adsabs/SciX_UAT_keywords huggingface dataset:
Neutrino Rocket Jet Model: An Explanation of High-velocity Pulsars and Their Spin-down Evolution

The fact that the spatial velocity of pulsars is generally higher than that of their progenitor stars has bothered astronomers for nearly 50 years. It has been extensively argued that the high pulsar velocity should be acquired during a natal kick process on a timescale of 100 ms-10 s in the supernova explosion, in which some asymmetrical dynamical mechanism plays a key role. However, a satisfactory picture generally is still lacking. In this study, it is argued that the neutrino rocket model can well account for the high speed as well as the long-term evolution behaviors of pulsars. The neutrinos are emitted from superfluid vortex neutrons through the neutrino cyclotron radiation mechanism. The unique characters of left-handed neutrinos and right-handed antineutrinos resulting from the nonconservation of parity in weak interactions play a major role in the spatial asymmetry. The continuous acceleration of pulsars can be naturally explained by this model, which yields a maximum velocity surpassing 1000 km s-1. The alignment between the spinning axis and the direction of motion observed for the Crab pulsar (PSR 0531) and the Vela pulsar (PSR 0833) can be well accounted for. The observed correlation between the spin-down rate and the period of long-period pulsars with P ≳ 0.5 s can also be satisfactorily explained.

Keywords: neutron stars; pulsars; proper motions; stellar evolutionary models
Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVII. Black Hole Mass Distribution at z 6 Estimated via Spectral Comparison with Low-z Quasars

We report the distribution of black hole (BH) masses and Eddingont ratios estimated for a sample of 131 low luminosity quasars in the early cosmic epoch (5.6 < z < 7.0). Our work is based on the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which has constructed a low luminosity quasar sample down to M 1450 ~ - 21 mag, exploiting the survey data of Hyper Suprime-Cam installed on Subaru Telescope. The discovery spectra of these quasars are limited to the rest-frame wavelengths of ~1200-1400 Å, which contain no emission lines that can be used as BH mass estimators. In order to overcome this problem, we made use of low-z counterpart spectra from the Sloan Digital Sky Survey, which are spectrally matched to the high-z spectra in overlapping wavelengths. We then combined the C IV emission line widths of the counterparts with the continuum luminosity from the SHELLQs data to estimate BH masses. The resulting BH mass distribution has a range of ~107-10 M ⊙, with most of the quasars having BH masses ~108 M ⊙ with sub-Eddington accretion. The present study provides not only a new insight into normal quasars in the reionization epoch, but also a new promising way to estimate BH masses of high-z quasars without near-infrared spectroscopy.

Keywords: quasars; supermassive black holes; reionization
CHORUS. III. Photometric and Spectroscopic Properties of Lyα Blobs at z = 4.9-7.0

We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Lyα blobs (LABs), dubbed z70-1 and z49-1 at z = 6.965 and z = 4.888, respectively, that are Lyα emitters with a bright (log{L}Lyα/[erg s-1]> 43.4) and spatially extended Lyα emission, and present the photometric and spectroscopic properties of a total of seven LABs: the two new LABs and five previously known LABs at z = 5.7-6.6. The z70-1 LAB shows extended Lyα emission with a scale length of 1.4 ± 0.2 kpc, about three times larger than the UV continuum emission, making z70-1 the most distant LAB identified to date. All of the seven LABs, except z49-1, exhibit no active galactic nucleus (AGN) signatures such as X-ray emission, N V λ1240 emission, or Lyα line broadening, while z49-1 has a strong C IV λ1548 emission line indicating an AGN on the basis of the UV-line ratio diagnostics. We carefully model the point-spread functions of the HSC images and conduct two-component exponential profile fitting to the extended Lyα emission of the LABs. The Lyα scale lengths of the core (star-forming region) and halo components are rc = 0.6-1.2 kpc and rh = 2.0-13.8 kpc, respectively. The relations between the scale lengths and galaxy properties (Lyα luminosity LLyα, Lyα rest-frame equivalent width EW0, and UV continuum magnitude MUV) of our LABs are similar to those of Lyα halos (LAHs) identified around star-forming galaxies found previously by the Very Large Telescope/MUSE at similar redshifts, suggesting that our LABs are likely the bright version of high-z LAHs.

Keywords: galaxy formation; galaxy evolution; high-redshift galaxies; observational cosmology
Switchback Boundary Dissipation and Relative Age

We examine Parker Solar Probe (PSP) magnetic field and plasma observations during its first encounter with the Sun in early 2018 November. During this perihelion time, impulsive reversals in the magnetic field, called "switchbacks," were found in the data set characterized by a quick rotation in B along with a simultaneous increase in solar wind flow. In this work, we examine the structure and morphology of 920 switchback boundaries as PSP enters and exits the structures, specifically looking for evidence of boundary degradation, dissipation, and associated ultralow frequency (ULF) magnetic wave activity. We find that boundaries with the most abrupt, step-function-like change in Br and Vr also show little evidence of dissipation and ULF wave activity. In contrast, there is a set of boundaries that appears highly degraded with ULF magnetic activity in the vicinity of the boundary. We thus infer that the steep, step-like boundaries with little ULF activity are relatively young in comparison to the degraded boundaries. The distribution in relative ages suggests that the switchback boundary formation process is dynamic and evolving, even occurring near the PSP observation point inside of 40 Rs.

Keywords: solar wind; solar physics; solar magnetic flux emergence; solar magnetic fields
Large-format X-Ray Reflection Grating Operated in an Echelle-like Mounting

We report on resolving power measurements of an X-ray reflection grating designed for use in an astronomical soft X-ray spectrograph. The grating was patterned via electron-beam lithography (EBL) to have fanned grooves to match the convergence of an illuminating beam. Grating measurements were conducted in an echelle-like mounting, which yields access to high diffraction orders in the soft X-ray bandpass (0.2-2.0 keV). By comparing the zeroth-order line-spread function to the telescope focus, we find evidence for minimal broadening (<1″) introduced by the figure of the grating. In addition, we fit for the spectral resolution (R = λ/Δλ) intrinsic to this grating using a Bayesian Markov Chain Monte Carlo approach. Using an ensemble fitting technique, we find that the grating resolution R exceeds 2200 (3σ lower bound). This current grating resolution meets the performance required for a notional soft X-ray grating spectroscopy mission measuring hot baryonic material in the extended halos of galaxies. Using ray-trace simulations, we identify a geometric aberration resulting from path length differences across the width of the grating as a limiting factor in assessing the resolution of these gratings and discuss methods for placing better constraints on the inherent resolution of X-ray astronomical reflection gratings fabricated using EBL.

Keywords: astronomical instrumentation; bayesian statistics; astronomical techniques; spectroscopy
Mergers of Supermassive and Intermediate-mass Black Holes in Galactic Nuclei from Disruptions of Star Clusters

Gravitational waves (GWs) offer an unprecedented opportunity to survey the sky and detect mergers of compact objects. While intermediate-mass black holes (IMBHs) have not been detected beyond any reasonable doubt with either dynamical or accretion signatures, the GW landscape appears very promising. Mergers of an IMBH with a supermassive black hole (SMBH) will be primary sources for the planned space-based mission LISA and could be observed up to the distant universe. SMBH-IMBH binaries can be formed as a result of the migration and merger of stellar clusters at the center of galaxies, where an SMBH lurks. We build for the first time a semianalytical framework to model this scenario and find that the comoving merger rate of SMBH-IMBH binaries is ~10-4 Gpc-3 yr-1 in the local universe for a unity IMBH occupation fraction, scales linearly with it, and has a peak at z ≈ 0.5-2. Our model predicts ~0.1 events yr-1 within redshift z ≈ 3.5 if 10% of the inspiraled star clusters hosted an IMBH, while ~1 event yr-1 for a unity occupation fraction. More than 90% of these systems will be detectable with LISA with a signal-to-noise ratio larger than 10, promising to potentially find a family of IMBHs.

Keywords: astrophysical black holes; supermassive black holes; intermediate-mass black holes; gravitational waves; globular star clusters
The Proper Motion of the Pulsar J1124-5916 in the Galactic Supernova Remnant G292.0+1.8

We present the first direct measurement of the proper motion of pulsar J1124-5916 in the young, oxygen-rich supernova remnant G292.0+1.8. Using deep Chandra ACIS-I observations from 2006 to 2016, we measure a positional change of 0.″21 ± 0.″05 over the ~10 yr baseline, or ~0.″02 yr-1. At a distance of 6.2 ± 0.9 kpc, this corresponds to a kick velocity in the plane of the sky of 612 ± 152 km s-1. We compare this direct measurement against the velocity inferred from estimates based on the center of mass of the ejecta. Additionally, we use this new proper-motion measurement to compare the motion of the neutron star to the center of expansion of the optically emitting ejecta. We derive an age estimate for the supernova remnant of ≳2000 yr. The high measured kick velocity is in line with recent studies of high proper motion neutron stars in other Galactic supernova remnants and consistent with a hydrodynamic origin to the neutron star kick.

Keywords: pulsars; stellar kinematics
Structural Evolution in Massive Galaxies at z ∼ 2

We present 0"2 resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations at 870 μm in a stellar mass-selected sample of 85 massive ( ${M}_{\star }\gt {10}^{11}\,{M}_{\odot }$ ) star-forming galaxies (SFGs) at $z=1.9\mbox{--}2.6$ in the CANDELS/3D-Hubble Space Telescope fields of UDS and GOODS-S. We measure the effective radius of the rest-frame far-infrared (FIR) emission for 62 massive SFGs. They are distributed over wide ranges of FIR size from ${R}_{{\rm{e}},\mathrm{FIR}}=0.4\,\mathrm{kpc}$ to ${R}_{{\rm{e}},\mathrm{FIR}}=6\,\mathrm{kpc}$ . The effective radius of the FIR emission is smaller by a factor of ${2.3}_{-1.0}^{+1.9}$ than the effective radius of the optical emission and is smaller by a factor of ${1.9}_{-1.0}^{+1.9}$ than the half-mass radius. Taking into account potential extended components, the FIR size would change only by ∼10%. By combining the spatial distributions of the FIR and optical emission, we investigate how galaxies change the effective radius of the optical emission and the stellar mass within a radius of 1 kpc, ${M}_{1\mathrm{kpc}}$ . The compact starburst puts most of the massive SFGs on the mass-size relation for quiescent galaxies (QGs) at z ∼ 2 within 300 Myr if the current star formation activity and its spatial distribution are maintained. We also find that within 300 Myr, ∼38% of massive SFGs can reach the central mass of ${M}_{1\mathrm{kpc}}={10}^{10.5}\,{M}_{\odot }$ , which is around the boundary between massive SFGs and QGs. These results suggest an outside-in transformation scenario in which a dense core is formed at the center of a more extended disk, likely via dissipative in-disk inflows. Synchronized observations at ALMA 870 μm and James Webb Space Telescope 3-4 μm will explicitly verify this scenario.

Keywords: high-redshift galaxies; starburst galaxies; interstellar medium; galaxy structure; galaxy bulges
Rotationally Resolved Mid-infrared Spectroscopy of (16) Psyche

Asteroid (16) Psyche is theorized to be an exposed iron core of a primordial asteroid and is the target of the upcoming NASA Psyche mission. Recent observations of Psyche identified the presence of rotational heterogeneity, a fine-grained regolith, pyroxene, and hydrated minerals on its surface. We obtained rotationally resolved mid-infrared (MIR) spectroscopy of Psyche with the Stratospheric Observatory for Infrared Astronomy to explore its compositional heterogeneity and to assess its mineralogy. We used a thermophysical model of Psyche to estimate and remove its thermal flux at the time of observation to obtain emissivity spectra at 14 different epochs in its rotation. We find that the MIR emissivity does not vary significantly over the rotation of the asteroid, though this may be due to similar aspect angles. We find a lack of mineralogical features, which could suggest that materials on Psyche in the region we observed are not infrared active and consistent with a metal or oxide surface. Differences between the presented spectra and previous studies might indicate a hemispherical compositional dichotomy.

Keywords: main belt asteroids; asteroid surfaces; infrared spectroscopy; observational astronomy
Two Remarkably Luminous Galaxy Candidates at z ≈ 10-12 Revealed by JWST

The first few 100 Myr at z > 10 mark the last major uncharted epoch in the history of the universe, where only a single galaxy (GN-z11 at z ≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z > 10 galaxies with JWST/NIRCam photometry spanning ≈1-5 μm and covering 49 arcmin2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two M UV ≈ -21 systems: GLASS-z12 and GLASS-z10. These galaxies display abrupt ≳1.8 mag breaks in their spectral energy distributions (SEDs), consistent with complete absorption of flux bluewards of Lyα that is redshifted to $z={12.4}_{-0.3}^{+0.1}$ and $z={10.4}_{-0.5}^{+0.4}$ . Lower redshift interlopers such as quiescent galaxies with strong Balmer breaks would be comfortably detected at >5σ in multiple bands where instead we find no flux. From SED modeling we infer that these galaxies have already built up ~109 solar masses in stars over the ≲300-400 Myr after the Big Bang. The brightness of these sources enable morphological constraints. Tantalizingly, GLASS-z10 shows a clearly extended exponential light profile, potentially consistent with a disk galaxy of r 50 ≈ 0.7 kpc. These sources, if confirmed, join GN-z11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area >10× larger than we have studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn epoch, with implications for just how early these galaxies began forming. This, in turn, suggests that future deep JWST observations may identify relatively bright galaxies to much earlier epochs than might have been anticipated.

Keywords: james webb space telescope; galaxy evolution; early universe; high-redshift galaxies; galaxy formation
Physical Evolution of Dark Matter Halo around the Depletion Boundary

We investigate the buildup of the halo profile out to large scale in a cosmological simulation, focusing on the roles played by the recently proposed depletion radii. We explicitly show that halo growth is accompanied by the depletion of the environment, with the inner depletion radius demarcating the two. This evolution process is also observed via the formation of a trough in the bias profile, with the two depletion radii identifying key scales in the evolution. The ratio between the inner depletion radius and the virial radius is approximately a constant factor of 2 across redshifts and halo masses. The ratio between their enclosed densities is also close to a constant of 0.18. These simple scaling relations reflect the largely universal scaled mass profile on these scales, which only evolves weakly with redshift. The overall picture of the boundary evolution can be broadly divided into three stages according to the maturity of the depletion process, with cluster halos lagging behind low-mass ones in the evolution. We also show that the traditional slow and fast accretion dichotomy of halo growth can be identified as accelerated and decelerated depletion phases, respectively.

Keywords: dark matter; galaxy dark matter halos; large-scale structure of the universe; n-body simulations
Constraining Circumgalactic Turbulence with QSO Absorption Line Measurements

Our knowledge of the circumgalactic medium (CGM) is mostly based on quasar absorption line measurements. These have uncovered a multiphase medium that is likely highly turbulent, but constraints of this turbulence are limited to measurements of the nonthermal width of absorption line components (b turb) and the line-of-sight velocity dispersion between components (σ LOS). Here we analyze a suite of CGM simulations to determine how well these indirect measures are related to the underlying CGM. Our simulations track the nonequilibrium evolution of all commonly observed ions and consist of two main types: small-scale simulations of regions of homogenous CGM turbulence and global simulations of inhomogenous turbulence throughout a galactic halo. From each simulation, we generate mock spectra of Si II, Si IV, C IV, and O VI, which allow us to directly compare b turb and σ LOS to the true line-of-sight turbulence (σ 1D). In the small-scale simulations, b turb is only weakly correlated with σ 1D, likely because it measures random motions within individual warm CGM clouds, which do not sample the overall random motions. Meanwhile, σ LOS and σ 1D are strongly correlated with σ 1D ≈ σ LOS + 10 km s-1 in the densest regions we simulated, although the strength of this correlation depended weakly on the gas phase being probed. Our large-scale simulations also indicate that b turb and σ 1D are largely uncorrelated and that σ 1D ≈ σ LOS + 10 km s-1 on average, although it varies along individual sight lines. Moreover, the σ LOS distributions from our global simulations are similar to recent observations, suggesting that this quantity may provide useful constraints on circumgalactic turbulence regardless of the axis probed.

Keywords: circumgalactic medium; astrochemistry; hydrodynamical simulations; magnetohydrodynamical simulations; galaxy kinematics
Two Flares with One Shock: The Interesting Case of 3C 454.3

The quasar 3C 454.3 is a blazar known for its rapid and violent outbursts seen across the electromagnetic spectrum. Using γ-ray, X-ray, multiband optical, and very-long-baseline interferometric data we investigate the nature of two such events that occurred in 2013 and 2014 accompanied by strong variations in optical polarization, including a ∼230° electric vector position angle (EVPA) rotation. Our results suggest that a single disturbance was responsible for both flaring events. We interpret the disturbance as a shock propagating down the jet. Under this interpretation the 2013 flare originated most likely due to changes in the viewing angle caused by perhaps a bent or helical trajectory of the shock upstream of the radio core. The 2014 flare and optical polarization behavior are the result of the shock exiting the 43 GHz radio core, suggesting that shock crossings are one of the possible mechanisms for EVPA rotations.

Keywords: relativistic jets; blazars; supermassive black holes; radio loud quasars
Can the Gravitational Effect of Planet X be Detected in Current-era Tracking of the Known Major and Minor Planets?

Using Fisher information matrices, we forecast the uncertainties σ M on the measurement of a "Planet X" at heliocentric distance d X via its tidal gravitational field's action on the known planets. Using planetary measurements currently in hand, including ranging from the Juno, Cassini, and Mars-orbiting spacecraft, we forecast a median uncertainty (over all sky positions) of ${\sigma }_{M}=0.22\,{M}_{\oplus }{({d}_{x}/400{\rm{au}})}^{3}.$ A 5σ detection of a 5 M ⊕ Planet X at d X = 400 au should be possible over the full sky but over only 5% of the sky at d X = 800 au. The gravity of an undiscovered Earth- or Mars-mass object should be detectable over 90% of the sky to a distance of 260 or 120 au, respectively. Upcoming Mars ranging improves these limits only slightly. We also investigate the power of high-precision astrometry of ≈8000 Jovian Trojans over the 2023-2035 period from the upcoming Legacy Survey of Space and Time (LSST). We find that the dominant systematic errors in optical Trojan astrometry (photocenter motion, nongravitational forces, and differential chromatic refraction) can be solved internally with minimal loss of information. The Trojan data allow cross-checks with Juno/Cassini/Mars ranging, but do not significantly improve the best achievable σ M values until they are ≳10× more accurate than expected from LSST. The ultimate limiting factor in searches for a Planet X tidal field is confusion with the tidal field created by the fluctuating quadrupole moment of the Kuiper Belt as its members orbit. This background will not, however, become the dominant source of uncertainty until the data get substantially better than they are today.

Keywords: planetary dynamics; fisher's information; kuiper belt; trans-neptunian objects; astrometry; gravitation
Surprisingly Strong K-band Emission Found in Low-luminosity Active Galactic Nuclei

We examine the near-infrared (NIR) emission from low-luminosity active galactic nuclei (LLAGNs). Our galaxy sample includes 15 objects with detected 2-10 keV X-ray emission, dynamical black hole mass estimates from the literature, and available Gemini/NIFS integral field spectroscopy data. We find evidence for red continuum components at the center of most galaxies, consistent with the hot dust emission seen in higher-luminosity AGNs. We decompose the spectral data cubes into a stellar and continuum component, assuming the continuum component comes from thermal emission from hot dust. We detect nuclear thermal emission in 14 out of 15 objects. This emission causes weaker CO absorption lines and redder continuum (2.05-2.28 μm) in our K-band data, as expected from hot dust around an AGN. The NIR emission is clearly correlated with the 2-10 keV X-ray flux, with a Spearman coefficient of r spearman = 0.69 suggesting a >99% significance of correlation, providing further evidence of an AGN origin. Our sample has typical X-ray and NIR fluxes 3-4 orders of magnitude less luminous than previous work studying the NIR emission from AGNs. We find that the ratio of NIR to X-ray emission increases toward lower Eddington ratios. The NIR emission in our sample is often brighter than the X-ray emission, with our K-band AGN luminosities comparable to or greater than the 2-10 keV X-ray luminosities in all objects with Eddington ratios below 0.01%. The nature of this LLAGN NIR emission remains unclear, with one possibility being an increased contribution from jet emission at these low luminosities. These observations suggest the James Webb Space Telescope will be a useful tool for detecting the lowest-luminosity AGNs.

Keywords: low-luminosity active galactic nuclei; interferometry; active galactic nuclei; near infrared astronomy