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Arxiv_Daily_Notice/2025-05-05-Arxiv-Daily-Paper.md

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+# Showing new listings for Monday, 5 May 2025
+Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.
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+
+阅读 `Usage.md`了解如何使用此repo实现个性化的Arxiv论文推送
+
+See `Usage.md` for instructions on how to personalize the repo. 
+
+
+Keyword list: ['star formation', 'star-forming', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']
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+Excluded: ['galaxies', 'galaxy cluster', ' AGN ']
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+
+### Today: 8papers 
+#### Can planet-planet binaries survive in star-forming regions?
+ - **Authors:** Richard J. Parker, Simon P. Goodwin, Jessica L. Diamond (University of Sheffield, UK)
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
+ - **Arxiv link:** https://arxiv.org/abs/2505.00762
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.00762
+
+ - **Abstract**
+ Significant numbers of free-floating planetary-mass objects have been discovered in nearby star-forming regions by the James Webb Space Telescope, including a substantial number (42) of Jupiter Mass Binary Objects ('JuMBOs') in the Orion Nebula Cluster. The JuMBOs have much wider separations than other populations of substellar binaries, and their existence challenges conventional theories of substellar and planetary-mass object formation. Whilst several theories have been proposed to explain their formation, there has yet to be a study that determines whether they could survive the dynamical encounters prevalent within a dense star-forming region. We place a population of planet-planet binaries in N-body simulations of dense star-forming regions and calculate their binary fraction over time. We find that between 50-90 per cent of planet-planet binaries are destroyed on timescales of a few Myr, which implies that many more must form if we are to observe them in their current numbers. Furthermore, if the ONC was much more dense at formation, the initial separation distribution of the JuMBOs must have been even wider (and less similar to other substellar binaries) than the observed distribution.
+#### The JWST weather report from the nearest brown dwarfs II: Consistent variability mechanisms over 7 months revealed by 1-14 $μ$m NIRSpec + MIRI monitoring of WISE 1049AB
+ - **Authors:** Xueqing Chen, Beth A. Biller, Xianyu Tan, Johanna M. Vos, Yifan Zhou, Genaro Suárez, Allison M. McCarthy, Caroline V. Morley, Niall Whiteford, Trent J. Dupuy, Jacqueline Faherty, Ben J. Sutlieff, Natalia Oliveros-Gomez, Elena Manjavacas, Mary Anne Limbach, Elspeth K. H. Lee, Theodora Karalidi, Ian J.M. Crossfield, Pengyu Liu, Paul Molliere, Philip S. Muirhead, Thomas Henning, Gregory Mace, Nicolas Crouzet, Tiffany Kataria
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
+ - **Arxiv link:** https://arxiv.org/abs/2505.00794
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.00794
+
+ - **Abstract**
+ We present a new epoch of JWST spectroscopic variability monitoring of the benchmark binary brown dwarf WISE 1049AB, the closest, brightest brown dwarfs known. Our 8-hour MIRI low resolution spectroscopy (LRS) and 7-hour NIRSpec prism observations extended variability measurements for any brown dwarfs beyond 11 $\mu$m for the first time, reaching up to 14 $\mu$m. Combined with the previous epoch in 2023, they set the longest JWST weather monitoring baseline to date. We found that both WISE 1049AB show wavelength-dependent light curve behaviours. Using a robust k-means clustering algorithm, we identified several clusters of variability behaviours associated with three distinct pressure levels. By comparing to a general circulation model (GCM), we identified the possible mechanisms that drive the variability at these pressure levels: Patchy clouds rotating in and out of view likely shaped the dramatic light curves in the deepest layers between 1-2.5 $\mu$m, whereas hot spots arising from temperature / chemical variations of molecular species likely dominate the high-altitude levels between 2.5-3.6 $\mu$m and 4.3-8.5 $\mu$m. Small-grain silicates potentially contributed to the variability of WISE 1049A at 8.5-11 $\mu$m. While distinct atmospheric layers are governed by different mechanisms, we confirmed for the first time that each variability mechanism remains consistent within its layer over the long term. Future multi-period observations will further test the stability of variability mechanisms on this binary, and expanded JWST variability surveys across the L-T-Y sequence will allow us to trace and understand variability mechanisms across a wider population of brown dwarfs and planetary-mass objects.
+#### A Model of UV-Blue Absorbance in Bulk Liquid of Venusian Cloud Aerosols Is Consistent with Efficient Organic Absorbers at High Concentrations
+ - **Authors:** Jan Spacek, Yeon J. Lee, Paul B. Rimmer, Janusz J. Petkowski
+ - **Subjects:** Subjects:
+Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
+ - **Arxiv link:** https://arxiv.org/abs/2505.00880
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.00880
+
+ - **Abstract**
+ At visible wavelengths, Venus appears serene and pale-yellow, but since the 1920s, observers have noted high-contrast features in the ultraviolet. These features track the about 4-day superrotation of the upper cloud deck and vary widely over time and space. The identity of the UV absorber(s)-active between at least 280 and 500 nm-remains unknown, as no proposed candidate fully matches all observational data. From remote observations of Venus, and accounting for light scattering by sub-micrometer droplets, we modeled the 365-455 nm absorbance per cm of the bulk liquids forming Venus's clouds. Assuming a uniform distribution in mode 1 and 2 particles across a 6 km layer below the cloud top at 65 km, we constrain the bulk absorbance with a peak at A375 nm being 2942 per cm. This extremely high absorbance implies the presence of a highly efficient absorber, most likely conjugated organics, at relatively high concentration-e.g. about 25 g/L for porphyrin type pigments. Inorganic absorbers, with molar absorption coefficients typically in the range of 1,000-10,000 per M per cm, would either need to comprise a large portion of the aerosols or are simply not light absorbent enough, even if present in pure form. We emphasize that all candidate absorbers must be evaluated against Venus's reflectance curve using (i) known molar absorption coefficients, (ii) realistic atmospheric distributions, and (iii) appropriate particle size distributions. The upcoming Rocket Lab mission will test the hypothesis of organics in Venus's clouds.
+#### A Survey Of Model Fits to Brown Dwarf Spectra Through the L-T Sequence
+ - **Authors:** Savanah K. Turner, Denise C. Stephens, Conner B. Scoresby, Josh A. Miller
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
+ - **Arxiv link:** https://arxiv.org/abs/2505.00978
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.00978
+
+ - **Abstract**
+ We fit archival near-infrared spectra of 305 brown dwarfs with atmosphere models from the Sonora and Phoenix groups. Using the parameters of the best-fit models as estimates for the physical properties of the brown dwarfs in our sample, we have performed a survey of how brown dwarf atmospheres evolve with spectral type and temperature. We present the fit results and observed trends. We find that clouds have a more significant impact on near infrared spectra than disequilibrium chemistry, and that silicate clouds influence the near infrared spectrum through the late T types. We note where current atmosphere models are able to replicate the data and where the models and data conflict. We also categorize objects with similar spectral morphologies into families and discuss possible causes for their unique spectral traits. We identify two spectral families with morphologies that are likely indicative of binarity.
+#### Instrumentation prospects for rocky exoplanet atmospheres studies with high resolution spectroscopy
+ - **Authors:** Surangkhana Rukdee
+ - **Subjects:** Subjects:
+Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
+ - **Arxiv link:** https://arxiv.org/abs/2505.01102
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.01102
+
+ - **Abstract**
+ Studying the atmospheres of exoplanets is one of the most promising ways to learn about distant worlds beyond our solar system. The composition of an exoplanet's atmosphere can provide critical insights into its geology and potential habitability. For instance, the presence of certain molecules such as water vapor, oxygen, or methane have been proposed to indicate the possibility of life. From an observation point of view, over the past fifteen years, significant progress has been made in characterizing exoplanetary atmospheres. This work reviews recent developments in ground-based high-resolution spectroscopic instruments that make it possible to analyze distant atmospheres in great detail. High-resolution transmission spectroscopy, one of the most effective methods used, has examined the atmospheres of Jupiter-like and is pushing towards the smaller, sub-Neptunian exoplanets. Numerous molecules have been detected using this technique, including CO,H2O,TiO,HCN,CH4,NH3,C2H2,OH. We explore the intriguing possibilities that lie ahead for future ground-based instrumentation, particularly in the context of detecting biologically relevant molecules within Earth-analog exoplanetary atmospheres including molecular oxygen (O2). With detailed exposure time calculations for detecting O2 we find that at the same exposure time spectral resolution of 300,000 reaches higher significance compared to 100,000. The exposure time and therefore the needed number of transits is reduced by a factor of 4 in challenging haze and cloud scenarios.
+#### Redshift-space bispectrum in presence of massive neutrinos: A multipole expansion approach for Euclid
+ - **Authors:** Sourav Pal, Debanjan Sarkar, Rickmoy Samanta, Supratik Pal
+ - **Subjects:** Subjects:
+Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
+ - **Arxiv link:** https://arxiv.org/abs/2505.01270
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.01270
+
+ - **Abstract**
+ Massive neutrinos imprint distinctive signatures on the evolution of cosmic structures, notably suppressing small-scale clustering. We investigate the impact of massive neutrinos on the galaxy bispectrum in redshift-space, adopting a spherical harmonic multipole decomposition $B_L^m(k_1, \mu, t)$, that captures the full angular dependence. We develop an analytical and numerical framework incorporating neutrino-corrected perturbation theory kernels and redshift-space distortions. Our results demonstrate that the linear triangle configurations are particularly sensitive to massive neutrinos, with deviations reaching up to $\sim 2\%$ for a total mass $\sum m_\nu = 0.12\,\mathrm{eV}$. To assess detection prospects in galaxy surveys like \textit{Euclid}, we compute the signal-to-noise ratio (SNR) for individual multipoles, including the effects of Finger-of-God damping and shot noise. The neutrino-induced signatures in $B_0^0$ and $B_2^0$ are found to be detectable with SNR $\gtrsim 5$ across a range of configurations, even after accounting for small-scale suppression. Higher-order multipoles such as $B_2^1$ and $B_2^2$ are moderately sensitive, with SNR $\gtrsim$ ($2-3$) in squeezed limits, while hexadecapole moments are more suppressed but still exhibit measurable signals at high $k_1$. Additionally, the SNR generally increases with wave number $k_1$, particularly for squeezed and stretched triangles, suggesting that access to smaller scales significantly enhances detection this http URL study highlights the potential of the redshift-space bispectrum multipoles as sensitive probes of massive neutrinos, complementing traditional power spectrum analyses, and underscores the importance of angular information and higher-order statistics for galaxy surveys.
+#### Classifying Radio-Loud and Radio-Quiet Quasars With Novel PCA Based Regression Classifier
+ - **Authors:** Ramkrishna Joshi, Vivek Shinde
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2505.01335
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.01335
+
+ - **Abstract**
+ The problem of quasar classification comes in the class of highly imbalanced classification problems since Radio-loud (RL) quasars are rare and make up only about 10% of the quasar population. In this work, we use the Sloan Digital Sky Survey-DR3 dataset and introduce a PCA-based regression pipeline designed to maximize recall for rare classes in class-imbalanced astronomical data. We demonstrate an effective methodology to identify the key features of the dataset and apply Principal Component Analysis (PCA) for dimensionality reduction. For the PCA transformed SDSS-DR3 dataset, first two components account for the 97% of the observed variance. We perform classification of Radio-Loud (RL) and Radio-Quiet (RQ) quasars with Random Forest Classifier (RFC), novel PCA based balanced linear regression classifier (PBC), Random forest integrated with SMOTE classifier and XGBoost classifier with threshold tuning. RFC achieves an overall accuracy of 92% while PBC achieves an overall accuracy of 62%. XGBoost achieves an overall accuracy of 72% and SMOTE integrated RFC achieves an accuracy of 85%. Higher precision is obtained for RQ quasars in all classification methods. For the RL class, RFC achieves a recall of 0.04, XGBoost achieves a recall of 0.39, SMOTE integrated RFC achieves a recall of 0.25 and PBC achieves a recall of 0.52 attributed to the balanced logistic regression. RFC and PBC achieve F1 score of 0.08 and 0.19 respectively for RL while XGBoost achieves an improved F1 score of 0.22 but at the cost of reduced recall of the RL class. SMOTE integrated RFC achieves a better F1 score of 0.21 over RFC and PBC. Overall results of classifiers point to extreme class imbalance between RQ and RL classes in the data set.
+#### Probing the Cores of Subdwarf B Stars: How do They Compare to Cores in Helium Core-Burning Red Giants?
+ - **Authors:** Margarida S. Cunha, Juliana Amaral, Sofia Avelino, Anselmo Falorca, Yuri Damasceno, Pedro Avelino
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2505.01381
+
+ - **Pdf link:** https://arxiv.org/pdf/2505.01381
+
+ - **Abstract**
+ The mixing of material from stellar convective cores into their adjacent radiative layers has been a matter of long-standing debate. Pulsating subdwarf B stars offer excellent conditions to advance our understanding of this problem. In this work we use a model-independent approach to infer information about the cores of three subdwarf B stars and compare it with similar inferences from earlier analysis of red giants in the helium core-burning phase. This is achieved by fitting an analytical description of the gravity-mode pulsation periods to pulsation data collected by the Kepler satellite. From the fits we infer the reduced asymptotic period spacings and the amplitude and position of sharp structural variations associated with chemical discontinuities in the stellar interiors. Our results indicate the presence of sharp structural variations with similar properties in all three stars, located near the edge of the gravity-mode propagation cavity and likely associated with the C-O/He transition. We find that these structural variations differ systematically from those of helium core-burning red giant stars, having larger amplitudes and being located at a larger buoyancy radius. This suggests that chemical mixing beyond the adiabatically stratified core into the radiatively stratified layers may be more extensive in subdwarf B stars than in helium core-burning red giants. Alternatively, the stratification of the mixing region beyond the adiabatically stratified core may differ significantly between the two types of stars. The model-independent constraints set on the structural variations inside these three stars are the first of a kind and will be key to enhance the modelling of layers adjacent to stellar convective cores and to test non-canonical stellar evolution channels leading to the formation of hot subdwarf stars.
+
+
+by olozhika (Xing Yuchen). 
+
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+2025-05-05