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Physics Astrophysics

astro-ph Watch Astrophysics

Friday 13 February

Astrophysics of Galaxies

Characterizing Lyman alpha emission from high-redshift galaxies

Samuel Gagnon-Hartman, Andrei Mesinger, Ivan Nikolić et al. (+2 more)

The Lyman $\alpha$ (Ly$\alpha$) line from high-redshift galaxies is a powerful probe of the Epoch of Reionization (EoR). Neutral hydrogen in the intergalactic medium (IGM) can significantly attenuate the emergent Ly$\alpha$ line, even in the damping wing of the cross-section. However, interpreting this damping wing imprint relies on our prior knowledge of the spectrum that escapes from the galaxy and its environs into the IGM. This emergent spectrum is highly sensitive to the composition and geometry of the interstellar and circumgalactic media, and so exhibits a large galaxy to galaxy scatter. Characterizing this scatter is further complicated by non-trivial selection effects introduced by observational surveys. Here we build a flexible, empirical model for the emergent Ly$\alpha$ spectra. Our model characterizes the emergent Ly$\alpha$ luminosity, the velocity offset of the Ly$\alpha$ line with respect to the systemic redshift, and the H$\alpha$ luminosity, with multivariate probability distributions conditioned on the UV magnitude. We constrain these distributions using $z\sim5-6$ galaxy observations with VLT MUSE and JWST NIRCam, forward-modeling observational selection functions together with galaxy parameters. Our model results in Ly$\alpha$ equivalent width distributions that are a better match to (independent) Subaru observations than previous empirical models. The extended distributions of Ly$\alpha$ equivalent widths and velocity offsets we obtain could facilitate Ly$\alpha$ transmission during the early stages of the EoR. We also illustrate how our model can be used to identify GN-z11-like outliers, potentially originating from merging systems. We publish fitting functions and make our model publicly available.
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All authors Samuel Gagnon-Hartman, Andrei Mesinger, Ivan Nikolić, Eleonora Parlanti, Giacomo Venturi

Instrumentation and Methods for Astrophysics

Dyad: a binary-star dynamics and statistics library for Python

Amery Gration

Dyad is a Python library for studying the dynamics of binary stars considered as gravitational two-body systems. The dynamics of a binary star are determined by its primary and secondary stars' masses along with the secondary star's six orbital elements as defined in a frame comoving with the primary star. In a population of binary stars these eight parameters vary from member to member and can each be treated as a random variable having some probability distribution. Dyad provides a class, dyad.TwoBody, and a module, dyad.stats, for dealing with such a population of binary stars. The dyad.TwoBody class represents a gravitational two-body system while the dyad.stats module provides a suite of classes representing the probability distributions of (1) stellar masses (including those proposed by Kroupa, 2001, and Salpeter, 1955) as well as (2) mass ratios and orbital elements (including those proposed by Duquennoy & Mayor, 1991, and Moe & Di Stefano, 2017). The software repository is at https://github.com/AmeryGration/dyad .
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th

Physical Predictions in Closed Quantum Gravity

Yasunori Nomura and Tomonori Ugajin

Recent developments in gravitational path integrals indicate that the nonperturbative physical Hilbert space of a closed universe is one-dimensional within each superselection sector. This raises a basic puzzle: how can a unique quantum-gravity state give rise to semiclassical physics, measurement outcomes, and classical probabilities? In this paper, we develop a framework in which nontrivial and statistically stable predictions emerge despite the one-dimensionality of the fully constrained Hilbert space. The key idea is to extract physical predictions in an enlarged, unconstrained Hilbert space by conditioning on observational data. We show that partial observability – reflecting the limited access of observers to the degrees of freedom of the universe – suppresses ensemble fluctuations associated with microscopic structure in the gravitational path integral, thereby restoring semiclassical predictability with exponential accuracy. We formulate the construction explicitly including contributions from the Hartle–Hawking no-boundary state, define a gauge-invariant Hilbert space for observations via a density operator, and generalize the formalism to conditioning on histories, clarifying the emergence of classical probabilities and an effective arrow of time. Finally, we explore whether this framework can support a realistic cosmology and identify assumptions that the underlying theory of quantum gravity must satisfy.
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Astrophysics of Galaxies

Modeling Globular Cluster Stellar Streams with a Basis-Expansion N-body Code

Brian T. Cook, Kerwann Tep, Carl L. Rodriguez et al. (+6 more)

Globular cluster stellar streams probe galaxy-formation processes and can potentially reveal the distribution of dark matter in galaxies. In many theoretical studies, streams are modeled with particle-spray or direct N-body codes. But particle-spray methods abstract away the internal dynamics of the progenitor by making strong assumptions about the escape physics, while direct N-body is prohibitively expensive for realistic (N>10^5) systems. In this paper, we present the stream-modeling capabilities of KRIOS, a new basis-expansion N-body code for collisional stellar dynamics, that bridges this runtime vs. accuracy gap. We show that KRIOS reproduces NBODY6++GPU cluster models, and their associated streams, more accurately than particle spray in a fraction of the NBODY6++GPU wall-clock time. We then compare KRIOS to various particle-spray methods on 10 orbits similar to known Milky Way streams. The morphology and kinematics of these streams most disagree when the progenitor is tightly bound to the host, as these systems are often subject to stronger tidal forces. Finally, we discuss which elements of the progenitor physics are most important for modeling stellar streams and how these might be incorporated into particle-spray methods.
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All authors Brian T. Cook, Kerwann Tep, Carl L. Rodriguez, Leah English, Tjitske Starkenburg, Robyn Sanderson, Newlin C. Weatherford, Sarah Pearson, Nondh Panithanpaisal

Cosmology and Nongalactic Astrophysics

CMB Spectral Distortions from Resonant Conversions in Atomic Dark Sectors

Duncan K. Adams, Jared Barron, Bryce Cyr et al. (+1 more)

Dark sectors consisting of atomic constituents (electrons, protons, and photons) offer a well-motivated extension to the Standard Model while providing multiple avenues for phenomenological study. In this work, we explore the impact of conversions between the dark and Standard Model photons in the primordial CMB spectral distortion epoch ($10^3 \lesssim z \lesssim 10^6$). These conversions are resonantly enhanced when the induced thermal masses of both photonic species are equal, thus leading to the possibility that sizeable distortions can be produced. To this end, we solve the Boltzmann equation at early times to determine the (irreducible) freeze-in or freeze-out abundance of dark photons. This procedure also allows us to update the limits on generic milli-charged dark sectors using the ACT DR6 bound on the number of effective radiative degrees of freedom ($N_{\rm eff}$). By then modeling the evolution of the thermal masses in both sectors, we compute the primordial CMB distortion using the Landau-Zener formalism. We find that when the dark electron and proton are roughly similar in mass (the positronium limit), current spectral distortion data from the COBE/FIRAS instrument is able to rule out novel regions of parameter space. We also forecast bounds from the proposed FOSSIL satellite, finding that spectral distortions can also be used to probe the ultra-low dark electric charge regions of parameter space, which are difficult to investigate by other means.
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All authors Duncan K. Adams, Jared Barron, Bryce Cyr, Xiuyuan Zhang

Astrophysics of Galaxies

Ultramassive Black Holes and the Three $M$-$\sigma$ Relations

Andrew King

I consider recent observations of ultramassive black holes. These appear to confirm theoretical predictions that the relation between central black hole mass $M$ and spheroid velocity dispersion $\sigma$ has the same form $M \propto \sigma^4$ in spiral galaxies, elliptical galaxies, and cluster ellipticals, but has differing normalizations. These arise from the need for longer black hole accretion episodes to expel the gas otherwise potentially able to feed the holes in the latter two types of host. In a sample drawn from a mixture of galaxy host types the fitted power of $\sigma$ will slightly exceed the theoretically-derived value of 4 because of the differing normalizations. The observed hole masses do not currently reach the theoretical maximum values possible for disc accretion, set by the equality of the ISCO and self-gravity radii, probably because the host galaxies have insufficient gas.
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High Energy Astrophysical Phenomena

$\texttt{GPUmonty}$: A GPU-accelerated relativistic Monte Carlo radiative transfer code

Pedro Naethe Motta, Rodrigo Nemmen and Abhishek V. Joshi

We introduce $\texttt{GPUmonty}$, a CUDA/C-based Monte Carlo radiative transfer code accelerated using graphics processing units (GPUs). $\texttt{GPUmonty}$ derives from the CPU-based code $\texttt{grmonty}$ and offloads the most computationally expensive stages of the calculation – superphoton generation, sampling, tracking, and scattering – to the GPU. Whereas $\texttt{grmonty}$ handles photons sequentially, $\texttt{GPUmonty}$ processes large numbers of superphotons concurrently, leveraging the single-instruction, multiple-thread (SIMT) execution model of modern GPUs. Benchmarks demonstrate a speedup of about $12\times$ relative to the original CPU implementation on a single GPU, with runtime limited primarily by register pressure rather than compute or memory bandwidth saturation. We validate the implementation through analytic tests for a optically thin synchrotron sphere, as well as comparisons with $\texttt{igrmonty}$ for scattering synchrotron sphere and GRMHD simulation data. Relative errors remain below a percent level and convergence is consistent with the expected $N_{\rm s}^{-1/2}$ Monte Carlo scaling. By significantly reducing computational costs, GPUmonty enables the extensive parameter space surveys and faster spectra modeling required to interpret horizon-scale observations of supermassive black holes. $\texttt{GPUmonty}$ is publicly available under the GNU General Public License.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Addressing the Hubble tension with Sterile Neutrino Dark Matter

Debtosh Chowdhury and Md Sariful Islam

One of the promising dark matter (DM) candidates is a keV-scale sterile neutrino. In the early universe, the observed relic of the sterile neutrino DM is generated via the Dodelson-Widrow mechanism. However, this production scenario is severely constrained by various astrophysical observations. Many non-standard interactions between active ($\nu_a$) and sterile ($\nu_s$) neutrinos have been proposed to evade these astrophysical bounds. Here, we study sterile neutrinos in the context of a mass-varying scenario by coupling both active and sterile neutrinos to a scalar field. This novel mechanism opens up a new parameter space that generates the observed DM relic and addresses the Hubble tension. We find that the resulting parameter space can be fully probed by future X-ray missions.
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Solar and Stellar Astrophysics

V515 And: An Intermediate Polar in the Period Gap Exhibiting Outbursts

Srinivas M Rao, Jeewan C Pandey, Nikita Rawat et al. (+4 more)

Using long-term observations from the Transiting Exoplanet Survey Satellite (TESS) along with spectroscopic observations from the 3.6 m Devasthal Optical Telescope (DOT), we present a comprehensive time-series and spectral analysis of the intermediate polar V515 And. Our analysis reveals that V515 And resides within the period gap, with the detection of its orbital period of 2.73116 h. Additionally, we confirm the earlier findings of the spin and beat periods to be 465.4721 s and 488.6067 s, respectively. The time-resolved timing analysis reveals that V515 And undergoes changes in its accretion geometry, not only between different TESS sectors but also within individual sector observations. The system exhibits a transition in the dominant accretion mode, switching between disc-fed and stream-fed accretion. In the TESS light curve, we identify two successive outburst-like episodes, each persisting for roughly a day and reaching peak luminosities of $2.7\times10^{33}$ and $1.9\times10^{33}$ erg s$^{-1}$. Our analysis suggests that these bursts belong to the recently proposed class of micronovae. The optical spectrum of V515 And is characterised by strong Balmer and He II emission lines and shows an inverse Balmer decrement indicating the magnetic nature of the source.
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All authors Srinivas M Rao, Jeewan C Pandey, Nikita Rawat, Simone Scaringi, Arti Joshi, David A. H. Buckley, Ajay Kumar Singh

High Energy Astrophysical Phenomena

An updated constraint for the Gravitational Wave Background from the Gamma-ray Pulsar Timing Array

Serena Valtolina, Colin J. Clark, Rutger van Haasteren et al. (+5 more)

Fermi LAT observations of gamma-ray pulsars can be used to build a pulsar timing array (PTA) experiment to search for gravitational wave (GW) signals at nanohertz frequencies. At those frequencies, the dominant signal is expected to be a stochastic gravitational wave background (GWB) produced by the incoherent superposition of the quasi-monochromatic GW emissions from a population of supermassive black hole binaries. While the radio PTAs have recently announced compelling evidence for a GWB signal with a power law spectrum of strain amplitude $\approx2-3\times10^{-15}$ (at the frequency of $1 {\rm yr}^{-1}$), in 2022 an analysis of $12.5$ years of Fermi data for 35 pulsars led to an upper limit of $1\times10^{-14}$ for the GWB amplitude. The analysis was carried out on times-of-arrival (TOAs) obtained by folding from six months up to one year of photon observations. A photon-by-photon approach was also tested to infer constraints on the GWB amplitude from individual pulsars, but without accounting for the cross-pulsar correlations that a GWB would induce. Here, we reanalyse the same dataset using a regularized likelihood method that correctly models cross-pulsar correlations directly from the photons, while additionally marginalising over the uncertain pulse profile shape. While the two methods are not expected to have significant differences in sensitivity, we prove through simulations of gamma-ray PTA datasets that the photon-by-photon method for GWB recoveries is, statistically, more robust. The resulting upper limit obtained for the GWB strain amplitude is $1.2\times10^{-14}$, indicating that the improved method yields a consistent result with the previous analyses.
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All authors Serena Valtolina, Colin J. Clark, Rutger van Haasteren, Aurélien Chalumeau, H. Thankful Cromartie, Matthew Kerr, Lars Nieder, Aditya Parthasarathy

Solar and Stellar Astrophysics

Presaging Doppler beaming discoveries of double white dwarfs during the Rubin LSST era

Gautham Adamane Pallathadka, Yossef Zenati, Nadia L. Zakamska et al. (+2 more)

Double white dwarfs (DWDs) are by far the most common compact binaries in the Milky Way, are important low-frequency gravitational-wave sources, and in some cases merge to become Type Ia supernovae. So far, no DWD has been identified solely through relativistic Doppler beaming, even though the beaming amplitude directly relates to the radial velocity semi-amplitude. In this work, we initiate a comprehensive binary population synthesis using SeBa and incorporate the resulting binaries into a tripartite Galaxy model. Our proof-of-concept simulations demonstrate that the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) can reliably recover relatively bright ($r \lesssim20~$mag) unequal-mass binaries in compact orbits with P $\approx$ 10-600 minutes with moderate to high inclinations. We find that LSST can detect at least 287 short-period DWDs, of which 47 are LISA-detectable gravitational wave sources. LSST lightcurves allow us to readily determine the period and fully characterize the orbit, in contrast with the challenges of orbit determination for DWDs in spectroscopic searches. The formation of unequal mass, short-period DWDs strongly depends on the assumptions regarding the mass-transfer phases during binary population synthesis, and the total number and characteristics of Doppler-beamed DWD systems observed in LSST will provide new tests of models of stellar binary evolution. Here, we lay the foundation for the comprehensive integration of synthetic Galactic binary population into realistic LSST survey simulations, thereby enabling quantitative forecasts of the number and characteristics of any binary sub-population during the LSST era.
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All authors Gautham Adamane Pallathadka, Yossef Zenati, Nadia L. Zakamska, Ngan H. Nguyen, Anthony L. Piro

Earth and Planetary Astrophysics

TIC65910228b: A single-transit discovery of a massive long-period warm Jupiter with TESS

Felipe I. Rojas, Rafael Brahm, Matías I. Jones et al. (+27 more)

Context. Warm Jupiters are excellent case studies for the investigation of giant planet internal structures and formation theories. However, the sample of long-period transiting giants is still small today for a better understanding of this population. Aims. Starting from a single transit found in the Transiting Exoplanet Survey Satellite (TESS) data, we confirm the planetary nature of the signal and measure its orbital parameters, mass, and radius. We put this system in the context of long-period giant transiting planets and analyzed the viability to sustain atmospheric or dynamical follow-up. Methods. We carried out a spectroscopic follow-up using FEROS and PLATOSpec to obtain precise radial velocities. We added a photometric follow-up with HATPI and Observatoire Moana to obtain a more precise estimate of the orbital period. We derived the orbital and physical parameters through a joint analysis of this data. Results. We report the discovery and characterization of TIC65910228b, a transiting warm Jupiter with a mass of $4.554 \pm 0.255$ $M_J$ and a radius of $1.088 \pm 0.061$ $R_J$, orbiting an evolved F-type star every $\sim 180.52$ days in an eccentric orbit ($e = 0.25 \pm 0.04$). Conclusions. This planet joins a still under-explored population of long-period ($P > 100$) massive ($M_p > 4$ $M_J$) transiting giant planets, being one of the few with a mild eccentricity. This target is a nice example of the potential of single-transit events to populate this region of the parameter space.
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All authors Felipe I. Rojas, Rafael Brahm, Matías I. Jones, Márcio Catelan, Jozef Liptak, Lorena Acuña, Jan Eberhardt, Néstor Espinoza, Thomas Henning, Andrés Jordán, Yared Reinarz, Marcelo Tala Pinto, Trifon Trifonov, Michaela Vítková, Luca Antonucci, Gaspar Bakos, Attila Bódi, Gavin Boyle, Zoltán Csubry, Joel Hartman, Jan Janík, Petr Kabáth, Anthony Keyes, Markus Roth, Petr Škoda, Alton Spencer, Vincent Suc, Geert Jan Talens, Jan Vaclavik, Leonardo Vanzi

Astrophysics of Galaxies

H$_2$ Ortho-Para Spin Conversion on Inhomogeneous Grain Surfaces. II. impact of the rotational energy difference between adsorbed ortho-H$_2$ and para-H$_2$ and implication to deuterium fractionation chemistry

Kenji Furuya, Toshiki Sugimoto, Kazunari Iwasaki et al. (+2 more)

We investigate how the H$_2$ ortho-to-para ratio (OPR) and dueterium fractionation in star-forming regions are affected by nuclear spin conversion (NSC) on dust grains. Particular focus is placed on the rotational energy difference between ortho-H$_2$ (o-H$_2$) and para-H$_2$ (p-H$_2$) on grain surfaces. While the ground state of o-H$_2$ has a higher rotational energy than that of p-H$_2$ by 170.5 K in the gas phase, this energy difference is expected to become smaller on solid surfaces, where interactions between the surface and adsorbed H$_2$ molecules affect their rotational motion. A previous study by Furuya et al. (2019) developed a rigorous formulation of the rate for the temporal variation of the H$_2$ OPR via the NSC on grains, assuming that adsorbed o-H$_2$ has higher rotational energy than adsorbed p-H$_2$ by 170.5 K, as in the gas phase. In this work, we relax the assumption and re-evaluate the rate, varying the rotational energy difference between their ground states. The re-evaluated rate is incorporated into a gas-ice astrochemical model to study the evolution of the H$_2$ OPR and the deuterium fractionation in prestellar cores and the outer, cold regions of protostellar envelopes. The inclusion of the NSC on grains reduces the timescale of the H2 OPR evolution and thus the deuterium fractionation, at densities of >10$^4$ cm$^{-3}$ and temperatures of <14-16 K (depending on the rotational energy difference), when the ionization rate of H$_2$ is 10$^{-17}$ s$^{-1}$.
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All authors Kenji Furuya, Toshiki Sugimoto, Kazunari Iwasaki, Masashi Tsuge, Naoki Watanabe

Astrophysics of Galaxies

Spatially resolved star-formation histories of local post-starburst galaxies: Starburst and quenching spatial patterns consistent with recent mergers

Ho-Hin Leung, Vivienne Wild, Michail Papathomas et al. (+6 more)

Post-starburst (PSB) galaxies, having recently experienced a starburst followed by rapid quenching, are excellent laboratories to probe physical mechanisms that drive starbursts and shutting down of star formation. Integral-field spectroscopy reveals the galaxies' spatially-resolved properties, where observed directional patterns can be linked to the galaxies' past evolution. We measure the resolved star-formation histories (SFHs), stellar metallicity evolution and dust properties of three local PSBs from the MaNGA survey, down to $0.5$" resolution ($\sim0.3\,$kpc) using a hierarchical Bayesian model. Local parameters were constrained simultaneously with parameters describing spatial trends. We found that all three galaxies first experienced an outer, weaker and slower quenching starburst, followed by a central, stronger and faster quenching starburst that peaked $\sim 1\,$Gyr after the first. The central starbursts induced a significantly stronger rise in stellar metallicity compared to the outer starbursts. These results are consistent with the effects of a recent gas-rich (wet) merger, where the first pericentre passage triggered starbursts in the outer regions, while the later coalescence triggers a stronger centralised starburst. We find non-axisymmetric features in the maps of burst mass fraction and dust attenuation in all galaxies, which could be caused by tidal effects during the recent merger. Comparisons with literature binary merger simulations suggests that the galaxies' rapid quenching was driven by gas consumption and the stabilisation against gas gravitational collapse by a growing spheroid, while AGN feedback was not necessarily a primary cause.
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All authors Ho-Hin Leung, Vivienne Wild, Michail Papathomas, Daniel J. Mortlock, Amy L. Rankine, Emma Curtis-Lake, Yirui Zheng, Adam C. Carnall, Peter H. Johansson

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Evolution of Linear Perturbations under Time-Dependent Hubble Friction I: SR-USR-SR Inflation

Wen Li and Chao Chen

The origin of the finite dip in the curvature power spectrum of instantaneous Slow-Roll (SR)-Ulta-Slow-Roll (USR)-SR inflation remains controversial at linear order, and its full spectral features still lack a complete asymptotic analytical description. We revisit linear perturbation dynamics in this framework. Using the junction method and asymptotic expansions of Hankel functions, we for the first time derive accurate and simple asymptotic expressions for mode evolution and the resulting power spectrum, based on three systematic rules for dominant-term identification across transitions. We find the finite dip arises from cancellation between two growing modes within linear perturbation theory, rather than between constant and growing terms as previously suggested. We also provide analytical descriptions of the amplitude enhancement and the two oscillatory patterns observed in the spectrum. All asypmtotic analytical results are validated by numerical calculations with the reconstructed SR-USR-SR inflationary potential.
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Earth and Planetary Astrophysics · Cross-listed from cond-mat.mtrl-sci

Negative thermal expansion in ice I polytypes

Leonardo del Rosso, A. Dominic Fortes, Daniele Colognesi et al. (+4 more)

The fundamental properties of ice have always attracted a lot of interest due to omnipresence of ice in many different natural contexts. Since cubic ice recently become experimentally accessible from a low-density gas hydrate precursor [1, 2], it has been possible to measure its density as a function of temperature in the whole thermodynamic range of metastability. We found strong analogies with respect to the other ice I polytype, i.e., hexagonal ice Ih [3], including the presence of a negative thermal expansion behavior at low temperature. Based on these results, a new enthalpy calculation quantifies the metastable nature of the cubic form and, consequently its inaccessibility from a "normal" ice Ih precursor.
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All authors Leonardo del Rosso, A. Dominic Fortes, Daniele Colognesi, Alberto Santonocito, Francesco Grazzi, Selene Berni, Milva Celli

Earth and Planetary Astrophysics

How hard is dust in debris disks?

Tobias Stein, Alexander V. Krivov and Torsten Löhne

Observational appearance of debris disks is largely controlled by collisional grinding of their dust grains. However, the mechanical strength of dust at sizes in the micrometer to millimeter range is poorly known. Recent studies suggested that dust particles in the Solar system might have a higher critical fragmentation energy $Q_{D}^*$ value than previously anticipated. Another recent study considered the Fomalhaut debris disk and found lower $Q_{D}^*$ values to provide better fits to the data. In order to constrain the mechanical strength of dust, we investigate collisional evolution of debris disks with $Q_{D}^*$ prescriptions differing by $\sim 3$ orders of magnitude. We find that, above a certain threshold $Q_{D}^*$ value, the disk's collisional evolution is dominated by rebounding – rather than disruptive or cratering – collisions. Rebounding (a.k.a. bouncing) collisions are those in which both impactors survive, being only slightly eroded and producing fragments that only carry a minor fraction of their mass. We show that disks dominated by rebounding collisions would have brightness profiles increasing outward outside the parent belt. Since such profiles are not observed, this places an upper limit on how hard the debris dust is allowed to be in order not to violate the observations. We derive an approximate analytic expression for this limit: $Q_{D}^* \approx (1/8) v_{K}^2(r)$ for grains close to the radiation pressure blowout size, where $v_{K}$ in the Keplerian circular speed at a distance $r$ from the star. This implies $Q_{D}^* \lesssim 10^{9...10} \,\hbox{erg}\,\hbox{g}^{-1}$ for micrometer-sized grains in typical debris disks. Even though rebounding collisions are not expected to affect debris disk evolution significantly, we emphasize that these collisions are actually much more frequent than disruptive and cratering ones in all debris disks.
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Instrumentation and Methods for Astrophysics

Photometric classification of supernovae detected by the Zwicky Transient Facility using noise augmentation

A. Townsend, J. Nordin, M. Kowalski et al. (+27 more)

Modern time-domain surveys, such as the Zwicky Transient Facility (ZTF), detect far more extragalactic transients than can be spectroscopically classified. Photometric classification offers a scalable alternative, enabling the identification of larger, fainter, and higher-redshift supernova samples suitable for applications such as Type Ia supernova (SN Ia) cosmology. We present a feature-based photometric classifier for SNe detected by ZTF, with the primary goal of constructing a photometric SN Ia sample for cosmological analyses. Our approach utilises the autoencoder architecture of ParSNIP (Boone 2021) to capture the intrinsic diversity of SN light curves. We trained the model on a spectroscopically classified ZTF SN sample, incorporating a realistic noise augmentation procedure that simulates the flux uncertainties of fainter sources. Light curve features were used to train a gradient-boosted decision tree classifier, implemented in both binary (SN Ia vs. non-Ia) and multi-class configurations. We validated our classifier on independent, fainter ZTF data with and without noise augmentation. To evaluate real-time performance, we also applied our classifier to live ZTF alerts and conducted a spectroscopic classification survey within the ePESSTO+ collaboration. We found that noise augmentation significantly improves classification performance, particularly for fainter sources. Our binary classifier achieves an SN Ia recall of (98.1 $\pm$ 0.4)%, averaged across five train-test splits. SN Ia recall exceeds 98% for events with a peak apparent magnitude up to 20 and more than 10 detections, and remains above 96% up to magnitude 20.5. Overall, 95% of sources were correctly classified in both binary and multi-class modes. Our classifier performs efficiently on real ZTF data and enables construction of a large photometric SN Ia sample for cosmology.
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All authors A. Townsend, J. Nordin, M. Kowalski, S. Reusch, J.P. Anderson, E.C. Bellm, U. Burgaz, T.X. Chen, T.-W. Chen, G. Dimitriadis, L. Galbany, A. Goobar, M.J. Graham, M. Gromadzki, C.P. Gutiérrez, D. Hale, C. Inserra, M. Kasliwal, Y.-L. Kim, K. Maguire, F.J. Masci, T.E. Müller-Bravo, D.A. Perley, R.L. Riddle, M. Rigault, J. van Santen, S. Schulze, M. Smith, J. Sollerman, S. Yang

Astrophysics of Galaxies

Self-Consistent Direct Method for Chemical Abundances in High-z Galaxies with JWST

Karla Z. Arellano-Córdova, J. Eduardo Méndez-Delgado, Sophia R. Flury et al. (+10 more)

The unprecedented rest-frame UV and optical coverage provided by JWST enables simultaneous constraints on the electron density (n$_{\rm e}$) and temperature (T$_{\rm e}$) of ionized gas in galaxies at z>5. We present a self-consistent direct method based on multiple OIII]1661,66) and [OIII] ($\lambda$4363, and $\lambda$5007) transitions to characterize the physical conditions of the high-ionization zone. This new approach is insensitive to a wide range of n$_{\rm e}$ due to the high critical densities of the OIII] and [OIII] transitions. Applying this technique to six galaxies at z=5-9, we find electron densities up to n$_{\rm e}$$\sim 3\times 10^{5}$ cm$^{-3}$ and temperatures of T$_{\rm e}$ $\sim 20,000$ K in systems at $z>6$. Accounting for these self-consistent densities changes the derived T$_{\rm e}$ and modifies the inferred metallicities by up to 0.29 dex relative to previous estimates. We discuss the reported N/O overabundances in the high-$z$ galaxies from our sample, which arise entirely from the high N$^{3+}$/H$^{+}$ values inferred from NIV] lines. We point out that a T$_{\rm e}$-stratification, in which the N$^{3+}$ zone has a slightly higher T$_{\rm e}$ than T$_{\rm e}$([OIII]), could substantially reduce the inferred N/O. Quantitatively, if T$_{\rm e}$(N$^{3+}$) were 10% higher than T$_{\rm e}$([OIII]), this could induce a systematic overestimation of N$^{3+}$/O$^{2+}$ of nearly 50%. Classical N/O diagnostics such as N$^{+}$/O$^{+}$, due to their critical densities, can significantly impact the inferred N/O abundance in the presence of high-density gas, whereas N$^{2+}$/O$^{2+}$ place these galaxies closer to $z\sim0$ systems in the N/O-O/H plane. Future JWST programs with larger and more diverse samples will be essential to test the universality and robustness of these results.
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All authors Karla Z. Arellano-Córdova, J. Eduardo Méndez-Delgado, Sophia R. Flury, César Esteban, Kathryn Kreckel, Jorge García-Rojas, Fergus Cullen, Leticia Carigi, Christophe Morisset, F. Fabián Rosales-Ortega, Antonio Peimbert, Thomas M. Stanton, Dirk Scholte

Instrumentation and Methods for Astrophysics

Statements of Current States of the Art for Key non-Coronagraphic Technologies for HWO

Paul Scowen, Manuel Quijada, Emily Kan et al. (+7 more)

In preparation for development of both key technologies and instrument concept studies to use those technologies, the Habitable Worlds Observatory Technology Maturation Project Office at the NASA Goddard Space Flight Center has compiled a series of statements of state of the art for those same key technologies. These statements are being provided to the public as exemplars and suggestions for possible future collaboration for those same instrument concept studies, but without mandate, to enable proposing teams to be able to find the technical solutions they need to field a compelling proposal. This information resides in the public domain and is presented without prejudice.
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All authors Paul Scowen, Manuel Quijada, Emily Kan, Michael Hoenk, Prabal Saxena, Oswald Siegmund, Alexander Kutyrev, Massimo Roberto, Randy McEntaffer, Juan Larruquert

Earth and Planetary Astrophysics

TIC-65910228 b / NGTS-38 b, a 180 day transiting warm super-Jupiter

Toby Rodel, Solène Ulmer-Moll, Samuel Gill et al. (+63 more)

We present the discovery of TIC-65910228 b / NGTS-38 b, a giant exoplanet with a radius of $1.081\pm0.047$ R$_\text{J}$ and a mass of $4.78_{-0.37}^{+0.39}$ M$_\text{J}$ on a long-period ($180.52797\pm0.00036$ day), moderately eccentric ($e=0.3086\pm0.010$) orbit transiting a bright (V=$10.230\pm0.020$ mag) metal rich ([Fe/H]=$0.33\pm0.09$, 'dex') F6V-F7V type host star. The planet was initially detected from a single transit in TESS Sector 33. A photometric monitoring campaign of 228 nights with NGTS detected a transit egress of the planet, which together with spectroscopic radial velocity monitoring with CORALIE and HARPS identified an orbital period of ~180.5,d. These radial velocity measurements also showed the mass of the companion to be planetary. Additional transit observations coordinated by the TESS follow-up observing program allowed further confirmation and refinement of this period. With its relatively cool equilibrium temperature of $457\pm11$ K, NGTS-38 b joins a small but growing population of well characterised transiting warm-Jupiters and has one of the longest periods of any discovered to date. The target is situated in the LOPS2 field of the upcoming PLATO mission which will allow for greater refinement of the system parameters and potential for the discovery of additional companions too small and/or too long-period to be seen by TESS or NGTS. NGTS-38 b's bright host star and wide orbital separation make it an attractive target for further study, including potential measurement of its spin-orbit alignment or targeted exomoon/ring searches.
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All authors Toby Rodel, Solène Ulmer-Moll, Samuel Gill, Christopher. A. Watson, Yoshi Nike Emilia Eschen, Alix V. Freckelton, Annelies Mortier, Karen A. Collins, Diana Dragomir, Zahra Essack, Brett Skinner, Niamh Mallaghan, Peter J. Wheatley, David R. Anderson, Ioannis Apergis, Khalid Barkaoui, Matthew P. Battley, Daniel Bayliss, François Bouchy, Edward M. Bryant, Matthew R. Burleigh, Benjamin M. J. Cadell, Samuel J. Carlier, Yann Carteret, Sarah L. Casewell, Alastair B. Claringbold, Jean C. Costes, Benjamin D. R. Davies, Lauren Doyle, Phil Evans, Jorge Fernández Fernández, Emile Fontanet, Edward Gillen, Michael R. Goad, George Harvey, Faith Hawthorn, Katlyn L. Hobbs, Melissa Hobson, Giovanni Isopi, James S. Jenkins, Alicia Kendall, David Kipping, Monika Lendl, Franco Mallia, Christopher Mann, James McCormac, Ernst J.W. de Mooij, Maximiliano Moyano, Arianna Nigioni, Mohammad Odeh, Vera Maria Passegger, Suman Saha, Richard P. Schwarz, Amber Sedgley, Avi Shporer, Abderahmane Soubkiou, Stéphane Udry, Dimitri Veras, Jean. P. Vignes, Steven Villanueva Jr., José I. Vinés, Richard West, Thomas G. Wilson, Hannah L. Worters, Mitchell E. Young, Aldo Zapparata

Astrophysics of Galaxies

Demographics of Wandering Black Holes Powering Off-Nuclear Tidal Disruption Events

Muryel Guolo

The recent discovery of three off-nuclear tidal disruption events (EP240222a, AT2024tvd, and AT2025abcr) - following the first such source, 3XMM J2150$-$05 - reveals a small but robust population of off-nuclear, or `wandering', black holes (WBHs) with masses $M_\bullet > 10^4 M_\odot$. Two demographic trends are already apparent: (i) all events occur in massive, early-type parent galaxies with stellar masses $10.8 \lesssim \log_{10}(M_\star/M_\odot) \lesssim 11.1$; and (ii) events at larger halo-centric radii ($R_{\rm TDE}/R_{200}$) are associated with dwarf satellites ($M_\star \sim 10^7 M_\odot$), while those closer to halo centers lack detected stellar counterparts. Using results from the ROMULUS cosmological simulation, we show that both trends naturally arise from hierarchical galaxy formation. By combining the simulation with empirical constraints on the local galaxy population, we compute the volumetric density of WBHs, $\phi_{\rm WBH}(M_\star)$, finding that it peaks at $\log_{10}(M_\star/M_\odot)=11.10^{+0.05}_{-0.10}$ and that more than half of all WBHs in the local Universe reside in galaxies with $10.7 \lesssim \log_{10}(M_\star/M_\odot) \lesssim 11.2$, explaining (i) and predicting its persistence as the sample grows. We further show that ii), i.e., the observed link between detection of stellar counterparts and $R_{\rm TDE}/R_{200}$, is also expected from tidal stripping. These results demonstrate that off-nuclear TDEs are powered by the population of WBHs long predicted by cosmological simulations.
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Solar and Stellar Astrophysics

Anomaly Hunter for Alerts (AHA): Anomaly Detection in the ZTF Transient Alert Stream

Leyla Iskandarli, Chris J. Lintott, Steve Croft et al. (+2 more)

Modern time-domain surveys produce alert streams at a scale that makes exhaustive manual inspection infeasible, requiring automated methods to identify unusual transients for follow-up. In this work, we present an unsupervised anomaly detection pipeline applied to the ZTF alert stream using the Lasair broker. We define normal objects as SN Ia, SN II, and SN Ib/c. Anomalous objects include (i) more exotic transients (AGN, TDEs, SLSNe, CVs, and nuclear transients) and (ii) supernova-labeled objects, either spectroscopically or by Lasair, with anomalous properties, such as incorrect or absent host associations, or non-supernova-like light curves. Our pipeline consists of three independently trained simple autoencoders operating on distinct alert stream data products: object features, triplet image cutouts, and light curves. Each model is trained on predominantly normal transients, and performance is assessed using the recall of exotic objects and the purity of all anomalous objects across both a spectroscopically classified held-out test set and the live alert stream. In the test set, performance is evaluated at a fixed rank corresponding to the top ten scoring candidates, while in the alert stream it is evaluated using an anomaly threshold defined from test set behavior. Across both settings, the algorithms consistently recover exotic transients and anomalous supernovae among their top-ranked candidates. Over 25 days of live alert stream application, we identify 87 unusual supernova candidates for follow-up. The overlap between anomalies flagged by different autoencoders in the test set is non-existent, and in the alert stream is small, with maximum overlap between any two algorithms being 11 objects. The framework is data-efficient, requiring only a few thousand training examples, making it well suited for early and ongoing application to the Rubin Observatory alert stream.
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All authors Leyla Iskandarli, Chris J. Lintott, Steve Croft, Heloise Stevance, Joshua Weston

High Energy Astrophysical Phenomena

The nearby He-rich superluminous supernova SN 2021bnw during photospheric phases

A. Fiore, A. Kozyreva, L. Yan et al. (+40 more)

Aim. We present and interpret the data of the nearby hydrogen-deficient but helium-rich superluminous supernova SN 2021bnw which reached a magnitude of -20.7 at maximum luminosity in g band. Methods. We discuss the light curves and spectra of SN 2021bnw based on its spectro-photometric follow up exploiting different observational facilities. We reproduce the NIR spectrum of SN 2021bnw with TARDIS to inspect the chemical composition at late photospheric phases and identify helium features. We also use a STELLA model coupling hydrodynamics and radiation transport to constrain the physical parameters of the explosion assmunig a 56Ni+CSM scenario. Results. We suggest that SN 2021bnw was mainly powered by the interaction of the ejecta with a previously lost He-rich circumstellar material, coupled with a central power source. Conclusions. This work expands the data sample of He-rich superluminous supernovae rich (SLSNe Ib) and, assuming a single progenitor scenario, can constrain the masses and the physics of their progenitors.
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All authors A. Fiore, A. Kozyreva, L. Yan, S. Benetti, J. P. Anderson, P. Baklanov, Y. -Z. Cai, E. Cappellaro, T.-W. Chen, N. Elias-Rosa, A. Gal-Yam, M. J. Graham, M. Gromadzki, S. L. Groom, C. P. Gutiérrez, D. Hiramatsu, D. A. Howell, C. Inserra, M. M. Kasliwal, R. Könyves-Tóth, P. Lundqvist, C. McCully, A. Mironov, S. Moran, T. E. Müller-Bravo, M. Newsome, M. Nicholl, P. Ochner, E. Padilla Gonzalez, P. J. Pessi, G. Pignata, F. Ragosta, A. Reguitti, T. M. Reynolds, R. L. Riddle, B. Rusholme, I. Salmaso, S. Schulze, J. Sollerman, L. Tomasella, D. Warshofsky, S. Yang, D. R. Young

Earth and Planetary Astrophysics

Pre-perihelion Emergence of the CN Gas Coma in 3I/ATLAS Temporally and Spatially Resolved by the 7-Dimensional Telescope

Gregory S. H. Paek, Myungshin Im, Mankeun Jeong et al. (+8 more)

We present time-series medium-band (R~20-40) observations of the third interstellar object 3I/ATLAS (C/2025 N1) obtained with the 7-Dimensional Telescope (7DT), enabling spatially resolved monitoring of its gas and dust activity from 2025 July to September. The m400-band image (lambda_c = 400 nm, Delta lambda approx 25 nm) reveals the emergence of pronounced and spatially extended CN emission at heliocentric distances r_h < 3 au. This onset is consistently identified across multiple diagnostics, including a break in the light-curve evolution, excess reflectance, inward expansion of annular excess beyond 10,000-20,000 km, growth of the coma half-light radius from ~11,000 to ~19,000 km, and a rapid rise in the CN production rate Q_CN relative to Af rho. We further separate the CN-emitting and dust-scattered components through two-dimensional surface-brightness fitting into inner (dust) and outer (gas) components. The outer component preserves a nearly constant profile shape, varying only in normalization, implying relatively fast expansion of CN-bearing molecules. Together, these results reveal a transition in the optical from dust-dominated scattering at large heliocentric distances to volatile-driven, gas-dominated activity as 3I/ATLAS enters the inner Solar System. The timing and characteristics of the CN activation resemble the volatile enhancement observed in 2I/Borisov, suggesting that both known active interstellar objects exhibit comparable activation behavior at heliocentric distances of ~2-3 au.
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All authors Gregory S. H. Paek, Myungshin Im, Mankeun Jeong, Hyeonho Choi, Yoonsoo P. Bach, Masateru Ishiguro, Bumhoo Lim, Seo-Won Chang, Ji Hoon Kim, Jooyeon Geem, Willem B. Hoogendam

Astrophysics of Galaxies

STEP survey: III. STEPping stones between the clouds: the star formation history of the Magellanic Bridge

F. Ficara, V. Ripepi, M. Cignoni et al. (+8 more)

The Magellanic Clouds (MCs) offer a unique laboratory for studying galaxy interaction and the evolution of dwarf galaxies. By investigating when and how stars formed, the star formation history (SFH) is a powerful tool to provide constraints for dynamical modeling of the system's past interactions and understand the processes of stripping and triggered star formation in tidally influenced environments. We aim to reconstruct the SFH of the Magellanic Bridge, the gaseous and stellar stream connecting the two Clouds. We used data from the deep optical STEP survey, which covers 54 $\mathrm{deg\, {^{2}}}$ across the Small Magellanic Cloud (SMC) and the Bridge, reaching stars below the oldest main sequence turnoff at the distance of the MCs. We applied the synthetic color-magnitude diagram (CMD) technique to 14 deg$^2$ of STEP data. We constructed two libraries of synthetic stellar populations based on the PARSEC-COLIBRI and BaSTI stellar evolutionary models, with metallicities in the range $-2.0\leq[$Fe/H$]\leq0$ across the whole Hubble time. We find a clear peak of recent star formation $\sim100$ Myr ago in the Magellanic Bridge, which becomes increasingly pronounced toward the SMC. The low metallicity of this population suggests that it formed from gas stripped from the SMC during its most recent close encounter with the LMC. In the eastern part of the Bridge (LMC side), the star formation peaks at earlier times, around 10 Gyr and 2 Gyr ago. We estimate a total stellar mass in the Bridge of $ (5.1 \pm 0.2) \times 10^5 M_\odot$ and a present-day stellar metallicity of $[$Fe/H$]\sim-0.6$ dex, close to SMC value.
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All authors F. Ficara, V. Ripepi, M. Cignoni, M. Gatto, M. Marconi, M. Tosi, M. Bellazzini, E. K. Grebel, M. R. Cioni, C. Tortora, A. Mercurio

Instrumentation and Methods for Astrophysics

Observations of Binary Stars with the 1.3-m Devasthal Fast Optical Telescope Using Speckle Interferometry: An Attempt

Km Nitu Rai, Arjun Dawn, Neelam Panwar et al. (+3 more)

We present a feasibility study of implementing optical interferometry and speckle techniques with the 1.3-m Devasthal Fast Optical Telescope (DFOT) at Aryabhatta Research Institute of Observational Sciences (ARIES), which is currently dedicated to photometric observations. Using the sCMOS camera at the DFOT backend, we perform interferometric speckle observations of six binary stars. Standard Speckle Interferometry algorithms are applied to analyze the recorded speckle images. While this study does not aim to achieve the diffraction limit of DFOT or address a full science-driven resolution case, it serves as a crucial testbed for instrumentation, data acquisition, and analysis of Speckles with DFOT. Although the individual speckle patterns exhibit significant positional variations from frame to frame, the Speckle Interferometry analysis successfully recovers the characteristic three-peak structure of the wide binaries, allowing their relative separations and position angles to be determined, demonstrating the viability of the approach. The measured angular relative separations of $\gamma$ Leo, $\gamma$ Vir, and $\zeta$ Her are $4.744'' \pm 0.012''$, $3.387'' \pm 0.027''$, and $1.582'' \pm 0.026''$, respectively, with corresponding projected position angles of $126.94^{\circ} \pm 0.14^\circ$, $171.57^{\circ} \pm 0.33^\circ$, and $81.06^{\circ} \pm 0.91^\circ$. These measurements are consistent with previously reported values in the literature, which provides strong motivation for more systematic observations and future implementation of optical interferometry techniques at meter-class telescopes.
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All authors Km Nitu Rai, Arjun Dawn, Neelam Panwar, Jeewan C Pandey, Subrata Sarangi, Prasenjit Saha

Earth and Planetary Astrophysics

Gaps and Rings: A Near-Universal Trait of Extended Protoplanetary Discs

Quincy Bosschaart, Osmar M. Guerra-Alvarado, Nienke van der Marel et al. (+1 more)

Substructures such as rings, gaps, and cavities are commonly observed in protoplanetary discs and are thought to play a key role in dust evolution and planet formation. However, a fraction of the extended discs (68% dust radii > 30 AU) in nearby star-forming regions remain unresolved, leaving their substructure content uncertain and thereby limiting our understanding of dust evolution and the initial conditions for planet formation across the full disc population. We aim to investigate the presence of substructures in previously unresolved, extended discs to assess whether all extended protoplanetary discs in the Solar neighbourhood exhibit substructures. We present new high-resolution ($\sim$0.12") ALMA Band 6 continuum observations at 1.33 mm of 26 previously unresolved, extended discs within 200 pc, completing the high-resolution sample of extended discs in Taurus, Ophiuchus, Chamaeleon, Lupus, Upper Scorpius, Upper Centaurus-Lupus and Lower Centaurus-Crux. We analyse radial intensity profiles using Frankenstein and Galario to detect substructures. Seventeen discs show clear substructures, while nine appear compact and structureless, smooth or ambiguous due to inclination or possible binarity/late-stage infall. We detect $^{12}$CO J=2-1 emission in 15 discs, with extended emission in four. Combined with literature data, our complete sample of 730 protoplanetary discs reveals that nearly all extended discs exhibit substructures, $\sim$91% detected in the full sample, and up to $\sim$98% when correcting for high-inclination systems where substructures may be hidden. Substructures are a near-universal feature of extended protoplanetary discs. They are more commonly detected in larger, massive discs and around higher-mass stars, and structured discs retain their dust mass over time. This supports the scenario in which dust traps, possibly induced by giant planets, shape disc morphologies.
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All authors Quincy Bosschaart, Osmar M. Guerra-Alvarado, Nienke van der Marel, Gijs D. Mulders

Solar and Stellar Astrophysics

The Effect of Gravitational Stratification on Kink Oscillations in Curved Coronal Loops

Mingzhe Guo, Bo Li and Mijie Shi

Kink oscillation frequency is a key parameter for coronal seismology. It is still unclear how gravitational stratification affects the kink frequency in curved coronal loops. This work aims to investigate the effect of gravitational stratification on the frequency of kink oscillations in curved coronal loops and discuss their seismological potential. We conduct numerical computations within the ideal MHD framework to study different kink polarizations and harmonics in a curved, gravitationally stratified coronal loop. The oscillation frequencies derived from the Lagrangian displacement are compared with the WKB approximation. For the vertically polarized fundamental mode, the oscillation frequency deviates from the WKB approximation by about 18% in the current numerical setup. Nevertheless, the oscillation frequency closely matches the local Alfvén frequency near the loop apex. On the other hand, the frequency of the horizontally polarized fundamental mode exhibits only a 7% deviation in our current model from the WKB approximation and closely matches the local Alfvén frequency near one quarter of the loop. For the first overtones, the frequencies for both polarizations can be well described by the WKB approximation. The frequency of vertically polarized fundamental kink modes can be predicted by the local Alfvén frequency near the loop apex. In contrast, the WKB approximation remains highly reliable for estimating the frequency of horizontally polarized fundamental modes and first overtones, which is also well described by the local Alfvén frequency near one quarter of the loop. These results therefore pave the way for spatially dependent coronal seismology, enabling, e.g., the probing of magnetic field strength at different locations along a coronal loop.
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Astrophysics of Galaxies

Upper limit on HF(1-0) absorption in a dusty star-forming galaxy at $z = 6$: Constraints on early fluorine enrichment

Akiyoshi Tsujita, Chiaki Kobayashi, Yuki Yoshimura et al. (+10 more)

Wolf-Rayet (WR) stars have recently attracted attention as possible drivers of early chemical enrichment, including the production of fluorine, whose nucleosynthetic origin remains debated. To test the contribution of massive stars to fluorine production in the early Universe, we conducted Atacama Large Millimeter/submillimeter Array Band 5 spectroscopy of the HF(1-0) absorption line toward a dusty star-forming galaxy at $z=6.024$. This galaxy has a known gas-phase metallicity and is too young for low-mass AGB stars to have contributed significantly, providing a clean environment to isolate massive-star yields. We do not detect significant HF absorption ($\sim2\sigma$) and derive a conservative 5$\sigma$ upper limit of $N_\mathrm{HF}/N_\mathrm{H_2} < 2.2\times10^{-9}$. This limit is about an order of magnitude below typical local measurements, indicating inefficient fluorine enrichment $\sim0.9$ Gyr after the Big Bang. Comparison with chemical evolution models shows that our constraint is consistent with scenarios without WR yields at this epoch. Expanding the sample of HF absorption measurements in high-redshift galaxies with well-characterized metallicities will be crucial for tracing the onset of WR enrichment and fluorine production across cosmic time.
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All authors Akiyoshi Tsujita, Chiaki Kobayashi, Yuki Yoshimura, Kotaro Kohno, Ken-ichi Tadaki, Fumiya Maeda, Hideki Umehata, Shuo Huang, Bunyo Hatsukade, Fumi Egusa, Kana Morokuma-Matsui, Yoichi Tamura, Yuri Nishimura