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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 18 November

Astrophysics of Galaxies

Mixing between AGN winds and ISM clouds produces luminous X-ray emission

Samuel Ruthven Ward, Tiago Costa, Chris M. Harrison et al. (+1 more)

Active galactic nuclei (AGN) drive powerful, multiphase outflows that are thought to play a key role in galaxy evolution. The hot, shocked phase of these outflows ($T \gtrsim 10^{6} \rm{\ K}$) is expected to dominate the energy content, but is challenging to observe due to its long cooling time and low emissivity. The cool phase ($T \lesssim 10^{4} \rm{\ K}$) is easier to detect observationally, but it traces a less energetic outflow component. In prior simulations of the interaction between an energy-driven AGN outflow and a clumpy ISM, we found that mixing between hot wind and cool ISM clouds produces a new, highly radiative, phase at $T \approx 10^{6-7} \rm{\ K}$ which fuels the formation of a long-lived ($\geq 5\ \rm{Myr}$) cool outflow. We investigate the X-ray emission generated by thermal Bremsstrahlung and high-ionisation metal line emission in this mixing phase, finding that it could contribute significantly to the X-ray output of the outflow. This mixing-induced X-ray emission is strongest in the part of the outflow propagating equatorially through the disc, and is extended on scales of $D\simeq 3-4\ \rm{kpc}$. For quasar luminosities of $L_{\rm{AGN}}\simeq 10^{45-46}\rm{\ erg\ s^{-1}}$, the resulting X-ray luminosity is equivalent to that expected from star formation rates $\rm{SFR}\simeq 10-200\ \rm{M_\odot\ yr^{-1}}$, showing that it could be an important source of soft X-rays in AGN host galaxies. Our results suggest that this extended emission could be resolvable in local quasars ($z\lesssim 0.11$) using high spatial-resolution X-ray observatories such as Chandra, or proposed missions such as AXIS and Lynx.
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All authors Samuel Ruthven Ward, Tiago Costa, Chris M. Harrison, Vincenzo Mainieri

Astrophysics of Galaxies

Localized Deviations from the CO-PAH Relation in PHANGS-JWST Galaxies: Faint PAH Emission or Elevated CO Emissivity?

Jaeyeon Kim, Adam K. Leroy, Karin Sandstrom et al. (+25 more)

Polycyclic aromatic hydrocarbon (PAH) emission is widely used to trace the distribution of molecular gas in the interstellar medium, exhibiting a tight correlation with CO(2-1) emission across nearby galaxies. Using PHANGS-JWST and PHANGS-ALMA data, we identify localized regions where this correlation fails, with CO flux exceeding that predicted from 7.7$\mu$m PAH emission by more than an order of magnitude. These outlier regions are found in 20 out of 70 galaxies and are located in galaxy centers and bars, without signs of massive star formation. We explore two scenarios to explain the elevated CO-to-PAH ratios, which can either be due to suppressed PAH emission or enhanced CO emissivity. We examine PAH emission in other bands (3.3$\mu$m and 11.3$\mu$m) and the dust continuum dominated bands (10$\mu$m and 21$\mu$m), finding consistently high CO-to-PAH (or CO-to-dust continuum) emission ratios, suggesting that 7.7$\mu$m PAH emission is not particularly suppressed. In some outlier regions, PAH sizes and spectral energy distribution of the radiation differ slightly from nearby control regions with normal CO-to-PAH ratios, though without a consistent trend. We find that the outlier regions show higher CO velocity dispersions ($\Delta v_{\mathrm{CO}}$). This increase in $\Delta v_{\mathrm{CO}}$ lowers CO optical depth and raises its emissivity for a given gas mass. Our results favor a scenario where shear along the bar lanes and shocks at the bar ends elevate CO emissivity, leading to the breakdown of the CO-PAH correlation. Future JWST spectroscopy and deep ALMA observations of CO isotopologues will provide critical tests of this scenario.
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All authors Jaeyeon Kim, Adam K. Leroy, Karin Sandstrom, Sharon E. Meidt, Yu-Hsuan Teng, Miguel Querejeta, Eva Schinnerer, Susan E. Clark, Ryan Chown, Simon C. O. Glover, Daniel A. Dale, Dalya Baron, Jessica Sutter, Ashley T. Barnes, Jakob den Brok, Rupali Chandar, I-Da Chiang, Oleg V. Egorov, Kathryn Grasha, Ralf S. Klessen, Kathryn Kreckel, Eric W. Koch, Hannah Koziol, Lukas Neumann, Hsi-An Pan, Sophia K. Stuber, Tony D. Weinbeck, Thomas G. Williams

Solar and Stellar Astrophysics

V570 Per: Characterization of a Benchmark Eclipsing Binary

Gökhan Yücel, Neslihan Alan, Timothy Banks et al. (+3 more)

This study presents a comprehensive analysis of the detached binary system V570\,Per through combined photometric, spectroscopic, and astrometric observations. By disentangling the composite spectra, precise fundamental parameters and detailed chemical abundances were determined for both stars. The primary component has a mass of $1.4569_{-0.0100}^{+0.0094}$ $M_{\odot}$, a radius of $1.543_{-0.009}^{+0.012}$ $R_{\odot}$, an effective temperature of $6556_{-26}^{+64}$ K, and a metallicity of $+0.18_{-0.01}^{+0.03}$ dex, while the secondary has a mass of $1.3579_{-0.0089}^{+0.0094}$ $M_{\odot}$, a radius of $1.377_{-0.015}^{+0.013}$ $R_{\odot}$, an effective temperature of $6468_{-21}^{+32}$ K, and a metallicity of $+0.15_{-0.01}^{+0.02}$ dex. The system is estimated to be $577_{-60}^{+60}$ Myr old with a synchronized orbit. The available O-C data imply a minimum mass of 0.57 $M_{\odot}$ or 0.11 $M_{\odot}$ for the third body, corresponding to eccentric and circular orbits, respectively. MESA evolutionary models indicate that the primary will fill its Roche lobe and begin mass transfer to the secondary in about 2.8 Gyr, whereas the secondary will reach the terminal-age main sequence in approximately 3.2 Gyr. The chemical composition of both stars shows remarkable consistency, confirming their common origin, except for calcium, which is significantly enhanced in the primary. Line measurements support this difference and are therefore interpreted as an intrinsic abundance variation rather than an artifact of the analysis. The overall solar-rich metallicity, combined with a relatively low $\alpha$-element content, links V570\,Per to the Galactic thin-disk population. In addition, Galactic orbit analyses of open clusters in the solar neighborhood have revealed that the V570\,Per system may have originated from the Melotte 25 open cluster.
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All authors Gökhan Yücel, Neslihan Alan, Timothy Banks, Remziye Canbay, Volkan Bak{\i}ş, Selçuk Bilir

Solar and Stellar Astrophysics

Delayed Wind Onset in Pa 30, the Remnant of Type Iax SN 1181

Takatoshi Ko, Ryosuke Hirai, Taiga Sasaoka et al. (+1 more)

Pa 30 is the recently identified remnant of the historical supernova SN 1181, likely a Type Iax event, and a nebula surrounding the central white dwarf launching a fast wind ($\sim10^9~\cm~\s^{-1}$) is observed in optical and infrared bands. X-ray observations show that this wind collides with the surrounding material and produces a termination shock, and the observed extent of the shock indicates that the wind started blowing centuries after 1181 A.D. rather than immediately after the SN explosion. We propose that the wind is triggered by delayed ignition of fallback carbon-rich material on the WD surface and investigate the conditions that reproduce such delayed ignition. We show that producing delays of several centuries requires a relatively hot post-explosion WD core with a temperature $T_c \simeq 6\times10^8~\mathrm{K}$. This supports the pure-deflagration progenitor scenario for Type Iax SN 1181, which implies the presence of a He star companion inside Pa~30; we also discuss why such a potential He star has not been detected and its prospects for discovery by future observations.
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All authors Takatoshi Ko, Ryosuke Hirai, Taiga Sasaoka, Toshikazu Shigeyama

High Energy Astrophysical Phenomena

Forecasting properties of detectable massive binary black hole mergers in the era of space based gravitational-wave detectors

Sourabh Magare, Abhinav Roy, Shasvath J. Kapadia et al. (+2 more)

Gravitational waves (GWs) from massive black hole (MBH) mergers will provide a novel way to probe the high-redshift universe and are key to understanding galactic dynamics and evolution. In this work, we analyze MBH mergers, their GW signals and detectability, as well as their population properties, using the cosmological hydrodynamical simulation - NINJA Simulation Suite. We discuss the effect of resolution and finite volume on the black hole mass function (BHMF), which in turn limits the mergers associated with low mass black holes, $M_{BH} \lesssim 10^{6.5} M_\odot$. We find the upper limit on the total mass of the MBH binaries detectable by LISA to be $\sim 10^{8.4} M_\odot$. We also find that adding time delays pertaining to dissipative processes like dynamical friction and stellar hardening during the final stages of the inspiral for which the simulation lacks sufficient resolution to model, considerably shifts the peak of redshift distribution of detectable binaries from $z\sim0.5$ to $z\sim0.1$. Time delays reduce the number of detectable GW events but on the other hand their signal-to-noise is increased. From the observational point of view, we find a strong correlation between the SFR and $L_{\rm bol}$ at high redshifts for the detectable LISA binaries. This may prove to be a future application in the coincident observation of MBH binaries by GW and electromagnetic observations.
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All authors Sourabh Magare, Abhinav Roy, Shasvath J. Kapadia, Nishikanta Khandai, R. Srianand

Earth and Planetary Astrophysics

Starlight-driven flared-staircase geometry in radiation hydrodynamic models of protoplanetary disks

Prakruti Sudarshan, Mario Flock, Alexandros Ziampras et al. (+2 more)

Protoplanetary disks observed in millimeter continuum and scattered light show a variety of substructures. Various physical processes in the disk could trigger such features – one of which that has been previously theorized for passive disks is the thermal wave instability – the flared disk may become unstable as directly illuminated regions puff up and cast shadows behind them. This would manifest as bright and dark rings, and a staircase-like structure in the disk optical surface. We provide a realistic radiation hydrodynamic model to test the limits of the thermal wave instability in irradiated disks. We carry out global axisymmetric 2D hydrostatic and dynamic simulations including radiation transport with frequency-dependent ray-traced irradiation and flux-limited diffusion (FLD). We found that starlight-driven shadows are most prominent in optically thick, slow cooling disks, shown by our models with high surface densities and dust-to-gas ratios of sub-micron grains of 0.01. We recover that thermal waves form and propagate inwards in the hydrostatic limit. In contrast, our hydrodynamic models show bumps and shadows within 30 au that converge to a quasi-steady state on several radiative diffusion timescales – indicating a long-lived staircase structure. We find that existing thermal pressure bumps could produce and enhance this effect, forming secondary shadowing downstream. Hydrostatic models with self-consistent dust settling instead show a superheated dust irradiation absorption surface with a radially smooth temperature profile without staircases. We conclude that one can recover thermally induced flared-staircase structures in radiation hydrodynamic simulations of irradiated protoplanetary disks using flux-limited diffusion. We highlight the importance of modeling dust dynamics consistently to explain starlight-driven shadows.
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All authors Prakruti Sudarshan, Mario Flock, Alexandros Ziampras, David Melon Fuksman, Tilman Birnstiel

Cosmology and Nongalactic Astrophysics

The first data-driven bounds on the quantum decoherence of inflationary gravitational waves

Jessie de Kruijf, Giacomo Galloni and Nicola Bartolo

The (large-scale) structures we observe in the Universe are classical, but within the inflationary scenario they do originate from quantum fluctuations. This leads to the question: ”How did this quantum-to-classical transition occur?”. A potential explanation is quantum decoherence due to interactions between different fields present during inflation. The tensor modes (i.e. primordial gravitational waves) can interact with a scalar sector, causing their quantum decoherence to occur and inducing a change in the gravitational wave (GW) background. The power spectrum of these GWs can be constrained using the upper bounds found by Planck, BICEP/Keck Array, LIGO-Virgo-KAGRA, Big Bang Nucleosynthesis, and the Pulsar Timing Array detections. These impose constraints on the interaction between the fields. We find that the observational upper bounds mainly constrain scenarios with a strong interaction, especially if the interaction is also strongly time dependent. Furthermore, we find which observationally allowed scenarios have not completed decoherence by the end of inflation, thus possibly leaving quantum signatures in the GW background. Lastly, we show that, interestingly enough, there are decoherence scenarios corresponding to the signal observed by PTA experiments. This highlights the importance of the quantum decoherence effect on GWs.
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Cosmology and Nongalactic Astrophysics

Constraining the Nature of Dark Matter from Tidal Radii of Cluster Galaxy Subhalos

Barry T. Chiang, Isaque Dutra and Priyamvada Natarajan

Gravitational lensing by galaxy clusters provides a powerful probe of the spatial distribution of dark matter and its microphysical properties. Strong and weak lensing constraints on the density profiles of subhalos and their truncation radii offer key diagnostics for distinguishing between collisionless cold dark matter (CDM) and self-interacting dark matter (SIDM). Notably, in the strongly collisional SIDM regime, subhalo core collapse and enhanced mass loss from ram-pressure stripping predict steeper central density slopes and more compact truncation radii–features that are directly testable with current lensing data. We analyze subhalo truncation in eight lensing clusters (Abell 2218, 383, 963, 209, 2390, and MACS J0416.1, J1206.2, J1149.6) that span the redshift range <$z_\text{spec}$>$ \simeq 0.17$-$0.54$ with virial masses $M_{200} \simeq0.41$-$2.2\times 10^{15}$ M$_\odot$ to constrain SIDM versus CDM. Our results indicate that the outer spatial extents of subhalos are statistically consistent with CDM, corroborated by redshift- and mass-matched analogs from the Illustris-TNG simulations. We conclude that the tidal radii of cluster galaxy subhalos serve as an important and complementary diagnostic of the nature of dark matter in these violent, dense environments.
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Earth and Planetary Astrophysics

Modelling the Milky Way's exoplanet population based on cosmological galaxy simulations

Chloé Padois, Daniel del Ser, Friedrich Anders et al. (+7 more)

In this paper we aim to simulate realistic exoplanet populations across different regions of the MW by combining state-of-the-art cosmological simulations of our Galaxy with exoplanet formation models and observations. We model the exoplanet populations around single stars, using planet occurrence rates and multiplicity depending on stellar mass, metallicity, and planet type, and assign them physical parameters such as mass and orbital period. Focussing first on the solar vicinity, we find mostly metallicity-driven differences in the distributions of non-hosting and planet-hosting single stars. In our simulated solar neighbourhood, 52.5% of all planets are Earth-like (23% of them located in the Habitable Zone), 44% are super-Earths/Neptunes, and 3.5% are giant planets. A comparison with the census of Kepler exoplanets and candidates shows that, when taking into account the most relevant selection effects, we obtain a similar distribution of exoplanets compared to the observed population. However, we also detect significant differences in the exoplanet and host star distributions (e.g. more planets around F-type and red-giant stars compared to observations) that we attribute mostly to a too strong recent star formation and a too large disc scale height in the simulation, as well as to some caveats in our exoplanet population synthesis that will be addressed in future work. Extending our analysis to other regions of the simulated MW and to other simulated galaxies, we find that the relative percentages of planet types remain largely consistent as long as the simulated galaxy matches the morphology and mass of the MW. We have created a fast and flexible framework to produce exoplanet populations based on MW-like simulations that can easily be adapted to produce predictions for the yields of future exoplanet detection missions. (abridged)
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All authors Chloé Padois, Daniel del Ser, Friedrich Anders, João A. S. Amarante, Hélio D. Perottoni, Thomas Hajnik, Diogo Souto, Nayara I. Feliciano-Souza, Daisuke Kawata, Eder Martioli

Astrophysics of Galaxies

Transferring Data from a Voronoi Mesh to an Adaptive Cartesian Grid in Pursuit of Self-consistent Top-down Star Formation

Sean C. Lewis, Brooke Polak, Mordecai-Mark Mac Low et al. (+5 more)

Unstructured Voronoi mesh simulations offer many advantages for simulating self-gravitating gas dynamics on galactic scales. Adaptive mesh refinement (AMR) can be a powerful tool for simulating the details of star cluster formation and gas dispersal by stellar feedback. Zooming in from galactic to local scales using the star cluster formation simulation package Torch requires transferring simulation data from one scale to the other. Therefore, we introduce VorAMR, a novel computational tool that interpolates data from an unstructured Voronoi mesh to an AMR Cartesian grid. VorAMR is integrated into the Torch package, which integrates the FLASH AMR magnetohydrodynamics code into the Astrophysical Multipurpose Software Environment. VorAMR interpolates data from an AREPO simulation to a FLASH AMR grid using a nearest-neighbor particle scheme, which can then be evolved within the Torch package, representing the first ever transfer of data from a Voronoi mesh to an AMR Cartesian grid. Interpolation from one numerical representation to another results in an error of a few percent in global mass and energy conservation, which could be reduced with higher-order interpolation of the Voronoi cells. We show that the postinterpolation Torch simulation evolves without numerical abnormalities. A preliminary Torch simulation is evolved for 3.22 Myr and compared to the original AREPO simulation over the same time period. We observe similarly distributed star cluster formation between the two simulations. More compact clusters are produced in the Torch simulation as well as 2.3 times as much stellar material as in AREPO, likely due to the differences in resolution.
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All authors Sean C. Lewis, Brooke Polak, Mordecai-Mark Mac Low, Stephen L. W. McMillan, Claude Cournoyer-Cloutier, Hui Li, Maite J. C. Wilhelm, Simon Portegies Zwart

Solar and Stellar Astrophysics

Massive runaway star HD 254577: the pre-supernova binary companion to the progenitor of the supernova remnant IC 443

B. Dinçel, G. Payl{\i}, S. K. Yerli et al. (+9 more)

The secondaries of the massive binary systems can be found as runaway stars after being ejected due to the supernova (SN) of the more massive component. We search for such stars inside the supernova remnants (SNRs), where a recent SN is guaranteed to have happened. In this paper, we present the massive runaway star HD~254577 as the pre-supernova binary companion to the progenitor of the supernova remnant IC~443 and the neutron star (NS) CXOU~J61705.3$+$222127. We performed spectroscopic observations of the runaway star and specified its atmospheric parameters. Together with the precise Gaia DR3 astrometry and photometry, we identified the possible birth origin of the runaway star, and by isochrone fitting, we determined the progenitor mass. From the Gaia DR3 proper motions, we specified the possible explosion sites and calculated the neutron star (NS) velocity. HD~254577 is a hot and evolved star with an effective temperature of $24000\pm1000$ K (B0.5II) and a surface gravity of $\log({g~\rm[cm/s^2]})=2.75\pm0.25$. It is probably a single star with a peculiar 3-D velocity of $31.3^{+1.2}_{-0.9}$ km~s$^{-1}$, lying at a heliocentric distance of $1701^{+55}_{-54}$ pc. The cometary tail of the NS implies that it is moving away from the same site as the runaway star. From the flight trajectories, we calculated that the NS has typical pulsar velocities such as $254-539$ km~s$^{-1}$ at a distance of $1.7$ kpc for $10-20$ kyr ages. Together with the blue-only shifted interstellar medium lines on its spectrum, HD~254577 must be the pre-supernova binary companion to the progenitor of IC~443. By identifying the pre-supernova companion and the possible parent cluster, we showed that the progenitor zero-age main sequence mass is high: $31-64$ M$_\odot$. We also discuss the expansion dynamics of the SNR due to the highly off-centered explosion site.
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All authors B. Dinçel, G. Payl{\i}, S. K. Yerli, A. Ankay, R. Neuhäuser, M. Mugrauer, S. Sheth, S. Buder, S. Hüttel, F. Edelmann, K-U. Michel, J. Bätz

Instrumentation and Methods for Astrophysics · Cross-listed from cs.CL

Encoding and Understanding Astrophysical Information in Large Language Model-Generated Summaries

Kiera McCormick and Rafael Martínez-Galarza

Large Language Models have demonstrated the ability to generalize well at many levels across domains, modalities, and even shown in-context learning capabilities. This enables research questions regarding how they can be used to encode physical information that is usually only available from scientific measurements, and loosely encoded in textual descriptions. Using astrophysics as a test bed, we investigate if LLM embeddings can codify physical summary statistics that are obtained from scientific measurements through two main questions: 1) Does prompting play a role on how those quantities are codified by the LLM? and 2) What aspects of language are most important in encoding the physics represented by the measurement? We investigate this using sparse autoencoders that extract interpretable features from the text.
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Cosmology and Nongalactic Astrophysics

Equilateral non-Gaussian Bias at the Field Level

Divij Sharma, James M. Sullivan, Kazuyuki Akitsu et al. (+1 more)

Primordial non-Gaussianity (PNG) is a common prediction of a wide class of inflationary models. Equilateral-type PNG, generically predicted by single-field inflationary models with higher-derivative interactions, imprints subtle but measurable signatures on the large-scale distribution of matter. An important parameter of these imprints is the PNG-induced bias coefficient $b_\psi$, which quantifies how the abundance and clustering of dark matter halos and galaxies respond to mode coupling in the initial conditions. Measuring $b_\psi$ is important for constraining equilateral PNG, yet it is notoriously challenging due to its degeneracy with Gaussian scale-dependent bias contributions. In this work, we present the first precision measurements of equilateral $b_\psi$ for dark matter halos using effective field theory at the field level. We show that this approach disentangles PNG effects from those of the Gaussian bias by virtue of noise variance cancellation. We compare our results with the phenomenological predictions based on the Peak-Background Split model, finding some agreement at the qualitative level on the redshift and mass dependence, but poor agreement at the quantitative level. We present a fitting formula for $b_\psi$ as a function of the linear bias, which can be used to set priors in PNG searches with ongoing and future galaxy surveys.
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All authors Divij Sharma, James M. Sullivan, Kazuyuki Akitsu, Mikhail M. Ivanov

Cosmology and Nongalactic Astrophysics

Closing in on $\alpha$-attractors

Laura Iacconi, Sukannya Bhattacharya, Matteo Fasiello et al. (+1 more)

Recent observations of cosmic microwave background (CMB) anisotropies combined with large-scale structure may point towards higher values of the scalar spectral index, $n_s$. This puts previously preferred inflationary models, such as $\alpha$-attractors, in tension with the new measurements. Pending a resolution of the tension between BAO parameters as determined by CMB datasets and those determined by DESI, we explore in this work the large-$n_s$ regime of $\alpha$-attractor T-models. We show that some T-models can self-consistently produce an extended reheating stage with a stiff equation of state $(\bar w>1/3)$, which allows values for $n_s$ closer to unity. We employ constraints from P-ACT-LB-BK18 data to illustrate what large-$n_s$ observations might imply for T-models with monomial potentials. We show that the $n_s$ measurement yields an upper limit on $\alpha$ that is stronger than the one from the tensor-to-scalar ratio only. We find that $n_s$ is maximised for $\alpha\sim1$, therefore the seven Poincaré models are well placed to deliver large $n_s$. However, the ability of a stiff reheating stage to increase the compatibility of T-models with large-$n_s$ measurements saturates as $\bar{w}\to1$. Thanks to this effect, we establish that the largest $n_s$ that monomial T-models can produce is $n_s=0.9682$. T-models are therefore highly predictive in the large-$n_s$ regime and our result provides, under the assumption of perturbative reheating, a benchmark which could be used in the future to rule out monomial T-models.
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All authors Laura Iacconi, Sukannya Bhattacharya, Matteo Fasiello, David Wands

Cosmology and Nongalactic Astrophysics

High-resolution weak lensing mass mapping from DES-Y3 data using diffusion-based prior

Supranta S. Boruah, Michael Jacob, Bhuvnesh Jain et al. (+2 more)

High-resolution mapping of cosmic mass distribution is essential for a variety of astrophysical applications including understanding cosmic structure formation, and galaxy formation and evolution. However dark matter is not directly observed and therefore we need advanced methods for solving inverse problems to reconstruct the underlying cosmic matter distribution. Here, we train a generative diffusion model and use it in the Diffusion Posterior Sampling (DPS) framework to reconstruct mass maps from Dark Energy Survey-Year 3 (DES-Y3) weak gravitational lensing data at high (1 arcminute) resolution. We show that the standard DPS results are biased, but they can be easily corrected by scaling the log-likelihood score during the diffusion process, yielding unbiased results with proper uncertainty quantification. The resulting mass maps reveal cosmic structures with enhanced detail, opening the door for improved astrophysical studies using the obtained mass maps.
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All authors Supranta S. Boruah, Michael Jacob, Bhuvnesh Jain, Riya Maiya, Raghav Venkataramanan

Astrophysics of Galaxies

RIOJA. The dusty outflows and density-complex interstellar medium in the N-enhanced lensed galaxy RXCJ2248-ID at z=6.1

A. Crespo Gómez, Y. Tamura, L. Colina et al. (+19 more)

We present an analysis on the kinematics and physical properties of the ionized gas in the lensed galaxy RXCJ2248-ID at z=6.1 based on high-resolution JWST NIRSpec/IFU data in combination with ALMA observations. Our analysis reveals a high electron temperature ($T_e$$\sim$30000K) in the ionized gas, independent of the ionization level. We measure a wide range in the electron densities derived from [OIII]$\lambda$5008/[OIII]88$\mu$m and [ArIV]$\lambda$4713/[ArIV]$\lambda$4742 ratios (log($n_e$[cm$^{-3}$])$\sim$2.7-3.8), and previous values (log($n_e$[cm$^{-3}$])>4.8) based on high-ionization rest-UV emission lines. The ionized gas appears to be clumpy with a low filling factor ranging from about 10% to 0.2% for the low- and high-density clouds. In addition, we observe a very complex ISM kinematic structure, with the presence of two distinct broad and a very-broad components (FWHM$\sim$210 and $\sim$1000 kms$^{-1}$) in addition to the systemic one (FWHM$\sim$60 kms$^{-1}$) in [OIII]$\lambda$5008 and H$\alpha$. These broad components are heavily extinct (A$_V$$\sim$1.5 and 2.5, respectively), based on their Balmer decrements, while the gas associated to the narrow component is consistent with no extinction. The maximal velocities of these outflows ($\sim$115-500kms$^{-1}$) are such that a fraction of the total outflowing gas (0.16-2.1$\times$10$^7$M$_\odot$) could escape into the IGM. The rest of the gas will fall back to the central regions, being available for additional star formation episodes. The presence of dusty outflows and clumpy (i.e., low filling factor) ISM give support to the Attenuation-Free scenario proposed to explain the high-z UV-bright compact galaxies such as RXCJ2248-ID. On the other hand, the high densities in the ISM, together with the high SFR surface brightness, and the amount of returning outflowing mass give support to the Feedback-Free Starburst scenario.
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All authors A. Crespo Gómez, Y. Tamura, L. Colina, J. Álvarez-Márquez, T. Hashimoto, R. Marques-Chaves, Y. Nakazato, C. Blanco-Prieto, K. Sunaga, L. Costantin, A. K. Inoue, A. Hamada, S. Arribas, D. Ceverino, M. Hagimoto, K. Mawatari, W. Osone, Y. Sugahara, Y. Harikane, M. M. Lee, A. Taniguchi, H. Umehata

Instrumentation and Methods for Astrophysics

A socio-demographic study of the exoplanet direct imaging community II

Lucie Leboulleux, Niyati Desai, Daniel Echeverri et al. (+9 more)

Recognizing and addressing under-representation, exclusion, and problematic behavior within astronomy and astrophysics is crucial. In 2019, a survey was conducted at the Spirit of Lyot conference to evaluate the socio-demographics and well-being of the exoplanet and disk imaging community. This paper presents the results of a second survey, conducted at the 2022 Spirit of Lyot conference in Leiden, aiming to improve the evaluation of the community, expand diversity-related questions, and monitor the evolution of metrics since 2019. Sent to all participants, the survey received 96 responses. It measures respondents' visibility at conferences, recognition through publications and projects, experiences of disrespect or inappropriate behaviors as victims or witnesses, and identification as allies of minorities. These aspects were analyzed with respect to job position, expatriation, gender, belonging to another under-represented group (ethnicity, disability, sexual orientation), and parenthood.
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All authors Lucie Leboulleux, Niyati Desai, Daniel Echeverri, Evangelia Kleisioti, Lorenzo Konig, Mathilde Malin, Elisabeth Matthews, Saavidra Perera, Schuyler Wolff, Elodie Choquet, Elsa Huby, Garima Singh

Earth and Planetary Astrophysics

A search for transit timing variations in the transiting hot Jupiter systems HIP 65, NGTS-6, NGTS-10 and WASP-173

A. W. Griffiths, J. Southworth, L. Alegre et al. (+30 more)

Hot Jupiters are Jupiter-mass planets with orbital periods of less than ten days. Their short orbital separations make tidal dissipation within the stellar host especially efficient, potentially leading to a measurable evolution of the orbit. One possible manifestation of this is orbital decay, which presents itself observationally through variations in the orbital period and thus times of transit. Here we select four promising exoplanetary systems for detecting this effect: HIP 65, NGTS-6, NGTS-10 and WASP-173. We present 33 new transit light curves taken with the 1.54 m Danish Telescope, and analyse these alongside photometric data from the Transiting Exoplanet Survey Satellite and transit timing data from the literature. We construct two ephemeris models for each target: a linear ephemeris and a shrinking orbital period due to tidal decay. The linear ephemeris is preferred for three of the four models - the highest significance for the quadratic ephemeris is over 3-sigma for WASP-173. We compare these results to theoretical predictions for tidal dissipation of gravity waves in radiation zones, and find that wave breaking is predicted only in WASP-173, making rapid decay plausible in this system but unclear in the other three. The sensitivity of transit timings to orbital decay depends on the square of the time interval covered by available observations, so our results establish a useful baseline against which future measurements can be compared. NGTS-6 and NGTS-10 are important objects for future study as they are in the first field to be observed by the upcoming PLATO mission.
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All authors A. W. Griffiths, J. Southworth, L. Alegre, F. Amadio, M. I. Andersen, A. J. Barker, M. Basilicata, M. Bonavita, V. Bozza, M. J. Burgdorf, R. E. Cannon, G. Columba, M. Dominik, A. Donaldson, R. Figuera Jaimes, T. C. Hinse, M. Hundertmark, U. G. Jørgensen, E. Khalouei, P. Longa-Peña, L. Mancini, F. Manni, B. Murphy, N. Peixinho, M. Rabus, S. Rahvar, H. Rendell-Bhatti, P. Rota, A. Rożek, S. Sajadian, J. Skottfelt, C. Snodgrass, J. Tregloan-Reed

Solar and Stellar Astrophysics

The Role of Binary Configuration in Shaping Nova Evolution via Wind Accretion in Symbiotic Systems

Irin Babu Vathachira, Yael Hillman and Amit Kashi

We investigate the impact of the Bondi–Hoyle–Lyttleton (BHL) accretion mechanism on the evolution of nova eruptions in symbiotic systems by systematically varying three key input parameters: the initial donor (asymptotic giant branch; AGB) mass, the initial white dwarf (WD) mass, and the initial binary separation ($a$). We explore models with AGB masses in the range $1.5$–$3.5\,{\rm M_{\odot}}$, WD masses in the range $0.7$–$1.25\,{\rm M_{\odot}}$, and separations in the range $1$–$8\,{\rm kR_{\odot}}$. We find that all models exhibit a significant long-term orbital increase. This trend is primarily driven by the fact that approximately $99\%$ of the AGB mass is lost from the system, either directly via a wind that is not accreted by the WD, or accreted onto the WD and subsequently ejected during nova eruptions. As a result, the secular orbital response to mass loss or mass transfer dominates over angular-momentum-loss sinks that could otherwise shrink the orbit, producing a consistent orbital widening. Consequently, all WD masses gradually decrease with time. More massive WDs achieve higher mass-transfer efficiencies and accretion rates, leading to slightly higher mass-retention efficiencies per nova. However, because higher accretion rates also produce more frequent eruptions, the total WD mass lost over the AGB lifetime is larger in these systems. We conclude that symbiotic systems transferring mass via the BHL mechanism are unlikely to be viable progenitors of Type Ia supernovae.
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Earth and Planetary Astrophysics · Cross-listed from physics.flu-dyn

Online learning of subgrid-scale models for quasi-geostrophic turbulence in planetary interiors

Hugo Frezat, Thomas Gastine and Alexandre Fournier

Machine learning approaches to subgrid-scale (SGS) modeling are now well established in atmospheric and oceanic applications. Among these, online end-to-end learning, where the differentiable solver participates in the training, has shown particular promise. Yet existing studies are largely restricted to idealised periodic domains, with no mechanical boundaries, precluding them from addressing the dynamics of bounded rotating flows relevant to planetary interiors. Here we consider two-dimensional quasi-geostrophic turbulence in a rapidly rotating annular bounded domain. We examine three configurations varying the geometry of the container and the rotation rate. The system exhibits key features such as zonal jets, Rossby waves, and, in the spherical shell geometry, a slow quasi-periodic inward drift of the jets. The spectral properties of the zonal and non-zonal flow can be understood in the framework of zonostrophic turbulence theory. We develop a differentiable solver for this system, which allows us to train SGS models online, over a time span of one turnover time, using coarse-grained data from direct numerical simulations. In all cases, a SGS model trained on a single turnover time accurately reproduces global integrated diagnostics, energy spectra as well as long-term dynamical behaviours, such as jet migration, occurring on timescales which exceed the training window by one order of magnitude. The online-trained model further outperforms classical hyperdiffusivity and Leith closure schemes, for which reducing the radial resolution is impractical. The resulting speed-up paves the way to further investigations of long-term geophysical fluid processes beyond the reach of direct numerical simulations.
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High Energy Astrophysical Phenomena

Point-symmetric morphology in supernova remnant G11.2-0.3: the jittering jets explosion mechanism

Noam Soker

I identify a point-symmetric morphology in the core-collapse supernova (CCSN) remnant SNR G11.2-0.3 composed of three pairs of opposite morphological features, and attribute their shaping to three energetic pairs of jets during the explosion process in the frame of the jittering jets explosion mechanism (JJEM). The pairs of morphological features are two opposite rings, a strip of dense ejecta extending on both sides of the central pulsar PSR J1811-1925, and an ear-nozzle opposite structure. According to the JJEM, additional weaker pairs of jets may also have participated in the explosion. The jets' axis from the ear to the nozzle coincides with the axis of the presently active pulsar jets, which is the pulsar spin axis. The jets of this pair were the last that the newly born neutron star launched during the explosion, and the accretion disk that launched these jets spun up the neutron star in the same direction as the jets. The identification of a point-symmetric morphology in SNR G11.2-0.3 strengthens the claim that the JJEM is the primary explosion mechanism of CCSNe.
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Instrumentation and Methods for Astrophysics

Estimating differential pistons for the Extremely Large Telescope using focal plane imaging and a residual network

P. Janin-Potiron, M. Gray, B. Neichel et al. (+6 more)

As the Extremely Large Telescope (ELT) approaches operational status, optimising its imaging performance is critical. A differential piston, arising from either the adaptive optics (AO) control loop, thermomechanical effects, or other sources, significantly degrades the image quality and is detrimental to the telescope's overall performance. In a numerical simulation set-up, we propose a method for estimating the differential piston between the petals of the ELT's M4 mirror using images from a 2x2 Shack-Hartmann wavefront sensor (SH-WFS), commonly used in the ELT's tomographic AO mode. We aim to identify the limitations of this approach by evaluating its sensitivity to various observing conditions and sources of noise. Using a deep learning model based on a ResNet architecture, we trained a neural network (NN) on simulated datasets to estimate the differential piston. We assessed the robustness of the method under various conditions, including variations in Strehl ratio, polychromaticity, and detector noise. The performance was quantified using the root mean square error (RMSE) of the estimated differential piston aberration. This method demonstrates the ability to extract differential piston information from 2x2 SH-WFS images. Temporal averaging of frames makes the differential piston signal emerge from the turbulence-induced speckle field and leads to a significant improvement in the RMSE calculation. As expected, better seeing conditions result in improved accuracy. Polychromaticity only degrades the performance by less than 5% compared to the monochromatic case. In a realistic scenario, detector noise is not a limiting factor, as the primary limitation rather arises from the need for sufficient speckle averaging. The network was also shown to be applicable to input images other than the 2x2 SH-WFS data.
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All authors P. Janin-Potiron, M. Gray, B. Neichel, M. Dumont, J.-F. Sauvage, C. T. Heritier, P. Jouve, R. Fetick, T. Fusco

Astrophysics of Galaxies

The Eddington Ratio Distribution of Narrow Line Active Galactic Nuclei

Michael R. Blanton, Arjun Suresh, Kyle B. Westfall et al. (+2 more)

We measure the Eddington ratio distribution of local optical narrow-line active galactic nuclei (AGN) as a function of host galaxy properties, as a potential test of galaxy formation theories of AGN feedback. We extract central emission-line fluxes using data from the Mapping Nearby Galaxies at APO (MaNGA) sample of the Sloan Digital Sky Survey IV Data Release 17. Using the line ratio diagnostic techniques of Ji & Yan (2020), we identify AGN galaxies and determine their H$\beta$ and [OIII] line luminosities. For all galaxies not identified as AGN, we determine the threshold line luminosity they would have needed to be identified as AGN. These luminosity thresholds allow us to account for selection effects that otherwise would lead to strongly biased results. From the H$\beta$ luminosities and luminosity detection thresholds, accounting for selection effects, we measure the luminosity and Eddington ratio distributions of Seyferts as a function of specific star formation rate (sSFR) and stellar mass. Defining $F_{\rm AGN}$ as the occurrence rate of AGN above a fixed Eddington ratio of $10^{-3}$, we find that $F_{\rm AGN}$ is constant or increasing with stellar mass for star forming galaxies and declines strongly with stellar mass for quiescent galaxies. At stellar masses $\log_{10} M_\ast > 10.25$, the occurrence rate increases monotonically with sSFR. At low statistical significance, in our lowest mass bins $9.25 < \log_{10} M_\ast < 10.25$, $F_{\rm AGN}$ peaks at intermediate sSFR. These patterns reveal a complicated dependence of AGN activity on galaxy properties for theoretical models to explain.
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All authors Michael R. Blanton, Arjun Suresh, Kyle B. Westfall, Dou Liu, John Moustakas

Cosmology and Nongalactic Astrophysics

Forecasting synchrotron spectral parameters with QUIJOTE-MFI2 in combination with Planck and WMAP

Ana Almeida, José Alberto Rubiño-Martín, Roke Cepeda-Arroita et al. (+2 more)

We present a parametric component separation forecast for the QUIJOTE-MFI2 instrument (10-20 GHz), assessing its impact on constraining polarised synchrotron emission at $1^\circ$ FWHM and $N_{\rm side}=64$. Using simulated sky maps based on power-law and curved synchrotron spectra, we show that adding QUIJOTE-MFI2 to existing WMAP+$Planck$+MFI data yields statistically unbiased parameter estimates with substantial uncertainty reductions: improvement factors reach $\sim$10 for the synchrotron spectral index ($\beta_s$), $\sim$5 for the curvature parameter ($C_s$), and $\sim$43 for polarisation amplitudes in bright regions. Deep QUIJOTE cosmological fields enable $\beta_s$ constraints even in intrinsically low SNR regions where WMAP+$Planck$ alone remain prior-dominated. Current combined sensitivities are insufficient to detect a synchrotron curvature of $C_s=-0.052$ on a pixel-by-pixel basis, but a $2\sigma$ detection is achievable for $|C_s|\gtrsim 0.14$ in the brightest regions of the Galactic plane. In those deep cosmological fields, combining QUIJOTE-MFI2 with WMAP and $Planck$ reduces the median synchrotron residual at 100 GHz by a factor of 6, to 0.033 $\mu$K$_{\rm CMB}$. These results demonstrate that QUIJOTE-MFI2 will provide critical low-frequency information for modelling Galactic synchrotron emission, offering valuable complementary constraints for future CMB surveys such as LiteBIRD and the Simons Observatory.
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All authors Ana Almeida, José Alberto Rubiño-Martín, Roke Cepeda-Arroita, Ricardo Tanausú Génova-Santos, Debabrata Adak

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

Impact of conversion-driven processes on singlet-doublet Majorana dark matter relic

Partha Kumar Paul, Sujit Kumar Sahoo and Narendra Sahu

The singlet-doublet dark matter model offers a rich framework for exploring the nature of dark matter (DM) through its unique fermion structure. In this model, the important parameters are the singlet-doublet mass splitting $\Delta{M}$, the singlet-doublet mixing angle $\sin\theta$, and the DM mass $M_{\rm DM}$. If the DM is assumed to be of Dirac nature, then the annihilation, co-annihilation, and conversion driven processes combined allow a range of parameter space: $100~{\rm GeV} \lesssim M_{\rm DM}\lesssim750$ GeV and $10^{-6}\lesssim\sin\theta\lesssim0.04$ for $\Delta{M}>1$ GeV. While the nature of DM, either Dirac or Majorana, is not known, in this work, we assume the singlet-doublet DM to be of Majorana type and find that the relic density and direct detection can be satisfied over a larger parameter space. In particular, the allowed ranges of DM mass and $\sin\theta$ are $100~{\rm GeV}\lesssim M_{\rm DM}\lesssim1750$ GeV and $2\times10^{-7}\lesssim\sin\theta\lesssim0.45$ for $\Delta{M}>1$ GeV.
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Astrophysics of Galaxies

Feedback and Star Formation Efficiency in High-Mass Star-Forming Regions

Birka Zimmermann, Stefanie Walch, Seamus D. Clarke et al. (+2 more)

To advance our understanding of massive star formation, it is essential to perform a comprehensive suite of simulations that explore the relevant parameter space and include enough physics to enable a comparison with observational data. We simulate the gravitational collapse of isolated, parsec-scale turbulent cores using the FLASH code, modelling stars as sink particles. Our simulations incorporate ionizing radiation and the associated radiation pressure from stellar sources, and non-ionizing radiation and its dust heating, along with self-consistent chemistry, to capture the properties of emerging ultra-compact HII regions. Dust, gas, and radiation temperature are computed independently. The initial conditions are informed by ALMAGAL observations. We assess stellar feedback, comparing ionizing radiation and radiation pressure. Ionizing radiation ultimately halts mass accretion on to sink particles, while direct radiation pressure enhances the expansion of HII regions. Heating from non-ionizing radiation suppresses fragmentation. We examine the effect of spatial resolution, finding that higher resolution leads to more sink particles which are situated in environments with higher densities. As a result, ionizing radiation remains trapped longer, allowing continued accretion and yielding a higher overall star formation efficiency (SFE). We explore the impact of varying initial conditions, including the core density profile, virial parameter, and metallicity. Our parameter study reveals that a flatter density profile, higher virial parameter, and increased metallicity promote fragmentation, potentially enhancing the SFE by slowing the growth of the most massive stars and delaying the onset of stellar feedback. Overall, we find SFEs between 35% and 57%. Stellar feedback dictates the final SFE.
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All authors Birka Zimmermann, Stefanie Walch, Seamus D. Clarke, Richard Wünsch, Andre Klepitko

High Energy Astrophysical Phenomena

A comparison of time-dependent Cloudy astrophysical code simulations with experimental X-ray spectra from keV laser-generated argon plasmas

N. Rathee, F.P. Keenan, R.J.R. Williams et al. (+4 more)

We have generated strongly photoionized Ar plasmas in experiments designed to use primarily X-ray L-shell line emission generated from Ag foils irradiated by the VULCAN high-power laser at the UK Central Laser Facility. The principle of the experiment is that use of line emission rather than the usual sub-keV quasi-blackbody source allows keV radiation to play a more dominant role compared to softer X-rays and thus mimic the effect of a blackbody with a higher effective spectral temperature. Our aim is to reproduce in the laboratory the extreme photoionization conditions found in accretion-powered astrophysical sources. In this paper, we compare the experimental results on K-$\beta$ X-ray Ar spectra with modelling using the time-dependent version of the Cloudy astrophysical code. The results indicate that photoionized laboratory plasmas can be successfully modelled with codes such as Cloudy that have been developed for application to astrophysical sources. Our comparison of simulation and experiment shows that the flux of sub-keV photons that photoionize the outer-shell electrons can have a significant effect, and that detailed measurements of the X-ray drive spectrum across all photon energy ranges are crucial for accurate modelling of experiments.
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All authors N. Rathee, F.P. Keenan, R.J.R. Williams, G.J. Ferland, S.J. Rose, S. White, D. Riley

Cosmology and Nongalactic Astrophysics

Early Universe Constraints on Variations in Fundamental Constants Induced by Ultralight Scalar Dark Matter

Subhajit Ghosh, Kimberly K. Boddy and Tien-Tien Yu

We study the cosmological impact of ultralight dark matter (ULDM) with a quadratic coupling to Standard Model particles. In addition to the suppression of small-scale power from ULDM itself, the coupling induces a variation of fundamental constants that is modulated by the ULDM oscillatory field value. In this work, we consider the ULDM-induced, time-dependent variation of the fine structure constant and the mass of the electron. These variations modify the predicted abundance of light elements during Big Bang nucleosynthesis (BBN) and the process of recombination, thereby affecting the anisotropies of the cosmic microwave background (CMB). We use CMB anisotropy data and baryon acoustic oscillation measurements to obtain constraints on the variation of couplings over a wide range of ULDM masses. We self-consistently account for the modification of the primordial helium abundance during BBN in computing the CMB power spectra. We find that the allowed ULDM fraction of total dark matter abundance is more constrained for ULDM masses $\lesssim 10^{-26}~\mathrm{eV}$ in the presence of the variations. Moreover, our constraints on the variational couplings for ULDM masses $\lesssim 10^{-27}~\mathrm{eV}$ are stronger than the ones derived from the primordial helium abundance at BBN. Under our ULDM model, the variation of fundamental constants has no appreciable impact on the Hubble constant inferred from CMB data and thus does not present a viable solution to the Hubble tension.
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Astrophysics of Galaxies

VENUS: A Strongly Lensed Clumpy Galaxy at $z\sim11-12$ behind the Galaxy Cluster MACS J0257.1-2325

Minami Nakane, Vasily Kokorev, Seiji Fujimoto et al. (+75 more)

We present the discovery of a strongly lensed galaxy at $z\sim11-12$, dubbed the “Misty Moons”, identified in the JWST Treasury Survey, Vast Exploration for Nascent, Unexplored Sources (VENUS). The Misty Moons is gravitationally lensed by the galaxy cluster MACS J0257.1-2325 at $z=0.505$, and has five multiple images suggested by two independent lensing models. Two of the five images, ID1 and ID2 ($\mu\sim 20-30$), are very bright (F200W$\sim26$ AB mag) and exhibit blue SEDs with prominent Ly$\alpha$ breaks. In the source plane, the Misty Moons is a sub-$L^*$ galaxy ($M_{\rm UV}\sim-18.0$ mag) resolved into multiple stellar clumps, each of which has an effective radius of $r_\mathrm{eff}\sim 10-70$ pc and a stellar mass of $\sim10^7\ M_\odot$. These clumps dominate the stellar mass budget of the Misty Moons ($\gtrsim80\%$), similar to other high-$z$ clumps, which suggests a highly clustered mode of star formation in the early Universe, unlike seen in local dwarf galaxies. We convolve the source-plane image with the JWST/NIRCam point-spread function to produce a mock NIRCam image of the Misty Moons without lensing magnification, and find that the intrinsic galaxy has a radial surface-brightness profile comparable to those of $z\gtrsim10$ faint galaxies, such as JADES-GS-z13-0 and JADES-GS-z14-1, indicating that the Misty Moons represents a typical $z\gtrsim10$ faint galaxy. The Misty Moons, a lensed galaxy with resolved internal structures, provides an ideal laboratory for exploring the early stages of galaxy formation at $z\gtrsim10$.
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All authors Minami Nakane, Vasily Kokorev, Seiji Fujimoto, Masami Ouchi, Derek J. McLeod, Miriam Golubchik, Masamune Oguri, Adi Zitrin, Cecilia Bondestam, Callum T. Donnan, Gabriel Brammer, Steven L. Finkelstein, Chris Willott, Gregor Rihtarsic, Guillaume Desprez, Angela Adamo, Eros Vanzella, Maruša Bradač, Matteo Messa, Hiroto Yanagisawa, Fengwu Sun, Henry C. Ferguson, Ray A. Lucas, Dan Coe, Johan Richard, Abdurro'uf, Hollis B. Akins, Joseph F. V. Allingham, Ricardo O. Amorín, Yoshihisa Asada, Hakim Atek, Rachel Bezanson, Larry D. Bradley, John Chisholm, Christopher J. Conselice, Pratika Dayal, Miroslava Dessauges-Zavadsky, Jose M. Diego, Andreas L. Faisst, Gavin Farley, Qinyue Fei, Brenda L. Frye, Yoshinobu Fudamoto, Lukas J. Furtak, Yuichi Harikane, Tiger Yu-Yang Hsiao, Yolanda Jiménez-Teja, Jeyhan S. Kartaltepe, Tomokazu Kiyota, Anton M. Koekemoer, Claudia del P. Lagos, Georgios E. Magdis, Ashish Kumar Meena, Lamiya Mowla, Gaël Noirot, Pascal A. Oesch, Yoshiaki Ono, Rafael Ortiz III, Richard Pan, Casey Papovich, Justin D. Pierel, Massimo Ricotti, Luke Robbins, Daniel Schaerer, Raffaella Schneider, Tommaso Treu, Francesco Valentino, Rogier A. Windhorst, Franz E. Bauer, Volker Bromm, Eiichi Egami, Mauro González-Otero, Kotaro Kohno, Ivo Labbe, Jorryt Matthee, Marcie Mun, Rohan P. Naidu, Roberta Tripodi

Solar and Stellar Astrophysics

PyEMILI: A New Generation Computer-aided Spectral Line Identifier – II. Emission-line Identification and Plasma Diagnostics of a Sample of Gaseous Nebulae

Zhijun Tu, Xuan Fang, Jorge García-Rojas et al. (+2 more)

In order to test the robustness and reliability of the new generation spectral-line identifier PyEMILI, as initially introduced in Paper I, in line identification and establish a reference/benchmark dataset for future spectroscopic studies, we run the code on the line lists of a selected sample of emission-line nebulae, including planetary nebulae (PNe), HII regions, and Herbig-Haro (HH) objects with deep high-dispersion spectroscopic observations published over the past two decades. The automated line identifications by PyEMILI demonstrate significant improvements in both completeness and accuracy compared to the previous manual identifications in the literature. Since our last report of PyEMILI, the atomic transition database used by the code has been further expanded by cross-matching the Kurucz Line Lists. Moreover, to aid the PyEMILI identification of numerous faint optical recombination lines (ORLs) of CII, NII, OII and NeII, we compiled a new dataset of effective recombination coefficients for these nebular lines, and created a new subroutine in the code to generate theoretical spectra of heavy-element ORLs at various electron temperature and density cases; these theoretical spectra can be used to fit the observed recombination spectrum of a PN to obtain the electron temperature, density and ionic abundances using the Markov-Chain Monte Carlo (MCMC) method. We present MCMC-derived parameters for a sample of PNe. This work establishes PyEMILI as a robust and versatile tool for both line identification and plasma diagnostics in deep spectroscopy of gaseous nebulae.
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All authors Zhijun Tu, Xuan Fang, Jorge García-Rojas, Robert Williams, Jifeng Liu