Sazuna/UAT_keywords huggingface dataset:
From Nuclear to Circumgalactic: Zooming in on AGN-driven Outflows at z ∼ 2.2 with SINFONI. We use deep adaptive optics assisted integral field spectroscopy from SINFONI on the VLT to study the spatially resolved properties of ionized gas outflows driven by active galactic nuclei (AGNs) in three galaxies at z ∼ 2.2—K20-ID5, COS4-11337, and J0901 + 1814. These systems probe AGN feedback from nuclear to circumgalactic scales and provide unique insights into the different mechanisms by which AGN-driven outflows interact with their host galaxies. K20-ID5 and COS4-11337 are compact star-forming galaxies with powerful ∼1500 km s-1 AGN-driven outflows that dominate their nuclear Hα emission. The outflows do not appear to have any impact on the instantaneous star formation activity of the host galaxies, but they carry a significant amount of kinetic energy that could heat the halo gas and potentially lead to a reduction in the rate of cold gas accretion onto the galaxies. The outflow from COS4-11337 is propagating directly toward its companion galaxy COS4-11363, at a projected separation of 5.4 kpc. COS4-11363 shows signs of shock excitation and recent truncation of star formation activity, which could plausibly have been induced by the outflow from COS4-11337. J0901 + 1814 is gravitationally lensed, giving us a unique view of a compact (R = 470 ± 70 pc), relatively low-velocity (∼650 km s-1) AGN-driven outflow. J0901 + 1814 has a similar AGN luminosity to COS4-11337, suggesting that the difference in outflow properties is not related to the current AGN luminosity and may instead reflect a difference in the evolutionary stage of the outflow and/or the coupling efficiency between the AGN ionizing radiation field and the gas in the nuclear regions.

Keywords: High-redshift galaxies, Galaxy evolution, Galaxy kinematics
Intrusion of Magnetic Peninsula toward the Neighboring Opposite-polarity Region That Triggers the Largest Solar Flare in Solar Cycle 24. The largest X9.3 solar flare in solar cycle 24 and the preceding X2.2 flare occurred on 2017 September 6, in the solar active region NOAA 12673. This study aims to understand the onset mechanism of these flares via analysis of multiple observational data sets from the Hinode and Solar Dynamics Observatory and results from a nonlinear force-free field extrapolation. The most noticeable feature is the intrusion of a major negative-polarity region, appearing similar to a peninsula, oriented northwest into a neighboring opposite-polarity region. We also observe proxies of magnetic reconnection related to the intrusion of the negative peninsula: rapid changes of the magnetic field around the intruding negative peninsula; precursor brightening at the tip of the negative peninsula, including a cusp-shaped brightening that shows a transient but significant downflow (∼100 km s-1) at a leg of the cusp; a dark tube-like structure that appears to be a magnetic flux rope that erupted with the X9.3 flare; and coronal brightening along the dark tube-like structure that appears to represent the electric current generated under the flux rope. Based on these observational features, we propose that (1) the intrusion of the negative peninsula was critical in promoting the push-mode magnetic reconnection that forms and grows a twisted magnetic flux rope that erupted with the X2.2 flare, and (2) the continuing intrusion progressing even beyond the X2.2 flare is further promoted to disrupt the equilibrium that leads the reinforcement of the magnetic flux rope that erupted with the X9.3 flare.

Keywords: Solar active region magnetic fields, Solar flares, The Sun, Sunspots, Space weather, Active sun, Solar coronal mass ejections, Delta sunspots
A Small-scale Filament Eruption Inducing a Moreton Wave, an EUV Wave, and a Coronal Mass Ejection. With the launch of the Solar Dynamic Observatory, many extreme ultraviolet (EUV) waves have been observed during solar eruptions. However, joint observations of Moreton and EUV waves are still relatively rare. We present an event in active region NOAA 12740 wherein a small-scale filament eruption simultaneously results in a Moreton wave, an EUV wave, and a coronal mass ejection. First, we find that some dark elongated lanes or filamentary structures in the photosphere that exist under the small-scale filament drift downward; this manifests as the small-scale filament emerging and lifting up from the subsurface. Second, combining simultaneous observations in different EUV and Hα passbands, we study the kinematic characteristics of Moreton and EUV waves. Comparable propagation velocities and similar morphologies of the Moreton and different-passband EUV wave fronts were obtained. We deduce that Moreton and different-passband EUV waves are the perturbations in different temperature-associated layers induced by a coronal magnetohydrodynamic shock wave. We also find refracted, reflected, and diffracted phenomena during the propagation of the EUV wave. By using power-law fittings, the kinematic characteristics of unaffected, refracted, and diffracted waves were obtained. The extrapolation field derived by the potential field source surface model manifests as an interface between different magnetic systems (magnetic separatrix), resulting in the refraction, reflection, and deviation of the EUV wave.

Keywords: Solar flares, Solar coronal waves, Solar filaments, Solar activity, Solar evolution
Closure Statistics in Interferometric Data. Interferometric visibilities, reflecting the complex correlations between signals recorded at antennas in an interferometric array, carry information about the angular structure of a distant source. While unknown antenna gains in both amplitude and phase can prevent direct interpretation of these measurements, certain combinations of visibilities called closure phases and closure amplitudes are independent of antenna gains and provide a convenient set of robust observables. However, these closure quantities have subtle noise properties and are generally both linearly and statistically dependent. These complications have obstructed the proper use of closure quantities in interferometric analysis, and they have obscured the relationship between analysis with closure quantities and other analysis techniques such as self calibration. We review the statistics of closure quantities, noting common pitfalls that arise when approaching low signal to noise due to the nonlinear propagation of statistical errors. We then develop a strategy for isolating and fitting to the independent degrees of freedom captured by the closure quantities through explicit construction of linearly independent sets of quantities along with their noise covariance in the Gaussian limit, valid for moderate signal to noise, and we demonstrate that model fits have biased posteriors when this covariance is ignored. Finally, we introduce a unified procedure for fitting to both closure information and partially calibrated visibilities, and we demonstrate both analytically and numerically the direct equivalence of inference based on closure quantities to that based on self calibration of complex visibilities with unconstrained antenna gains.

Keywords: Aperture synthesis, Astrostatistics techniques, Very long baseline interferometry, Interferometry, Radio interferometers, Astrostatistics strategies
Spectroscopic Constraints on the Buildup of Intracluster Light in the Coma Cluster. The stellar content of the intracluster light (ICL) provides unique insight into the hierarchical assembly process of galaxy clusters. We present optical spectra of three ICL regions (μg ≈ 25.3-26.2 mag arcsec-2) in the Coma cluster, located between 100 and 180 kpc from their nearest brightest cluster galaxies (BCGs): NGC 4889 and NGC 4874. Integral-field unit (IFU) spectroscopy with 13.5 hr on-source integration was acquired in an ancillary program within the Sloan Digital Sky Survey-IV MaNGA survey. We stacked the 127 individual fiber spectra in each IFU to achieve a 1σ limiting surface brightness of 27.9 mag arcsec-2, corresponding to a mean signal-to-noise ratio in the optical of 21.7, 9.0, and 11.7 Å-1, for each ICL region. We apply stellar population models to the stacked spectra. Our results show that the velocity dispersions of ICL regions are very high (σ ∼ 630 km s-1), indicating the stars in these regions are tracing the gravitational potential of the cluster, instead of any individual galaxy. The line-of-sight velocities are different from each other by ∼700 km s-1, while the velocity of each region is similar to the closest BCG. This suggests that the ICL regions are associated with two distinct subclusters centered on NGC 4889 and NGC 4874. The stellar populations of these regions are old and metal-poor, with ages of ${12.7}_{-3.4}^{+1.0}$ , ${6.7}_{-2.0}^{+2.9}$ , and ${9.7}_{-3.5}^{+3.5}$ Gyr, and [Fe/H] of $-{1.0}_{-0.3}^{+0.2}$ , $-{0.6}_{-0.5}^{+0.3}$ , and $-{0.8}_{-0.4}^{+0.3}$ . From the derived age and metallicity, the buildup of ICL in Coma is likely to be through the accretion of low-mass galaxies or the tidal stripping of the outskirts of massive galaxies that have ended their star formation early on, instead of directly from major mergers of massive galaxies.

Keywords: Galaxy evolution, Coma Cluster
What Makes Lyα Nebulae Glow? Mapping the Polarization of LABd05. "Lyα nebulae" are giant (∼100 kpc), glowing gas clouds in the distant universe. The origin of their extended Lyα emission remains a mystery. Some models posit that Lyα emission is produced when the cloud is photoionized by UV emission from embedded or nearby sources, while others suggest that the Lyα photons originate from an embedded galaxy or active galactic nucleus (AGN) and are then resonantly scattered by the cloud. At least in the latter scenario, the observed Lyα emission will be polarized. To test these possibilities, we are conducting imaging polarimetric observations of seven Lyα nebulae. Here we present our results for LABd05, a cloud at z = 2.656 with an obscured, embedded AGN to the northeast of the peak of Lyα emission. We detect significant polarization. The highest polarization fractions P are ∼10%-20% at ∼20-40 kpc southeast of the Lyα peak, away from the AGN. The lowest P, including upper limits, are ∼5% and lie between the Lyα peak and AGN. In other words, the polarization map is lopsided, with P increasing from the Lyα peak to the southeast. The measured polarization angles θ are oriented northeast, roughly perpendicular to the P gradient. This unique polarization pattern suggests that (1) the spatially offset AGN is photoionizing nearby gas and (2) escaping Lyα photons are scattered by the nebula at larger radii and into our sightline, producing tangentially oriented, radially increasing polarization away from the photoionized region. Finally we conclude that the interplay between the gas density and ionization profiles produces the observed central peak in the Lyα emission. This also implies that the structure of LABd05 is more complex than assumed by current theoretical spherical or cylindrical models.

Keywords: Galaxy clusters, Intergalactic medium
The Metallicity Gradient and Complex Formation History of the Outermost Halo of the Milky Way. We present an examination of the metallicity distribution function of the outermost stellar halo of the Galaxy based on an analysis of both local (within 4 kpc of the Sun, ∼16,500 stars) and non-local (∼21,700 stars) samples. These samples were compiled using spectroscopic metallicities from the Sloan Digital Sky Survey and photometric metallicities from the SkyMapper Southern Survey. We detect a negative metallicity gradient in the outermost halo (r &gt; 35 kpc from the Galactic center), and find that the frequency of very metal-poor ([Fe/H] &lt; -2.0) stars in the outer-halo region reaches up to ∼60% in our most distant sample, commensurate with previous theoretical predictions. This result provides clear evidence that the outer-halo formed hierarchically. The retrograde stars in the outermost halo exhibit a roughly constant metallicity, which may be linked to the accretion of the Sequoia progenitor. In contrast, prograde stars in the outermost halo exhibit a strong metallicity-distance dependence, indicating that they likely originated from the accretion of galaxies less massive than the Sequoia progenitor galaxy.

Keywords: Milky Way formation, Stellar populations, Stellar kinematics, Galaxy structure, Milky Way dynamics, Milky Way stellar halo, Population II stars, Milky Way evolution, Metallicity, Milky Way Galaxy
Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?. Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP effect (I-FIP). Here we observe patches of I-FIP effect solar plasma in AR 12673, a highly complex βγδ active region. We argue that the umbrae of coalescing sunspots, and more specifically strong light bridges within the umbrae, are preferential locations for observing I-FIP effect plasma. Furthermore, the magnetic complexity of the active region and major episodes of fast flux emergence also lead to repetitive and intense flares. The induced evaporation of the chromospheric plasma in flare ribbons crossing umbrae enables the observation of four localized patches of I-FIP effect plasma in the corona of AR 12673. These observations can be interpreted in the context of the ponderomotive force fractionation model which predicts that plasma with I-FIP effect composition is created by the refraction of waves coming from below the chromosphere. We propose that the waves generating the I-FIP effect plasma in solar active regions are generated by subphotospheric reconnection of coalescing flux systems. Although we only glimpse signatures of I-FIP effect fractionation produced by this interaction in patches on the Sun, on highly active M stars it may be the dominant process.

Keywords: Solar flares, The Sun, Sunspots, Solar abundances, Solar magnetic fields
Propulsion of Spacecraft to Relativistic Speeds Using Natural Astrophysical Sources. In this paper, we explore from a conceptual standpoint the possibility of using natural astrophysical sources to accelerate spacecraft to relativistic speeds. We focus on light sails and electric sails, which are reliant on momentum transfer from photons and protons, respectively, because these two classes of spacecraft are not required to carry fuel on board. The payload is assumed to be stationed near the astrophysical source, and the sail is subsequently unfolded and activated when the source is functional. By considering a number of astrophysical objects such as massive stars, microquasars, supernovae, pulsar wind nebulae, and active galactic nuclei, we show that terminal speeds approaching the speed of light might be realizable under idealized circumstances provided that sufficiently advanced sail materials and control techniques exist. We also investigate the constraints arising from the sail's material properties, the voyage through the ambient source environment, and the passage through the interstellar medium. While all of these considerations pose significant challenges to spacecraft, our analysis indicates that they are not insurmountable in optimal conditions. Finally, we sketch the implications for carrying out future technosignature searches.

Keywords: Space vehicle instruments, High energy astrophysics, Technosignatures, Astrobiology, Interstellar medium, Search for extraterrestrial intelligence
Detection of Vibrational Emissions from the Helium Hydride Ion (HeH<SUP>+</SUP>) in the Planetary Nebula NGC 7027. We report the detection of emission in the V = 1 - 0 P(1) (3.51629 μm) and P(2) (3.60776 μm) rovibrational lines of the helium hydride cation (HeH+) from the planetary nebula NGC 7027. These detections were obtained with the iSHELL spectrograph on NASA's Infrared Telescope Facility on Maunakea. They confirm the discovery of HeH+ reported recently by Güsten et al., who used the GREAT instrument on the SOFIA airborne observatory to observe its pure rotational J = 1 - 0 transition at 149.137 μm. The flux measured for the HeH+ V = 1 - 0 P(1) line is in good agreement with our model for the formation, destruction, and excitation of HeH+ in NGC 7027. The measured strength of the J = 1 - 0 pure rotational line, however, exceeds the model prediction significantly, as does that of the V = 1 - 0 P(2) line, by factors of 2.9 and 2.3 respectively. Possible causes of these discrepancies are discussed. Our observations of NGC 7027, covering the 3.26-3.93 μm spectral region, have led to the detection of more than 60 spectral lines including nine rovibrational emissions from CH+. The latter are detected for the first time in an astronomical source.

Keywords: Interstellar molecules, Astrochemistry, Infrared astronomy, Molecular physics, Planetary nebulae, Interstellar emissions, Interstellar medium
Wide-band Rotation Measure Synthesis. Rotation measure synthesis allows the estimation of Faraday dispersion via a Fourier transform and is the primary tool to probe cosmic magnetic fields. We show this can be considered mathematically equivalent to the one-dimensional (1D) interferometric intensity measurement equation, albeit in a different Fourier space. As a result, familiar concepts in 2D intensity interferometry designed to correctly account for a range of instrumental conditions can be translated to the analysis of Faraday dispersion. In particular, we show how to model the effect of channel averaging during Faraday reconstruction, which has to date limited the progress of polarimetric science using wide-band measurements. Further, we simulate 1D sparse reconstruction with channel averaging for realistic frequency coverages, and show that it is possible to recover signals with large rotation measure values that were previously excluded from possible detection. This is especially important for low-frequency and wide-band polarimetry. We extended these ideas to introduce mosaicking in Faraday depth into the channel-averaging process. This work thus provides the first framework for correctly undertaking wide-band rotation measure synthesis, including the provision to add data from multiple telescopes, a prospect that should vastly improve the quality and quantity of polarimetric science. This is of particular importance for extreme environments that generate high magnetic fields such as those associated with pulsars and fast radio bursts, and will allow such sources to be accurately used as probes of cosmological fields.

Keywords: Radio interferometry, Spectropolarimetry, Polarimetry
Thirty Years of Radio Observations of Type Ia SN 1972E and SN 1895B: Constraints on Circumstellar Shells. We have imaged 35 yr of archival Very Large Array observations of the nearby (dL = 3.15 Mpc) Type Ia supernovae SN 1972E and SN 1895B between 9 and 121 yr post-explosion. No radio emission is detected, constraining their radio luminosities to be Lν,8.5GHz &lt; 6.0 × 1023 erg s-1 Hz-1 45 yr post-explosion and Lν,8.5GHz &lt; 8.9 × 1023 erg s-1 Hz-1 121 yr post-explosion, respectively. These limits imply a clean circumstellar medium (CSM), with n &lt; 0.9 cm-3 out to radii of a few ×1018 cm, if the SN blast wave is expanding into uniform density material. We also constrain the presence of CSM shells surrounding the progenitor of SN 1972E. We rule out essentially all medium and thick shells with masses of 0.05-0.3 M⊙ at radii between ∼1017 and 1018 cm, and thin shells at specific radii with masses down to ≲0.01 M⊙. These constraints rule out swaths of parameter space single and double degenerate progenitor scenarios, including recurrent nova, core-degenerate objects, ultra-prompt explosions, and white dwarf (WD) mergers with delays of a few hundred years between the onset of merger and explosion. Allowed progenitors include WD-WD systems with a significant (&gt;104 yr) delay from the last episode of common envelope evolution and single degenerate systems undergoing recurrent nova—provided that the system has been in the nova phase for ≳104 yr, such that a large (&gt;1018 cm) cavity has been evacuated. Future multi-epoch observations of additional intermediate-aged SNe Ia will provide a comprehensive view of the large-scale CSM around these explosions.

Keywords: Radio continuum emission, Circumstellar matter, Type Ia supernovae, Supernovae
Constraints on the Velocity Dispersion of Dark Matter from Cosmology and New Bounds on Scattering from the Cosmic Dawn. The observational value of the velocity dispersion, ${\rm{\Delta }}\upsilon $ , is missing in the dark matter (DM) puzzle. Nonzero or nonthermal DM velocities can drastically influence large-scale structure and the 21 cm temperature at the epoch of the cosmic dawn, as well as the estimation of DM physical parameters, such as mass and interaction couplings. To study the phenomenology of ${\rm{\Delta }}\upsilon $ , we model the evolution of DM in terms of a simplistic and generic Boltzmann-like momentum distribution. Using cosmological data from the cosmic microwave background, baryonic acoustic oscillations, and red luminous galaxies, we constrain the DM velocity dispersion for a broad range of masses, ${10}^{-3}\,\mathrm{eV}\lt {{\rm{m}}}_{\chi }\lt {10}^{9}\,\mathrm{eV}$ , finding ${\rm{\Delta }}{\upsilon }_{0}\lesssim 0.33\mathrm{km}\ {{\rm{s}}}^{-1}$ (99% CL). Including the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) T21 measurements, we extend our study to constrain the baryon-DM interaction in the range of DM velocities allowed by our analysis. As a consequence, we present new bounds on two electromagnetic models of DM, namely minicharged particles (MCPs) and the electric dipole moment (EDM). For MCPs, the parameter region that is consistent with EDGES and independent bounds on cosmological and stellar physics is very small, pointing to the subelectronvolt mass regime of DM. A window in the MeV-GeV may still be compatible with these bounds for MCP models without a hidden photon. But the EDM parameter region consistent with EDGES is excluded by Big Bang nucleosynthesis and collider physics.

Keywords: Cosmology, Warm dark matter, Large-scale structure of the universe, Cold dark matter, Cosmological neutrinos, Dark matter detectors, Reionization, Solar particle emission, Dark matter, Particle astrophysics, Hot dark matter
Constraints on Nonlinear Tides due to p-g Mode Coupling from the Neutron Star Merger GW170817. It has been suggested by Weinberg et al. that an instability due to the nonlinear coupling of a neutron star's tide to its p- and g-modes could affect the gravitational-wave phase evolution of a neutron star binary. Weinberg suggests that this instability can turn on as the gravitational waves pass through the sensitive band of ground-based detectors, although the size of the effect is not known. The discovery of the binary neutron star merger GW170817 provides an opportunity to look for evidence of nonlinear tides from p-g mode coupling. We compute Bayesian evidences that compare waveform models that include the p-g mode coupling with models that do not. We find that the consistency between GW170817 signal and the p-g mode model reported by Abbott et al. is due to a degeneracy between the phenomenological waveform used to model the effect of nonlinear tides and the standard post-Newtonian waveform. We investigate the consistency of the GW170817 signal with regions of the parameter space where the effect of nonlinear tides is not degenerate with the standard model. Regions of the nonlinear tide parameter space that have a fitting factor of less than 99% (98.5%) are disfavored by a Bayes factor of 15 (25). We conclude that regions of the parameter space where nonlinear tides produce a measurable effect are strongly disfavored and improved theoretical modeling will be needed if future observations are to constrain nonlinear tides from p-g mode coupling in neutron stars.

Keywords: Neutron stars, Compact binary stars, Gravitational waves, Close binary stars