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1. Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions

   https://doi.org/10.3847/1538-4357/ad7bb1  

   Rybicki, Krzysztof A; Shvartzvald, Yossi; Yee, Jennifer C; Calchi_Novati, Sebastiano; Ofek, Eran O; Bond, Ian A; Beichman, Charles; Bryden, Geoff; Carey, Sean; Henderson, Calen; et al (November 2024, The Astrophysical Journal)

   Abstract In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of ${3.0}_{-1.3}^{+1.8}{M}_{\odot }$, ${4.7}_{-2.1}^{+3.2}{M}_{\odot }$, ${3.15}_{-0.64}^{+0.66}{M}_{\odot }$and ${1.40}_{-0.55}^{+0.75}{M}_{\odot }$, respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale (t_E) versus parallax (π_E) diagram to derive constraints on the population of lenses in general and massive remnants in particular. 

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2. OGLE-2019-BLG-1180Lb: Discovery of a Wide-orbit Jupiter-mass Planet around a Late-type Star

   https://doi.org/10.3847/1538-3881/ad0723  

   Chung, Sun-Ju; Udalski, Andrzej; Yee, Jennifer C.; Gould, Andrew; Leading Authors; Albrow, Michael D.; Jung, Youn Kil; Hwang, Kyu-Ha; Han, Cheongho; Ryu, Yoon-Hyun; et al (November 2023, The Astronomical Journal)

   Abstract We report on the discovery and analysis of the planetary microlensing event OGLE-2019-BLG-1180 with a planet-to-star mass ratioq∼ 0.003. The event OGLE-2019-BLG-1180 has unambiguous cusp-passing and caustic-crossing anomalies, which were caused by a wide planetary caustic withs≃ 2, wheresis the star–planet separation in units of the angular Einstein radiusθ_E. Thanks to well-covered anomalies by the Korea Micorolensing Telescope Network (KMTNet), we measure both the angular Einstein radius and the microlens parallax in spite of a relatively short event timescale oft_E= 28 days. However, because of a weak constraint on the parallax, we conduct a Bayesian analysis to estimate the physical lens parameters. We find that the lens system is a super-Jupiter-mass planet of $M_{\mathrm{p}}={1.75}_{-0.51}^{+0.53}{M}_{\mathrm{J}}$orbiting a late-type star of $M_{\mathrm{h}}={0.55}_{-0.26}^{+0.27}{M}_{\odot }$at a distance $D_{\mathrm{L}}={6.1}_{-1.3}^{+0.9}\mathrm{kpc}$. The projected star–planet separation is $a_{\perp }={5.19}_{-1.23}^{+0.90}\mathrm{au}$, which means that the planet orbits at about four times the snow line of the host star. Considering the relative lens–source proper motion ofμ_rel= 6 mas yr⁻¹, the lens will be separated from the source by 60 mas in 2029. At that time one can measure the lens flux from adaptive optics imaging of Keck or a next-generation 30 m class telescope. OGLE-2019-BLG-1180Lb represents a growing population of wide-orbit planets detected by KMTNet, so we also present a general investigation into prospects for further expanding the sample of such planets. 

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3. COOL-LAMPS. VI. Lens Model and New Constraints on the Properties of COOL J1241+2219, a Bright z = 5 Lyman Break Galaxy and its z = 1 Cluster Lens

   https://doi.org/10.3847/1538-4357/ad22de  

   Klein, Maxwell; Sharon, Keren; Napier, Kate; Gladders, Michael D; Khullar, Gourav; Bayliss, Matthew; Dahle, Håkon; Owens, M Riley; Stark, Antony; Brownsberger, Sasha; et al (February 2024, The Astrophysical Journal)

   Abstract We present a strong lensing analysis of COOL J1241+2219, the brightest known gravitationally lensed galaxy atz≥ 5, based on new multiband Hubble Space Telescope (HST) imaging data. The lensed galaxy has a redshift ofz= 5.043, placing it shortly after the end of the “Epoch of Reionization,” and an AB magnitudez_AB= 20.47 mag (Khullar et al.). As such, it serves as a touchstone for future research of that epoch. The high spatial resolution of HST reveals internal structure in the giant arc, from which we identify 15 constraints and construct a robust lens model. We use the lens model to extract the cluster mass and lensing magnification. We find that the mass enclosed within the Einstein radius of thez= 1.001 cluster lens is $M(<5.″77)={1.079}_{-0.007}^{+0.023}\times {10}^{13}{M}_{☉}$, significantly lower than other known strong lensing clusters at its redshift. The average magnification of the giant arc is 〈μ_arc〉 = ${76}_{-20}^{+40}$, a factor of ${2.4}_{-0.7}^{+1.4}$greater than previously estimated from ground-based data; the flux-weighted average magnification is 〈μ_arc〉 = ${92}_{-31}^{+37}$. We update the current measurements of the stellar mass and star formation rate (SFR) of the source for the revised magnification to $\log \left(M_{\star }/M_{\odot }\right)=$9.7 ± 0.3 and SFR = ${10.3}_{-4.4}^{+7.0}$M_⊙yr⁻¹, respectively. The powerful lensing magnification acting upon COOL J1241+2219 resolves the source and enables future studies of the properties of its star formation on a clump-by-clump basis. The lensing analysis presented here will support upcoming multiwavelength characterization with HST and JWST data of the stellar mass assembly and physical properties of this high-redshift lensed galaxy. 

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4. Unveiling MOA-2007-BLG-192: An M Dwarf Hosting a Likely Super-Earth

   https://doi.org/10.3847/1538-3881/ad5444  

   Terry, Sean K; Beaulieu, Jean-Philippe; Bennett, David P; Hamdorf, Euan; Bhattacharya, Aparna; Chaudhry, Viveka; Cole, Andrew A; Koshimoto, Naoki; Anderson, Jay; Bachelet, Etienne; et al (July 2024, The Astronomical Journal)

   Abstract We present an analysis of high-angular-resolution images of the microlensing target MOA-2007-BLG-192 using Keck adaptive optics and the Hubble Space Telescope. The planetary host star is robustly detected as it separates from the background source star in nearly all of the Keck and Hubble data. The amplitude and direction of the lens–source separation allows us to break a degeneracy related to the microlensing parallax and source radius crossing time. Thus, we are able to reduce the number of possible binary-lens solutions by a factor of ∼2, demonstrating the power of high-angular-resolution follow-up imaging for events with sparse light-curve coverage. Following Bennett et al., we apply constraints from the high-resolution imaging on the light-curve modeling to find host star and planet masses ofM_host= 0.28 ± 0.04M_☉and $m_p={12.49}_{-8.03}^{+65.47}{M}_{\oplus }$at a distance from Earth ofD_L= 2.16 ± 0.30 kpc. This work illustrates the necessity for the Nancy Grace Roman Galactic Exoplanet Survey to use its own high-resolution imaging to inform light-curve modeling for microlensing planets that the mission discovers. 

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5. The Sloan Digital Sky Survey Reverberation Mapping Project: The Black Hole Mass–Stellar Mass Relations at 0.2 ≲ z ≲ 0.8

   https://doi.org/10.3847/1538-4357/acddda  

   Li, Jennifer_I-Hsiu; Shen, Yue; Ho, Luis_C; Brandt, W_N; Grier, Catherine_J; Hall, Patrick_B; Homayouni, Y.; Koekemoer, Anton_M; Schneider, Donald_P; Trump, Jonathan_R (September 2023, The Astrophysical Journal)

   Abstract We measure the correlation between black hole massM_BHand host stellar massM_*for a sample of 38 broad-line quasars at 0.2 ≲z≲ 0.8 (median redshiftz_med= 0.5). The black hole masses are derived from a dedicated reverberation mapping program for distant quasars, and the stellar masses are derived from two-band optical+IR Hubble Space Telescope imaging. Most of these quasars are well centered within ≲1 kpc from the host galaxy centroid, with only a few cases in merging/disturbed systems showing larger spatial offsets. Our sample spans two orders of magnitude in stellar mass (∼10⁹–10¹¹M_⊙) and black hole mass (∼10⁷–10⁹M_⊙) and reveals a significant correlation between the two quantities. We find a best-fit intrinsic (i.e., selection effects corrected)M_BH–M_*,hostrelation of $\log \left(M_{\mathrm{BH}}/M_{\odot }\right)={7.01}_{-0.33}^{+0.23}+{1.74}_{-0.64}^{+0.64}\log \left(M_{*,\mathrm{host}}/{10}^{10}{M}_{\odot }\right)$, with an intrinsic scatter of ${0.47}_{-0.17}^{+0.24}$dex. Decomposing our quasar hosts into bulges and disks, there is a similarM_BH–M_*,bulgerelation with slightly larger scatter, likely caused by systematic uncertainties in the bulge–disk decomposition. TheM_BH–M_*,hostrelation atz_med= 0.5 is similar to that in local quiescent galaxies, with negligible evolution over the redshift range probed by our sample. With direct black hole masses from reverberation mapping and the large dynamical range of the sample, selection biases do not appear to affect our conclusions significantly. Our results, along with other samples in the literature, suggest that the locally measured black hole mass–host stellar mass relation is already in place atz∼ 1. 

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