adsabs/SciX_UAT_keywords huggingface dataset:
Dynamics of Molecular Gas in the Central Region of the Quasar I Zwicky 1

We present a study of the molecular gas distribution and kinematics in the cicumnuclear region (radii ≲2 kpc) of the z ≈ 0.061 quasar I Zwicky 1 using a collection of available Atacama Large Millimeter/submillimeter Array observations of the carbon monoxide (CO) emission. With an angular resolution of ~0.″36 (corresponding to ~400 pc), the host-galaxy substructures including the nuclear molecular gas disk, spiral arms, and a compact bar-like component are resolved. We analyzed the gas kinematics based on the CO image cube and obtained the rotation curve and radial distribution of velocity dispersion. The velocity dispersion is about 30 km s-1 in the outer CO disk region and rises up to ≳100 km s-1 at radius ≲1 kpc, suggesting that the central region of the disk is dynamically hot. We constrain the CO-to-H2 conversion factor, α CO, by modeling the cold gas disk dynamics. We find that, with prior knowledge about the stellar and dark matter components, the α CO value in the circumnuclear region of this quasar host galaxy is ${1.55}_{-0.49}^{+0.47}$ ${M}_{\odot }{\left({\rm{K}}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{pc}}^{2}\right)}^{-1}$ , which is between the value reported in ultraluminous infrared galaxies and in the Milky Way. The central 1 kpc region of this quasar host galaxy has significant star formation activity, which can be identified as a nuclear starburst. We further investigate the high-velocity dispersion in the central region. We find that the interstellar medium (ISM) turbulent pressure derived from the gas velocity dispersion is in equilibrium with the weight of the ISM. This argues against extra power from active galactic nuclei feedback that significantly affects the kinematics of the cold molecular gas.

Keywords: agn host galaxies; quasars; galaxy kinematics; galaxy dynamics; molecular gas
Wavelengths and Energy Levels of the Upper Levels of Singly Ionized Nickel (Ni II) from 3d 8(3 F)5f to 3d 8(3 F)9s

Using high-resolution spectra of Ni II recorded using Fourier transform (FT) spectroscopy of continuous, nickel-helium hollow cathode discharge sources in the region 143-5555 nm (1800-70,000 cm-1, the analysis of 1016 Ni II lines confirmed and optimized 206 previously reported energy levels of the (3 F) parent term, from 3d 8(3 F)5f to 3d 8(3 F)9s, lying between 122,060 and 138,563 cm-1. The uncertainties of these levels have been improved by at least an order of magnitude compared with their previously reported values. With the increased resolution and spectral range of the FT measurements, compared to previously published grating spectra, we were able to extend our analysis to identify and establish 33 new energy levels of Ni II, which are reported here for the first time. Eigenvector compositions of all revised and newly established energy levels were calculated using the orthogonal operator method. In addition, an improved ionization energy of 146,541.35 ± 0.15 cm-1 for Ni II, using highly excited levels of the 3d 8(3 F)5g, 3d 8(3 F)6g, and 3d 8(3 F)6h configurations, has been derived.

Keywords: atomic spectroscopy; line positions; atomic data; laboratory astrophysics; spectral line identification; spectral line lists; spectroscopy
Is Extended Hard X-Ray Emission Ubiquitous in Compton-thick AGN?

The recent Chandra discovery of extended ∼kiloparsec-scale hard (>3 keV) X-ray emission in nearby Compton-thick (CT) active galactic nuclei (AGN) opens a new window to improving AGN torus modeling and investigating how the central supermassive black hole interacts with and impacts the host galaxy. Since there are only a handful of detections so far, we need to establish a statistical sample to determine the ubiquity of the extended hard X-ray emission in CT AGN and quantify the amount and extent of this component. In this paper, we present the spatial analysis results of a pilot Chandra imaging survey of seven nearby ( $0.006\lt z\lt 0.013$ ) CT AGN selected from the Swift-BAT spectroscopic AGN survey. We find that five out of the seven CT AGN show extended emission in the 3-7 keV band detected at >3σ above the Chandra point-spread function (PSF), with ∼12%-22% of the total emission in the extended components. ESO 137-G034 and NGC 3281 display biconical ionization structures with extended hard X-ray emission reaching kiloparsec scales (∼1.9 and 3.5 kpc in diameter). The other three show extended hard X-ray emission above the PSF out to at least ∼360 pc in radius. We find a trend that a minimum 3-7 keV count rate of 0.01 counts s-1 and total excess fraction >20% are required to detect a prominent extended hard X-ray component. Given that this extended hard X-ray component appears to be relatively common in this uniformly selected CT AGN sample, we further discuss the implications for torus modeling and AGN feedback.

Keywords: active galaxies; x-ray active galactic nuclei; agn host galaxies
Polarimetric Observations of PSR J0614+2229 and PSR J1938+2213 Using FAST

We presented observations of PSRs J0614+2229 and J1938+2213 using the Five-hundred-meter Aperture Spherical radio Telescope. PSR J0614+2229 shows two distinct emission states, in which the emission of state A occurs earlier than that of state B in longitude. The phase offset between the average pulse profile peaks of the two states is about 1.°05. The polarization properties of the average pulse profile of the two states are different with different linear position angle swings. We found that the emission becomes brighter during the transition between the two states, which has never been seen in other mode-changing pulsars before. PSR J1938+2213 appears to consist of a weak emission state superposed by brighter burst emissions. The weak state is always present and the energy of the strongest pulse in the burst state is about 57 times larger than that of the average pulse energy. The polarization properties of the two states are also different, and orthogonal polarization modes can be seen only in the burst state, rather than both states. Our results suggest that, for the two pulsars, the emissions of the two states may be generated in different regions in the pulsar magnetosphere.

Keywords: pulsars; radio pulsars
Lightcurves and Rotations of Trans-Neptunian Objects in the 2:1 Mean Motion Resonance with Neptune

We report the rotational lightcurves of 21 trans-Neptunian objects (TNOs) in Neptune's 2:1 mean motion resonance obtained with the 6.5 m Magellan-Baade telescope and the 4.3 m Lowell Discovery Telescope. The main survey's goal is to find objects displaying a large lightcurve amplitude that is indicative of contact binaries or highly elongated objects. In our sample, two 2:1 resonant TNOs showed a significant short-term lightcurve amplitude: 2002 VD130 and (531074) 2012 DX98. The full lightcurve of 2012 DX98 infers a periodicity of 20.80 ± 0.06 hr and amplitude of 0.56 ± 0.03 mag, whereas 2002 VD130 rotates in 9.85 ± 0.07 hr with a 0.31 ± 0.04 mag lightcurve amplitude. Based on lightcurve morphology, we classify (531074) 2012 DX98 as a likely contact binary but 2002 VD130 as a likely single elongated object. Based on our sample and the lightcurves reported in the literature, we estimate the lower percentage of nearly equal-sized contact binaries at only 7%-14% in the 2:1 resonance, which is comparable to the low fraction reported for the dynamically cold classical TNOs. This low contact binary fraction in the 2:1 Neptune resonance is consistent with the lower estimate of the recent numerical modeling. We report the Sloan g', r', and i' surface colors of 2002 VD130, which is an ultra-red TNO whereas 2012 DX98 is a very red object based on published surface colors.

Keywords: trans-neptunian objects; resonant kuiper belt objects; twotinos
No Redshift Evolution of Galaxies' Dust Temperatures Seen from 0 < z < 2

Some recent literature has claimed there to be an evolution in galaxies' dust temperatures toward warmer (or colder) spectral energy distributions (SEDs) between low and high redshift. These conclusions are driven by both theoretical models and empirical measurement. Such claims sometimes contradict one another and are prone to biases in samples or SED fitting techniques. What has made direct comparisons difficult is that there is no uniform approach to fitting galaxies' infrared/millimeter SEDs. Here we aim to standardize the measurement of galaxies' dust temperatures with a python-based SED fitting procedure, MCIRSED. 1 1 Publicly available at github.com/pdrew32/mcirsed. We draw on reference data sets observed by Infrared Astronomical Satellite, Herschel, and SCUBA-2 to test for redshift evolution out to z ~ 2. We anchor our work to the L IR-λ peak plane, where there is an empirically observed anticorrelation between IR luminosity and rest-frame peak wavelength (an observational proxy for luminosity-weighted dust temperature) such that $\left\langle {\lambda }_{\mathrm{peak}}\right\rangle ={\lambda }_{{\rm{t}}}{({L}_{\mathrm{IR}}/{L}_{{\rm{t}}})}^{\eta }$ where η = -0.09 ± 0.01, Lt = 1012 L ⊙, and λ t = 92 ± 2 μm. We find no evidence for redshift evolution of galaxies' temperatures, or λ peak, at fixed L IR from 0 < z < 2 with >99.99% confidence. Our finding does not preclude evolution in dust temperatures at fixed stellar mass, which is expected from a nonevolving L IR-λ peak relation and a strongly evolving SFR-M⋆ relation. The breadth of dust temperatures ( ${\sigma }_{\mathrm{log}{\lambda }_{\mathrm{peak}}}$ ) at a given L IR is likely driven by variation in galaxies' dust geometries and sizes, and it does not evolve. Testing for L IR-λ peak evolution toward higher redshift (z ~ 5-6) requires better sampling of galaxies' dust SEDs near their peaks (observed ~200-600 μm) with ≲1 mJy sensitivity. This poses a significant challenge to current instrumentation.

Keywords: galaxy evolution; spectral energy distribution; dust continuum emission
Effects of Solar Activity on Taylor Scale and Correlation Scale in Solar Wind Magnetic Fluctuations

The correlation scale and the Taylor scale are evaluated for interplanetary magnetic field fluctuations from two-point, single time correlation function using the Advanced Composition Explorer (ACE), Wind, and Cluster spacecraft data during the time period from 2001 to 2017, which covers over an entire solar cycle. The correlation scale and the Taylor scale are respectively compared with the sunspot number to investigate the effects of solar activity on the structure of the plasma turbulence. Our studies show that the Taylor scale increases with the increasing sunspot number, which indicates that the Taylor scale is positively correlated with the energy cascade rate, and the correlation coefficient between the sunspot number and the Taylor scale is 0.92. However, these results are not consistent with the traditional knowledge in hydrodynamic dissipation theories. One possible explanation is that in the solar wind, the fluid approximation fails at the spatial scales near the dissipation ranges. Therefore, the traditional hydrodynamic turbulence theory is incomplete for describing the physical nature of the solar wind turbulence, especially at the spatial scales near the kinetic dissipation scales.

Keywords: solar wind; interplanetary turbulence; interplanetary medium; solar magnetic fields; space plasmas; solar activity; solar cycle
Dual Effects of Ram Pressure on Star Formation in Multiphase Disk Galaxies with Strong Stellar Feedback

We investigate the impact of ram pressure stripping due to the intracluster medium (ICM) on star-forming disk galaxies with a multiphase interstellar medium maintained by strong stellar feedback. We carry out radiation-hydrodynamic simulations of an isolated disk galaxy embedded in a 1011 M⊙ dark matter halo with various ICM winds mimicking the cluster outskirts (moderate) and the central environment (strong). We find that both star formation quenching and triggering occur in ram pressure-stripped galaxies, depending on the strength of the winds. H I and H2 in the outer galactic disk are significantly stripped in the presence of moderate winds, whereas turbulent pressure provides support against ram pressure in the central region, where star formation is active. Moderate ICM winds facilitate gas collapse, increasing the total star formation rates by ∼40% when the wind is oriented face-on or by ∼80% when it is edge-on. In contrast, strong winds rapidly blow away neutral and molecular hydrogen gas from the galaxy, suppressing star formation by a factor of 2 within ∼200 Myr. Dense gas clumps with nH ≳ 10 M⊙ pc-2 are easily identified in extraplanar regions, but no significant young stellar populations are found in such clumps. In our attempts to enhance radiative cooling by adopting a colder ICM of T = 106 K, only a few additional stars are formed in the tail region, even if the amount of newly cooled gas increases by an order of magnitude.

Keywords: galaxies
Magnetic Field Dependence of Bipolar Magnetic Region Tilts on the Sun: Indication of Tilt Quenching

The tilt of the bipolar magnetic region (BMR) is crucial in the Babcock-Leighton process for the generation of the poloidal magnetic field in the Sun. Based on the thin flux-tube model of the BMR formation, the tilt is believed to be caused by the Coriolis force acting on the rising flux tube of the strong toroidal magnetic field from the base of the convection zone. We analyze the magnetic field dependence of BMR tilts using the magnetograms of the Michelson Doppler Imager (1996-2011) and Helioseismic and Magnetic Imager (2010-2018). We observe that the distribution of the maximum magnetic field (Bmax) of BMRs is bimodal. Its first peak at the low field corresponds to BMRs that do not have sunspots as counterparts in the white-light images, whereas the second peak corresponds to sunspots as recorded in both type of images. We find that the slope of Joy's law (γ0) initially increases slowly with the increase of Bmax. However, when Bmax ≳ 2 kG, γ0 decreases. Scatter of the BMR tilt around Joy's law systematically decreases with the increase of Bmax. The decrease of observed γ0 with Bmax provides a hint to a nonlinear tilt quenching in the Babcock-Leighton process. We finally discuss how our results may be used to make a connection with the thin flux-tube model.

Keywords: bipolar sunspot groups; solar cycle; solar physics; solar active region magnetic fields; solar activity; solar active regions
Recurrent Activity from Active Asteroid (248370) 2005 QN173: A Main-belt Comet

We present archival observations of main-belt asteroid (248370) 2005 QN173 (also designated 433P) that demonstrate this recently discovered active asteroid (a body with a dynamically asteroidal orbit displaying a tail or coma) has had at least one additional apparition of activity near perihelion during a prior orbit. We discovered evidence of this second activity epoch in an image captured 2016 July 22 with the DECam on the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. As of this writing, (248370) 2005 QN173 is just the eighth active asteroid demonstrated to undergo recurrent activity near perihelion. Our analyses demonstrate (248370) 2005 QN173 is likely a member of the active asteroid subset known as main-belt comets, a group of objects that orbit in the main asteroid belt that exhibit activity that is specifically driven by sublimation. We implement an activity detection technique, wedge photometry, that has the potential to detect tails in images of solar system objects and quantify their agreement with computed antisolar and antimotion vectors normally associated with observed tail directions. We present a catalog and an image gallery of archival observations. The object will soon become unobservable as it passes behind the Sun as seen from Earth, and when it again becomes visible (late 2022) it will be farther than 3 au from the Sun. Our findings suggest (248370) 2005 QN173 is most active interior to 2.7 au (0.3 au from perihelion), so we encourage the community to observe and study this special object before 2021 December.

Keywords: asteroids; main belt asteroids; comae; comets; comet tails; astronomy data analysis; comet volatiles; main-belt comets; computational methods
The Aligned Orbit of the Eccentric Warm Jupiter K2-232b

Measuring the obliquity distribution of stars hosting warm Jupiters may help us to understand the formation of close-orbiting gas giants. Few such measurements have been performed due to practical difficulties in scheduling observations of the relatively infrequent and long-duration transits of warm Jupiters. Here, we report a measurement of the Rossiter-McLaughlin effect for K2-232 b, a warm Jupiter on an 11.17 day orbit with an eccentricity of 0.26. The data were obtained with the Automated Planet Finder during two separate transits. The planet's orbit appears to be well aligned with the spin axis of the host star, with a projected spin-orbit angle of λ = -11°1 ± 6°6. Combined with the other available data, we find that high obliquities are almost exclusively associated with planets that either have an orbital separation greater than 10 stellar radii or orbit stars with effective temperatures hotter than 6000 K. This pattern suggests that the obliquities of the closest-orbiting giant planets around cooler stars have been damped by tidal effects.

Keywords: exoplanets
The Curious Case of ASASSN-20hx: A Slowly Evolving, UV- and X-Ray-Luminous, Ambiguous Nuclear Transient

We present observations of ASASSN-20hx, a nearby ambiguous nuclear transient (ANT) discovered in NGC 6297 by the All-Sky Automated Survey for Supernovae (ASAS-SN). We observed ASASSN-20hx from -30 to 275 days relative to the peak UV/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From Transiting Exoplanet Survey Satellite data, we determine that the ANT began to brighten on 2020 June 22.8 with a linear rise in flux for at least the first week. ASASSN-20hx peaked in the UV/optical 30 days later on 2020 July 22.8 (MJD = 59052.8) at a bolometric luminosity of L = (3.15 ± 0.04) × 1043 erg s-1. The subsequent decline is slower than any TDE observed to date and consistent with many other ANTs. Compared to an archival X-ray detection, the X-ray luminosity of ASASSN-20hx increased by an order of magnitude to L x ~ 1.5 × 1042 erg s-1 and then slowly declined over time. The X-ray emission is well fit by a power law with a photon index of Γ ~ 2.3-2.6. Both the optical and near-infrared spectra of ASASSN-20hx lack emission lines, unusual for any known class of nuclear transient. While ASASSN-20hx has some characteristics seen in both tidal disruption events and active galactic nuclei, it cannot be definitively classified with current data.

Keywords: accretion; active galactic nuclei; black hole physics; supermassive black holes; tidal disruption
Patterns in the Multiwavelength Behavior of Candidate Neutrino Blazars

Motivated by the identification of the blazar TXS 0506+056 as the first promising high-energy neutrino counterpart candidate, we search for additional neutrino blazar candidates among the Fermi-Large Area Telescope detected blazars. We investigate the multiwavelength behavior from radio to GeV gamma-rays of blazars found to be in spatial coincidence with single high-energy neutrinos and lower-energy neutrino flare candidates. In addition, we compare the average gamma-ray emission of the potential neutrino-emitting sources to the entire sample of gamma-ray blazars. We find that neutrino-emitting blazar candidates are statistically compatible with hypotheses of both a linear correlation and no correlation between neutrino and gamma-ray energy flux.

Keywords: high energy astrophysics; neutrino astronomy; blazars; light curves
An Enigmatic High Excitation Nebula in IC 1613 Dwarf Galaxy

We report the serendipitous discovery of a high-excitation nebula in the Local Group dwarf galaxy IC 1613. The nebula shows spectral features typical of a planetary nebula (PN), but its physical size makes it an order of magnitude larger than observed for this type of object, if indeed it belongs to IC 1613. We hypothesise that it may be an example of an over-luminous PN, a still unexplained phenomenon that deserves further investigation.

Keywords: dwarf irregular galaxies; spectroscopy
3D Numerical Simulations of Solar Quiet Chromosphere Wave Heating

Despite numerous observational and theoretical attempts, the heating problem of the solar chromosphere still remains unsolved. We develop a novel 3D two-fluid model that accounts for dynamics of charged species and neutrals, and use it to perform the numerical simulations of granulation driven jets and associated waves in a quiet region of the solar chromosphere. The energy carried by the waves is dissipated through ion-neutral collisions, which are sufficient to balance radiative energy losses and to sustain the quasi-stationary atmosphere whose ion and neutral number densities, ionization fraction, and temperature profiles are relatively close to the observationally based semi-empirical model. Additional verification of our results is provided by a good fit of the numerically predicted waveperiod variations with height to the recent observational data. These observational validations of the numerical results demonstrate that the wave heating problem of a quiet region of the chromosphere may be solved.

Keywords: quiet sun
Formation of a Long Filament Through the Connection of Two Filament Segments Observed by CHASE

We present imaging and spectroscopic diagnostics of a long filament during its formation with the observations from the Chinese Hα Solar Explorer and Solar Dynamics Observatory. The seed filament first appeared at about 05:00 UT on 2022 September 13. Afterward, it grew gradually and connected to another filament segment nearby, building up a long filament at about 20:00 UT on the same day. The CHASE Hα spectra show an obvious centroid absorption with mild broadening at the main spine of the long filament, which is interpreted as evidence of filament material accumulation. More interestingly, near the footpoints of the filament, persistent redshifts have been detected in the Hα spectra during the filament formation, indicating continuous drainage of filament materials. Furthermore, through inspecting the extreme-ultraviolet (EUV) images and magnetograms, it was found that EUV jets and brightenings appeared repeatedly at the junction of the two filament segments, where opposite magnetic polarities converged and canceled each other continuously. These results suggest the occurrence of intermittent magnetic reconnection that not only connects magnetic structures of the two filament segments but also supplies cold materials for the filament channel likely by the condensation of injected hot plasma, even though a part of the cold materials falls down to the filament footpoints at the same time.

Keywords: solar filaments; solar magnetic reconnection