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Physics Astrophysics

astro-ph Watch Astrophysics

Friday 10 October

Instrumentation and Methods for Astrophysics

deep-REMAP: Probabilistic Parameterization of Stellar Spectra Using Regularized Multi-Task Learning

Sankalp Gilda

In the era of exploding survey volumes, traditional methods of spectroscopic analysis are being pushed to their limits. In response, we develop deep-REMAP, a novel deep learning framework that utilizes a regularized, multi-task approach to predict stellar atmospheric parameters from observed spectra. We train a deep convolutional neural network on the PHOENIX synthetic spectral library and use transfer learning to fine-tune the model on a small subset of observed FGK dwarf spectra from the MARVELS survey. We then apply the model to 732 uncharacterized FGK giant candidates from the same survey. When validated on 30 MARVELS calibration stars, deep-REMAP accurately recovers the effective temperature ($T_{\rm{eff}}$), surface gravity ($\log \rm{g}$), and metallicity ([Fe/H]), achieving a precision of, for instance, approximately 75 K in $T_{\rm{eff}}$. By combining an asymmetric loss function with an embedding loss, our regression-as-classification framework is interpretable, robust to parameter imbalances, and capable of capturing non-Gaussian uncertainties. While developed for MARVELS, the deep-REMAP framework is extensible to other surveys and synthetic libraries, demonstrating a powerful and automated pathway for stellar characterization.
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Earth and Planetary Astrophysics

Probing the geological setting of exoplanets through atmospheric analysis: using Mars as a test case

Monica Rainer, Evandro Balbi, Francesco Borsa et al. (+3 more)

One of the frontier research fields of exoplanetary science is the study of the composition and variability of exoplanetary atmospheres. This field is now moving from the gas giant planets towards the smaller and colder telluric planets, and future instruments like ANDES will focus on the observations of the atmosphere of telluric planets in the habitable zone in reflected light. These future observations will possibly find variable signals due to the view of different hemispheres of the planet. Particularly, the strength of the signal may be linked to the thickness of the atmospheric layer probed, and therefore to the average altitude variations of the planetary surface, that are related to the global geodynamic evolution of the planet. To better prepare for the interpretation and exploitation of these future data, we used Mars as a Solar System analog of a spatially resolved telluric exoplanet. We observed the reflected light of Mars with the high-resolution near-infrared (NIR) spectrograph GIANO-B (widely used in exoplanetary atmospheric studies) during a 3 month period: we studied the spatial and temporal variations of the Martian CO2 signal using the least-squared deconvolution technique (LSD), to mimic as closely as possible the standard exoplanetary atmospheric analysis. We linked the variations found to the well-known Martian geological surface characteristics: we found a clear dependence of the strength of the CO2 signal with the thickness of the Martian atmospheric layer by comparing the retrieved CO2 signal with the altitudes of our pointings. The proposed strategy is promising: it proved to be effective on Mars and may shed light on the variations in the strength of atmospheric signal of telluric exoplanets.
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All authors Monica Rainer, Evandro Balbi, Francesco Borsa, Paola Cianfarra, Avet Harutyunyan, Silvano Tosi

Cosmology and Nongalactic Astrophysics

Effect of stochastic kicks on primordial black hole abundance and mass via the compaction function

Sami Raatikainen, Syksy Rasanen and Eemeli Tomberg

We study stochastic effects in viable ultra-slow-roll inflation models that produce primordial black holes. We consider asteroid, solar, and supermassive black hole seed masses. In each case, we simulate $10^8$ patches of the universe that may collapse into PBHs. In every patch, we follow $4\times10^4$ momentum shells to construct its spherically symmetric profile from first principles, without introducing a window function. We include the effects of critical collapse and the radiation era transfer function. The resulting compaction function profiles are very spiky due to stochastic kicks. This can enhance the PBH abundance by up to 36 orders of magnitude, depending on the mass range and collapse criterion. The PBH mass function shifts to higher masses and widens significantly. These changes may have a large effect on observational constraints of PBHs and make it possible to generate PBHs with a smaller amplitude of the power spectrum. However, convergence issues for the mass function remain. The results call for redoing collapse simulations to determine the collapse criterion for spiky profiles.
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High Energy Astrophysical Phenomena

Light Travel Time Effects in Kilonova Models

F. McNeill, S. A. Sim, C. E. Collins et al. (+4 more)

The extremely rapid evolution of kilonovae results in spectra that change on an hourly basis. These spectra are key to understanding the processes occurring within the event, but this rapid evolution is an unfamiliar domain compared to other explosive transient events, such as supernovae. In particular, the most obvious P Cygni feature in the spectra of AT2017gfo – commonly attributed to strontium – possesses an emission component that emerges after, and ultimately outlives, its associated absorption dip. This delay is theorised to arise from reverberation effects, wherein photons emitted earlier in the kilonova's evolution are scattered before reaching the observer, causing them to be detected at later times. We aim to examine how the finite speed of light – and therefore the light travel time to an observer – contributes to the shape and evolution of spectral features in kilonovae. Using a simple model, and tracking the length of the journey photons undertake to an observer, we are able to test the necessity of accounting for this time delay effect when modelling kilonovae. In periods where the photospheric temperature is rapidly evolving, we show spectra synthesised using a time independent approach are visually distinct from those where these time delay effects are accounted for. Therefore, in rapidly evolving events such as kilonovae, time dependence must be taken into account.
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All authors F. McNeill, S. A. Sim, C. E. Collins, L. J. Shingles, R. Damgaard, A. Sneppen, J. H. Gillanders

Cosmology and Nongalactic Astrophysics

Hubble Constant and Mass Determination of Centaurus A & M83 from TRGB Distances

Adrian Faucher, David Benisty and David F. Mota

An independent determination of the Hubble constant is crucial given the persistent tension between early- and late-Universe measurements. In this study, we analyze the dynamics of the Centaurus~A (CenA) and M83 galaxies, along with their associated dwarf companions identified via Tip of the Red Giant Branch (TRGB) distance measurements, to constrain both the group mass and the local value of the Hubble constant ($H_0$). By examining the motions of these galaxies relative to the system's barycenter, we apply both the minor and major infall models, which provide bounds on the true radial velocity dispersion. From the overlap of these approaches, we obtain a virial mass estimate of $(7.3 \pm 2.0) \times 10^{12}\,M_{\odot}$ and a Hubble flow-based mass of $(2.6 \pm 1.4) \times 10^{12}\,M_{\odot}$. Modeling the cold Hubble flow around the group center of mass yields a corresponding Hubble constant of $(64.0 \pm 4.6)\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$. These results offer an independent, dynamically motivated constraint on the local value of $H_0$, explicitly accounting for the impact of peculiar velocities in the nearby Universe. We also discuss the $\sim 2\sigma$ tension between the virial and Hubble flow-based mass estimates, which likely arises from the proximity of M83 to the velocity surface, breaking the assumptions of the Hubble flow model. While the Hubble flow fit emphasizes galaxies that follow smooth expansion on the lower branch of the velocity-distance relation, the virial mass estimate is in good agreement with the group mass derived from the $K$-band luminosity of its brightest members and from projected mass methods.
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Solar and Stellar Astrophysics

The age and metallicity dependence of the near-infrared absolute magnitude and colour of red clump stars

Hiroki Onozato, Yoshifusa Ita and Yoshikazu Nakada

Understanding the age and metallicity dependence of the absolute magnitude and colour of red clump (RC) stars is crucial for validating the accuracy of stellar evolution models and enhancing their reliability as a standard candle. However, this dependence has previously been investigated in the near-infrared across multiple bands only for -1.05 $\leq$ [Fe/H] $\leq$ 0.40, a range accessible through the star clusters in the Large Magellanic Cloud. Therefore, we used star clusters in the Small Magellanic Cloud and the Milky Way Galaxy to investigate the age and metallicity dependence of the absolute magnitude and colour of RC stars in the near-infrared for a broader parameter space (0.45 $\leq$ Age (Gyr) $\leq$ 10.5, -1.65 $\leq$ [Fe/H] $\leq$ 0.32). Comparison of our results with three isochronous models BaSTI, PARSEC, and MIST reveals that the age dependence of the absolute magnitude for young RC stars aligns well with theoretical predictions, within the fitting errors of the multiple regression analysis. Additionally, the observed colour shows good agreement with the theoretical models. Notably, the $J - K_{S}$ colour, which spans a wide parameter space, reproduces the distribution expected from the theoretical model.
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Solar and Stellar Astrophysics

A systematic search for orbital periods of polars with TESS. Methods, detection limits, and results

Santiago Hernández-Díaz, Beate Stelzer, Axel Schwope et al. (+1 more)

Context. Determining the orbital periods of cataclysmic variable stars (CVs) is essential for confirming candidates and for the understanding of their evolutionary state. The Transiting Exoplanet Survey Satellite (TESS) provides month-long photometric data across nearly the entire sky that can be used to search for periodic variability in such systems. Aims. This study aims to identify and confirm the orbital periods for members of a recent compilation of magnetic CVs (known as polars) using TESS light curves. In addition, we set out to investigate their reliability, and hence the relevance of TESS for variability studies of CVs. Results. Ninety-five of the 217 polars in our sample have pipeline-produced TESS two-minute cadence light curves available. The results from our period search are overall in good agreement with the previously reported values. Out of the 95 analysed systems, 85 exhibit periods consistent with the literature values. Among the remaining ten objects, four are asynchronous polars, where TESS light curves resolve the orbital period, the white dwarf's spin period, and additional beat frequencies. For four systems, the periods detected from the TESS data differ from those previously reported. For two systems, a period detection was not possible. Our analysis of the flattened TESS light curves reveals a positive correlation between noise levels and TESS magnitude. Our noise level estimates resemble the rmsCDPP, a measure of white noise provided with the TESS pipeline products. However, our values for the noise level are systematically higher than the rmsCDPP indicating red noise and high-frequency signals hidden in the flattened light curves. Additionally, we present a statistical methodology to assess the reliability of period detections in TESS light curves. We find that for TESS magnitudes $\gtrsim$ 17, period detections become increasingly unreliable.
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All authors Santiago Hernández-Díaz, Beate Stelzer, Axel Schwope, Daniela Muñoz-Giraldo

Cosmology and Nongalactic Astrophysics

Euclid preparation. XCVI. Cosmology Likelihood for Observables in Euclid (CLOE). 3. Inference and Forecasts

Euclid Collaboration: G. Cañas-Herrera, L. W. K. Goh, L. Blot et al. (+336 more)

The Euclid mission aims to measure the positions, shapes, and redshifts of over a billion galaxies to provide unprecedented constraints on the nature of dark matter and dark energy. Achieving this goal requires a continuous reassessment of the mission's scientific performance, particularly in terms of its ability to constrain cosmological parameters, as our understanding of how to model large-scale structure observables improves. In this study, we present the first scientific forecasts using CLOE (Cosmology Likelihood for Observables in Euclid), a dedicated Euclid cosmological pipeline developed to support this endeavour. Using advanced Bayesian inference techniques applied to synthetic Euclid-like data, we sample the posterior distribution of cosmological and nuisance parameters across a variety of cosmological models and Euclid primary probes: cosmic shear, angular photometric galaxy clustering, galaxy-galaxy lensing, and spectroscopic galaxy clustering. We validate the capability of CLOE to produce reliable cosmological forecasts, showcasing Euclid's potential to achieve a figure of merit for the dark energy parameters $w_0$ and $w_a$ exceeding 400 when combining all primary probes. Furthermore, we illustrate the behaviour of the posterior probability distribution of the parameters of interest given different priors and scale cuts. Finally, we emphasise the importance of addressing computational challenges, proposing further exploration of innovative data science techniques to efficiently navigate the Euclid high-dimensional parameter space in upcoming cosmological data releases.
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All authors Euclid Collaboration: G. Cañas-Herrera, L. W. K. Goh, L. Blot, M. Bonici, S. Camera, V. F. Cardone, P. Carrilho, S. Casas, S. Davini, S. Di Domizio, S. Farrens, S. Gouyou Beauchamps, S. Ilić, S. Joudaki, F. Keil, A. M. C. Le Brun, M. Martinelli, C. Moretti, V. Pettorino, A. Pezzotta, Z. Sakr, A. G. Sánchez, D. Sciotti, K. Tanidis, I. Tutusaus, V. Ajani, M. Crocce, A. Fumagalli, C. Giocoli, L. Legrand, M. Lembo, G. F. Lesci, D. Navarro Girones, A. Nouri-Zonoz, S. Pamuk, A. Pourtsidou, M. Tsedrik, J. Bel, C. Carbone, J. Claramunt Gonzalez, C. A. J. Duncan, M. Kilbinger, A. Porredon, D. Sapone, E. Sellentin, P. L. Taylor, N. Tessore, B. Altieri, A. Amara, L. Amendola, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, S. Bardelli, R. Bender, A. Biviano, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, V. Capobianco, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, S. de la Torre, G. De Lucia, A. M. Di Giorgio, H. Dole, F. Dubath, X. Dupac, S. Dusini, S. Escoffier, M. Farina, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, N. Fourmanoit, M. Frailis, E. Franceschi, S. Galeotta, K. George, W. Gillard, B. Gillis, P. Gómez-Alvarez, J. Gracia-Carpio, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. Hook, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, K. Kuijken, M. Kümmel, M. Kunz, H. Kurki-Suonio, O. Lahav, R. Laureijs, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, H. J. McCracken, E. Medinaceli, M. Melchior, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, B. Sartoris, J. A. Schewtschenko, P. Schneider, T. Schrabback, A. Secroun, E. Sefusatti, G. Seidel, M. Seiffert, S. Serrano, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J. Steinwagner, P. Tallada-Crespí, D. Tavagnacco, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, E. Zucca, M. Ballardini, M. Bolzonella, A. Boucaud, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, P. Casenove, D. Di Ferdinando, J. A. Escartin Vigo, L. Gabarra, S. Matthew, N. Mauri, R. B. Metcalf, M. Pöntinen, C. Porciani, V. Scottez, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, S. Alvi, I. T. Andika, R. E. Angulo, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, A. Balaguera-Antolinez, M. Bethermin, A. Blanchard, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, A. Cappi, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, S. Contarini, A. R. Cooray, O. Cucciati, F. De Paolis, G. Desprez, A. Díaz-Sánchez, J. M. Diego, P. Dimauro, A. Enia, Y. Fang, A. G. Ferrari, P. G. Ferreira, A. Finoguenov, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, R. Gavazzi, E. Gaztanaga, F. Giacomini, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, S. Hemmati, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, C. C. Kirkpatrick, S. Kruk, F. Lacasa, M. Lattanzi, J. Le Graet, F. Lepori, G. Leroy, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, S. J. Liu, A. Loureiro, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, R. Maoli, J. Martín-Fleitas, C. J. A. P. Martins, L. Maurin, M. Migliaccio, M. Miluzio, P. Monaco, A. Montoro, G. Morgante, C. Murray, S. Nadathur, K. Naidoo, A. Navarro-Alsina, S. Nesseris, L. Pagano, F. Passalacqua, K. Paterson, L. Patrizii, A. Pisani, D. Potter, S. Quai, M. Radovich, P. Reimberg, I. Risso, G. Rodighiero, S. Sacquegna, M. Sahlén, E. Sarpa, J. Schaye, A. Schneider, M. Sereno, A. Silvestri, L. C. Smith, J. Stadel, C. Tao, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, F. Vernizzi, G. Verza, N. A. Walton

Cosmology and Nongalactic Astrophysics

Detecting dark matter substructure with lensed quasars in optical bands

Jianxiang Liu, Kai Liao and Yan Gong

Flux ratios of multiple images in strong gravitational lensing systems provide a powerful probe of dark matter substructure. Optical flux ratios of lensed quasars are typically affected by stellar microlensing, and thus studies of dark matter substructure often rely on emission regions that are sufficiently extended to avoid microlensing effects. To expand the accessible wavelength range for studying dark matter substructure through flux ratios and to reduce reliance on specific instruments, we confront the challenges posed by microlensing and propose a method to detect dark matter substructure using optical flux ratios of lensed quasars. We select 100 strong lensing systems consisting of 90 doubles and 10 quads to represent the overall population and adopt the Kolmogorov–Smirnov (KS) test as our statistical method. By introducing different types of dark matter substructure into these strong lensing systems, we demonstrate that using quads alone provides the strongest constraints on dark matter and that several tens to a few hundred independent flux ratio measurements from quads can be used to study the properties of dark matter substructure and place constraints on dark matter parameters. Furthermore, we suggest that the use of multi-band flux ratios can substantially reduce the required number of quads. Such sample sizes will be readily available from ongoing and upcoming wide-field surveys.
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Cosmology and Nongalactic Astrophysics

Euclid preparation. XCVIII. Cosmology Likelihood for Observables in Euclid (CLOE). 5: Extensions beyond the standard modelling of theoretical probes and systematic effects

Euclid Collaboration: L. W. K. Goh, A. Nouri-Zonoz, S. Pamuk et al. (+300 more)

Euclid is expected to establish new state-of-the-art constraints on extensions beyond the standard LCDM cosmological model by measuring the positions and shapes of billions of galaxies. Specifically, its goal is to shed light on the nature of dark matter and dark energy. Achieving this requires developing and validating advanced statistical tools and theoretical prediction software capable of testing extensions of the LCDM model. In this work, we describe how the Euclid likelihood pipeline, Cosmology Likelihood for Observables in Euclid (CLOE), has been extended to accommodate alternative cosmological models and to refine the theoretical modelling of Euclid primary probes. In particular, we detail modifications made to CLOE to incorporate the magnification bias term into the spectroscopic two-point correlation function of galaxy clustering. Additionally, we explain the adaptations made to CLOE's implementation of Euclid primary photometric probes to account for massive neutrinos and modified gravity extensions. Finally, we present the validation of these CLOE modifications through dedicated forecasts on synthetic Euclid-like data by sampling the full posterior distribution and comparing with the results of previous literature. In conclusion, we have identified in this work several functionalities with regards to beyond-LCDM modelling that could be further improved within CLOE, and outline potential research directions to enhance pipeline efficiency and flexibility through novel inference and machine learning techniques.
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All authors Euclid Collaboration: L. W. K. Goh, A. Nouri-Zonoz, S. Pamuk, M. Ballardini, B. Bose, G. Cañas-Herrera, S. Casas, G. Franco-Abellán, S. Ilić, F. Keil, M. Kunz, A. M. C. Le Brun, F. Lepori, M. Martinelli, Z. Sakr, F. Sorrenti, E. M. Teixeira, I. Tutusaus, L. Blot, M. Bonici, C. Bonvin, S. Camera, V. F. Cardone, P. Carrilho, S. Di Domizio, R. Durrer, S. Farrens, S. Gouyou Beauchamps, S. Joudaki, C. Moretti, A. Pezzotta, A. G. Sánchez, D. Sciotti, K. Tanidis, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, D. Bagot, M. Baldi, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, V. Capobianco, C. Carbone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, S. de la Torre, G. De Lucia, H. Dole, M. Douspis, F. Dubath, X. Dupac, S. Escoffier, M. Farina, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, L. Guzzo, H. Hoekstra, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. Kümmel, H. Kurki-Suonio, O. Lahav, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, D. Sapone, B. Sartoris, J. A. Schewtschenko, T. Schrabback, A. Secroun, E. Sefusatti, G. Seidel, M. Seiffert, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, A. Tsyganov, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, E. Zucca, M. Bolzonella, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, D. Di Ferdinando, J. A. Escartin Vigo, L. Gabarra, W. G. Hartley, J. Martín-Fleitas, M. Maturi, N. Mauri, R. B. Metcalf, M. Pöntinen, C. Porciani, I. Risso, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, A. Balaguera-Antolinez, D. Bertacca, M. Bethermin, A. Blanchard, H. Böhringer, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, S. Contarini, A. R. Cooray, O. Cucciati, S. Davini, F. De Paolis, G. Desprez, A. Díaz-Sánchez, J. J. Diaz, J. M. Diego, P. Dimauro, A. Enia, Y. Fang, A. G. Ferrari, P. G. Ferreira, A. Finoguenov, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, A. Gruppuso, M. Guidi, C. M. Gutierrez, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, C. C. Kirkpatrick, S. Kruk, F. Lacasa, M. Lattanzi, V. Le Brun, L. Legrand, M. Lembo, G. Leroy, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, S. J. Liu, A. Loureiro, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, M. Miluzio, P. Monaco, G. Morgante, S. Nadathur, K. Naidoo, A. Navarro-Alsina, S. Nesseris, L. Pagano, F. Passalacqua, K. Paterson, L. Patrizii, D. Potter, A. Pourtsidou, S. Quai, M. Radovich, P.-F. Rocci, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, J. Schaye, A. Schneider, M. Schultheis, E. Sellentin, C. Tao, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, F. Vernizzi, G. Verza, N. A. Walton

Cosmology and Nongalactic Astrophysics

Euclid preparation XCVII. Cosmology Likelihood for Observables in Euclid (CLOE). 4: Validation and performance

Euclid Collaboration: M. Martinelli, A. Pezzotta, D. Sciotti et al. (+333 more)

The Euclid satellite will provide data on the clustering of galaxies and on the distortion of their measured shapes, which can be used to constrain and test the cosmological model. However, the increase in precision places strong requirements on the accuracy of the theoretical modelling for the observables and of the full analysis pipeline. In this paper, we investigate the accuracy of the calculations performed by the Cosmology Likelihood for Observables in Euclid (CLOE), a software able to handle both the modelling of observables and their fit against observational data for both the photometric and spectroscopic surveys of Euclid, by comparing the output of CLOE with external codes used as benchmark. We perform such a comparison on the quantities entering the calculations of the observables, as well as on the final outputs of these calculations. Our results highlight the high accuracy of CLOE when comparing its calculation against external codes for Euclid observables on an extended range of operative cases. In particular, all the summary statistics of interest always differ less than $0.1\,\sigma$ from the chosen benchmark, and CLOE predictions are statistically compatible with simulated data obtained from benchmark codes. The same holds for the comparison of correlation function in configuration space for spectroscopic and photometric observables.
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All authors Euclid Collaboration: M. Martinelli, A. Pezzotta, D. Sciotti, L. Blot, M. Bonici, S. Camera, G. Cañas-Herrera, V. F. Cardone, P. Carrilho, S. Casas, S. Davini, S. Di Domizio, S. Farrens, L. W. K. Goh, S. Gouyou Beauchamps, S. Ilić, S. Joudaki, F. Keil, A. M. C. Le Brun, C. Moretti, V. Pettorino, A. G. Sánchez, Z. Sakr, K. Tanidis, I. Tutusaus, V. Ajani, M. Crocce, C. Giocoli, L. Legrand, M. Lembo, G. F. Lesci, D. Navarro Girones, A. Nouri-Zonoz, S. Pamuk, M. Tsedrik, J. Bel, C. Carbone, C. A. J. Duncan, M. Kilbinger, F. Lacasa, M. Lattanzi, D. Sapone, E. Sellentin, P. L. Taylor, N. Aghanim, B. Altieri, L. Amendola, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, R. Bender, A. Biviano, A. Bonchi, D. Bonino, E. Branchini, M. Brescia, J. Brinchmann, V. Capobianco, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, H. M. Courtois, A. Da Silva, H. Degaudenzi, S. de la Torre, G. De Lucia, A. M. Di Giorgio, H. Dole, F. Dubath, X. Dupac, S. Dusini, A. Ealet, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, W. Gillard, B. Gillis, J. Gracia-Carpio, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, H. Hoekstra, W. Holmes, F. Hormuth, A. Hornstrup, P. Hudelot, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, K. Kuijken, M. Kümmel, M. Kunz, H. Kurki-Suonio, P. Liebing, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, K. Markovic, N. Martinet, F. Marulli, R. Massey, S. Maurogordato, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, S. Pires, G. Polenta, M. Poncet, L. A. Popa, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, B. Sartoris, J. A. Schewtschenko, P. Schneider, T. Schrabback, A. Secroun, E. Sefusatti, G. Seidel, M. Seiffert, S. Serrano, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J. Steinwagner, P. Tallada-Crespí, D. Tavagnacco, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, E. Zucca, V. Allevato, M. Ballardini, M. Bolzonella, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, D. Di Ferdinando, J. A. Escartin Vigo, L. Gabarra, J. Martín-Fleitas, S. Matthew, N. Mauri, R. B. Metcalf, M. Pöntinen, C. Porciani, I. Risso, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, S. Alvi, I. T. Andika, R. E. Angulo, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, A. Balaguera-Antolinez, M. Bethermin, A. Blanchard, H. Böhringer, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, A. Cappi, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, A. R. Cooray, O. Cucciati, F. De Paolis, G. Desprez, A. Díaz-Sánchez, J. J. Diaz, J. M. Diego, P. Dimauro, A. Enia, Y. Fang, A. G. Ferrari, P. G. Ferreira, A. Finoguenov, A. Fontana, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, A. Gruppuso, M. Guidi, C. M. Gutierrez, A. Hall, S. Hemmati, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, C. C. Kirkpatrick, S. Kruk, J. Le Graet, F. Lepori, G. Leroy, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, S. J. Liu, A. Loureiro, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, M. Migliaccio, M. Miluzio, P. Monaco, G. Morgante, S. Nadathur, K. Naidoo, P. Natoli, A. Navarro-Alsina, S. Nesseris, L. Pagano, F. Passalacqua, K. Paterson, L. Patrizii, A. Pisani, D. Potter, S. Quai, M. Radovich, P.-F. Rocci, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, A. Schneider, A. Shulevski, A. Silvestri, L. C. Smith, J. Stadel, C. Tao, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, F. Vernizzi, G. Verza, P. Vielzeuf, N. A. Walton

Solar and Stellar Astrophysics

Magnetohydrodynamic shallow water equations with the alpha effect: Rossby-dynamo waves in solar–stellar tachoclines

T. V. Zaqarashvili, M. Dikpati and P. A. Gilman

The activity of Sun-like stars is governed by the magnetic field, which is believed to be generated in a thin layer between convective and radiative envelopes. The dynamo layer, also called the tachocline, permits the existence of Rossby waves (r-modes) described by magnetohydrodynamic shallow water models, which may lead to short-term cycles in stellar activity. Convective cells penetrate into the layer creating an overshoot upper part, where they transport an additional energy for vigorous activity. The aim of this paper is to study the influence of overshooting convection on the dynamics of Rossby waves in the tachoclines of Sun-like stars. Here we write the magnetohydrodynamic shallow water equations with the effect of the penetrative convection and study the dynamics of wave modes in the layer. The formalism leads to the excitation of new oscillation modes connected with the dynamo coefficient, alpha, causing periodic modulations of all parameters in the tachocline. The modes are coupled with the Rossby waves resulting mutual exchange of convective and rotation energies. The timescales of Rossby-dynamo waves, for certain parameters, correspond to Schwabe (11 years) and Rieger (150-170 days) cycles as observed in solar activity. The waves provide a new paradigm for internal magnetism and may drive the dynamos of Sun-like stars. Theoretical properties of the waves and observations can be used for magneto-seismological sounding of stellar interiors.
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High Energy Astrophysical Phenomena · Cross-listed from physics.plasm-ph

Statistics of Current and Vorticity Structures in Relativistic Turbulence

Zachary Davis, Luca Comisso, Colby Haggerty et al. (+1 more)

Coherent structures created through turbulent cascades play a key role in energy dissipation and particle acceleration. In this work, we investigate both current and vorticity sheets in 3D particle-in-cell simulations of decaying relativistic turbulence in pair plasma by training a self-organizing map to recognize these structures. We subsequently carry out an extensive statistical analysis to reveal their geometric and structural properties. This analysis is systematically applied across a range of magnetizations ($\sigma$) and fluctuating-to-mean magnetic field strengths ($\delta B_0/B_0$) to assess how these parameters influence the resulting structures. We find that the structures' geometric properties form power-law distributions in their probability density functions (PDFs), with the exception of the structure width, which generally exhibits an exponential distribution peaking around 2 electron skin depths. The measurements show weak dependence on $\sigma$ but a strong dependence on $\delta B_0/B_0$. Finally, we investigate the spatial relationship between current sheets and vorticity sheets. We find that most current sheets are directly associated with at least one vorticity sheet neighbor and are often situated between two vorticity sheets. These findings provide a detailed statistical framework for understanding the formation and organization of coherent structures in relativistic magnetized turbulence, allowing for their incorporation into updated theoretical models for structure-based energy dissipation and particle acceleration processes crucial for interpreting high-energy astrophysical observations.
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All authors Zachary Davis, Luca Comisso, Colby Haggerty, Joonas Nättilä

Instrumentation and Methods for Astrophysics

Identification of molecular line emission using Convolutional Neural Networks

Nina Kessler, Timea Csengeri, David Cornu et al. (+2 more)

Complex organic molecules (COMs) are observed to be abundant in various astrophysical environments, in particular toward star forming regions they are observed both toward protostellar envelopes as well as shocked regions. Emission spectrum especially of heavier COMs may consists of up to hundreds of lines, where line blending hinders the analysis. However, identifying the molecular composition of the gas leading to the observed millimeter spectra is the first step toward a quantitative analysis. We develop a new method based on supervised machine learning to recognize spectroscopic features of the rotational spectrum of molecules in the 3mm atmospheric transmission band for a list of species including COMs with the aim to obtain a detection probability. We used local thermodynamic equilibrium (LTE) modeling to build a large set of synthetic spectra of 20 molecular species including COMs with a range of physical conditions typical for star forming regions. We successfully designed and trained a Convolutional Neural Network (CNN) that provides detection probabilities of individual species in the spectra. We demonstrate that the produced CNN-model has a robust performance to detect spectroscopic signatures from these species in synthetic spectra. We evaluate its ability to detect molecules according to the noise level, frequency coverage, and line-richness, and also test its performance for incomplete frequency coverage with high detection probabilities for the tested parameter space, and no false predictions. Ultimately, we apply the CNN-model to obtain predictions on observational data from the literature toward line-rich hot-core like sources, where detection probabilities remain reasonable with no false detection. We prove the use of CNNs facilitating the analysis of complex millimeter spectra both on synthetic spectra as well as first tests on observational data.
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All authors Nina Kessler, Timea Csengeri, David Cornu, Sylvain Bontemps, Laure Bouscasse

Cosmology and Nongalactic Astrophysics

Cosmology Likelihood for Observables in \Euclid (CLOE). 1. Theoretical recipe

Euclid Collaboration: V. F. Cardone, S. Joudaki, L. Blot et al. (+322 more)

As the statistical precision of cosmological measurements increases, the accuracy of the theoretical description of these measurements needs to increase correspondingly in order to infer the underlying cosmology that governs the Universe. To this end, we have created the Cosmology Likelihood for Observables in Euclid (CLOE), which is a novel cosmological parameter inference pipeline developed within the Euclid Consortium to translate measurements and covariances into cosmological parameter constraints. In this first in a series of six papers, we describe the theoretical recipe of this code for the Euclid primary probes. These probes are composed of the photometric 3x2pt observables of cosmic shear, galaxy-galaxy lensing, and galaxy clustering, along with spectroscopic galaxy clustering. We provide this description in both Fourier and configuration space for standard and extended summary statistics, including the wide range of systematic uncertainties that affect them. This includes systematic uncertainties such as intrinsic galaxy alignments, baryonic feedback, photometric and spectroscopic redshift uncertainties, shear calibration uncertainties, sample impurities, photometric and spectroscopic galaxy biases, as well as magnification bias. The theoretical descriptions are further able to accommodate both Gaussian and non-Gaussian likelihoods and extended cosmologies with non-zero curvature, massive neutrinos, evolving dark energy, and simple forms of modified gravity. These theoretical descriptions that underpin CLOE will form a crucial component in revealing the true nature of the Universe with next-generation cosmological surveys such as Euclid.
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All authors Euclid Collaboration: V. F. Cardone, S. Joudaki, L. Blot, M. Bonici, S. Camera, G. Cañas-Herrera, P. Carrilho, S. Casas, S. Davini, S. Di Domizio, S. Farrens, L. W. K. Goh, S. Gouyou Beauchamps, S. Ilić, F. Keil, A. M. C. Le Brun, M. Martinelli, C. Moretti, V. Pettorino, A. Pezzotta, A. G. Sánchez, Z. Sakr, D. Sciotti, K. Tanidis, I. Tutusaus, V. Ajani, M. Crocce, C. Giocoli, L. Legrand, M. Lembo, G. F. Lesci, D. Navarro Girones, A. Nouri-Zonoz, S. Pamuk, M. Tsedrik, J. Bel, C. Carbone, C. A. J. Duncan, M. Kilbinger, F. Lacasa, M. Lattanzi, D. Sapone, E. Sellentin, P. L. Taylor, N. Aghanim, B. Altieri, L. Amendola, S. Andreon, N. Auricchio, H. Aussel, C. Baccigalupi, M. Baldi, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, J. Brinchmann, V. Capobianco, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, A. M. Di Giorgio, M. Douspis, F. Dubath, X. Dupac, S. Dusini, A. Ealet, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, P. Fosalba, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, B. Gillis, P. Gómez-Alvarez, J. Gracia-Carpio, B. R. Granett, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, O. Lahav, P. Liebing, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, N. Martinet, F. Marulli, R. Massey, S. Maurogordato, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, G. D. Racca, F. Raison, R. Rebolo, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, B. Sartoris, R. Scaramella, J. A. Schewtschenko, P. Schneider, T. Schrabback, A. Secroun, E. Sefusatti, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, G. Zamorani, F. M. Zerbi, E. Zucca, V. Allevato, M. Ballardini, M. Bolzonella, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, D. Di Ferdinando, J. A. Escartin Vigo, L. Gabarra, W. G. Hartley, J. Martín-Fleitas, S. Matthew, M. Maturi, N. Mauri, R. B. Metcalf, M. Pöntinen, C. Porciani, I. Risso, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, S. Alvi, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, A. Balaguera-Antolinez, M. Bethermin, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, S. Contarini, A. R. Cooray, O. Cucciati, F. De Paolis, G. Desprez, A. Díaz-Sánchez, J. J. Diaz, J. M. Diego, P. Dimauro, A. Enia, Y. Fang, A. G. Ferrari, P. G. Ferreira, A. Finoguenov, A. Fontana, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, A. Gruppuso, M. Guidi, C. M. Gutierrez, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, C. C. Kirkpatrick, S. Kruk, F. Lepori, G. Leroy, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, S. J. Liu, A. Loureiro, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, M. Migliaccio, M. Miluzio, P. Monaco, G. Morgante, S. Nadathur, K. Naidoo, A. Navarro-Alsina, S. Nesseris, L. Pagano, F. Passalacqua, K. Paterson, L. Patrizii, A. Pisani, D. Potter, S. Quai, M. Radovich, P. Reimberg, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, J. Schaye, A. Schneider, M. Schultheis, A. Silvestri, L. C. Smith, C. Tao, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, F. Vernizzi, G. Verza, N. A. Walton

High Energy Astrophysical Phenomena · Cross-listed from nucl-th

Thermal and Magnetic effects on Bulk Viscosity in Binary Neutron Star Mergers

Pranjal Tambe, Debarati Chatterjee, Mark Alford et al. (+1 more)

Astrophysical scenarios such as binary neutron star mergers, protoneutron stars, and core-collapse supernovae involve finite temperatures and strong magnetic fields. Previous studies on the effect of magnetic fields on flavor-equilibration processes relied on the Fermi surface approximation, which is not a reliable approximation in the neutrino-transparent regime of matter in supernovae or neutron star mergers. In a recent study, we went beyond the Fermi surface approximation, performing the full phase space integral to obtain direct Urca rates in a background magnetic field. In this work, we extend these calculations to incorporate the collisional broadening (modified Urca) contribution. We use the recently developed nucleon width approximation, which naturally includes the magnetic field dependence of all contributions. We demonstrate the impact of magnetic fields on the flavor-equilibrium condition for two finite-temperature equations of state with different direct Urca thresholds. We also study the impact of magnetic fields on the bulk viscous dissipation of density oscillations relevant in postmerger scenarios.
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All authors Pranjal Tambe, Debarati Chatterjee, Mark Alford, Alexander Haber

High Energy Astrophysical Phenomena

Search for synchrotron pair echo emission following KM3-230213A

Angelina Sherman, Nestor Mirabal, David Guevel et al. (+3 more)

The KM3NeT Collaboration has recently reported the detection of an extraordinary ultra-high-energy neutrino event with an energy of 220 PeV. Ultrahigh energy neutrinos and gamma-rays are co-produced in ultrahigh energy cosmic-ray interactions. If a UHE neutrino was produced within the large-scale structure around the source where it was accelerated, gamma-ray emission may be expected via the synchrotron pair echo mechanism. Here, we develop the synchrotron pair echo model in the specific context of the KM3NeT neutrino. Motivated by the fact that the synchrotron pair echo signal is expected to peak in the GeV - TeV band, and that the signal may appear as a dim, transient source, we investigate the data collected by the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope for transient and sub-threshold gamma-ray sources in the vicinity of the KM3NeT neutrino. We find three sub-threshold sources with TS $\gtrsim 16$ within $3.5^{\circ}$ of the neutrino event not included in any existing Fermi-LAT catalogs, but note that none of the identified sub-threshold sources seem to be compelling candidates for synchrotron pair echo emission.
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All authors Angelina Sherman, Nestor Mirabal, David Guevel, Ke Fang, Kohta Murase, Elizabeth Hays

Astrophysics of Galaxies

The Low-Frequency Spectra of Radio Pulsars

Ting Yu, Zhongli Zhang, Hongyu Gong et al. (+1 more)

Low-frequency spectral studies of radio pulsars represent a key method for uncovering their emission mechanisms, magnetospheric structure, and signal interactions with the surrounding interstellar medium (ISM). In recent years, more next-generation low-frequency radio telescopes (e.g., LOFAR, LWA and MWA) have enriched the observational window below 350 MHz, enabling more detailed explorations of the ISM effects, such as absorption and scattering, resulting in diverse spectral behaviors observed across different pulsars. This paper reviews the morphology of pulsar radio spectra, advances in spectral modeling, and the key physical processes governing the low-frequency emission. Looking ahead, next-generation instruments such as SKA-Low - with their unprecedented sensitivity - are expected to resolve outstanding questions in pulsar emission processes, offering insights into the extreme physical regimes governing these exotic objects.
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All authors Ting Yu, Zhongli Zhang, Hongyu Gong, Zhigang Wen

Cosmology and Nongalactic Astrophysics

Investigating the $w$CDM Model with Latest DESI BAO Observations

Manisg Yadav, Archana Dixit, M. S. Barak et al. (+1 more)

In this study, we explore the impact of various combinations of CMB-independent datasets, including the recent DESI BAO measurements, on the equation of state (EoS) of dark energy and other cosmological parameters within the framework of the dynamical dark energy model ($w$CDM). Assuming a constant EoS parameter for dark energy, we derive constraints on the free parameters of the model using observational datasets such as DESI BAO, BBN, Observational Hubble Data (OHD), and Pantheon Plus (SN$^+$) $\&$ SH0ES. Our analysis examines the deviations of the $w$CDM model from the standard $\Lambda$CDM scenario and assesses its implications for cosmological tensions, particularly the $H_0$ tension [$\text{km} \text{s}^{-1} \text{Mpc}^{-1}$]. We find that the combination of DESI BAO + BBN + OHD + SN$^+$ (DESI BAO + BBN + OHD + SN$^+$ &SH0ES) datasets provides constraints on $w_{\mathrm{de}0}$, suggesting a possible deviation from the cosmological constant scenario at a significance level of $1.6\sigma$ ($1.4\sigma$), respectively. Furthermore, we observe an inverse correlation between $w_{\text{de0}}$ and $H_0$, which highlights the role of dark energy dynamics in resolving the tension $H_0$ by approximately $2.1\sigma(0.8\sigma)$ from DESI BAO + BBN + OHD (DESI BAO + BBN + OHD + SN$^+$ &SH0ES) datasets, respectively. Our findings offer valuable insights into the nature of dark energy and its influence on the cosmic expansion history, with implications for future observational efforts. We utilize the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) to evaluate our model's performance. The results indicate that the $w$CDM model demonstrates superior effectiveness.
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All authors Manisg Yadav, Archana Dixit, M. S. Barak, Anirudh Pradhan

High Energy Astrophysical Phenomena

3D Moving-mesh Hydrodynamical Simulations of Wind/Jet Driven Ultraluminous X-ray Source Bubbles

Jiahui Huang, Ken Ohsuga, Hua Feng et al. (+1 more)

We perform 3 dimensional moving-mesh hydrodynamical simulations of bubble nebulae around ultraluminous X-ray sources, using state-of-the-art software AREPO. We use a Monte-Carlo method to inject outflows with uniform mass outflow rate and momentum, in a conical funnel with a specific half opening angle. Simulation results show that the morphology of the bubble is determined by the initial momentum of the outflows, while the mechanical power of the outflows only influences the size of the bubble without changing its shape. Low mechanical power also results in a short cooling timescale of the system, leading to an early collapse of the bubble shell. The half opening angle of the outflows and the viewing angle of the system determine the observed bubble eccentricity together. Compared with the observational morphology of the ULX bubble sources NGC 55 ULX-1 and NGC 1313 X-2, our simulation favors the fact that the high velocity outflows of the accretion disks in these two systems are confined in a narrow funnel region.
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All authors Jiahui Huang, Ken Ohsuga, Hua Feng, Hui Li

Astrophysics of Galaxies

HST Confirms Sub-5 kpc Dual Quasar Pairs at Cosmic Noon

Qian Wang, Xuheng Ding, John Silverman et al. (+12 more)

During cosmic noon ($z\sim1-3$), when both star formation and black hole growth peaked, galaxy mergers are predicted to trigger dual active galactic nuclei (AGN) that eventually coalesce as supermassive black hole (SMBH) binaries. However, observations of dual quasars with sub-5 kpc separations-the critical phase preceding final coalescence-have remained challenging due to angular resolution limitations. We present the discovery and confirmation of two sub-arcsecond dual quasars at $z>1$, selected from 59,025 SDSS quasars, which fall within the footprint of the Hyper Suprime-Cam Survey. Using high-resolution Hubble Space Telescope (HST) imaging and slitless spectroscopy, we confirmed SDSS J1625+4309 ($z=1.647$, separation 0.55"/4.7 kpc) and SDSS J0229$-$0514 ($z=3.174$, separation 0.42"/3.2 kpc), probing the sub-5 kpc separation regime. Through novel combination of WFC3/IR direct imaging (F140W) and grism spectroscopy (G141), we resolve both components morphologically and spectroscopically confirm their dual nature via detection of H$\beta$+[OIII] and MgII emission lines in each nucleus. Two-dimensional image decomposition reveals distinct host galaxy morphologies: J1625+4309 shows an extended, disturbed structure ($R_e$=4.7 kpc) indicative of an ongoing major merger, while J0229$-$0514 exhibits a compact host ($R_e$=1.4 kpc) suggesting an advanced coalescence stage. Black hole mass estimates based on virial relations yield M$_{\mathrm{BH}} \sim 10^{8.1}-10^{8.7} M_\odot$ with line-of-sight velocity offsets of $(0.7\pm0.1)\times10^{3}$ km s$^{-1}$ and $(1.0\pm0.2)\times10^{3}$ km s$^{-1}$, respectively. These confirmations directly constrain the frequency and properties of close dual quasars, opening new avenues for studying SMBH mergers at cosmic noon.
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All authors Qian Wang, Xuheng Ding, John Silverman, J. Xavier Prochaska, Tommaso Treu, Hassen M. Yesuf, Andrew D. Goulding, Masatoshi Imanishi, Nobunari Kashikawa, Issha Kayo, Kotaro Kohno, Kai Liao, Yoshiki Matsuoka, Michael A. Strauss, Shenli Tang

High Energy Astrophysical Phenomena

A study of 80 known pulsars at 185 MHz using MWA incoherent drift-scan observations

Ting Yu, Hongyu Gong, Zhifu Gao et al. (+4 more)

A systematic study of 80 known pulsars observed at 185 MHz has been conducted using archival incoherent-sum data from the Murchison Widefield Array (MWA). The dataset comprises 48 drift-scan observations from the MWA Voltage Capture System, covering approximately 30,000 square degrees of sky with sensitivities reaching about 8 mJy in the deepest regions. An optimized PRESTO-based search pipeline was deployed on the China SKA Regional Centre infrastructure. This enabled the detection of 80 known pulsars, representing a 60 percent increase over the previous census. Notably, this includes 30 pulsars with first-time detections at this frequency, of which pulse profiles and flux densities are presented. Spectral, scattering, and pulse-width properties were examined for the sample, providing observational constraints on low-frequency turnover, propagation effects, and width-period relations. This study highlights the value of wide-field, low-frequency time-domain surveys for constraining pulsar emission and propagation, offering empirical insights that may inform future observations with instruments such as SKA-Low.
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All authors Ting Yu, Hongyu Gong, Zhifu Gao, Zhongli Zhang, Zhigang Wen, Yujie Wang, Tao An

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

When inverse seesaw meets inverse electroweak phase transition: a novel path to leptogenesis

Wen-Yuan Ai, Peisi Huang and Ke-Pan Xie

We propose a new nonthermal leptogenesis mechanism triggered by the cosmic first-order phase transition. The Standard Model is extended with two generations of TeV-scale vectorlike leptons. The lighter generation gives rise to an inverse electroweak phase transition of the Higgs field at $T\sim200~{\rm GeV}$, restoring the symmetry, and resulting in relativistic bubble expansion in the space. The heavier generation is responsible for neutrino masses via the inverse seesaw mechanism. The interaction between bubble walls and particles in the plasma abundantly produces the vectorlike leptons, and they subsequently undergo CP-violating decay to generate the baryon asymmetry. This mechanism is testable at current and future particle experiments.
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Astrophysics of Galaxies

Galaxy Metallicity Gradients in the Reionization Epoch from the FIRE-2 Simulations

Xunda Sun, Xin Wang, Fangzhou Jiang et al. (+10 more)

We employ the high-redshift suite of FIRE-2 cosmological hydrodynamic zoom-in simulations to investigate the evolution of gas-phase metallicity radial gradients in galaxies in the epoch of reionization (EoR). Our sample consists of 22 galaxies spanning the redshift range $z \sim 10-5$. We find that galaxies at $z\sim10$ exhibit a median metallicity gradient of $-0.15\,\mathrm{dex\cdot kpc^{-1}}$ with substantial scatter, which gradually flatten to $-0.1\,\mathrm{dex\cdot kpc^{-1}}$ at $z\sim6$, accompanied by a reduction in scatter. In the EoR, metallicity gradients correlate positively with stellar mass: more massive galaxies display flatter gradients with smaller scatter, broadly consistent with recent JWST observations. At fixed stellar mass, galaxies with higher star formation rates (SFRs) exhibit steeper negative gradients, while sSFR shows a strong anti-correlation with gradient slope. Because EoR galaxies in FIRE-2 generally lack significant rotational support, we adopt the ratio of peak-to-peak velocity shear to twice the velocity dispersion ($\Delta v/2\sigma$) as a proxy for the strength of gas flows. We find a strong positive correlation between metallicity gradients and $\Delta v/2\sigma$: galaxies with lower $\Delta v/2\sigma$ (i.e., weaker gas flows) tend to exhibit steeper negative gradients. Furthermore, galaxies with steeper gradients display higher central SFR surface densities, suggesting localized star formation with inefficient interstellar medium mixing that drives inside-out chemical enrichment in galaxy evolution in the early Universe.
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All authors Xunda Sun, Xin Wang, Fangzhou Jiang, Houjun Mo, Luis C. Ho, Qianqiao Zhou, Xiangcheng Ma, Hu Zhan, Andrew Wetzel, Russell L. Graf, Philip F. Hopkins, Dusan Keres, Jonathan Stern

Solar and Stellar Astrophysics

The Influence of Magnetic Complexity of Active Regions on Solar Wind Properties During Solar Cycles 23 and 24

Xinzheng Shi, Hui Fu, Zhenghua Huang et al. (+3 more)

Linking solar wind properties to the activities and characteristics of its source regions can enhance our understanding of its origin and generation mechanisms. Using the Mount Wilson magnetic classification (MWMC), we categorize all active regions (ARs) between 1999 and 2020 into three groups: alpha, beta, and complex ARs. Subsequently, we classify the near-Earth AR solar wind into the corresponding three types based on the magnetic type of ARs. Our results show that alpha, beta, and complex ARs account for 19.99%, 66.67%, and 13.34% of all ARs, respectively, while their corresponding AR solar wind proportions are 16.96%, 45.18%, and 37.86%. The properties of solar wind from different types of ARs vary significantly. As the magnetic complexity of ARs increases, the corresponding AR solar wind exhibits higher magnetic field strength, charge states, helium abundance (A_He), and first ionization potential (FIP) bias. Our results demonstrate that complex ARs are more effective at generating solar wind. Additionally, the strong magnetic fields and frequent magnetic activities in complex ARs can heat the plasma to higher temperatures and effectively transport helium-rich materials from the lower atmosphere to the upper corona.
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All authors Xinzheng Shi, Hui Fu, Zhenghua Huang, Limei Yan, Qi Liu, Lidong Xia

Astrophysics of Galaxies

LAMOST Medium-resolution Spectroscopic Survey of the Rosette Nebula

Li-Yue Zhang, Chao-Jian Wu, Xuan Fang et al. (+4 more)

We report multi-fiber, medium-resolution spectroscopy of the Rosette Nebula with full spatial coverages, and present a table of the nebular parameters based on the spatially-resolved measurements of emission lines. These new observations were conducted through the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Comprehensive analyses were performed on a total of 3854 high-quality nebular spectra, so far the most extensive spectral dataset available for this nebula that encompasses an area of 4.52 square degrees. Various physical parameters, including relative line intensities, radial velocities (RVs), and full widths at half maximum (FWHMs), were derived through measurements of the H-alpha, [N II] 6548,6584 and [S II] 6716,6731 emission lines detected in the LAMOST MRS-N spectra. For the first time, we found a bow-shaped feature in the spatial distribution of RVs of the Rosette Nebula. Moreover, the spatial distributions of RVs and FWHMs, as well as additional parameters such as gas temperature and turbulent velocity in the vicinity of the nebula, indicate possible interaction between Rosette and the nearby supernova remnant (SNR), Monoceros Loop. Our new observations provide indispensable measurements of the Rosette Nebula. The parameter table in particular can be used as valuable constraint on the chemo-dynamical modeling of the nebula, which will enable deeper understanding of the characteristics of this H II region.
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All authors Li-Yue Zhang, Chao-Jian Wu, Xuan Fang, Wei Zhang, Juan-Juan Ren, Jian-Jun Chen, Hong Wu

High Energy Astrophysical Phenomena

A Sharper View of the X-ray Spectrum of MCG–6-30-15 with XRISM, XMM-Newton and NuSTAR

Laura W. Brenneman, Daniel R. Wilkins, Anna Ogorzałek et al. (+15 more)

We present a time-averaged spectral analysis of the 2024 XRISM observation of the narrow-line Seyfert-1 galaxy MCG–6-30-15, taken contemporaneously with XMM-Newton and NuSTAR. Our analysis leverages a unique combination of broadband and high-resolution X-ray spectroscopy to definitively isolate and characterize both broad and narrow emission and absorption features in this source. The best-fitting model for the joint spectral analysis is very well described by reflection from the inner accretion disk illuminated by a compact corona, modified by multi-zone ionized absorption from an outflowing wind along the line of sight. The XRISM/Resolve data confirm that a strong, relativistically-broadened Fe K$\alpha$ emission line is required in order to obtain an adequate model fit. The Resolve data additionally verify the presence of a $v_{\rm out} \sim 2300$ km/s component of this outflowing wind, find tentative evidence for a $v_{\rm out} \sim 20,000$ km/s wind component, and indicate that the reflection from distant, neutral material may originate in a non-uniform structure rather than the traditional torus of AGN unification schemes. Though a rapid prograde black hole spin is statistically preferred by the best-fitting model, consistent with previous results, the AGN flux variability over the course of the observation complicates the interpretation of the time-averaged spectra. This insight, clarified by the combination of high signal-to-noise and high spectral resolution in the joint dataset, emphasizes the importance of time-resolved, high-resolution spectral analysis in unambiguously measuring the physical properties of variable AGN.
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All authors Laura W. Brenneman, Daniel R. Wilkins, Anna Ogorzałek, Daniele Rogantini, Andrew C. Fabian, Javier A. García, Anna Juráňová, Misaki Mizumoto, Hirofumi Noda, Ehud Behar, Rozenn Boissay-Malaquin, Matteo Guainazzi, Takashi Okajima, Erika Hoffman, Noa Keshet, Jelle Kaastra, Erin Kara, Makoto Yamauchi

Astrophysics of Galaxies

Tides from the cloud can induce the fast disruption of star clusters and offer an explanation for Gaia strings

Xiao-Tong Chen and Guang-Xing Li

Young stars form in clusters within molecular clouds, but older stars are evenly distributed across the galactic disk, necessitating an explanation for cluster dissolution. We analytically study tidal forces from cold molecular clouds as a key mechanism for accelerated cluster disruption. Cloud tides, caused by the gravitational pull of the parent cloud along the radial direction, arise from the spatial gradient of gravitational acceleration and drive cluster disruption. This mechanism activates after gas expulsion and remains effective until the cloud is disrupted by stellar feedback or the cluster moves away. Cloud tides act on gas-deprived clusters, causing exponential expansion on a tidal timescale of $t_{\rm tidal,ext} = \sqrt{3/(8\pi G\rho_{\rm mean})}$, where $\rho_{\rm mean}$ is the cloud's density at the cluster's location. With a duration of a few Myr, cloud tides can lead to a 10 times increase of the cluster size, producing bar-like elongated stellar aggregations resembling Gaia strings. These results establish cloud tides as a potentially important mechanism for star cluster disruption.
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Cosmology and Nongalactic Astrophysics

Constraints on the interacting holographic dark energy models: implications from background and perturbations data

N.Nazari Pooya

In this study, we employ a two-step method to analyze models of holographic dark energy (HDE) and interacting holographic dark energy (IHDE), incorporating three distinct dark energy (DE)-dark matter (DM) interaction terms. First, using the latest background dataset, we conduct a Markov chain Monte Carlo (MCMC) analysis to constrain the free parameters of the models. Then, we assess the models against each other using the key background parameters and compare them to the $\Lambda$CDM standard model. Our results show that at high redshifts, the equation of state (EoS) parameter related to the models for both homogeneous and clustered DE cases falls within the quintessence region. However, as we approach the present time, all models except HDE transition into the phantom region, and two models cross the phantom line earlier than others. In the next step, we focus on the evolution of perturbations in DE and DM. Using background and growth rate data, we constrain parameters including $\sigma_8$. We then investigate the evolution of the growth rate of matter perturbations, $f\sigma_8(z)$, and its deviation, $\Delta f \sigma_8$, from the $\Lambda$CDM model. The HDE model shows the best agreement with observational data, while other models predict varying growth rates compared to $\Lambda$CDM. Finally, we demonstrate through Akaike and Bayesian information criteria (AIC and BIC) analysis that the compatibility of models with observational data depends on the type of data used, the DE-DM interaction term, and the assumptions regarding DE homogeneity and clustering. Our results suggest that homogeneous DE models yield more agreement with observational data than clustered DE models.
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Thursday 9 October

Instrumentation and Methods for Astrophysics

Generating background-corrected VPHAS+ HiPS with Montage

Thomas Boch, Caroline Bot and Pierre Fernique

We present a technique for creating background-corrected HiPS (Hierarchical Progressive Surveys) from VPHAS+ images using the Montage toolkit. By combining advanced background correction methods and HiPS generation workflows, we produced high-quality color HiPS from the VST Photometric H-alpha Survey of the Southern Galactic Plane and Bulge (VPHAS+). These HiPS have been made publicly available through the HiPS network and serve as an invaluable addition to the HiPS ecosystem for astronomers worldwide.
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