Sazuna/UAT_keywords huggingface dataset:
Radio Observations of Two Intermittent Pulsars: PSRs J1832+0029 and J1841-0500. We present long-term observations of two intermittent pulsars, PSRs J1832+0029 and J1841-0500, using the Parkes 64 m radio telescope. The radio emission for these pulsars switches off for year-long durations. Our new observations have enabled us to improve the determination of the on-off timescales and the spin-down rates during those emission states. In general our results agree with previous studies of these pulsars, but we now have significantly longer data spans. We have identified two unexpected signatures in the data. Weak emission was detected in a single observation of PSR J1832+0029 during an off emission state. For PSR J1841-0500, we identified a quasi-periodic fluctuation in the intensities of the detectable single pulses, with a modulation period between 21 and 36 pulse periods.

Keywords: Radio pulsars, Pulsar timing method, Pulsars
New Radio Constraints on the Obscured Star Formation Rates of Massive GRB Hosts at Redshifts 2-3.5. It is not clear whether gamma-ray bursts (GRBs) are unbiased tracers of cosmic star formation at z &gt; 2. Since dusty starburst galaxies are significant contributors to the cosmic star formation at these redshifts, they should form a major part of the GRB host population. However, recent studies at z ≤ 2 have shown that the majority of the star formation activity in GRB hosts is not obscured by dust. Here, we investigate the galaxy-scale dust obscuration in z ∼ 2-3.5 GRB hosts preselected to have high-resolution, high signal-to-noise afterglow spectra in the rest-frame ultraviolet (UV) and thus relatively low line-of-sight dust obscuration. We present new deep Very Large Array observations of four GRB hosts, and compare the radio-based (upper limits on the) total star formation rates (SFRs) to the unobscured SFRs derived from fits to the optical-UV spectral energy distribution. The fraction of the total SFR that is obscured by dust in these galaxies is found to be &lt;90% in general, and ≲50% for GRB 021004 in particular. These observations suggest that z ∼ 2-3.5 GRBs with UV-unobscured sightlines originate in star-forming galaxies with low overall dust obscuration, unlike the dusty starburst population.

Keywords: Gamma-ray bursts, Galaxy properties, Interstellar dust extinction, Star formation, Galaxy evolution
Doppler Factor Estimation for Fermi Blazars. In this work, we exploit the luminosity of the broad-line region (BLR) for 50 Fermi blazars through matching the coordinates between the Sloan Digital Sky Survey catalog, Fermi Large Area Telescope Third Source Catalog, and the Fermi Large Area Telescope Fourth Source Catalog and fitting their emission lines. In total, we collected a sample of 350 blazars with broad-line emissions including 50 new objects and 300 blazars from published works to revisit the correlation between the γ-ray luminosity and the broad-line luminosity, and proposed a new method to estimate the Doppler factors based on the correlation between the radiative power of the jet and luminosity of the BLR. We come to following conclusions. (1) For the 50 Fermi blazars, their broad-line luminosity (log LBLR) ranges from 41.82-45.2 erg s-1 with a mean value of 44.39 erg s-1. (2) The Doppler factor (δ) ranges from δ = 0.35 to δ = 85.66 with a mean value of 12.54, which is consistent with the results in the literature. (3) There are positive correlations between γ-ray luminosity and broad-line luminosity, and between γ-ray luminosity and the Doppler factor.

Keywords: Blazars, Active galactic nuclei, Jets, High energy astrophysics
Multiepoch VLBI of L Dwarf Binary 2MASS J0746+2000AB: Precise Mass Measurements and Confirmation of Radio Emission from Both Components. Surveys have shown that up to 1/10th of all ultracool dwarfs (UCDs) are appreciable radio emitters, with their emission attributed to a combination of gyrosynchrotron radiation and the electron cyclotron maser instability. 2M J0746+2000AB is a close stellar binary comprised of an L0 and L1.5 dwarf that was previously identified as a source of 5 GHz radio emission. We used Very Long Baseline Interferometry (VLBI) to precisely track the radio emission over seven epochs in 2010-2017, and found both components to be radio emitters—the first such system identified—with the secondary component as the dominant source of emission in all epochs. The previously identified 2.07 hr periodic bursts were confirmed to originate from the secondary component, although an isolated burst was also identified from the primary component. We additionally fitted the VLBI absolute astrometric positions jointly with existing relative orbital astrometry derived from optical/infrared observations with Markov Chain Monte Carlo methods to determine the orbital parameters of the two components. We found the masses of the primary and secondary optical components to be 0.0795 ± 0.0003 M⊙, and 0.0756 ± 0.0003 M⊙, respectively, representing the most precise mass estimates of any UCDs to date. Finally, we place a 3σ upper limit of 0.9 Mjup au on the mass and separation of planets orbiting either of the two components.

Keywords: Close binary stars, Low mass stars, Radio astrometry, Stellar magnetic fields
Evidence for Resonance Scattering in the X-Ray Grating Spectrum of the Supernova Remnant N49. Resonance scattering (RS) is an important process in astronomical objects, because it affects measurements of elemental abundances and distorts surface brightness of the object. It is predicted that RS can occur in plasmas of supernova remnants (SNRs). Although several authors reported hints of RS in SNRs, no strong observational evidence has been established so far. We perform a high-resolution X-ray spectroscopy of the SNR N49 with the Reflection Grating Spectrometer on board XMM-Newton. The Reflection Grating Spectrometer spectrum of N49 shows a high G-ratio of O VII Heα lines as well as O VIII Lyβ/α and Fe XVII (3s-2p)/(3d-2p) ratios, which cannot be explained by the emission from a thin thermal plasma. These line ratios can be well explained by the effect of RS. Our result implies that RS has a large impact particularly on a measurement of the oxygen abundance.

Keywords: Supernova remnants, Interstellar medium, High energy astrophysics, X-ray sources
On the Paradoxical Impact of Blending by Red Clump Giants. The impact of blending by red clump giants (RCGs; or relatively metal-rich red horizontal branch stars) is discussed as it relates to RRab and classical Cepheids, and invariably establishing an improved distance scale. An analysis of Magellanic Cloud variables reaffirms that blending with RCGs may advantageously thrust remote extragalactic stars into the range of detectability. Specifically, simulations of Magellanic Cloud RRab and RCG blends partly reproduce bright non-canonical trends readily observed in amplitude-magnitude space (Ic versus ${A}_{{I}_{c}}$ ). Conversely, the larger magnitude offset between classical Cepheids and RCGs causes the latter's influence to be challenging to address. The relative invariance of a Wesenheit function's slope to metallicity (e.g., ${W}_{{{VI}}_{c}}$ ) implies that a deviation from the trend could reveal blending and photometric inaccuracies (e.g., standardization), as blending by RCGs (a proxy of an evolved red stellar demographic) can flatten period-Wesenehit relations owing to the increased impact on less-luminous shorter-period Cepheids. That could partly explain both a shallower inferred Wesenheit function and overestimated H0 values. A consensus framework to identify and exploit blending is desirable, as presently H0 estimates from diverse teams are unwittingly leveraged without homogenizing the disparate approaches (e.g., no blending correction to a sizable $\simeq 0\buildrel{\rm{m}}\over{.} 3$ ).

Keywords: Galaxy distances, Red giant clump, Hubble constant, RR Lyrae variable stars, Cepheid variable stars, Photometry, Stellar distance
Weak-lensing Peak Statistics in Mocks by the Inverse-Gaussianization Method. Recent studies have shown the great power of peak counts in weak-lensing maps. In this work, we apply the inverse-Gaussianization method proposed in Yu et al. to produce weak-lensing convergence maps quickly and investigate the peak statistics, including the peak height counts and peak steepness counts in these mocks. The distributions of peak height and steepness are in good agreement with the simulation results. The difference is ≲20% for these peak statistics in the maps at source redshift zs = 1. Also, the loss of off-diagonal elements in the peak covariance motivates us to consider the super-sample variance in weak-lensing peak statistics. We propose four correction methods to effectively recover the (anti)correlation among different bins by adding different scatters in the mean value of these mocks. Finally, as an example of the application, we adopt the improved inverse-Gaussianization method to quickly generate 40,000 mocks to calculate precision matrices for the power spectrum and peak-statistics joint analysis.

Keywords: Weak gravitational lensing, Non-Gaussianity, Cosmology, Large-scale structure of the universe
RedMaPPer: Evolution and Mass Dependence of the Conditional Luminosity Functions of Red Galaxies in Galaxy Clusters. We characterize the luminosity distribution, halo-mass dependence, and redshift evolution of red galaxies in galaxy clusters using the SDSS Data Release 8 redMaPPer cluster sample. We propose a simple prescription for the relationship between the luminosity of both red central and red satellite galaxies and the mass of their host halos, and show that this model is well fit by the data. Using a larger galaxy cluster sample than previously employed in the literature, we find that the luminosities of red central galaxies scale as $\langle \mathrm{log}L\rangle \propto {A}_{L}\mathrm{log}({M}_{200b})$ , with AL = 0.39 ± 0.04, and that the scatter of the red central galaxy luminosity at fixed M200b ( ${\sigma }_{\mathrm{log}L| M}$ ) is ${0.23}_{-0.04}^{+0.05}$ dex, with the error bar including systematics due to mis-centering of the cluster finder, photometry, and photometric redshift estimation. Our data prefers a positive correlation between the luminosity of red central galaxies and the observed richness of clusters at a fixed halo mass, with an effective correlation coefficient ${d}_{\mathrm{eff}}={0.36}_{-0.16}^{+0.17}$ . The characteristic luminosity of red satellites becomes dimmer from z = 0.3 to z = 0.1 by ∼20% after accounting for passive evolution. We estimate the fraction of galaxy clusters where the brightest red galaxy is not the central to be PBNC ∼ 20%. We discuss implications of these findings in the context of galaxy evolution and the galaxy-halo connection.

Keywords: Galaxy clusters, Galaxy dark matter halos, Galaxy evolution, Large-scale structure of the universe
Global Energetics of Solar Flares. XI. Flare Magnitude Predictions of the GOES Class. In this study we determine scaling relationships of observed solar flares that can be used to predict upper limits of the Geostationary Orbiting Earth Satellite (GOES)-class magnitude of solar flares. The flare prediction scheme is based on the scaling of the slowly varying potential energy Ep(t), which is extrapolated in time over an interval of Δt ≤ 24 hr. The observed scaling of the dissipated energy Ediss scales with the potential field energy as ${E}_{\mathrm{diss}}\propto {E}_{p}^{1.32}$ . In addition, the observed scaling relationship of the flare volume, $V\propto {E}_{\mathrm{diss}}^{1.17}$ , the multi-thermal energy, Eth ∝ V0.76, the flare emission measure $(\mathrm{EM})\propto {E}_{\mathrm{th}}^{0.79}$ , the EM-weighted temperature Tw, and the GOES flux, ${F}_{8}{(t)\propto {E}_{p}(t)}^{0.92}$ , allows us then to predict an upper limit of the GOES-class flare magnitude in the extrapolated time window. We find a good correlation (cross-correlation coefficient (CCC) ≈ 0.7) between the observed and predicted GOES-class flare magnitudes (in 172 X- and M-class events). This is the first algorithm that employs observed scaling laws of physical flare parameters to predict GOES flux upper limits, an important capability that complements previous flare prediction methods based on machine-learning algorithms used in space-weather forecasting.

Keywords: Solar physics, Solar flares
Cosmological Information from the Small-scale Redshift-space Distortion. The redshift-space distortion (RSD) in the observed distribution of galaxies is known as a powerful probe of cosmology. Observations of large-scale RSD, caused by the coherent gravitational infall of galaxies, have given tight constraints on the linear growth rate of the large-scale structures in the universe. On the other hand, the small-scale RSD, caused by galaxy-random motions inside clusters, has not been much used in cosmology, but it also has cosmological information because universes with different cosmological parameters have different halo mass functions and virialized velocities. We focus on the projected correlation function w(rp) and the multipole moments ξl on small scales (1.4-30 h-1 Mpc). Using simulated galaxy samples generated from a physically motivated most bound particle (MBP)-galaxy correspondence scheme in the Multiverse Simulation, we examine the dependence of the small-scale RSD on the cosmological matter density parameter Ωm; the satellite velocity bias with respect to MBPs, ${b}_{V}^{s}$ ; and the merger timescale parameter α. We find that α = 1.5 gives an excellent fit to the w(rp) and ξl measured from the Sloan Digital Sky Survey-Korea Institute for Advanced Study value-added galaxy catalog. We also define the "strength" of the Fingers of God as the ratio of the parallel and perpendicular size of the contour in the two-point correlation function set by a specific threshold value and show that the strength parameter helps constrain $({{\rm{\Omega }}}_{m},{b}_{V}^{s},\alpha )$ by breaking the degeneracy among them. The resulting parameter values from all measurements are $({{\rm{\Omega }}}_{m},{b}_{V}^{s})=(0.272\pm 0.013,0.982\pm 0.040)$ , indicating a slight reduction of satellite galaxy velocity relative to the MBP. However, considering that the average MBP speed inside halos is 0.94 times the dark matter velocity dispersion, the main drivers behind the galaxy velocity bias are gravitational interactions, rather than baryonic effects.

Keywords: Redshift surveys, N-body simulations, Cosmological parameters from large-scale structure
Untangling Optical Emissions of the Jet and Accretion Disk in the Flat-spectrum Radio Quasar 3C 273 with Reverberation Mapping Data. 3C 273 is an intensively monitored flat-spectrum radio quasar with both a beamed jet and blue bump together with broad emission lines. The coexistence of the comparably prominent jet and accretion disk leads to complicated variability properties. Recent reverberation mapping monitoring for 3C 273 revealed that the optical continuum shows a distinct long-term trend that does not have a corresponding echo in the Hβ fluxes. We compile multiwavelength monitoring data from the Swift archive and other ground-based programs and clearly find two components of emissions at optical wavelength. One component stems from the accretion disk itself, and the other component can be ascribed to the jet contribution, which also naturally accounts for the nonechoed trend in reverberation mapping data. We develop an approach to decouple the optical emissions from the jet and accretion disk in 3C 273 with the aid of multiwavelength monitoring data. By assuming that the disk emission has a negligible polarization in consideration of the low inclination of the jet, the results show that the jet contributes a fraction of ∼10% at the minimum and up to ∼40% at the maximum to the total optical emissions. This is the first time to provide a physical interpretation of the "detrending" manipulation conventionally adopted in reverberation mapping analysis. Our work also illustrates the importance of appropriately analyzing variability properties in cases of coexisting jets and accretion disks.

Keywords: Radio jets, Quasars, Reverberation mapping, Active galaxies, Radio galaxies
Gravitational-wave Memory from a Propagating Relativistic Jet: A Probe of the Interior of Gamma-Ray Burst Progenitors. It is believed that the relativistic jets of gamma-ray bursts (GRBs) should initially propagate through a heavy envelope of the massive progenitor stars or through merger ejecta formed from compact binary mergers. The interaction of a jet with a stellar envelope or merger ejecta can lead to the deceleration of the head material of the jet and simultaneously the formation of a hot cocoon. However, this jet-envelope/ejecta interaction is actually undetectable with electromagnetic radiation and can only be inferred indirectly by the structure of the breakout jet. Therefore, as a solution to this phenomenon, we suggest the jet-envelope/ejecta interaction can produce a gravitational-wave (GW) memory of an amplitude of $h\sim {10}^{-26}\mbox{--}{10}^{-23}$ , which could be detected with some future GW detectors sensitive in the frequency range from sub-Hertz to several tens of Hertz. This provides a potential direct way to probe the jet propagation and then the interior of the GRB progenitors.

Keywords: Shocks, Relativistic jets, Gravitational waves, Gamma-ray bursts
Kilonova Emission from Black Hole-Neutron Star Mergers. I. Viewing-angle-dependent Lightcurves. In this paper, we explore the viewing angle effect on black hole-neutron star (BH-NS) merger kilonova lightcurves. We extrapolate the fitting formulae for the mass and velocity of dynamical ejecta across a wide mass ratio range validated with 66 simulations and use them in kilonova lightcurve calculations. The calculated peak luminosity of a BH-NS merger kilonova is typically about a few times 1041 erg s-1, which is always ≲4.5 × 1041 erg s-1. This corresponds to AB absolute magnitudes fainter than ∼-15 mag in the optical and ∼-16 mag in the infrared. The dynamical ejecta usually contribute to the majority of the kilonova emission, as its projected photosphere area is much larger than that of the disk wind outflows. The fitted blackbody temperature and the observed multiband lightcurve shape are insensitive to the line of sight. The peak time of the observed multiband lightcurves, affected by the light-propagation effect, is related to the relative motion direction between the dynamical ejecta and the observer. The predicted peak luminosity, which changes with the projected photosphere area, only varies by a factor of ∼(2-3) (or by ∼1 mag) for different viewing angles. When taking the short-duration gamma-ray burst afterglow into account, for an on-axis geometry, the kilonova emission is usually outshone by the afterglow emission and can only be observed in the redder bands, especially in the K band at late times. Compared with GW 170817/AT 2017gfo, BH-NS merger kilonovae are optically dim but possibly infrared bright, and have lower fitting temperature at the same epoch after the merger.

Keywords: Neutron stars, Gamma-ray bursts, Gravitational waves, Black holes
N-body Simulations of the Ring Formation Process around the Dwarf Planet Haumea. Haumea is the only known trans-Neptunian object with a ring. The ring is in a position that causes a 3:1 spin-orbit resonance with the rotational period of Haumea, which has a triaxial shape. The non-axisymmetric gravitational field around Haumea is thought to affect the dynamics of the ring; however, the process of ring formation has not been elucidated. In this study, we analyze in some detail a potential ring formation scenario for Haumea. We first calculated the gravitational field around the triaxial ellipsoid and estimated the distance at which an object revolving around Haumea can exist stably using a simulation that incorporated the time-varying gravitational field. The results of this simulation showed that the trajectory of the object became unstable just inside its current ring position. Next, we analytically derived the Roche radius for a rigid body revolving around a triaxial ellipsoid and showed that the Roche radius could be near the current ring position. Furthermore, as a parameter study, we performed N-body simulations using the coefficient of rubble-pile restitution as a variable. Results demonstrated that, according to numerous parameters, the position of the Roche radius was near the current position of Haumea's ring. Based on these findings, we can assume that there is a high possibility that the ring formed in the region between the boundary of the unstable region of the orbit and the Roche radius. The scenario presented in this study could help explain the process by which Haumea's ring formed.

Keywords: Solar system formation, Solar system, Planetary rings, Dwarf planets, N-body simulations
Search for Continuous Gravitational Waves from the Central Compact Objects in Supernova Remnants Cassiopeia A, Vela Jr., and G347.3-0.5. We perform a sub-threshold follow-up search for continuous nearly monochromatic gravitational waves from the central compact objects associated with the supernova remnants (SNRs) Vela Jr., Cassiopeia A, and SNR G347.3-0.5. Across the three targets, we investigate the most promising ≍10,000 combinations of gravitational-wave frequency and frequency derivative values, based on the results from an Einstein@Home search of the LIGO O1 observing run data, dedicated to these objects. The selection threshold is set so that a signal could be confirmed using the newly released O2 run LIGO data. In order to achieve best sensitivity we perform two separate follow-up searches, on two distinct stretches of the O2 data. Only one candidate survives the first O2 follow-up investigation, associated with the central compact object in SNR G347.3-0.5, but it is not conclusively confirmed. In order to assess a possible astrophysical origin we use archival X-ray observations and search for amplitude modulations of a pulsed signal at the putative rotation frequency of the neutron star and its harmonics. This is the first extensive electromagnetic follow-up of a continuous gravitational-wave candidate performed to date. No significant associated signal is identified. New X-ray observations contemporaneous with the LIGO O3 run will enable a more sensitive search for an electromagnetic counterpart. A focused gravitational-wave search in O3 data based on the parameters provided here should be easily able to shed light on the nature of this outlier. Noise investigations on the LIGO instruments could also reveal the presence of a coherent contamination.

Keywords: Gravitational wave sources, Pulsars, Supernova remnants, Gravitational wave astronomy, Gravitational waves