adsabs/SciX_UAT_keywords huggingface dataset:
Cosmic-Ray-driven Outflows from the Large Magellanic Cloud: Contributions to the LMC Filament

In this paper, we build from previous work and present simulations of recent (within the past Gyr), magnetized, cosmic-ray driven outflows from the Large Magellanic Cloud (LMC), including our first attempts to explicitly use the derived star formation history of the LMC to seed outflow generation. We run a parameter set of simulations for different LMC gas masses and cosmic-ray transport treatments, and we make preliminary comparisons to published outflow flux estimates, neutral and ionized hydrogen observations, and Faraday rotation measure maps. We additionally report on the gas mass that becomes unbound from the LMC disk and swept by ram pressure into the Trailing Magellanic Stream. We find that, even for our largest outburst, the mass contribution to the Stream is still quite small, as much of the outflow-turned-halo gas is shielded on the LMCs far-side due to the LMCs primarily face-on infall through the Milky Way halo over the past Gyr. On the LMC's near-side, past outflows have fought an uphill battle against ram pressure, with the near-side halo mass being at least a factor of a few smaller than that of the far-side. Absorption-line studies probing only the LMC foreground, then, may be severely underestimating the total mass of the LMC halo formed by outflows.

Keywords: large magellanic cloud; cosmic rays; galactic winds; magellanic stream; magnetic fields
Nonparametric Representation of Neutron Star Equation of State Using Variational Autoencoder

We introduce a new nonparametric representation of the neutron star (NS) equation of state (EOS) by using the variational autoencoder (VAE). As a deep neural network, the VAE is frequently used for dimensionality reduction since it can compress input data to a low-dimensional latent space using the encoder component and then reconstruct the data using the decoder component. Once a VAE is trained, one can take the decoder of the VAE as a generator. We employ 100,000 EOSs that are generated using the nonparametric representation method based on Han et al. as the training set and try different settings of the neural network, then we get an EOS generator (the trained VAE's decoder) with four parameters. We use the mass-tidal-deformability data of binary NS merger event GW170817, the mass-radius data of PSR J0030+0451, PSR J0740+6620, PSR J0437-4715, and 4U 1702-429, and the nuclear constraints to perform the Bayesian inference. The overall results of the analysis that includes all the observations are ${R}_{1.4}={12.59}_{-0.42}^{+0.36}\,\mathrm{km}$ , ${{\rm{\Lambda }}}_{1.4}={489}_{-110}^{+114}$ , and ${M}_{\max }={2.20}_{-0.19}^{+0.37}\,{M}_{\odot }$ (90% credible levels), where R 1.4/Λ1.4 are the radius/tidal deformability of a canonical 1.4 M ⊙ NS, and ${M}_{\max }$ is the maximum mass of a nonrotating NS. The results indicate that the implementation of these VAE techniques can obtain reasonable results, while accelerating calculation by a factor of ~3-10 or more, compared with the original method.

Keywords: neutron stars; nonparametric inference
High-resolution Chromospheric Observations of a Solar Minifilament: Formation and Destabilization

Using Hα line core and off-band imaging data from the New Vacuum Solar Telescope in China, we present a high-resolution observation on the entire life cycle of a solar minifilament from its birth to its final eruption. We find that the minifilament originates from a series of cascade-like reconfigurations of chromospheric fine structures. During which, owing to strong photospheric shearing and converging flows near its polarity inversion line, basic short chromospheric fibrils first slowly coalesce to elongated dark threads, and then further create a longer filament channel in a "head-to-tail" linkage scenario. In this course, obvious magnetic flux cancelation simultaneously proceeds below it, and further facilitates its destabilization. In its onset phase, clear clues indicate that the minifilament first starts to rise without brightening signals; instead, after a slow-to-fast acceleration, obvious runaway reconnection soon takes over its final jet-like eruption. Besides, off-band observations further reveal that the formed minifilament has a possible flux-rope configuration, and chromospheric upflows that detected in its early forming phase persistently supplies cool plasma into its channel. This observation is consistent with earlier observations and supports the view that both miniature and large-scale filaments may share analogous formation and destabilization mechanisms.

Keywords: solar activity; solar filaments; solar magnetic fields
On the Mass Distribution of the Intracluster Light in Galaxy Groups and Clusters

We take advantage of a semianalytic model with a state-of-art implementation of the formation of the intracluster light (ICL) to study the mass distribution of the ICL in galaxy groups and clusters, at different redshifts. We assume the ICL to follow a Navarro-Frenk-White (NFW) profile with a different concentration, linked to that of the dark matter by the relation cICL = γ cDM, where the parameter γ is set to reproduce the observed relation between the stellar mass in the brightest cluster galaxy (BCG) and ICL in the innermost 100 kpc and the halo mass (M*100 - M500) at z = 0. The model is then tested against several theoretical and observational results, from the present time to z ∼ 1.5. Our analysis shows that the fraction of stellar mass in the BCG and ICL within the innermost 100 kpc is an increasing function of redshift, parameter γ, and a decreasing function of the halo mass. The value of γ required to match the observed M*100 - M500 is γ = 3 at z = 0, but there are indications that it might be a function of redshift and halo mass. This result indicates that the distribution of the ICL is more concentrated than the dark matter one, but less concentrated than previously found by other studies. We suggest that a modified version of the NFW is a good description of the distribution of the diffuse light in groups and clusters, which makes the ICL a reliable tracer of the dark matter, in good agreement with recent observational findings.

Keywords: galaxy formation; galaxy evolution
Inner Planetary System Gap Complexity is a Predictor of Outer Giant Planets

The connection between inner small planets and outer giant planets is crucial to our understanding of planet formation across a wide range of orbital separations. While Kepler provided a plethora of compact multiplanet systems at short separations (≲1 au), relatively little is known about the occurrence of giant companions at larger separations and how they impact the architectures of the inner systems. Here, we use the catalog of systems from the Kepler Giant Planet Search to study how the architectures of the inner transiting planets correlate with the presence of outer giant planets. We find that for systems with at least three small transiting planets, the distribution of inner-system gap complexity ( ${ \mathcal C }$ ), a measure of the deviation from uniform spacings, appears to differ (p ≲ 0.02) between those with an outer giant planet ( $50{M}_{\oplus }\leqslant {M}_{p}\sin i\leqslant 13{M}_{\mathrm{Jup}}$ ) and those without any outer giants. All four inner systems (with three or more transiting planets) with outer giant(s) have a higher gap complexity ( ${ \mathcal C }\gt 0.32$ ) than 79% (19/24) of the inner systems without any outer giants (median ${ \mathcal C }\simeq 0.06$ ). This suggests that one can predict the occurrence of outer giant companions by selecting multitransiting systems with highly irregular spacings. We do not find any correlation between the outer giant occurrence and the size (similarity or ordering) patterns of the inner planets. The higher gap complexities of inner systems with an outer giant hints that massive external planets play an important role in the formation and/or disruption of the inner systems.

Keywords: exoplanet systems; exoplanet detection methods; exoplanet dynamics; exoplanet formation; exoplanets; extrasolar gaseous giant planets; extrasolar rocky planets; planetary system formation; radial velocity
Investigating the Relationship between (3200) Phaethon and (155140) 2005 UD through Telescopic and Laboratory Studies

The relationship between the near-Earth objects (3200) Phaethon and (155140) 2005 UD is unclear. While both are parents to meteor showers (the Geminids and Daytime Sextantids, respectively) and have similar visible-wavelength reflectance spectra and orbits, dynamical investigations have failed to find any likely method to link the two objects in the recent past. Here we present the first near-infrared reflectance spectrum of 2005 UD, which shows it to be consistently linear and red-sloped, unlike Phaethon's very blue and concave spectrum. Searching for a process that could alter some common starting material to both of these end states, we hypothesized that the two objects had been heated to different extents, motivated by their near-Sun orbits, the composition of Geminid meteoroids, and previous models of Phaethon's surface. We thus set about building a new laboratory apparatus to acquire reflectance spectra of meteoritic samples after heating to higher temperatures than available in the literature to test this hypothesis and were loaned a sample of the CI chondrite Orgueil from the Vatican Meteorite Collection for testing. We find that while Phaethon's spectrum shares many similarities with different CI chondrites, 2005 UD's does not. We thus conclude that the most likely relationship between the two objects is that their similar properties are only by coincidence as opposed to a parent-fragment scenario, though the ultimate test will be when JAXA's DESTINY+ mission visits one or both of the objects later this decade. We also discuss possible paths forward to understanding Phaethon's properties from dynamical and compositional grounds.

Keywords: asteroids; comets; meteor showers; near-earth objects; laboratory astrophysics
Searching for Radio Outflows from M31* with VLBI Observations

As one of the nearest and most dormant supermassive black holes (SMBHs), M31* provides a rare but promising opportunity for studying the physics of black hole accretion and feedback at the quiescent state. Previous Karl G. Jansky Very Large Array (VLA) observations with an arcsecond resolution have detected M31* as a compact radio source over centimeter wavelengths, but the steep radio spectrum suggests optically thin synchrotron radiation from an outflow driven by a hot accretion flow onto the SMBH. Aiming to probe the putative radio outflow, we conducted milliarcsecond-resolution very long baseline interferometric (VLBI) observations of M31* in 2016, primarily at 5 GHz and combining the Very Long Baseline Array, Tianma 65 m, and Shanghai 25 m radio telescopes. Despite the unprecedented simultaneous resolution and sensitivity achieved, no significant (≳3σ) signal is detected at the putative position of M31* given an rms level of 5.9 μJy beam-1, thus ruling out a pointlike source with a peak flux density comparable to that (~30 μJy beam-1) measured by the VLA observations taken in 2012. We disfavor the possibility that M31* has substantially faded since 2012, in view that a 2017 VLA observation successfully detected M31* at a historically high peak flux density (~75 μJy beam-1 at 6 GHz). Instead, the nondetection of the VLBI observations is best interpreted as the arcsecond-scale core being resolved out at the milliarcsecond scale, suggesting an intrinsic size of M31* at 5 GHz larger than ~300 times the Schwarzschild radius. Such extended radio emission may originate from a hot wind driven by the weakly accreting SMBH.

Keywords: low-luminosity active galactic nuclei; radio continuum emission; local group; andromeda galaxy
[O III] 5007 Å Emission Line Width as a Surrogate for σ ∗ in Type 1 AGNs?

We present a study of the relation between the [O III] 5007 Å emission line width (σ [OIII]) and stellar velocity dispersion (σ *), utilizing a sample of 740 type 1 active galactic nuclei (AGNs) with high-quality spectra at redshift z < 1.0. We find the broad correlation between the core component of the [O III] emission line width ( ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ ) and σ * with a scatter of 0.11 dex for the low redshift (z < 0.1) sample; for redshift (0.3 < z < 1.0) AGNs, the scatter is larger, being 0.16 dex. We also find that the Eddington ratio (L bol/L Edd) may play an important role in the discrepancies between ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ and σ *. As the L bol/L Edd increases, ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ tends to be larger than σ *. By classifying our local sample with different minor-to-major axis ratios, we find that σ * is larger than ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ for those edge-on spiral galaxies. In addition, we also find that the effects of outflow strength properties such as maximum outflow velocity ( ${V}_{\max }$ ) and the broader component of the [O III] emission line width and line shift (σ [OIII,out] and V [OIII,out]) may play a major role in the discrepancies between ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ and σ *. The discrepancies between ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ and σ * are larger when ${V}_{\max }$ , V [OIII,out], and σ [OIII,out] increase. Our results show that the outflow strengths may have significant effects on the differences between narrow-line region gas and stellar kinematics in AGNs. We suggest that caution should be taken when using ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ as a surrogate for σ *. In addition, the substitute of ${\sigma }_{[{\rm{O}}{\rm\small{III}},\mathrm{core}]}$ for σ * could be used only for low luminosity AGNs.

Keywords: active galaxies; emission line galaxies; galaxy kinematics
Discovery of a Surprising Flux Event in White Dwarf HZ 4

HZ 4 is a DA3.4C White Dwarf (WD) and a commonly used photometric standard star. While analyzing its suitability as a calibrator, data from TESS revealed an increase in flux by 43.2%, seen only on Sector 43 observed in 2021 September and October. The event duration is 28.8 hr, and the light curve shape is approximately symmetric and consists of a flux increase preceded and followed by a flux decrease of 11.4%. If periodic, the period would be >77 days. No other objects are observed in the Digital Sky Survey, Galaxy Evolution Explorer, or Wide-Field Infrared Explorer images within the TESS pixel in which HZ 4 resides. The event resembles the flux increases of long-lived WD pulsators, although HZ4 is not in the instability strip. There is no evidence of a binary companion, which suggests HZ4 is not a dwarf nova, nor photometric evidence of any circumstellar material.

Keywords: da stars; white dwarf stars
A Multifrequency ALMA Characterization of Substructures in the GM Aur Protoplanetary Disk

The protoplanetary disk around the T Tauri star GM Aur was one of the first hypothesized to be in the midst of being cleared out by a forming planet. As a result, GM Aur has had an outsized influence on our understanding of disk structure and evolution. We present 1.1 and 2.1 mm ALMA continuum observations of the GM Aur disk at a resolution of ∼50 mas (∼8 au), as well as HCO+ J = 3 - 2 observations at a resolution of ∼100 mas. The dust continuum shows at least three rings atop faint, extended emission. Unresolved emission is detected at the center of the disk cavity at both wavelengths, likely due to a combination of dust and free-free emission. Compared to the 1.1 mm image, the 2.1 mm image shows a more pronounced "shoulder" near R ∼ 40 au, highlighting the utility of longer-wavelength observations for characterizing disk substructures. The spectral index α features strong radial variations, with minima near the emission peaks and maxima near the gaps. While low spectral indices have often been ascribed to grain growth and dust trapping, the optical depth of GM Aur's inner two emission rings renders their dust properties ambiguous. The gaps and outer disk (R > 100 au) are optically thin at both wavelengths. Meanwhile, the HCO+ emission indicates that the gas cavity is more compact than the dust cavity traced by the millimeter continuum, similar to other disks traditionally classified as "transitional."

Keywords: protoplanetary disks; planet formation; circumstellar dust; long baseline interferometry
New Polarimetric Data for the Galilean Satellites: Europa Observations and Modeling

This paper is dedicated to a long-standing problem of the shape of the negative branch of polarization (NBP) for Jupiter's moon Europa, determination of which is crucial for the characterization of the icy regolith on this satellite and similar objects, as well as for further progress in understanding light scattering by particulate surfaces. To establish the shape of Europa's NBP, in 2018-2021 we accomplished high-precision disk-integrated polarimetry of Europa in the UBVR I bands using the identical two-channel photoelectric polarimeters mounted on the 2.6 m Shajn reflector of the Crimean Astrophysical Observatory and the 2 m telescope of the Peak Terskol Observatory. We found that the polarization dependence on the phase angle in each filter is an asymmetric curve with a sharp polarization minimum ${P}_{\min }\approx -0.3 \% $ at phase angle ${\alpha }_{\min }\leqslant 0\buildrel{\circ}\over{.} 4$ , after which the polarization degree gradually increases to positive values, passing the inversion angle at α inv ≈ 6° - 7°. Within the error limits, the parameters P min, ${\alpha }_{\min }$ , and α inv of the NPB are independent of the wavelength in the visible spectrum. The polarization curve clearly demonstrates the so-called polarization opposition effect (POE). Our analysis of the previous and new polarimetric observations of Europa allows us to conclude that the POE is caused by coherent backscattering of sunlight on microscopic icy grains covering Europa's surface. Computer modeling with the numerical radiative transfer coherent backscattering method demonstrates that the best fit to the polarimetric observations and geometric albedo of Europa is provided by a regolith layer of elementary single-scattering albedo ~0.985 and extinction mean free path length 2π l/λ eff ≈ 150, λ eff representing the effective wavelength in the UBVR I spectral bands.

Keywords: jovian satellites; galilean satellites; europa; polarimetry
GRB Afterglows with Energy Injections in AGN Accretion Disks

Active galactic nucleus (AGN) disks are widely considered potential hosts for various high-energy transients, including gamma-ray bursts (GRBs). The reactivation of GRB central engines can provide additional energy to shocks formed during the interaction of the initially ejected GRB jets with the circumburst material, commonly referred to as energy injections. In this paper, we study GRBs occurring in AGN disks within the context of energy injections. We adopt the standard external forward shock (EFS) model and consider both short- and long-duration GRB scenarios. Light curves for two types of radiation, namely, the radiation from the heated disk material (RHDM) and GRB afterglows, are computed. We find that the energy injection facilitates the EFS to break out from the photosphere of the low-density AGN disk at relativistic velocity. Moreover, the energy injection almost does not affect the RHDM but significantly enhances the peak flux of the GRB afterglows.

Keywords: active galactic nuclei; galaxy accretion disks; gamma-ray bursts; relativistic jets; shocks
Binning is Sinning (Supernova Version): The Impact of Self-calibration in Cosmological Analyses with Type Ia Supernovae

Recent cosmological analyses (e.g., JLA, Pantheon) of Type Ia supernovae (SNe Ia) have propagated systematic uncertainties into a covariance matrix and either binned or smoothed the systematic uncertainty vectors in redshift space. We demonstrate that systematic error budgets of these analyses can be improved by a factor of ∼ 1.5 × with the use of unbinned and unsmoothed covariance matrices. To understand this, we employ a separate approach that simultaneously fits for cosmological parameters and additional self-calibrating scale parameters that constrain the size of each systematic. We show that the covariance-matrix approach and scale-parameter approach indeed yield equivalent results, implying that in both cases the data can self-calibrate certain systematic uncertainties, but that this ability is hindered when information is binned or smoothed in redshift space. We review the top systematic uncertainties in current analyses and find that the reduction of systematic uncertainties in the unbinned case depends on whether a systematic is solely degenerate with the cosmological model in redshift space or whether it can be described by additional correlations between supernova properties and luminosity. Furthermore, we show that the power of self-calibration increases with the size of the data set, which presents a tremendous opportunity for upcoming analyses of photometrically classified samples, like those of Legacy Survey of Space and Time (LSST) and the Nancy Grace Roman Telescope (NGRST). However, to take advantage of self-calibration in large, photometrically classified samples, we must first address the issue that binning is required in currently used photometric analysis methods.

Keywords: cosmology; type ia supernovae; astronomical methods; observational cosmology; dark energy; cosmological parameters; astrostatistics
The Cooling of the Central Compact Object in Cas A from 2006 to 2020

We report on the study of six Chandra observations (four epochs) of the Central Compact Object (CCO) in the Cassiopeia A supernova remnant with the ACIS instrument in the subarray mode. This mode minimizes spectrum-distorting instrumental effects such as pileup. The data were taken over a time span of ~14 yr. If a non-magnetic carbon atmosphere is assumed for this youngest known CCO, then the temperature change is constrained to be $\dot{T}=-2900\pm 600$ K yr-1 or $\dot{T}=-4500\pm 800$ K yr-1 (1σ uncertainties) for constant or varying absorbing hydrogen column density. These values correspond to cooling rates of -1.5% ± 0.3% per 10 yr and -2.3% ± 0.4% per 10 yr, respectively. We discuss an apparent increase in the cooling rate in the last five years and the variations of the inferred absorbing hydrogen column densities between epochs. Considered together, these changes could indicate systematic effects such as caused by, e.g., an imperfect calibration of the increasing contamination of the ACIS filter.

Keywords: neutron stars
An Arecibo Search for Fast Radio Transients from M87

The possible origin of millisecond bursts from the giant elliptical galaxy M87 has been scrutinized since the earliest searches for extragalactic fast radio transients undertaken in the late 1970s. Motivated by rapid technological advancements in recent years, we conducted ≃10 hr of L-band (1.15-1.75 GHz) observations of the core of M87 with the Arecibo radio telescope in 2019. Adopting a matched filtering approach, we searched our data for single pulses using trial dispersion measures up to 5500 pc cm-3 and burst durations between 0.3-123 ms. We find no evidence of astrophysical bursts in our data above a 7σ detection threshold. Our observations thus constrain the burst rate from M87 to ≲ 0.1 bursts hr-1 above 1.4 Jy ms, the most stringent upper limit obtained to date. Our nondetection of radio bursts is consistent with expectations of giant pulse emission from a Crab-like young neutron star population in M87. However, the dense, strongly magnetized interstellar medium surrounding the central ~109 M⊙ supermassive black hole of M87 may potentially harbor magnetars that can emit detectable radio bursts during their flaring states.

Keywords: magnetars; neutron stars; radio pulsars; radio transient sources