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1. Birds of a Feather: Resolving Stellar Mass Assembly with JWST/NIRCam in a Pair of Kindred z ∼ 2 Dusty Star-forming Galaxies Lensed by the PLCK G165.7+67.0 Cluster

   https://doi.org/10.3847/1538-4357/ad5d59  

   Kamieneski, Patrick S; Frye, Brenda L; Windhorst, Rogier A; Harrington, Kevin C; Yun, Min S; Noble, Allison; Pascale, Massimo; Foo, Nicholas; Cohen, Seth H; Jansen, Rolf A; et al (September 2024, The Astrophysical Journal)

   Abstract We present a new parametric lens model for the G165.7+67.0 galaxy cluster, which was discovered with Planck through its bright submillimeter flux, originating from a pair of extraordinary dusty star-forming galaxies (DSFGs) atz≈ 2.2. Using JWST and interferometric mm/radio observations, we characterize the intrinsic physical properties of the DSFGs, which are separated by only ∼1″ (8 kpc) and a velocity difference ΔV≲ 600 km s⁻¹in the source plane, and thus are likely undergoing a major merger. Boasting intrinsic star formation rates SFR_IR= 320 ± 70 and 400 ± 80M_⊙yr⁻¹, stellar masses of $\log \left[M_{\star }/M_{\odot }\right]=10.2\pm 0.1$and 10.3 ± 0.1, and dust attenuations ofA_V= 1.5 ± 0.3 and 1.2 ± 0.3, they are remarkably similar objects. We perform spatially resolved pixel-by-pixel spectral energy distribution (SED) fitting using rest-frame near-UV to near-IR imaging from JWST/NIRCam for both galaxies, resolving some stellar structures down to 100 pc scales. Based on their resolved specific star formation rates (SFRs) andUVJcolors, both DSFGs are experiencing significant galaxy-scale star formation events. If they are indeed interacting gravitationally, this strong starburst could be the hallmark of gas that has been disrupted by an initial close passage. In contrast, the host galaxy of SN H0pe has a much lower SFR than the DSFGs, and we present evidence for the onset of inside-out quenching and large column densities of dust even in regions of low specific SFR. Based on the intrinsic SFRs of the DSFGs inferred from UV through far-infrared SED modeling, this pair of objects alone is predicted to yield an observable 1.1 ± 0.2 core-collapse supernovae per year, making this cluster field ripe for continued monitoring. 

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2. TEMPLATES: Characterization of a Merger in the Dusty Lensing SPT0418–47 System

   https://doi.org/10.3847/1538-4357/ad33c9  

   Cathey, Jared; Gonzalez, Anthony_H; Lower, Sidney; Phadke, Kedar_A; Spilker, Justin; Aravena, Manuel; Bayliss, Matthew; Birkin, Jack_E; Birrer, Simon; Chapman, Scott; et al (May 2024, The Astrophysical Journal)

   Abstract We present JWST and Atacama Large Millimeter/submillimeter Array (ALMA) imaging for the lensing system SPT0418−47, which includes a strongly lensed, dusty, star-forming galaxy at redshiftz= 4.225 and an associated multiply imaged companion. The JWST NIRCam and MIRI imaging observations presented in this paper were acquired as part of the Early Release Science program Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star formation (TEMPLATES). This data set provides robust mutiwavelength detections of stellar light in both the main (SPT0418A) and companion (SPT0418B) galaxies, while the ALMA detection of [Cii] emission confirms that SPT0418B lies at the same redshift as SPT0418A. We infer that the projected physical separation of the two galaxies is 4.42 ± 0.05 kpc. We derive total magnifications ofμ= 29 ± 1 andμ= 4.1 ± 0.7 for SPT0418A and SPT0418B, respectively. We use bothprospectorandcigaleto derive stellar masses. We find that SPT0418A has a stellar mass of $M_{*}={3.4}_{-0.6}^{+1.1}\times {10}^{10}{M}_{\odot }$fromprospector orM_*= 1.5 ± 0.3 × 10¹⁰M_⊙fromcigale. The stellar mass ratio of SPT0418A and SPT0418B is roughly between 4 and 7 ( ${4.2}_{-1.6}^{+1.9}$forprospectorand 7.5 ± 3.7 forcigale). We see evidence of extended structure associated with SPT0418A that is suggestive of a tidal feature. These features, along with the close projected proximity, imply that the system is interacting. Interestingly, the star formation rates and stellar masses of both galaxies are consistent with the main sequence of star-forming galaxies at this epoch, indicating that this ongoing interaction has not noticeably elevated the star formation levels. 

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3. JWST Photometric Time-delay and Magnification Measurements for the Triply Imaged Type Ia “SN H0pe” at z = 1.78

   https://doi.org/10.3847/1538-4357/ad3c43  

   Pierel, J_D_R; Frye, B_L; Pascale, M.; Caminha, G_B; Chen, W.; Dhawan, S.; Gilman, D.; Grayling, M.; Huber, S.; Kelly, P.; et al (May 2024, The Astrophysical Journal)

   Abstract Supernova (SN) SN H0pe is a gravitationally lensed, triply imaged, Type Ia SN (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster of galaxies. Well-observed multiply imaged SNe provide a rare opportunity to constrain the Hubble constant (H₀), by measuring the relative time delay between the images and modeling the foreground mass distribution. SN H0pe is located atz= 1.783 and is the first SN Ia with sufficient light-curve sampling and long enough time delays for anH₀inference. Here we present photometric time-delay measurements and SN properties of SN H0pe. Using JWST/NIRCam photometry, we measure time delays of Δt_ab= $-{116.6}_{-9.3}^{+10.8}$observer-frame days and Δt_cb= $-{48.6}_{-4.0}^{+3.6}$observer-frame days relative to the last image to arrive (image 2b; all uncertainties are 1σ), which corresponds to a ∼5.6% uncertainty contribution forH₀assuming 70 km s⁻¹Mpc⁻¹. We also constrain the absolute magnification of each image toμ_a= ${4.3}_{-1.8}^{+1.6}$,μ_b= ${7.6}_{-2.6}^{+3.6}$,μ_c= ${6.4}_{-1.5}^{+1.6}$by comparing the observed peak near-IR magnitude of SN H0pe to the nonlensed population of SNe Ia. 

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4. 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)

   Abstract 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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5. The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High-contrast Imaging of the Exoplanet HIP 65426 b from 2 to 16 μm

   https://doi.org/10.3847/2041-8213/acd93e  

   Carter, Aarynn L.; Hinkley, Sasha; Kammerer, Jens; Skemer, Andrew; Biller, Beth A.; Leisenring, Jarron M.; Millar-Blanchaer, Maxwell A.; Petrus, Simon; Stone, Jordan M.; Ward-Duong, Kimberly; et al (July 2023, The Astrophysical Journal Letters)

   Abstract We present JWST Early Release Science coronagraphic observations of the super-Jupiter exoplanet, HIP 65426b, with the Near-Infrared Camera (NIRCam) from 2 to 5μm, and with the Mid-Infrared Instrument (MIRI) from 11 to 16μm. At a separation of ∼0.″82 (87 ${}_{-31}^{+108}$au), HIP 65426b is clearly detected in all seven of our observational filters, representing the first images of an exoplanet to be obtained by JWST, and the first-ever direct detection of an exoplanet beyond 5μm. These observations demonstrate that JWST is exceeding its nominal predicted performance by up to a factor of 10, depending on separation and subtraction method, with measured 5σcontrast limits of ∼1 × 10⁻⁵and ∼2 × 10⁻⁴at 1″ for NIRCam at 4.4μm and MIRI at 11.3μm, respectively. These contrast limits provide sensitivity to sub-Jupiter companions with masses as low as 0.3M_Jupbeyond separations of ∼100 au. Together with existing ground-based near-infrared data, the JWST photometry are fit well by aBT-SETTLatmospheric model from 1 to 16μm, and they span ∼97% of HIP 65426b's luminous range. Independent of the choice of model atmosphere, we measure an empirical bolometric luminosity that is tightly constrained between $\log \left(L_{\mathrm{bol}}/L_{\odot }\right)$= −4.31 and −4.14, which in turn provides a robust mass constraint of 7.1 ± 1.2M_Jup. In totality, these observations confirm that JWST presents a powerful and exciting opportunity to characterize the population of exoplanets amenable to high-contrast imaging in greater detail. 

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