adsabs/SciX_UAT_keywords huggingface dataset:
Very Slow Rotators from Tidally Synchronized Binaries

A recent examination of K2 lightcurves indicates that ∼15% of Jupiter Trojans have very slow rotation (spin periods Ps > 100 hr). Here we consider the possibility that these bodies formed as equal-size binaries in the massive outer disk at ∼20-30 au. Prior to their implantation as Jupiter Trojans, tight binaries tidally evolved toward a synchronous state with Ps ∼ Pb, where Pb is the binary orbit period. They may have been subsequently dissociated by impacts and planetary encounters with at least one binary component retaining its slow rotation. Surviving binaries on Trojan orbits would continue to evolve by tides and spin-changing impacts over 4.5 Gyr. To explain the observed fraction of slow rotators, we find that at least ∼15%-20% of outer disk bodies with diameters 15 < D < 50 km would have to form as equal-size binaries with 12 ≲ ab/R ≲ 30, where ab is the binary semimajor axis and R = D/2. The mechanism proposed here could also explain very slow rotators found in other small-body populations.

Keywords: kuiper belt; jupiter trojans; tidal interaction
Toward a Full MHD Jet Model of Spinning Black Holes. II. Kinematics and Application to the M87 Jet

In this paper, we investigate the magnetohydrodynamical structure of a jet powered by a spinning black hole, where electromagnetic fields and fluid motion are governed by the Grad-Shafranov equation and the Bernoulli equation, respectively. When a steady and axisymmetric jet structure is assumed, the global solution is uniquely determined with the prescribed plasma loading into the jet and the poloidal shape of the outmost magnetic field line. We apply this model to the jet in the center of the nearby radio galaxy M87, and we find that it can naturally explain the slow flow acceleration and the flow velocity stratification within 105 gravitational radii from the central black hole. In particular, we find that the extremal black hole spin is disfavored by the flow velocity measurements if the plasma loading into the jet is dominated by the electron-positron pair production at the jet base.

Keywords: magnetic fields; magnetohydrodynamics; black hole physics; galaxy jets; relativistic jets
Rotation Curve Measurement of Dark Matter Content of a z 0.5 Galaxy

Measurements of galaxy rotation curves provide direct measurements of the distribution of baryonic and dark matter in galaxies. Here, we present spectroscopic confirmation and one such rotation curve for a z = 0.5325 galaxy observed with Keck I/MOSFIRE as a filler target for the Web Epoch of Reionization Survey. The rotation curve was derived from Hα 6563 Å emission out to a galactocentric radius of approximately 24 kpc. The target's rotation curve is well fit by an arctangent curve, that when combined with broadbanned photometric constraints on the galaxy's stellar mass, predicts a dark matter fraction consistent with results from the literature for z ~ 0.5. We constrain the estimate for this galaxy's dark matter fraction to be 93%, out to a galactocentric radius of 30 kpc.

Keywords: galaxy dark matter halos; disk galaxies; galaxy rotation curves
Measurement of High-energy Cosmic-Ray Proton Spectrum from the ISS-CREAM Experiment

The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded data for 539 days from 2017 August to 2019 February. We report the energy spectrum of cosmic-ray protons from the ISS-CREAM experiment at energies from 1.60 × 103 to 6.55 × 105 GeV. The measured spectrum deviates from a single power law. A smoothly broken power-law fit to the data, including statistical and systematic uncertainties, shows the spectral index change at 9.0 × 103 GeV from 2.57 ± 0.03 to 2.82 ± 0.02 with a significance of greater than 3σ. This bump-like structure is consistent with a spectral softening recently reported by the balloon-borne CREAM, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies.

Keywords: galactic cosmic rays
Lepto-hadronic Interpretation of 2021 RS Ophiuchi Nova Outburst

Very-high-energy (VHE; 100 GeV < E ≤ 100 TeV) and high-energy (HE; 100 MeV < E ≤ 100 GeV) gamma rays were observed from the symbiotic recurrent nova RS Ophiuchi (RS Oph) during its outburst in 2021 August by various observatories, such as the High Energy Stereoscopic System (HESS), Major Atmospheric Gamma Imaging Cherenkov (MAGIC), and Fermi-Large Area Telescope (LAT). The models that have been explored so far tend to favor a hadronic scenario of particle acceleration over an alternative leptonic scenario. This paper explores a time-dependent lepto-hadronic scenario to explain the emission from the RS Oph source region. We have used simultaneous low-frequency radio data observed by various observatories along with the data provided by HESS, MAGIC, and Fermi-LAT to explain the multiwavelength spectral energy distributions corresponding to 4 days after the outburst. Our results show that a lepto-hadronic interpretation of the source not only explains the observed HE-VHE gamma-ray data but the corresponding model synchrotron component is also consistent with the first 4 days of low-radio-frequency data, indicating the presence of nonthermal radio emission at the initial stage of the nova outburst. We have also calculated the expected neutrino flux from the source region and discuss the possibility of detecting neutrinos.

Keywords: recurrent novae; symbiotic novae; gamma-ray sources; radio sources
Stability of C59 Knockout Fragments from Femtoseconds to Infinity

We have studied the stability of C59 anions as a function of time, from their formation on femtosecond timescales to their stabilization on second timescales and beyond, using a combination of theory and experiments. The ${{\rm{C}}}_{59}^{-}$ fragments were produced in collisions between C60 fullerene anions and neutral helium gas at a velocity of 90 km s‑1 (corresponding to a collision energy of 166 eV in the center-of-mass frame). The fragments were then stored in a cryogenic ion beam storage ring at the DESIREE facility, where they were followed for up to 1 minute. Classical molecular dynamics simulations were used to determine the reaction cross section and the excitation energy distributions of the products formed in these collisions. We find that about 15% of the ${{\rm{C}}}_{59}^{-}$ ions initially stored in the ring are intact after about 100 ms and that this population then remains intact indefinitely. This means that C60 fullerenes exposed to energetic atoms and ions, such as stellar winds and shock waves, will produce stable, highly reactive products, like C59, that are fed into interstellar chemical reaction networks.

Keywords: interstellar molecules; fullerenes; collision physics; ion-storage rings
The Iron Yield of Core-collapse Supernovae

We present a systematic analysis of 191 stripped-envelope supernovae (SE SNe), aimed at computing their 56Ni masses from the luminosity in their radioactive tails ( ${M}_{\mathrm{Ni}}^{\mathrm{tail}}$ ) and/or in their maximum light, and the mean 56Ni and iron yields of SE SNe and core-collapse SNe. Our sample consists of SNe IIb, Ib, and Ic from the literature and from the Zwicky Transient Facility Bright Transient Survey. To calculate luminosities from optical photometry, we compute bolometric corrections using 49 SE SNe with optical and near-IR photometry, and develop corrections to account for the unobserved UV and IR flux. We find that the equation of Khatami & Kasen for radioactive 56Ni-powered transients with a single free parameter does not fit the observed peak time-luminosity relation of SE SNe. Instead, we find a correlation between ${M}_{\mathrm{Ni}}^{\mathrm{tail}}$ , peak time, peak luminosity, and decline rate, which allows for measuring individual 56Ni masses to a precision of 14%. Applying this method to the whole sample, we find, for SNe IIb, Ib, and Ic, mean 56Ni masses of 0.066 ± 0.006, 0.082 ± 0.009, and 0.132 ± 0.011 M ⊙, respectively. After accounting for their relative rates, for SE SNe as a whole, we compute mean 56Ni and iron yields of 0.090 ± 0.005 and 0.097 ± 0.007 M ⊙, respectively. Combining these results with the recent Type II SN mean 56Ni mass derived by Rodríguez et al., core-collapse SNe, as a whole, have mean 56Ni and iron yields of 0.055 ± 0.006 and 0.058 ± 0.007 M ⊙, respectively. We also find that radioactive 56Ni-powered models typically underestimate the peak luminosity of SE SNe by 60%-70%, suggesting the presence of an additional power source contributing to the luminosity at peak.

Keywords: supernovae; core-collapse supernovae; type ii supernovae; type ib supernovae; type ic supernovae
Statistical Properties of Electron-scale Magnetic Peaks in the Solar Wind at 1 au

Energy cascade from magnetohydrodynamic to kinetic scales can create many coherent structures in the turbulent astrophysical plasma environment, such as magnetic holes and magnetic peaks. Knowing the properties of each coherent structure is critical to better understand the process of the energy cascade. Recently, electron-scale magnetic peaks (ESMPs) are revealed to exist in the solar wind at 1 au. Here, we investigate the properties of the ESMPs upstream of the terrestrial bow shock based on observations of the Magnetospheric Multiscale spacecraft. We regard an isolated ESMP or a train of ESMPs as an ESMP event, and 204 ESMPs or 32 ESMP events are found. Both the durations and cross-section sizes of the ESMPs obey log-normal distributions. The median duration and cross-section size are ~0.25 s and ~0.33 ion gyroradius, respectively. The ESMP event with an average occurrence rate of ~8.8 events per day tends to occur during the weak interplanetary magnetic field strength or the slow solar wind. We also find that the ion foreshock is an important source of the ESMP events, and a small part of the ESMP events originates from the upstream pristine solar wind. Although only 12 out of 204 ESMPs have bipolar electron velocities, we suggest that the electron vortex is an essential feature for the stable ESMP. The generation mechanism of the ESMPs is unclear; nevertheless, finding out the origin of the electron vortex in the ion foreshock might help to reveal their generation mechanism.

Keywords: solar wind; interplanetary magnetic fields
Return to the Forgotten Ultraluminous X-Ray Source: A Broadband NICER+NuSTAR Study of NGC 4190 ULX-1

We observed the nearby and relatively understudied ultraluminous X-ray source (ULX) NGC 4190 ULX-1 jointly with Neutron Star Interior Composition Explorer (NICER) and NuSTAR to investigate its broadband spectrum, timing properties, and spectral variation over time. We found NGC 4190 ULX-1 to have a hard spectrum characterized by two thermal components (with temperatures ∼0.25 and ∼1.6 keV) and a high-energy excess typical of the ULX population although the spectrum turns over at an unusually low energy. While no pulsations were detected (with pulsed fraction 3σ upper limits of 16% for NICER and 35% for NuSTAR), the source shows significant stochastic variability, and the covariance spectrum indicates the presence of a high-energy cutoff power-law component, potentially indicative of an accretion column. Additionally, when fitting archival XMM-Newton data with a similar model, we find that the luminosity–temperature evolution of the hot thermal component follows the behavior of a super-Eddington slim disk though the expected spectral broadening for such a disk is not seen, suggesting that the inner accretion disk may be truncated by a magnetic field. Therefore, despite the lack of detected pulsations, there is tantalizing evidence for NGC 4190 ULX-1 being a candidate neutron star accretor although further broadband observations will be required to confirm this behavior.

Keywords: ultraluminous x-ray sources; x-ray astronomy; accretion; neutron stars; compact objects; x-ray sources
Search for a Black Hole Binary in Gaia DR3 Astrometric Binary Stars with Spectroscopic Data

We report the discovery of a candidate binary system consisting of a black hole (BH) and a red giant branch star in Gaia DR3. This binary system was discovered from 64,108 binary solutions for which both astrometric and spectroscopic data are available. For this system, the astrometric and spectroscopic solutions are consistent with each other, making this system a confident candidate of a BH binary. The primary (visible) star in this system, Gaia DR3 5870569352746779008, is a red giant branch star whose mass is quite uncertain. Fortunately, despite the uncertainty of the primary's mass, we can estimate the mass of the secondary (dark) object in this system to be >5.68 M ⊙ with a probability of 99%, based on the orbital parameters. The mass of the secondary object is much larger than the maximum neutron star mass (~2.0 M ⊙), which indicates that the secondary object is likely a BH. We argue that, if this dark object is not a BH, this system must be a more exotic system, in which the primary red giant branch star orbits around a quadruple star system (or a higher-order multiple-star system) whose total mass is more than 5.68 M ⊙. If this is a genuine BH binary, this has the longest period (1352.22 ± 45.81 days) among those discovered so far. As our conclusion entirely relies on Gaia DR3 data, independent confirmation with follow-up observations (e.g., long-term time-series spectra) is desired.

Keywords: astrometric binary stars; spectroscopic binary stars; stellar mass black holes
A Timing View of the Additional High-energy Spectral Component Discovered in the Black Hole Candidate Swift J1727.8-1613

We present an energy-dependent analysis for the type-C quasiperiodic oscillations (QPOs) observed in the black hole X-ray binary Swift J1727.8–1613 using Insight-HXMT observations. We find that the QPO fractional rms at energies above 40 keV is significantly higher than that below 20 keV. This is the first report of a high energy (HE) rms excess in the rms spectrum of a black hole X-ray binary. In the high energy band, an extra hard component is observed in addition to the standard thermal Comptonization component at a similar energy band. The value of the QPO HE rms excess is not only correlated with the disk parameters and the photon index of the standard Comptonization component but also exhibits a moderate positive correlation with the flux of the additional hard spectral component. No features in the QPO phase-lag spectra are seen corresponding to the additional hard component. We propose that the additional hard component in the spectrum may originate from jet emission and the associated QPO HE rms excess can be explained by the precession of the jet base.

Keywords: low-mass x-ray binary stars; accretion; astrophysical black holes; stellar mass black holes
Searching for the Signal of a Primordial Black Hole from CMB Lensing and γ-Ray Emissions

In this letter, we search for the signal of primordial black holes (PBHs) by correlating the γ-ray emissions in the MeV energy band produced by the Hawking evaporation and the lensing effect of the cosmic microwave background (CMB). We use the conservative case of the astrophysical model as much as possible in the calculations, since the potential astrophysical origins dominate the observed emission in the MeV energy band. By carefully discussing the appropriate energy bands corresponding to different PBH masses, it is worth expecting a tight constraint on the fraction of the Schwarzschild PBHs in the mass range of 1016-5 × 1017 g by simulations of the sensitivity of the future CMB-S4 project and the γ-ray telescope e-ASTROGAM. Furthermore, we also consider the PBH model with spins and find that the constraining ability of the PBH fraction from the correlation between CMB lensing and γ-ray emissions can be improved by another order of magnitude, which could importantly fill the gaps with PBH fraction limits in the mass range of 5 × 1017-2 × 1018 g.

Keywords: primordial black holes; cosmic microwave background radiation; gamma-ray sources
HEROES: The Hawaii eROSITA Ecliptic Pole Survey Catalog

We present a seven-band (g, r, i, z, y, NB816, NB921) catalog derived from a Subaru Hyper Suprime-Cam (HSC) imaging survey of the North Ecliptic Pole (NEP). The survey, known as HEROES, consists of 44 deg2 of contiguous imaging reaching median 5σ depths of g: 26.5, r: 26.2, i: 25.7, z: 25.1, y: 23.9, NB816: 24.4, and NB921: 24.4 mag. We reduced these data with the HSC pipeline software hscPipe, and produced a resulting multiband catalog containing over 25 million objects. We provide the catalog in three formats: (1) a collection of hscPipe format forced photometry catalogs, (2) a single combined catalog containing every object in that data set with selected useful columns, and (3) a smaller variation of the combined catalog with only essential columns for basic analysis or low-memory machines. The catalog uses all the available HSC data on the NEP and may serve as the primary optical catalog for current and future NEP deep fields from instruments and observatories such as SCUBA-2, eROSITA, Spitzer, Euclid, and JWST.

Keywords: catalogs; galaxy counts; surveys; observational cosmology
Supernova Remnants in the Irregular Galaxy NGC 4449

The nearby irregular galaxy NGC 4449 has a star formation rate of ~0.4M ☉ yr-1 and should host of order 70 supernova remnants (SNRs) younger than 20,000 yr, a typical age for SNRs expanding into an interstellar medium (ISM) with a density of 1 cm-3 to reach the radiative phase. We have carried out an optical imaging and spectroscopic survey in an attempt to identify these SNRs. This task is challenging because diffuse gas with elevated ratios of [S II]:Hα is omnipresent in NGC 4449, causing confusion when using this common diagnostic for SNRs. Using narrowband interference-filter images, we first identified 49 objects that have elevated [S II]:Hα ratios compared to nearby H II regions. Using Gemini-N and GMOS, we then obtained high-resolution spectra of 30 of these SNR candidates, 25 of which have [S II]:Hα ratios greater than 0.5. Of these, 15 nebulae are almost certainly SNRs, based on a combination of characteristics: higher [O I]:Hα ratios and broader line widths than observed from H II regions. The remainder are good candidates as well, but need additional confirmation. Surprisingly, despite having superior imaging and spectroscopic data sets to examine, we are unable to confirm most of the candidates suggested by Leonidaki et al. While NGC 4449 is likely an extreme case because of the high surface brightness and elevated [S II]:Hα ratio of diffuse gas, it highlights the need for sensitive high-resolution optical spectroscopy, or high spatial resolution radio or X-ray observations that can ensure accurate SNR identifications in external galaxies.

Keywords: supernova remnants
First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way

We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), the Galactic center source associated with a supermassive black hole. These observations were conducted in 2017 using a global interferometric array of eight telescopes operating at a wavelength of λ = 1.3 mm. The EHT data resolve a compact emission region with intrahour variability. A variety of imaging and modeling analyses all support an image that is dominated by a bright, thick ring with a diameter of 51.8 ± 2.3 μas (68% credible interval). The ring has modest azimuthal brightness asymmetry and a comparatively dim interior. Using a large suite of numerical simulations, we demonstrate that the EHT images of Sgr A* are consistent with the expected appearance of a Kerr black hole with mass ~4 × 106 M ⊙, which is inferred to exist at this location based on previous infrared observations of individual stellar orbits, as well as maser proper-motion studies. Our model comparisons disfavor scenarios where the black hole is viewed at high inclination (i > 50°), as well as nonspinning black holes and those with retrograde accretion disks. Our results provide direct evidence for the presence of a supermassive black hole at the center of the Milky Way, and for the first time we connect the predictions from dynamical measurements of stellar orbits on scales of 103-105 gravitational radii to event-horizon-scale images and variability. Furthermore, a comparison with the EHT results for the supermassive black hole M87* shows consistency with the predictions of general relativity spanning over three orders of magnitude in central mass.

Keywords: black holes; kerr black holes; rotating black holes; heterodyne interferometry; galactic center
ASKAP-EMU Discovery of "Raspberry": A New Galactic SNR Candidate G308.73+1.38

We report the Australian Square Kilometre Array Pathfinder discovery of a new Galactic supernova remnant (SNR) candidate G308.73+1.38, which we name Raspberry. This new SNR candidate has an angular size of 20.'7 × 16.'7, and we measure a total integrated flux of 407 ± 50 mJy. We estimate Raspberry's most likely diameter of 10–30 pc which would place it at a distance 3–5 kpc, in the near side of the Milky Way's Scutum–Centaurus Arm. We also find a Stokes-V point source close to the center of Raspberry with a ∼5σ significance. This point source may be the remaining compact source, a neutron star, or possibly a pulsar, formed during the initial supernova event.

Keywords: supernova remnants; interstellar medium; radio continuum emission; milky way galaxy
A Generative Model for Realistic Galaxy Cluster X-Ray Morphologies

The X-ray morphologies of clusters of galaxies display significant variations, reflecting their dynamical histories and the nonlinear dependence of X-ray emissivity on the density of the intracluster gas. Qualitative and quantitative assessments of X-ray morphology have long been considered a proxy for determining whether clusters are dynamically active or "relaxed." Conversely, the use of circularly or elliptically symmetric models for cluster emission can be complicated by the variety of complex features realized in nature, spanning scales from megaparsecs down to the resolution limit of current X-ray observatories. In this work, we use mock X-ray images from simulated clusters from THE THREE HUNDRED project to define a basis set of cluster image features. We take advantage of the clusters' approximate self-similarity to minimize the differences between images before encoding the remaining diversity through a distribution of high-order polynomial coefficients. Principal component analysis then provides an orthogonal basis for this distribution, corresponding to natural perturbations from an average model. This representation allows novel, realistically complex X-ray cluster images to be easily generated, and we provide code to do so. The approach provides a simple way to generate training data for cluster image analysis algorithms and could be straightforwardly adapted to generate clusters displaying specific types of features or selected by physical characteristics available in the original simulations.

Keywords: galaxy clusters; intracluster medium
R-process Nucleosynthesis of Subminimal Neutron Star Explosions

We show that a minimum-mass neutron star undergoes delayed explosion after mass removal from its surface. We couple the Newtonian hydrodynamics to a nuclear reaction network of ~4500 isotopes to study the nucleosynthesis and neutrino emission during the explosion. An electron antineutrino burst with a peak luminosity of ~3 × 1050 erg s-1 is emitted while the ejecta is heated to ~109 K. A robust r-process nucleosynthesis is realized in the ejecta. Lanthanides and heavy elements near the second and third r-process peaks are synthesized as end products of nucleosynthesis, suggesting that subminimal neutron star explosions could be an important source of solar chemical elements.

Keywords: neutron stars; hydrodynamical simulations; neutrino astronomy; r-process; solar abundances