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1. Two Massive, Compact, and Dust-obscured Candidate z ≃ 8 Galaxies Discovered by JWST

   https://doi.org/10.3847/1538-4357/acef21  

   Akins, Hollis B. ; Casey, Caitlin M. ; Allen, Natalie ; Bagley, Micaela B. ; Dickinson, Mark ; Finkelstein, Steven L. ; Franco, Maximilien ; Harish, Santosh ; Arrabal Haro, Pablo ; Ilbert, Olivier ; et al ( October 2023 , The Astrophysical Journal)

   We present a search for extremely red, dust-obscured,z> 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin²of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277W−F444W (∼2.5 mag) and detection in MIRI/F770W (∼25 mag), we identify two galaxies, COS-z8M1 and CEERS-z7M1, that have best-fit photometric redshifts of$z={8.4}_{-0.4}^{+0.3}$and${7.6}_{-0.1}^{+0.1}$, respectively. We perform spectral energy distribution fitting with a variety of codes (includingbagpipes,prospector,beagle, andcigale) and find a >95% probability that these indeed lie atz> 7. Both sources are compact (R_eff≲ 200 pc) and highly obscured (A_V∼ 1.5–2.5) and, at our best-fit redshift estimates, likely have strong [Oiii]+Hβemission contributing to their 4.4μm photometry. We estimate stellar masses of ∼10¹⁰M_⊙for both sources; by virtue of detection in MIRI at 7.7μm, these measurements are robust to the inclusion of bright emission lines, for example, from an active galactic nucleus. We identify a marginal (2.9σ) Atacama Large Millimeter/submillimeter Array detection at 2 mm within 0.″5 of COS-z8M1, which, if real, would suggest a remarkably high IR luminosity of ∼10¹²L_⊙. These two galaxies, if confirmed atz∼ 8, would be extreme in their stellar and dust masses and may be representative of a substantial population of highly dust-obscured galaxies at cosmic dawn.

    

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2. TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration

   https://doi.org/10.3847/1538-3881/ac5c4f  

   Tran, Quang H. ; Bowler, Brendan P. ; Endl, Michael ; Cochran, William D. ; MacQueen, Phillip J. ; Gandolfi, Davide ; Persson, Carina M. ; Fridlund, Malcolm ; Palle, Enric ; Nowak, Grzegorz ; et al ( April 2022 , The Astronomical Journal)

   We report the discovery of two transiting planets around the bright (V= 9.9 mag) main-sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune ($R_{\mathrm{b}}={2.06}_{-0.15}^{+0.19}$R_⊕) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter ($R_{\mathrm{c}}={0.987}_{-0.025}^{+0.025}$R_Jup) on a 40.7 day orbit. Using radial velocity observations gathered with the Tull Coudé Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of$M_{\mathrm{c}}={0.63}_{-0.08}^{+0.09}$M_Jupfor the outer warm Jupiter, implying a mean density of${\rho }_c={0.81}_{-0.11}^{+0.13}$g cm⁻³. The inner sub-Neptune is undetected in our radial velocity data (M_b< 0.13M_Jupat the 99% confidence level). Multiplanet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit ($e_{\mathrm{c}}={0.09}_{-0.04}^{+0.05}$) and one or more inner coplanar planets are more consistent with “gentle” formation mechanisms such as disk migration or in situ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, eight (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of in situ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.

    

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3. Morphologies of Galaxies at z ≳ 9 Uncovered by JWST/NIRCam Imaging: Cosmic Size Evolution and an Identification of an Extremely Compact Bright Galaxy at z ∼ 12

   https://doi.org/10.3847/1538-4357/acd44a  

   Ono, Yoshiaki ; Harikane, Yuichi ; Ouchi, Masami ; Yajima, Hidenobu ; Abe, Makito ; Isobe, Yuki ; Shibuya, Takatoshi ; Wise, John H. ; Zhang, Yechi ; Nakajima, Kimihiko ; et al ( July 2023 , The Astrophysical Journal)

   We present morphologies of galaxies atz≳ 9 resolved by JWST/NIRCam 2–5μm imaging. Our sample consists of 22 galaxy candidates identified by stringent dropout and photo-zcriteria in GLASS, CEERS, SMACS J0723, and Stephan’s Quintet flanking fields, one of which has been spectroscopically identified atz= 11.44. We perform surface brightness (SB) profile fitting with GALFIT for six bright galaxies with a signal-to-noise ratio = 10–40 on an individual basis and for stacked faint galaxies with secure point-spread functions (PSFs) of the NIRCam real data, carefully evaluating systematics by Monte Carlo simulations. We compare our results with those of previous JWST studies, and confirm that the effective radiir_eof our measurements are consistent with those of previous measurements atz∼ 9. We obtainr_e≃ 200–300 pc with the exponential-like profiles, Sérsic indexes ofn≃ 1–1.5, for galaxies atz∼ 12–16, indicating that the relation ofr_e∝ (1 +z)^sfor$s=-{1.22}_{-0.16}^{+0.17}$explains cosmic evolution overz∼ 0–16 for$\sim L_{z=3}^{*}$galaxies. One bright (M_UV= −21 mag) galaxy atz∼ 12, GL-z12-1, has an extremely compact profile withr_e= 39 ± 11 pc that is surely extended over the PSF. Even in the case that the GL-z12-1 SB is fit by active galactic nuclei + galaxy composite profiles, the best-fit galaxy component is again compact,$r_{\mathrm{e}}={48}_{-15}^{+38}$pc, which is significantly (>5σ) smaller than the typicalr_evalue atz∼ 12. Compared with numerical simulations, we find that such a compact galaxy naturally forms atz≳ 10, and that frequent mergers at the early epoch produce more extended galaxies following ther_e∝ (1 +z)^srelation.

    

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4. The Stellar Mass–Black Hole Mass Relation at z ∼ 2 down to BH∼107M⊙ Determined by HETDEX

   https://doi.org/10.3847/1538-4357/acc2c2  

   Zhang, Yechi ; Ouchi, Masami ; Gebhardt, Karl ; Liu, Chenxu ; Harikane, Yuichi ; Cooper, Erin Mentuch ; Davis, Dustin ; Farrow, Daniel J. ; Gawiser, Eric ; Hill, Gary J. ; et al ( May 2023 , The Astrophysical Journal)

   We investigate the stellar mass–black hole mass (${\mathit{}}_{*}–{\mathit{}}_{\mathrm{BH}}$) relation with type 1 active galactic nuclei (AGNs) down to${\mathit{}}_{\mathrm{BH}}={10}^7{M}_{\odot }$, corresponding to a ≃ −21 absolute magnitude in rest-frame ultraviolet, atz= 2–2.5. Exploiting the deep and large-area spectroscopic survey of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX), we identify 66 type 1 AGNs with${\mathit{}}_{\mathrm{BH}}$ranging from 10⁷–10¹⁰M_⊙that are measured with single-epoch virial method using Civemission lines detected in the HETDEX spectra.${\mathit{}}_{*}$of the host galaxies are estimated from optical to near-infrared photometric data taken with Spitzer, the Wide-field Infrared Survey Explorer, and ground-based 4–8 m class telescopes byCIGALEspectral energy distribution (SED) fitting. We further assess the validity of SED fitting in two cases by host-nuclear decomposition performed through surface brightness profile fitting on spatially resolved host galaxies with the James Webb Space Telescope/NIRCam CEERS data. We obtain the${\mathit{}}_{*}–{\mathit{}}_{\mathrm{BH}}$relation covering the unexplored low-mass ranges of${\mathit{}}_{\mathrm{BH}}\sim {10}^7–{10}^8{M}_{\odot }$, and conduct forward modeling to fully account for the selection biases and observational uncertainties. The intrinsic${\mathit{}}_{*}–{\mathit{}}_{\mathrm{BH}}$relation atz∼ 2 has a moderate positive offset of 0.52 ± 0.14 dex from the local relation, suggestive of more efficient black hole growth at higher redshift even in the low-mass regime of${\mathit{}}_{\mathrm{BH}}\sim {10}^7–{10}^8{M}_{\odot }$. Our${\mathit{}}_{*}–{\mathit{}}_{\mathrm{BH}}$relation is inconsistent with the${\mathit{}}_{\mathrm{BH}}$suppression at the low-${\mathit{}}_{*}$regime predicted by recent hydrodynamic simulations at a 98% confidence level, suggesting that feedback in the low-mass systems may be weaker than those produced in hydrodynamic simulations.

    

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5. The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and Its Implications for Structure Growth

   https://doi.org/10.3847/1538-4357/acfe06  

   Qu, Frank J. ; Sherwin, Blake D. ; Madhavacheril, Mathew S. ; Han, Dongwon ; Crowley, Kevin T. ; Abril-Cabezas, Irene ; Ade, Peter A. R. ; Aiola, Simone ; Alford, Tommy ; Amiri, Mandana ; et al ( February 2024 , The Astrophysical Journal)

   We present new measurements of cosmic microwave background (CMB) lensing over 9400 deg²of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB data set, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at 2.3% precision (43σsignificance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure that our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. Our CMB lensing power spectrum measurement provides constraints on the amplitude of cosmic structure that do not depend on Planck or galaxy survey data, thus giving independent information about large-scale structure growth and potential tensions in structure measurements. The baseline spectrum is well fit by a lensing amplitude ofA_lens= 1.013 ± 0.023 relative to the Planck 2018 CMB power spectra best-fit ΛCDM model andA_lens= 1.005 ± 0.023 relative to the ACT DR4 + WMAP best-fit model. From our lensing power spectrum measurement, we derive constraints on the parameter combination$S_8^{\mathrm{CMBL}}\equiv {\sigma }_8{\left({\mathrm{\Omega }}_m/0.3\right)}^{0.25}$of$S_8^{\mathrm{CMBL}}=0.818\pm 0.022$from ACT DR6 CMB lensing alone and$S_8^{\mathrm{CMBL}}=0.813\pm 0.018$when combining ACT DR6 and PlanckNPIPECMB lensing power spectra. These results are in excellent agreement with ΛCDM model constraints from Planck or ACT DR4 + WMAP CMB power spectrum measurements. Our lensing measurements from redshiftsz∼ 0.5–5 are thus fully consistent with ΛCDM structure growth predictions based on CMB anisotropies probing primarilyz∼ 1100. We find no evidence for a suppression of the amplitude of cosmic structure at low redshifts.

    

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