Papers for Friday, Aug 11 2023

The mass assembly history (MAH) of dark matter halos plays a crucial role in shaping the formation and evolution of galaxies. MAHs are used extensively in semi-analytic and empirical models of galaxy formation, yet current analytic methods to generate them are inaccurate and unable to capture their relationship with the halo internal structure and large-scale environment. This paper introduces FLORAH, a machine-learning framework for generating assembly histories of ensembles of dark matter halos. We train FLORAH on the assembly histories from the GUREFT and VSMDPL N-body simulations and demonstrate its ability to recover key properties such as the time evolution of mass and concentration. We obtain similar results for the galaxy stellar mass versus halo mass relation and its residuals when we run the Santa Cruz semi-analytic model on FLORAH-generated assembly histories and halo formation histories extracted from an N-body simulation. We further show that FLORAH also reproduces the dependence of clustering on properties other than mass (assembly bias), which is not captured by other analytic methods. By combining multiple networks trained on a suite of simulations with different redshift ranges and mass resolutions, we are able to construct accurate main progenitor branches (MPBs) with a wide dynamic mass range from $z = 0$ up to an ultra-high redshift $z \approx 20$, currently far beyond that of a single N-body simulation. FLORAH is the first step towards a machine learning-based framework for planting full merger trees; this will enable the exploration of different galaxy formation scenarios with great computational efficiency at unprecedented accuracy.

We present a study of the molecular gas of seven early-type galaxies with high angular resolution data obtained as part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project with the Atacama Large Millimeter/submillimeter Array. Using a fixed spatial scale approach, we study the mass surface density ($\Sigma$) and velocity dispersion ($\sigma$) of the molecular gas on spatial scales ranging from $60$ to $120$pc. Given the spatial resolution of our data ($20$ - $70$pc), we characterise these properties across many thousands of individual sight lines ($\approx50,000$ at our highest physical resolution). The molecular gas along these sight lines has a large range ($\approx2$dex) of mass surface densities and velocity dispersions $\approx40\%$ higher than those of star-forming spiral galaxies. It has virial parameters $\alpha_\mathrm{vir}$ that depend weakly on the physical scale observed, likely due to beam smearing of the bulk galactic rotation, and is generally super-virial. Comparing the internal turbulent pressure ($P_\mathrm{turb}$) to the pressure required for dynamic equilibrium ($P_\mathrm{DE}$), the ratio $P_\mathrm{turb}$/$P_\mathrm{DE}$ is significantly less than unity in all galaxies, indicating that the gas is not in dynamic equilibrium and is strongly compressed, in apparent contradiction to the virial parameters. This may be due to our neglect of shear and tidal forces, and/or the combination of three-dimensional and vertical diagnostics. Both $\alpha_\mathrm{vir}$ and $P_\mathrm{turb}$ anti-correlate with the global star-formation rate of our galaxies. We therefore conclude that the molecular gas in early-type galaxies is likely unbound, and that large-scale dynamics likely plays a critical role in its regulation. This contrasts to the giant molecular clouds in the discs of late-type galaxies, that are much closer to dynamical equilibrium.

Throughout the past three decades, only a few tens of observations have been made of optical flashes contemporaneous with gamma-ray bursts (GRBs), despite the thousands of GRBs that have been detected during that same timeframe. In this work, we present light curves from the Transiting Exoplanet Survey Satellite (TESS) for a sample of 7 GRBs that were localized to within 10" by the Swift X-ray Telescope. For each burst, we characterize both the prompt emission, if it exists, and the afterglow, and conduct searches for late-time emission from a supernova or kilonova component. We also constrain the physical parameters of the burst based on the TESS light curve, and present a novel method to account for the effects of TESS's cosmic ray mitigation strategy on the observed flux from these GRBs. This allows us to establish upper limits on the true magnitude of any GRB-associated optical flash. Finally, we discuss how TESS's continuous monitoring and new weekly downlink schedule are proving invaluable in the rapid follow-up and characterization of short-duration transients, including GRBs; these could potentially enable TESS to detect electromagnetic counterparts to gravitational-wave events.

When observing transmission spectra produced by atmospheres of ultra-hot Jupiters, large telescopes are typically the instrument of choice due to the very weak signal of the planet's atmosphere. This study aims to alleviate the desire for large telescopes by illustrating that the same science is possible with smaller telescope classes. We use the cross-correlation technique to showcase the potential of the high-resolution spectrograph FOCES at Wendelstein Observatory and demonstrate its potential to resolve the atmosphere of the ultra-hot Jupiter, KELT-9 b. A performance comparison is conducted between FOCES and HARPS-N spectrographs, considering both single transit and combined observations over three nights. With FOCES, we have detected seven species in KELT-9 b's atmosphere: Ti II, Fe I, Fe II, Na I, Mg I, Na II, Cr II, Sc II. Although HARPS-N surpasses FOCES in performance, our results reveal that smaller telescope classes are capable of resolving ultra-hot Jupiter atmospheres. This broadens the scope of potential studies, allowing for investigations into phenomena like temporal variations in atmospheric signals and the atmospheric loss characteristics of these close-in planets.

Eclipsing of the X-ray emitting region in active galactic nuclei (AGN) is a potentially powerful probe to examine the AGN environment and absorber properties. Here we study the eclipse data from the 2016 XMM-Newton observation of NGC 6814 using a colour-colour analysis. Colours (i.e. hardness ratios) can provide the advantage of better time-resolution over spectral analysis alone. Colour-colour grids are constructed to examine the effects of different parameters on the observed spectral variability during the eclipse. Consistent with previous spectral analysis, the variations are dominated by changes in the column density and covering fraction of the absorber. However, during maximum eclipse the behaviour of the absorber changes. Just after ingress, the eclipse is described by changes in column density and covering fraction, but prior to egress, the variations are dominated by changes in column density alone. Simulations are carried out to consider possible absorber geometries that might produce this behaviour. The behaviour is inconsistent with a single, homogeneous cloud, but simulations suggest that multiple clouds, perhaps embedded in a highly ionised halo, could reproduce the results. In addition, we determine the orbital covering factor (fraction of orbital path-length) based on evidence of several eclipses in the 2016, 64-day Swift light curve. We estimate that ~ 2-4 per cent of the orbit is covered by obscuring clouds and that the distribution of clouds is not isotropic.

I report the discovery of a stellar stream (Sutlej) using Gaia DR3 proper motions and XP metallicities located ~15 degrees north of the Small Magellanic Cloud (SMC). The stream is composed of two parallel linear components ("branches") approximately ~8 x 0.6 degrees in size and separated by 2.5 degrees. The stars have a mean proper motion of (pmra,pmdec)=(+0.08 mas/yr,-1.41 mas/yr) which is quite similar to the proper motion of stars on the western side of the SMC. The color magnitude diagram of the stream stars has a clear red giant branch, horizontal branch, and main sequence turnoff that is well-matched by a PARSEC isochrone of 10 Gyr, [Fe/H]=-1.8 at 32 kpc and a total stellar mass of ~33,000 Msun. The stream is spread out over an area of 9.6 square degrees and has a surface brightness of 32.5 mag/arcsec^2. The metallicity of the stream stars from Gaia XP spectra extend over -2.5 < [M/H] < -1.0 with a median of [M/H]=-1.8. The tangential velocity of the stream stars is 214 km/s compared to the values of 448 km/s for the Large Magellanic Cloud and 428 km/s for the SMC. While the radial velocity of the stream is not yet known, a comparison of the space velocities using a range of assumed radial velocities, shows that the stream is unlikely to be associated with the Magellanic Clouds. The tangential velocity vector is misaligned with the stream by ~25 degrees which might indicate an important gravitational influence from the nearby Magellanic Clouds.

Inspired by the discussion in the community on possible hidden systematic errors in late universe cosmological probes and non-trivial physical models developed to reduce the Hubble tension, we investigate the Pantheon and Pantheon+ SNe samples for possible deviations from the original $\Lambda$CDM analysis. To simultaneously account for possible systematics or deviations from $\Lambda$CDM, we adopt Gaussian processes to model additional covariance while making no further assumptions on their origin. We explore both stationary and non-stationarity corrections to the covariance. While small changes in the inferred cosmological parameters $H_0$ and $\Omega_{m}$ can occur, we find no statistically significant evidence for missing covariance. We find an upper limit for the Gaussian processes amplitude $\sigma < 0.031$ mag with $95\%$ confidence, which corresponds to $20\%$ of the average statistical error in the Pantheon+ sample. The strongest effect we find on the inferred cosmological parameter posterior can reduce the statistical significance of the Hubble tension between Pantheon+ and Planck estimates from 5.3$\sigma$ to 4.5$\sigma$. Therefore, we conclude that the SN cosmological parameter inference is robust against the analysis modifications studied in this work.

Only a tiny fraction ~ 1% of stellar tidal disruption events (TDE) generate powerful relativistic jets evidenced by luminous hard X-ray and radio emissions. We propose that a key property responsible for both this surprisingly low rate and a variety of other observations is the typically large misalignment {\psi} between the orbital plane of the star and the spin axis of the supermassive black hole (SMBH). Such misaligned disk/jet systems undergo Lense-Thirring precession together about the SMBH spin axis. We find that TDE disks precess sufficiently rapidly that winds from the accretion disk will encase the system on large scales in a quasi-spherical outflow. We derive the critical jet efficiency {\eta} > {\eta}crit for both aligned and misaligned precessing jets to successfully escape from the disk-wind ejecta. As {\eta}crit is higher for precessing jets, less powerful jets only escape after alignment with the SMBH spin. Alignment can occur through magneto-spin or hydrodynamic mechanisms, which we estimate occur on typical timescales of weeks and years, respectively. The dominant mechanism depends on {\eta} and the orbital penetration factor \b{eta}. Hence depending only on intrinsic parameters of the event {{\psi},{\eta},\b{eta}}, we propose that each TDE jet can either escape prior to alignment, thus exhibiting erratic X-ray light curve and two-component radio afterglow (e.g., Swift J1644+57) or escape after alignment. Relatively rapid magneto-spin alignments produce relativistic jets exhibiting X-ray power-law decay and bright afterglows (e.g., AT2022cmc), while long hydrodynamic alignments give rise to late jet escape and delayed radio flares (e.g., AT2018hyz).

In this paper, we investigate a potential departure in the standard dark matter density evolution law, $\rho_{dm} = \rho_{dm,0}(1+z)^3$. The method involves considering a deformed evolution model, denoted as $\rho_{dm} = \rho_{dm,0}(1+z)^3f(z)$, and searching the presence of any deviation ($f(z)\neq 1$). As one may see, $f(z)$ is a general function that parametrizes a digression from the standard law. We use data of baryon acoustic oscillations, type I Supernovae luminosity distances, and galaxy cluster gas mass fraction observations to reconstruct $f(z)$ by Gaussian process regression. Unlike previous works, it enables us to investigate a possible deviation without using a specific function to describe it. We have obtained $f(z)=1$, the standard model scenario, within $2\sigma$ c.l. in all the considered cases.

The present work discusses the use of a weakly-supervised deep learning algorithm that reduces the cost of labelling pixel-level masks for complex radio galaxies with multiple components. The algorithm is trained on weak class-level labels of radio galaxies to get class activation maps (CAMs). The CAMs are further refined using an inter-pixel relations network (IRNet) to get instance segmentation masks over radio galaxies and the positions of their infrared hosts. We use data from the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, specifically the Evolutionary Map of the Universe (EMU) Pilot Survey, which covered a sky area of 270 square degrees with an RMS sensitivity of 25-35 $\mu$Jy/beam. We demonstrate that weakly-supervised deep learning algorithms can achieve high accuracy in predicting pixel-level information, including masks for the extended radio emission encapsulating all galaxy components and the positions of the infrared host galaxies. We evaluate the performance of our method using mean Average Precision (mAP) across multiple classes at a standard intersection over union (IoU) threshold of 0.5. We show that the model achieves a mAP$_{50}$ of 67.5\% and 76.8\% for radio masks and infrared host positions, respectively. The network architecture can be found at the following link: https://github.com/Nikhel1/Gal-CAM

The quasar HE0230$-$2130 is lensed by two galaxies at similar redshifts into four observed images. Using modeled quasar positions from fitting the brightness of the quasar images in ground-based imaging data from the Magellan telescope, we find that lens mass models where both galaxies are each parametrized with a singular power-law (PL) profile predict five quasar images. One of the predicted images is unobserved even though it is distinctively offset from the lensing galaxies and is bright enough to be observable. This missing image gives rise to new opportunities to study the galaxies' mass distribution. To interpret the quad configuration of this system, we test different profile assumption with the aim to obtain lens mass models that predicts correctly only four observed images. We test the effect of adopting cored profiles for the lensing galaxies, of external shear, and of additional profiles to represent a dark matter clump. By comparing the Bayesian evidence of different model parametrizations, we favor the model class that consists of two singular PL profiles for the lensing galaxies and a cored isothermal sphere in the region of the previously predicted fifth images (rNIS profile). We estimate the mass of the rNIS clumps inside its Einstein radius and find that 18\% are in the range $10^6 M_{\odot} \leq M_{\rm rNIS}\leq 10^9 M_{\odot}$, which is the predicted mass range of dark matter subhalos in cold dark matter simulations, or the mass of low-mass dark matter satellite galaxies. The second most likely model class, with a relative probability of 94\%, is the model where the smaller lensing galaxy is described by a cored PL profile with external shear. Our study demonstrates that lensed quasar images are sensitive to dark matter structure in the gravitational lens.

Understanding the spectral properties of sources is crucial for the characterization of the radio source population. In this work, we have extensively studied the ELAIS N1 field using various low-frequency radio observations. For the first time, we present the 1250\,MHz observations of the field using the upgraded Giant Meterwave Radio Telescope (uGMRT) that reach a central off-source RMS noise of $\sim 12\,\mu$Jy\,beam$^{-1}$. A source catalogue of 1086 sources is compiled at $5\sigma$ threshold ($>60\,\mu$Jy) to derive the normalized differential source counts at this frequency that is consistent with existing observations and simulations. We present the spectral indices derived in two ways: two-point spectral indices and by fitting a power-law. The latter yielded a median $\alpha = -0.57\pm 0.14$, and we identified nine ultra-steep spectrum sources using these spectral indices. Further, using a radio colour diagram, we identify the three mega-hertz peaked spectrum (MPS) sources, while three other MPS sources are identified from the visual inspection of the spectra, the properties of which are discussed. In our study of the classified sources in the ELAIS N1 field, we present the relationship between $\alpha$ and $z$. We find no evidence of an inverse correlation between these two quantities and suggest that the nature of the radio spectrum remains independent of the large-scale properties of the galaxies that vary with redshifts.

We use the Breit Pauli $R$-matrix method to calculate accurate energies and radiative data for states in C I up to $n$=30 and with $l\le 3$. We provide the full dataset of decays to the five 2s$^2$2p$^2$ ground configuration states $^3$P$_{0,1,2}$, $^1$D$_2$, $^1$S$_0$. This is the first complete set of data for transitions from $n\ge 5$. We compare oscillator strengths and transition probabilities with the few previously calculated values for such transitions, finding generally good agreement (within 10%) with the exception of values recently recommended by NIST, where significant discrepancies are found. We then calculate spectral line intensities originating from the Rydberg states using typical chromospheric conditions and assuming LTE, and compare them with well-calibrated SOHO SUMER UV spectra of the quiet Sun. The relative intensities of the Rydberg series are in excellent agreement with observation, which provides firm evidence for the identifications and blends of nearly 200 UV lines. Such comparison also resulted in a large number of new identifications of C I lines in the spectra. We also estimate optical depth effects and find that these can account for much of the absorption noted in the observations. The atomic data can be applied to model a wide range of solar and astrophysical observations.

Tidal disruption events (TDEs) are exotic transients that can lead to temporary super-Eddington accretion onto a supermassive black hole. Such accretion mode is naturally expected to result in powerful outflows of ionized matter. However, to date such an outflow has only been directly detected in the X-ray band in a single TDE, ASASSN-14li. This outflow has a low velocity of just a few 100 km/s, although there is also evidence for a second, ultra-fast phase. Here we present the detection of a low-velocity outflow in a second TDE, ASASSN-20qc. The high-resolution X-ray spectrum reveals an array of narrow absorption lines, each blueshifted by a few 100 km/s, which cannot be described by a single photo-ionization phase. For the first time, we confirm the multiphase nature of a TDE outflow, with at least two phases and two distinct velocity components. One highly ionized phase is outflowing at $910^{+90}_{-80}$ km/s, while a lower ionization component is blueshifted by $400_{-120}^{+100}$ km/s. We perform time-resolved analysis of the X-ray spectrum and detect that, surprisingly, the mildly ionized absorber strongly varies in ionization parameter over the course of a single 60 ks observation, indicating that its distance from the black hole may be as low as 400 gravitational radii. We discuss these findings in the context of TDEs and compare this newly detected outflow with that of ASASSN-14li.

In order to study transient phenomena in the Universe, existing and forthcoming imaging surveys are covering wide areas of sky repeatedly over time, with a range of cadences, point spread functions, and depths. We describe here a framework that allows an efficient search for different types of time-varying astrophysical phenomena in current and future, large data repositories. We first present a methodology to generate and store key survey parameters that enable researchers to determine if a survey, or a combination of surveys, allows specific time-variable astrophysical phenomena to be discovered. To facilitate further exploration of sources in regions of interest, we then generate a few sample metrics that capture the essential brightness characteristics of a sky pixel at a specific wavelength. Together, we refer to these as "annotated coadds". The techniques presented here for WISE/NEOWISE-R data are sensitive to 10 percent brightness variations at around 12th Vega magnitude at 4.5 microns wavelength. Application of the technique to ZTF data also enabled the detection of 0.5 mag variability at 20 AB mag in the r-band. We demonstrate the capabilities of these metrics for different classes of sources: high proper-motion stars, periodic variable stars, and supernovae, and find that each metric has its advantages depending on the nature of variability. We also present a data structure which will ease the search for temporally varying phenomena in future surveys.

Recent astronomical observations have shown that interstellar complex organic molecules (COMs) exist even in cold environments ($\sim$10 K), while various interstellar COMs have conventionally been detected in the hot gas ($\gtrsim$ 100 K) in the vicinity of high-mass and low-mass protostars. However, the formation pathway of each interstellar COM remains largely unclear. In this work, we demonstrate that an automated reaction path search based on transition state theory, which does not require predetermined pathways, is helpful for investigating the formation pathways of interstellar COMs in the gas phase. The exhaustive search within electronic ground states helps elucidate the complex chemical formation pathways of COMs at low temperatures. Here we examine the formation pathways of dimethyl ether (CH$_3$OCH$_3$) and methyl formate (HCOOCH$_3$), which are often detected in the cold and hot gas of star-forming regions. We have identified a barrierless and exothermic formation path of CH$_3$OCH$_3$ by reaction between neutral species; CH$_3$O + CH$_3$ $\rightarrow$ H$_2$CO $\cdots$ CH$_4$ $\rightarrow$ CH$_3$OCH$_3$ is the most efficient path in the large chemical network constructed by our automated reaction path search and is comparable with previous studies. For HCOOCH$_3$, we obtain complex pathways initiated from reactions between neutral species; HCOO and CH$_3$ generate HCOOCH$_3$ and its isomers without external energy. However, we also identified the competing reaction branches producing CO$_2$ + CH$_4$ and CH$_3$COOH, which would be more efficient than the formation of HCOOCH$_3$. Then the gas-phase formation of HCOOCH$_3$ through reactions between neutral species would not be efficient compared to the CH3OCH$_3$ formation.

We studied the frequency and critical mass accretion rate of millihertz quasi-periodic oscillations (mHz QPOs) using a one-zone X-ray burst model. The surface gravity is specified by two kinds of equation of states: neutron star (NS) and strange star (SS). The base flux, $Q_{b}$, is set in the range of 0-2 MeV nucleon$^{-1}$. It is found that the frequency of mHz QPO is positively correlated to the surface gravity but negatively to the base heating. The helium mass fraction has a significant influence on the oscillation frequency and luminosity. The observed 7-9 mHz QPOs can be either explained by a heavy NS/light SS with a small base flux or a heavy SS with a large base flux. As base flux increases, the critical mass accretion rate for marginally stable burning is found to be lower. Meanwhile, the impact of metallicity on the properties of mHz QPOs was investigated using one-zone model. It shows that both the frequency and critical mass accretion rate decrease as metallicity increases. An accreted NS/SS with a higher base flux and metallicity, combined with a lower surface gravity and helium mass fraction, could be responsible for the observed critical mass accretion rate ($\dot{m}\simeq 0.3\dot{m}_{\rm Edd}$). The accreted fuel would be in stable burning if base flux is over than $\sim$2 MeV nucleon$^{-1}$. This finding suggests that the accreting NSs/SSs in low-mass X-ray binaries showing no type I X-ray bursts possibly have a strong base heating.

The IceCube Neutrino Observatory deployed 5160 digital optical modules (DOMs) on 86 cables, called strings, in a cubic kilometer of deep glacial ice below the geographic South Pole. These record the Cherenkov light of passing charged particles. Knowledge of the DOM positions is vital for event reconstruction. While vertical positions have been calibrated, previous in-situ geometry calibration methods have been unable to measure horizontal deviations from the surface positions, largely due to degeneracies with ice model uncertainties. Thus the lateral position of the surface position of each hole is to date in almost all cases used as the lateral position of all DOMs on a given string. With the recent advances in ice modeling, two new in-situ measurements have now been undertaken. Using a large sample of muon tracks, the individual positions of all DOMs on a small number of strings around the center of the detector have been fitted. Verifying the results against LED calibration data shows that the string-average corrections improve detector modeling. Directly fitting string-average geometry corrections for the full array using LED data agrees with the average corrections as derived from muons where available. Analyses are now ongoing to obtain per-DOM positions using both methods and in addition, methods are being developed to correct the recorded arrival times for the expected scattering delay, allowing for multilateration of the positions using nanosecond-precision propagation delays.

Recent puzzling observations such as the $H_o$ tension, large-scale anisotropies, and massive disk galaxies at high redshifts have been challenging the standard cosmological model. While one possible explanation is that the standard model is incomplete, other theories are based on the contention that the redshift model as a distance indicator might be biased. While these theories can explain the recent observations, they are challenged by the absence of a direct empirical reproducible observation that the redshift model can indeed be inconsistent. Here I describe a simple experiment that shows that the spectra of galaxies depend on their rotational velocity relative to the rotational velocity of the Milky Way. Moreover, it shows that the redshift of galaxies that rotate in the same direction relative to the Milky Way is significantly different from the redshift of galaxies that rotate in the opposite direction relative to the Milky Way (P$<0.006$). Three different datasets are used independently, each one was prepared in a different manner, all of them show similar redshift bias. A fourth dataset of galaxies from the Southern Galactic pole was also analyzed, and shows similar results. All four datasets are publicly available. While a maximum average $\Delta z$ of $\sim$0.012 observed with galaxies of relatively low redshift (z$<$0.25) might not seem dramatic, the bias is consistent, and can explain puzzling observations such as the $H_o$ tension.

In this study, we revisit 32 planetary systems around evolved stars observed within the framework of the Okayama Planet Search Program and its collaborative framework of the EAPS-Net to search for additional companions and investigate the properties of stars and giant planets in multiple-planet systems. With our latest radial velocities obtained from Okayama Astrophysical Observatory (OAO), we confirm an additional giant planet in the wide orbit of 75 Cet system ($P_{\rm{c}} = 2051.62_{-40.47}^{+45.98}\ \rm{d}$, $M_{\rm{c}}\sin i=0.912_{-0.090}^{+0.088}\ M_{\rm{J}}$, and $a_{\rm{c}}=3.929_{-0.058}^{+0.052}\ \rm{au}$), along with five stars exhibiting long-term radial velocity accelerations, which indicates massive companions in the wide orbits. We have also found that the radial velocity variations of several planet-harboring stars may indicate additional planet candidates, stellar activities, or other understudied sources. These stars include $\epsilon$ Tau, 11 Com, 24 Boo, 41 Lyn, 14 And, HD 32518, and $\omega$ Ser. We further constrain the orbital configuration of the HD 5608, HD 14067, HD 120084, and HD 175679 systems by combining radial velocities with astrometry, as their host central stars exhibit significant astrometric accelerations. For other systems, we simply refine their orbital parameters. Moreover, our study indicates that the OPSP planet-harboring stars are more metal-poor compared to the currently known planet-harboring stars, and this is likely due to the $B-V$ color upper limit at 1.0 for star selection in the beginning of the survey. Finally, by investigating the less-massive giant planets ($< 5 M_{\rm{J}}$) around currently known planet-harboring evolved stars, we have found that metallicity positively correlates with the multiplicity and total planet mass of the system, which can be evidence for the core-accretion planet formation model.

Magnetic helicity is an important concept in solar physics, with a number of theoretical statements pointing out the important role of magnetic helicity in solar flares and coronal mass ejections (CMEs). Here we construct a sample of 47 solar flares, which contains 18 no-CME-associated confined flares and 29 CME-associated eruptive flares. We calculate the change ratios of magnetic helicity and magnetic free energy before and after these 47 flares. Our calculations show that the change ratios of magnetic helicity and magnetic free energy show distinct different distributions in confined flares and eruptive flares. The median value of the change ratios of magnetic helicity in confined flares is $-0.8$%, while this number is $-14.5$% for eruptive flares. For the magnetic free energy, the median value of the change ratios is $-4.3$% for confined flares, whereas this number is $-14.6$% for eruptive flares. This statistical result, using observational data, is well consistent with the theoretical understandings that magnetic helicity is approximately conserved in the magnetic reconnection, as shown by confined flares, and the CMEs take away magnetic helicity from the corona, as shown by eruptive flares.

The leading theory for the origin of Jupiter Trojans (JTs) assumes that JTs were captured to their orbits near the Lagrangian points of Jupiter during the early reconfiguration of the giant planets. The natural source region for the majority of JTs would then be the population of planetesimals born in a massive trans-Neptunian disk. If true, JTs represent the most accessible stable population of small Solar System bodies that formed in the outer regions of the Solar System. For this work, we compiled photometric datasets for about 1000 JTs and applied the convex inversion technique in order to assess their shapes and spin states. We obtained full solutions for $79$ JTs, and partial solutions for an additional $31$ JTs. We found that the observed distribution of the pole obliquities of JTs is broadly consistent with expectations from the streaming instability, which is the leading mechanism for the formation of planetesimals in the trans-Neptunian disk. The observed JTs' pole distribution has a slightly smaller prograde vs. retrograde asymmetry (excess of obliquities $>130^\circ$) than what is expected from the existing streaming instability simulations. However, this discrepancy can be plausibly reconciled by the effects of the post-formation collisional activity. Our numerical simulations of the post-capture spin evolution indicate that the JTs' pole distribution is not significantly affected by dynamical processes such as the eccentricity excitation in resonances, close encounters with planets, or the effects of nongravitational forces. However, a few JTs exhibit large latitude variations of the rotation pole and may even temporarily transition between prograde- and retrograde-rotating categories.

Cold streams of gas with temperatures around $10^4 \, \rm K$ play a crucial role in the gas accretion on to high-redshift galaxies. The current resolution of cosmological simulations is insufficient to fully capture the stability and Ly$\alpha$ emission characteristics of cold stream accretion, underscoring the imperative need for conducting idealized high-resolution simulations. We investigate the impact of magnetic fields at various angles and anisotropic thermal conduction (TC) on the dynamics of radiatively cooling streams through a comprehensive suite of two-dimensional high-resolution simulations. An initially small magnetic field ($\sim 10^{-3} \, \rm \mu G$), oriented non-parallel to the stream, can grow significantly, providing stability against Kelvin-Helmholtz instabilities and reducing the Ly$\alpha$ emission by a factor of $<20$ compared to the hydrodynamics case. With TC, the stream evolution can be categorised into three regimes: (1) the Diffusing Stream regime, where the stream diffuses into the surrounding hot circumgalactic medium; (2) the Intermediate regime, where TC diffuses the mixing layer, resulting in enhanced stabilization and reduced emissions; (3) the Condensing Stream regime, where the impact of magnetic field and TC on the stream's emission and evolution becomes negligible. Extrapolating our findings to the cosmological context suggests that cold streams with a radius of $\leq 1 \rm \, \rm kpc$ may fuel galaxies with cold, metal-enriched, magnetized gas ($B \sim 0.1\text{--}1 \, \rm \mu G$) for a longer time, leading to a broad range of Ly$\alpha$ luminosity signatures of $\sim 10^{37}\text{--}10^{40}\, \rm \, erg \, s^{-1}$.

Context. Although more than one thousand sub-stellar companions have already been detected with the radial velocity (RV) method, many new companions remain to be detected in the public RV archives. Aims. We wish to use the archival data obtained with the ESO/HARPS spectrograph to search for sub-stellar companions. Methods. We use the astronomic acceleration measurements of stars obtained with the Hipparcos and Gaia satellites to identify anomalies that could be explained by the presence of a companion. Once hints for a companion are found, we combine the RV data with absolute astrometry and, when available, relative astrometry data, using a Markov Chain Monte Carlo (MCMC) algorithm to determine the orbital parameters and mass of the companion. Results. We find and characterize three new brown dwarfs (GJ660.1 C, HD73256 B, and HD165131 B) and six new planets (HD75302 b, HD108202 b, HD135625 b, HD185283 b, HIP10337 b, and HIP54597 b) with separations between 1 and 6 au and masses between 0.6 and 100 MJup. We also constrain the orbital inclination of ten known sub-stellar companions and determine their true mass. Finally, we identify twelve new stellar companions. This shows that the analysis of proper motion anomalies allows for optimizing the RV search for sub-stellar companions and their characterization.

We present the results of a continuum reverberation mapping study of the radio-quiet Seyfert 1 galaxy IRAS 09149-6206. The analysis was performed using X-ray, UV and optical observations made with the {\em Swift} telescope between January and December 2017. The time delays between different light curves were measured using three different algorithms: PyI$^2$CCF, PyROA and JAVELIN. Our results show that the time delays increase with wavelength after $\tau\propto \lambda^{4/3}$, as predicted for a geometrically thin and optically thick accretion disc, but only after accounting for significant diffuse continuum emission from the broad line region. However, the measured size of the accretion disc can be up to five times larger than that predicted by standard theory. To our surprise, the strong increase in soft X-ray fluxes is delayed by about 15 days compared to the optical UV fluctuations, which challenges the prediction of the lamp-post model. Our analysis of the X-ray variability reveals the presence of a non-variable spectral component at 0.3-6.0 keV along with variable excess emission at 2.0-3.0 keV, which could be partly related to relativistic reflection in the inner region of the accretion disc. IRAS 09149-6206 joins the list of objects for which the traditional lamp-post model cannot explain the observed time delays. A scenario that incorporates other geometric considerations into the lamp-post model, e.g. an extended corona along a scattering source, might be better suited to explain the observed long time delays

We report elastic and inelastic cross sections for fast superthermal $^{12}$C($^3P$) and $^{13}$C($^3P$) atoms scattering on $^{12}$CO$_2$. The cross sections were computed using quantum-mechanical rotationally close-coupling formalism with the electronic interaction described by a newly constructed potential energy surface correlating to the lowest energy asymptote of the complex. State-to-state cross sections, differential cross sections, and derived transport properties of interest for energy relaxation are also reported. The computed elastic cross sections are strongly anisotropic, show significant energy dependence, and differ by up to 2% between the two isotopes of carbon.

CORSIKA up to version 7 has been the most-used Monte Carlo code for simulating extensive air showers for more than 20 years. Due to its monolithic, Fortran-based software design and hand-optimized code, however, it has become difficult to maintain, adapt to new computing paradigms and extend for more complex simulation needs. These limitations led to the CORSIKA 8 project, which constitutes a complete rewrite of the CORSIKA 7 core functionality in a modern, modular C++ framework. CORSIKA 8 has now reached a state that we consider "physics-complete" and a stability that already allows experts to engage in development for specific applications. It already supports the treatment of hadronic interactions with Sibyll 2.3d, QGSJet-II.04, EPOS-LHC and Pythia 8.3 and the treatment of the electromagnetic cascade with PROPOSAL 7.6.2. Particular highlights are the support for multiple interaction media, including cross-media particle showers, and an advanced calculation of the radio emission from particle showers. In this contribution, we discuss the design principles of CORSIKA 8, give an overview of the functionality implemented to date, the validation of its simulation results, and the plans for its further development.

The energy balance in the corona of the Sun is the key to the long-standing coronal heating dilemma, which could be potentially revealed by observational studies of decayless kink oscillations of coronal plasma loops. A bundle of very long off-limb coronal loops with the length of $736\pm80$ Mm and a lifetime of about 2 days are found to exhibit decayless kink oscillations. The oscillations were observed for several hours. The oscillation amplitude was measured at 0.3-0.5 Mm, and the period at 28-33 min. The existence of 30-min periodicity of decayless kink oscillations indicates that the mechanism compensating the wave damping is still valid in such a massive plasma structure. It provides important evidence for the non-resonant origin of decayless kink oscillations with 2-6min periods, i.e., the lack of their link with the leakage of photospheric and chromospheric oscillations into the corona and the likely role of the broadband energy sources. Magnetohydrodynamic seismology based on the reported detection of the kink oscillation, with the assistance of the differential emission measure analysis and a background coronal model provides us with a comprehensive set of plasma and magnetic field diagnostics, which is of interest as input parameters of space weather models.

Absorption and emission lines in the optical spectrum are typically used to investigate the presence of large-scale environments in active galactic nuclei (AGNs). BL Lac objects - which are a category of AGNs with the relativistic jet pointing directly to the observer - are supposed to represent a late evolution stage of AGNs. Their large-scale structures are probably poorer of material, which is distributed with lower densities throughout the circumnuclear environment. Their accretion disk is weak and weakly reprocessed, making the non-thermal continuum of the relativistic jet dominate their optical spectrum and preventing us from identifying the thermal emission of the photon fields produced by such large-scale structures. However, these photon fields may still exist and eventually interact with the gamma rays traveling in the blazar jet via gamma-gamma pair production, producing observable effects such as absorption features in their spectral energy distribution. Interestingly, the same photon field might also lead to the production of high-energy neutrinos, acting as targets for proton-photon interactions. In this contribution, we present the results of a set of simulations over a wide parameter space describing both the blazar jet and the photon field properties. We discuss the most effective conditions that may produce fluxes of neutrinos compatible with the sensitivities of the current and the next generation of neutrino detectors. We will also discuss how the possible neutrino flux would be related to the properties of the large-scale structures investigated indirectly through the analysis of the gamma-ray spectrum of the BL Lac object.

Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequent potential prebiotic connection to solar-like planetary systems. Recent surveys have reported an increasing number of hot corino detections in Class 0/I protostars; however, the relationships between their physical properties and the hot-corino signatures remain elusive. In this study, our objective is to establish a general picture of the detectability of the hot corinos by identifying the origin of the hot-corino signatures in the sample of young stellar objects (YSOs) obtained from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project. We apply spectral energy distribution (SED) modeling to our sample and identify the physical parameters of the modeled YSOs directly, linking the detection of hot-corino signatures to the envelope properties of the YSOs. Imaging simulations of the methanol emission further support this scenario. We, therefore, posit that the observed COM emission originates from the warm inner envelopes of the sample YSOs, based on both the warm region size and the envelope density profile. The former is governed by the source luminosity and is additionally affected by the disk and cavity properties, while the latter is related to the evolutionary stages. This scenario provides a framework for detecting hot-corino signatures toward luminous Class 0 YSOs, with fewer detections observed toward similarly luminous Class I sources.

Gravitational wave (GW) astronomy is witnessing a transformative shift from terrestrial to space-based detection, with missions like Taiji at the forefront. While the transition brings unprecedented opportunities to explore massive black hole binaries (MBHBs), it also imposes complex challenges in data analysis, particularly in parameter estimation amidst confusion noise. Addressing this gap, we utilize scalable Normalizing Flow models to achieve rapid and accurate inference within the Taiji environment. Innovatively, our approach simplifies the data's complexity, employs a transformation mapping to overcome the year-period time-dependent response function, and unveils additional multimodality in the arrival time parameter. Our method estimates MBHBs several orders of magnitude faster than conventional techniques, maintaining high accuracy even in complex backgrounds. These findings significantly enhance the efficiency of GW data analysis, paving the way for rapid detection and alerting systems and enriching our ability to explore the universe through space-based GW observation.

We constrain the $\Lambda$CDM cosmological parameter $\sigma_{8}$ by applying the extreme value statistics for galaxy cluster mass on the AMICO KiDS-DR3 catalog. We sample the posterior distribution of the parameters by considering the likelihood of observing the largest cluster mass value in a sample of $N_{\textrm{obs}} = 3644$ clusters with intrinsic richness $\lambda^{*} > 20$ in the redshift range $z\in[0.10, 0.60]$. We obtain $\sigma_{8}=0.90_{-0.18}^{+0.20}$, consistent within $1\sigma$ with the measurements obtained by the Planck collaboration and with previous results from cluster cosmology exploiting AMICO KiDS-DR3. The constraints could improve by applying this method to forthcoming missions, such as $\textit{Euclid}$ and LSST, which are expected to deliver thousands of distant and massive clusters.

Recent millimeter/sub-millimeter facilities have revealed the physical properties of filamentary molecular clouds in relation to high-mass star formation. A uniform survey of the nearest, face-on star-forming galaxy, the Large Magellanic Cloud (LMC), complements the Galactic knowledge. We present ALMA survey data with a spatial resolution of $\sim$0.1 pc in the 0.87 mm continuum and HCO$^{+}$(4-3) emission toward 30 protostellar objects with luminosities of 10$^4$-10$^{5.5}$ $L_{\odot}$ in the LMC. The spatial distributions of the HCO$^{+}$(4-3) line and thermal dust emission are well correlated, indicating that the line effectively traces dense, filamentary gas with an H$_2$ volume density of $\gtrsim$10$^5$ cm$^{-3}$ and a line mass of $\sim$10$^3$-10$^{4}$ $M_{\odot}$ pc$^{-1}$. Furthermore, we obtain an increase in the velocity linewidths of filamentary clouds, which follows a power-law dependence on their H$_2$ column densities with an exponent of $\sim$0.5. This trend is consistent with observations toward filamentary clouds in nearby star-forming regions withiin $ \lesssim$1 kpc from us and suggests enhanced internal turbulence within the filaments owing to surrounding gas accretion. Among the 30 sources, we find that 14 are associated with hub-filamentary structures, and these complex structures predominantly appear in protostellar luminosities exceeding $\sim$5 $\times$10$^4$ $L_{\odot}$. The hub-filament systems tend to appear in the latest stages of their natal cloud evolution, often linked to prominent H$\;${\sc ii} regions and numerous stellar clusters. Our preliminary statistics suggest that the massive filaments accompanied by hub-type complex features may be a necessary intermediate product in forming extremely luminous high-mass stellar systems capable of ultimately dispersing the parent cloud.

The latest Gaia data release in July 2022, DR3, added a number of important data products to those available in earlier releases, including radial velocity data, information on stellar multiplicity and XP spectra of a selected sample of stars. While the normal Gaia photometry (G, GBP and GRP bands) and astrometry can be used to identify white dwarfs with high confidence, it is much more difficult to parameterise the stars and determine the white dwarf spectral type from this information alone. The availability of the XP spectra and synthetic photometry presents an opportunity for more detailed spectral classification and measurement of effective temperature and surface gravity of Gaia white dwarfs. A magnitude limit of G < 17.6 was applied to the routine production of XP spectra for Gaia sources, which would have excluded most white dwarfs. We created a catalogue of 100,000 high-quality white dwarf identifications for which XP spectra were processed, with a magnitude limit of G < 20.5. Synthetic photometry was computed for all these stars, from the XP spectra, in Johnson, SDSS and J-PAS, published as the Gaia Synthetic Photometry Catalogue - White Dwarfs (GSPC-WD). We have now taken this catalogue and applied machine learning techniques to provide a classification of all the stars from the XP spectra. We have then applied an automated spectral fitting programme, with chi-squared minimisation, to measure their physical parameters (effective temperature and log g) from which we can estimate the white dwarf masses and radii. We present the results of this work, demonstrating the power of being able to classify and parameterise such a large sample of 100, 000 stars. We describe what we can learn about the white dwarf population from this data set. We also explore the uncertainties in the process and the limitations of the data set.

Solar, stellar and galactic large-scale magnetic fields are originated due to a combined action of non-uniform (differential) rotation and helical motions of plasma via mean-field dynamos. Usually, nonlinear mean-field dynamo theories take into account algebraic and dynamic quenching of alpha effect and algebraic quenching of turbulent magnetic diffusivity. However, these theories do not take into account a feedback of the mean magnetic field on the background turbulence (with a zero mean magnetic field). Our analysis using the budget equation for the total (kinetic plus magnetic) turbulent energy, which takes into account the feedback of the generated mean magnetic field on the background turbulence, has shown that a nonlinear dynamo number decreases with increase of the mean magnetic field for a forced turbulence, and a shear-produced turbulence and a convective turbulence. This implies that mean-field dynamo instability is always saturated.

Mergers of black holes and other compact objects produce gravitational waves which carry a part of the energy, momentum, and angular momentum of the system. Due to asymmetry in the gravitational wave emission, a recoil kick velocity is imparted to the merger remnant. It has been conjectured that a significant fraction of the mergers detected so far reside in globular clusters. We explore the scenario where the merger remnant in a globular cluster is moving at a significant speed with respect to the binary that underwent merger. We study this in the situation when the kick velocity is higher than the escape velocity in the case of globular clusters assuming a Plummer density profile for the cluster. We study the evolution of the system to study the outcome: whether dynamical friction can trap the black hole within the globular cluster, whether the black hole escapes the globular cluster but ends up in the bulge, and lastly, whether the black halo becomes a halo object. We present results for an analysis based on orbital parameters of ten globular clusters using data from GAIA EDR3. We find that if the kick velocity is smaller than $120$ km/s then a majority of remnant black holes end up in the bulge. Note that our results in terms of where compact objects launched from a globular cluster end up are applicable to any mechanism, e.g., a compact object ejected due to three-body interactions.

Combining the {\sc Cloudy} photoionization code with updated stellar population synthesis results, we simultaneously model the MIR $\neiii/\neii$ vs. $\oiv/\neiii$, the MIR-FIR $\neiii/\neii$ vs. $\oiv/\oiii$ and the classical BPT diagnostic diagrams. We focus on the properties of optically classified \hii\,galaxies that lie in the normal star forming zone in the MIR diagnostic diagram. We find that a small fraction of our models lie in this zone, but most of them correspond to the lowest explored metallicity, \zstar\,=\,0.0002, at age $\sim1$ Gyr. This value of \zstar\,is, by far, lower than the values derived for these galaxies from optical emission lines, suggesting that the far-UV emission produced by post-AGB stars (a.k.a. HOLMES, hot low-mass evolved stars) is NOT the source of ionization. Instead, shock models can easily reproduce this part of the MIR diagram. We suggest that it is likely that some of these galaxies have been misclassified and that in them, shocks, produced by a weak AGN-outflow, could be an important source of ionizaton. Using a subset of our models, we derive a new demarcation line for the maximal contribution of retired galaxies in the BPT diagram. This demarcation line allows for a larger contamination from the neighbouring AGN-dominated region. Considering the importance of disentangling the different ionising mechanisms in weak or deeply obscured systems, new observational efforts to classify galaxies both in the optical and IR are required to better constrain this kind of models and understand their evolutionary paths.

The formation of galaxies by gradual hierarchical co-assembly of baryons and cold dark matter halos is a fundamental paradigm underpinning modern astrophysics. A key test of this paradigm is via the observations of massive galaxies at early times as the evolution of the masses and abundances of dark matter halos is straight forward to simulate and massive halos should contain the universal cosmic baryon fraction at high redshift. Extremely massive quiescent galaxies > $10^{11}$ M$_\odot$ have now been observed as early as 1-2 billions years after the Big Bang producing tension with theoretical models and driving significant revisions. Typical spectroscopic ages of these objects are 300-500 Myr. Here we report on the spectroscopic observations with the James Webb Space Telescope of one of these objects that is quite different from the rest; selected by it having much redder colours. We see spectral features typical of much older stellar populations and detailed modeling shows that they formed at least 1.5 billion years earlier in time $z \gtrsim 11$ in a rapid star formation event. Dark matter halos massive enough to host these ancestors ought not to have assembled at this time. This observation may point to a significant gap in our understanding of early stellar populations, galaxy formation and/or the nature of dark matter.

An edge-on debris disk was detected in 2015 around the young, nearby A0V star HD 110058. The disk showed features resembling those seen in the disk of beta Pictoris that could indicate the presence of a perturbing planetary-mass companion in the system. We investigated new and archival scattered light images of the disk in order to characterise its morphology and spectrum. In particular, we analysed the disk's warp to constrain the properties of possible planetary perturbers. Our work uses data from two VLT/SPHERE observations and archival data from HST/STIS. We measured the morphology of the disk by analysing vertical profiles along the length of the disk to extract the centroid spine position and vertical height. We extracted the surface brightness and reflectance spectrum of the disk. We detect the disk between 20 au (with SPHERE) and 150 au (with STIS), at a position angle of 159.6$^\circ\pm$0.6$^\circ$. Analysis of the spine shows an asymmetry between the two sides of the disk, with a 3.4$^\circ\pm$0.9$^\circ$ warp between ~20 au and 60 au. The disk is marginally vertically resolved in scattered light, with a vertical aspect ratio of 9.3$\pm$0.7% at 45 au. The extracted reflectance spectrum is featureless, flat between 0.95 micron and 1.1 micron, and red from 1.1 micron to 1.65 micron. The outer parts of the disk are also asymmetric with a tilt between the two sides compatible with a disk made of forward-scattering particles and seen not perfectly edge-on, suggesting an inclination of <84$^\circ$. The presence of an undetected planetary-mass companion on an inclined orbit with respect to the disk could explain the warp. The misalignment of the inner parts of the disk with respect to the outer disk suggests a warp that has not yet propagated to the outer parts of the disk, favouring the scenario of an inner perturber as the origin of the warp.

The absorption by gas toward background continuum sources informs us about the cosmic density of gas components as well as the hosts responsible for the absorption (galaxies, clusters, cosmic filaments). Cosmic absorption line distributions are distorted near the detection threshold (S/N $\approx 3$) due to true lines being scattered to lower S/N and false detections occurring at the same S/N. We simulate absorption line distributions in the presence of noise and consider two models for recovery: a parametric fitting of the noise plus a cut-off power law absorption line distribution; a non-parametric fit where the negative absorption line distribution (emission lines) is subtracted from the positive S/N absorption line distribution (flip and subtract). We show that both approaches work equally well and can use data where S/N$\gtrsim$3 to constrain the fit. For an input of about 100 absorption line systems, the number of systems is recovered to $\approx$14%. This investigation examined the O VII X-ray absorption line distribution, but the approach should be broadly applicable for statistically well-behaved data.

High-precision radial velocity (RV) measurements are crucial for exoplanet detection and characterisation. Efforts to achieve ~10 cm/s precision have been made over the recent decades, with significant advancements in instrumentation, data reduction techniques, and statistical inference methods. However, despite these efforts, RV precision is currently limited to ~50 cm/s. This value exceeds state-of-the-art spectrographs' expected instrumental noise floor and is mainly attributed to RV signals induced by stellar variability. In this work, we propose a factorisation method to overcome this limitation. The factorisation is particularly suitable for controlling the effect of localised changes in the stellar emission profile, assuming some smooth function of a few astrophysical parameters governs them. We use short-time Fourier transforms (STFT) to infer the RV in a procedure equivalent to least-squares minimisation in the wavelength domain and demonstrate the effectiveness of our method in treating arbitrary temperature fluctuations on the star's surface. The proposed prescription can be naturally generalised to account for other effects, either intrinsic to the star, such as magnetic fields, or extrinsic to it, such as telluric contamination. As a proof-of-concept, we empirically derive a set of factorisation terms describing the Solar centre-to-limb variation and apply them to a set of realistic SOAP-GPU spectral simulations. We discuss the method's capability to mitigate variability-induced RV signals and its potential extensions to serve as a tomographic tool.

Recently released data from pulsar timing array (PTA) collaborations provide strong evidence for a stochastic signal consistent with a gravitational-wave background, potentially originating from scalar-induced gravitational waves (SIGWs). However, in order to determine whether the SIGWs with a specific power spectrum of curvature perturbations can account for the PTA signal, one needs to estimate the energy density of the SIGWs, which can be computationally expensive. In this paper, we use a model-independent approach to reconstruct the primordial curvature power spectrum using a free spectrum cross over from $10^{1}\,\mathrm{Mpc}^{-1}$ to $10^{20}\,\mathrm{Mpc}^{-1}$ with NANOGrav 15-yrs data set. Our results can simplify the task of assessing whether a given primordial curvature power spectrum can adequately explain the observed PTA signal without calculating the energy density of SIGWs.

Helium white dwarfs (HeWDs) are thought to form from low-mass red giant stars experiencing binary interaction. Because the helium core mass of a red giant star is closely related to the stellar radius, there exists well-known relation between the orbital period ($P_{\rm orb}$) and the mass ($M_{\rm WD}$) of the HeWDs, which is almost independent of the type of the companion star. Traditional derivation of the $M_{\rm WD}$-$P_{\rm orb}$ relation generally neglected the effect of wind mass loss from the red giants, while observations show that wind mass loss from red giants in binary systems is systematically higher than that from isolated stars. In this work, we calculate binary evolution with tidally enhanced stellar wind (TEW) and find that it causes significantly scatter of the traditional $M_{\rm WD}$-$P_{\rm orb}$ relation. The TEW can prevent the red giants from overflowing their Roche lobes and slow down the growth of the helium core, leaving a lower-mass HeWD for given orbital period. This scenario may account for some of the HeWD binaries that deviate from the traditional $M_{\rm WD}$-$P_{\rm orb}$ relation. However, we point out that observations of more HeWD binaries in wide orbits are needed to test the TEW model and to constrain the enhanced wind factor.

Protoplanets growing within the protoplanetary disk by pebble accretion acquire hydrostatic gas envelopes. Due to accretion heating, the temperature in these envelopes can become high enough to sublimate refractory minerals which are the major components of the accreted pebbles. Here we study the sublimation of different mineral species and determine whether sublimation plays a role during the growth by pebble accretion. For each snapshot in the growth process, we calculate the envelope structure and sublimation temperature of a set of mineral species representing different levels of volatility. Sublimation lines are determined using and equilibrium scheme for the chemical reactions responsible for destruction and formation of the relevant minerals. We find that the envelope of the growing planet reaches temperatures high enough to sublimate all considered mineral species when the mass is larger than 0.4 Earth masses. The sublimation lines are located within the gravitionally bound envelope of the planet. We make a detailed analysis of the sublimation of FeS at around 720 K, beyond which the mineral is attacked by H2 to form gaseous H2S and solid Fe. We calculate the sulfur concentration in the planet under the assumption that all sulfur released as H2S is lost from the planet by diffusion back to the protoplanetary disk. Our calculated values are in good agreement with the slightly depleted sulfur abundance of Mars, while the model overpredicts the extensive sulfur depletion of Earth by a factor of approximately 2. We show that a collision with a sulfur-rich body akin to Mars in the moon-forming impact lifts the Earth's sulfur abundance to approximately 10% of the solar value for all impactor masses above 0.05 Earth masses.

The Telescope Array (TA) of central Utah was designed to detect ultra-high-energy cosmic rays (UHECRs) and is the largest of its kind in the Northern hemisphere. Its capabilities, however, are not limited to extra-terrestrial sources. Scintillation detectors (SDs) in the array are designed to measure energy deposit from charged cosmic ray secondaries, but have recently caught bursts of electromagnetic radiation that do not match the typical signature of cosmic ray air showers. After investigation, the bursts were tied to individual lightning strikes. In an effort to better understand the phenomenon, Langmuir Laboratory for Atmospheric Research at New Mexico Tech provided specialized lightning detectors across the array, eventually confirming the events as downward terrestrial gamma-ray flashes (TGFs) produced in the first few microseconds of lightning flashes. After 20 identified TGFs and 2 publications, the lightning instrumentation at Telescope Array was upgraded in the summer of 2018 with the addition of a broadband interferometer (INTF) for high-resolution lightning mapping. This unique variety of lightning detectors has become one of the leading studies of downward TGFs. This dissertation is focused on the application of this method and resultson four events from late 2018. The individual TGFs lasted <10 us and likely consisted of >10^12 gamma-rays, with evidence of some energies >2.6 MeV. I determined TGF source times, plan locations, and altitudes with average uncertainties of 0.6 us, 140 m, and 25 m, respectively. This high resolution showed that TGFs in all four of these events occured during strong initial breakdown pulses and was driven by streamer-based fast negative breakdown in the first couple milliseconds of negative intracloud and cloud-to-ground lightning flashes.

The Rocky Planet Search (RPS) program is dedicated to a blind radial velocity (RV) search of planets around bright stars in the Northern hemisphere, using the high-resolution echelle spectrograph HARPS-N installed on the Telescopio Nazionale Galileo (TNG). The goal of this work is to revise and update the properties of three planetary systems by analysing the HARPS-N data with state-of-the-art stellar activity mitigation tools. The stars considered are HD 99492 (83Leo B), HD 147379 (Gl617 A) and HD 190007. We employ a systematic process of data modelling, that we selected from the comparison of different approaches. We use YARARA to remove instrumental systematics from the RV, and then use SPLEAF to further mitigate the stellar noise with a multidimensional correlated noise model. We also search for transit features in the Transiting Exoplanets Survey Satellite (TESS) data of these stars. We report on the discovery of a new planet around HD 99492, namely HD 99492 c, with an orbital period of 95.2 days and a minimum mass of msin i = 17.9 M_Earth, and refine the parameters of HD 99492 b. We also update and refine the Keplerian solutions for the planets around HD 147379 and HD 190007, but do not detect additional planetary signals. We discard the transiting geometry for the planets, but stress that TESS did not exhaustively cover all the orbital phases. The addition of the HARPS-N data, and the use of advanced data analysis tools, has allowed us to present a more precise view of these three planetary systems. It demonstrates once again the importance of long observational efforts such as the RPS program. Added to the RV exoplanet sample, these planets populate two apparently distinct populations revealed by a bimodality in the planets minimum mass distribution. The separation is located between 30 and 50 M_Earth.

This paper presents an intramethod ensemble for coronal hole (CH) detection based on the Active Contours Without Edges (ACWE) segmentation algorithm. The purpose of this ensemble is to develop a confidence map that defines, for all on disk regions of a Solar extreme ultraviolet (EUV) image, the likelihood that each region belongs to a CH based on that region's proximity to, and homogeneity with, the core of identified CH regions. CHs are regions of open magnetic field lines, resulting in high speed solar wind. Accurate detection of CHs is vital for space weather prediction. By relying on region homogeneity, and not intensity (which can vary due to various factors including line of sight changes and stray light from nearby bright regions), to define the final confidence of any given region, this ensemble is able to provide robust, consistent delineations of the CH regions. Using the metrics of global consistency error (GCE), local consistency error (LCE), intersection over union (IOU), and the structural similarity index measure (SSIM), the method is shown to be robust to different spatial resolutions and different intensity resolutions. Furthermore, using the same metrics, the method is shown to be robust across short timescales, indicating self-consistent segmentations. Finally, the accuracy of the segmentations and confidence maps are validated by considering the skewness (i.e., unipolarity) of the underlying magnetic field.

The Jovian Infrared Auroral Mapper (JIRAM) instrument aboard Juno has allowed clear, high-resolution imaging of Io's polar volcanoes. We have used data from JIRAM's M-band (4.78 micron) imager from eleven Juno orbits to construct a global map of volcanic flux. This map provides insight into the spatial distribution of volcanoes and the ways in which high- and low-latitude volcanoes differ. Using spherical harmonic analysis, we have quantitatively compared our volcanic flux map to the surface heat flow distribution expected by modeling data of Io's tidal heat deposition (de Kleer et al. 2019). Systems of bright volcanoes were confirmed at high latitudes. Our study finds that both poles are more active than previous studies have suggested, although the south pole was viewed too infrequently to establish reliable long-term trends. While none of the tidal heat flow models match well, the asthenospheric heating model agrees best with the observed volcanic flux.

We analyzed changes in the height of the coronal hard X-ray (HXR) source for flares SOL2013-05-13T01:50 and SOL2013-05-13T15:51. Analysis of the Reuven Ramaty High Energy Solar Spectroscopic Imager data revealed the downward motion of the HXR source and the separation of the sources by energy and height. In the early stages of the flares, a negative correlation was found between the HXR source area in the corona and HXR flux. For the SOL2013-05-13T15:51 event, an increasing trend in the time delay spectra at the footpoints was obtained. For both events, the spectra of the time delays in the coronal HXR source showed a decreasing trend across the energies in certain flare phases. To interpret the observed phenomena, we considered a flare model of collapsing traps and calculated the distribution functions of accelerated electrons along the magnetic loop using a nonstationary relativistic kinetic equation. This approach considers betatron and Fermi first-order acceleration mechanisms. The increasing trend of the time delay spectra at the footpoints was explained by the high mirror ratio in the magnetic loop and betatron acceleration mechanism. The observed features in the spatial and temporal behavior of the HXR sources, such as the negative correlation between the HXR source area and HXR flux, can be interpreted by the collapsing trap model.

Ultraviolet observations of Ultra-hot Jupiters (UHJs), exoplanets with temperatures over 2000\,K, provide us with an opportunity to investigate if and how atmospheric escape shapes their upper atmosphere. Near-ultraviolet transit spectroscopy offers a unique tool to study this process owing to the presence of strong metal lines and a bright photospheric continuum as the light source against which the absorbing gas is observed. WASP-189b is one of the hottest planets discovered to date, with a day-side temperature of about 3400\,K orbiting a bright A-type star. We present the first near-ultraviolet observations of WASP-189b, acquired with the Colorado Ultraviolet Transit Experiment ($CUTE$). $CUTE$ is a 6U NASA-funded ultraviolet spectroscopy mission, dedicated to monitoring short-period transiting planets. WASP-189b was one of the $CUTE$ early science targets and was observed during three consecutive transits in March 2022. We present an analysis of the $CUTE$ observations and results demonstrating near-ultraviolet (2500--3300~\AA) broadband transit depth ($1.08^{+0.08}_{-0.08}\%$) of about twice the visual transit depth indicating that the planet has an extended, hot upper atmosphere with a temperature of about 15000\,K and a moderate mass loss rate of about \SI{4e8}{\kg\per\second}. We observe absorption by Mg{\sc ii} lines ($R_p/R_s$ of $0.212^{+0.038}_{-0.061}$) beyond the Roche lobe at $>$4$\sigma$ significance in the transmission spectrum at a resolution of 10~\AA, while at lower resolution (100~\AA), we observe a quasi-continuous absorption signal consistent with a "forest" of low-ionization metal absorption dominated by Fe{\sc ii}. The results suggest an upper atmospheric temperature ($\sim15000$\,K), higher than that predicted by current state-of-the-art hydrodynamic models.

Large-scale international scientific collaborations are increasingly common in the field of STEM (Science, Technology, Engineering, and Mathematics). However, little is known about the well-being of the members participating in these `big science' collaborations, which can present unique challenges due to the scale of their work. We conducted a survey among members of three large, international collaborations in the field of gravitational-wave astrophysics in the summer of 2021. Our objective was to investigate how career stage, job insecurity and minority status are associated with reported levels of depressive symptoms as well as the desire to leave academia. We found that early-career scientists and certain minoritized groups reported significantly higher levels of depressive symptoms compared to senior members or those who do not consider themselves as a member of minoritized groups. Furthermore, relatively young members, staff scientists/engineers, and those experiencing high levels of job insecurity and lack of recognition were more likely to frequently consider leaving academia. Our findings suggest that improving recognition for personal contributions to collaborative work and providing clearer job perspectives could be two key factors in enhancing the well-being of young scientists and reducing the potential outflow from academia.

We investigate the capture rate of the cosmic neutrino background on tritium within the Standard Model, extended to incorporate three right-handed singlet neutrinos with explicit lepton-number violation. We consider a scenario where the $6 \times 6$ neutrino mixing matrix factorizes into three independent $2 \times 2$ pairs and analyze the states produced from weak interactions just before neutrino decoupling. Taking into account the unrestricted Majorana mass scale associated with lepton number violation, spanning from the Grand Unification scale to Planck-suppressed values, we observe a gradual transition in the capture rate from a purely Majorana neutrino to a purely (pseudo) Dirac neutrino. We demonstrate that the capture rate is modified if the lightest active neutrino is relativistic, and this can be used to constrain the tiniest value of mass-squared difference $\sim 10^{-35}\,{\rm eV}^2$, between the active-sterile pair, probed so far. Consequently, the cosmic neutrino capture rate could become a promising probe for discerning the underlying mechanism responsible for generating neutrino masses.

We analyse the results of direct numerical simulations of rotating convection in spherical shell geometries with stress-free boundary conditions, which develop strong zonal flows. Both the Ekman number and the Rayleigh number are varied. We find that the asymptotic theory for rapidly rotating convection can be used to predict the Ekman number dependence of each term in the governing equations, along with the convective flow speeds and the dominant length scales. Using a balance between the Reynolds stress and the viscous stress, together with the asymptotic scaling for the convective velocity, we derive an asymptotic prediction for the scaling behaviour of the zonal flow with respect to the Ekman number, which is supported by the numerical simulations. We do not find evidence of distinct asymptotic scalings for the buoyancy and viscous forces and, in agreement with previous results from asymptotic plane layer models, we find that the ratio of the viscous force to the buoyancy force increases with Rayleigh number. Thus, viscosity remains non-negligible and we do not observe a trend towards a diffusion-free scaling behaviour within the rapidly rotating regime.

Within the context of energy-momentum squared gravity (EMSG), where non-linear matter contributions appear in the gravitational action, we derive the modified TOV equations describing the hydrostatic equilibrium of charged compact stars. We adopt two different choices for the matter Lagrangian density ($\mathcal{L}_m= p$ versus $\mathcal{L}_m= -\rho$) and investigate the impact of each one on stellar structure. Furthermore, considering a charge profile where the electric charge density $\rho_{\rm ch}$ is proportional to the standard energy density $\rho$, we solve numerically the stellar structure equations in order to obtain the mass-radius diagrams for the MIT bag model equation of state (EoS). For $\mathcal{L}_m= p$ and given a specific value of $\beta$ (including the uncharged case when $\beta= 0$), the maximum-mass values increase (decrease) substantially as the gravity model parameter $\alpha$ becomes more negative (positive). However, for uncharged configurations and considering $\mathcal{L}_m= -\rho$, our numerical results reveal that when we increase $\alpha$ (from a negative value) the maximum mass first increases and after reaching a maximum value it starts to decrease. Remarkably, this makes it a less trivial behavior than that caused by the first choice when we take into account the presence of electric charge ($\beta \neq 0$).

There are two free coupling parameters $c_{13}$ and $c_{14}$ in the Einstein-\AE ther metric describing a non-rotating black hole. This metric is the Reissner-Nordstr\"{o}m black hole solution when $0\leq 2c_{13}<c_{14}<2$, but it is not for $0\leq c_{14}<2c_{13}<2$. When the black hole is immersed in an external asymptotically uniform magnetic field, the Hamiltonian system describing the motion of charged particles around the black hole is not integrable. However, the Hamiltonian allows for the construction of explicit symplectic integrators. The proposed fourth-order explicit symplectic scheme is used to investigate the dynamics of charged particles because it exhibits excellent long-term performance in conserving the Hamiltonian. No universal rule can be given to the dependence of regular and chaotic dynamics on varying one or two parameters $c_{13}$ and $c_{14}$ in the two cases of $0\leq 2c_{13}<c_{14}<2$ and $0\leq c_{14}<2c_{13}<2$. The distributions of order and chaos in the binary parameter space $(c_{13},c_{14})$ rely on different combinations of the other parameters and the initial conditions.

The strong coupling in the effective quark mass was usually taken as a constant in a quasiparticle model while it is, in fact, running with an energy scale. With a running coupling, however, the thermodynamic inconsistency problem appears in the conventional treatment. We show that the renormalization subtraction point should be taken as a function of the summation of the biquadratic chemical potentials if the quark's current masses vanish, in order to ensure full thermodynamic consistency. Taking the simplest form, we study the properties of up-down ($ud$) quark matter, and confirm that the revised quasiparticle model fulfills the quantitative criteria for thermodynamic consistency. Moreover, we find that the maximum mass of an $ud$ quark star can be larger than two times the solar mass, reaching up to $2.31M_{\odot}$, for reasonable model parameters. However, to further satisfy the upper limit of tidal deformability $\tilde{\Lambda}_{1.4}\leq 580$ observed in the event GW170817, the maximum mass of an $ud$ quark star can only be as large as $2.08M_{\odot}$, namely $M_{\text{max}}\lesssim2.08M_{\odot}$. In other words, our results indicate that the measured tidal deformability for event GW170817 places an upper bound on the maximum mass of $ud$ quark stars, but which does not rule out the possibility of the existence of quark stars composed of $ud$ quark matter, with a mass of about two times the solar mass.

We consider static and spherically symmetric wormhole solutions in extended metric-affine theories of gravity supposing that stability and traversability of these objects can be achieved by means of the geometric degrees of freedom. In particular, we consider $f(R)$ metric, $f(T)$ teleparallel, and $f(Q)$ symmetric teleparallel models where curvature, torsion, and non-metricity rule entirely the background geometry without invoking any exotic energy-momentum tensor as matter field source. Starting from the flaring out and null energy conditions, we gather together a series of constraints which allow us to state that stable and traversable wormholes can be derived in a purely geometric approach resorting to modified gravity theories with more degrees of freedom than general relativity.

In this work, we have studied the behavior of null geodesics within a rotating wormhole space-time in non-magnetized pressure-less plasma. By focusing on the dispersion relation of the plasma and disregarding its direct gravitational effects, we examine how light rays traverse in the mentioned space-time. A key highlight of the work is the necessity of a specific plasma distribution profile to establish a generalized Carter's constant, shedding light on the importance of this parameter. Furthermore, we have derived analytical formulas to distinguish the shadow boundary across various plasma profiles, uncovering a fascinating trend of diminishing shadow size as plasma density increases. Intriguingly, certain limits of the plasma parameters result in the complete disappearance of the shadow. When calculating the deflection angle by a wormhole in plasma space-time, we observe a distinct pattern: the angle decreases as the plasma parameter rises in non-homogeneous plasma space-time, diverging from the behavior observed in homogeneous plasma space-time. Also, leveraging observational data from M$87^{\ast}$, we establish constraints on the throat radius. Furthermore, minimum shadow diameters provide valuable constraints for the radial and latitudinal plasma parameters.

Atmospheric collisions can copiously produce dark sector particles in the invisible dark photon model, leading to detectable signals in underground neutrino detectors. We consider the dark photon model with the mass mixing mechanism and use the Super-K detector to detect the electron recoil events caused by the atmospherically produced dark sector particles within the model. We find that the combined data from four Super-K runs yield new leading constraints for the invisible dark photon in the mass range of $\sim(0.5-1.4)$ GeV, surpassing the constraints from NA64, BaBar, and searches for millicharged particles.