Peculiar motion of galaxies probes the structure growth in the universe. In this study, we employ the galaxy stellar massbinding energy (massE) relation with only two nuisance parameters to build the largest peculiarvelocity (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 massEbased 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 UchuuSDSS 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, fσ8 is constrained to fσ8 = 0.459$^{+0.068}_{0.069}$ over Δz = 0.02–0.2, 0.416$^{+0.074}_{0.076}$ over Δz = 0.02–0.1, and 0.526$^{+0.133}_{0.148}$ over Δz = 0.1–0.2. The error of fσ8 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 fσ8 from the massEbased PV can potentially exceed that from the stageIV RSD in late universe (z<0.5).
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ABSTRACT 
ABSTRACT Distanceredshift diagrams probe expansion history of the Universe. We show that the stellar massbinding 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 distanceredshift diagram over the redshift range from 0.05 to 0.2 with the massE ruler. The bestfit dark energy density is 0.675 ± 0.079 for flat Λcold 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 wCDM), 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.

Aims. We inspect the four microlensing events KMT2021BLG1968, KMT2021BLG2010, KMT2022BLG0371, and KMT2022BLG1013, for which the light curves exhibit partially covered shortterm central anomalies. We conduct detailed analyses of the events with the aim of revealing the nature of the anomalies. Methods. We tested various models that can explain the anomalies of the individual events, including the binarylens (2L1S) and binarysource (1L2S) interpretations. Under the 2L1S interpretation, we thoroughly inspected the parameter space to determine the existence of degenerate solutions, and if they existed, we tested whether the degeneracy could be resolved. Results. We find that the anomalies in KMT2021BLG2010 and KMT2022BLG1013 are uniquely defined by planetarylens interpretations with planettohost mass ratios of q ~ 2.8 × 10 −3 and ~1.6 × 10 −3 , respectively. For KMT2022BLG0371, a planetary solution with a mass ratio q ~ 4 × 10 −4 is strongly favored over the other three degenerate 2L1S solutions with different mass ratios based on the χ 2 and relative proper motion arguments, and a 1L2S solution is clearly ruled out. For KMT2021BLG1968, on the other hand, we find that the anomaly can be explained either by a planetary or a binarysource interpretation, making it difficult to firmly identify the nature of the anomaly. From the Bayesian analyses of the identified planetary events, we estimate that the masses of the planet and host are ( M p / M J , M h / M ⊙ ) = (1.07 −0.68 +1.15 , 0.37 −0.23 +0.40 ), (0.26 −0.11 +0.13 , 0.63 −0.28 +0.32 ), and (0.31 −0.16 +0.46 , 0.18 −0.10 +0.28 ) for KMT2021BLG2010L, KMT2022BLG0371L, and KMT2022BLG1013L, respectively.more » « lessFree, publiclyaccessible full text available June 1, 2024

ABSTRACT Earlytype galaxies (ETGs) possess total density profiles close to isothermal, which can lead to nonGaussian lineofsight velocity dispersion (LOSVD) under anisotropic stellar orbits. However, recent observations of local ETGs in the MASSIVE Survey reveal outer kinematic structures at 1.5Reff (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 IntegralFieldUnit observations to extract projected stellar kinematic features for 207 ETGs with stellar mass $M_{\ast }\geqslant 10^{11} \, \mathrm{M_{\odot}}$ in TNG1001. The mock observations reproduce the key outer (1.5Reff) kinematic structures in the MASSIVE ETGs, including the puzzling positive correlation between velocity dispersion profile outer slope γouter and the kurtosis h4’s gradient. We find that h4 is uncorrelated with stellar orbital anisotropy beyond Reff; instead, we find that the variations in γouter and outer h4 (a good proxy for h4 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 nonGaussian 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 In this work, we update and develop algorithms for KMTNet tenderlove care (TLC) photometry in order to create a new, mostly automated, TLC pipeline. We then start a project to systematically apply the new TLC pipeline to the historic KMTNet microlensing events, and search for buried planetary signals. We report the discovery of such a planet candidate in the microlensing event MOA2019BLG421/KMT2019BLG2991. The anomalous signal can be explained by either a planet around the lens star or the orbital motion of the source star. For the planetary interpretation, despite many degenerate solutions, the planet is most likely to be a Jovian planet orbiting an M or K dwarf, which is a typical microlensing planet. The discovery proves that the project can indeed increase the sensitivity of historic events and find previously undiscovered signals.

Abstract We present the analysis of seven microlensing planetary events with planet/host mass ratios q < 10 −4 : KMT2017BLG1194, KMT2017BLG0428, KMT2019BLG1806, KMT2017BLG1003, KMT2019BLG1367, OGLE2017BLG1806, and KMT2016BLG1105. They were identified by applying the Korea Microlensing Telescope Network (KMTNet) AnomalyFinder algorithm to 2016–2019 KMTNet events. A Bayesian analysis indicates that all the lens systems consist of a cold superEarth orbiting an M or K dwarf. Together with 17 previously published and three that will be published elsewhere, AnomalyFinder has found a total of 27 planets that have solutions with q < 10 −4 from 2016–2019 KMTNet events, which lays the foundation for the first statistical analysis of the planetary massratio function based on KMTNet data. By reviewing the 27 planets, we find that the missing planetary caustics problem in the KMTNet planetary sample has been solved by AnomalyFinder. We also find a desert of highmagnification planetary signals ( A ≳ 65), and a followup project for KMTNet highmagnification events could detect at least two more q < 10 −4 planets per year and form an independent statistical sample.more » « less

Aims. We investigate the data collected by the highcadence microlensing surveys during the 2022 season in search of planetary signals appearing in the light curves of microlensing events. From this search, we find that the lensing event MOA2022BLG249 exhibits a brief positive anomaly that lasted for about one day, with a maximum deviation of ~0.2 mag from a singlesource, singlelens model. Methods. We analyzed the light curve under the two interpretations of the anomaly: one originated by a lowmass companion to the lens (planetary model) and the other originated by a faint companion to the source (binarysource model). Results. We find that the anomaly is better explained by the planetary model than the binarysource model. We identified two solutions rooted in the innerouter degeneracy and for both of them, the estimated planettohost mass ratio, q ~ 8 × 10 −5 , is very small. With the constraints provided by the microlens parallax and the lower limit on the Einstein radius, as well as the blendflux constraint, we find that the lens is a planetary system, in which a superEarth planet, with a mass of (4.83 ± 1.44) Μ ⊕ , orbits a lowmass host star, with a mass of (0.18 ± 0.05) M ⊙ , lying in the Galactic disk at a distance of (2.00 ± 0.42) kpc. The planet detection demonstrates the elevated microlensing sensitivity of the current highcadence lensing surveys to lowmass planets.more » « lessFree, publiclyaccessible full text available June 1, 2024

ABSTRACT We present the observations and analysis of a highmagnification microlensing planetary event, KMT2022BLG0440, for which the weak and shortlived planetary signal was covered by both the KMTNet survey and followup observations. The binarylens 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 binarylens models with a resonant caustic and a browndwarf mass ratio are both excluded by Δχ2 > 70. The binarysource 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 Neptunemass, and the projected planethost 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 highmagnification planetary signal (A ≳ 65). Together with another such planet, KMT2021BLG0171Lb, the ongoing followup program for the KMTNet highmagnification events has demonstrated its ability to detect highmagnification planetary signals for q < 10−4 planets, which are challenging for the current microlensing surveys.more » « lessFree, publiclyaccessible full text available May 11, 2024

Abstract We complete the publication of all microlensing planets (and “possible planets”) identified by the uniform approach of the KMT AnomalyFinder system in the 21 KMT subprime fields during the 2019 observing season, namely, KMT2019BLG0298, KMT2019BLG1216, KMT2019BLG2783, OGLE2019BLG0249, and OGLE2019BLG0679 (planets), as well as OGLE2019BLG0344 and KMT2019BLG0304 (possible planets). The five planets have mean log mass ratio measurements of (−2.6, −3.6, −2.5, −2.2, −2.3), median mass estimates of (1.81, 0.094, 1.16, 7.12, 3.34)
M _{Jup}, and median distance estimates of (6.7, 2.7, 5.9, 6.4, 5.6) kpc, respectively. The main scientific interest of these planets is that they complete the AnomalyFinder sample for 2019, which has a total of 25 planets that are likely to enter the statistical sample. We find statistical consistency with the previously published 33 planets from the 2018 AnomalyFinder analysis according to an ensemble of five tests. Of the 58 planets from 2018–2019, 23 were newly discovered by AnomalyFinder. Within statistical precision, half of the planets have caustic crossings, while half do not; an equal number of detected planets result from major and minorimage lightcurve perturbations; and an equal number come from KMT prime fields versus subprime fields. 
Abstract We analyze the MOA2020BLG208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA2020BLG208Lb, with an estimated subSaturn mass. With a mass ratio q = 3.17 − 0.26 + 0.28 × 10 − 4 , the planet lies near the peak of the massratio function derived by the MOA collaboration and near the edge of expected sample sensitivity. For these estimates we provide results using two masslaw priors: one assuming that all stars have an equal planethosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass m planet = 46 − 24 + 42 M ⊕ and a host star of mass M host = 0.43 − 0.23 + 0.39 M ⊙ , located at a distance D L = 7.49 − 1.13 + 0.99 kpc . For the second scenario, we estimate m planet = 69 − 34 + 37 M ⊕ , M host = 0.66 − 0.32 + 0.35 M ⊙ , and D L = 7.81 − 0.93 + 0.93 kpc . The planet has a projected separation as a fraction of the Einstein ring radius s = 1.3807 − 0.0018 + 0.0018 . As a cool subSaturnmass planet, this planet adds to a growing collection of evidence for revised planetary formation models.more » « lessFree, publiclyaccessible full text available March 24, 2024