Sudhagar Suyamprakasam (NCAC, Warsaw)
The successful detection of continuous gravitational waves (GWs) from spinning neutron stars (NSs) will shape our understanding of the physical properties of dense matter under extreme conditions. Binary population synthesis simulations show that forthcoming space-borne GW detectors may be capable of detecting some tight Galactic double NSs (DNSs) with 10-minute orbital periods. Successfully searching for continuous GWs from such a close DNS demands extremely precise waveform templates considering the interaction between the NS and its companion. Unlike the isolated formation channel, the DNSs from the dynamical formation channel have moderate to high orbital eccentricities. To accommodate these systems, we generalize the analytical waveforms from triaxial nonaligned NSs under spin-orbit coupling derived by Feng et al. [Phys. Rev. D 108, 063035 (2023) {this https URL}] to incorporate the effects of the orbital eccentricity. Our findings suggest that for DNSs formed through isolated binary evolution, the impact of eccentricity on the continuous GWs of their NSs can be neglected. In contrast, for DNSs formed through dynamical processes, it is necessary to consider eccentricity, as high-eccentricity orbits can result in a fitting factor of ≲0.97 within approximately 0.5 to 2 years of a coherent search. Once the GWs from spinning NSs in tight binaries are detected, the relative measurement accuracy of eccentricity can reach Δe/e∼O(10−7) for a signal-to-noise ratio of O(100) based on the Fisher information matrix, bearing significant implications for understanding the formation mechanisms of DNSs.
W.-F. Feng et al.: https://arxiv.org/abs/2410.09540
Krzysztof Nalewajko (NCAC, Warsaw)
Based on https://arxiv.org/abs/2410.19061 from Vos, Cerutti, Mościbrodzka & Parfrey (Oct 2024)
Sarang Shashikant Shah (NCAC, Warsaw)
Based on https://arxiv.org/pdf/2412.12792 from Saini & Pandey (Dec 2024)
Angelos Karakonstantakis (NCAC, Warsaw)
Based on https://arxiv.org/abs/2501.04094 from Golden et al. (Jan 2025)
Weronika Narloch (NCAC, Warsaw)
based on https://arxiv.org/pdf/2412.09783 from Clontz et al. (Dec 2024)
Vincent Hocdé (NCAC, Warsaw)
Cepheid circumstellar emissions have previously been detected via both infrared excess and infrared interferometric observations at a few stellar radii. Those studies have shown that these circumstellar emission can be produced by ionized gas, however there is no direct observational evidence to confirm this hypothesis. In this letter we explore the continuum emission and a spectrum of the bright and long-period Cepheid, ℓ~Car (P=35.56day) at millimeter-wavelengths in order to detect possible effects of ionized gas emission. We presented ALMA observations of ℓ Car in two spectral setups in Band~6 (near 212 and 253\,GHz, respectively) and we compared the measured flux density to one expected for the stellar continuum. We also derived the spectral index and probed the presence of Radio Recombination Lines (RRL). We report statistically significant emission of about 3.5mJy in the two spectral ranges, which is about 2.5 times the stellar continuum emission. For the first time, we are also able to derive the spectral index of the flux density (Sν∝να), α=+1.26±0.44 (∼3σ error), which is characteristic of partially optically thick ionized gas emission. Additionally, we discovered an emission line from a RRL of hydrogen H29α centered on the stellar rest velocity, smaller in spatial extent than about 0\farcs2 (≲100AU), with a symmetric profile with a width at half power of 55.3±7.5\,\kms (1σ error). It confirms the presence of ionized gas emission near ℓ~Car. The millimeter emission detected from ℓ Car can be attributed to ionized gas emission from the Cepheid's chromosphere. Further radio interferometric observations are necessary to confirm the occurrence of these ionized gas envelopes around Cepheids of different pulsation periods.
Andrzej Sołtan (NCAC, Warsaw)
https://arxiv.org/abs/2501.19236 (Unveiling the largest structures in the nearby Universe: Discovery of the Quipu superstructure)
Felipe Espinoza Arancibia (NCAC, Warsaw)
Based on https://arxiv.org/abs/2501.09076 from Espinoza-Arancibia & Pilecki (Jan 2025)
Wen Xuan Sia (NCAC, Warsaw)
Based on https://arxiv.org/pdf/2501.07521 from Antonopoulou et al. (Jan 2025)
Abbas Askar (NCAC, Warsaw)
based on https://arxiv.org/abs/2502.00102 from Han et al. (Mar 2025)
Agata Różańska (NCAC, Warsaw)
Parikshit Partha Biswas (NCAC, Warsaw)
Based on: https://ui.adsabs.harvard.edu/abs/2025MNRAS.537L..55S/abstract
