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1. CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

   https://doi.org/10.3847/1538-4357/ac1596  

   Abazajian, Kevork; Addison, Graeme E.; Adshead, Peter; Ahmed, Zeeshan; Akerib, Daniel; Ali, Aamir; Allen, Steven W.; Alonso, David; Alvarez, Marcelo; Amin, Mustafa A.; et al (February 2022, The Astrophysical Journal)

   Abstract CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r , in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5 σ , or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL. 

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2. Prospects for kSZ ² –21 cm ² Cross Correlations during Reionization

   https://doi.org/10.3847/1538-4357/adfb67  

   Zhou, Meng; La_Plante, Paul; Lidz, Adam; Mao, Yi; Ma, Yin-Zhe (September 2025, The Astrophysical Journal)

   Abstract The 21 cm line and the patchy kinetic Sunyaev–Zel’dovich (kSZ) effect are promising and complementary probes of the Epoch of Reionization. A challenge for cross correlating these two signals is that foreground avoidance or removal algorithms applied to the 21 cm data inevitably sacrifice Fourier modes with long wavelengths along the line of sight (i.e., low-k_∥modes), yet only these same modes contribute to the kSZ signal. Here we show that a suitable kSZ²× 21 cm²cross-correlation statistic nevertheless remains nonvanishing, even after filtering out the corrupted low-k_∥Fourier modes from the 21 cm data. We simulate the kSZ²× 21 cm²cross-correlation signal across reionization-era redshifts and find distinctive redshift evolution. This signal peaks early in the reionization history, when the volume-averaged fraction is around 0.1 ≲ x_HII ≲ 0.2, after which it changes sign and reaches a minimum near reionization’s midpoint (x_HII ∼ 0.5), while the signal gradually vanishes as reionization completes. These trends appear generic across three simulated models which differ in their reionization histories. We forecast the detectability of the kSZ²× 21 cm²cross-power spectrum for the HERA and SKA1-Low 21 cm experiments in combination with current and next-generation cosmic microwave background (CMB) surveys including the Simons Observatory, CMB-S4, and CMB-HD. We find that a high-significance detection (signal-to-noise ratio ≳ 5σ) is possible with SKA1-Low and CMB-S4. 

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3. A long-lasting eruption heralds SN 2023ldh, a clone of SN 2009ip

   https://doi.org/10.1051/0004-6361/202554858  

   Pastorello, A; Reguitti, A; Tartaglia, L; Valerin, G; Cai, Y-Z; Charalampopoulos, P; De_Luise, F; Dong, Y; Elias-Rosa, N; Farah, J; et al (September 2025, Astronomy & Astrophysics)

   We discuss the results of the spectroscopic and photometric monitoring of the type IIn supernova (SN) 2023ldh. Survey archive data show that the SN progenitor experienced erratic variability in the years before exploding. Beginning May 2023, the source showed a general slow luminosity rise that lasted for over four months, with some superposed luminosity fluctuations. In analogy toSN 2009ip, we call this brightening ‘Event A’. During Event A,SN 2023ldhreached a maximum absolute magnitude ofM_r = −15.52 ± 0.24 mag. The light curves then decreased by about 1 mag in all filters for about two weeks reaching a relative minimum, which was followed by a steep brightening (Event B) to an absolute peak magnitude ofM_r = −18.53 ± 0.23 mag, replicating the evolution ofSN 2009ipand similar to that of type IIn SNe. The three spectra ofSN 2023ldhobtained during Event A show multi-component P Cygni profiles of H I and Fe II lines. During the rise to the Event B peak, the spectrum shows a blue continuum dominated by Balmer lines in emission with Lorentzian profiles, with a full width at half maximum velocity of about 650 km s⁻¹. Later, in the post-peak phase, the spectrum reddens, and broader wings appear in the Hαline profile. Metal lines with P Cygni profiles and velocities of about 2000 km s⁻¹are clearly visible. Beginning around three months past maximum and until very late phases, the Ca II lines become among the most prominent features, while Hαis dominated by an intermediate-width component with a boxy profile. AlthoughSN 2023ldhmimics the evolution of otherSN 2009ip-like transients, it is slightly more luminous and has a slower photometric evolution. The surprisingly homogeneous observational properties ofSN 2009ip-like events may indicate similar explosion scenarios and similar progenitor parameters. 

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4. Syntrophotalea acetylenivorans sp. nov., a diazotrophic, acetylenotrophic anaerobe isolated from intertidal sediments

   https://doi.org/10.1099/ijsem.0.004698  

   Baesman, Shaun M; Sutton, John M; Fierst, Janna L; Akob, Denise M; Oremland, Ronald S (June 2019, International Journal of Systematic and Evolutionary Microbiology)

   A Gram-stain-negative, strictly anaerobic, non-motile, rod-shaped bacterium, designated SFB93^T, was isolated from the intertidal sediments of South San Francisco Bay, located near Palo Alto, CA, USA. SFB93^Twas capable of acetylenotrophic and diazotrophic growth, grew at 22–37 °C, pH 6.3–8.5 and in the presence of 10–45 g l⁻¹NaCl. Phylogenetic analyses based on 16S rRNA gene sequencing showed that SFB93^Trepresented a member of the genusSyntrophotaleawith highest 16S rRNA gene sequence similarities toSyntrophotalea acetylenicaDSM 3246^T(96.6 %),Syntrophotalea carbinolicaDSM 2380^T(96.5 %), andSyntrophotalea venetianaDSM 2394^T(96.7 %). Genome sequencing revealed a genome size of 3.22 Mbp and a DNA G+C content of 53.4 %. SFB93^Thad low genome-wide average nucleotide identity (81–87.5 %) and <70 % digital DNA–DNA hybridization value with other members of the genusSyntrophotalea. The phylogenetic position of SFB93^Twithin the familySyntrophotaleaceaeand as a novel member of the genusSyntrophotaleawas confirmed via phylogenetic reconstruction based on concatenated alignments of 92 bacterial core genes. On the basis of the results of phenotypic, genotypic and phylogenetic analyses, a novel species,Syntrophotalea acetylenivoranssp. nov., is proposed, with SFB93^T(=DSM 106009^T=JCM 33327^T=ATCC TSD-118^T) as the type strain. 

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5. Cosmology from LOFAR Two-metre Sky Survey Data Release 2: Cross-correlation with the cosmic microwave background

   https://doi.org/10.1051/0004-6361/202347728  

   Nakoneczny, S J; Alonso, D; Bilicki, M; Schwarz, D J; Hale, C L; Pollo, A; Heneka, C; Tiwari, P; Zheng, J; Brüggen, M; et al (January 2024, Astronomy & Astrophysics)

   Aims. We combined the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) second data release (DR2) catalogue with gravitational lensing maps from the cosmic microwave background (CMB) to place constraints on the bias evolution of LoTSS-detected radio galaxies, and on the amplitude of matter perturbations. Methods. We constructed a flux-limited catalogue from LoTSS DR2, and analysed its harmonic-space cross-correlation with CMB lensing maps fromPlanck,C_ℓ^gk, as well as its auto-correlation,C_ℓ^gg. We explored the models describing the redshift evolution of the large-scale radio galaxy bias, discriminating between them through the combination of bothC_ℓ^gkandC_ℓ^gg. Fixing the bias evolution, we then used these data to place constraints on the amplitude of large-scale density fluctuations, parametrised byσ₈. Results. We report the significance of theC_ℓ^gksignal at a level of 26.6σ. We determined that a linear bias evolution of the formb_g(z) =b_g,D/D(z), whereD(z) is the growth rate, is able to provide a good description of the data, and we measuredb_g,D= 1.41 ± 0.06 for a sample that is flux limited at 1.5 mJy, for scalesℓ< 250 forC_ℓ^gg, andℓ< 500 forC_ℓ^gk. At the sample’s median redshift, we obtainedb(z= 0.82) = 2.34 ± 0.10. Usingσ₈as a free parameter, while keeping other cosmological parameters fixed to thePlanckvalues, we found fluctuations of σ₈= 0.75_−0.04^+0.05. The result is in agreement with weak lensing surveys, and at 1σdifference withPlanckCMB constraints. We also attempted to detect the late-time-integrated Sachs-Wolfe effect with LOFAR data; however, with the current sky coverage, the cross-correlation with CMB temperature maps is consistent with zero. Our results are an important step towards constraining cosmology with radio continuum surveys from LOFAR and other future large radio surveys. 

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