adsabs/SciX_UAT_keywords huggingface dataset:
H0 Reconstruction with Type Ia Supernovae, Baryon Acoustic Oscillation and Gravitational Lensing Time Delay

There is a persistent H0-tension, now at more than ≳4σ level, between the local distance ladder value and the Planck cosmic microwave background measurement, in the context of flat Lambda-cold-dark-matter (ΛCDM) model. We reconstruct H(z) in a cosmological-model-independent way using three low-redshift distance probes including the latest data from baryon acoustic oscillation, supernova Ia (SN Ia) and gravitational lensing time-delay (GLTD) observations. We adopt general parametric models of H(z) and assume a Gaussian sound horizon at drag epoch, ${r}_{{\rm{s}}}$ , from Planck measurement. The reconstructed Hubble constant H0,rec using Pantheon SN Ia and Baryon Acoustic Oscillations (BAO) data are consistent with the Planck flat ΛCDM value. When including the GLTD data, H0,rec increases mildly, yet remains discrepant with the local measurement at ∼2.2σ level. With our reconstructions being blind to the dark sectors at low redshift, we reaffirm the earlier claims that the Hubble tension is not likely to be solved by modifying the energy budget of the low-redshift universe. We further forecast the constraining ability of future realistic mock BAO data from Dark Energy Spectroscopic Instrument and GLTD data from Large Synoptic Survey Telescope, combining which, we anticipate that the uncertainty of H0,rec would be improved by ∼27%, reaching ${\sigma }_{{H}_{0,\mathrm{rec}}}\approx 0.67$ uncertainty level.

Keywords: observational cosmology; distance indicators; strong gravitational lensing; type ia supernovae
Pursuing the Origin of the Gamma Rays in RX J1713.7-3946 Quantifying the Hadronic and Leptonic Components

We analyzed the TeV gamma-ray image of a supernova remnant RX J1713.7-3946 (RX J1713) through a comparison with the interstellar medium (ISM) and nonthermal X-rays. The gamma-ray data sets at two energy bands of >2 TeV and >250-300 GeV were obtained with H.E.S.S. and utilized in the analysis. We employed a new methodology, which assumes that the gamma-ray counts can be expressed as a linear combination of two terms: one is proportional to the ISM column density and the other proportional to the X-ray count. We then assume that these represent the hadronic and leptonic components, respectively. By fitting the expression to the data pixels, we find that the gamma-ray counts are well represented by a flat plane in the 3D space formed by the gamma-ray counts, the ISM column density, and the X-ray counts. The results using the latest H.E.S.S. data at 4'8 resolution show that the hadronic and leptonic components constitute (67 ± 8)% and (33 ± 8)% of the total gamma rays, respectively, where the two components have been quantified for the first time. The hadronic component is greater than the leptonic component, which reflects the massive ISM of ~104 M⊙ associated with the remnant, lending support for the acceleration of cosmic-ray protons. There is a marginal hint that the gamma rays are suppressed at high gamma-ray counts, which may be ascribed to second-order effects including the shock-cloud interaction and the effect of penetration depth.

Keywords: supernova remnants; interstellar medium; cosmic ray sources; gamma-ray sources; x-ray sources
RR Lyrae-based Distances for 39 Nearby Dwarf Galaxies Calibrated to Gaia eDR3

We provide uniform RR Lyrae-based distances to 39 dwarf galaxies in and around the Local Group. We determine distances based on a Bayesian hierarchical model that uses periods and magnitudes of published RR Lyrae in dwarf galaxies and is anchored to well-studied Milky Way (MW) RR Lyrae with spectroscopic metallicities and Gaia eDR3 parallaxes. Gaia eDR3 parallaxes for the anchor sample are a factor of 2, on average, more precise than DR2 parallaxes, and allow for a much better constrained period-luminosity-metallicity relation. While ~75% of our distances are within 1σ of recent RR Lyrae distances in the literature, our distances are also ~2-3 times more precise than distances in the literature, on average. On average, our distances are ~0.05 mag closer than distances in the literature, as well as ~0.06 mag closer than distances derived using a theoretical period-luminosity-metallicity relation. These discrepancies are largely due to our eDR3 parallax anchor. We show that the Hipparcos-anchored RR Lyrae distance scale of Carretta et al. overpredicts distances to MW RR Lyrae by ~0.05 mag. The largest uncertainties in our distances are (i) the lack of direct metallicity measurements for RR Lyrae and (ii) the heterogeneity of published RR Lyrae photometry. We provide simple formulae to place new dwarf galaxies with RR Lyrae on a common distance scale with this work. We provide a public code that can easily incorporate additional galaxies and data from future surveys, providing a versatile framework for the cartography of the local universe with RR Lyrae.

Keywords: local group; rr lyrae variable stars; galaxy distances; dwarf galaxies
A Detectable Ultra-high-energy Cosmic-Ray Outburst from GRB 221009A

Gamma-ray bursts (GRBs) have been proposed as one of the promising sources of ultra-high-energy cosmic rays (UHECRs), but observational evidence is still lacking. The nearby brightest of all time GRB 221009A, a once in 1000 yr event, is able to accelerate protons to ∼103 EeV, and then generate extremly energetic neutrons via the photomeson production interaction. Protons arriving at the Milky Way are dominated by neutron-decay-induced protons. The intergalactic magnetic fields would not yield a sizable delay of the ≥10 EeV cosmic rays if its strength is ≲10‑13 G, while Galactic magnetic fields would cause a significant time delay. We predict that a UHECR burst from GRB 221009A would be detectable by the Pierre Auger Observatory and the TA×4, within ∼10 yr. The detection of such a UHECR outburst will provide the direct evidence for UHECR acceleration in GRBs.

Keywords: gamma-ray bursts; cosmic rays; extragalactic magnetic fields; cosmic ray sources; high energy astrophysics
Radio Spectra of Luminous, Heavily Obscured WISE-NVSS Selected Quasars

We present radio spectra spanning 0.1-10 GHz for the sample of heavily obscured luminous quasars with extremely red mid-infrared-optical colors and compact radio emission. The spectra are constructed from targeted 10 GHz observations and archival radio survey data that together yield 6-11 flux-density measurements for each object. Our primary result is that most (62%) of the sample have peaked or curved radio spectra and many (37%) could be classified as Gigahertz-Peaked Spectrum (GPS) sources. This indicates compact emission regions likely arising from recently triggered radio jets. Assuming synchrotron self-absorption (SSA) generates the peaks, we infer compact source sizes (3-100 pc) with strong magnetic fields (6-100 mG) and young ages (30-104 yr). Conversely, free-free absorption (FFA) could also create peaks due to the high column densities associated with the deeply embedded nature of the sample. However, we find no correlations between the existence or frequency of the peaks and any parameters of the MIR emission. The high-frequency spectral indices are steep (α ≈ -1) and correlate, weakly, with the ratio of MIR photon energy density to magnetic energy density, suggesting that the spectral steepening could arise from inverse Compton scattering off the intense MIR photon field. This study provides a foundation for combining multifrequency and mixed-resolution radio survey data for understanding the impact of young radio jets on the ISM and star-formation rates of their host galaxies. faGithub

Keywords: radio loud quasars; supermassive black holes; galaxy evolution; spectral energy distribution; radio active galactic nuclei; radio jets; radio continuum emission
The Radial Distribution of Ion-scale Waves in the Inner Heliosphere

Determining the mechanism responsible for plasma heating and particle acceleration is a fundamental problem in the study of the heliosphere. Due to efficient wave-particle interactions of ion-scale waves with charged particles, these waves are widely believed to be a major contributor to ion energization, and their contribution considerably depends on the wave occurrence rate. By analyzing the radial distribution of quasi-monochromatic ion-scale waves observed by the Parker Solar Probe, this work shows that the wave occurrence rate is significantly enhanced in the near-Sun solar wind, specifically 21%-29% below 0.3 au, in comparison to 6%-14% beyond 0.3 au. The radial decrease of the wave occurrence rate is not only induced by the sampling effect of a single spacecraft detection, but also by the physics relating to the wave excitation, such as the enhanced ion beam instability in the near-Sun solar wind. This work also shows that the wave normal angle θ, the absolute value of ellipticity ϵ, the wave frequency f normalized by the proton cyclotron frequency f cp, and the wave amplitude δ B normalized by the local background magnetic field B 0 slightly vary with the radial distance. The median values of θ, ∣ϵ∣, f, and δ B are about 9°, 0.73, 3f cp, and 0.01B 0, respectively. Furthermore, this study proposes that the wave mode natures of the observed left-handed and right-handed polarized waves correspond to the Alfvén ion cyclotron mode wave and the fast magnetosonic whistler mode wave, respectively.

Keywords: plasma physics; space plasmas; solar wind
Super-Rayleigh Slopes in Transmission Spectra of Exoplanets Generated by Photochemical Haze

Spectral slopes in optical transmission spectra of exoplanetary atmospheres encapsulate information on the properties of exotic clouds. The slope is usually attributed to the Rayleigh scattering caused by tiny aerosol particles, whereas recent retrieval studies have suggested that the slopes are often steeper than the canonical Rayleigh slopes. Here, we propose that photochemical haze formed in vigorously mixing atmospheres can explain such super-Rayleigh slopes. We first analytically show that the spectral slope can be steepened by the vertical opacity gradient in which atmospheric opacity increases with altitude. Using a microphysical model, we demonstrate that such an opacity gradient can be naturally generated by photochemical haze, especially when the eddy mixing is substantially efficient. The transmission spectra of hazy atmospheres can be demarcated into four typical regimes in terms of the haze mass flux and eddy diffusion coefficient. We find that the transmission spectrum can have a spectral slope 2-4 times steeper than the Rayleigh slope if the eddy diffusion coefficient is sufficiently high and the haze mass flux falls into a moderate value. Based on the eddy diffusion coefficient suggested by a recent study of atmospheric circulations, we suggest that photochemical haze preferentially generates super-Rayleigh slopes at planets with equilibrium temperatures of 1000-1500 K, which might be consistent with results of recent retrieval studies. Our results would help interpret the observations of spectral slopes from the perspective of haze formation.

Keywords: exoplanet atmospheres; hot jupiters; optical observation; transmission spectroscopy
A Look at Outbursts of Comet C/2014 UN271 (Bernardinelli-Bernstein) near 20 au

Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the discovery of the Oort cloud comet C/2014 UN271 (Bernardinelli-Bernstein) and its observed activity out to ~26 au. Through observations of this comet's optical brightness and behavior, we can potentially discern the drivers of activity in the outer solar system. We present a study of the activity of comet Bernardinelli-Bernstein with broad-band optical photometry taken at 19-20 au from the Sun (2021 June to 2022 February) as part of the LCO Outbursting Objects Key (LOOK) Project. Our analysis shows that the comet's optical brightness during this period was initially dominated by cometary outbursts, stochastic events that ejected ~107 to ~108 kg of material on short (<1 day) timescales. We present evidence for three such outbursts occurring in 2021 June and September. The nominal nuclear volumes excavated by these events are similar to the 10-100 m pit-shaped voids on the surfaces of short-period comet nuclei, as imaged by spacecraft. Two out of three Oort cloud comets observed at large pre-perihelion distances exhibit outburst behavior near 20 au, suggesting such events may be common in this population. In addition, quiescent CO-driven activity may account for the brightness of the comet in 2022 January to February, but that variations in the cometary active area (i.e., the amount of sublimating ice) with heliocentric distance are also possible.

Keywords: optical astronomy; broad band photometry; long period comets; coma dust; comet surfaces
nuance: Efficient Detection of Planets Transiting Active Stars

The detection of planetary transits in the light curves of active stars, featuring correlated noise in the form of stellar variability, remains a challenge. Depending on the noise characteristics, we show that the traditional technique that consists of detrending a light curve before searching for transits alters their signal-to-noise ratio and hinders our capability to discover exoplanets transiting rapidly rotating active stars. We present nuance, an algorithm to search for transits in light curves while simultaneously accounting for the presence of correlated noise, such as stellar variability and instrumental signals. We assess the performance of nuance on simulated light curves as well as on the Transiting Exoplanet Survey Satellite light curves of 438 rapidly rotating M dwarfs. For each data set, we compare our method to five commonly used detrending techniques followed by a search with the Box-Least-Squares algorithm. Overall, we demonstrate that nuance is the most performant method in 93% of cases, leading to both the highest number of true positives and the lowest number of false-positive detections. Although simultaneously searching for transits while modeling correlated noise is expected to be computationally expensive, we make our algorithm tractable and available as the JAX-powered Python package nuance, allowing its use on distributed environments and GPU devices. Finally, we explore the prospects offered by the nuance formalism and its use to advance our knowledge of planetary systems around active stars, both using space-based surveys and sparse ground-based observations.

Keywords: exoplanet detection methods; stellar activity; time series analysis; gaussian processes regression; computational methods; gpu computing
Deflection of Global Ion Flow by the Martian Crustal Magnetic Fields

Without the protection of a global magnetic field, erosion of the Martian ionosphere by the solar wind leads to abundant loss of atmospheric particles. Although the crustal magnetic fields in the Martian southern hemisphere are strong enough to affect the dayside-induced magnetosphere, there is still limited evidence for the deflection of the solar winds by the crustal magnetic fields. With 4 years of ion data measured by the Mars Atmosphere and Volatile EvolutioN mission, we investigate the flow pattern of protons, O+, and ${{{\rm{O}}}_{2}}^{+}$ when the crustal fields rotate to different local times. Our result is the first evidence that suggests the crustal magnetic fields can withstand the solar wind flows on the Martian dayside and can effectively trap heavy ions below 1000 km. The gyroradii of heavy ions in the strong crustal fields regions are one order of magnitude smaller than in other regions. The trapping effect causes different flow patterns, while the crustal fields rotate to different subsolar regions but are attenuated at higher altitudes. Observations provide essential information to investigate the effect of the crustal magnetic fields on heavy-ion flows and understand the role of the crustal magnetic fields in the interaction between the solar wind and the Martian atmosphere.

Keywords: mars; magnetic anomalies; solar-planetary interactions; planetary magnetospheres
A Random Forest Approach to Identifying Young Stellar Object Candidates in the Lupus Star-forming Region

The identification and characterization of stellar members within a star-forming region are critical to many aspects of star formation, including formalization of the initial mass function, circumstellar disk evolution, and star formation history. Previous surveys of the Lupus star-forming region have identified members through infrared excess and accretion signatures. We use machine learning to identify new candidate members of Lupus based on surveys from two space-based observatories: ESA's Gaia and NASA's Spitzer. Astrometric measurements from Gaia's Data Release 2 and astrometric and photometric data from the Infrared Array Camera on the Spitzer Space Telescope, as well as from other surveys, are compiled into a catalog for the random forest (RF) classifier. The RF classifiers are tested to find the best features, membership list, non-membership identification scheme, imputation method, training set class weighting, and method of dealing with class imbalance within the data. We list 27 candidate members of the Lupus star-forming region for spectroscopic follow-up. Most of the candidates lie in Clouds V and VI, where only one confirmed member of Lupus was previously known. These clouds likely represent a slightly older population of star formation.

Keywords: t associations; moving clusters; young star clusters; random forests
SOFIA/FORCAST Galactic Center Legacy Survey: Overview

The Galactic Center contains some of the most extreme conditions for star formation in our Galaxy, as well as many other phenomena that are unique to this region. Given our relative proximity to the Galactic Center, we are able to study details of physical processes to a level that is simply not yet possible for more distant galaxies, yielding an otherwise inaccessible view of the nuclear region of a galaxy. We recently carried out a targeted imaging survey of mid-infrared bright portions of the Galactic Center at 25 and 37 μm using the FORCAST instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA). This survey was one of the inaugural Legacy Programs from SOFIA cycle 7, observing a total area of 403 arcmin2 (2180 pc2), including the Sgr A, B, and C complexes. Here we present an overview of the survey strategy, observations, and data reduction as an accompaniment to the initial public release of the survey data. We discuss interesting regions and features within the data, including extended features near the circumnuclear disk, structures in the Arched Filaments and Sickle H II regions, and signs of embedded star formation in Sgr B2 and Sgr C. We also feature a handful of less well studied mid-infrared sources located between Sgr A and Sgr C that could be sites of relatively isolated star formation activity. Last, we discuss plans for subsequent publications and future data releases from the survey.

Keywords: h ii regions; galactic center; star formation; star forming regions
Dependence of the IBEX Ribbon Geometry on Pitch-Angle Scattering outside the Heliopause

Interstellar Boundary Explorer (IBEX) observations of the "ribbon" of enhanced energetic neutral atom (ENA) fluxes show that it is a persistent feature that approximately forms a circle in the sky, likely formed from secondary ENAs whose source lies outside the heliopause. The IBEX ribbon's geometry (radius and center) depends on ENA energy and is believed to be influenced by the draping of the ISMF and the latitudinal structure of the SW. In this study, we demonstrate that the ribbon's geometry also depends on the pitch-angle scattering rate of ions outside the heliopause, which we simulate under strong and weak-scattering limits. The ribbon radius in the weak-scattering model is ∼4° larger than IBEX observations at most energies, and the strong-scattering model produces radii statistically consistent with IBEX at 1.1-2.7 keV. The simulated ribbon center is shifted between ∼2° and 5° along the B-V plane away from the IBEX center for the weak and strong limits, respectively, suggesting that the pristine ISMF far from the heliosphere is shifted ∼2°-5° away from our simulated ISMF toward the VLISM inflow direction. However, the magnitude needs to be decreased from ∼3 to 2 μG for the weak-scattering model to be consistent with the IBEX ribbon radius, which seems unlikely. We also find that the presence of interstellar He does not significantly affect the ribbon in the strong-scattering limit but yields weaker agreement with data in the weak limit. Our results slightly favor the strong-scattering limit for the ribbon's origin.

Keywords: heliosphere; pickup ions; interstellar medium; heliosheath; interstellar magnetic fields
The Refined Transit Ephemeris of TOI-2180 b

The Transiting Exoplanet Survey Satellite (TESS) observed a single transit of the giant exoplanet TOI-2180 b in Sector 19 of its primary mission. A subsequent effort to characterize this system found that the orbital period of TOI-2180 b is 260.8 ± 0.6 days. This level of precision precludes most efforts to detect future transits and to further understand this exoplanet. We present a new transit of TOI-2180 b observed by TESS in Sector 48 and update the planet's transit ephemeris with its precisely measured orbital period. The refined ephemeris enables future transit observations to explore this planet's atmosphere or to search for rings or moons.

Keywords: exoplanet astronomy; transits; extrasolar gaseous giant planets
Red Giant Rotational Inversion Kernels Need Nonlinear Surface Corrections

Asteroseismology is our only means of measuring the rotations of stars in their interiors, rather than at their surfaces. Some techniques for measurements of this kind-"rotational inversions"-require the shapes of linear response kernels computed from reference stellar models to be representative of those in the stars they are intended to match. This is not the case in evolved stars exhibiting gravitoacoustic mixed modes: we show that the action of the asteroseismic surface term-systematic errors in the modeling of near-surface layers-changes the shapes of their inversion kernels. Corrections for the surface term are not ordinarily considered necessary for rotational inversions. We show how this may have caused previous estimates of red-giant envelope rotation rates from mixed-mode asteroseismic inversions to have been unintentionally contaminated by core rotation as a result, with errors comparable to the entire reported estimates. We derive a mitigation procedure for this hitherto unaccounted systematic error, and demonstrate its viability and effectiveness. We recommend this mitigation be applied when revising existing rotational inversions. Finally, we discuss both the prospects for applying such mitigation to the harder problem of inversions for stellar structure (rather than rotation), as well as the broader implications of this systematic error with regard to the longstanding problem of internal angular momentum transport.

Keywords: asteroseismology; perturbation methods; stellar oscillations; stellar rotation; red giant stars
A Photohadronic Interpretation of H.E.S.S. Afterglow Observations of GRB 221009A

The High Energy Stereoscopic System (H.E.S.S.) started observing the extremely powerful long-duration gamma-ray burst (GRB) GRB 221009A starting 53 hr after the triggering event. The H.E.S.S. collaboration carried out observations on 2022 October 11, 12, and 17 under poor atmospheric conditions, without detecting significant very-high-energy photons from the source and computed the upper limits of the fluxes for the different nights. We study these flux upper limits by using the photohadronic model and show that the interaction of high-energy protons with synchrotron seed photons in the forward-shock region of the GRB jet exhibits behavior compatible with the upper limits computed by the H.E.S.S. collaboration.

Keywords: particle astrophysics; blazars; gamma-ray bursts; relativistic jets