Sazuna/UAT_keywords huggingface dataset:
A Metallicity Dependence on the Occurrence of Core-collapse Supernovae. Core-collapse supernovae (CCSNe) are widely accepted to be caused by the explosive death of massive stars with initial masses ≳8 M ☉. There is, however, a comparatively poor understanding of how properties of the progenitors-mass, metallicity, multiplicity, rotation, etc.-manifest in the resultant CCSN population. Here, we present a minimally biased sample of nearby CCSNe from the All-Sky Automated Survey for Supernovae survey whose host galaxies were observed with integral-field spectroscopy using MUSE at the Very Large Telescope. This data set allows us to analyze the explosion sites of CCSNe within the context of global star formation properties across the host galaxies. We show that the CCSN explosion site oxygen abundance distribution is offset to lower values than the overall H II region abundance distribution within the host galaxies. We further split the sample at $12+{\mathrm{log}}_{10}({\rm{O}}/{\rm{H}})=8.6$ dex and show that within the subsample of low-metallicity host galaxies, the CCSNe unbiasedly trace the star formation with respect to oxygen abundance, while for the subsample of higher-metallicity host galaxies, they preferentially occur in lower-abundance star-forming regions. We estimate the occurrence of CCSNe as a function of oxygen abundance per unit star formation and show that there is a strong decrease as abundance increases. Such a strong and quantified metallicity dependence on CCSN production has not been shown before. Finally, we discuss possible explanations for our result and show that each of these has strong implications not only for our understanding of CCSNe and massive star evolution but also for star formation and galaxy evolution.

Keywords: Galaxy abundances, Supernovae, Core-collapse supernovae, Stellar evolution
Toward Microarcsecond Astrometry for the Innermost Wobbling Jet of the BL Lacertae Object OJ 287. The BL Lacertae object OJ 287 is a very unusual quasar producing a wobbling radio jet and some double-peaked optical outbursts with a possible period of about 12 yr for more than one century. This variability is widely explained by models of binary supermassive black holes (SMBHs) or precessing jets/disks from a single SMBH. To enable an independent and nearly bias-free investigation on these possible scenarios, we explored the feasibility of extremely high-precision differential astrometry on its innermost restless jet at millimeter wavelengths. Through revisiting some existing radio surveys and very long baseline interferometry (VLBI) data at frequencies from 1.4 to 15.4 GHz and performing new Very Long Baseline Array observations at 43.2 GHz, we find that the radio source J0854+1959, 7.'1 apart from OJ 287 and with no clearly seen optical and infrared counterparts, could provide a nearly ideal reference point to track the complicated jet activity of OJ 287. The source J0854+1959 has a stable GHz-peaked radio spectrum and shows a jet structure consisting of two discrete, milliarcsecond-scale-compact and steep-spectrum components and showing no proper motion over about 8 yr. The stable VLBI structure can be interpreted by an episodic, optically thin, and one-sided jet. With respect to its 4.1 mJy peak feature at 43.2 GHz, we have achieved an astrometric precision at the state-of-art level, about 10 μas. These results indicate that future VLBI astrometry on OJ 287 could allow us to accurately locate its jet apex and activity boundary, align its restless jet structure over decades without significant systematic bias, and probe various astrophysical scenarios.

Keywords: Radio continuum emission, Supermassive black holes, Very long baseline interferometry, Radio jets
Gear Up for the Action Replay: Leveraging Lensing for Enhanced Gravitational-wave Early Warning. Premerger gravitational-wave (GW) sky localization of binary neutron star (BNS) and neutron star-black hole (NSBH) coalescence events would enable telescopes to capture precursors and electromagnetic (EM) emissions around the time of the merger. We propose an astrophysical scenario that could provide early-warning times of hours to days before coalescence with subarcsecond localization, provided that these events are gravitationally lensed. The key idea is that if the BNS/NSBH is lensed, then so is the host galaxy identified via the EM counterpart. From the angular separation of the lensed host galaxy images, as well as its redshift and the (foreground) lens redshift, we demonstrate that, for galaxy-scale lenses, we can predict the time delays/arrival time differences assuming a standard lens model. We further assess the feasibility and benefits of lensing as a tool for early warning in various GW observing runs of the LIGO-Virgo-Kagra network, including Voyager and the third-generation network. To that end, we study the effect of the limited angular resolution of the telescopes on our ability to predict the time delays. We find that with an angular resolution of 0.05″ we can predict time delays of &gt;1 day with 1σ error bar of ${ \mathcal O }$ (hours) at best. We also construct realistic time delay distributions of detectable lensed BNSs/NSBHs to forecast the early-warning times we might expect in the observing scenarios we consider.

Keywords: Gravitational lensing, Gravitational waves
Correlating High-energy IceCube Neutrinos with 5BZCAT Blazars and RFC Sources. We investigate the possibility that blazars in the Roma-BZCAT Multifrequency Catalogue of Blazars (5BZCAT) are sources of the high-energy astrophysical neutrinos detected by the IceCube Neutrino Observatory, as recently suggested by Buson et al. Although we can reproduce their ~4.5σ result, which applies to 7 yr of neutrino data in the southern sky, we find no significant correlation with 5BZCAT sources when extending the search to the northern sky, where IceCube is most sensitive to astrophysical signals. To further test this scenario, we use a larger sample consisting of 10 yr of neutrino data recently released by the IceCube Collaboration, this time finding no significant correlation in neither the southern nor the northern sky. These results suggest that the strong correlation reported by Buson et al. using 5BZCAT could be due to a statistical fluctuation and possibly the spatial and flux nonuniformities in the blazar sample. We perform some additional correlation tests using the more uniform, flux-limited, and blazar-dominated Radio Fundamental Catalogue and find a ~3.2σ equivalent p-value when correlating it with the 7 yr southern neutrino sky. However, this correlation disappears completely when extending the analysis to the northern sky and when analyzing 10 yr of all-sky neutrino data. Our findings support a scenario where the contribution of the whole blazar class to the IceCube signal is relevant but not dominant, in agreement with most previous studies.

Keywords: Neutrino telescopes, Radio source catalogs, High energy astrophysics, Blazars, Neutrino astronomy, Cosmic ray astronomy, Active galactic nuclei
The Q Branch Cooling Anomaly Can Be Explained by Mergers of White Dwarfs and Subgiant Stars. Gaia's exquisite parallax measurements allowed for the discovery and characterization of the Q branch in the Hertzsprung-Russell diagram, where massive C/O white dwarfs (WDs) pause their dimming due to energy released during crystallization. Interestingly, the fraction of old stars on the Q branch is significantly higher than in the population of WDs that will become Q branch stars or that were Q branch stars in the past. From this, Cheng et al. inferred that ~6% of WDs passing through the Q branch experience a much longer cooling delay than that of standard crystallizing WDs. Previous attempts to explain this cooling anomaly have invoked mechanisms involving supersolar initial metallicities. In this paper, we describe a novel scenario in which a standard composition WD merges with a subgiant star. The evolution of the resulting merger remnant leads to the creation of a large amount of 26Mg, which, along with the existing 22Ne, undergoes a distillation process that can release enough energy to explain the Q branch cooling problem without the need for atypical initial abundances. The anomalously high number of old stars on the Q branch may thus be evidence that mass transfer from subgiants to WDs leads to unstable mergers.

Keywords: White dwarf stars, Cosmochronology, Binary stars, Nucleosynthesis
Signatures of the Self-organized Criticality Phenomenon in Precursors of Gamma-Ray Bursts. Precursors provide important clues to the nature of gamma-ray burst (GRB) central engines and can be used to contain GRB physical processes. In this Letter, we study the self-organized criticality in precursors of long GRBs in the third Swift/Burst Alert Telescope catalog. We investigate the differential and cumulative size distributions of 100 precursors, including peak flux, duration, rise time, decay time, and quiescent time with the Markov Chain Monte Carlo technique. It is found that all of the distributions can be well described by power-law models and understood within the physical framework of a self-organized criticality system. In addition, we inspect the cumulative distribution functions of the size differences with a q-Gaussian function. The scale-invariance structures of precursors further strengthen our findings. Particularly, similar analyses are made in 127 main bursts. The results show that both precursors and main bursts can be attributed to a self-organized criticality system with the spatial dimension S = 3 and driven by a similar magnetically dominated process.

Keywords: Gamma-ray bursts
Bursty Star Formation Naturally Explains the Abundance of Bright Galaxies at Cosmic Dawn. Recent discoveries of a significant population of bright galaxies at cosmic dawn $\left(z\gtrsim 10\right)$ have enabled critical tests of cosmological galaxy formation models. In particular, the bright end of the galaxys' UV luminosity functions (UVLFs) appear higher than predicted by many models. Using approximately 25,000 galaxy snapshots at 8 ≤ z ≤ 12 in a suite of FIRE-2 cosmological "zoom-in" simulations from the Feedback in Realistic Environments (FIRE) project, we show that the observed abundance of UV-bright galaxies at cosmic dawn is reproduced in these simulations with a multichannel implementation of standard stellar feedback processes, without any fine-tuning. Notably, we find no need to invoke previously suggested modifications, such as a nonstandard cosmology, a top-heavy stellar initial mass function, or a strongly enhanced star formation efficiency. We contrast the UVLFs predicted by bursty star formation in these original simulations to those derived from star formation histories (SFHs) smoothed over prescribed timescales (e.g., 100 Myr). The comparison demonstrates that the strongly time-variable SFHs predicted by the FIRE simulations play a key role in correctly reproducing the observed, bright-end UVLFs at cosmic dawn: the bursty SFHs induce order-or-magnitude changes in the abundance of UV-bright (M UV ≲ -20) galaxies at z ≳ 10. The predicted bright-end UVLFs are consistent with both the spectroscopically confirmed population and the photometrically selected candidates. We also find good agreement between the predicted and observationally inferred integrated UV luminosity densities, which evolve more weakly with redshift in FIRE than suggested by some other models.

Keywords: Galaxy formation, Star formation, High-redshift galaxies
DKIST Unveils the Serpentine Topology of Quiet Sun Magnetism in the Photosphere. We present the first quiet Sun spectropolarimetric observations obtained with the Visible SpectroPolarimeter at the 4 m Daniel K. Inouye Solar Telescope. We recorded observations in a wavelength range that includes the magnetically sensitive Fe I 6301.5/6302.5 Å doublet. With an estimated spatial resolution of 0.″08, this represents the highest spatial resolution full-vector spectropolarimetric observations ever obtained of the quiet Sun. We identified 53 small-scale magnetic elements, including 47 magnetic loops and four unipolar magnetic patches, with linear and circular polarization detected in all of them. Of particular interest is a magnetic element in which the polarity of the magnetic vector appears to change three times in only 400 km and which has linear polarization signals throughout. We find complex Stokes V profiles at the polarity inversion lines of magnetic loops and discover degenerate solutions, as we are unable to conclusively determine whether these arise due to gradients in the atmospheric parameters or smearing of opposite-polarity signals. We analyze a granule that notably has linear and circular polarization signals throughout, providing an opportunity to explore its magnetic properties. On this small scale, we see the magnetic field strength range from 25 G at the granular boundary to 2 kG in the intergranular lane (IGL) and sanity-check the values with the weak and strong field approximations. A value of 2 kG in the IGL is among the highest measurements ever recorded for the internetwork.

Keywords: Spectropolarimetry, Solar photosphere, Quiet sun, The Sun, Solar physics, Solar magnetic fields
Early Time Spectropolarimetry of the Aspherical Type II Supernova SN 2023ixf. We present six epochs of optical spectropolarimetry of the Type II supernova (SN) 2023ixf ranging from ~2 to 15 days after the explosion. Polarimetry was obtained with the Kast double spectrograph on the Shane 3 m telescope at Lick Observatory, representing the earliest such observations ever captured for an SN. We observe a high continuum polarization p cont ≈ 1% on days +1.4 and +2.5 before dropping to 0.5% on day +3.5, persisting at that level up to day +14.5. Remarkably, this change coincides temporally with the disappearance of highly ionized "flash" features. The decrease of the continuum polarization is accompanied by a ~70° rotation of the polarization position angle (PA) as seen across the continuum. The early evolution of the polarization may indicate different geometric configurations of the electron-scattering atmosphere as seen before and after the disappearance of the emission lines associated with highly ionized species (e.g., He II, C IV, and N III), which are likely produced by elevated mass loss shortly prior to the SN explosion. We interpret the rapid change of polarization and PA from days +2.5 to +4.5 as the time when the SN ejecta emerge from the dense asymmetric circumstellar material (CSM). The temporal evolution of the continuum polarization and the PA is consistent with an aspherical SN explosion that exhibits a distinct geometry compared to the CSM. The rapid follow-up spectropolarimetry of SN 2023ixf during the shock ionization phase reveals an exceptionally asymmetric mass-loss process leading up to the explosion.

Keywords: Spectropolarimetry, Core-collapse supernovae, Type II supernovae, Flash spectra, Circumstellar matter
Self-similar Outflows at the Source of the Fast Solar Wind: A Smoking Gun of Multiscale Impulsive Reconnection?. We present results of a quantitative analysis of structured plasma outflows above a polar coronal hole observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) spacecraft. In a 6 hr interval of continuous high-cadence SDO/AIA images, we identified more than 2300 episodes of small-scale plasma flows in the polar corona. The mean upward flow speed measured by the surfing transform technique is estimated to be 122 ± 34 km s-1, which is comparable to the local sound speed. The typical recurrence period of the flow episodes is 10-30 minutes, and the mean duration and transverse size of each episode are about 3-5 minutes and 3-4 Mm, respectively. The largest identifiable episodes last for tens of minutes and reach widths up to 40 Mm. For the first time, we demonstrate that the polar coronal-hole outflows obey a family of power-law probability distributions characteristic of impulsive interchange magnetic reconnection. Turbulent photospheric driving may play a crucial role in releasing magnetically confined plasma onto open field. The estimated occurrence rate of the detected self-similar coronal outflows is sufficient for them to make a dominant contribution to the fast-wind mass and energy fluxes and to account for the wind's small-scale structure.

Keywords: Fast solar wind, Extreme ultraviolet astronomy, Solar magnetic reconnection, Plasma jets
Characteristics of the Accelerated Electrons Moving along the Loop Derived from Cyclical Microwave Brightenings at the Footpoints. Many particles are accelerated during solar flares. To understand the acceleration and propagation processes of electrons, we require the pitch-angle distributions of the particles. The pitch angle of accelerated electrons has been estimated from the propagation velocity of a nonthermal microwave source archived in Nobeyama Radioheliograph data. We analyzed a flare event (an M-class flare on 2014 October 22) showing cyclical microwave brightenings at the two footpoint regions. Assuming that the brightenings were caused by the accelerated electrons, we approximated the velocity parallel to the magnetic field of the accelerated electrons as ~7.7 × 104 and 9.0 × 104 km s -1. The estimated pitch angle of the accelerated electrons is 69°-80° and the size of the loss cone at the footpoint (estimated from the magnetic field strength in the nonlinear force-free field model) is approximately 43°. Most of the accelerated electrons could be reflected at the footpoint region. This feature can be interpreted as brightenings produced by bouncing motion of the accelerated electrons.

Keywords: Solar radio emission, Solar flares
On the Magnetic Nature of Quiet-Sun Chromospheric Grains. Ca II K grains, i.e., intermittent, short-lived (about 1 minute), periodic (2–4 minutes), pointlike chromospheric brightenings, are considered to be the manifestations of acoustic waves propagating upward from the solar surface and developing into shocks in the chromosphere. After the simulations of Carlsson and Stein, we know that hot shocked gas moving upward interacting with the downflowing chromospheric gas (falling down after having been displaced upward by a previous shock) nicely reproduces the spectral features of the Ca II K profiles observed in such grains, i.e., a narrowband emission-like feature at the blue side of the line core. However, these simulations are one-dimensional and cannot explain the location or the pointlike shape of the grains. Here, we report on the magnetic nature of these events. Furthermore, we report on similar events occurring at the largest flux concentrations, though they are longer-lived (up to 8 minutes) and exhibit the typical signature of steep velocity gradients traveling across the atmosphere. The spectral signatures of the studied events resemble their counterparts in sunspots, the umbral flashes. We then propose that magnetohydrodynamical waves are not only channeled through the magnetic field in sunspots, but they pervade the whole atmosphere. The propagation along magnetic fields can explain the pointlike appearance of the calcium grains observed in the quiet chromosphere.

Keywords: Solar atmosphere, Spectropolarimetry, Magnetic fields, Quiet solar chromosphere
On the Magnetic Nature of Quiet-Sun Chromospheric Grains. Ca II K grains, i.e., intermittent, short-lived (about 1 minute), periodic (2-4 minutes), pointlike chromospheric brightenings, are considered to be the manifestations of acoustic waves propagating upward from the solar surface and developing into shocks in the chromosphere. After the simulations of Carlsson and Stein, we know that hot shocked gas moving upward interacting with the downflowing chromospheric gas (falling down after having been displaced upward by a previous shock) nicely reproduces the spectral features of the Ca II K profiles observed in such grains, i.e., a narrowband emission-like feature at the blue side of the line core. However, these simulations are one-dimensional and cannot explain the location or the pointlike shape of the grains. Here, we report on the magnetic nature of these events. Furthermore, we report on similar events occurring at the largest flux concentrations, though they are longer-lived (up to 8 minutes) and exhibit the typical signature of steep velocity gradients traveling across the atmosphere. The spectral signatures of the studied events resemble their counterparts in sunspots, the umbral flashes. We then propose that magnetohydrodynamical waves are not only channeled through the magnetic field in sunspots, but they pervade the whole atmosphere. The propagation along magnetic fields can explain the pointlike appearance of the calcium grains observed in the quiet chromosphere.

Keywords: Solar atmosphere, Spectropolarimetry, Magnetic fields, Quiet solar chromosphere
On the Subparsec-scale Core Composition of FR 0 Radio Galaxies. Although Fanaroff-Riley type 0 (FR 0) radio galaxies are known to be the most numerous jet population in the local Universe, they are much less explored than the well-established class of FR type I (FR I) and FR type II galaxies due to their intrinsic weakness. Observationally, their nuclear radio, optical, and X-ray properties are comparable to the nuclear environment of FR Is. The recent detection of two FR 0s in the high-energy band suggests that, like in FR Is, charged particles are accelerated there to energies that enable gamma-ray production. Up to now, only the lack of extended radio emission from FR 0s distinguishes them from FR Is. By comparing the spectral energy distribution of FR 0s with that of FR Is and in particular with that of M87 as a well-studied reference source of the FR I population, we find the broadband spectrum of FR 0 s exceptionally close to M87's quiet core emission. Relying on that similarity, we apply a lepto-hadronic jet-accretion flow model to FR 0s. This model is able to explain the broadband spectral energy distribution, with parameters close to particle-field equipartition and matching all observational constraints. In this framework, FR 0s are multimessenger jet sources, with a nature and highly magnetized environment similar to those of the naked quiet core of FR Is.

Keywords: High energy astrophysics, Gamma-ray sources, Relativistic jets, Low-luminosity active galactic nuclei, Active galactic nuclei, Fanaroff-Riley radio galaxies, Cosmic ray sources, Non-thermal radiation sources, Particle astrophysics
Is a Recently Discovered H I Cloud near M94 a Starless Dark Matter Halo?. Observations with the Five-hundred-meter Aperture Spherical Telescope have revealed the presence of a marginally resolved source of 21 cm emission from a location $\sim 50^{\prime} $ from the M94 galaxy, without a stellar counterpart down to the surface brightness limit of the DESI Imaging Legacy Survey (~29.15 mag arcsec-2 in the g band). The system (hereafter Cloud-9) has round column density isocontours and a line width consistent with thermal broadening from gas at T ~ 2 × 104 K. These properties are unlike those of previously detected dark H I clouds and similar to the expected properties of REionization-Limited-H I Clouds (RELHICs), namely, starless dark matter (DM) halos filled with gas in hydrostatic equilibrium and in thermal equilibrium with the cosmic ultraviolet background. At the distance of M94, d ~ 4.7 Mpc, we find that Cloud-9 is consistent with being a RELHIC inhabiting a Navarro-Frenk-White (NFW) DM halo of mass M 200 ~ 5 × 109 M ⊙ and concentration c NFW ~ 13. Although the agreement between the model and observations is good, Cloud-9 appears to be slightly, but systematically, more extended than expected for ΛCDM RELHICs. This may imply either that Cloud-9 is much closer than implied by its recessional velocity, v CL9 ~ 300 km s-1, or that its halo density profile is flatter than NFW, with a DM mass deficit greater than a factor of 10 at radii r ≲ 1 kpc. Further observations may aid in constraining these scenarios better and help elucidate whether Cloud-9 is the first ever observed RELHIC, a cornerstone prediction of the ΛCDM model on the smallest scales.

Keywords: Cosmology, Reionization, Dark matter