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Testing the Cosmic Opacity at Higher Redshifts: Implication from Quasars with Available UV and X-Ray Observations

In this paper, we present a cosmological model-independent test for the cosmic opacity at high redshifts (z ∼ 5). We achieve this with the opacity-dependent luminosity distances derived from the nonlinear relation between X-ray and UV emissions of quasars, combined with two types of opacity-independent luminosity distances derived from the Hubble parameter measurements and simulated gravitational wave (GW) events achievable with the Einstein Telescope (ET). In the framework of two phenomenological parameterizations adopted to describe cosmic opacity at high redshifts, our main results show that a transparent universe is supported by the current observational data at a 2σ confidence level. However, the derived value of the cosmic opacity is slightly sensitive to the parameterization of τ(z), which highlights the importance of choosing a reliable parameterization to describe the optical depth τ(z) in the early universe. Compared with previous works, the combination of the quasar data and the H(z)/GW observations in similar redshift ranges provides a novel way to confirm a transparent universe (ɛ = 0 at higher redshifts z ∼ 5), with an accuracy of Δɛ ∼ 10-2. More importantly, our findings indicate that a strong degeneracy between the cosmic-opacity parameter and the parameters characterizing the LUV - LX relation of quasars, which reinforces the necessity of proper calibration for this new type of high-redshift standard candle (in a cosmological model-independent way).

Keywords: quasars; cosmological parameters
Microphysics of Relativistic Collisionless Electron-ion-positron Shocks

We perform particle-in-cell simulations to elucidate the microphysics of relativistic weakly magnetized shocks loaded with electron-positron pairs. Various external magnetizations σ ≲ 10-4 and pair-loading factors Z ± ≲ 10 are studied, where Z ± is the number of loaded electrons and positrons per ion. We find the following: (1) The shock becomes mediated by the ion Larmor gyration in the mean field when σ exceeds a critical value σ L that decreases with Z ±. At σ ≲ σ L the shock is mediated by particle scattering in the self-generated microturbulent fields, the strength and scale of which decrease with Z ±, leading to lower σ L. (2) The energy fraction carried by the post-shock pairs is robustly in the range between 20% and 50% of the upstream ion energy. The mean energy per post-shock electron scales as ${\overline{E}}_{{\rm{e}}}\propto {\left({Z}_{\pm }+1\right)}^{-1}$ . (3) Pair loading suppresses nonthermal ion acceleration at magnetizations as low as σ ≈ 5 × 10-6. The ions then become essentially thermal with mean energy ${\overline{E}}_{{\rm{i}}}$ , while electrons form a nonthermal tail, extending from $E\sim {\left({Z}_{\pm }+1\right)}^{-1}{\overline{E}}_{{\rm{i}}}$ to ${\overline{E}}_{{\rm{i}}}$ . When σ = 0, particle acceleration is enhanced by the formation of intense magnetic cavities that populate the precursor during the late stages of shock evolution. Here, the maximum energy of the nonthermal ions and electrons keeps growing over the duration of the simulation. Alongside the simulations, we develop theoretical estimates consistent with the numerical results. Our findings have important implications for models of early gamma-ray burst afterglows.

Keywords: high energy astrophysics; shocks; non-thermal radiation sources; plasma astrophysics; gamma-ray bursts
Peas in a Pod? Radius Correlations in Kepler Multiplanet Systems

We address the claim of Weiss et al. that the radii of adjacent planets in Kepler multiplanet systems are correlated. We explore two simple toy models—in the first the radii of the planets are chosen at random from a single universal distribution, and in the second we postulate several types of systems with distinct radius distributions. We show that an apparent correlation between the radii of adjacent planets similar to the one reported by Weiss can arise in both models. In addition the second model fits the radius and signal-to-noise distribution of the observed planets. We also comment on the validity of a commonly used correction that is used to estimate intrinsic planet occurrence rates, based on weighting planets by the inverse of their detectability.

Keywords: exoplanets; exoplanet systems
The Advantages of Global Photometric Models in Fitting Transit Variations

Estimation of planetary orbital and physical parameters from light-curve data relies heavily on the accurate interpretation of Transit Timing Variation (TTV) measurements. In this letter, we review the process of TTV measurement and compare two fitting paradigms-one that relies on making transit-by-transit timing estimates and then fitting a TTV model to the observed timings, and one that relies on fitting a global flux model to the entire light-curve data set simultaneously. The latter method is achieved either by solving for the underlying planetary motion (often referred to as "photodynamics"), or by using an approximate or empirical shape of the TTV signal. We show that, across a large range of the transit S/N regime, the probability distribution function of the mid-transit time significantly deviates from a Gaussian, even if the flux errors do distribute normally. Treating the timing uncertainties as if they are distributed normally leads, in such a case, to a wrong interpretation of the TTV measurements. We illustrate these points using numerical experiments and conclude that a fitting process that relies on a global flux fitting, rather than the derived TTVs, should be preferred.

Keywords: light curves; exoplanets; transit timing variation method
Migrating Planets into Ultra-short-period Orbits during Episodic Accretion Events

Ultra-short-period (USP) planets reside inside the expected truncation radius for typical T Tauri disks. As a result, their current orbital locations require an explanation beyond standard disk migration or in situ formation. Modern theories of planet-disk interactions indicate that once a planet migrates close to the disk's inner truncation radius, Type I torques vanish or switch direction, depending on the stellar and disk conditions, so that the planet is expected to stop its orbital decay and become trapped. In this work, we show that that magnetically driven sub-Keplerian gas flow in the inner disk can naturally counteract these effects and produce systems with USP planets at their observed orbital radii. The sub-Keplerian gas flow provides a headwind to small planets, and the resulting torque can overcome the effects of outward Type I migration near the corotation radius. For suitable disk and planet parameters, the torques due to the sub-Keplerian gas flow lead to inward migration on a rapid timescale. Over the time span of an FU Ori outburst, which moves the disk truncation radius inward, the rapid headwind migration can place planets in USP orbits. The combination of headwind migration and FU Ori outbursts thus provides a plausible mechanism to move small planets from a = 0.05-0.1 au down to a = 0.01-0.02 au. This effect is amplified for low-mass planets, consistent with existing observations.

Keywords: exoplanet migration; fu orionis stars; protoplanetary disks
Volatile Mass Partitioned among the Atmosphere, Mantle, and Core in Proto-Mars

We analyze the distribution of volatiles such as water, hydrogen, and carbon within the atmosphere, mantle, and core of Mars during its accretion stages. The partitioning of these volatiles is crucial as it influences the generation of intrinsic magnetic fields, mantle convection, and magmatic activity. The study suggests that the accretion process is responsible for the presence of water and light elements within the Martian mantle and core. We employ a hybrid-type proto-atmosphere model, which considers an upper layer composed of nebula components and a lower layer made up of degassed components from the impact degassing of the simplified building blocks based on the two-component model. Our numerical analysis implies that the formation of a magma ocean at this high temperature and pressure after around the half-size of the present Mars triggers the migration of water vapor, carbon, and hydrogen from the primordial atmosphere into the planetary interior. Ultimately, several 1021 kg of water could have been distributed to the mantle and, if degassed again by the formation of flood basalts on the Tharsis Plateau, could have supplied Mars' ancient oceans. Meanwhile, several 1020 kg of carbon and 1019 kg of hydrogen (equivalent to 1020 kg H2O) were found to be distributed in the core. Although the distribution of sulfur was simplified so that all of the sulfur is in the core, a result of sulfur accounting for 14 wt% to 19 wt.% of the core mass would be consistent with the core density suggested by InSight.

Keywords: mars; solar system terrestrial planets; atmospheric evolution; planetary cores; mantle; planetary structure
Amplitude of the Usual Cosmic Ray Diurnal and Enhanced Anisotropies: Implications for the Observed Magnitude, Timing, and Ranking of Forbush Decreases

Cosmic ray (CR) diurnal anisotropy and Forbush decreases (FDs), as well as the relationship between them, have received considerable study. Several astrophysicists have focused on the speculated impact of FDs on the amplitude of the diurnal CR variations on different timescales. In an attempt to disentangle the contribution of FDs, days of Forbush events are traditionally excluded while calculating the diurnal amplitude in individual neutron monitor (NM) data. But the implications of CR diurnal anisotropy on the magnitude of FDs are rarely investigated in detail. Recently, an effort was made, using a combination of Fast Fourier transform and FD-location algorithms, to account for the contribution of CR diurnal anisotropy on the number, magnitude, and timing of FDs. With some technical advancements, the efficiency of the software is tested in the current work using CR data measured by the oldest CR observatory (Climax) from 1953 to 2006. We find strong and statistically significant correlations between FD magnitude calculated from raw and Fourier transformed CR data and the amplitude of diurnal anisotropy. The relationship is stronger in the case of the Fourier transformed signal, lending credence to the idea that CR anisotropy is a part of Forbush events. In order to validate the observed relationship between the amplitude of CR diurnal variations, magnitude, and timing of FDs, large volumes of data from the Moscow, McMurdo, and Potchefstroom NMs were also analyzed. The significant CR intensity decreases (FD magnitude >5%) at the four stations were ranked according to their magnitudes.

Keywords: galactic cosmic rays; cosmic ray sources
Effect of Rotation on Wave Mixing in Intermediate-mass Stars

Internal gravity waves are likely to cause mixing in stellar interiors. Studies show that the mixing by these waves changes drastically across age and mass. Here, we study the effect of rotation on this wave mixing by considering a 7 M ⊙ model at zero-age main sequence and mid-main sequence. We compare the mixing profiles at a range of rotation rates (1 × 10‑5, 2 × 10‑5, 3 × 10‑5, 4 × 10‑5, and 1 × 10‑4 rad s‑1) and observe that the mixing decreases with decreasing Rossby number. This can be attributed to the effect of rotation on convection, which influences the amplitude with which the waves are excited near the convective–radiative interface.

Keywords: stellar evolution; hydrodynamics
Constraints on Cosmological Parameters from the 500 deg2 SPTPOL Lensing Power Spectrum

We present cosmological constraints based on the cosmic microwave background (CMB) lensing potential power spectrum measurement from the recent 500 deg2 SPTpol survey, the most precise CMB lensing measurement from the ground to date. We fit a flat ΛCDM model to the reconstructed lensing power spectrum alone and in addition with other data sets: baryon acoustic oscillations (BAO), as well as primary CMB spectra from Planck and SPTpol. The cosmological constraints based on SPTpol and Planck lensing band powers are in good agreement when analyzed alone and in combination with Planck full-sky primary CMB data. With weak priors on the baryon density and other parameters, the SPTpol CMB lensing data alone provide a 4% constraint on ${\sigma }_{8}{{\rm{\Omega }}}_{m}^{0.25}=0.593\pm 0.025$ . Jointly fitting with BAO data, we find ${\sigma }_{8}=0.779\pm 0.023$ , ${{\rm{\Omega }}}_{m}={0.368}_{-0.037}^{+0.032}$ , and ${H}_{0}={72.0}_{-2.5}^{+2.1}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ , up to $2\sigma $ away from the central values preferred by Planck lensing + BAO. However, we recover good agreement between SPTpol and Planck when restricting the analysis to similar scales. We also consider single-parameter extensions to the flat ΛCDM model. The SPTpol lensing spectrum constrains the spatial curvature to be ${{\rm{\Omega }}}_{K}=-0.0007\pm 0.0025$ and the sum of the neutrino masses to be $\sum {m}_{\nu }\lt 0.23$ eV at 95% C.L. (with Planck primary CMB and BAO data), in good agreement with the Planck lensing results. With the differences in the signal-to-noise ratio of the lensing modes and the angular scales covered in the lensing spectra, this analysis represents an important independent check on the full-sky Planck lensing measurement.

Keywords: cosmological parameters; weak gravitational lensing; cosmic microwave background radiation
Observational Evidence of S-web Source of the Slow Solar Wind

From 2022 March 18 to 21, NOAA Active Region (AR) 12967 was tracked simultaneously by Solar Orbiter at 0.35 au and Hinode/EIS at Earth. During this period, strong blueshifted plasma upflows were observed along a thin, dark corridor of open magnetic field originating at the AR's leading polarity and continuing toward the southern extension of the northern polar coronal hole. A potential field source surface model shows large lateral expansion of the open magnetic field along the corridor. Squashing factor Q-maps of the large-scale topology further confirm super-radial expansion in support of the S-web theory for the slow wind. The thin corridor of upflows is identified as the source region of a slow solar wind stream characterized by ~300 km s-1 velocities, low proton temperatures of ~5 eV, extremely high density >100 cm-3, and a short interval of moderate Alfvénicity accompanied by switchback events. When the connectivity changes from the corridor to the eastern side of the AR, the in situ plasma parameters of the slow solar wind indicate a distinctly different source region. These observations provide strong evidence that the narrow open-field corridors, forming part of the S-web, produce some extreme properties in their associated solar wind streams.

Keywords: slow solar wind
GHOST: Using Only Host Galaxy Information to Accurately Associate and Distinguish Supernovae

We present GHOST, a database of 16,175 spectroscopically classified supernovae (SNe) and the properties of their host galaxies. We have constructed GHOST using a novel host galaxy association method that employs deep postage stamps of the field surrounding a transient. Our gradient ascent method achieves fewer misassociations for low-z hosts and higher completeness for high-z hosts than previous methods. Using dimensionality reduction, we identify the host galaxy properties that distinguish SN classes. Our results suggest that the host galaxies of superluminous SNe, Type Ia SNe, and core-collapse SNe can be separated by brightness and derived extendedness measures. Next, we train a random forest model to predict SN class using only host galaxy information and the radial offset of the SN. We can distinguish Type Ia SNe and core-collapse SNe with ∼70% accuracy without any photometric or spectroscopic data from the event itself. Vera C. Rubin Observatory will usher in a new era of transient population studies, demanding improved photometric tools for rapid identification and classification of transient events. By identifying the host features with high discriminatory power, we will maintain SN sample purities and continue to identify scientifically relevant events as data volumes increase. The GHOST database and our corresponding software for associating transients with host galaxies are both publicly available through the astro_ghost package.

Keywords: supernovae; classification; random forests; support vector machine; astronomy databases; open source software
Measurement of Void Bias Using Separate Universe Simulations

Cosmic voids are biased tracers of the large-scale structure of the universe. Separate universe simulations (SUS) enable accurate measurements of this biasing relation by implementing the peak-background split (PBS). In this work, we apply the SUS technique to measure the void bias parameters. We confirm that the PBS argument works well for underdense tracers. The response of the void size distribution depends on the void radius. For voids larger (smaller) than the size at the peak of the distribution, the void abundance responds negatively (positively) to a long wavelength mode. The linear bias from the SUS is in good agreement with the cross power spectrum measurement on large scales. Using the SUS, we have detected the quadratic void bias for the first time in simulations. We find that b2 is negative when the magnitude of b1 is small, and that it becomes positive and increases rapidly when $| {b}_{1}| $ increases. We compare the results from voids identified in the halo density field with those from the dark matter distribution, and find that the results are qualitatively similar, but the biases generally shift to the larger voids sizes.

Keywords: cosmology; voids; large-scale structure of the universe; cosmic web; dark matter distribution
Size–Stellar Mass Relation and Morphology of Quiescent Galaxies at z ≥ 3 in Public JWST Fields

We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at z ≥ 3 using the Near-Infrared Camera (NIRCam) on board the James Webb Space Telescope (JWST). Based on a sample selected by UVJ color or NUVUVJ color, we focus on 26 quiescent galaxies with $9.8\lt \mathrm{log}({M}_{\star }/{M}_{\odot })\lt 11.4$ at 2.8 < z phot < 4.6 with publicly available JWST data. Their sizes are constrained by fitting the Sérsic profile to all available NIRCam images. We see a negative correlation between the observed wavelength and the size and derive their size at the rest frame 0.5 μm using size measurements in multiple bands. Our quiescent galaxies show a significant correlation between the rest-frame 0.5 μm size and the stellar mass at z ≥ 3. The analytical fit for them at $\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 10.3$ implies that our size–stellar mass relations are below those at lower redshifts, with the amplitude of ∼0.6 kpc at M ⋆ = 5 × 1010 M ⊙. This value agrees with the extrapolation of the size evolution of quiescent galaxies at z < 3 in the literature, implying that the size of quiescent galaxies increases monotonically from z ∼ 3–5. Our sample mainly comprises galaxies with bulge-like structures according to their median Sérsic index and axis ratio of n ∼ 3–4 and q ∼ 0.6–0.8, respectively. On the other hand, there is a trend of increasing fraction of galaxies with low Sérsic index at higher redshift, suggesting 3 < z < 5 might be the epoch of onset of morphological transformation with a fraction of very notable disky quenched galaxies.

Keywords: galaxy evolution; galaxy quenching; high-redshift galaxies; galaxy radii; quenched galaxies
Observations of a Radial Density Gradient in the Very Local Interstellar Medium by Voyager 2

Beginning on 2020 June 19, at a heliocentric distance of 124.2 au, the Voyager 2 Plasma Wave Science instrument began to observe radio emissions followed by electron plasma oscillations in its 3.11 kHz spectrum analyzer channel. Plasma oscillations at this frequency imply an electron density in the range of 0.12 cm-3 ± 15%, although some response in the 1.78 kHz channel near the peak of the plasma oscillations suggest a density of 0.087 cm-3 ± 8%. Shortly after Voyager 2 crossed the heliopause, in late 2019 January, the Voyager 2 Plasma Wave Science instrument detected plasma oscillations in its 1.78 kHz channel giving an electron density of 0.039 cm-3 ± 15%. While the Voyager spectrum analyzer affords relatively poor spectral resolution, the recent observation of plasma oscillations in the 3.11 kHz channel provides definitive evidence of a radial density gradient in the very local interstellar medium (VLISM), just beyond the heliopause with a magnitude similar to that observed by Voyager 1 obtained with higher spectral resolution measurements. Plasma oscillations observed by Voyager 1 range from frequencies as low as 2.1 kHz increasing to about 3.2 kHz, giving an electron density profile that increases from about 0.055 to about 0.13 cm-3 over a distance spanning some 20 au. Given the 67° difference in heliographic latitude and 43° difference in longitude between the two Voyagers, the new Voyager 2 observations imply that the density gradient is a large-scale feature of the VLISM in the general direction of the heliospheric nose.

Keywords: interstellar medium; interstellar plasma
CECILIA: The Faint Emission Line Spectrum of z 2-3 Star-forming Galaxies

We present the first results from Chemical Evolution Constrained Using Ionized Lines in Interstellar Aurorae (CECILIA), a Cycle 1 JWST NIRSpec/MSA program that uses ultra-deep ~30 hr G235M/F170LP observations to target multiple electron temperature-sensitive auroral lines in the spectra of 33 galaxies at z ~ 1-3. Using a subset of 23 galaxies, we construct two ~600 object-hour composite spectra, both with and without the stellar continuum, and use these to investigate the characteristic rest-optical (λ rest ≈ 5700-8500 Å) spectrum of star-forming galaxies at the peak epoch of cosmic star formation. Emission lines of eight different elements (H, He, N, O, Si, S, Ar, and Ni) are detected, with most of these features observed to be ≲3% the strength of Hα. We report the characteristic strength of three auroral features ([N II]λ5756, [S III]λ6313, and [O II]λ λ7322, 7332), as well as other semi-strong and faint emission lines, including forbidden [Ni II]λ λ7380, 7414 and permitted O I λ8449, some of which have never before been observed outside of the local Universe. Using these measurements, we find T e [N II] = 13,630 ± 2540 K, representing the first measurement of electron temperature using [N II] in the high-redshift Universe. We also see evidence for broad line emission with a FWHM of ${536}_{-167}^{+45}$ km s-1; the broad component of Hα is 6.01%-28.31% the strength of the narrow component and likely arises from star-formation-driven outflows. Finally, we briefly comment on the feasibility of obtaining large samples of faint emission lines using JWST in the future.

Keywords: high-redshift galaxies; emission line galaxies; galaxy spectroscopy; chemical abundances