adsabs/SciX_UAT_keywords huggingface dataset:
Probing Planets with Exomoons: The Cases of Kepler-1708 b and Kepler-1625 b

The tidal interactions between a planet and moon can provide insight into the properties of the host planet. The recent exomoon candidates Kepler-1708 b-i and Kepler-1625 b-i are Neptune-sized satellites orbiting Jupiter-like planets and provide an opportunity to apply such methods. We show that if the tidal migration time is roughly equal to the age of these systems, then the tidal dissipation factor Q for the planets Kepler-1708 b and Kepler-1625 b have values of ~3 × 105-3 × 106 and ~1.5 × 105-4 × 105, respectively. In each case, these are consistent with estimates for gas-giant planets. Even though some work suggests an especially large semimajor axis for Kepler-1625 b-i, we find that this would imply a surprisingly low Q ~ 2000 for a gas giant unless the moon formed at essentially its current position. More detailed predictions for the moons' initial semimajor axis could provide even better constraints on Q, and we discuss the formation scenarios for a moon in this context. Similar arguments can be used as more exomoons are discovered in the future to constrain exoplanet interior properties. This could be especially useful for exoplanets near the sub-Neptune/super-Earth radius gap where the planet structure is uncertain.

Keywords: exoplanet dynamics; exoplanet tides; natural satellites (extrasolar)
Lopsided Galaxy Distributions in Massive TNG300 Clusters

Studies of isolated central galaxies and their satellites have shown that the spatial distributions of the satellites are distinctly "lopsided" with respect to the locations of the central galaxies. Here we extend this type of analysis to larger systems by analyzing the lopsidedness of 280 massive galaxy clusters in the IllustrisTNG300 Λ Cold Dark Matter simulation. Using a pairwise clustering statistic, we compute the probability that pairs of cluster galaxies are separated by a given polar angle difference, Δϕ, in the plane of the sky. Relative to the location of the central cluster galaxy, we find a statistically significant excess of galaxy pairs that are located on the same side of the cluster. The lopsidedness of the galaxy distribution is most pronounced for large clusters and for pairs of intrinsically red galaxies. The results summarized here were presented at the 243rd meeting of the American Astronomical Society.

Keywords: cosmology; galaxy clusters; cold dark matter
Multi-scale Physical Properties of NGC 6334 as Revealed by Local Relative Orientations between Magnetic Fields, Density Gradients, Velocity Gradients, and Gravity

We present ALMA dust polarization and molecular line observations toward four clumps (I(N), I, IV, and V) in the massive star-forming region NGC 6334. In conjunction with large-scale dust polarization and molecular line data from JCMT, Planck, and NANTEN2, we make a synergistic analysis of relative orientations between magnetic fields (θ B), column density gradients (θ NG), local gravity (θ LG), and velocity gradients (θ VG) to investigate the multi-scale (from ~30 to 0.003 pc) physical properties in NGC 6334. We find that the relative orientation between θ B and θ NG changes from statistically more perpendicular to parallel as column density ( ${N}_{{{\rm{H}}}_{2}}$ ) increases, which is a signature of trans-to-sub-Alfvénic turbulence at complex/cloud scales as revealed by previous numerical studies. Because θ NG and θ LG are preferentially aligned within the NGC 6334 cloud, we suggest that the more parallel alignment between θ B and θ NG at higher ${N}_{{{\rm{H}}}_{2}}$ is because the magnetic field line is dragged by gravity. At even higher ${N}_{{{\rm{H}}}_{2}}$ , the angle between θ B and θ NG or θ LG transits back to having no preferred orientation, or statistically slightly more perpendicular, suggesting that the magnetic field structure is impacted by star formation activities. A statistically more perpendicular alignment is found between θ B and θ VG throughout our studied ${N}_{{{\rm{H}}}_{2}}$ range, which indicates a trans-to-sub-Alfvénic state at small scales as well, and this signifies that magnetic field has an important role in the star formation process in NGC 6334. The normalized mass-to-flux ratio derived from the polarization-intensity gradient (KTH) method increases with ${N}_{{{\rm{H}}}_{2}}$ , but the KTH method may fail at high ${N}_{{{\rm{H}}}_{2}}$ due to the impact of star formation feedback.

Keywords: polarimetry; magnetic fields; star formation; molecular clouds; interstellar medium
X-Ray Luminosity of Decades-old Supernovae

The transition from supernovae (SNe) to supernova remnants (SNRs) remains poorly understood, given the age gap between well-studied examples of the two. In order to bridge this gap, we analyzed archival Chandra data for some of the oldest supernovae detected in X-rays, in order to extend their light curves out to late times. We fitted the spectra with thermal models. All the SNe with multiple X-ray data points were found to have similar X-ray luminosity, which was decreasing with time. The X-ray luminosity will likely continue to decrease while the SNe are evolving in a wind medium, but is anticipated to increase in the Sedov phase when the SNe are interacting with a constant density interstellar medium, bringing it in line with observed SNRs

Keywords: supernovae; type ii supernovae; x-ray sources; light curves; supernova remnants
Pre-impact Thermophysical Properties and the Yarkovsky Effect of NASA DART Target (65803) Didymos

The NASA Double Asteroid Redirection Test (DART) spacecraft impacted the secondary body of the binary asteroid (65803) Didymos on 2022 September 26 and altered its orbit about the primary body. Before the DART impact, we performed visible and mid-infrared observations to constrain the pre-impact thermophysical properties of the Didymos system and to model its Yarkovsky effect. Analysis of the photometric phase curve derives a Bond albedo of 0.07 ± 0.01, and a thermophysical analysis of the mid-infrared observations derives a thermal inertia of 320 ± 70 J m‑2 K‑1 s‑1/2 and a thermal roughness of 40° ± 3° rms slope. These properties are compatible with the ranges derived for other S-type near-Earth asteroids. Model-to-measurement comparisons of the Yarkovsky orbital drift for Didymos derives a bulk density of 2750 ± 350 kg m‑3, which agrees with other independent measures based on the binary mutual orbit. This bulk density indicates that Didymos is spinning at or near its critical spin-limit at which self-gravity balances equatorial centrifugal forces. Furthermore, comparisons with the post-impact infrared observations presented in Rivkin et al. indicate no change in the thermal inertia of the Didymos system following the DART impact. Finally, orbital temperature simulations indicate that subsurface water ice is stable over geologic timescales in the polar regions if present. These findings will be investigated in more detail by the upcoming ESA Hera mission.

Keywords: asteroids; near-earth objects; asteroid dynamics; asteroid surfaces; infrared astronomy
Constraining Galaxy Halos from the Dispersion and Scattering of Fast Radio Bursts and Pulsars

Fast radio bursts (FRBs) can be scattered by ionized gas in their local environments, host galaxies, intervening galaxies along their lines of sight (LOS), the intergalactic medium, and the Milky Way. The relative contributions of these different media depend on their geometric configuration and the internal properties of the gas. When these relative contributions are well understood, FRB scattering is a powerful probe of density fluctuations along the LOS. The precise scattering measurements for FRB 121102 and FRB 180916 allow us to place an upper limit on the amount of scattering contributed by the Milky Way halo to these FRBs. The scattering time $\tau \propto (\widetilde{F}\times {\mathrm{DM}}^{2}){A}_{\tau }$ , where DM is the dispersion measure, $\widetilde{F}$ quantifies electron density variations with $\widetilde{F}=0$ for a smooth medium, and the dimensionless constant Aτ quantifies the difference between the mean scattering delay and the 1/e scattering time typically measured. A likelihood analysis of the observed scattering and halo DM constraints finds that $\widetilde{F}$ is at least an order of magnitude smaller in the halo than in the Galactic disk. The maximum pulse broadening from the halo is τ ≲ 12 μs at 1 GHz. We compare our analysis of the Milky Way halo with other galaxy halos by placing limits on the scattering contributions from halos intersecting the LOS to FRB 181112 and FRB 191108. Our results are consistent with halos making negligible or very small contributions to the scattering times of these FRBs.

Keywords: milky way stellar halo; galaxy stellar halos; circumgalactic medium; radio transient sources; interstellar medium
Multi-messenger Approaches to Supermassive Black Hole Binary Detection and Parameter Estimation: Implications for Nanohertz Gravitational Wave Searches with Pulsar Timing Arrays

Pulsar timing array (PTA) experiments are becoming increasingly sensitive to gravitational waves (GWs) in the nanohertz frequency range, where the main astrophysical sources are supermassive black hole binaries (SMBHBs), which are expected to form following galaxy mergers. Some of these individual SMBHBs may power active galactic nuclei, and thus their binary parameters could be obtained electromagnetically, which makes it possible to apply electromagnetic (EM) information to aid the search for a GW signal in PTA data. In this work, we investigate the effects of such an EM-informed search on binary detection and parameter estimation by performing mock data analyses on simulated PTA data sets. We find that by applying EM priors, the Bayes factor of some injected signals with originally marginal or sub-threshold detectability (i.e., Bayes factor ~1) can increase by a factor of a few to an order of magnitude, and thus an EM-informed targeted search is able to find hints of a signal when an uninformed search fails to find any. Additionally, by combining EM and GW data, one can achieve an overall improvement in parameter estimation, regardless of the source's sky location or GW frequency. We discuss the implications for the multi-messenger studies of SMBHBs with PTAs.

Keywords: gravitational waves; supermassive black holes; active galaxies
Two-component Jets of GRB 160623A as Shocked Jet Cocoon Afterglow

Two components of jets associated with the afterglow of the gamma-ray burst (GRB) 160623A were observed with multifrequency observations including long-term monitoring in a submillimeter range (230 GHz) using the Submillimeter Array. The observed light curves with temporal breaks suggest on the basis of the standard forward-shock synchrotron-radiation model that the X-ray radiation is narrowly collimated with an opening angle θ_{n,j}<∼ 6°, whereas the radio radiation originated from wider jets (∼27°). The temporal and spectral evolutions of the radio afterglow agree with those expected from a synchrotron-radiation modeling with typical physical parameters, except for the fact that the observed wide jet opening angle for the radio emission is significantly larger than the theoretical maximum opening angle. By contrast, the opening angle of the X-ray afterglow is consistent with the typical value of GRB jets. Since the theory of the relativistic cocoon afterglow emission is similar to that of a regular afterglow with an opening angle of ∼30°, the observed radio emission can be interpreted as the shocked jet cocoon emission. This result therefore indicates that the two components of the jets observed in the GRB 160623A afterglow are caused by the jet and the shocked jet cocoon afterglows.

Keywords: gamma-ray bursts; gamma-ray astronomy; submillimeter astronomy; relativistic jets
Projected Cosmological Constraints from Strongly Lensed Supernovae with the Roman Space Telescope

One of the primary mission objectives of the Roman Space Telescope is to investigate the nature of dark energy with a variety of methods. Observations of Type I supernovae (SNe Ia) will be one of the principal anchors of the Roman cosmology program through traditional luminosity distance measurements. This SNe Ia cosmology program can provide another valuable cosmological probe, without altering the strategy of the mission: time delay cosmography with gravitationally lensed supernova (SN). In this work, we forecast lensed SN cosmology constraints with the Roman Space Telescope, while providing useful tools for future work. Using the anticipated characteristics of the Roman SNe Ia survey, we have constructed mock catalogs of expected resolved lensing systems, as well as strongly lensed Type Ia and core-collapse (CC) SN light curves, including microlensing effects. We predict Roman will find ∼11 lensed SNe Ia and ∼20 CCSNe, depending on the survey strategy. Next, we estimate the time delay precision obtainable with Roman (Ia: ∼2 days, CC: ∼3 days), and use a Fisher matrix analysis to derive projected constraints on H0,Ωm, and the dark energy equation of state, w, for each SNe Ia survey strategy. A strategy optimized for the discovery of high-redshift SNe Ia is preferred when considering the constraints possible from both SNe Ia and lensed SN cosmology, also delivering ∼1.5 times more lensed SNe than other proposed survey strategies.

Keywords: supernovae; strong gravitational lensing; gravitational microlensing; cosmology
Limits on Hierarchical Black Hole Mergers from the Most Negative χ eff Systems

It has been proposed that some black holes (BHs) in binary black hole (BBH) systems are born from "hierarchical mergers" (HMs), i.e., earlier mergers of smaller BHs. These HM products have spin magnitudes χ ~ 0.7, and, if they are dynamically assembled into BBH systems, their spin orientations will sometimes be antialigned with the binary orbital angular momentum. In fact, as Baibhav et al. showed, ~16% of BBH systems that include HM products will have an effective inspiral spin parameter, χ eff < -0.3. Nevertheless, the LIGO-Virgo-KAGRA (LVK) gravitational-wave (GW) detectors have yet to observe a BBH system with χ eff ≲ -0.2, leading to upper limits on the fraction of HM products in the population. We fit the astrophysical mass and spin distribution of BBH systems and measure the fraction of BBH systems with χ eff < -0.3, which implies an upper limit on the HM fraction. We find that fewer than 26% of systems in the underlying BBH population include HM products (90% credibility). Even among BBH systems with primary masses m 1 = 60 M ⊙, the HM fraction is less than 69%, which may constrain the location of the pair-instability mass gap. With 300 GW events (to be expected in the LVK's next observing run), if we fail to observe a BBH with χ eff < -0.3, we can conclude that the HM fraction is smaller than ${2.5}_{-2.2}^{+9.1} \% $ .

Keywords: gravitational wave astronomy; astrophysical black holes; stellar dynamics; massive stars; gravitational waves; gravitational wave sources; astrostatistics
Detection of Pairwise Kinetic Sunyaev–Zel'dovich Effect with DESI Galaxy Groups and Planck in Fourier Space

We report a ∼5.2σ detection of the kinetic Sunyaev–Zel'dovich (kSZ) effect in Fourier space, by combining the DESI galaxy groups and the Planck data. We use the density-weighted pairwise kSZ power spectrum as the summary statistic, and the detailed procedure of its measurement is presented in this paper. Meanwhile, we analyze the redshift space group density power spectrum to constrain its bias parameters and photo-z uncertainties. These best-fitted parameters are substituted to a nonlinear kSZ model, and we fit the measured kSZ power spectrum with this model to constrain the group optical depth $\bar{\tau }$ . Selected by a varying lower mass threshold M th, the galaxy group catalogs with different median masses ( $\tilde{M}$ ) are constructed from the Data Release 9 data of the DESI Legacy Imaging Surveys. $\tilde{M}$ spans a wide range of ∼1013–1014 M ⊙/h and the heaviest $\tilde{M}\sim {10}^{14}\ {M}_{\odot }/h$ is larger than those of most other kSZ detections. When the aperture photometric filter radius θ AP is set to be 4.'2, the $\tilde{M}=1.75\times {10}^{13}\ {M}_{\odot }/h$ group sample at the median redshift $\tilde{z}=0.64$ has the highest kSZ detection signal-to-noise ratio = 5.2. By fitting $\bar{\tau }{\rm{s}}$ from various samples against their $\tilde{M}$ s, we obtain a linear $\mathrm{log}\bar{\tau }-\mathrm{log}\tilde{M}$ relation: $\mathrm{log}\bar{\tau }=\gamma (\mathrm{log}\tilde{M}-14)+\mathrm{log}\beta $ , in which γ = 0.55 ± 0.1. We also vary the aperture photometric filter radius and measure the $\bar{\tau }$ profiles of group samples, whose constraints on the baryon distribution within and around dark matter halos will be discussed in a companion paper.

Keywords: cosmic microwave background radiation; sunyaev-zeldovich effect; large-scale structure of the universe
ALMA Observation of the Protoplanetary Disk around WW Cha: Faint Double-peaked Ring and Asymmetric Structure

We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 observations of dust continuum emission of the disk around WW Cha. The dust continuum image shows a smooth disk structure with a faint (low-contrast) dust ring, extending from ∼40 au to ∼70 au, not accompanied by any gap. We constructed the simple model to fit the visibility of the observed data by using the Markov Chain Monte Carlo (MCMC) method and found that the bump (we call the ring without the gap the bump) has two peaks at 40 au and 70 au. The residual map between the model and observation indicates asymmetric structures at the center and the outer region of the disk. These asymmetric structures are also confirmed by model-independent analysis of the imaginary part of the visibility. The asymmetric structure at the outer region is consistent with a spiral observed by SPHERE. To constrain physical quantities of the disk (dust density and temperature), we carried out radiative transfer simulations. We found that the midplane temperature around the outer peak is close to the freezing temperature of CO on water ice (∼30 K). The temperature around the inner peak is about 50 K, which is close to the freezing temperature of H2S and also close to the sintering temperature of several species. We also discuss the size distribution of the dust grains using the spectral index map obtained within the Band 6 data.

Keywords: observational astronomy; protoplanetary disks; circumstellar disks; circumstellar dust; planet formation
SRGA J181414.6-225604: A New Galactic Symbiotic X-Ray Binary Outburst Triggered by an Intense Mass-loss Episode of a Heavily Obscured Mira Variable

We present the discovery and multiwavelength characterization of SRGA J181414.6-225604, a Galactic hard X-ray transient discovered during the ongoing SRG/ART-XC sky survey. Using data from the Palomar Gattini-IR survey, we identify a spatially and temporally coincident variable infrared (IR) source, IRAS 18111-2257, and classify it as a very-late-type (M7-M8), long-period (1502 ± 24 days), and luminous (M K ≈ -9.9 ± 0.2) O-rich Mira donor star located at a distance of ≈14.6+2.9 -2.3 kpc. Combining multicolor photometric data over the last ≈25 yr, we show that the IR counterpart underwent a recent (starting ≈800 days before the X-ray flare) enhanced mass-loss (reaching ≈2.1 × 10-5 M ⊙ yr-1) episode, resulting in an expanding dust shell obscuring the underlying star. Multi-epoch follow-up observations from Swift, NICER, and NuSTAR reveal a ≈200 day long X-ray outburst reaching a peak luminosity of L X ≈ 2.5 × 1036 erg s-1, characterized by a heavily absorbed (N H ≈ 6 × 1022 cm-2) X-ray spectrum consistent with an optically thick Comptonized plasma. The X-ray spectral and timing behavior suggest the presence of clumpy wind accretion, together with a dense ionized nebula overabundant in silicate material surrounding the compact object. Together, we show that SRGA J181414.6-225604 is a new symbiotic X-ray binary in outburst, triggered by an intense dust-formation episode of a highly evolved donor. Our results offer the first direct confirmation for the speculated connection between enhanced late-stage donor mass loss and the active lifetimes of symbiotic X-ray binaries.

Keywords: x-ray surveys; near infrared astronomy; symbiotic binary stars; asymptotic giant branch stars; bondi accretion; circumstellar dust
Radio-loud Exoplanet-exomoon Survey: GMRT Search for Electron Cyclotron Maser Emission

We conducted the first dedicated search for signatures of exoplanet-exomoon interactions using the Giant Metrewave Radio Telescope (GMRT) as part of the radio-loud exoplanet-exomoon survey. Due to stellar tidal heating, irradiation, and subsequent atmospheric escape, candidate "exo-Io" systems are expected to emit up to 106 times more plasma flux than the Jupiter-Io DC circuit. This can induce detectable radio emission from the exoplanet-exomoon system. We analyze three "exo-Io" candidate stars: WASP-49, HAT-P 12, and HD 189733. We perform 12 hr phase-curve observations of WASP-49b at 400 MHz during primary & secondary transit, as well as first & third quadratures achieving a 3σ upper limit of 0.18 mJy beam-1 averaged over four days. HAT-P 12 was observed with GMRT at 150 and 325 MHz. We further analyzed the archival data of HD 189733 at 325 MHz. No emission was detected from the three systems. However, we place strong upper limits on radio flux density. Given that most exo-Io candidates orbit hot Saturns, we encourage more multiwavelength searches (in particular low frequencies) to span the lower range of exoplanet B-field strengths constrained here.

Keywords: natural satellites (extrasolar); radio continuum emission; exoplanets; star-planet interactions
On-sky Reconstruction of Keck Primary Mirror Piston Offsets Using a Zernike Wavefront Sensor

The next generation of large ground- and space-based optical telescopes will have segmented primary mirrors. Co-phasing the segments requires a sensitive wavefront sensor capable of measuring phase discontinuities. The Zernike wavefront sensor (ZWFS) is a passive wavefront sensor that has been demonstrated to sense segmented-mirror piston, tip, and tilt with picometer precision in laboratory settings. We present the first on-sky results of an adaptive optics fed ZWFS on a segmented aperture telescope, W.M. Keck Observatory's Keck II. Within the Keck Planet Imager and Characterizer light path, the ZWFS mask operates in the H band using an InGaAs detector (CRED2). We piston segments of the primary mirror by a known amount and measure the mirror's shape using both the ZWFS and a phase retrieval method on data acquired with the facility infrared imager, NIRC2. In the latter case, we employ slightly defocused NIRC2 images and a modified Gerchberg-Saxton phase retrieval algorithm to estimate the applied wavefront error. We find good agreement when comparing the phase retrieval and ZWFS reconstructions, with average measurements of 408 ± 23 and 394 ± 46 nm, respectively, for three segments pistoned by 400 nm of optical path difference (OPD). Applying various OPDs, we find that we are limited to ~100 nm OPD of applied piston, due to insufficient averaging of the adaptive optics residuals of our observations. We also present simulations of the ZWFS that help to explain the systematic offset observed in the ZWFS reconstructed data.

Keywords: astronomical instrumentation; astronomical methods; astronomical techniques; high angular resolution; direct imaging; observational astronomy