adsabs/SciX_UAT_keywords huggingface dataset:
Long-term Statistics of Pulsar Glitches Due to History-dependent Avalanches

Stress accumulation-relaxation meta-models of pulsar glitches make precise, microphysics-agnostic predictions of long-term glitch statistics, which can be falsified by existing and future timing data. Previous meta-models assume that glitches are triggered by an avalanche process, e.g., involving superfluid vortices, and that the probability density function (PDF) of the avalanche sizes is history independent and specified exogenously. Here, a recipe is proposed to generate the avalanche sizes endogenously in a history-dependent manner, by tracking the thresholds of occupied vortex pinning sites as a function of time. Vortices unpin spasmodically from sites with thresholds below a global, time-dependent stress and repin at sites with thresholds above the global stress, imbuing the system with long-term memory. The meta-model predicts PDFs, auto-, and cross-correlations for glitch sizes and waiting times, which are provisionally inconsistent with current observations, unlike some previous meta-models (e.g., state-dependent Poisson process), whose predictions are consistent. The theoretical implications are intriguing, albeit uncertain, because history-dependent avalanches embody faithfully the popular, idealized understanding in the literature of how vortex unpinning operates as a driven, stochastic process. The meta-model predicts aftershocks, which occur with larger than average sizes and longer than average waiting times after the largest, system-resetting glitches. This prediction will be tested, once more data are generated by the next generation of pulsar timing campaigns.

Keywords: astrostatistics; neutron stars; pulsars; stellar rotation
ALMA 50-parsec-resolution Imaging of Jet-ISM Interaction in the Lensed Quasar MG J0414+0534

We report our high-resolution (0.03 arcsec-0.07 arcsec) Atacama Large Millimeter/submillimeter Array (ALMA) imaging of the quadruply lensed radio-loud quasar MG J0414+0534 at redshift z = 2.639 in the continuum and the broad CO(11-10) line at ∼340 GHz. With the help of strong lensing magnification and ALMA's high resolution, we succeeded in resolving the jet/dust and CO gas in the quasar host galaxy, both extending up to ∼1 kpc, with a resolution of ∼50 pc for the first time. Both the continuum emission and the CO(11-10) line have a similar bimodal structure aligned with the quasar jets (∼200 pc) observed by Very Long Baseline Interferometry at 5 and 8.4 GHz. The CO gas in the vicinity of both the eastern and western jet components at the location of ∼80 pc from the quasar core are moving at high velocities, up to ±600 km s-1 relative to the core. The observed features show clear evidence of strong interaction between the jets and interstellar medium (ISM). High temperature and high-density environments in the ISM of the quasar host galaxy, as suggested from CO line ratios, also support this result. The small scale of the jets, the jet-ISM interaction, and the continuum spectral energy distribution of this source indicate that we are watching the infancy stage of quasar radio activity.

Keywords: radio loud quasars; radio jets; molecular clouds; strong gravitational lensing; interstellar medium
Evidence of Stellar Oscillations in the Post-common-envelope Binary Candidate ASASSN-V J205543.90+240033.5

ASASSN-V J205543.90+240033.5 (ASJ2055) is a possible post-common-envelope binary system. Its optical photometric data show an orbital variation of about 0.52 days and a fast period modulation of P 0 ~ 9.77 minutes, whose origin is unknown. In this Letter, we report evidence of the stellar oscillation of the companion star as the origin of the fast period modulation. We analyze the photometric data taken by the Transiting Exoplanet Survey Satellite, the Liverpool Telescope, and the Lulin One-meter Telescope. It is found that the period of the 9.77 minutes signal measured in 2022 August is significantly shorter than that in 2021 July/August, and the magnitude of the change is of the order of ∣△P 0∣/P 0 ~ 0.0008(4). Such a large variation will be incompatible with the scenario of the white dwarf (WD) spin as the origin of the 9.77 minutes periodic modulation. We suggest that the fast periodic signal is related to the emission from the irradiated companion star rather than that of the WD. Using existing photometric data covering a wide wavelength range, we estimate that the hot WD in ASJ2055 has a temperature of T eff ~ 80,000 K and is heating the oscillating M-type main-sequence star with T eff ~ 3500 K on its unirradiated surface. The stellar oscillation of the M-type main-sequence star has been predicted in theoretical studies, but no observational confirmation has been done. ASJ2055, therefore, has the potential to be a unique laboratory for investigating the stellar oscillation of an M-type main-sequence star and the heating effect on stellar oscillation.

Keywords: binary stars; white dwarf stars
Interpreting the Si II and C II Line Spectra from the COS Legacy Archive Spectroscopic SurveY Using a Virtual Galaxy from a High-resolution Radiation-hydrodynamic Simulation

Observations of low-ionization state metal lines provide crucial insights into the interstellar medium (ISM) of galaxies, yet, disentangling the physical processes responsible for the emerging line profiles is difficult. This work investigates how mock spectra generated using a single galaxy in a radiation-hydrodynamical simulation can help us interpret observations of a real galaxy. We create 22,500 C II and Si II spectra from the virtual galaxy at different times and through multiple lines of sight and compare them with the 45 observations of low-redshift star-forming galaxies from the COS Legacy Spectroscopic SurveY (CLASSY). We find that the mock profiles provide accurate replicates of the observations of 38 galaxies with a broad range of stellar masses (106-109 M ⊙) and metallicities (0.02-0.55 Z ⊙). Additionally, we highlight that aperture losses explain the weakness of the fluorescent emission in several CLASSY spectra and must be accounted for when comparing simulations to observations. Overall, we show that the evolution of a single simulated galaxy can produce a large diversity of spectra whose properties are representative of galaxies of comparable or smaller masses. Building upon these results, we explore the origin of the continuum, residual flux, and fluorescent emission in the simulation. We find that these different spectral features all emerge from distinct regions in the galaxy's ISM, and their characteristics can vary as a function of the viewing angle. While these outcomes challenge simplified interpretations of down-the-barrel spectra, our results indicate that high-resolution simulations provide an optimal framework to interpret these observations.

Keywords: ultraviolet astronomy; interstellar medium; starburst galaxies
Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations

We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ2(k = 0.34 h Mpc-1) ≤ 457 mK2 at z = 7.9 and that Δ2(k = 0.36 h Mpc-1) ≤ 3496 mK2 at z = 10.4, an improvement by a factor of 2.1 and 2.6, respectively. These limits are mostly consistent with thermal noise over a wide range of k after our data quality cuts, despite performing a relatively conservative analysis designed to minimize signal loss. Our results are validated with both statistical tests on the data and end-to-end pipeline simulations. We also report updated constraints on the astrophysics of reionization and the cosmic dawn. Using multiple independent modeling and inference techniques previously employed by HERA Collaboration, we find that the intergalactic medium must have been heated above the adiabatic cooling limit at least as early as z = 10.4, ruling out a broad set of so-called "cold reionization" scenarios. If this heating is due to high-mass X-ray binaries during the cosmic dawn, as is generally believed, our result's 99% credible interval excludes the local relationship between soft X-ray luminosity and star formation and thus requires heating driven by evolved low-metallicity stars.

Keywords: astronomy data analysis; radio interferometers; intergalactic medium; reionization; galaxy formation; cosmology
Primordial Orbital Alignment of Sednoids

We examined the past history of the three most detached trans-Neptunian objects (TNOs)—Sedna, 2012 VP113, and Leleakuhonua (2015 TG387)—the three clearest members of the dynamical class known as sednoids, with high perihelia distances q. By integrating backward their nominal (and a set of cloned) orbits for the solar system's age, we surprisingly find that the only time all their apsidal lines tightly cluster was 4.5 Gyr ago, at perihelion longitude ϖ of 200°. This "primordial alignment" is independent of the observational biases that contribute to the current on-sky clustering in the large-semimajor-axis Kuiper Belt. If future sednoid discoveries confirm these findings, this strongly argues for an initial event during the planet formation epoch, which imprinted this particular apsidal orientation on the early detached TNO population. Their apsidal orientations were then subsequently modified only by the simple precession from the four giant planets (and weakly by the galactic tide). If other sednoids also cluster around the same primordial value, various models suggesting a still present planet in the outer solar system would be incompatible with this alignment. We inspected two scenarios that could potentially explain the primordial alignment. First, a rogue planet model (where another massive planet raises perihelia near its own longitude until ejection) naturally produces this signature. Alternatively, a close stellar passage early in solar system history raises perihelia, but it is poor at creating strong apsidal clustering. We show that all other known 35 < q < 55 au TNOs are either too perturbed or orbits are still too uncertain to provide evidence for or against this paradigm.

Keywords: trans-neptunian objects; kuiper belt; celestial mechanics
An Episode of Occultation Events in Gaia21bcv

A previously unremarkable star near the Canis Major OB1/R1 association underwent an episode of multiple deep brightness minima. Light curves based on archival Gaia, Zwicky Transient Facility (ZTF), and NEOWISE data and additional observations from the Las Cumbres Observatory and UKIRT show that the star was not variable prior to 2019 August 18 (MJD 58700), and on that date started showing brightness dips of up to 3 mag in the Gaia G and ZTF r bandpasses. After MJD 59500, ≈800 days after the onset of these dipping events, the star returned to its previous brightness, and no significant dipping events have been recorded since. Compared to the stable phase, NEOWISE IR photometry in the W1 and W2 bands indicates a generally redder color, and both decreases and increases in brightness at different times during the dipping episode. The spectrum of Gaia21bcv taken after the end of the dipping episode shows several neutral and ionized metal absorption lines, including Li, indicating a spectral type of ≈K5. Variable emission from [O I] was observed. The Hα absorption in Gaia21bcv is too faint and irregular for this spectral type, indicating that the line is partly filled in by variable emission, a signature of weak episodic accretion. Gaia21bcv lies above the zero-age main sequence, but is much fainter than typical R CrB stars. We interpret the light curve of Gaia21bcv as being similar to the occultation events in ϵ Aurigae, i.e., occultation by a disk around a companion object orbiting the primary star.

Keywords: pre-main sequence stars; debris disks; occulting disks; transits
NGC 6153: Reality is Complicated

We study the kinematics of emission lines that arise from many physical processes in NGC 6153 based upon deep, spatially resolved, high-resolution spectra acquired with the UVES spectrograph at the European Southern Observatory Very Large Telescope. Our most basic finding is that the plasma in NGC 6153 is complex, especially its temperature structure. The kinematics of most emission lines defines a classic expansion law, with the outer part expanding fastest (normal nebular plasma). However, the permitted lines of O I, C II, N II, O II, and Ne II present a constant expansion velocity that defines a second kinematic component (additional plasma component). The physical conditions imply two plasma components, with the additional plasma component having lower temperature and higher density. The [O II] density and the [N II] temperature are anomalous, but may be understood considering the contribution of recombination to these forbidden lines. The two plasma components have very different temperatures. The normal nebular plasma appears to have temperature fluctuations in part of its volume (main shell), but only small fluctuations elsewhere. The additional plasma component contains about half of the mass of the N2+ and O2+ ions, but only 3%-5% of the mass of H+ ions, so the two plasma components have very different chemical abundances. We estimate abundances of $12+\mathrm{log}({{\rm{O}}}^{2+}/{{\rm{H}}}^{+})\sim 9.2$ dex and He/H ~ 0.13. Although they are all complications, multiple plasma components, temperature fluctuations, and the contributions of multiple physical processes to a given emission line are all part of the reality in NGC 6153, and should generally be taken into account. *Based on observations collected at the European Southern Observatory under ESO program(s) 69.D-0174(A).

Keywords: stellar evolution; interstellar medium; planetary nebulae; spectroscopy; astronomical techniques; chemical abundances; cosmic abundances
The Deformation of an Erupting Magnetic Flux Rope in a Confined Solar Flare

Magnetic flux ropes (MFRs), sets of coherently twisted magnetic field lines, are believed as core structures of various solar eruptions. Their evolution plays an important role to understand the physical mechanisms of solar eruptions, and can shed light on adverse space weather near the Earth. However, the erupting MFRs are occasionally prevented by strong overlying magnetic fields, and the MFR evolution during the descending phase in the confined cases is lacking attention. Here, we present the deformation of an erupting MFR accompanied by a confined double-peaked solar flare. The first peak corresponded to the MFR eruption in a standard flare model, and the second peak was closely associated with the flashings of an underlying sheared arcade (SA), the reversal slipping motion of the L-shaped flare ribbon, the falling of the MFR, and the shifting of top of filament threads. All results suggest that the confined MFR eruption involved in two-step magnetic reconnection presenting two distinct episodes of energy release in the flare impulsive phase, and the latter magnetic reconnection between the confined MFR, and the underlying SA caused the deformation of the MFR. It is proposed that an intergrated evolution for confined MFR eruptions can compose of three stages: the eruption, the confinement, and the deformation.

Keywords: solar flares; solar activity; solar magnetic reconnection
A Systematic Search of Zwicky Transient Facility Data for Ultracompact Binary LISA-detectable Gravitational-wave Sources

Using photometry collected with the Zwicky Transient Facility, we are conducting an ongoing survey for binary systems with short orbital periods ( ${P}_{{\rm{b}}}\lt 1\,\mathrm{hr})$ with the goal of identifying new gravitational-wave sources detectable by the upcoming Laser Interferometer Space Antenna (LISA). We present a sample of 15 binary systems discovered thus far, with orbital periods ranging from 6.91 to 56.35 minutes. Of the 15 systems, seven are eclipsing systems that do not show signs of significant mass transfer. Additionally, we have discovered two AM Canum Venaticorum systems and six systems exhibiting primarily ellipsoidal variations in their lightcurves. We present follow-up spectroscopy and high-speed photometry confirming the nature of these systems, estimates of their LISA signal-to-noise ratios, and a discussion of their physical characteristics.

Keywords: compact binary stars; close binary stars; interacting binary stars; eclipsing binary stars; ellipsoidal variable stars; gravitational wave sources; white dwarf stars
In Search of Infall Motion in Molecular Clumps. III. HCO+ (1-0) and H13CO+ (1-0) Mapping Observations toward Confirmed Infall Sources

The study of infall motion helps us to understand the initial stages of star formation. In this paper, we use the IRAM 30 m telescope to make mapping observations of 24 infall sources confirmed in previous work. The lines we use to track gas infall motions are HCO+ (1-0) and H13CO+ (1-0). All 24 sources show HCO+ emissions, while 18 sources show H13CO+ emissions. The HCO+ integrated intensity maps of 17 sources show clear clumpy structures; for the H13CO+ line, 15 sources show clumpy structures. We estimated the column density of HCO+ and H13CO+ using the RADEX radiation transfer code, and the obtained [HCO+]/[H2] and [H13CO+]/[HCO+] of these sources are about 10-11-10-7 and 10-3-1, respectively. Based on the asymmetry of the line profile of the HCO+, we distinguish these sources: 19 sources show blue asymmetric profiles, and the other sources show red profiles or symmetric peak profiles. For eight sources that have double-peaked blue line profiles and signal-to-noise ratios greater than 10, the RATRAN model is used to fit their HCO+ (1-0) lines, and to estimate their infall parameters. The mean V in of these sources is 0.3-1.3 km s-1, and the ${\dot{M}}_{\mathrm{in}}$ is about 10-3-10-4 M ⊙ yr-1, which is consistent with the results of intermediate or massive star formation in previous studies. The V in estimated from the Myers model is 0.1-1.6 km s-1, and the ${\dot{M}}_{\mathrm{in}}$ is within 10-3-10-5 M ⊙ yr-1. In addition, some identified infall sources show other star-forming activities, such as outflows and maser emissions. Especially for those sources with a double-peaked blue asymmetric profile, most of them have both infall and outflow evidence.

Keywords: star formation; interstellar medium; molecular clouds; collapsing clouds
CEERS: 7.7 μm PAH Star Formation Rate Calibration with JWST MIRI

We test the relationship between UV-derived star formation rates (SFRs) and the 7.7 μm polycyclic aromatic hydrocarbon luminosities from the integrated emission of galaxies at z ∼ 0–2. We utilize multiband photometry covering 0.2–160 μm from the Hubble Space Telescope, CFHT, JWST, Spitzer, and Herschel for galaxies in the Cosmic Evolution Early Release Science (CEERS) Survey. We perform spectral energy distribution (SED) modeling of these data to measure dust-corrected far-UV (FUV) luminosities, L FUV, and UV-derived SFRs. We then fit SED models to the JWST/MIRI 7.7–21 μm CEERS data to derive rest-frame 7.7 μm luminosities, L 770, using the average flux density in the rest-frame MIRI F770W bandpass. We observe a correlation between L 770 and L FUV, where . L 770 diverges from this relation for galaxies at lower metallicities, lower dust obscuration, and for galaxies dominated by evolved stellar populations. We derive a "single-wavelength" SFR calibration for L 770 that has a scatter from model estimated SFRs (σ ΔSFR) of 0.24 dex. We derive a "multiwavelength" calibration for the linear combination of the observed FUV luminosity (uncorrected for dust) and the rest-frame 7.7 μm luminosity, which has a scatter of σ ΔSFR = 0.21 dex. The relatively small decrease in σ suggests this is near the systematic accuracy of the total SFRs using either calibration. These results demonstrate that the rest-frame 7.7 μm emission constrained by JWST/MIRI is a tracer of the SFR for distant galaxies to this accuracy, provided the galaxies are dominated by star formation with moderate-to-high levels of attenuation and metallicity.

Keywords: star formation; polycyclic aromatic hydrocarbons; james webb space telescope; hubble space telescope; galaxy evolution; infrared galaxies
AC Her: Evidence of the First Polar Circumbinary Planet

We examine the geometry of the post-asymptotic giant branch (AGB) star binary AC Her and its circumbinary disk. We show that the observations describe a binary orbit that is perpendicular to the disk with an angular momentum vector that is within 9° of the binary eccentricity vector, meaning that the disk is close to a stable polar alignment. The most likely explanation for the very large inner radius of the dust is a planet within the circumbinary disk. This is therefore both the first reported detection of a polar circumbinary disk around a post-AGB binary and the first evidence of a polar circumbinary planet. We consider the dynamical constraints on the circumbinary disk size and mass. The polar circumbinary disk feeds circumstellar disks with gas on orbits that are highly inclined with respect to the binary orbit plane. The resulting circumstellar disk inclination could be anywhere from coplanar to polar depending upon the competition between the mass accretion and binary torques.

Keywords: accretion; binary stars; hydrodynamics; exoplanet formation; post-asymptotic giant branch stars
Simulating the Fermi Bubbles as Forward Shocks Driven by AGN Jets

The Fermi bubbles are two giant bubbles in gamma-rays lying above and below the Galactic Center (GC). Despite numerous studies on the bubbles, their origin and emission mechanism remain elusive. Here we use a suite of hydrodynamic simulations to study the scenario where the cosmic rays (CRs) in the bubbles are mainly accelerated at the forward shocks driven by a pair of opposing jets from Sgr A*. We find that an active galactic nucleus (AGN) jet event that happened 5-6 Myr ago can naturally reproduce the bilobular morphology of the bubbles, and the postshock gas temperature in the bubbles is heated to ∼0.4 keV, consistent with recent X-ray observations. The forward shocks compress the hot halo gas, and at low latitudes, the compressed gas shows an X-shaped structure, naturally explaining the biconical X-ray structure in the ROSAT 1.5 keV map in both morphology and X-ray surface brightness. CR acceleration is most efficient in the head regions of the bubbles during the first 2 Myr. The opposing jets release a total energy of ∼1055 erg with an Eddington ratio of ∼10-3, which falls well in the range of the hot accretion flow mode for black holes. Our simulations further show that the forward shocks driven by spherical winds at the GC typically produce bubbles with much wider bases than observed and could not reproduce the biconical X-ray structure at low latitudes. This suggests that starburst or AGN winds are unlikely the origin of the bubbles in the shock scenario.

Keywords: gamma-rays; active galaxies; jets; galactic cosmic rays; galactic center; milky way galaxy; hydrodynamical simulations; shocks; galaxy jets; high energy astrophysics; black holes