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1. Search for Neutrino Emission from Hard X-Ray AGN with IceCube

   https://doi.org/10.3847/1538-4357/ada94b  

   Abbasi, R; Ackermann, M; Adams, J; Agarwalla, S K; Aguilar, J A; Ahlers, M; Alameddine, JM; Amin, N M; Andeen, K; Argüelles, C; et al (March 2025, The Astrophysical Journal)

   Abstract Active galactic nuclei (AGN) are promising candidate sources of high-energy astrophysical neutrinos, since they provide environments rich in matter and photon targets where cosmic-ray interactions may lead to the production of gamma rays and neutrinos. We searched for high-energy neutrino emission from AGN using the Swift-BAT Spectroscopic Survey catalog of hard X-ray sources and 12 yr of IceCube muon track data. First, upon performing a stacked search, no significant emission was found. Second, we searched for neutrinos from a list of 43 candidate sources and found an excess from the direction of two sources, the Seyfert galaxies NGC 1068 and NGC 4151. We observed NGC 1068 at flux ${\varphi }_{{\nu }_{\mu }+{\overline{\nu }}_{\mu }}$= $4.02_{-1.52}^{+1.58}\times 10^{-11}$TeV⁻¹cm⁻²s⁻¹normalized at 1 TeV, with a power-law spectral indexγ= 3.10 ${}_{-0.22}^{+0.26}$, consistent with previous IceCube results. The observation of a neutrino excess from the direction of NGC 4151 is at a posttrial significance of 2.9σ. If interpreted as an astrophysical signal, the excess observed from NGC 4151 corresponds to a flux ${\varphi }_{{\nu }_{\mu }+{\overline{\nu }}_{\mu }}$= $1.51_{-0.81}^{+0.99}\times 10^{-11}$TeV⁻¹cm⁻²s⁻¹normalized at 1 TeV andγ= 2.83 ${}_{-0.28}^{+0.35}$. 

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2. Measurement of CP asymmetry in $$ {\textrm{B}}_{\textrm{s}}^0\to {\textrm{D}}_{\textrm{s}}^{\mp }{\textrm{K}}^{\pm } $$ decays

   https://doi.org/10.1007/JHEP03(2025)139  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (March 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> A measurement of theCP-violating parameters in$$ {B}_s^0\boldsymbol{\to}{D}_s^{\mp }{K}^{\pm} $$ $B_s^0\to D_s^{\mp }{K}^{\pm }$decays is reported, based on the analysis of proton-proton collision data collected by the LHCb experiment corresponding to an integrated luminosity of 6 fb⁻¹at a centre-of-mass energy of 13 TeV. The measured parameters are obtained with a decay-time dependent analysis yieldingC_f= 0.791 ± 0.061 ± 0.022,$$ {A}_f^{\Delta \Gamma} $$ $A_f^{\text{∆}\Gamma }$= −0.051 ± 0.134 ± 0.058,$$ {A}_{\overline{f}}^{\Delta \Gamma} $$ $A_{\overline{f}}^{\text{∆}\Gamma }$= −0.303 ± 0.125 ± 0.055,S_f= −0.571 ± 0.084 ± 0.023 and$$ {S}_{\overline{f}} $$ $S_{\overline{f}}$= −0.503 ± 0.084 ± 0.025, where the first uncertainty is statistical and the second systematic. This corresponds to CP violation in the interference between mixing and decay of about 8.6σ. Together with the value of the$$ {B}_s^0 $$ $B_s^0$mixing phase −2β_s, these parameters are used to obtain a measurement of the CKM angleγequal to (74 ± 12)° modulo 180°, where the uncertainty contains both statistical and systematic contributions. This result is combined with the previous LHCb measurement in this channel using 3 fb⁻¹resulting in a determination of$$ \gamma ={\left({81}_{-11}^{+12}\right)}^{\circ } $$ $\gamma ={\left({81}_{-11}^{+12}\right)}^{\circ }$. 

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3. Validation of Elemental and Isotopic Abundances in Late-M Spectral Types with the Benchmark HIP 55507 AB System

   https://doi.org/10.3847/1538-4357/ad1243  

   Xuan, Jerry W; Wang, Jason; Finnerty, Luke; Horstman, Katelyn; Grimm, Simon; Peck, Anne E; Nielsen, Eric; Knutson, Heather A; Mawet, Dimitri; Isaacson, Howard; et al (February 2024, The Astrophysical Journal)

   Abstract M dwarfs are common host stars to exoplanets but often lack atmospheric abundance measurements. Late-M dwarfs are also good analogs to the youngest substellar companions, which share similarT_eff∼ 2300–2800 K. We present atmospheric analyses for the M7.5 companion HIP 55507 B and its K6V primary star with Keck/KPIC high-resolution (R∼ 35,000)K-band spectroscopy. First, by including KPIC relative radial velocities between the primary and secondary in the orbit fit, we improve the dynamical mass precision by 60% and find $M_B={88.0}_{-3.2}^{+3.4}{M}_{\mathrm{Jup}}$, putting HIP 55507 B above the stellar–substellar boundary. We also find that HIP 55507 B orbits its K6V primary star with $a={38}_{-3}^{+4}$au ande= 0.40 ± 0.04. From atmospheric retrievals of HIP 55507 B, we measure [C/H] = 0.24 ± 0.13, [O/H] = 0.15 ± 0.13, and C/O = 0.67 ± 0.04. Moreover, we strongly detect¹³CO (7.8σsignificance) and tentatively detect ${\mathrm{H}}_2^{18}\mathrm{O}$(3.7σsignificance) in the companion’s atmosphere and measure ${}^{12}\mathrm{CO}{/}^{13}\mathrm{CO}={98}_{-22}^{+28}$and ${\mathrm{H}}_2^{16}\mathrm{O}/{\mathrm{H}}_2^{18}\mathrm{O}={240}_{-80}^{+145}$after accounting for systematic errors. From a simplified retrieval analysis of HIP 55507 A, we measure ${}^{12}\mathrm{CO}{/}^{13}\mathrm{CO}={79}_{-16}^{+21}$and ${\mathrm{C}}^{16}\mathrm{O}/{\mathrm{C}}^{18}\mathrm{O}={288}_{-70}^{+125}$for the primary star. These results demonstrate that HIP 55507 A and B have consistent¹²C/¹³C and¹⁶O/¹⁸O to the <1σlevel, as expected for a chemically homogeneous binary system. Given the similar flux ratios and separations between HIP 55507 AB and systems with young substellar companions, our results open the door to systematically measuring¹³CO and ${\mathrm{H}}_2^{18}\mathrm{O}$abundances in the atmospheres of substellar or even planetary-mass companions with similar spectral types. 

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4. Optical and Radio Analysis of Systematically Classified Broad-lined Type Ic Supernovae from the Zwicky Transient Facility

   https://doi.org/10.3847/1538-4357/ad7fde  

   Srinivasaragavan, Gokul P; Yang, Sheng; Anand, Shreya; Sollerman, Jesper; Ho, Anna_Y Q; Corsi, Alessandra; Cenko, S Bradley; Perley, Daniel; Schulze, Steve; Sanchez-Fleming, Marquice; et al (November 2024, The Astrophysical Journal)

   Abstract We study a magnitude-limited sample of 36 broad-lined type Ic supernovae (SNe Ic-BL) from the Zwicky Transient Facility Bright Transient Survey (detected between 2018 March and 2021 August), which is the largest systematic study of SNe Ic-BL done in literature thus far. We present the light curves (LCs) for each of the SNe and analyze the shape of the LCs to derive empirical parameters, along with the explosion epochs for every event. The sample has an average absolute peak magnitude in therband of ${\overline{\mathit{M}}}_{\mathrm{r},\max }=-18.51\pm 0.15$mag. Using spectra obtained around peak light, we compute expansion velocities from the Feii5169 Å line for each event with high enough signal-to-noise ratio spectra, and find an average value of $\overline{v_{\mathrm{ph}}}=16,100\pm 1100$km s⁻¹. We also compute bolometric LCs, study the blackbody temperature and radii evolution over time, and derive the explosion properties of the SNe. The explosion properties of the sample have average values of ${\overline{\mathit{M}}}_{\mathrm{Ni}}={0.37}_{-0.06}^{+0.08}{\mathit{M}}_{\odot }$, ${\overline{\mathit{M}}}_{\mathrm{ej}}={2.45}_{-0.41}^{+0.47}{\mathit{M}}_{\odot }$, and ${\overline{\mathit{E}}}_{\mathrm{K}}=\left({4.02}_{-1.00}^{+1.37}\right)\times {10}^{51}$erg. Thirteen events have radio observations from the Very Large Array, with eight detections and five non-detections. We find that the populations that have radio detections and radio non-detections are indistinct from one another with respect to their optically inferred explosion properties, and there are no statistically significant correlations present between the events’ radio luminosities and optically inferred explosion properties. This provides evidence that the explosion properties derived from optical data alone cannot give inferences about the radio properties of SNe Ic-BL and likely their relativistic jet formation mechanisms. 

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5. Microphysics of Circumgalactic Turbulence Probed by Fast Radio Bursts and Quasars

   https://doi.org/10.3847/1538-4357/ade0bc  

   Ocker, Stella Koch; Chen, Mandy C; Oh, S Peng; Sharma, Prateek (July 2025, The Astrophysical Journal)

   Abstract The circumgalactic medium (CGM) is poorly constrained at the subparsec scales relevant to turbulent energy dissipation and regulation of multiphase structure. Fast radio bursts are sensitive to small-scale plasma density fluctuations, which can induce multipath propagation (scattering). The amount of scattering depends on the density fluctuation spectrum, including its amplitude $C_{\mathrm{n}}^2$, spectral indexβ, and dissipation scalel_i. We use quasar observations of CGM turbulence at ≳pc scales to infer $C_{\mathrm{n}}^2$, finding it to be $10^{-16}\lesssim C_{\mathrm{n}}^2\lesssim 10^{-9}$m^−20/3for hot (T> 10⁶K) gas and $10^{-8}\lesssim C_{\mathrm{n}}^2\lesssim 10^{-4}$m^−20/3for cool (10⁴≲T≲ 10⁵K) gas, depending on the gas sound speed and density. These values of $C_{\mathrm{n}}^2$are much smaller than those inferred in the interstellar medium at similar physical scales. The resulting scattering delays from the hot CGM are negligible (≪1μs at 1 GHz), but they are more detectable from the cool gas as either radio pulse broadening or scintillation, depending on the observing frequency and sightline geometry. Joint quasar-FRB observations of individual galaxies can yield lower limits onl_i, even if the CGM is not a significant scattering site. An initial comparison between quasar and FRB observations (albeit for different systems) suggestsl_i≳ 750 km in ∼10⁴K gas in order for the quasar and FRB constraints to be consistent. If a foreground CGM is completely ruled out as a source of scattering along an FRB sightline, thenl_imay be comparable to the smallest cloud sizes (≲pc) inferred from photoionization modeling of quasar absorption lines. 

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