30 M$_{\odot}$ to investigate the effect of reaction rates on the ws-process. We adopt the new $^{17}$O($\alpha$, n)$^{20}$Ne and $^{17}$O($\alpha, \gamma$)$^{21}$Ne reaction rates suggested by Wiescher et al. (2023) and $^{22}$Ne($\alpha$, n)$^{25}$Mg and $^{22}$Ne($\alpha, \gamma$)$^{26}$Mg from Best et al. (2013). The yields of the s-process isotope with updated reaction rates are compared with the results using default reaction rates from JINA REACLIB. We find that the effects of new $^{17}$O+$\alpha$ are much more significant than those of new $^{22}$Ne+$\alpha$ reaction rates in the non-rotation stars.

We investigate the effects of surface gravity, effective temperature, and cloudiness on the potassium doublet (\ion{K}{1}) at 1.17 {\mu}m in brown dwarf spectra. Using pseudo-Voigt profiles to fit the \ion{K}{1} doublet in Sonora Diamondback atmospheric model spectra, we find that gravity and cloudiness affect the spectra differently in mid to late-L dwarfs. The full-width at half-maximum (FWHM) is strongly correlated with surface gravity, while the maximum depth strongly correlates with cloudiness. This method allows us to separate the effects of clouds and surface gravity on the \ion{K}{1} 1.17 {\mu}m doublet. We also find that the FWHM and maximum depth of the doublet can help to estimate the effective temperature and surface gravity in early to mid-L dwarfs.

We explore the mass resonance structure that naturally arises from extra-dimensional models. The resonance can enhance the dark matter annihilation as well as self-interaction. We demonstrate such a resonance structure by considering the fermionic dark matter and dark photon models on an $S^1/(Z_2 \times Z_2')$ orbifold. We also note that this model embeds dark matter axial vector coupling to the dark photon, which opens up the viable dark matter parameter space. We then present the unique predictions for direct-detection experiments and accelerator searches.

Low-mass dark matter (DM) subhalos are pivotal in understanding the small-scale structure of the universe, thereby offering a sensitive method to discriminate between different cosmological models. In this study, we estimate the local number density of cold DM subhalos in the solar neighborhood, and demonstrate that their sparse distribution makes their detection via direct detection experiments highly improbable. However, it is plausible to expect that an $\mathcal{O}(1)$ number of subhalos could be detected by Paleo-detectors, a proposed new technique to look for DM by reading out damage tracks left by past DM interactions in minerals, due to their extended exposure times. Hence, we explore how Paleo-detectors can serve as effective probes for the properties of low-mass subhalos, $\mathcal{O}(10^{-5}-10^8) M_{\odot}$. We find that Paleo-detectors might be able to constrain certain regions of the subhalo mass-concentration relation (for subhalo masses of $10-10^4 M_\odot$ if DM has a mass of $\sim5$GeV). This is a new and complementary type of study that seeks to combine information from the particle nature of DM to that of small scale structures.

We propose heavy axions as a natural superheavy dark matter candidate in string theory, with the relic density of dark matter originating in quantum fluctuations during cosmic inflation. String Theory is well known for the possibility of having tens to hundreds of axion-like particles -- the axiverse. Moduli stabilization generates high-scale masses for many of these, placing them naturally in the superheavy regime of particle physics. We consider moduli stabilization in the KKLT framework, featuring a single volume modulus and $C_4$ axion, and a fiducial inflation model minimally coupled to the volume modulus. We demonstrate that both the volume modulus and the axion can be abundantly produced through gravitational particle production. The former is unstable and readily decays to Standard Model particles while the latter (the axion) can be stable and survives to constitute the present day dark matter.

We investigated a modified Frolov black hole (BH) model that incorporates both a global monopole (GM) and a cosmic string (CS) to explore the interplay between non-singular BH regularization and topological defect effects. In our study, we derived a spacetime metric characterized by a regulated core through a length scale parameter $\alpha$ and introduced additional modifications via the GM parameter $\eta$ and the CS parameter $a$, which collectively alter the horizon structure and causal geometry of the BH. We analyzed the thermodynamic properties by deriving expressions for the mass function, Hawking temperature, and entropy, and found that the inclusion of GM and CS significantly deviates the BH entropy from the conventional Bekenstein-Hawking area law, while numerical investigations showed that the shadow radius exhibits contrasting behaviors: the Frolov parameters tend to reduce the shadow size whereas the topological defects enhance it. Furthermore, we examined the dynamics of scalar and electromagnetic perturbations by solving the massless Klein-Gordon equation in the BH background and computed the quasinormal modes (QNMs) using the WKB approximation, which confirmed the BH's stability and revealed that the oscillation frequencies and damping rates are strongly dependent on the parameters $\alpha$, $q$, $\eta$, and $a$. Our results suggest that the distinct observational signatures arising from this composite BH model may provide a promising avenue for testing modified gravity theories in the strong-field regime.

We study the evolution of Q-balls under a spontaneously broken global $U(1)$ symmetry. Q-balls are stabilized by the conservation of $U(1)$ charge, but when the symmetry is spontaneously broken, the resulting Nambu-Goldstone (NG) boson can carry charge away from the Q-ball, potentially leading to charge leakage. To study this process in a controlled setting, we consider a scenario where Q-balls first form under an unbroken $U(1)$ symmetry, which is then spontaneously broken. We introduce two complex scalar fields: one responsible for forming the Q-ball, and the other for spontaneously breaking the $U(1)$ symmetry, allowing us to clearly separate the formation and symmetry-breaking phases. Using numerical simulations in a spherically symmetric system, we find that the evolution of Q-balls depends sensitively on the structure of the interaction between the two fields and the magnitude of symmetry breaking. Depending on parameters, Q-balls can completely decay, evaporate into smaller, stable Q-balls, or transition into oscillons/I-balls. In particular, we find that stable, localized remnants often survive the evolution over long timescales, especially when the symmetry-breaking scale is small. These results demonstrate that, even though spontaneous $U(1)$ breaking can lead to significant energy and charge loss from Q-balls, stable localized objects with reduced or no charge can frequently survive and potentially contribute to cosmological relics.

Q-balls are non-topological solitons that arise in theories with a complex scalar field possessing a conserved global U(1) charge. Their stability is ensured by this charge, making them potentially significant in cosmology. In this paper, we investigate Q-ball-like objects in scenarios where the scalar field acquires a finite vacuum expectation value, spontaneously breaking the global U(1) symmetry. A well-motivated example is the Peccei-Quinn field, where the U(1) symmetry is identified as the Peccei-Quinn symmetry, and hence we refer to such objects as PQ-balls. We first discuss the existence of stable PQ-ball solutions in a finite-density plasma and argue that they become unstable in vacuum. Using detailed numerical simulations under spherical symmetry, we confirm their formation, compute their decay rate, and derive an analytical formula for it. Our results have important implications for axion cosmology, particularly in the context of the kinetic misalignment mechanism.

We derive the coupled dynamics between the bubble wall and the plasma from first principles using nonequilibrium quantum field theory. The commonly used equation of motion of the bubble wall in the kinetic approach is shown to be incomplete. In the language of the two-particle-irreducible effective action, the conventional equation misses higher-loop terms generated by the condensate-particle type vertices (e.g.,~$\varphi\phi\chi^2$, where $\varphi$ is the background field describing the bubble wall, $\phi$ the corresponding particle excitation and $\chi$ another particle species in the plasma). From the missing terms, we identify an additional dissipative friction which is contributed by particle production processes from the condensate-particle type vertices. We also show how other transmission processes beyond the 1-to-1 elementary transmission studied in the literature for ultrarelativistic bubble walls, e.g., 1-to-1 mixing and 1-to-2 transition radiation, can be understood from the kinetic approach.