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Gravitational waves emitted from compact binary coalescence can be subject to wave diffraction if they are gravitationally lensed by an intervening mass clump whose Schwarzschild time scale matches the wave period. Waves in the ground-based frequency band f∼10-103 Hz are sensitive to clumps with masses ME∼102-103 M enclosed within the impact parameter. These can be the central parts of low mass ML∼103-106 M dark matter halos, which are predicted in cold dark matter scenarios but are challenging to observe. Neglecting finely-tuned impact parameters, we focus on lenses aligned generally on the Einstein scale for which multiple lensed images may not form in the case of an extended lens. In this case, diffraction induces amplitude and phase modulations whose sizes ∼10%-20% are small enough so that standard matched filtering with unlensed waveforms do not degrade, but are still detectable for events with high signal-to-noise ratio. We develop and test an agnostic detection method based on dynamic programming, which does not require a detailed model of the lensed waveforms. For pseudo-Jaffe lenses aligned up to the Einstein radius, we demonstrate that a pair of fully upgraded aLIGO/Virgo detectors can extract diffraction imprints from binary black hole mergers out to zs∼0.2-0.3. The prospect will improve dramatically for a third-generation detector for which binary black hole mergers out to zs∼2-4 will all become valuable sources.

Numerical simulations indicate that correlations exist between the velocity distributions of stars and dark matter (DM). We study the local DM velocity distribution based on these correlations. We select K giants from LAMOST DR8 cross-matched with Gaia DR3, which have robust measurements of velocity and metallicity, and separate them into the disk, halo substructure, and isotropic halo components in the chemodynamical space utilizing the Gaussian mixture model. The substructure component is highly radially anisotropic and possibly related to the Gaia–Enceladus–Sausage (GES) merger event, while the isotropic halo component is accreted from the earliest mergers following the Maxwell–Boltzmann distribution (standard halo model [SHM]). We find that the GES-like substructure contributes ∼85% of the local nondisk stars in the solar neighborhood, which is nearly invariant when applying different volume cuts or additional angular momentum constraints. Utilizing the metallicity–stellar mass relation and the stellar mass–halo mass relation, we find that ∼ 25 − 15 + 24 % of local DM is in the kinematic substructure. Combined with the stellar distributions of nondisk components, we modify the heliocentric velocity distribution of local DM. It shifts to a lower speed with a sharper peak compared to the SHM and updates the detection limits of DM direct detection experiments. We discuss extensively the degeneracies present in the GMM fitting and propose that more kinematic and chemical information such as α abundance could help to break the degeneracy in the future. Our work confirms that the local DM velocity distribution deviates significantly from the SHM and needs to be properly accounted for in the DM detection experiments. [ABSTRACT FROM AUTHOR]

We investigate how the stellar rotational support changes as a function of spatially resolved stellar population age (⁠|$D_n4000$|⁠) and relative central stellar surface density (⁠|$\Delta \Sigma _1$|⁠) for MaNGA isolated/central disc galaxies. We find that the galaxy rotational support indicator |$\lambda _{R_\mathrm{e}}$| varies smoothly as a function of |$\Delta \Sigma _1$| and |$D_n4000$|⁠. |$D_n4000$| versus |$\Delta \Sigma _1$| follows a 'J-shape', with |$\lambda _{R_\mathrm{e}}$| contributing to the scatters. In this 'J-shaped' pattern rotational support increases with central |$D_n4000$| when |$\Delta \Sigma _1$| is low but decreases with |$\Delta \Sigma _1$| when |$\Delta \Sigma _1$| is high. Restricting attention to low- |$\Delta \Sigma _1$| (i.e. large-radius) galaxies, we suggest that the trend of increasing rotational support with |$D_n4000$| for these objects is produced by a mix of two different processes, a primary trend characterized by growth in |$\lambda _{R_\mathrm{e}}$| along with mass through gas accretion, on top of which disturbance episodes are overlaid, which reduce rotational support and trigger increased star formation. An additional finding is that star-forming galaxies with low |$\Delta \Sigma _1$| have relatively larger radii than galaxies with higher |$\Delta \Sigma _1$| at fixed stellar mass. Assuming that these relative radii rankings are preserved while galaxies are star forming then implies clear evolutionary paths in central |$D_n4000$| versus |$\Delta \Sigma _1$|⁠. The paper closes with comments on the implications that these paths have for the evolution of pseudo-bulges versus classical bulges. The utility of using |$\rm D_n4000$| – |$\Delta \Sigma _1$| to study |$\lambda _{R_\mathrm{e}}$| reinforces the notion that galaxy kinematics correlate both with structure and with stellar-population state, and indicates the importance of a multidimensional description for understanding bulge and galaxy evolution. [ABSTRACT FROM AUTHOR]

The Beijing-Arizona Sky Survey (BASS) is a new wide-field legacy imaging survey in the northern Galactic cap using the 2.3 m Bok telescope. The survey will cover about 5400 deg2 in the g and r bands, and the expected 5σ depths (corrected for the Galactic extinction) in these two bands are g = 24.0 and r = 23.4 mag (AB magnitude). BASS started observations in 2015 January and had completed about 41% of the area as of 2016 July. The first data release contains calibrated images obtained in 2015 and 2016 and their corresponding single-epoch and co-added catalogs. The actual depths of the single-epoch images are g ∼ 23.4 and r ∼ 22.9 mag. The full depths of the three epochs are g ∼ 24.1 and r ∼ 23.5 mag.

The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for 10,000 nearby galaxies at a spectral resolution of R ∼ 2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (R e) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5R e (Primary sample), and one-third of the sample is covered to 2.5R e (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically the point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ∼70 per 1.4 Å pixel for spectra stacked between 1R e and 1.5R e. Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals.

Using the final Mapping Nearby Galaxies at Apache Point Observatory sample of 10K galaxies, we investigate the dark matter (DM) fraction f DM within one half-light radius R e for about 6K galaxies with good kinematics spanning a wide range of morphologies and stellar velocity dispersion. We employ two techniques to estimate f DM: (i) Jeans anisotropic modelling (JAM), which performs DM decomposition based on stellar kinematics and (ii) comparing the total dynamical mass-to-light ratios (M / L)JAM and (M */ L)SPS from stellar population synthesis (SPS). We find that both methods consistently show a significant trend of increasing f DM with decreasing σe and low f DM at larger σe. For 235 early-type galaxies with the best models, we explore the variation of stellar initial mass function (IMF) by comparing the stellar mass-to-light ratios from JAM and SPS. We confirm that the stellar mass excess factor αIMF increases with σe, consistent with previous studies that reported a transition from Chabrier-like to Salpeter IMF among galaxies. We show that the αIMF trend cannot be driven by M */ L or IMF gradients as it persists when allowing for radial gradients in our model. We find no evidence for the total M / L increasing toward the centre. We detect weak positive correlations between αIMF and age, but no correlations with metallicity. We stack galaxy spectra according to their αIMF to search for differences in IMF-sensitive spectral features (e.g. the |$\rm Na_{\rm I}$| doublet). We only find marginal evidence for such differences, which casts doubt on the validity of one or both methods to measure the IMF. [ABSTRACT FROM AUTHOR]

The Thirty Meter Telescope (TMT) first light instrument IRIS (Infrared Imaging Spectrograph) will complete its preliminary design phase in 2016. The IRIS instrument design includes a near-infrared (0.85-2.4 micron) integral field spectrograph (IFS) and imager that are able to conduct simultaneous diffraction-limited observations behind the advanced adaptive optics system NFIRAOS. The IRIS science cases have continued to be developed and new science studies have been investigated to aid in technical performance and design requirements. In this development phase, the IRIS science team has paid particular attention to the selection of filters, gratings, sensitivities of the entire system, and science cases that will benefit from the parallel mode of the IFS and imaging camera. We present new science cases for IRIS using the latest end-To-end data simulator on the following topics: Solar System bodies, the Galactic center, active galactic nuclei (AGN), and distant gravitationally-lensed galaxies. We then briefly discuss the necessity of an advanced data management system and data reduction pipeline.

IRIS (InfraRed Imaging Spectrograph) is a first light near-infrared diffraction limited imager and integral field spectrograph being designed for the future Thirty Meter Telescope (TMT). IRIS is optimized to perform astronomical studies across a significant fraction of cosmic time, from our Solar System to distant newly formed galaxies (Barton et al. [1]). We present a selection of the innovative science cases that are unique to IRIS in the era of upcoming space and ground-based telescopes. We focus on integral field spectroscopy of directly imaged exoplanet atmospheres, probing fundamental physics in the Galactic Center, measuring 104 to 1010 M supermassive black hole masses, resolved spectroscopy of young star-forming galaxies (1 < 5) and first light galaxies (6 < 12), and resolved spectroscopy of strong gravitational lensed sources to measure dark matter substructure. For each of these science cases we use the IRIS simulator (Wright et al. [2], Do et al. [3]) to explore IRIS capabilities. To highlight the unique IRIS capabilities, we also update the point and resolved source sensitivities for the integral field spectrograph (IFS) in all five broadband filters (Z, Y, J, H, K) for the finest spatial scale of 0.004" per spaxel. We briefly discuss future development plans for the data reduction pipeline and quicklook software for the IRIS instrument suite.

We try to understand the trends in the mass density slopes as a function of galaxy properties. We use the results from the best Jeans Anisotropic Modelling (JAM) of the integral-field stellar kinematics for near 6000 galaxies from the MaNGA DynPop project, with stellar masses |$10^9\ {\rm {\rm M}_{\odot }}\lesssim M_*\lesssim 10^{12}\ {\rm {\rm M}_{\odot }}$|⁠ , including both early-type and late-type galaxies. We use the mass-weighted density slopes for the stellar |$\overline{\gamma }_*$|⁠ , dark |$\overline{\gamma }_{_{\rm DM}}$| and total |$\overline{\gamma }_{_{\rm T}}$| mass from the MaNGA DynPop project. As previously reported, |$\overline{\gamma }_{_{\rm T}}$| approaches a constant value of |$\overline{\gamma }_{_{\rm T}}\approx 2.2$| for high σe galaxies, and flattens for |$\lg (\sigma _{\rm e}/{\rm km\ s^{-1}})\lesssim 2.3$| galaxies, reaching |$\overline{\gamma }_{_{\rm T}}\approx 1.5$| for |$\lg (\sigma _{\rm e}/{\rm km\ s^{-1}})\approx 1.8$|⁠. We find that total and stellar slopes track each other tightly, with |$\overline{\gamma }_{_{\rm T}}\approx \overline{\gamma }_*-0.174$| over the full σe range. This confirms the dominance of stellar matter within R e. We also show that there is no perfect conspiracy between baryonic and dark matter, as |$\overline{\gamma }_*$| and |$\overline{\gamma }_{_{\rm DM}}$| do not vary inversely within the σe range. We find that the central galaxies from TNG50 and TNG100 simulations do not reproduce the observed galaxy mass distribution, which we attribute to the overestimated dark matter fraction, possibly due to a constant IMF and excessive adiabatic contraction effects in the simulations. Finally, we present the stacked dark matter density profiles and show that they are slightly steeper than the pure dark matter simulation prediction of |$\overline{\gamma }_{_{\rm DM}}\approx 1$|⁠ , suggesting moderate adiabatic contraction in the central region of galaxies. Our work demonstrates the power of stellar dynamics modelling for probing the interaction between stellar and dark matter and testing galaxy formation theories. [ABSTRACT FROM AUTHOR]

Peculiar motion of galaxies probes the structure growth in the universe. In this study, we employ the galaxy stellar mass-binding energy (massE) relation with only two nuisance parameters to build the largest peculiar-velocity (PV) catalogue to date, consisting of 229 890 ellipticals from the main galaxy sample (MGS) of the Sloan Digital Sky Survey (SDSS). We quantify the distribution of the massE-based distances in individual narrow redshift bins (dz  = 0.005), and then estimate the PV of each galaxy based on its offset from the Gaussian mean of the distribution. As demonstrated with the Uchuu-SDSS mock data, the derived PV and momentum power spectra are insensitive to accurate calibration of the massE relation itself, enabling measurements out to a redshift of 0.2, well beyond the current limit of z  = 0.1 using other galaxy scaling laws. We then measure the momentum power spectrum and demonstrate that it remains almost unchanged if varying significantly the redshift bin size within which the distance is measured, as well as the intercept and slope of the massE relation, respectively. By fitting the spectra using the perturbation theory model with four free parameters, f σ8 is constrained to f σ8 = 0.459 |$^{+0.068}_{-0.069}$|  over Δ z  = 0.02–0.2, 0.416 |$^{+0.074}_{-0.076}$|  over Δ z  = 0.02–0.1, and 0.526 |$^{+0.133}_{-0.148}$|  over Δ z  = 0.1–0.2. The error of f σ8 is 2.1 times smaller than that by the redshift space distortion (RSD) of the same sample. A Fisher matrix forecast illustrates that the constraint on f σ8 from the massE-based PV can potentially exceed that from the stage-IV RSD in late universe (z <0.5). [ABSTRACT FROM AUTHOR]

We present the measurement of total and stellar/dark matter decomposed mass density profile around a sample of galaxy groups and clusters with dynamical masses derived from integral-field stellar kinematics from the MaNGA survey in Paper I and weak lensing derived from the DECaLS imaging survey. Combining the two data sets enables accurate measurement of the radial density distribution from several kpc to Mpc scales. Intriguingly, we find that the excess surface density derived from stellar kinematics in the inner region cannot be explained by simply adding an NFW dark matter halo extrapolated from lensing measurement at a larger scale to a stellar mass component derived from the NASA-Sloan Atlas (NSA) catalogue. We find that a good fit to both data sets requires a stellar mass normalization about three times higher than that derived from the NSA catalogue, which would require an unrealistically too-heavy initial mass function for stellar mass estimation. If we keep the stellar mass normalization to that of the NSA catalogue but allow a varying inner dark matter density profile, we obtain an asymptotic slope of γgnfw =  |$1.82_{-0.25}^{+0.15}$| and γgnfw =  |$1.48_{-0.41}^{+0.20}$| for the group bin and the cluster bin, respectively, significantly steeper than the NFW case. We also compare the total mass inner density slopes with those from TNG300 and find that the values from the simulation are lower than the observation by about 2σ level. [ABSTRACT FROM AUTHOR]

We present dynamical scaling relations, combined with the stellar population properties, for a subsample of about 6000 nearby galaxies with the most reliable dynamical models extracted from the full Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) sample of 10 000 galaxies. We show that the inclination-corrected mass plane for both early-type galaxies (ETGs) and late-type galaxies (LTGs), which links dynamical mass, projected half-light radius R e, and the second stellar velocity moment σe within R e, satisfies the virial theorem and is even tighter than the uncorrected one. We find a clear parabolic relation between |$\lg (M/L)_{\rm e}$|⁠ , the total mass-to-light ratio (M / L) within a sphere of radius R e, and |$\lg \sigma _{\rm e}$|⁠ , with the M / L increasing with σe and for older stellar populations. However, the relation for ETGs is linear and the one for the youngest galaxies is constant. We confirm and improve the relation between mass-weighted total density slopes |$\overline{\gamma _{_{\rm T}}}$| and σe: |$\overline{\gamma _{_{\rm T}}}$| become steeper with increasing σe until |$\lg (\sigma _{\rm e}/{\rm km\, s^{-1}})\approx 2.2$| and then remain constant around |$\overline{\gamma _{_{\rm T}}}\approx 2.2$|⁠. The |$\overline{\gamma _{_{\rm T}}}\!-\!\sigma _{\rm e}$| variation is larger for LTGs than ETGs. At fixed σe the total density profiles steepen with galaxy age and for ETGs. We find generally low dark matter fractions, median f DM(< R e) = 8 per cent, within a sphere of radius R e. However, we find that f DM(< R e) depends on σe better than stellar mass: dark matter increases to a median f DM(< R e) = 33 per cent for galaxies with |$\sigma _{\rm e}\lesssim 100$|  km s−1. The increased f DM(< R e) at low σe explains the parabolic |$\lg (M/L)_{\rm e}\!-\!\lg \sigma _{\rm e}$| relation. [ABSTRACT FROM AUTHOR]

This is the second paper of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Dynamics and stellar Population (DynPop) series, which analyses the global stellar population, radial gradients, and non-parametric star-formation history of ∼10K galaxies from the MaNGA Survey final data release 17 and relates them with dynamical properties of galaxies. We confirm the correlation between the stellar population properties and the stellar velocity dispersion σe, but also find that younger galaxies are more metal-poor at fixed σe. Stellar age, metallicity, and mass-to-light ratio (M */ L) all decrease with increasing galaxy rotation, while their radial gradients become more negative (i.e. lower value at the outskirts). The exception is the slow rotators, which also appear to have significantly negative metallicity gradients, confirming the mass–metallicity gradient correlation. Massive disc galaxies in the green valley, on the |$(\sigma _{\rm e},\rm age)$| plane, show the most negative age and metallicity gradients, consistent with their old central bulges surrounded by young star-forming discs and metal-poor gas accretion. Galaxies with high σe, steep total mass-density slope, low dark matter fraction, high M */ L , and high metallicity have the highest star-formation rate at earlier times, and are currently quenched. We also discover a population of low-mass star-forming galaxies with low rotation but physically distinct from the massive slow rotators. A catalogue of these stellar population properties is provided publicly. [ABSTRACT FROM AUTHOR]

We analyse the integral field spectroscopy data for the ≈10 000 galaxies in final data release of the MaNGA survey. We identify 188 galaxies for which the emission lines cannot be described by single Gaussian components. These galaxies can be classified into (1) 38 galaxies with broad |$\rm H\alpha$| and [O  iii ]  |$\rm \lambda$| 5007 lines, (2) 101 galaxies with broad |$\rm H\alpha$| lines but no broad [O  iii ]  |$\rm \lambda$| 5007 lines, and (3) 49 galaxies with double-peaked narrow emission lines. Most of the broad-line galaxies are classified as active galactic nuclei (AGNs) from their line ratios. The catalogue helps us further understand the AGN-galaxy coevolution through the stellar population of broad-line region host galaxies and the relation between broad lines' properties and the host galaxies' dynamical properties. The stellar population properties (including mass, age, and metallicity) of broad-line host galaxies suggest there is no significant difference between narrow-line Seyfert-2 galaxies and Type-1 AGNs with broad |$\rm H\alpha$| lines. We use the broad- |$\rm H\alpha$| line width and luminosity to estimate masses of black hole in these galaxies, and test the M BH–σe relation in Type-1 AGN host galaxies. Furthermore, we find three dual AGN candidates supported by radio images from the VLA FIRST survey. This sample may be useful for further studies on AGN activities and feedback processes. [ABSTRACT FROM AUTHOR]

We present the observations and analysis of a high-magnification microlensing planetary event, KMT-2022-BLG-0440, for which the weak and short-lived planetary signal was covered by both the KMTNet survey and follow-up observations. The binary-lens models with a central caustic provide the best fits, with a planet/host mass ratio, q  = 0.75–1.00 × 10−4 at 1σ. The binary-lens models with a resonant caustic and a brown-dwarf mass ratio are both excluded by Δχ2 > 70. The binary-source model can fit the anomaly well but is rejected by the 'colour argument' on the second source. From Bayesian analyses, it is estimated that the host star is likely a K or M dwarf located in the Galactic disc, the planet probably has a Neptune-mass, and the projected planet-host separation is |$1.9^{+0.6}_{-0.7}$| or |$4.6^{+1.4}_{-1.7}$|  au, subject to the close/wide degeneracy. This is the third q < 10−4 planet from a high-magnification planetary signal (A ≳ 65). Together with another such planet, KMT-2021-BLG-0171Lb, the ongoing follow-up program for the KMTNet high-magnification events has demonstrated its ability to detect high-magnification planetary signals for q < 10−4 planets, which are challenging for the current microlensing surveys. [ABSTRACT FROM AUTHOR]

This is the first paper in our series on the combined analysis of the Dynamics and stellar Population (DynPop) for the MaNGA survey in the final SDSS Data Release 17 (DR17). Here, we present a catalogue of dynamically determined quantities for over 10 000 nearby galaxies based on integral-field stellar kinematics from the MaNGA survey. The dynamical properties are extracted using the axisymmetric Jeans Anisotropic Modelling (JAM) method, which was previously shown to be the most accurate for this kind of study. We assess systematic uncertainties using eight dynamical models with different assumptions. We use two orientations of the velocity ellipsoid: either cylindrically aligned JAMcyl or spherically aligned JAMsph. We also make four assumptions for the models' dark versus luminous matter distributions: (1) mass-follows-light, (2) free NFW dark halo, (3) cosmologically constrained NFW halo, (4) generalized NFW dark halo, i.e. with free inner slope. In this catalogue, we provide the quantities related to the mass distributions (e.g. the density slopes and enclosed mass within a sphere of a given radius for total mass, stellar mass, and dark matter mass components). We also provide the complete models which can be used to compute the full luminous and mass distribution of each galaxy. Additionally, we visually assess the qualities of the models to help with model selections. We estimate the observed scatter in the measured quantities which decreases as expected with improvements in quality. For the best data quality, we find a remarkable consistency of measured quantities between different models, highlighting the robustness of the results. [ABSTRACT FROM AUTHOR]

The number of identified fast radio bursts (FRBs) will continue to increase rapidly with current and planned future facilities. Strongly lensed FRBs are also expected to be found, which can provide precise time delays and thus have rich applications in cosmology and fundamental physics. However, the radio signal of lensed FRBs will be deflected by the plasma in lens galaxies in addition to the deflection by gravity. Such deflections by both gravity and plasma will cause frequency-dependent time delays, which are different from the dispersion delay and the geometric delay caused by gravitational lensing. Depending on the lensing and plasma models, the frequency–time-delay relationship of the lensed images can show distinguishing behaviours either between the multiple images or from the dispersion relation. Such phenomena cannot be neglected in future studies, especially at low radio frequencies, as plasma exists in lens galaxies in general. More importantly, such information provides not only a potential way to search for lensed FRBs but also constraints on the mass and plasma distributions in lens galaxies. In particular, plasma may make the missing central images observable at low radio frequencies. [ABSTRACT FROM AUTHOR]

Distance-redshift diagrams probe expansion history of the Universe. We show that the stellar mass-binding energy (massE) relation of galaxies proposed in our previous study offers a new distance ruler at cosmic scales. By using elliptical galaxies in the main galaxy sample of the Sloan Digital Sky Survey Data Release 7, we construct a distance-redshift diagram over the redshift range from 0.05 to 0.2 with the massE ruler. The best-fit dark energy density is 0.675 ± 0.079  for flat Λ-cold dark matter (ΛCDM) model, consistent with those by other probes. At the median redshift of 0.11, the median distance is estimated to have a fractional error of 0.34 per cent, much lower than those by supernova (SN) Ia and baryonic acoustic oscillation (BAO) and even exceeding their future capability at this redshift. The above low- |$\mathit{ z}$| measurement is useful for probing dark energy that dominates at the late Universe. For a flat dark energy equation of state model (flat w CDM), the massE alone constrains w to an error that is only a factor of 2.2, 1.7, and 1.3 times larger than those by BAO, SN Ia, and cosmic microwave background (CMB), respectively. [ABSTRACT FROM AUTHOR]

The galaxy is found to be in disequilibrium based on recent findings of the north/south (N/S) asymmetry and the phase mixing signatures, such as a phase spiral (snail) structure in the vertical phase space (z âˆ' V z ). We show that the N/S asymmetry in a tracer population of dwarfs may be quantitatively modeled with a simple phase snail model superimposed on a smooth equilibrium background. As the phase snail intersects with the z -axis, the number density is enhanced, and the velocity dispersion (σ z ) is decreased relative to the other side of the Galactic plane. Fitting only to the observed asymmetric N/S σ z profiles, we obtain reasonable parameters for the phase-space snail and the potential utilized in modeling the background, despite the complex dependence of the model on the potential parameters and the significant selection effects of the data. Both the snail shape and the N/S number density difference given by our best-fit model are consistent with previous observations. The equilibrium background implies a local dark matter density of 0.0151 âˆ' 0.0051 + 0.0050 M ⊙ pcâˆ'3. The vertical bulk motion of our model is similar to the observation, but with a ∼1.2 km sâˆ'1 shift. Our work demonstrates the strong correlation between the phase-space snail and the N/S asymmetry. Future observational constraints will facilitate more comprehensive snail models to unravel the Milky Way potential and the perturbation history encoded in the snail feature. [ABSTRACT FROM AUTHOR]

We report the complete statistical planetary sample from the prime fields (Γ ≥ 2 h−1) of the 2019 Korea Microlensing Telescope Network (KMTNet) microlensing survey. We develop the optimized KMTNet AnomalyFinder algorithm and apply it to the 2019 KMTNet prime fields. We find a total of 13 homogeneously selected planets and report the analysis of three planetary events, KMT-2019-BLG-(1042,1552,2974). The planet–host mass ratios, q , for the three planetary events are 6.34 × 10−4, 4.89 × 10−3, and 6.18 × 10−4, respectively. A Bayesian analysis indicates the three planets are all cold giant planets beyond the snow line of their host stars. The 13 planets are basically uniform in log  q over the range −5.0 < log  q < −1.5. This result suggests that the planets below q break = 1.7 × 10−4 proposed by the MOA-II survey may be more common than previously believed. This work is an early component of a large project to determine the KMTNet mass-ratio function, and the whole sample of 2016–2019 KMTNet events should contain about 120 planets. [ABSTRACT FROM AUTHOR]

We report the discovery and analysis of a planet in the microlensing event OGLE-2018-BLG-0799. The planetary signal was observed by several ground-based telescopes, and the planet-host mass ratio is q  = (2.65 ± 0.16) × 10−3. The ground-based observations yield a constraint on the angular Einstein radius θ E, and the microlensing parallax vector |$\boldsymbol{{\pi} }_{\rm E}$|⁠ , is strongly constrained by the Spitzer data. However, the 2019 Spitzer baseline data reveal systematics in the Spitzer photometry, so there is ambiguity in the magnitude of the parallax. In our preferred interpretation, a full Bayesian analysis using a Galactic model indicates that the planetary system is composed of an |$M_{\rm planet} = 0.26_{-0.11}^{+0.22}M_{\rm J}$| planet orbiting an |$M_{\rm host} = 0.093_{-0.038}^{+0.082}~\mathrm{M}_{\odot }$|⁠ , at a distance of |$D_{\rm L} = 3.71_{-1.70}^{+3.24}$|  kpc. An alternate interpretation of the data shifts the localization of the minima along the arc-shaped microlens parallax constraints. This, in turn, yields a more massive host with median mass of |$0.13 {\, \mathrm{M}_{\odot }}$| at a distance of 6.3 kpc. This analysis demonstrates the robustness of the osculating circles formalism, but shows that further investigation is needed to assess how systematics affect the specific localization of the microlens parallax vector and, consequently, the inferred physical parameters. [ABSTRACT FROM AUTHOR]

We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 d, identified through photometric measurements from the Transiting Exoplanet Survey Satellite (TESS) mission. The host star is located 33 pc away with a radius of R * = 0.34 ± 0.02 R⊙, a mass of |$0.34\pm 0.02 \, \mathrm{M}_{\odot }$|⁠ , and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 d based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multiwavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from Canada–France–Hawaii Telescope (CFHT)/SpectroPolarimètre InfraROUge (SPIRou). Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 R⊕ and a mass of 6.4 ± 2.4 M⊕. The mass and radius of TOI-2136 b are consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass-loss models, making it an interesting target for future studies of its interior structure and atmospheric properties. [ABSTRACT FROM AUTHOR]

The observed number counts of high-redshift galaxy candidates (1-8) have been used to build up a statistical description of star-forming activity at redshift z [??] 7, when galaxies reionized the Universe (1,2,9,10). Standard models11 predict that a high incidence of gravitational lensing will probably distort measurements of flux and number of these earliest galaxies. The raw probability of this happening has been estimated to be ~0.5 per cent (refs 11, 12), but can be larger owing to observational biases. Here we report that gravitational lensing is likely to dominate the observed properties of galaxies with redshifts of z [??] 12, when the instrumental limiting magnitude is expected to be brighter than the characteristic magnitude of the galaxy sample. The number counts could be modified by an order of magnitude' with most galaxies being part of multiply imaged systems, located less than 1 arcsec from brighter foreground galaxies at z ≅ 2. This lens-induced association of high-redshift and foreground galaxies has perhaps already been observed among a sample of galaxy candidates identified at z ≅ 10.6. Future surveys will need to be designed to account for a significant gravitational lensing bias in high-redshift galaxy samples., Along random lines of sight, the raw probability (or optical depth) of multiple imaging of objects at high redshifts--owing to gravitational lensing by individual foreground field galaxies (11,12)--is ~0.5%. However, [...]

Early-type galaxies (ETGs) possess total density profiles close to isothermal, which can lead to non-Gaussian line-of-sight velocity dispersion (LOSVD) under anisotropic stellar orbits. However, recent observations of local ETGs in the MASSIVE Survey reveal outer kinematic structures at 1.5 R eff (effective radius) that are inconsistent with fixed isothermal density profiles; the authors proposed varying density profiles as an explanation. We aim to verify this conjecture and understand the influence of stellar assembly on these kinematic features through mock ETGs in IllustrisTNG. We create mock Integral-Field-Unit observations to extract projected stellar kinematic features for 207 ETGs with stellar mass |$M_{\ast }\geqslant 10^{11} \, \mathrm{M_{\odot}}$| in TNG100-1. The mock observations reproduce the key outer (1.5 R eff) kinematic structures in the MASSIVE ETGs, including the puzzling positive correlation between velocity dispersion profile outer slope γouter and the kurtosis h 4's gradient. We find that h 4 is uncorrelated with stellar orbital anisotropy beyond R eff; instead, we find that the variations in γouter and outer h 4 (a good proxy for h 4 gradient) are both driven by variations of the density profile at the outskirts across different ETGs. These findings corroborate the proposed conjecture and rule out velocity anisotropy as the origin of non-Gaussian outer kinematic structure in ETGs. We also find that the outer kurtosis and anisotropy correlate with different stellar assembly components, with the former related to minor mergers or flyby interactions while the latter is mainly driven by major mergers, suggesting distinct stellar assembly origins that decorrelates the two quantities. [ABSTRACT FROM AUTHOR]

We report the discovery of TOI-530b, a transiting Saturn-like planet around an M0.5V dwarf, delivered by the Transiting Exoplanet Survey Satellite (TESS). The host star is located at a distance of 147.7 ± 0.6 pc with a radius of R * = 0.54 ± 0.03  R ⊙ and a mass of M * = 0.53 ± 0.02 M⊙. We verify the planetary nature of the transit signals by combining ground-based multiwavelength photometry, high-resolution spectroscopy from SPIRou as well as high-angular-resolution imaging. With V  = 15.4 mag, TOI-530b is orbiting one of the faintest stars accessible by ground-based spectroscopy. Our model reveals that TOI-530b has a radius of 0.83 ± 0.05  RJ and a mass of 0.37 ± 0.08  MJ on a 6.39-d orbit. TOI-530b is the sixth transiting giant planet hosted by an M-type star, which is predicted to be infrequent according to core accretion theory, making it a valuable object to further study the formation and migration history of similar planets. Furthermore, we identify a potential dearth of hot massive giant planets around M-dwarfs with separation distance smaller than 0.1 au and planet-to-star mass ratio between 2 × 10−3 and 10−2. We also find a possible correlation between hot giant planet formation and the metallicity of its parent M-dwarf. We discuss the potential formation channel of such systems. [ABSTRACT FROM AUTHOR]

The effect of ionized gas on the propagation of radio signals is known as plasma lensing. Unlike gravitational lensing, plasma lensing causes both magnification and strong de-magnification effects to background sources. We study the cross-section of plasma lensing for two density profiles, the Gaussian and power-law models. In general, the cross-section increases with the density gradient. Radio sources can be used to measure the free electron density along the line of sight. However, plasma lensing de-magnification causes an underestimate of the electron density. Such a bias increases with the electron density, and can be up to |$\sim 15{{\ {\rm per \ cent}}}$| in the high density region. There is a large probability that high density clumps will be missed due to this bias. The magnification of plasma lensing can also change the luminosity function of the background sources. The number density of sources on both the high- and low-luminosity ends can be overestimated due to this biasing effect. [ABSTRACT FROM AUTHOR]

The stellar mass-to-light ratio gradient in SDSS r -band ∇(M */ L r ) of a galaxy depends on its mass assembly history, which is imprinted in its morphology and gradients of age, metallicity, and stellar initial mass function (IMF). Taking a MaNGA sample of 2051 galaxies with stellar masses ranging from 109 to 1012 M ⊙ released in SDSS DR15, we focus on face-on galaxies, without merger and bar signatures, and investigate the dependence of the 2D ∇(M */ L r ) on other galaxy properties, including M */ L r -colour relationships by assuming a fixed Salpeter IMF as the mass normalization reference. The median gradient is ∇ M */ L r ∼ −0.1 (i.e. the M */ L r is larger at the centre) for massive galaxies, becomes flat around M * ∼ 1010 M ⊙ and change sign to ∇ M */ L r ∼ 0.1 at the lowest masses. The M */ L r inside a half-light radius increases with increasing galaxy stellar mass; in each mass bin, early-type galaxies have the highest value, while pure-disc late-type galaxies have the smallest. Correlation analyses suggest that the mass-weighted stellar age is the dominant parameter influencing the M */ L r profile, since a luminosity-weighted age is easily affected by star formation when the specific star formation rate (sSFR) inside the half-light radius is higher than 10−3 Gyr−1. With increased sSFR gradient, one can obtain a steeper negative ∇(M */ L r ). The scatter in the slopes of M */ L -colour relations increases with increasing sSFR, for example, the slope for post-starburst galaxies can be flattened to 0.45 from the global value 0.87 in the M */ L versus g − r diagram. Hence converting galaxy colours to M */ L should be done carefully, especially for those galaxies with young luminosity-weighted stellar ages, which can have quite different star formation histories. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate that stellar masses of galaxies (M star) are universally correlated through a double power-law function with the product of the dynamical velocities (V e) and sizes to one-fourth power (⁠|$R_{\rm e}^{0.25}$|⁠) of galaxies, both measured at the effective radii. The product |$V_{\rm e}R_{\rm e}^{0.25}$| represents the fourth root of the total binding energies within effective radii of galaxies. This stellar mass-binding energy correlation has an observed scatter of 0.14 dex in log(⁠|$V_{\rm e}R_{\rm e}^{0.25}$|⁠) and 0.46 dex in log(M star). It holds for a variety of galaxy types over a stellar mass range of nine orders of magnitude, with little evolution over cosmic time. A toy model of self-regulation between binding energies and supernovae feedback is shown to be able to reproduce the observed slopes, but the underlying physical mechanisms are still unclear. The correlation can be a potential distance estimator with an uncertainty of 0.2 dex independent of the galaxy type. [ABSTRACT FROM AUTHOR]

We report the discovery and characterization of a transiting warm sub-Neptune planet around the nearby bright (V  = 8.75 mag, K  = 7.15 mag) solar twin HD 183579, delivered by the Transiting Exoplanet Survey Satellite (TESS). The host star is located 56.8 ± 0.1 pc away with a radius of R * = 0.97 ± 0.02  R ⊙ and a mass of M * = 1.03 ± 0.05  M ⊙. We confirm the planetary nature by combining space and ground-based photometry, spectroscopy, and imaging. We find that HD 183579b (TOI-1055b) has a radius of R p = 3.53 ± 0.13  R ⊕ on a 17.47 d orbit with a mass of M p = 11.2 ± 5.4  M ⊕ (3σ mass upper limit of 27.4  M ⊕). HD 183579b is the fifth brightest known sub-Neptune planet system in the sky, making it an excellent target for future studies of the interior structure and atmospheric properties. By performing a line-by-line differential analysis using the high-resolution and signal-to-noise ratio HARPS spectra, we find that HD 183579 joins the typical solar twin sample, without a statistically significant refractory element depletion. [ABSTRACT FROM AUTHOR]

There is a population of stars with velocities in excess of 500 km s−1 relative to the Galactic center. Many, perhaps most, of these hypervelocity stars (HVSs) are B stars similar to the disk and S stars in a nuclear cluster around a supermassive black hole (SMBH) near Sgr A⋆. In Paper I of this series, we showed that the eccentricity of the stars emerged from a hypothetical disk around the SMBH that can be rapidly excited by the secular perturbation of its intermediate-mass companion (IMC), and we suggested IRS 13E as a potential candidate for the IMC. Here we show that this process leads to an influx of stars on parabolic orbits to the proximity of Sgr A⋆ on a secular timescale of a few megayears. This timescale is much shorter than the diffusion timescale into the lost cone through either the classical or the resonant relaxation. Precession of the highly eccentric stars' longitude of periastron, relative to that of the IMC, brings them to its proximity within a few megayears. The IMC's gravitational perturbation scatters a fraction of the stars from nearly parabolic to hyperbolic orbits with respect to the SMBH. Their follow-up close encounters with the SMBH induce them to escape with hypervelocity. This scenario is a variant of the hypothesis proposed by Hills based on the anticipated breakup of some progenitor binary stars in the proximity of the SMBH, and its main objective is to account for the limited life span of the known HVSs. We generalize our previous numerical simulations of this process with a much wider range of orbital configurations. We demonstrate the robustness and evaluate the efficiency of this channel of HVS formation. From these numerical simulations, we infer observable kinematic properties for the HVSs. [ABSTRACT FROM AUTHOR]

We present a method to compute the magnification of a finite source star lensed by a triple lens system based on the image boundary (contour integration) method. We describe a new procedure to obtain continuous image boundaries from solutions of the tenth-order polynomial obtained from the lens equation. Contour integration is then applied to calculate the image areas within the image boundaries, which yields the magnification of a source with uniform brightness. We extend the magnification calculation to limb-darkened stars approximated with a linear profile. In principle, this method works for all multiple lens systems, not just triple lenses. We also include an adaptive sampling and interpolation method for calculating densely covered light curves. The C++ source code and a corresponding python interface are publicly available. [ABSTRACT FROM AUTHOR]

A key feature of a large population of low-mass, late-type disc galaxies are star-forming discs with exponential light distributions. They are typically also associated with thin and flat morphologies, blue colours, and dynamically cold stars moving along circular orbits within co-planar thin gas discs. However, the latter features do not necessarily always imply the former, in fact, a variety of different kinematic configurations do exist. In this work, we use the cosmological hydrodynamical IllustrisTNG simulation to study the nature and origin of dynamically hot, sometimes even counter-rotating, star-forming disc galaxies in the lower stellar mass range (between |$5\times 10^9\, \mathrm{M_{\odot }}$| and |$2\times 10^{10}\, \mathrm{M_{\odot }}$|⁠). We find that being dynamically hot arises in most cases as an induced transient state, for example due to galaxy interactions and merger activities, rather than as an age-dependent evolutionary phase of star-forming disc galaxies. The dynamically hot but still actively star-forming discs show a common feature of hosting kinematically misaligned gas and stellar discs, and centrally concentrated on-going star formation. The former is often accompanied by disturbed gas morphologies, while the latter is reflected in low gas and stellar spins in comparison to their dynamically cold, normal disc counterparts. Interestingly, observed galaxies from MaNGA with kinematic misalignment between gas and stars show remarkably similar general properties as the IllustrisTNG galaxies, and therefore are plausible real-world counterparts. In turn, this allows us to make predictions for the stellar orbits and gas properties of these misaligned galaxies. [ABSTRACT FROM AUTHOR]

Galactic model plays an important role in the microlensing field, not only for analyses of individual events but also for statistics of the ensemble of events. However, the Galactic models used in the field vary, and some are unrealistically simplified. Here, we tested three Galactic disc dynamic models; the first is a simple standard model that was widely used in this field, the second model considers the radial dependence of the velocity dispersion, and the last model employs the asymmetric drift in the disc velocity distribution. We found that for a typical lens mass |$M_{\rm L}=0.5\, {\rm M}_\odot$|⁠ , the two new dynamical models predict |$\sim 16{{\ \rm per\ cent}}$| or |$\sim 5{{\ \rm per\ cent}}$| less long-time-scale events (e.g. microlensing time-scale t E > 300 d) and |$\sim 5{{\ \rm per\ cent}}$| and |$\sim 3.5{{\ \rm per\ cent}}$| more short-time-scale events (t E < 3 d) than the standard model. Moreover, the microlensing event rate as a function of Einstein radius θE or microlensing parallax πE also shows some model dependence (a few per cent). The two new models also have an impact on the total microlensing event rate. This result will also to some degree affect the Bayesian analysis of individual events, but overall, the impact is small. However, we still recommend that modellers should be more careful when choosing the Galactic model, especially in statistical works involving Bayesian analyses of a large number of events. Additionally, we find the asymptotic power-law behaviours in both θE and πE distributions, and we provide a simple model to understand them. [ABSTRACT FROM AUTHOR]

We revisit the stellar velocity distribution in the Galactic bulge/bar region with Apache Point Observatory Galactic Evolution Experiment DR16 and Gaia DR2, focusing in particular on the possible high-velocity (HV) peaks and their physical origin. We fit the velocity distributions with two different models, namely with Gauss–Hermite polynomials and Gaussian mixture models (GMMs). The result of the fit using Gauss–Hermite polynomials reveals a positive correlation between the mean velocity () and the "skewness" (h3) of the velocity distribution, possibly caused by the Galactic bar. The n = 2 GMM fitting reveals a symmetric longitudinal trend of ∣μ2∣ and σ2 (the mean velocity and the standard deviation of the secondary component), which is inconsistent with the x2 orbital family predictions. Cold secondary peaks could be seen at ∣l∣ ∼ 6°. However, with the additional tangential information from Gaia, we find that the HV stars in the bulge show similar patterns in the radial–tangential velocity distribution (VR–VT), regardless of the existence of a distinct cold HV peak. The observed VR–VT (or VGSR–μl) distributions are consistent with the predictions of a simple Milky Way bar model. The chemical abundances and ages inferred from ASPCAP and CANNON suggest that the HV stars in the bulge/bar are generally as old as, if not older than, the other stars in the bulge/bar region. [ABSTRACT FROM AUTHOR]

There is a dense group of OB and Wolf–Rayet stars within a fraction of a parsec from the supermassive black hole (SMBH) at the Galactic Center. These stars appear to be coeval and relatively massive. A subgroup of these stars orbits on the same plane. If they emerged with low- to modest-eccentricity orbits from a common gaseous disk around the central SMBH, their inferred life span would not be sufficiently long to account for the excitation of their high orbital eccentricity through dynamical relaxation. Here we analyze the secular perturbation of Galactic Center stars by an intermediate-mass companion (IMC) as a potential mechanism to account for these young disk stars' high eccentricity. This IMC may be either an intermediate-mass black hole or a compact cluster such as IRS 13E. If its orbital angular momentum vector is antiparallel to that of the disk stars, this perturbation would be effective in exciting the eccentricity of stars with orbital precession rates that resonate with the IMC's precession rate. If it orbits around the SMBH in the same direction as the disk stars, the eccentricity of the young stars can still be highly excited by the IMC during the depletion of their natal disk, possibly associated with the launch of the Fermi bubble. In this scenario, the IMC's precession rate decreases, and its secular resonance sweeps through the proximity of the young stars. We carry out numerical simulations with various inclination angles between the orbits of the IMC and the disk stars and show that this secular interaction is a robust mechanism to excite the eccentricity and inclination of some disk stars. [ABSTRACT FROM AUTHOR]

We introduce the LEnSed laeS in the Eboss suRvey (LESSER) project, which aims to search for lensed Lyman-α emitters (LAEs) in the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). The final catalogue contains 361 candidate lensing systems. The lens galaxies are luminous red galaxies (LRGs) at redshift 0.4 < z < 0.8, and the source galaxies are LAEs at redshift 2 < z < 3. The spectral resolution of eBOSS (∼2000) allows us to further identify the fine structures of Lyman-α (⁠|$\rm Ly\alpha$|⁠) emissions. Among our lensed LAE candidates, 281 systems present single-peaked line profiles while 80 systems show double-peaked features. Future spectroscopic/imaging follow-up observations of the catalogue may shed light on the origin of diverse |$\rm Ly\alpha$| line morphology, and provide promising labs for studying low-mass dark matter haloes/subhaloes. [ABSTRACT FROM AUTHOR]

We analyse the kinematics and spatial distribution of 15 599 fundamental-mode RR Lyrae (RRL) stars in the Milky Way bulge by combining OGLE-IV photometric data and Gaia DR2 proper motions. We show that the longitudinal proper motions and the line-of-sight velocities can give similar results for the rotation in the Galactic central regions. The angular velocity of bulge RRLs is found to be around 35 km s−1 kpc−1, significantly smaller than that for the majority of bulge stars (50–60 km s−1 kpc−1); bulge RRLs have larger velocity dispersion (120–140 km s−1) than younger stars. The dependence of the kinematics of the bulge RRLs on their metallicities is shown by their rotation curves and spatial distributions. Metal-poor RRLs ([Fe/H]<−1) show a smaller bar angle than metal-rich ones. We also find clues suggesting that RRLs in the bulge are not dominated by halo stars. These results might explain some previous conflicting results over bulge RRLs and help understand the chemodynamical evolution of the Galactic bulge. [ABSTRACT FROM AUTHOR]