adsabs/SciX_UAT_keywords huggingface dataset:
How Flow Isolation May Set the Mass Scale for Super-Earth Planets

Much recent work on planet formation has focused on the growth of planets by accretion of grains whose aerodynamic properties make them marginally coupled to the nebular gas, a theory commonly referred to as "pebble accretion." While the rapid growth rates of pebble accretion can ameliorate some problems in planet formation theory, they raise new concerns as well. A particular issue is the preponderance of observed planets that end their growth as "super-Earths" or "sub-Neptunes," with masses in the range 2-10 M⊕. Once planets reach this mass scale, growth by pebble accretion is so rapid that ubiquitously ending growth at super-Earth masses is difficult unless growth rates drop at this mass scale. In this work, we highlight this issue in detail using our previously published model of pebble accretion, and also propose a reason for this change in growth rate: feedback between the growing planet's atmosphere and the gas disk inhibits accretion of smaller particle sizes by forcing them to flow around the growing planet instead of being accreted. For reasonable fiducial disk parameters, this "flow isolation" will inhibit accretion of all available particle sizes once the planet reaches super-Earth masses. We also demonstrate that the characteristics of this "flow isolation mass" agree with previously published trends identified in the Kepler planets.

Keywords: exoplanets; planetary system formation; protoplanetary disks; super earths
Effects of Stellar Feedback on Stellar and Gas Kinematics of Star-forming Galaxies at 0.6 < z < 1.0

Recent zoom-in cosmological simulations have shown that stellar feedback can flatten the inner density profile of the dark matter halo in low-mass galaxies. A correlation between the stellar/gas velocity dispersion (σstar, σgas) and the specific star formation rate (sSFR) is predicted as an observational test of the role of stellar feedback in re-shaping the dark matter density profile. In this work we test the validity of this prediction by studying a sample of star-forming galaxies at 0.6 < z < 1.0 from the LEGA-C survey, which provides high signal-to-noise measurements of stellar and gas kinematics. We find that a weak but significant correlation between σstar (and σgas) and sSFR indeed exists for galaxies in the lowest mass bin (M* ∼ 1010 M⊙). This correlation, albeit with a ∼35% scatter, holds for different tracers of star formation, and becomes stronger with redshift. This result generally agrees with the picture that at higher redshifts star formation rate was generally higher, and galaxies at M* ≲ 1010 M⊙ have not yet settled into a disk. As a consequence, they have shallower gravitational potentials more easily perturbed by stellar feedback. The observed correlation between σstar (and σgas) and sSFR supports the scenario predicted by cosmological simulations, in which feedback-driven outflows cause fluctuations in the gravitation potential that flatten the density profiles of low-mass galaxies.

Keywords: galaxy evolution; galaxy kinematics; galaxy dynamics; galaxy dark matter halos; spectroscopy; photometry
The Star Formation Across Cosmic Time (SFACT) Survey. III. Spectroscopy of the Initial Catalog of Emission-line Objects

The Star Formation Across Cosmic Time (SFACT) survey is a new narrowband survey designed to detect emission-line galaxies (ELGs) and quasi-stellar objects (QSOs) over a wide range of redshifts in discrete redshift windows. The survey utilizes the WIYN 3.5 m telescope and the Hydra multifiber positioner to perform efficient follow-up spectroscopy on galaxies identified in the imaging part of the survey. Because the objects in the SFACT survey are selected by their strong emission lines, it is possible to obtain useful spectra for even the faintest of our sources (r ~ 25). Here, we present the 453 objects that have spectroscopic data from the three SFACT pilot-study fields, 415 of which are confirmed ELGs. The methodology for processing and measuring these data is outlined in this paper, and example spectra are displayed for each of the three primary emission lines used to detect objects in the survey (Hα, [O III]λ5007, and [O II]λ3727). Spectra of additional QSOs and nonprimary-emission-line detections are also shown as examples. The redshift distribution of the pilot-study sample is examined, and the ELGs are placed in different emission-line diagnostic diagrams in order to distinguish the star-forming galaxies from the active galactic nuclei.

Keywords: galaxy abundances; blue compact dwarf galaxies; dwarf irregular galaxies; emission line galaxies; galaxy evolution; galaxy spectroscopy; liner galaxies; seyfert galaxies; quasars; starburst galaxies; surveys; star formation
Constraints on Nuclear Saturation Properties from Terrestrial Experiments and Astrophysical Observations of Neutron Stars

Taking into account the terrestrial experiments and the recent astrophysical observations of neutron stars and gravitational-wave signals, we impose restrictions on the equation of state (EoS) for isospin-asymmetric nuclear matter. Using the relativistic mean-field model with SU(3) flavor symmetry, we investigate the impacts of effective nucleon mass, nuclear incompressibility, and slope parameter of nuclear symmetry energy on the nuclear and neutron star properties. It is found that the astrophysical information of massive neutron stars and tidal deformabilities, as well as the nuclear experimental data, plays an important role to restrict the EoS for neutron stars. In particular, the softness of the nuclear EoS due to the existence of hyperons in the core gives stringent constraints on those physical quantities. Furthermore, it is possible to put limits on the curvature parameter of nuclear symmetry energy by means of nuclear and astrophysical calculations.

Keywords: neutron stars; nuclear astrophysics; nuclear physics
Temporal Evolution of the Rotation of the Interplanetary Magnetic Field BX, By, and Bz Components

The daily interplanetary magnetic field (IMF) BX, By, and Bz components from 1967 January 1 to 2018 December 31 listed in the OMNI database are used to investigate their periodicity and study temporal variation of their rotation cycle lengths through continuous wavelet transform, autocorrelation, and cross-correlation analyses. The dominant rotation period in each of the daily BX, By, and Bz components is 27.4 days, implying the existence of rotational modulation in the three time series. The dependence of the rotation cycle lengths for both BX and By components on solar cycle phase almost shows the same result. The rotation cycle lengths for both BX and By components increase from the start to the first year of a new Schwabe cycle, then decrease gradually from the first to the fourth year, and finally fluctuate around the 27.4-day period within a small amplitude from the fourth year to the end of the Schwabe solar cycle. For the Bz component, its rotation cycle length does not show such a solar cycle variation. The significant periods in the variation of BX rotation are 2.9, 3.4, 4.3, 4.9, 10.5, and 11.9 yr, and there exist significant periods of 3.4, 9.9, and 14.1 yr in the variation of By rotation. The relationship of solar activity with BX and By components is complex. The possible mechanisms for the temporal variation of the rotation period of the three components are discussed.

Keywords: interplanetary magnetic fields
Intriguing Drifting Subpulses in the Vela Pulsar

We report on the discovery of drifting subpulses from the Vela pulsar, observed using the Yunnan 40 m radio telescope at 6800 MHz observing frequency. The single pulses show the presence of two distinct drifting patterns, where the central component is modulated in longitude and amplitude simultaneously with a period of 9 pulses, and the trailing component remains phase stationary within the pulse window but periodically changes in intensity with a period of 29 pulses. The leading component emission remains constant in intensity and pulse phase. Such periodic modulation in the Vela pulsar is a separate phenomenon from periodic nulling and traditional subpulse drifting, which may lead to a greater understanding of the pulse emission mechanism.

Keywords: pulsars
Revisiting Emission-line Measurement Methods for Narrow-line Active Galactic Nuclei

Measuring broad emission-line widths in active galactic nuclei (AGN) is not straightforward owing to the complex nature of flux variability in these systems. Line width measurements become especially challenging when the signal-to-noise ratio is low, profiles are narrower, or spectral resolution is low. We conducted an extensive correlation analysis between emission-line measurements from the optical spectra of Markarian 142 (Mrk 142; a narrow-line Seyfert galaxy) taken with the Gemini North Telescope (Gemini) at a spectral resolution of 185.6 ± 10.2 km s-1 and the Lijiang Telescope (LJT) at 695.2 ± 3.9 km s-1 to investigate the disparities in the measured broad-line widths from both telescopes' data. Due to its narrow broad-line profiles, which were severely affected by instrumental broadening in the lower-resolution LJT spectra, Mrk 142 posed a challenge. We discovered that allowing the narrow-line flux of permitted lines having broad and narrow components to vary during spectral fitting caused a leak in the narrow-line flux to the broad component, resulting in broader broad-line widths in the LJT spectra. Fixing the narrow-line flux ratios constrained the flux leak and yielded the Hβ broad-line widths from LJT spectra ~54% closer to the Gemini Hβ widths than with flexible narrow-line ratios. The availability of spectra at different resolutions presented this unique opportunity to inspect how spectral resolution affected emission-line profiles in our data and adopt a unique method to accurately measure broad-line widths. Reconsidering line measurement methods while studying diverse AGN populations is critical for the success of future reverberation-mapping studies. Based on the technique used in this work, we offer recommendations for measuring line widths in narrow-line AGN.

Keywords: active galactic nuclei; spectroscopy
Constraints on the IBEX Ribbon's Origin from Its Evolution over a Solar Cycle

In 2009, the Interstellar Boundary Explorer (IBEX) discovered a narrow "ribbon" of energetic neutral atom emissions across the sky with properties correlated with the solar wind latitudinal structure and the interstellar magnetic field draped around the heliosphere. It is widely believed that the ribbon is formed from the escape of heliospheric ENAs into the local interstellar medium and their eventual return as secondary ENAs. However, there is no consensus on the rate of pitch angle scattering of these PUIs before they become secondary ENAs. We test two opposing limits of scattering rates ("weak" versus "strong") by solving a time-dependent model of the ribbon that evolves with the solar cycle, and we compare them to IBEX observations over 2009-2019. First, we find that both models qualitatively reproduce the evolution of IBEX fluxes for most of the data set, with a few exceptions, although the strong (or "spatial retention") scattering model greatly underestimates the observed fluxes. Regardless, time dependence of fluxes cannot distinguish these models. Second, the ribbon's geometric properties, i.e., its center and radius, are significantly different between the models. The spatial retention model reproduces the observed ribbon centers as a function of energy and time slightly better than the weak scattering model, and the spatial retention model reproduces the observed ribbon radius over energy and time almost perfectly, whereas the weak scattering model compares poorly. Our analysis favors the spatial retention mechanism as the source of the IBEX ribbon, but it requires modification to increase the flux of ENAs observed at 1 au.

Keywords: space plasmas; heliosphere; solar wind; pickup ions; interstellar magnetic fields; solar cycle
Association Between Magnetic Pressure Difference and the Movement of Solar Pores

Solar pores are closely related to the concentration, dissipation, and transportation of solar magnetic flux. Their observable characteristics can provide constraints on models and simulations of magnetic flux emergence and formation. The specific property investigated in this study is their horizontal movement. The aim is to investigate whether the movement is correlated with any observable quantities. Our statistical analysis of 61 compact pores identified from the Spaceweather HMI Active Region Patches (SHARP) from 2011 to 2018 indicates that the direction of movement is often either parallel or antiparallel to the direction of maximum magnetic pressure difference (dP mag) at the opposite sides of the edges of the pores. The correlation coefficients for both the parallel and antiparallel cases are higher than 0.74. Despite the high correlation, our analysis using the transfer entropy indicates no significant causal relationship between the direction of motion and the direction of maximum dP mag.

Keywords: solar physics; solar activity; solar active regions; solar active region magnetic fields; solar magnetic fields; solar magnetic flux emergence
Two Candidate Pulsar TeV Halos Identified from Property-similarity Studies

Teraelectronvolt halos have been suggested to be a common phenomenon associated with middle-aged pulsars. Based on our recent work on the middle-aged pulsar J0631+1036, which is the only known source positionally coincident with a hard teraelectronvolt γ-ray source and likely powers the latter as a teraelectronvolt halo, we select three candidate teraelectronvolt halos from the first Large High Altitude Air Shower Observatory (LHAASO) catalog of γ-ray sources. The corresponding pulsars, given by the positional coincidences and property similarities, are PSR J1958+2846, PSR J2028+3332, and PSR J1849-0001. We analyze the gigaelectronvolt γ-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope for the first two pulsars, as the last is γ-ray quiet. We remove the pulsed emissions of the pulsars from the source regions from timing analysis, and determine that there are no residual gigaelectronvolt emissions in the regions as any possible counterparts to the teraelectronvolt sources. Considering the previous observational results for the source regions and comparing the two pulsars to Geminga (and Monogem), the LHAASO-detected teraelectronvolt sources are likely the pulsars' respective teraelectronvolt halos. We find that the candidate and identified teraelectronvolt halos, including that of PSR J1849-0001, have luminosities at 50 TeV (estimated from the differential fluxes) approximately proportional to the spin-down energy $\dot{E}$ of the pulsars, and the ratios of the former to the latter are ~6 × 10-4.

Keywords: gamma-ray sources; pulsars
Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background

The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1σ. The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we "extended" each PTA's data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings–Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA's Data Release 3, which will involve not just adding in additional pulsars but also including data from all three PTAs where any given pulsar is timed by more than a single PTA.

Keywords: gravitational waves; pulsars
Dimorphos's Orbit Period Change and Attitude Perturbation due to Its Reshaping after the DART Impact

On 2022 September 26 (UTC), NASA's Double Asteroid Redirection Test (DART) mission achieved a successful impact on Dimorphos, the secondary component of the near-Earth binary asteroid system (65803) Didymos. Subsequent ground-based observations suggest a significant reshaping of Dimorphos, with its equatorial axis ratio changing from 1.06 to ∼1.3. Here we report the effects of this reshaping event on Dimorphos's orbit and attitude. Given the reported reshaping magnitude, our mutual dynamics simulations show that approximately 125 s of the observed 33 minute orbit period change after the DART impact may have resulted from reshaping. This value, however, is sensitive to the precise values of Dimorphos's post-impact axis ratios and may vary by up to 2 times that amount, reaching approximately 250 s within the current uncertainty range. While the rotational state of the body is stable at the currently estimated axis ratios, even minor changes in these ratios or the introduction of shape asymmetry can render its attitude unstable. The perturbation to Dimorphos's orbital and rotational state delivered by the impact directly, combined with any reshaping, leads to a strong possibility for a tumbling rotation state. To accurately determine the momentum enhancement factor (β) through measurements by the European Space Agency's Hera spacecraft and to evaluate the effectiveness of the kinetic deflection technique for future planetary defense initiatives, the effects of reshaping should not be overlooked.

Keywords: near-earth objects; asteroid satellites; asteroid dynamics; two-body problem; asteroid rotation; gravitational interaction; accelerating universe; planetary science
A Complex Luminosity Function for the Anomalous Globular Clusters in NGC 1052-DF2 and NGC 1052-DF4

NGC 1052-DF2 and NGC 1052-DF4 are ultradiffuse galaxies that have extremely low velocity dispersions, indicating that they have little or no dark matter. Both galaxies host anomalously luminous globular clusters (GCs), with a peak magnitude of their GC luminosity function (GCLF) that is ∼1.5 mag brighter than the near-universal value of MV ≈ -7.5. Here we present an analysis of the joint GCLF of the two galaxies, making use of new Hubble Space Telescope photometry and Keck spectroscopy and a recently improved distance measurement. We apply a homogeneous photometric selection method to the combined GC sample of DF2 and DF4. The new analysis shows that the peak of the combined GCLF remains at MV ≈ -9 mag. In addition, we find a subpopulation of less luminous GCs at MV ≈ -7.5 mag, where the near-universal GCLF peak is located. The number of GCs in the magnitude range of -5 to -8 is ${7}_{-4}^{+7}$ <!-- --> in DF2 and ${9}_{-5}^{+8}$ <!-- --> in DF4, similar to that expected from other galaxies of the same luminosity. The total GC number between MV of -5 and -11 is ${19}_{-4}^{+9}$ <!-- --> for DF2 and ${19}_{-5}^{+9}$ <!-- --> for DF4, calculated from the background-subtracted GCLF. The data are consistent with both galaxies having two GC populations: the one expected for their luminosity, and a very luminous population composing ∼90% of the total cluster mass. The number of GCs does not scale with the halo mass in either DF2 or DF4, suggesting that NGC is not directly determined by the merging of halos.

Keywords: globular star clusters; low surface brightness galaxies; galaxy structure
Intermittency of Magnetic Discontinuities in the Near-Sun Solar Wind Turbulence

The intermittency domain is in the magnetohydrodynamic inertial range but just above the dissipation range and contains the intermittent structures that influence the spectral index. However, the nature of these structures is still under debate and how they affect the higher-order scaling behavior in the near-Sun solar wind turbulence remains to be investigated. Here we use the magnetic field data measured by Parker Solar Probe in the near-Sun solar wind. We identify the intermittency by partial variance of increments method and conduct the multiorder structure functions analyses in the intermittency domain before and after removing the intermittency. We also perform for the first time the scaling analyses on the fluctuations of magnetic field direction given by the rotational angle $\theta ={\cos }^{-1}({{\boldsymbol{B}}}_{1}\cdot {{\boldsymbol{B}}}_{2})/| {{\boldsymbol{B}}}_{1}| | {{\boldsymbol{B}}}_{2}| $ , in which B 1 and B 2 are the magnetic fields measured at two instants. We find that the multifractal scaling of the magnetic field could be predicted by the log-Poisson intermittency model with 2D sheetlike structures and a simple Kolmogorov -5/3 monoscaling recovers after the removal of the intermittency. We also find a similar behavior for the scalings of θ, suggesting that magnetic discontinuities are involved in the energy transfer process of solar wind turbulence.

Keywords: solar wind; interplanetary turbulence; magnetohydrodynamics; heliosphere
Intraday Mid-infrared Variability of PMN J0948+0022 on 2020 April 26

We report a new period mid-infrared variability of PMN J0948+0022 on 2020 April 26, observed by the Wide-field Infrared Survey Explore (WISE). This source faded consistently over a period of one day. The amplitude of variability is about 0.21 and 0.18 mag in the W1 (3.4 μm) and W2 (4.6 μm) bands, respectively. The intraday variability constrains the size of the mid-infrared emission region to about 5 × 10-4 pc, which is rather smaller than that of the dust torus but consistent with the base of a jet. The mid-infrared color showed a significant bluer-when-brighter trend, similar to γ-ray emitting blazars. These characteristics suggest that the mid-infrared emission was dominated by the synchrotron emission of relativistic electrons in the jet.

Keywords: infrared photometry; seyfert galaxies; relativistic jets