Sazuna/UAT_keywords huggingface dataset:
Lyman Continuum Escape Fraction from Low-mass Starbursts at z = 1.3. We present a new constraint on the Lyman continuum (LyC) escape fraction at $z\sim 1.3$ . We obtain deep, high sensitivity far-UV imaging with the Advanced Camera for Surveys Solar Blind Channel on the Hubble Space Telescope, targeting 11 star-forming galaxies at 1.2 &lt; z &lt; 1.4. The galaxies are selected from the 3D-HST survey to have high Hα equivalent width (EW) with an EW &gt; 190 Å, low stellar mass (M* &lt; 1010 M☉), and U-band magnitude of U &lt; 24.2. These criteria identify young, low metallicity star-bursting populations similar to the early star-forming galaxies believed to have reionized the universe. We do not detect any LyC signal (with a signal-to-noise ratio &gt; 3) in the individual galaxies or in the stack in the far-UV images. We place 3σ limits on the relative escape fraction of individual galaxies to be ${f}_{\mathrm{esc},\mathrm{rel}}\lt [0.10\mbox{--}0.22]$ and a stacked 3σ limit of ${f}_{\mathrm{esc},\mathrm{rel}}\lt 0.07$ . Measuring various galaxy properties, including stellar mass, dust attenuation, and star formation rate, we show that our measured values fall within the broad range of values covered by the confirmed LyC emitters from the literature. In particular, we compare the distribution of Hα and [O III] EWs of confirmed LyC emitters and non-detections, including the galaxies in this study. Finally, we discuss if a dichotomy seen in the distribution of Hα EWs can perhaps distinguish the LyC emitters from the non-detections. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Keywords: Starburst galaxies, Emission line galaxies, Ultraviolet astronomy, Galaxy evolution, Intergalactic medium, Reionization, High-redshift galaxies
On the Use of Naked-eye Sunspot Observations during the Maunder Minimum. Naked-eye sunspot observations (NESOs) have been recorded for the past two millennia, approximately. These kinds of records were made around the world, mainly in Asian civilizations, and they are compiled in several catalogs. In this work, we analyze solar activity on days of the 19th century when NESOs were recorded. We found that only more than five sunspot groups were recorded in 39% of days corresponding to these NESO events. Furthermore, regarding the largest groups observed on days when NESOs were reported, we show that the uncorrected areas of these groups were below 200 millionths of solar disk (msd) in 3.2% of total cases, while it is 12.9% for areas between 200 and 499 msd. Thus, NESO records do not necessarily imply high solar activity and big sunspot groups. Therefore, these results contradict the interpretations of recent works that, using the same NESO set, suggest the solar activity level during the Maunder Minimum is still an open question. NESO records support the Maunder Minimum as a very low solar activity period.

Keywords: Solar activity, Sunspots, Maunder minimum
Two Portions of the Sagittarius Stream in the LAMOST Complete Spectroscopic Survey of Pointing Area at the Southern Galactic Cap. We constructed a sample of 13,798 stars with Teff, log g, [Fe/H], radial velocity, proper motions, and parallaxes from LAMOST DR5 and Gaia DR2 in the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) at the Southern Galactic Cap consisting of areas A and B. Using the distributions in both proper motions and radial velocity, we detected very significant overdensities in these two areas. These substructures most likely are portions of the Sagittarius (Sgr) stream. With the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, 220 candidates stream members were identified. Based upon distance to the Sun and published models, 106 of these stars are likely to be the members of the Sgr stream. The abundance pattern of these members using [α/Fe] from Xiang et al. were found to be similar to Galactic field stars with [Fe/H] &lt; -1.5 and deficient to Milky Way populations at similar metallicities with [Fe/H] &gt; -1.0. No vertical and only small radial gradients in metallicity along the orbit of the Sgr stream were found in our Sgr stream candidates.

Keywords: Stellar abundances, Galaxy kinematics
Activity Complexes and a Prominent Poleward Surge during Solar Cycle 24. Long-lasting activity complexes (ACs), characterized as a series of closely located, continuously emerging solar active regions (ARs), are considered generating prominent poleward surges from observations. The surges lead to significant variations of the polar field, which are important for the modulation of solar cycles. We aim to study a prominent poleward surge during solar cycle 24 on the southern hemisphere, and analyze its originating ACs and the effect on the polar field evolution. We automatically identify and characterize ARs based on synoptic magnetograms from the Solar Dynamics Observatory. We assimilate these ARs with realistic magnetic configuration into a surface flux transport model, and simulate the creation and migration of the surge. Our simulations well reproduce the characteristics of the surge and show that the prominent surge is mainly caused by the ARs belonging to two ACs during Carrington rotations 2145-2159 (2013 December-2015 January). The surge has a strong influence on the polar field evolution of the southern hemisphere during the latter half of cycle 24. Without the about one-year-long flux emergence in the form of ACs, the polar field around the cycle minimum would have remained at a low level and even reversed to the polarity at cycle 23 minimum. Our study also shows that the long-lived unipolar regions due to the decay of the earlier emerging ARs cause an intrinsic difficulty of automatically identifying and precisely quantifying later emerging ARs in ACs.

Keywords: Solar cycle, Solar active regions, Solar magnetic fields
Internetwork Magnetic Fields Seen in Fe I 1564.8 nm Full-disk Images. We studied the properties of internetwork magnetic fields in the solar photosphere, taking advantage of full-disk Stokes V/I maps of the Fe I 1564.8 nm line, which were obtained during 2010-2019. In contrast to most previous studies, we used data with moderate spatial and spectral resolutions. Nonetheless, we were able to distinguish the internetwork field components and the active region/network boundary components using large Zeeman splitting of the Fe I 1564.8 nm line. Thus, our analysis provides a point of view quite different from that of previous studies. We analyzed the data statistically without ordinary inversions, yet we successfully derived some properties of internetwork fields; the internetwork is filled with small-scale magnetic fields, their strength is within the weak field regime of the Fe I 1564.8 nm line (300-400 G or less), and the internetwork fields are highly inclined. Although the results were obtained from the analysis performed from a different perspective, they are consistent with the majority of previous findings. In addition, no notable variation in the properties of the internetwork fields was found during the period covering most of solar cycle 24.

Keywords: Solar magnetic fields, Spectropolarimetry, Solar photosphere, Near infrared astronomy
Recurrent Galactic Cosmic-Ray Flux Modulation in L1 and Geomagnetic Activity during the Declining Phase of the Solar Cycle 24. Short-term variations (&lt;1 month) of the galactic cosmic-ray (GCR) flux in the inner heliosphere are mainly associated with the passage of high-speed solar wind streams (HSS) and interplanetary (IP) counterparts of coronal mass ejections (ICMEs). Data gathered with a particle detector flown on board the ESA LISA Pathfinder (LPF) spacecraft, during the declining part of solar cycle 24 (2016 February-2017 July) around the Lagrange point L1, have allowed us to study the characteristics of recurrent cosmic-ray flux modulations above 70 MeV n-1. It is shown that the amplitude and evolution of individual modulations depend in a unique way on both IP plasma parameters and particle flux intensity before HSS and ICME transit. By comparing the LPF data with those gathered contemporaneously with the magnetic spectrometer experiment AMS-02 on board the International Space Station and with those of Earth's polar neutron monitors, the GCR flux modulation was studied at different energies during recurrent short-term variations. It is also aimed to set the near real-time particle observation requirements to disentangle the role of long- and short-term variations of the GCR flux to evaluate the performance of high-sensitivity instruments in space such as the future interferometers for gravitational wave detection. Finally, the association between recurrent GCR flux variation observations in L1 and weak to moderate geomagnetic activity in 2016-2017 is discussed. Short-term recurrent GCR flux variations are good proxies of recurrent geomagnetic activity when the Bz component of the IP magnetic field is directed north.

Keywords: Interplanetary medium, Solar rotation, Heliosphere, Cosmic ray detectors, Interferometers, Solar-terrestrial interactions
A Measurement of the CMB E-mode Angular Power Spectrum at Subdegree Scales from 670 Square Degrees of POLARBEAR Data. We report a measurement of the E-mode polarization power spectrum of the cosmic microwave background (CMB) using 150 GHz data taken from 2014 July to 2016 December with the POLARBEAR experiment. We reach an effective polarization map noise level of $32\,\mu {\rm{K}}$ - $\mathrm{arcmin}$ across an observation area of 670 square degrees. We measure the EE power spectrum over the angular multipole range $500\leqslant {\ell }\lt 3000$ , tracing the third to seventh acoustic peaks with high sensitivity. The statistical uncertainty on E-mode bandpowers is ∼2.3 $\mu {{\rm{K}}}^{2}$ at ${\ell }\sim 1000$ , with a systematic uncertainty of 0.5 $\mu {{\rm{K}}}^{2}$ . The data are consistent with the standard ΛCDM cosmological model with a probability-to-exceed of 0.38. We combine recent CMB E-mode measurements and make inferences about cosmological parameters in ΛCDM as well as in extensions to ΛCDM. Adding the ground-based CMB polarization measurements to the Planck data set reduces the uncertainty on the Hubble constant by a factor of 1.2 to ${H}_{0}=67\mathrm{.}20\pm 0\mathrm{.}57\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ . When allowing the number of relativistic species ( ${N}_{\mathrm{eff}}$ ) to vary, we find ${N}_{\mathrm{eff}}=2\mathrm{.}94\pm 0\mathrm{.}16$ , which is in good agreement with the standard value of 3.046. Instead allowing the primordial helium abundance ( ${Y}_{\mathrm{He}}$ ) to vary, the data favor ${Y}_{\mathrm{He}}=0\mathrm{.}248\pm 0\mathrm{.}012$ . This is very close to the expectation of 0.2467 from big bang nucleosynthesis. When varying both ${Y}_{\mathrm{He}}$ and ${N}_{\mathrm{eff}}$ , we find ${N}_{\mathrm{eff}}=2\mathrm{.}70\pm 0\mathrm{.}26$ and ${Y}_{\mathrm{He}}=0\mathrm{.}262\pm 0\mathrm{.}015$ .

Keywords: Cosmic microwave background radiation
Turbulence Spectra of Electron Density and Magnetic Field Fluctuations in the Local Interstellar Medium. We present the turbulence spectra of magnetic and electron density fluctuations in situ measured by Voyager 1 in the local interstellar medium from 2012 to 2019. The magnetic spectrum shows a Kolmogorov power law with a one-dimensional power-law index -5/3 at mk ≤ 10-8.8, where k is a wavenumber and m is the unit meter. A bulge of enhanced magnetic power is found at mk = 10-8.8-10-8.2. Meanwhile, the electron density spectrum also shows a Kolmogorov power law with a one-dimensional power-law index -5/3 in the inertial range. A bulge of enhanced power is found around the kinetic scales of mk ≈ 10-5-10-1. Based on the observational data, the relationships between the outer scale of the turbulent system and the powers of electron density and magnetic fluctuations are obtained. We then calculate the spectra locally for six individual time periods, within which the electron density and magnetic fluctuations are simultaneously observed. It is found that the power of perpendicular magnetic fluctuations is usually higher than that of parallel magnetic fluctuations, which indicates the dominance of Alfvén waves in turbulence spectrum. Part of the observed turbulence spectra reveal that the normalized parallel magnetic power exhibits a much higher intensity than the normalized electron density power in the local interstellar medium of low to moderate plasma beta (β = 0.1-0.8). This dominance in the parallel magnetic power cannot be explained by the linear magnetohydrodynamic modes alone and may be associated with the arc/spherically polarized Alfvén mode.

Keywords: Interstellar magnetic fields, Magnetohydrodynamics, Interplanetary turbulence, Interstellar medium
Exploring High-energy Emission from the BL Lacertae Object S5 0716+714 with the Fermi Large Area Telescope. We present the results of an extensive γ-ray data analysis of the emission from the blazar S5 0716+714 with the primary motivation to study its temporal and spectral variability behavior. In this work, we extract a 10 days binned γ-ray light curve from 2008 August 4 to 2016 April 27 in the energy range of 0.1-300 GeV and identify six outburst periods with peak flux of &gt;4 × 10-7 ph cm-2 s-1 from this highly variable source. The brightest flares are identified by zooming in these outburst periods to 1 day binning and using the Bayesian Blocks algorithm. The fastest variability timescale is found to be 1.5 ± 0.3 hr at MJD 57128.01 ± 0.01 with a peak flux above 100 MeV of (26.8 ± 6.9) × 10-7 ph cm-2 s-1. No hint of periodic modulations has been detected for the light curve of S5 0716+714. During the outburst phases, the γ-ray spectrum shows an obvious spectral break with a break energy between 0.93 and 6.90 GeV energies, which may be caused by an intrinsic break in the energy distribution of radiating particles. The five highest-energy photons, with E &gt; 100 GeV, imply that the high-energy emission from this source may originate from a moving emission region in a helical path upstream in the jet. The spectral behavior and temporal characteristics of the individual flares indicate that the location of the emission region lies in the sub-parsec scale (rγ &lt; 0.85 pc).

Keywords: Blazars, Relativistic jets, BL Lacertae objects
Tidal Disruptions of Main-sequence Stars. V. The Varieties of Disruptions. Tidal disruption events (TDEs) are generally imagined as the complete disruption of a star when it passes close to a supermassive black hole (SMBH). Relativistic apsidal precession is thought to quickly "circularize" the bound debris, forming a compact accretion disk, which then emits a flare of standardized light curve and spectrum. We show here that this picture holds in only a minority of cases. TDEs are more diverse and can be grouped into several categories distinguished by stellar pericenter distance rp; we estimate the relative frequency of these categories. Rapid circularization is rare both because it requires ${r}_{p}\leqslant {R}_{\mathrm{circ}}\sim 10{r}_{g}$ ( ${r}_{g}\equiv {{GM}}_{\mathrm{BH}}/{c}^{2}$ ) and because most events with ${r}_{p}\leqslant 14{r}_{g}$ lead to direct capture. For larger pericenter distances, ${R}_{\mathrm{circ}}\lt {r}_{p}\lt 27{r}_{g}$ (for MBH = 106 M⊙), main-sequence stars with M* ≲ 3 are completely disrupted, but the bound debris orbits are highly eccentric and possess semimajor axes ∼100× the scale of the expected compact disk. Partial disruptions with fractional mass loss ≳10% occur with a rate similar to that of total disruptions; for fractional mass loss ≳50%, the rate is ≈1/3 as large. Partial disruptions—which must precede total disruptions when the stars' angular momenta evolve in the "empty loss-cone" regime—change the orbital energy by factors ≳O(1). Partial disruption remnants are in general far from thermal equilibrium. Depending on its orbital energy and conditions within the stellar cluster surrounding the SMBH, a remnant may return after ∼O(100)-O(1000) yr and be fully disrupted, or it may rejoin the stellar cluster.

Keywords: Black hole physics, Supermassive black holes, Galactic center, Gravitation, Stellar dynamics, General relativity
Clustering of LRGs in the DECaLS DR8 Footprint: Distance Constraints from Baryon Acoustic Oscillations Using Photometric Redshifts. A photometric redshift sample of luminous red galaxies (LRGs) obtained from the DECam Legacy Survey (DECaLS) is analyzed to probe cosmic distances by exploiting the wedge approach of the two-point correlation function. Although the cosmological information is highly contaminated by the uncertainties existing in the photometric redshifts from the galaxy map, an angular diameter distance can be probed at the perpendicular configuration in which the measured correlation function is minimally contaminated. An ensemble of wedged correlation functions selected up to a given threshold based on having the least contamination was studied in previous work (Sridhar &amp; Song 2019) using simulations, and the extracted cosmological information was unbiased within this threshold. We apply the same methodology for analyzing the LRG sample from DECaLS, which will provide the optical imaging for targeting two-thirds of the Dark Energy Spectroscopic Instrument footprint and measure the angular diameter distances at z = 0.69 and z = 0.87 to be ${D}_{A}(0.697)=(1529\pm 73\,\mathrm{Mpc})({r}_{d}/{r}_{d,\mathrm{fid}})$ and ${D}_{A}(0.874)=(1674\pm 102\,\mathrm{Mpc})({r}_{d}/{r}_{d,\mathrm{fid}})$ with a fractional error of 4.77% and 6.09%, respectively. We obtain a value of H0 = 66.58 ± 5.31 km s-1 Mpc-1, which supports the H0 measured by all other baryon acoustic oscillation results and is consistent with the ΛCDM model.

Keywords: Cosmology, Large-scale structure of the universe, Distance measure, Photometry, High-redshift galaxies
On the X-Ray Properties of the Putative Central Compact Object in 1E 0102.2-7219. We have analyzed the archival Chandra X-ray Observatory observations of the compact feature in the Small Magellanic Cloud supernova remnant 1E 0102.2-7219, which has recently been suggested to be the central compact object remaining after the supernova explosion. In our analysis, we have used appropriate, time-dependent responses for each of the archival observations, have modeled the background instead of subtracting it, and have fit unbinned spectra to preserve the maximal spectral information. The spectrum of this feature is similar to the spectrum of the surrounding regions that have significantly enhanced abundances of O, Ne, and Mg. We find that the previously suggested blackbody model is inconsistent with the data, as Monte Carlo simulations indicate that more than 99% of the simulated data sets have a test statistic value lower than that of the data. The spectrum is described adequately by a nonequilibrium ionization thermal model with two classes of models that fit the data equally well. One class of models has a temperature of kT ∼ 0.79 keV, an ionization timescale of ∼3 × 1011 cm-3 s, and marginal evidence for enhanced abundances of O and Ne, and the other has a temperature of kT ∼ 0.91 keV, an ionization timescale of ∼7 × 1010 cm-3 s, and abundances consistent with local interstellar medium values. We also performed an image analysis and find that the spatial distribution of the counts is not consistent with that of a point source. The hypothesis of a point-source distribution can be rejected at the 99.9% confidence level. Therefore, this compact feature is most likely a knot of O- and Ne-rich ejecta associated with the reverse shock.

Keywords: Supernova remnants, X-ray sources, Interstellar medium
Structure and Rotation of Young Massive Star Clusters in a Simulated Dwarf Starburst. We analyze the three-dimensional shapes and kinematics of the young star cluster population forming in a high-resolution GRIFFIN project simulation of a metal-poor dwarf galaxy starburst. The star clusters, which follow a power-law mass distribution, form from the cold phase interstellar medium with an initial mass function sampled with individual stars down to four solar masses at sub-parsec spatial resolution. Massive stars and their important feedback mechanisms are modeled in detail. The simulated clusters follow a surprisingly tight relation between the specific angular momentum and mass with indications of two sub-populations. Massive clusters (Mcl ≳ 3 × 104 M⊙) have the highest specific angular momenta at low ellipticities (ɛ ∼ 0.2) and show alignment between their shapes and rotation. Lower mass clusters have lower specific angular momenta with larger scatter, show a broader range of elongations, and are typically misaligned indicating that they are not shaped by rotation. The most massive clusters (M ≳ 105 M⊙) accrete gas and protoclusters from a ≲100 pc scale local galactic environment on a t ≲ 10 Myr timescale, inheriting the ambient angular momentum properties. Their two-dimensional kinematic maps show ordered rotation at formation, up to v ∼ 8.5 km s-1, consistent with observed young massive clusters and old globular clusters, which they might evolve into. The massive clusters have angular momentum parameters λR ≲ 0.5 and show Gauss-Hermite coefficients h3 that are anti-correlated with the velocity, indicating asymmetric line-of-sight velocity distributions as a signature of a dissipative formation process.

Keywords: Stellar kinematics, Computational astronomy, Young star clusters, Star formation
The Mode Switching in Pulsar J1326-6700. We report on a detailed study of the mode switching in pulsar J1326-6700 by analyzing the data acquired from the Parkes 64 m radio telescope at 1369 MHz. During the abnormal mode, the emission at the central and trailing components becomes extremely weak. Meanwhile, the leading emission shifts toward earlier longitude by almost 2°, and remains in this position for typically less than a minute. The mean flux density of the normal mode is almost five times that of the abnormal mode. Our data show that, for PSR J1326-6700, 85% of the time was spent in the normal mode and 15% was in the abnormal mode. The intrinsic distributions of mode timescales can be well described by Weibull distributions, which present a certain amount of memory in mode switching. Furthermore, a quasiperiodicity has been identified in the mode switching in pulsar J1326-6700. The estimated delay emission heights based on the kinematical effects indicate that the abnormal mode may have originated from higher altitude than the normal mode.

Keywords: Pulsars
Measuring Stellar and Black Hole Masses of Tidal Disruption Events. The flare produced when a star is tidally disrupted by a supermassive black hole holds potential as a diagnostic of both the black hole mass and the star mass. We propose a new method to realize this potential based upon a physical model of optical/UV light production in which shocks near the apocenters of debris orbits dissipate orbital energy, which is then radiated from that region. Measurement of the optical/UV luminosity and color temperature at the peak of the flare leads directly to the two masses. The black hole mass depends mostly on the temperature observed at peak luminosity, while the mass of the disrupted star depends mostly on the peak luminosity. We introduce TDEMASS, a method to infer the black hole and stellar masses given these two input quantities. Using TDEMASS, we find, for 21 well-measured events, black hole masses between 5 × 105 and 107 M⊙ and disrupted stars with initial masses between 0.6 and 13 M⊙. An open-source PYTHON-based tool for TDEMASS is available at https://github.com/taehoryu/TDEmass.git.

Keywords: Black hole physics, Supermassive black holes, Gravitation, Tidal disruption, Galaxy nuclei, Stellar physics