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1. Reverberation Mapping of IC 4329A

   https://doi.org/10.3847/1538-4357/acab62  

   Bentz, Misty C.; Onken, Christopher A.; Street, Rachel; Valluri, Monica (February 2023, The Astrophysical Journal)

   Abstract We present the results of a new reverberation mapping campaign for the broad-line active galactic nucleus (AGN) in the edge-on spiral IC 4329A. Monitoring of the optical continuum withV-band photometry and broad emission-line flux variability with moderate-resolution spectroscopy allowed emission-line light curves to be measured for Hβ, Hγ, and Heiiλ4686. We find a time delay of ${16.3}_{-2.3}^{+2.6}$days for Hβ, a similar time delay of ${16.0}_{-2.6}^{+4.8}$days for Hγ, and an unresolved time delay of $-{0.6}_{-3.9}^{+3.9}$days for Heii. The time delay for Hβis consistent with the predicted value from the relationship between AGN luminosity and broad-line region radius, after correction for the ∼2.4 mag of intrinsic extinction at 5100 Å. Combining the measured time delay for Hβwith the broad emission-line width and an adopted value of 〈f〉 = 4.8, we find a central supermassive black hole mass of $M_{\mathrm{BH}}={6.8}_{-1.1}^{+1.2}\times {10}^7$M_⊙. Velocity-resolved time delays were measured across the broad Hβemission-line profile and may be consistent with an “M”-like shape. Modeling of the full reverberation response of Hβwas able to provide only modest constraints on some parameters, but does exhibit agreement with the black hole mass and average time delay. The models also suggest that the AGN structure is misaligned by a large amount from the edge-on galaxy disk. This is consistent with expectations from the unified model of AGNs, in which broad emission lines are expected to be visible only for AGNs that are viewed at relatively face-on inclinations. 

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2. The SDSS-V Black Hole Mapper Reverberation Mapping Project: Multiline Dynamical Modeling of a Highly Variable Active Galactic Nucleus with Decade-long Light Curves

   https://doi.org/10.3847/1538-4357/adfd4c  

   Stone, Zachary; Shen, Yue; Anderson, Scott F; Bauer, Franz; Brandt, W N; Chakraborty, Priyanka; Davis, Megan C; Fries, Logan B; Grier, Catherine J; Hall, P B; et al (September 2025, The Astrophysical Journal)

   Abstract We present dynamical modeling of the broad-line region (BLR) of the highly variable active galactic nucleus (AGN) SDSS J141041.25+531849.0 (z= 0.359) using photometric and spectroscopic monitoring data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping project and the current fifth-generation SDSS Black Hole Mapper program, spanning from early 2013 to early 2023. We model the geometry and kinematics of the BLR in the Hβ, Hα, and Mgiiemission lines for three different time periods to measure the potential change of structure within the BLR across time and line species. We find a moderately face-on $(i_{\mathrm{full}-\mathrm{state}}=29.{68}_{-3.62}^{+4.74}\mathrm{deg})$thick-disk $({\theta }_{\mathrm{opn},\mathrm{full}-\mathrm{state}}=42.{04}_{-3.96}^{+4.32}\mathrm{deg})$geometry for most BLRs, with a joint estimate for the mass of the supermassive black hole for each of three time periods, yielding ${\log }_{10}(M_{\mathrm{BH}}/M_{\odot })=8.10_{-0.03}^{+0.03}$when using the full data set. The inferred individual virial factorf∼ 1.6 is moderately smaller than the average factor for a local sample of dynamically modeled AGNs. There is strong evidence for nonvirial motion, with over 70% of clouds on inflowing/outflowing orbits. We analyze the change in model parameters across emission lines, finding the radii of BLRs for the emission lines are consistent with the following relative sizesR_Hβ ≲ R_MgII ≲ R_Hα. Comparing results across time, we findR_low-state ≲ R_high-state, with the change in BLR size for Hβbeing more significant than for the other two lines. The data also reveal complex, time-evolving, and potentially transient dynamics of the BLR gas over a decade-long timescale, encouraging for future dynamical modeling of fine-scale BLR kinematics. 

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3. GLIMPSE: An Ultrafaint ≃10 ⁵ M _⊙ Pop III Galaxy Candidate and First Constraints on the Pop III UV Luminosity Function at z  ≃  6–7

   https://doi.org/10.3847/1538-4357/ade9a1  

   Fujimoto, Seiji; Naidu, Rohan P; Chisholm, John; Atek, Hakim; Endsley, Ryan; Kokorev, Vasily; Furtak, Lukas J; Pan, Richard; Liu, Boyuan; Bromm, Volker; et al (August 2025, The Astrophysical Journal)

   Abstract Detecting the first generation of stars, Population III (Pop III), has been a long-standing goal in astrophysics, yet they remain elusive even in the JWST era. Here we present a novel NIRCam-based selection method for Pop III galaxies, and carefully validate it through completeness and contamination simulations. We systematically search ≃ 500 arcmin²across JWST legacy fields for Pop III candidates, including GLIMPSE, which, assisted by gravitational lensing, has produced JWST’s deepest NIRCam imaging thus far. We discover one promising Pop III galaxy candidate (GLIMPSE-16043) at $z=6.50_{-0.24}^{+0.03}$, a moderately lensed galaxy ( $\mu =2.9_{-0.2}^{+0.1}$) with an intrinsic UV magnitude of $M_{\mathrm{UV}}=-15.89_{-0.14}^{+0.12}$. It exhibits key Pop III features: strong Hαemission (rest-frame EW 2810 ± 550 Å); a Balmer jump; no dust (UV slopeβ = −2.34 ± 0.36); and undetectable metal lines (e.g., [Oiii]; [Oiii]/Hβ < 0.44), implying a gas-phase metallicity ofZ_gas/Z_⊙ < 0.5%. These properties indicate the presence of a nascent, metal-deficient young stellar population (<5 Myr) with a stellar mass of ≃10⁵M_⊙. Intriguingly, this source deviates significantly from the extrapolated UV–metallicity relation derived from recent JWST observations atz= 4–10, consistent with UV enhancement by a top-heavy Pop III initial mass function or the presence of an extremely metal-poor active galactic nucleus. We also derive the first observational constraints on the Pop III UV luminosity function atz ≃ 6–7. The volume density of GLIMPSE-16043 (≈10⁻⁴cMpc⁻³) is in excellent agreement with theoretical predictions, independently reinforcing its plausibility. This study demonstrates the power of our novel NIRCam method to finally reveal distant galaxies even more pristine than the Milky Way’s most metal-poor satellites, thereby promising to bring us closer to the first generation of stars than we have ever been before. 

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4. A Systematic Study of Ia-CSM Supernovae from the ZTF Bright Transient Survey

   https://doi.org/10.3847/1538-4357/acbc16  

   Sharma, Yashvi; Sollerman, Jesper; Fremling, Christoffer; Kulkarni, Shrinivas R.; De, Kishalay; Irani, Ido; Schulze, Steve; Strotjohann, Nora Linn; Gal-Yam, Avishay; Maguire, Kate; et al (May 2023, The Astrophysical Journal)

   Abstract Among the supernovae (SNe) that show strong interaction with a circumstellar medium (CSM), there is a rare subclass of Type Ia supernovae, SNe Ia-CSM, which show strong narrow hydrogen emission lines much like SNe IIn but on top of a diluted Type Ia spectrum. The only previous systematic study of this class identified 16 SNe Ia-CSM, eight historic and eight from the Palomar Transient Factory (PTF). Now using the successor survey to PTF, the Zwicky Transient Facility (ZTF), we have classified 12 additional SNe Ia-CSM through the systematic Bright Transient Survey (BTS). Consistent with previous studies, we find these SNe to have slowly evolving optical light curves with peak absolute magnitudes between −19.1 and −21, spectra having weak Hβand large Balmer decrements of ∼7. Out of the 10 SNe from our sample observed by NEOWISE, nine have 3σdetections, with some SNe showing a reduction in the red wing of Hα, indicative of newly formed dust. We do not find our SN Ia-CSM sample to have a significantly different distribution of equivalent widths of Heiλ5876 than SNe IIn as observed in Silverman et al. The hosts tend to be late-type galaxies with recent star formation. We derive a rate estimate of ${29}_{-21}^{+27}$Gpc⁻³yr⁻¹for SNe Ia-CSM, which is ∼0.02%–0.2% of the SN Ia rate. We also identify six ambiguous SNe IIn/Ia-CSM in the BTS sample and including them gives an upper limit rate of 0.07%–0.8%. This work nearly doubles the sample of well-studied Ia-CSM objects in Silverman et al., increasing the total number to 28. 

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5. CECILIA: The Faint Emission Line Spectrum of z ∼ 2–3 Star-forming Galaxies

   https://doi.org/10.3847/2041-8213/ad07dc  

   Strom, Allison L.; Rudie, Gwen C.; Trainor, Ryan F.; Brammer, Gabriel B.; Maseda, Michael V.; Raptis, Menelaos; Rogers, Noah S.; Steidel, Charles C.; Chen 陈, Yuguang 昱光; Law, David R. (November 2023, The Astrophysical Journal Letters)

   Abstract We present the first results from Chemical Evolution Constrained Using Ionized Lines in Interstellar Aurorae (CECILIA), a Cycle 1 JWST NIRSpec/MSA program that uses ultra-deep ∼30 hr G235M/F170LP observations to target multiple electron temperature-sensitive auroral lines in the spectra of 33 galaxies atz∼ 1–3. Using a subset of 23 galaxies, we construct two ∼600 object-hour composite spectra, both with and without the stellar continuum, and use these to investigate the characteristic rest-optical (λ_rest≈ 5700–8500 Å) spectrum of star-forming galaxies at the peak epoch of cosmic star formation. Emission lines of eight different elements (H, He, N, O, Si, S, Ar, and Ni) are detected, with most of these features observed to be ≲3% the strength of Hα. We report the characteristic strength of three auroral features ([Nii]λ5756, [Siii]λ6313, and [Oii]λλ7322, 7332), as well as other semi-strong and faint emission lines, including forbidden [Niii]λλ7380, 7414 and permitted Oiλ8449, some of which have never before been observed outside of the local Universe. Using these measurements, we findT_e[Nii] = 13,630 ± 2540 K, representing the first measurement of electron temperature using [Nii] in the high-redshift Universe. We also see evidence for broad line emission with a FWHM of ${536}_{-167}^{+45}$km s⁻¹; the broad component of Hαis 6.01%–28.31% the strength of the narrow component and likely arises from star-formation-driven outflows. Finally, we briefly comment on the feasibility of obtaining large samples of faint emission lines using JWST in the future. 

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