adsabs/SciX_UAT_keywords huggingface dataset:
Introducing a New Spitzer Master BLISS Map to Remove the Instrument Systematic Phase-curve-parameter Degeneracy, as Demonstrated by a Reanalysis of the 4.5 μm WASP-43b Phase Curve

While Spitzer Infrared Array Camera (IRAC) systematics are generally well understood, each data set can provide its own challenges that continue to teach us about the underlying functional form of these systematics. Multiple groups have analyzed the phase curves of WASP-43b with varying detrending techniques, each obtaining different results. In this work, we take another look at WASP-43b while exploring the degenerate relation between Bilinearly Interpolated Subpixel Sensitivity (BLISS) mapping, point response function (PRF)-FWHM detrending, and phase curve parameters. We find that there is a strong correlation between the detrending parameters in the two models, and best-fit phase curve amplitudes vary strongly when the data are temporally binned. To remove this degeneracy, we present a new Gaussian centroided intrapixel sensitivity map (hereafter fixed sensitivity map), generated using 3,712,830 exposures spanning 5 yr, for a variety of aperture sizes at 4.5 μm. We find evidence for time variability in the sensitivity at 3.6 μm and do not generate a visit-independent map for this channel. With the fixed 4.5 μm intrapixel sensitivity map, the best fits for WASP-43b no longer vary strongly with bin size and PRF-FWHM detrending is no longer required to remove correlated noise. For data sets that do not fall completely within the sweet spot, temporal binning should not be used in the analysis of Spitzer phase curves. We confirm nightside emission for WASP-43b with a disk-integrated nightside temperature of 806 ± 48 K at 4.5 μm. The 4.5 μm maps are available at github.com/kevin218/POET.

Keywords: exoplanet astronomy; hot jupiters; exoplanet atmospheres
Stumbling over Planetary Building Blocks: AU Microscopii as an Example of the Challenge of Retrieving Debris-disk Dust Properties

We explore whether assumptions about dust grain shape affect the resulting estimates of the composition and grain size distribution of the AU Microscopii (AU Mic) debris disk from scattered-light data collected by Lomax et al. The near edge-on orientation of the AU Mic debris disk makes it ideal for studying the effect of the scattering phase function on the measured flux ratios as a function of wavelength and projected distance. Previous efforts to model the AU Mic debris disk have invoked a variety of dust grain compositions and explored the effect of porosity, but did not undertake a systematic effort to explore a full range of size distributions and compositions to understand possible degeneracies in fitting the data. The degree to which modeling dust grains with more realistic shapes compounds these degeneracies has also not previously been explored. We find differences in the grain properties retrieved depending on the grain shape model used. We also present here our calculations of porous grains of size parameters x = 0.1 to 48 and complex refractive indices (m = n + iκ) ranging from n = 1.1 to 2.43 and k = 0 to 1.0, covering multiple compositions at visible and near-infrared wavelengths such as ice, silicates, amorphous carbon, and tholins.

Keywords: circumstellar dust; circumstellar disks; interplanetary dust; debris disks
Patchy Kinetic Sunyaev-Zel'dovich Effect with Controlled Reionization History and Morphology

Using the novel semi-numerical code for reionization AMBER, we model the patchy kinetic Sunyaev-Zel'dovich (kSZ) effect by directly specifying the reionization history with the redshift midpoint z mid, duration Δz, and asymmetry A z. We further control the ionizing sources and radiation through the minimum halo mass M h and the radiation mean free path λ mfp. AMBER reproduces the free-electron number density and the patchy kSZ power spectrum of radiation-hydrodynamic simulations at the target resolution (1 Mpc h -1) with matched reionization parameters. With a suite of (2 Gpc/h)3 simulations using AMBER, we first constrain the redshift midpoint 6.0 < z mid < 8.9 using the Planck 2018 Thomson optical depth result (95% CL). Then, assuming z mid = 8, we find that the amplitude of ${D}_{{\ell }=3000}^{\mathrm{pkSZ}}$ scales linearly with the duration of reionization Δ z and is consistent with the 1σ upper limit from South Pole Telescope (SPT) results up to Δ z < 5.1 (Δ z encloses 5%-95% ionization). Moreover, a shorter λ mfp can lead to a ~10% lower ${D}_{{\ell }=3000}^{\mathrm{pkSZ}}$ and a flatter slope in the ${D}_{{\ell }=3000}^{\mathrm{pkSZ}}-{{\rm{\Delta }}}_{z}$ scaling relation, thereby affecting the constraints on Δ z at ℓ = 3000. Allowing z mid and λ mfp to vary simultaneously, we get spectra consistent with the SPT result (95% CL) up to Δ z = 12.8 (but A z > 8 is needed to ensure the end of reionization before z = 5.5). We show that constraints on the asymmetry require ~0.1 μ k 2 measurement accuracy at multipoles other than ℓ = 3000. Finally, we find that the amplitude and shape of the kSZ spectrum are only weakly sensitive to M h under a fixed reionization history and radiation mean free path.

Keywords: cosmic microwave background radiation; sunyaev-zeldovich effect; reionization; cosmology
Are There Larger Stellar Velocity Dispersions in Low-redshift Type 1 AGNs than in Type 2 AGNs?

The main objective of this article is to check the Unified Model (UM) for the expected similar stellar velocity dispersions between Type 1 and Type 2 active galactic nuclei (AGNs) and then to provide further clues on black hole (BH) mass properties. Unlike previous comparisons of BH masses estimated from M BH-σ relations for Type 2 AGNs and from virial BH masses for Type 1 AGNs, reliable stellar velocity dispersions σ measured from absorption features around 4000 Å are directly compared between the thus far largest samples of 6260 low-redshift (z < 0.3) Type 1 AGNs and almost all Type 2 AGNs in SDSS DR12. Although half of Type 1 AGNs do not have a measured σ due to unapparent absorption features overwhelmed by AGN activities, both properties of the mean spectra of Type 1 AGNs with and without a measured σ and a positive dependence of σ on the [O III] luminosity can lead to a statistically larger σ for all Type 1 AGNs compared to the 6260 Type 1 AGNs with measured stellar velocity dispersions. Then, direct σ comparisons can lead to a statistically larger σ in Type 1 AGNs, with a confidence level higher than 10σ, after considering the necessary effects of different redshifts and different central AGN activities. Although Type 1 AGNs have a σ of only about (9 ± 3)% larger than Type 2 AGNs, the difference cannot be well explained at the current stage. Unless there is strong evidence to support different M BH-σ relations or to support quite different evolutionary histories between Type 1 and Type 2 AGNs, the statistically larger σ in Type 1 AGNs provides a strong challenge to the UM of AGNs.

Keywords: active galaxies; active galactic nuclei; supermassive black holes; emission line galaxies
An ALMA Gas-dynamical Mass Measurement of the Supermassive Black Hole in the Local Compact Galaxy UGC 2698

We present 0"14 resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations of the circumnuclear gas disk in UGC 2698, a local compact galaxy. The disk exhibits regular rotation with projected velocities rising to 450 km s-1 near the galaxy center. We fit gas-dynamical models to the ALMA data cube, assuming the CO emission originates from a dynamically cold, thin disk, and measured the mass of the supermassive black hole (BH) in UGC 2698 to be MBH = (2.46 ± 0.07 [1σ statistical] ${}_{-0.78}^{+0.70}$ [systematic]) × 109 M⊙. UGC 2698 is part of a sample of nearby early-type galaxies that are plausible z ~ 2 red nugget relics. Previous stellar-dynamical modeling for three galaxies in the sample found BH masses consistent with the BH mass-stellar velocity dispersion (MBH - σ⋆) relation but over-massive relative to the BH mass-bulge luminosity (MBH - Lbul) correlation, suggesting that BHs may gain the majority of their mass before their host galaxies. However, UGC 2698 is consistent with both MBH - σ⋆ and MBH - Lbul. As UGC 2698 has the largest stellar mass and effective radius in the local compact galaxy sample, it may have undergone more recent mergers that brought it in line with the BH scaling relations. Alternatively, given that the three previously measured compact galaxies are outliers from MBH - Lbul, while UGC 2698 is not, there may be significant scatter at the poorly sampled high-mass end of the relation. Additional gas-dynamical MBH measurements for the compact galaxy sample will improve our understanding of BH-galaxy co-evolution.

Keywords: supermassive black holes; molecular gas; millimeter astronomy; submillimeter astronomy; galaxy kinematics; astronomy data modeling; early-type galaxies
Rapidly Evolving Transients from the Hyper Suprime-Cam SSP Transient Survey

Rapidly evolving transients form a new class of transients that show shorter timescales of light curves than those of typical core-collapse and thermonuclear supernovae. We performed a systematic search for rapidly evolving transients using deep data taken with the Hyper Suprime-Cam Subaru Strategic Program Transient Survey. By measuring the timescales of the light curves of 1824 transients, we identified five rapidly evolving transients. Our samples are found in a wide range of redshifts (0.3 ≤ z ≤ 1.5) and peak absolute magnitudes (-17 ≥ MI ≥ -20). The light-curve properties are similar to those of the previously discovered rapidly evolving transients. They show a relatively blue spectral energy distribution, with the best-fit blackbody of 8000-18,000 K. We show that some of the transients require power sources other than the radioactive decays of 56Ni because of their high peak luminosities and short timescales. The host galaxies of all of the samples are star-forming galaxies, suggesting a massive star origin for the rapidly evolving transients. The event rate is roughly estimated to be ∼4000 events yr-1 Gpc-3, which is about 1% of core-collapse supernovae.

Keywords: supernovae
Near-infrared Census of RR Lyrae Variables in the Messier 3 Globular Cluster and the Period-Luminosity Relations

We present new near-infrared (NIR), JHKs, time-series observations of RR Lyrae variables in the Messier 3 (NGC 5272) globular cluster using the WIRCam instrument at the 3.6 m Canada-France-Hawaii Telescope. Our observations cover a sky area of ∼21' × 21' around the cluster center and provide an average of 20 epochs of homogeneous JHKs-band photometry. New homogeneous photometry is used to estimate robust mean magnitudes for 175 fundamental-mode (RRab), 47 overtone-mode (RRc), and 11 mixed-mode (RRd) variables. Our sample of 233 RR Lyrae variables is the largest thus far obtained in a single cluster with time-resolved, multiband NIR photometry. NIR-to-optical amplitude ratios for RR Lyrae in Messier 3 exhibit a systematic increase moving from RRc to short-period (P < 0.6 day) and long-period (P ≳ 0.6 day) RRab variables. We derive JHKs-band period-luminosity relations for RRab, RRc, and the combined sample of variables. Absolute calibrations based on the theoretically predicted period-luminosity-metallicity relations for RR Lyrae stars yield a distance modulus, $\mu =15.041\pm 0.017\,(\mathrm{statistical})\pm 0.036\,(\mathrm{systematic})$ mag, to Messier 3. When anchored to trigonometric parallaxes for nearby RR Lyrae stars from the Hubble Space Telescope and the Gaia mission, our distance estimates are consistent with those resulting from the theoretical calibrations, albeit with relatively larger systematic uncertainties.

Keywords: rr lyrae variable stars; stellar pulsations; globular star clusters; distance indicators; distance measure
Resolving the Bow Shock and Tail of the Cannonball Pulsar PSR J0002+6216

We present X-ray and radio observations of the recently discovered bow-shock pulsar wind nebula (PWN) associated with PSR J0002+6216, characterizing the PWN morphology, which was unresolved in previous studies. The multifrequency, multiepoch Very Large Array (VLA) radio observations reveal a cometary tail trailing the pulsar and extending up to 5.'3, with multiple kinks along the emission. The presented radio continuum images from multiconfiguration broadband VLA observations are one of the first results from the application of multiterm multifrequency synthesis deconvolution in combination with the AWProject gridder implemented in the Common Astronomy Software Applications (CASA) package. The X-ray emission observed with Chandra extends to only 21″, fades quickly, and has some hot spots present along the extended radio emission. These kinks could indicate the presence of density variations in the local interstellar medium or turbulence. The bow-shock standoff distance estimates a small bow-shock region with a size of 0.003-0.009 pc, consistent with the pulsar spin-down power of $\dot{E}$ = 1.51 × 1035 erg s-1 estimated from timing. The high-resolution radio image reveals the presence of an asymmetry in the bow-shock region, which is also present in the X-ray image. The broadband radio image shows an unusually steep spectrum along with a flat-spectrum sheath, which could indicate varying opacity or energy injection into the region. Spatially resolved X-ray spectra provide marginal evidence of synchrotron cooling along the extended tail. Our analysis of the X-ray data also shows that this pulsar has a low spin-down power and one of the lowest X-ray efficiencies observed in these objects.

Keywords: pulsar wind nebulae; pulsars; neutron stars; x-ray sources
An Infrared View of the Obscured AGN Environment in NGC 4945

NGC 4945 harbors one of the nearest active galactic nuclei (AGNs), which allows us to reach high spatial resolution with current observational facilities. The Seyfert 2 nucleus is deeply obscured by an edge-on disk with A V ~ 14, requiring infrared observations to study circumnuclear structures and the interstellar medium. In this work, we present an imaging and long-slit spectroscopic study of the nuclear region with a spatial resolution of 6.5 pc, based on Flamingos-2 (F2) and T-ReCS data taken at the Gemini South observatory. We report subarcsecond photometric measurements of the nucleus in J, H, and K s filters, and at larger apertures. We do not detect nuclear variability. The nuclear spectra confirm that even in the K band the AGN emission-line features are completely obscured by dust. We detect a circumnuclear disk in the K band as well as in the mid-infrared N and Q abands, with a radial scale length of ~120 pc. The disk shows knots mostly in a ring-like arrangement that has been previously detected with Paα observations from the Hubble Space Telescope, indicating that these are deeply embedded, massive young star clusters. We present here the spectrum of one of the brightest unresolved objects (R < 5 pc), which we identify as a super star cluster candidate with ${M}_{{K}_{{\rm{s}}}}\,-16.6\pm 0.4$ . For the circumnuclear region, a detailed rotation curve allows us to measure a nuclear mass of M = (4.4 ± 3) × 106 M ⊙ within a radius of ~6.5 pc. We also report the detection of hot dust (~1000 K) out to a nuclear distance of 80 pc measured along the semimajor axis.

Keywords: active galactic nuclei; supermassive black holes; near infrared astronomy; galaxy nuclei
Detailed Abundances in the Galactic Center: Evidence of a Metal-rich Alpha-enhanced Stellar Population

We present a detailed study of the composition of 20 M giants in the Galactic center with 15 of them confirmed to be in the nuclear star cluster. As a control sample we have also observed 7 M giants in the Milky Way disk with similar stellar parameters. All 27 stars are observed using the NIRSPEC spectrograph on the KECK II telescope in the K-band at a resolving power of R = 23,000. We report the first silicon abundance trends versus [Fe/H] for stars in the Galactic center. While finding a disk/bulge-like trend at subsolar metallicities, we find that [Si/Fe] is enhanced at supersolar metallicities. We speculate on possible enrichment scenarios to explain such a trend. However, the sample size is modest and the result needs to be confirmed by additional measurements of silicon and other α-elements. We also derive a new distribution of [Fe/H] and find the most metal-rich stars at [Fe/H] = +0.5 dex, confirming our earlier conclusions that the Galactic center hosts no stars with extreme chemical compositions.

Keywords: chemical abundances; late-type stars; star clusters; galactic center; galaxy chemical evolution; chemical enrichment
Flux Calibration of CHIME/FRB Intensity Data

Fast radio bursts (FRBs) are bright radio transients of microsecond to millisecond duration and unknown extragalactic origin. Central to the mystery of FRBs are their extremely high characteristic energies, which surpass the typical energies of other radio transients of similar duration, like Galactic pulsar and magnetar bursts, by orders of magnitude. Calibration of FRB-detecting telescopes for burst flux and fluence determination is crucial for FRB science, as these measurements enable studies of the FRB energy and brightness distribution in comparison to progenitor theories. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio interferometer of cylindrical design. This design leads to a high FRB detection rate but also leads to challenges for CHIME/FRB flux calibration. This paper presents a comprehensive review of these challenges, as well as the automated flux calibration software pipeline that was developed to calibrate bursts detected in the first CHIME/FRB catalog, consisting of 536 events detected between 2018 July 25 and 2019 July 1. We emphasize that, due to limitations in the localization of CHIME/FRB bursts, flux and fluence measurements produced by this pipeline are best interpreted as lower limits, with uncertainties on the limiting value.

Keywords: radio transient sources; flux calibration; calibration; radio astronomy
Cosmological Evolution of Flat-spectrum Radio Quasars Based on the Swift/BAT 105 Month Catalog and Their Contribution to the Cosmic MeV Gamma-Ray Background Radiation

We present a new X-ray luminosity function of flat-spectrum radio quasars (FSRQs) utilizing the latest Swift/BAT 105 month X-ray source catalog. Contrary to previous studies of FSRQs in the X-ray band, using the luminosity-dependent density evolution model we find that FSRQs show evolutionary peaks at z ∼ 1-2 depending on luminosities. Our result is rather consistent with the evolution of FSRQs seen in the radio and GeV bands, although the number density is a factor of 5-10 smaller. We further explore the contribution of FSRQs to the cosmic MeV gamma-ray background radiation. We find that FSRQs can explain only ∼3% of the observed MeV gamma-ray background fluxes around 1 MeV, indicating other populations are required. Future MeV gamma-ray observations will be keys for understanding the origin of the MeV gamma-ray background radiation.

Keywords: relativistic jets; galaxy jets
Evolution of a Peculiar Type Ibn Supernova SN 2019wep

We present a high-cadence short term photometric and spectroscopic monitoring campaign of a type Ibn SN 2019wep, which is one of the rare SN Ibn after SNe 2010al and 2019uo to display signatures of flash ionization (He II, C III, N III). We compare the decline rates and rise time of SN 2019wep with other SNe Ibn and fast transients. The post-peak decline in all bands (0.1 mag day-1) are consistent with SNe Ibn but less than the fast transients. On the other hand, the Δm 15 values are slightly lower than the average values for SNe Ibn but consistent with the fast transients. The rise time is typically shorter than SNe Ibn but longer than fast transients. SN 2019wep lies at the fainter end of SNe Ibn but possesses an average luminosity among the fast transients sample. The peculiar color evolution places it between SNe Ib and the most extreme SNe Ibn. The bolometric light-curve modeling shows resemblance with SN 2019uo with ejecta masses consistent with SNe Ib. SN 2019wep belongs to the P cygni subclass of SNe Ibn and shows faster evolution in line velocities as compared to the emission subclass. The post-maximum spectra show close resemblance with ASASSN-15ed hinting it to be of SN Ib nature. The low He I CSM velocities and residual Hα further justifies it and provide evidence of an intermittent progenitor between Wolf-Rayet and LBV stars.

Keywords: supernovae; supernova dynamics; core-collapse supernovae; ccd photometry; spectroscopy
Clustering Behavior in Solar Flare Dynamics

The solar magnetic activity cycle provides energy input that is released in intense bursts of radiation known as solar flares. As such, the dynamics of the activity cycle is embedded in the sequence of times between the flare events. Recent analysis shows that solar flares exhibit memory on different timescales. These previous studies showed that the time ordering of flare events is not random, but rather there is dependence between successive flares. In the present work, the clustering of flares is demonstrated through a straightforward nonparametric method where the cumulative distribution function of successive flares is compared with the cumulative distribution function of surrogate sequences of flares obtained by random permutation of flares. The random permutation is performed within rate-variable Bayesian blocks during which the flare rate is assumed to be constant. Differences between the cumulative distribution functions are substantial on a timescale around 3 hr, suggesting that flare recurrence on that timescale is more likely than would be expected if the waiting time were drawn from a nonstationary Poisson process.

Keywords: solar flares
JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B

We present 1-5 μm spectroscopy of the young planetary mass companion TWA 27B (2M1207B) performed with NIRSpec on board the James Webb Space Telescope. In these data, the fundamental band of CH4 is absent, and the fundamental band of CO is weak. The nondetection of CH4 reinforces a previously observed trend of weaker CH4 with younger ages among L dwarfs, which has been attributed to enhanced nonequilibrium chemistry among young objects. The weakness of CO may reflect an additional atmospheric property that varies with age, such as the temperature gradient or cloud thickness. We are able to reproduce the broad shape of the spectrum with an ATMO cloudless model that has T eff = 1300 K, nonequilibrium chemistry, and a temperature gradient reduction caused by fingering convection. However, the fundamental bands of CH4 and CO are somewhat stronger in the model. In addition, the model temperature of 1300 K is higher than expected from evolutionary models given the luminosity and age of TWA 27B (T eff = 1200 K). Previous models of young L-type objects suggest that the inclusion of clouds could potentially resolve these issues; it remains to be seen whether cloudy models can provide a good fit to the 1-5 μm data from NIRSpec. TWA 27B exhibits emission in Paschen transitions and the He I triplet at 1.083 μm, which are signatures of accretion that provide the first evidence of a circumstellar disk. We have used the NIRSpec data to estimate the bolometric luminosity of TWA 27B (log L/L ⊙ = -4.466 ± 0.014), which implies a mass of 5-6 M Jup according to evolutionary models. *Based on observations made with the NASA/ESA/CSA James Webb Space Telescope, the Gaia mission, the Two Micron All Sky Survey, and the Wide-field Infrared Survey Explorer

Keywords: brown dwarfs; l dwarfs; exoplanet atmospheres; circumstellar disks; protoplanetary disks; substellar companion stars