adsabs/SciX_UAT_keywords huggingface dataset:
Eclipsing Binaries Found by the EREBOS Project: Gaia DR2 6097540197980557440-a Deeply Eclipsing sdB+dM System

We present time-series spectroscopy and photometry of Gaia DR2 6097540197980557440, a new deeply eclipsing hot subdwarf B (sdB) + M dwarf (dM) binary. We discovered this object during the course of the Eclipsing Reflection Effect Binaries from Optical Surveys (EREBOS) project, which aims to find new eclipsing sdB+dM binaries (HW Vir systems) and increase the small sample of studied systems. In addition to the primary eclipse, which is in excess of ~5 mag in the optical, the light curve also shows features typical for other HW Vir binaries such as a secondary eclipse and strong reflection effect from the irradiated, cool companion. The orbital period is 0.127037 days (~3 hr), falling right at the peak of the orbital period distribution of known HW Vir systems. Analysis of our time-series spectroscopy yields a radial velocity semiamplitude of KsdB = 100.0 ± 2.0 km s-1, which is among the fastest line-of-sight velocities found to date for an HW Vir binary. State-of-the-art atmospheric models that account for deviations from local thermodynamic equilibrium are used to determine the atmospheric parameters of the sdB. Although we cannot claim a unique light-curve modeling solution, the best-fitting model has an sdB mass of MsdB = 0.47 ± 0.03 M⊙ and a companion mass of MdM = 0.18 ± 0.01 M⊙. The radius of the companion appears to be inflated relative to theoretical mass-radius relationships, consistent with other known HW Vir binaries. Additionally, the M dwarf is one of the most massive found to date among this type of binary.

Keywords: eclipsing binary stars; fundamental parameters of stars; b subdwarf stars
High-energy Neutrinos from Gamma-Ray-faint Accretion-powered Hypernebulae

Hypernebulae are inflated by accretion-powered winds accompanying hyper-Eddington mass transfer from an evolved post-main-sequence star onto a black hole or neutron star companion. The ions accelerated at the termination shock-where the collimated fast disk winds and/or jet collide with the slower, wide-angled wind-fed shell-can generate high-energy neutrinos via hadronic proton-proton reactions, and photohadronic (p γ) interactions with the disk thermal and Comptonized nonthermal background photons. It has been suggested that some fast radio bursts (FRBs) may be powered by such short-lived jetted hyper-accreting engines. Although neutrino emission associated with the millisecond duration bursts themselves is challenging to detect, the persistent radio counterparts of some FRB sources-if associated with hypernebulae-could contribute to the high-energy neutrino diffuse background flux. If the hypernebula birth rate follows that of stellar-merger transients and common envelope events, we find that their volume-integrated neutrino emission-depending on the population-averaged mass-transfer rates-could explain up to ~25% of the high-energy diffuse neutrino flux observed by the IceCube Observatory and the Baikal Gigaton Volume Detector Telescope. The time-averaged neutrino spectrum from hypernebula-depending on the population parameters-can also reproduce the observed diffuse neutrino spectrum. The neutrino emission could in some cases furthermore extend to >100 PeV, detectable by future ultra-high-energy neutrino observatories. The large optical depth through the nebula to Breit-Wheeler (γ γ) interaction attenuates the escape of GeV-PeV gamma rays coproduced with the neutrinos, rendering these gamma-ray-faint neutrino sources, consistent with the Fermi observations of the isotropic gamma-ray background.

Keywords: neutrino astronomy; high energy astrophysics; shocks; x-ray binary stars; ultraluminous x-ray sources; nebulae; compact nebulae; jets; particle astrophysics; plasma astrophysics; high mass x-ray binary stars; binary stars
A Candle in the Wind: A Radio Filament in the Core of the A3562 Galaxy Cluster

Using a MeerKAT observation of the galaxy cluster A3562 (a member of the Shapley supercluster), we have discovered a narrow, long and straight, very faint radio filament, which branches out at a straight angle from the tail of a radio galaxy located in projection near the core of the cluster. The radio filament spans 200 kpc and aligns with a sloshing cold front seen in the X-rays, staying inside the front in projection. The radio spectral index along the filament appears uniform (within large uncertainties) at α ≃ -1.5. We propose that the radio galaxy is located outside the cold front but dips its tail under the front. The tangential wind that blows there may stretch the radio plasma from the radio galaxy into a filamentary structure. Some reacceleration is needed in this scenario to keep the radio spectrum uniform. Alternatively, the cosmic-ray electrons from that spot in the tail can spread along the cluster magnetic field lines, straightened by that same tangential flow, via anomalously fast diffusion. Our radio filament can provide constraints on this process. We also uncover a compact radio source at the brightest cluster galaxy that is 2-3 orders of magnitude less luminous than those in typical cluster central galaxies-probably an example of a brightest cluster galaxy starved of accretion fuel by gas sloshing.

Keywords: galaxy clusters; radio galaxies; intracluster medium; tailed radio galaxies; radio continuum emission; extragalactic radio sources
Testing the Strong Equivalence Principle. II. Relating the External Field Effect in Galaxy Rotation Curves to the Large-scale Structure of the Universe

Theories of modified gravity generically violate the strong equivalence principle, so that the internal dynamics of a self-gravitating system in freefall depends on the strength of the external gravitational field (the external field effect). We fit rotation curves (RCs) from the SPARC database with a model inspired by Milgromian dynamics (MOND), which relates the outer shape of an RC to the external Newtonian field from the large-scale baryonic matter distribution through a dimensionless parameter eN. We obtain a > 4σ statistical detection of the external field effect (i.e. eN > 0 on average), confirming previous results. We then locate the SPARC galaxies in the cosmic web of the nearby universe and find a striking contrast in the fitted eN values for galaxies in underdense versus overdense regions. Galaxies in an underdense region between 22 and 45 Mpc from the celestial axis in the northern sky have RC fits consistent with eN ≃ 0, while those in overdense regions adjacent to the CfA2 Great Wall and the Perseus-Pisces Supercluster return eN that are a factor of two larger than the median for SPARC galaxies. We also calculate independent estimates of eN from galaxy survey data and find that they agree with the eN inferred from the RCs within the uncertainties, the chief uncertainty being the spatial distribution of baryons not contained in galaxies or clusters.

Keywords: non-standard theories of gravity; modified newtonian dynamics; gravitation; disk galaxies
New Type Ia Supernova Yields and the Manganese and Nickel Problems in the Milky Way and Dwarf Spheroidal Galaxies

In our quest to identify the progenitors of Type Ia supernovae (SNe Ia), we first update the nucleosynthesis yields for both near-Chandrasekhar- (Ch) and sub-Ch-mass white dwarfs (WDs) for a wide range of metallicities with our 2D hydrodynamical code and the latest nuclear reaction rates. We then include the yields in our galactic chemical evolution code to predict the evolution of elemental abundances in the solar neighborhood and dwarf spheroidal (dSph) galaxies Fornax, Sculptor, Sextans, and Carina. In the observations of the solar neighborhood stars, Mn shows an opposite trend to α elements, showing an increase toward higher metallicities, which is very well reproduced by the deflagration-detonation transition of Ch-mass WDs but never by double detonations of sub-Ch-mass WDs alone. The problem of Ch-mass SNe Ia was the Ni overproduction at high metallicities. However, we found that Ni yields of Ch-mass SNe Ia are much lower with the solar-scaled initial composition than in previous works, which keeps the predicted Ni abundance within the observational scatter. From the evolutionary trends of elemental abundances in the solar neighborhood, we conclude that the contribution of sub-Ch-mass SNe Ia to chemical enrichment is up to 25%. In dSph galaxies, however, larger enrichment from sub-Ch-mass SNe Ia than in the solar neighborhood may be required, which causes a decrease in [(Mg, Cr, Mn, Ni)/Fe] at lower metallicities. The observed high [Mn/Fe] ratios in Sculptor and Carina may also require additional enrichment from pure deflagrations, possibly as SNe Iax. Future observations of dSph stars will provide more stringent constraints on the progenitor systems and explosion mechanism of SNe Ia.

Keywords: type ia supernovae; supernovae; nucleosynthesis; explosive nucleosynthesis; chemical abundances; galaxy chemical evolution; dwarf spheroidal galaxies; sculptor dwarf elliptical galaxy; fornax dwarf spheroidal galaxy
Identifying and Repairing Catastrophic Errors in Galaxy Properties Using Dimensionality Reduction

Our understanding of galaxy evolution is derived from large surveys designed to maximize efficiency by only observing the minimum amount needed to infer properties for a typical galaxy. However, for a few percent of galaxies in every survey, these observations are insufficient and derived properties can be catastrophically wrong. Further, it is currently difficult or impossible to determine which objects have failed, so that these contaminate every study of galaxy properties. We develop a novel method to identify these objects by combining the astronomical codes that infer galaxy properties with the dimensionality reduction algorithm t-SNE, which groups similar objects to determine which inferred properties are out of place. This method provides an improvement for the COSMOS catalog, which already uses existing techniques for catastrophic error removal, and therefore should improve the quality of large catalogs and any studies that are sensitive to large redshift errors.

Keywords: astronomy data analysis; redshift surveys; high-redshift galaxies; photometry; dimensionality reduction; galaxy properties
Discovery of the Longest-period Classical Cepheid in the Milky Way

We report the discovery of the classical Cepheid OGLE-GD-CEP-1884 (= GDS_J1535467-555656) with the longest pulsation period known in our Galaxy. The period of 78.14 days is nearly 10 days longer than that of the previous record-holding Cepheid, S Vulpeculae, and thus, OGLE-GD-CEP-1884 can be categorized as the first ultra-long-period Cepheid in the Milky Way. This star is present in the ASAS-SN and Gaia DR3 catalogs of variable stars, but it has been classified as a long-period variable in those catalogs. Based on more than 10 yr of the photometric monitoring of this star carried out by the OGLE project in the I and V bands and a radial velocity curve from the Gaia Focused Product Release, we unequivocally demonstrate that this object is a fundamental-mode classical Cepheid. By employing the mid-infrared period–luminosity relation, we determine the distance to OGLE-GD-CEP-1884 (4.47 ± 0.34 kpc) and place it on the Milky Way map, along with about 2400 other classical Cepheids. We also discuss the potential of finding additional ultra-long-period Cepheids in our Galaxy.

Keywords: cepheid variable stars; delta cepheid variable stars; cepheid distance
Long-term Stability of Six Neptunian Trojans

This paper explores the long-term stability of six Neptunian Trojans. In contrast with other Neptunian Trojans, these objects have previously unknown lifetimes and larger orbital uncertainties due to their shorter observational arcs. We obtained new astrometry of the six Trojans using the Magellan telescope, refit their orbits, and performed Gyr-long numerical integrations to estimate their lifetimes. The results show that five of these six objects are stable over Gyr timescales. The remaining object, 2015 VV165, has a calculated lifetime of 0.691 ± 0.001 Gyr, which is similar to the previous estimate of 0.65 Gyr. As a result, the shorter lifetime of this latter object is most likely physical (rather than due to uncertainties in its orbital determination).

Keywords: solar system; small solar system bodies; trans-neptunian objects; neptune trojans; trojan asteroids
The Global Stability of M33 in MOND

The dynamical stability of disk galaxies is sensitive to whether their anomalous rotation curves are caused by dark matter halos or Milgromian dynamics (MOND). We investigate this by setting up a MOND model of M33. We first simulate it in isolation for 6 Gyr, starting from an initial good match to the rotation curve (RC). Too large a bar and bulge form when the gas is too hot, but this is avoided by reducing the gas temperature. A strong bar still forms in 1 Gyr, but rapidly weakens and becomes consistent with the observed weak bar. Previous work showed this to be challenging in Newtonian models with a live dark matter halo, which developed strong bars. The bar pattern speed implies a realistic corotation radius of 3 kpc. However, the RC still rises too steeply, and the central line-of-sight velocity dispersion (LOSVD) is too high. We then add a constant external acceleration field of 8.4 × 10-12 m s-2 at 30° to the disk as a first-order estimate for the gravity exerted by M31. This suppresses buildup of material at the center, causing the RC to rise more slowly and reducing the central LOSVD. Overall, this simulation bears good resemblance to several global properties of M33, and highlights the importance of including even a weak external field on the stability and evolution of disk galaxies. Further simulations with a time-varying external field, modeling the full orbit of M33, will be needed to confirm its resemblance to observations.

Keywords: modified newtonian dynamics; triangulum galaxy; barred spiral galaxies; hydrodynamical simulations; stellar dynamics; galaxy evolution
A First Look at the Abundance Pattern-O/H, C/O, and Ne/O-in z > 7 Galaxies with JWST/NIRSpec

We analyze the rest-frame near-UV and optical nebular spectra of three z > 7 galaxies from the Early Release Observations taken with the Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). These three high-z galaxies show the detection of several strong emission nebular lines, including the temperature-sensitive [O III] λ4363 line, allowing us to directly determine the nebular conditions and abundances for O/H, C/O, and Ne/O. We derive O/H abundances and ionization parameters that are generally consistent with other recent analyses. We analyze the mass-metallicity relationship (i.e., slope) and its redshift evolution by comparing between the three z > 7 galaxies and local star-forming galaxies. We also detect the C III] λλ1907, 1909 emission in a z > 8 galaxy from which we determine the most distant C/O abundance to date. This valuable detection of log(C/O) = -0.83 ± 0.38 provides the first test of C/O redshift evolution out to high redshift. For neon, we use the high-ionization [Ne III] λ3869 line to measure the first Ne/O abundances at z > 7, finding no evolution in this α-element ratio. We explore the tentative detection of [Fe II] and [Fe III] lines in a z > 8 galaxy, which would indicate a rapid buildup of metals. Importantly, we demonstrate that properly flux-calibrated and higher-S/N spectra are crucial to robustly determine the abundance pattern in z > 7 galaxies with NIRSpec/JWST.

Keywords: galaxy chemical evolution; emission line galaxies; cosmic abundances; metallicity
A Stellar Activity F-statistic for Exoplanet Surveys (SAFE)

In the search for planets orbiting distant stars, the presence of stellar activity in the atmospheres of observed stars can obscure the radial velocity signal used to detect such planets. Furthermore, this stellar activity contamination is set by the star itself and cannot simply be avoided with better instrumentation. Various stellar activity indicators have been developed that may correlate with this contamination. We introduce a new stellar activity indicator called the Stellar Activity F-statistic for Exoplanet surveys (SAFE) that has higher statistical power (i.e., probability of detecting a true stellar activity signal) than many traditional stellar activity indicators in a simulation study of an active region on a Sun-like star with a moderate-to-high signal-to-noise ratio. Also through simulation, the SAFE is demonstrated to be associated with the projected area on the visible side of the star covered by active regions. We also demonstrate that the SAFE detects statistically significant stellar activity in most of the spectra for HD 22049, a star known to have high stellar variability. Additionally, the SAFE is calculated for recent observations of the three low-variability stars HD 34411, HD 10700, and HD 3651, the latter of which is known to have a planetary companion. As expected, the SAFE for these three only occasionally detects activity. Furthermore, initial exploration appears to indicate that the SAFE may be useful for disentangling stellar activity signals from planet-induced Doppler shifts.

Keywords: exoplanet detection methods; radial velocity; stellar activity; linear regression; astrostatistics; doppler shift; principal component analysis; parametric hypothesis tests; exoplanet astronomy; exoplanets; starspots
Neon Abundances of B Stars in the Solar Neighborhood

We constructed a comprehensive model atom for Ne I-Ne II using the most-up-to-date atomic data available and evaluated the nonlocal thermodynamic equilibrium (NLTE) line formation for Ne I and Ne II in classical 1D models representing the atmospheres of B-type stars. We find that the large NLTE strengthening of the Ne I lines corresponding to the 2p53p-2p53s transition array occurs due to extremely small photoionization cross sections of the 2p53s levels that lead to strong overpopulation of these levels relative to their LTE populations. The deviations from LTE for most Ne II lines are small and do not exceed 0.11 dex in absolute value. We analyzed 20 lines of Ne I and 13 lines of Ne II for 24 B-type stars in the temperature range of 10,400 ≤ ${T}_{\mathrm{eff}}$ ≤ 33,400 K. For five stars, the NLTE leads to consistent abundances of Ne I and Ne II, while the difference in LTE abundance can reach up to 0.50 dex. Using the experimental oscillator strengths recently measured by Piracha et al. leads to smaller line-by-line scatter for most of the investigated stars. The average neon abundance in 24 B-type stars in the solar neighborhood is 8.02 ± 0.05. This value may provide indirect constraints on the solar photospheric neon abundance.

Keywords: b stars; early-type stars; solar neighborhood; stellar abundances; chemical abundances; solar abundances
The Impact of Type Ia Supernovae in Quiescent Galaxies. II. Energetics and Turbulence

Type Ia supernovae (SNe Ia) provide unique and important feedback in quiescent galaxies, but their impact has been underappreciated. In this paper, we analyze a series of high-resolution simulations to examine the energetics and turbulence of the medium under SNe Ia. We find that when SN remnants are resolved, their effects differ distinctly from a volumetric heating term, as is commonly assumed in unresolved simulations. First, the net heating is significantly higher than expected, by 30 ± 10% per cooling time. This is because a large fraction of the medium is pushed into lower densities, which cool inefficiently. Second, the medium is turbulent; the root-mean-squared (rms) velocity of the gas to 20-50 km s-1 on a driving scale of tens of parsecs. The velocity field of the medium is dominated by compressional modes, which are larger than the solenoidal components by a factor of 3-7. Third, the hot gas has a very broad density distribution. The ratio between the density fluctuations and the rms Mach number, parameterized as b, is 2-20. This is in contrast to previous simulations of turbulent media, which have found b ≲ 1. The difference is mainly caused by the localized heating of SNe Ia, which creates a large density contrast. Last, the typical length scale of a density fluctuation grows with time, forming increasingly larger bubbles and filamentary ridges. These underlying density fluctuations need to be included when X-ray observations are interpreted.

Keywords: interstellar medium; type ia supernovae; elliptical galaxies; galaxy formation; galaxy evolution; hydrodynamical simulations; shocks; hot ionized medium
A Gaia-based Photometric and Kinematic Analysis of the Old Open Cluster King 11

This paper presents an investigation of an old age open cluster King 11 using Gaia's Early Data Release 3 data. Considering the stars with membership probability (Pμ) > 90%, we identified 676 most probable cluster members within the cluster's limiting radius. The mean proper motion for King 11 is determined as: μx = - 3.391 ± 0.006 and μy = - 0.660 ± 0.004 mas yr-1. The blue straggler stars of King 11 show a centrally concentrated radial distribution. The values of limiting radius, age, and distance are determined as 18'51, 3.63 ± 0.42 Gyr, and 3.33 ± 0.15 kpc, respectively. The cluster's apex coordinates (A = 267°84 ± 1°01, D = - 27°48 ± 1°03) are determined using the apex diagram method and verified using the (μU, μT) diagram. We also obtained the orbit that the cluster follows in the Galaxy and estimated its tentative birthplace in the disk. The resulting spatial velocity of King 11 is 60.2 ± 2.16 km s-1. A significant oscillation along the Z coordinate up to 0.556 ± 0.022 kpc is determined.

Keywords: hertzsprung russell diagram; open star clusters; astrometry; stellar kinematics; apex; orbits
Probing Dark Energy and Modifications of Gravity with Ground-based millimeter-wavelength Line Intensity Mapping

Line intensity mapping (LIM) can provide a powerful means to constrain the theory of gravity and the nature of dark energy at low and high redshifts by mapping the large-scale structure over many redshift epochs. In this paper, we investigate the potential of the next generation ground-based millimeter-wavelength LIM surveys in constraining several models beyond ΛCDM, involving either a dynamic dark energy component or modifications of the theory of gravity. Limiting ourselves to two-point clustering statistics, we consider the measurements of auto-spectra of several CO rotational lines (from J = 2‑1 to J = 6‑5) and the [C II] fine structure line in the redshift range of 0.25 < z < 12. We consider different models beyond ΛCDM, each one with different signatures and peculiarities. Among them, we focus on Jordan–Brans–Dicke and axion-driven early dark energy models as examples of well-studied scalar-tensor theories acting at late and early times, respectively. Additionally, we consider three phenomenological models based on an effective description of gravity at cosmological scales. We show that LIM surveys deployable within a decade (with ∼108 spectrometer hours) have the potential to improve upon the current bounds on all considered models significantly. The level of improvements range from a factor of a few to an order of magnitude.

Keywords: scalar-tensor-vector gravity; non-standard theories of gravity; co line emission; line intensities