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Physics Astrophysics

astro-ph Watch Astrophysics

Sunday 2 August

Instrumentation and Methods for Astrophysics

Towards optimal photometric calibration of digital astronomical plates with deep learning

Mingyang Ma, Haibo Yuan, Lin Yang et al. (+8 more)

Photometric calibration of digitized photographic plates is commonly modeled with separable magnitude-, color-, and position-dependent terms, but this separability can break down when image quality varies across the field in a magnitude-dependent way, leaving coupled spatial systematics in the residuals. We introduce a deep-learning calibration framework, the Multi-Feature Fused Network (MFF-Net), which takes instrumental magnitude, color, and pixel coordinates as input and learns a single nonlinear correction that jointly captures their coupled dependencies. Tests on 1{,}200 digitized Chinese plates show that MFF-Net consistently outperforms the MYX25 method (Ma et al. 2025), improving the 5th–95th percentile precision from 0.11–0.26~mag to 0.08–0.18~mag and delivering an approximately factor-of-two gain for bright sources. The learned correction largely removes the magnitude–position coupling seen in post-calibration residual maps, enabling higher-precision plate photometry and more reliable use of large historical plate archives.
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All authors Mingyang Ma, Haibo Yuan, Lin Yang, Kai Xiao, Bowen Huang, Shiyin Shen, Zhengjun Shang, Yong Yu, Meiting Yang, Zhenghong Tang, Jianhai Zhao

Astrophysics of Galaxies · Cross-listed from physics.plasm-ph

Sub-sonic compressible magnetohydrodynamic turbulence I. Alfvénic and fast-magnetosonic injection, amplitude dependence, and compressibility effects

Eleonora Puzzoni, Silvio Sergio Cerri, Dimitri Laveder et al. (+2 more)

We investigate how sub-sonic compressible magnetohydrodynamic (MHD) turbulence properties that are relevant for cosmic-ray (CR) transport in the Galaxy are affected by the nature and amplitude of initial fluctuations, and by the plasma compressibility $\beta$. We perform 3D simulations of decaying compressible ideal-MHD turbulence at $1024^3$ resolution with the PLUTO code. The level of density fluctuations in fully developed turbulence is insensitive to whether this state is reached starting from Alfvénic or fast-magnetosonic perturbations. Fast-magnetosonic injection is characterized by an early phase of rapid shock dissipation, followed by a turbulence-dominated decay with a rate comparable to that of the Alfvénic case. The contribution of fast-magnetosonic fluctuations in fully developed turbulence remains relevant only when the initial injection consists exclusively of fast modes. Large-amplitude turbulence ($\delta B/B_0>1$) is characterized by a nearly isotropic Kolmogorov or Iroshnikov-Kraichnan spectrum for Alfvénic or fast-magnetosonic injection, respectively. At low amplitudes ($\delta B/B_0\ll1$), both initial Alfvénic and mixed-wave perturbations lead to strongly anisotropic turbulence with spectra $\propto k_\perp^{-5/3}$ and $\propto k_z^{-2}$ (becoming steeper at $\beta\gg1$), whereas fast-magnetosonic perturbations produce a turbulent state populated by shocks with a nearly isotropic $k^{-2}$ spectrum. Magnetic-field curvature and mirror structures are strongly sensitive to fluctuation amplitude and plasma $\beta$. The predicted -2.5 power-law scaling emerges only in the large-amplitude regime at high $\beta$. This work highlights that features of sub-sonic compressible MHD turbulence that may affect CR transport are sensitive to large-scale conditions and to the plasma $\beta$. Their effect on CR diffusion and field-line random walk is the object of Paper II.
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All authors Eleonora Puzzoni, Silvio Sergio Cerri, Dimitri Laveder, Thierry Passot, Pierre-Louis Sulem

High Energy Astrophysical Phenomena

Propagation Diagnostics of Supernova Remnant Environments around Young Repeating Fast Radio Bursts. I. Hydrodynamic Evolution of the Source-local Dispersion Measure

Xiang-Er Fang, Zhen-Yin Zhao, Yi-Qing Lin et al. (+2 more)

Repeating fast radio bursts may reside in young supernova remnant (SNR) environments whose evolving plasma contributes to the observed dispersion measure (DM). We use two-dimensional axisymmetric hydrodynamic simulations to study the interaction between a continuous anisotropic wind from a young neutron star and homologously expanding supernova ejecta. We follow the evolution to approximately 160 yr and calculate the source-local DM along different viewing directions, using a passive tracer to separate wind and nonwind contributions. In the fiducial model, the strongly polar-focused wind inflates a low-density cavity, while the swept-up shell remains broadly rounded and the DM shows moderate angular variation. The DM is dominated by ejecta and swept-up nonwind material. The solid-angle-averaged ambient-subtracted excess DM declines throughout the evolution, approximately following $t_{\rm age}^{-2}$ during the first several tens of years and becoming modestly steeper later. Variations in wind and ejecta parameters modify the normalization, early evolution, and viewing-angle dependence, but the angle-averaged DM declines in all models, while different bipolar wind profiles produce similar long-term evolution. For FRB 20190520B, the fiducial model reaches a decline rate comparable to the source-frame value inferred from observations at approximately 20 yr, when the mean excess DM is approximately $1.8\times10^2~{\rm pc,cm^{-3}}$. Thus, such a young environment can retain a substantial electron column while producing a rapid secular decrease. Repeater diversity suggests that SNR-driven expansion may coexist with additional time-dependent plasma structures or ionization changes.
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All authors Xiang-Er Fang, Zhen-Yin Zhao, Yi-Qing Lin, Hao-Tian Lan, Fa-Yin Wang

Astrophysics of Galaxies

The physical mechanism for two rapid changing-look AGNs: SDSS J0225+0030 and SDSS J1723+5504

Shuang-Liang Li, Xinwu Cao and Wei-Min Gu

SDSS J0225+0030 and SDSS J1723+5504 are two turn-on changing-look active galactic nuclei (CL AGNs) with transition timescales shorter than one year. Such short timescales pose a challenge for the current physical models of CL AGNs. We investigate this issue by exploring two possible mechanisms in this work. First, we consider the effect of a large-scale magnetic field on the viscous timescale, which can increase the radial velocity of the accretion disk. However, it is found that the timescale given by this model remains significantly longer than one year. Second, we improve the model of \citet{2025ApJ...988..207L}, which proposed that the inner thin disk in the bright state may form through the collapse of an advection-dominated accretion flow (ADAF) in the dim state, rather than being replaced by the advection of the outer thin disk. We re-estimate the transition radius $R_{\rm tr}$ between the inner ADAF and the outer thin disk through the observed variation of optical flux between the bright state and dim state. It is found that $R_{\rm tr}$ can be significantly reduced in these two objects owing to the lower gas temperature in the inner disk region (of the order of $10^4$ K), resulting from their large black hole masses ($\sim 10^9 M_{\odot}$) and small Eddington-scaled mass accretion rates ($\sim 0.01$). The cooling timescales given by the revised model in these two objects are found to be comparable to the observed transition timescales.
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High Energy Astrophysical Phenomena

Deciphering the "Green Monster" in Cassiopeia A: Puncturing and sculpting a heterogeneous circumstellar shell

S. Orlando, H.-T. Janka, D. Milisavljevic et al. (+6 more)

JWST observations of Cassiopeia A have revealed the "Green Monster" (GM), a pockmarked region of shocked circumstellar medium (CSM) characterized by circular holes surrounded by bright rings. The origin of these structures remains debated, with proposed mechanisms including post-shock sculpting by ejecta fingers and pre-shock puncturing by fast-moving knots (FMKs). We investigate the physical viability of the FMK-driven scenario using three-dimensional hydrodynamic simulations of FMKs interacting with a dense circumstellar shell, followed by the passage of the supernova remnant forward shock. By exploring a range of knot properties and shell densities, we compare the resulting hole-ring systems with JWST observations. Primary FMKs reproduce the qualitative morphology of the GM but generally produce hole-ring systems larger than the observed $1^{\prime\prime}-3^{\prime\prime}$ ($\sim0.016-0.048$ pc) structures unless the knots are relatively slow ($\lesssim8000$ km s$^{-1}$) and the shell is dense ($n_{\rm sh}\gtrsim200$ cm$^{-3}$). Moreover, the resulting structures are short-lived, becoming significantly distorted within $30-60$ yr after the forward-shock passage. The GM's diverse hole-ring systems and complex kinematics cannot be attributed to a single idealized scenario, but can be instead explained by the simultaneous action of three mechanisms operating within a structured, heterogeneous CSM. While large cavity relics are carved by early-stage primary FMKs, compact pristine rings are produced by recent "first contact" punctures of secondary knots from fragmented ejecta fingers, and older structures are continuously sculpted by long-term post-shock interactions with large-scale ejecta fingers.
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All authors S. Orlando, H.-T. Janka, D. Milisavljevic, I. De Looze, T. Temim, R. Fesen, B.-C. Koo, M. Miceli, F. Bocchino

High Energy Astrophysical Phenomena

The PSR J0435+3233 Triple System

Z. L. Yang, J. L. Han, Y. Yan et al. (+9 more)

The detailed evolution of triple star systems is complicated and poorly known. Using archived optical/infrared and $\gamma$-ray data, we identified the pulsar PSR~J0435+3233 as a $\gamma$-ray pulsar in a hierarchical triple system, with a helium white dwarf (WD) as a close inner binary companion and a Sun-like star as the distant tertiary. PSR~J0435+3233 and the WD companion are in a circular orbit with a period of $P_{\rm orb1} = 8.0$~days and an eccentricity of $e=0.00016$. The tertiary is a G-type subgiant with a mass of $0.98(12) M_\odot$ at a distance of $2.1(4)$ kpc from the Earth. By simultaneously fitting the observed spin-period variations of the $\gamma$-ray emission (over 16.7 years) and radio emission (over 4.9 years) from PSR~J0435+3233, the changes in the inner orbital parameters, the Shapiro delay, Gaia astrometry, and the outer companion mass, we determined the outer elliptical orbit for the tertiary, with a period $P_{\rm orb2} = 73.5$~yrs and an eccentricity $e_2 = 0.598$. The outer orbit is either nearly perpendicular to the inner orbit with a mutual inclination of $\sim 85^\circ$, or moderately inclined by $\sim 54^\circ$. For the former geometry, the pulsar, the WD, and the tertiary star have masses of $1.16(5) M_\odot$, $0.273(8) M_\odot$, and $0.91(5) M_\odot$, respectively; for the latter geometry, the corresponding masses are $1.34(15) M_\odot$, $0.305(23) M_\odot$, and $1.13(7) M_\odot$. This is a unique triple system for detailed multi-band observations and for studying the evolutionary path and dynamic processes of a primordial triple star system. It will ultimately evolve into a system consisting of a neutron star and two white dwarfs.
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All authors Z. L. Yang, J. L. Han, Y. Yan, Bin Liu, Y. L. Guo, M. K. Yang, Bo Wang, W. M. Gu, J. Li, L. H. Li, J. Xu, J. N. Fu

Cosmology and Nongalactic Astrophysics

Do we really need alternatives to the $\omega_0\omega_a$CDM parameterization after the DESI DR2?

Youri Carloni, Orlando Luongo and Marek Biesiada

We introduce a density-level pivot construction for the Chevallier-Polarski-Linder (CPL) parameterization by defining the normalized dark energy density $f_p\equiv f_{\rm DE}(a_p)$ and the equation of state $\omega_p\equiv \omega(a_p)$ at an optimized pivot scale factor $a_p$. This reparameterization leaves the underlying CPL cosmology unchanged and allows the two models to be compared using parameters with a direct physical interpretation at the epoch where the data are most sensitive. Accordingly, following the DESI DR2 results, we compare a newly proposed $f_a f_b$CDM parameterization, based on a second-order Taylor expansion of the normalized dark energy density, with the standard $w_0w_a$CDM model. In particular, we constrain the original and pivoted parameterizations using compressed cosmic microwave background (CMB), DESI DR2 baryon acoustic oscillations (BAO), cosmic chronometers (CC), and Pantheon+ Type Ia supernovae data, with the SH0ES prior imposed on $H_0$. We find that applying the same density-level pivot prescription to the $w_0w_a$CDM model substantially reduces the correlation between its dark energy parameters and provides tighter and more stable constraints. The statistical comparison shows that this model remains favored over the Taylor expansion of the dark energy density, even when both models are analyzed in the optimized parameter basis. Moreover, the pivoted CPL parameterization accurately reproduces the background evolution of quintessence models, providing a reliable phenomenological approximation to the underlying dark energy dynamics, better than the $f_af_b$CDM model. We conclude that changing the parameter basis improves the performance of the $w_0w_a$CDM model, which emerges as the most suitable framework to describe the dark energy sector within the class of models considered here.
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High Energy Astrophysical Phenomena

Simulations of Electromagnetic Cascades in the Intergalactic Medium with Plasma Instabilities: the grplinst Code

Rafael Alves Batista and Andrey Saveliev

Electromagnetic cascades initiated by TeV gamma rays from distant blazars provide one of the cleanest indirect probes of the intergalactic medium and, in particular, of intergalactic magnetic fields. However, their interpretation is not completely clear because of an open theoretical question: the extent to which the electron-positron beams generated in the cascade can lose energy through collective plasma processes. If this occurs before inverse Compton scattering produces secondary gamma rays, then the cascade is quenched. Here we present grplinst, a plugin for the CRPropa framework that models plasma-instability cooling acting on electrons and positrons during propagation. We describe the implementation of several prescriptions proposed in the literature, and present illustrative examples. The code is suitable both for bracketing theoretical uncertainties and for performing systematic studies of how plasma-instability assumptions propagate into gamma-ray observables and inferred intergalactic magnetic-field constraints, which is essential for interpreting current and forthcoming observations by high-energy gamma-ray observatories.
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Cosmology and Nongalactic Astrophysics

AGN Reverberation Mapping with LITMUS: Fundamental Limits on lag Recovery Rates

Hugh McDougall, Tamara M. Davis, Benjamin J. S. Pope et al. (+4 more)

Reverberation mapping of active galactic nuclei provides one of the most direct probes of the geometry and kinematics of the broad-line region by measuring time delays between continuum and line variability. Modern RM surveys frequently suffer difficulties with lag measurements due to poor signal to noise and aliasing, whereby multimodal lag posterior distributions arise due to seasonal gaps in our data. These challenge the reliability of commonly used fitting tools such as JAVELIN, which can return a high rate of false positives. We implement a new lag measurement package, LITMUS, and introduce a new framework that uses Bayesian evidence to identify false positive lag measurements, as well as examine the question of how many AGN present detectable lags in high redshift industrial scale surveys like OzDES and SDSS. Our analysis differs from previous RM studies in six key respects: (i) our inference is robust to the previously under-diagnosed numerical component of aliasing, (ii) we use a consistent methodology for all sources, (iii) uncertainty in the underlying AGN variability is fully marginalised, (iv) lag significance is assessed via Bayesian model comparison rather than heuristic metrics, (v) false-positive rates are quantified by comparison against random-chance recoveries and (vi) we use marginal likelihoods to distinguish between sources where a lag is not detectable in our data and sources that show no evidence of reverberation. Applied to the OzDES sample, we find that previous RM studies are likely to have overestimated the confidence of recovered lags, and we find a stark contrast between a low reverberation percentage for the MgII line (3-28% depending on assumptions) and much higher percentages in the CIV and especially the H$\beta$ line, which is consistent with 100%. We also present a re-analysed set of lags from the OzDES sample with better quantified reliabilities
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All authors Hugh McDougall, Tamara M. Davis, Benjamin J. S. Pope, Paul Martini, Zhefu Yu, Chris Lidman, Geraint F. Lewis

Earth and Planetary Astrophysics

CHEOPS photometry from 2024 reveals a reversal in the transit-timing variations of AU Mic c

Z. Garai, Gy. M. Szabó, D. Gandolfi et al. (+90 more)

We present new CHEOPS transit observations of AU Mic b and AU Mic c obtained between June and September 2024, extending the baseline of transit-timing measurements of this young planetary system. For AU Mic b, the timing signal is well established, with a semi-amplitude (10 $\pm$ 3 min) and a characteristic modulation timescale (1168 $\pm$ 20 d) consistent with previous determinations. By contrast, the new CHEOPS data show that the large transit-timing deviation of AU Mic c reported previously was not sustained. After the steadily increasing timing trend observed in 2022 and 2023, the 2024 timings returned closer to the zero point of the observed-minus-calculated diagram, indicating a reversal of the previously reported behavior. For AU Mic c, both the transit-timing semi-amplitude (46 $\pm$ 26 min) and the characteristic modulation timescale (2150 $\pm$ 110 d) remain tentative. These results highlight the importance of continued long-term monitoring of the AU Mic system.
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All authors Z. Garai, Gy. M. Szabó, D. Gandolfi, A. Brandeker, A. Bonfanti, N. Billot, W. Benz, A. Heitzmann, G. Olofsson, L. Kriskovics, Á. Boldog, L. Borsato, A. Bekkelien, G. Bruno, H. P. Osborn, S. Ulmer-Moll, T. G. Wilson, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado, S. C. C. Barros, W. Baumjohann, C. Broeg, A. Castro-González, A. Collier Cameron, A. C. M. Correia, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, O. D. S. Demangeon, B.-O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, K. Gazeas, M. Gillon, M. Güdel, M. N. Günther, Ch. Helling, K. G. Isaak, T. Keller, L. L. Kiss, D. Kitzmann, J. Korth, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, A. Leleu, M. Lendl, D. Magrin, P. F. L. Maxted, B. Merín, C. Mordasini, V. Nascimbeni, D. Orikhovskyi, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Piazza, G. Piotto, D. Pollacco, T. Pribulla, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, M. Rieder, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, R. Southworth, M. Stalport, M. Steinberger, S. Sulis, S. Udry, B. Ulmer, V. Van Grootel, J. Venturini, E. Villaver, V. Viotto, N. A. Walton

Earth and Planetary Astrophysics

Orbital Periods and Equilibrium Temperatures from Single TESS Transits with a Physics-Informed Neural Network

Muhammad Hassan Javed

Planets with orbital periods longer than a TESS sector produce a single transit, and no periodogram method can measure their period: with one transit, every trial period longer than the observing baseline fits the data identically. We show this is not a sensitivity limit but a structural one – across 16 confirmed single-transit planets, Box Least Squares returns a power spectrum that is numerically constant over 95% of its search grid, and widening that grid from 27 to 200 days changes the median error by -0.0 percentage points. Orbital period can instead be recovered from transit duration through Kepler's third law and transit geometry, requiring no search grid. A direct inversion of these equations underestimates the period in 14 of 15 targets with a median signed error of -69%, because assuming a central transit returns the shortest period consistent with an observed duration. A neural network trained to marginalise over the unobserved geometry removes this bias, reaching a median absolute error of 40.5% against Box Least Squares' 79.5%, with the true period inside the 1-sigma interval for 14 of 16 targets. For NGTS-38 b, whose 180.5 d period lies ten times beyond the longest contiguous span of its TESS sector, marginalising over the unobserved geometry recovers a posterior median of 190.7 d with the true period at the 47.8th percentile, against 18.5 d from Box Least Squares. Because equilibrium temperature scales as P^(-1/3), the resulting factor-8.8 period interval compresses to a factor-2.1 temperature interval: T_eq = 445 K with a 68% interval of 272-562 K, sufficient to place the planet relative to the habitable zone from a single observation.
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Astrophysics of Galaxies

Identification and Study of Irregular Radio Sources with SKA Continuum Surveys

Tapan K. Sasmal, Xuelei Chen, Baoqiang Lao et al. (+5 more)

Radio galaxies show a wide range of morphologies, from regular double-lobed systems to more complex and distorted radio structures. In this chapter, we focus on irregular radio morphologies, defined as sources in which the radio jets and lobes deviate from a straight and symmetric structure. Bent-tail radio galaxies and winged radio galaxies are two important examples of such sources. Bent-tail radio galaxies show curved jets or lobes, mainly shaped by the interaction between radio plasma and the dense intracluster or intragroup medium. Winged radio galaxies show faint off-axis emission, which may be related to plasma backflow, jet reorientation, episodic activity, galaxy mergers, or environmental asymmetry. The Square Kilometre Array (SKA) continuum surveys will provide the sensitivity, angular resolution, frequency coverage, and image quality required to identify and study large samples of such irregular radio galaxies. These data will make it possible to detect faint extended structures, including diffuse tails, weak bridges, remnant lobes, and low-surface-brightness wings. The identification and classification of these sources will require a combination of machine-learning methods, quantitative morphology measurements, multi-wavelength host-galaxy association, and expert visual inspection. The study of irregular radio galaxies with SKA data will help to connect radio morphology with host-galaxy properties, Active Galactic Nucleus (AGN) activity, jet power, and surrounding environment. Such studies will provide important insight into jet-environment interactions, AGN feedback, the dynamical state of galaxy groups and clusters, and the evolution of radio galaxies across cosmic time.
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All authors Tapan K. Sasmal, Xuelei Chen, Baoqiang Lao, Soumen Kumar Bera, Yougang Wang, Soumen Mondal, Taotao Fang, Renyue Cen

Astrophysics of Galaxies

Investigations of MWISP Bubbles: Identification and Analysis of Enclosed Molecular Bubbles by Weight Fields

Yu Jiang, Xuepeng Chen, Ji Yang et al. (+7 more)

Molecular bubbles are widely used as tracers of stellar feedback; yet, their identification in spectral-line surveys remains challenging because both cavity morphology and kinematic structure must be assessed consistently in position–position–velocity (PPV) space. We present the Bubble-Weight Fields (BWFields) framework, a PPV-based method that for the first time enables the automated and objective identification and analysis of enclosed molecular bubbles directly from spectral-line data cubes. BWFields constructs a bubble-weight field, $W_{l,b,v}$, which encodes cumulative evidence for cavity interiors by aggregating topological signatures across multiple signal-to-noise tiers and velocity-integration scales. Contiguous cavity interiors are segmented as weight-clumps and associated with surrounding molecular gas, linking candidate bubbles to the structure of their host clouds. Shell morphology is characterized using radial intensity profiles and emission-defined intensity skeletons, which capture the shell geometry as traced by the observed emission. Bubble kinematics are quantified using azimuthally sampled position-velocity (PV) diagnostics, along with a turbulence-normalized expansion significance, which serves as a direct measure of the expansion-like velocity organisation. Applied to MWISP $^{13}$CO observations of the G17 region, BWFields identifies a population of bubble candidates with a broad range of morphologies and velocity structures in complex environments. BWFields establishes a scalable and physically interpretable framework for molecular-bubble studies in large surveys, enabling systematic investigations of stellar feedback in the Galactic interstellar medium.
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All authors Yu Jiang, Xuepeng Chen, Ji Yang, Ke Wang, Zhibo Jiang, Sheng Zheng, Yan Sun, Yang Su, Min Fang, Qing-Zeng Yan

High Energy Astrophysical Phenomena

Day-timescale Quasi-periodic Oscillations of the Gev BL Lac RX J0805.4+7534 with TESS

Xin-Shun Jin, Ting-Feng Yi, Yangwei Zhang et al. (+4 more)

This paper reports for the first time the detection of quasi-periodic oscillations (QPOs) in the light curves of the BL Lacertae object RX J0805.4+7534. The Transiting Exoplanetary Survey Satellite (TESS) observed this source in seven sectors of the sky, and we extracted the light curves for these sectors using a custom method. The presence of QPO signals was found in these light curves. To detecte the periodicity and assess the statistical significance of the QPO signals, we employed two methods: Lomb-Scargle periodograms and Weighted Wavelet Z-transform. Both of these different methods yielded consistent results. \textcolor{red}{\sout{The results showed signals with day-timescale QPO in sectors 20, 26, 53, and 73, with confidence levels exceeding $3\sigma$, and three of the sectors exhibited a ~3.8 days QPO. To explain these rapid quasi-periodic changes, we discuss several possible explanations. We propose that the QPO signal might be due to the rotation of hot spots on circular orbits within the accretion disk.}}\textcolor{blue}{The results show that QPO signals exist in sectors 20, 26, and 53, with the confidence levels exceeding 99.73%. The QPOs in sectors 20 and 26 are $\sim 3.8$ days and have a global significance of 95%. To explain these rapid quasi-periodic variations, we discussed several possible physical scenarios. The most possible one is the kink instability in relativistic jets. The other possible scenario is the rotation of hot-spots in the innermost accretion disk. Based on the hot-spot orbital model hypothesis, the mass of the black hole at the center of this BL Lac object wes estimated. The validity of these two explanations requires further observational data to verify. However, since the radiation of BL Lac objects primarily originates from jets, we prefer the kink instability in relativistic jets to be the cause of this rapid QPO.
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All authors Xin-Shun Jin, Ting-Feng Yi, Yangwei Zhang, Yuncai Shen, Junjie Wang, Lisheng Mao, Liang Dong

High Energy Astrophysical Phenomena

Radio-Gamma-Ray Properties and High-Energy Implications for Fermi Blazars

Xu-Hong Ye, Wen-Xin Yang, Guo-Hai Chen et al. (+5 more)

Radio and $\gamma$-ray emissions in blazars, a subclass of active galactic nuclei (AGNs), provide important insight into their high-energy radiation processes. We studied the relation between radio and $\gamma$-ray emissions using a large sample of 1687 Fermi blazars, based on the Radio Fundamental Catalogue and the latest Third Data Release of the Fourth Fermi AGN Catalogue. A clear correlation between radio and $\gamma$-ray fluxes for both BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs) suggests a synchrotron self-Compton (SSC) contribution to both subclasses. The ratio of $\gamma$-ray and radio emissions, $\gamma$-ray loudness ($G_{\rm r}$), is further examined with the $\gamma$-ray photon index ($\Gamma_\gamma$) and the synchrotron peak frequency ($\nu_{\rm{peak}}$). An anti-correlation between $G_{\rm r}$ and $\Gamma_\gamma$ is explained by the shift of the spectral energy distribution rather than the Compton cooling effect. We found that $G_{\rm r}$ shows a positive dependence on $\nu_{\rm{peak}}$ for low-synchrotron-peaked BL Lacs (LBLs) and FSRQs, in line with the SSC-contributed scenario, although additional external Compton contributions may account for the substantial scatter observed in LBLs and FSRQs. In contrast, high-synchrotron-peaked BL Lacs (HBLs) reach the plateau of $G_{\rm r}$ between $\log (\nu_{\rm peak}/{\rm Hz}) \simeq15.5-16$, possibly indicating the transition from the Thomson to the Klein–Nishina (KN) regime. Interpreting this feature within a one-zone SSC framework could constrain the magnetic field strength of $-4.14 < \log (B/{\rm G}) < -1.69$ for those HBLs affected by the KN suppression.
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All authors Xu-Hong Ye, Wen-Xin Yang, Guo-Hai Chen, Zhi-Yuan Pei, Yong-Yun Chen, Yi Liu, Denis Bastieri, Jun-Hui Fan

Earth and Planetary Astrophysics

Öpik-type collision frequency for Kozai-driven projectiles: Target bodies on inclined circular orbits

Youpeng Liang, Junhai Huang and Xiaodong Liu

Existing Öpik-type collision-frequency methods already incorporate the Kozai-driven secular evolution of the orbital elements of high-inclination projectiles. However, these methods generally assume that the target body's orbit lies in the reference plane defined by the orbital plane of the perturbing body. The present paper extends the semi-analytical framework developed by Vokrouhlický et al. (2012) for a target body on a circular orbit in the reference plane to the case of a target body on a circular orbit with a non-zero inclination relative to that plane. The target body's nodal precession rate is prescribed to be constant and may be zero. In this geometry, whether the two orbits intersect depends not only on the secular state of the projectile's orbit but also on the relative nodal longitude between the two orbits. To account for this dependence, the relative nodal longitude is introduced as an additional geometrical variable, and the framework is extended accordingly. When the target body's circular orbit lies in the reference plane, the present formulation analytically reduces to the zero-inclination case described by Vokrouhlický et al. (2012). The numerical results also confirm this reduction. For the two cases with inclined target-body orbits, the collision frequencies computed with the present framework are used to predict semi-analytical decay curves for the fraction of projectiles remaining. These predicted curves closely match those obtained from direct dynamical simulations.
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Astrophysics of Galaxies

VLT/MUSE Study of Close AGN Pairs and Host Galaxies in the Local Universe. I. Overview of the Ionized Gas

Xiaoyu Xu, Zhiyuan Li, Meicun Hou et al. (+3 more)

Studying AGN pairs and their host galaxies is essential for understanding the interplay between galaxy mergers and key internal processes such as supermassive black hole fueling and feedback. We cross-match between the Big Multi-AGN Catalog (The Big MAC) and the public data archive of the VLT/MUSE, and obtain 12 AGN pair candidates in the local universe ($z\lesssim0.1$) with a projected distance $r_{\rm p}\leq 20\rm\,kpc$. Using the archival VLT/MUSE data, we present a spatially resolved study of the ionized gas kinematics and ionization properties of these 12 AGN pair candidates. By decomposing the optical emission lines into two Gaussian components, we try to separate gas associated with disk rotation from non-circular motions. We further identify dominant ionization mechanisms using spatially resolved BPT diagnostics. We find that both nuclei in 4 of the 12 systems are classified as Seyfert or LINER. In addition, three nuclei are classified as star-forming or composite in the optical diagnostics, but are identified as AGNs at other wavelengths. Kinematically, regularly rotating ionized gas disks are detected in 16 of 24 nuclei. Prominent tidal features traced by ionized gas are also detected in 9 systems. Ionized gas outflows are widespread and are detected in 18 nuclei. Finally, for three nuclei (Mrk 739A, NGC 7592B, and J1544+0446A), we find evidence for fading AGN activity over the past several $10^{4}\rm\, yr$, based on optical emission-line ratios and an assumed AGN photoionization model.
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All authors Xiaoyu Xu, Zhiyuan Li, Meicun Hou, Junfeng Wang, Fuyan Bian, Yan-Mei Chen

Solar and Stellar Astrophysics

First monitoring campaign of a Main-sequence Radio Pulse emitter: the case of CU Vir

Barnali Das, Hayley Bignall, Andrew Zic et al. (+6 more)

CU Vir, a magnetic hot star, is the first discovered Main-sequence Radio Pulse emitter (MRP) characterized by its ability to produce periodic radio pulses via electron cyclotron maser emission. Although significant advancements have been made in understanding MRPs, their temporal properties remain mostly unexplored. To overcome this limitation, we conducted a pilot study with the Australia Telescope Compact Array, in which we observed pulses from CU Vir at 36 epochs over $1-3$ GHz. In this frequency range, CU Vir produces two $\approx 100\%$ circularly polarized pulses, called `leading' and `trailing' pulses per rotation period. We find significant differences in the variability indices exhibited by the two pulses as a function of frequencies, with the leading pulse showing higher variability throughout our observing band. This result could be explained in the scenario of centrifugal breakout events in the magnetosphere of an oblique rotator causing correlated fluctuations across frequencies, along with intrinsic instabilities associated with coherent emission. In addition, we discover jittering in the arrival phases of pulses that must be considered in future monitoring campaigns. The pulses also exhibit a systematic shift to later arrival times during the course of our observing campaign, allowing us to refine the rotation period to $0.5206882$ days. Finally, we estimate that $\sim 30$ pulses will be needed to extract global pulse properties for the leading or trailing pulses. This relatively small number strongly motivates more extensive monitoring campaigns of MRPs, both to validate our results, and also to pinpoint the origin of the observed temporal variations.
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All authors Barnali Das, Hayley Bignall, Andrew Zic, Poonam Chandra, Joshua Pritchard, John Morgan, Ankita Ghosh, Bhaswati Bhattacharyya, George Hobbs

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Unified remnant models for aligned-spin, precessing, and eccentric binary black hole mergers

Tousif Islam, Digvijay Wadekar and Gaurav Khanna

Using approximately $5000$ numerical-relativity (NR) simulations spanning mass ratios up to $q=128$ and $1200$ black-hole-perturbation-theory (BHPT) simulations extending to $q=1000$, we present fully analytic models for the remnant properties of quasi-circular binary black hole mergers. The models gwModelRemS (for final mass, final spin, peak luminosity, and recoil kick) and gwModelRemP (for final mass, final spin, and peak luminosity) describe nonprecessing and precessing binaries, respectively. Our approach combines analytic insights from post-Newtonian theory and point-particle limits with a data-driven fitting framework which also includes validation-guided AI-agent-assisted optimization. The resulting fits outperform existing analytic models and achieve accuracies comparable to data-driven models within their domains of validity. We also construct gwModelRemP\_flow, a normalizing-flow model for recoil kicks from precessing binaries, marginalized over the in-plane spin orientations. This model additionally utilizes an enlarged low-fidelity training set, beyond the available NR and BHPT simulations, constructed through a waveform-based data-augmentation procedure. We also include simple eccentric extensions through leading-order dependence on eccentricity and orbital anomaly. The models span the equal-mass to extreme-mass-ratio regimes and are publicly available through the gwModels package for applications in gravitational-wave astronomy, astrophysical population studies, and cosmology.
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Cosmology and Nongalactic Astrophysics

Measurement of the Hubble constant with high-energy neutrinos

Gonzalo Herrera, Nicholas Kamp and Carlos A. Argüelles

Measuring distances in the Universe is one of the hardest problems in physics and astronomy. Almost every distance probe relies on photons, whose propagation across cosmic distances introduces extinction, absorption, scattering, and radiative-transfer effects. Neutrinos suffer none of these and propagate unattenuated through dust, intergalactic medium, and dense source environments alike. We introduce a new distance-ladder method for measuring the Hubble constant $H_0$ using high-energy astrophysical neutrinos from point sources as standardizable candles, and report its first observational realization. Using 12 X-ray-selected Seyfert galaxies for which IceCube reports significant per-source neutrino excesses in its 14-year public point-source release, we exploit the disk-corona correlation $L_\nu = \kappa\, L_X^\beta$ between neutrino and X-ray luminosities to construct a neutrino distance ladder anchored by non-redshift distances to NGC 1068 (Cepheid + TRGB). We find $H_0 = 49^{+40}_{-30}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$ and $\beta = 0.67^{+0.16}_{-0.25}$ (68% credible intervals), with the corona slope disfavoring the calorimetric limit $\beta = 1$ at ${\sim}2\sigma$. The result is consistent with existing $H_0$ determinations from Planck and SH0ES within 1$\sigma$. While the uncertainty on $H_0$ is large, the measurement is free of electromagnetic propagation systematics and demonstrates the viability of neutrinos as a novel cosmographical probe.
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Astrophysics of Galaxies

The HII Regions' Molecular Law of Star Formation

Daniela Calzetti, Drew Lapeer, Robert C. Kennicutt et al. (+28 more)

We combine imaging data from the HST, JWST, and ground-based millimeter facilities to investigate the correlation between star formation rate (SFR) and molecular gas at the ~100 pc scale of HII regions in three nearby galaxies: NGC628, NGC5194 and NGC5236. The JWST 21 micron maps of the three galaxies offer a unique insight into the dust-absorbed SFR at high resolution. We find that the relation between the surface densities of SFR and molecular gas has a slope of ~1.85, in log-log scale, significantly steeper than previous results for nearby galaxies but closer to the trends found for molecular clouds in the Milky Way. The steep relation also holds on larger, ~500 pc, scales, and results from the high-resolution imaging that cleanly isolates the star-forming region emission from the underlying galaxy's diffuse contribution. The diffuse emission at 21 micron is, in fact, found to correlate with the galaxy's stellar mass. Comparisons with physical models of star formation are inconclusive; they overlap with the locus of the 100 pc data, but have difficulties in reproducing the data scatter. Possible exceptions are models that add a power law tail to the gas density probability distribution, due to the large range of free parameters allowed. We find that local HII regions, high redshift star-forming clumps, and low and high redshift starburst galaxies form a single sequence of star formation over three orders of magnitude in gas surface density.
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All authors Daniela Calzetti, Drew Lapeer, Robert C. Kennicutt, Bruce Elmegreen, Sean T. Linden, Mark R. Krumholz, Angela Adamo, Daniel A. Dale, Karin Sandstrom, Giacomo Bortolini, Michele Cignoni, Matteo Correnti, Ana Duarte-Cabral, Helena Faustino Vieira, John S. Gallagher, Kathryn Grasha, Mark Heyer, Leslie K. Hunt, Kelsey E. Johnson, Ralf S. Klessen, Thomas S.-Y. Lai, Desika Narayanan, Goran Ostlin, Alex Pedrini, Elena Sabbi, John-David T. Smith, Linda J. Smith, Monica Tosi, Varun Bajaj, Martha Boyer, Tony D. Weinbeck

Cosmology and Nongalactic Astrophysics

Sensitive 3mm Imaging of Discrete Sources in the Fields of X-ray-Selected Galaxy Clusters

Simon R Dicker, Mark Devlin, Luca Di Mascolo et al. (+9 more)

In this paper, we present the results of a blind survey for compact sources in 138 galaxy clusters from the eFEDS X-ray survey. Of these clusters, 96 are new observations. These targets have X-ray mass estimates and redshifts that formally place them above the thermal Sunyaev-Zel'dovich effect (tSZ) survey limits from the Atacama Cosmology Telescope (ACT, DR5), yet were not detected. Compact sources with apparent locations close to (<104") the center of a galaxy cluster can in-fill the tSZ flux decrement, resulting in tSZ surveys missing clusters. To quantify the number of missing clusters from ACT, we carried out a survey at 90GHz using MUSTANG2 on the Green Bank Telescope and achieved a 5-sigma detection limit of 1mJy in the center of each cluster. We detected 11 discrete sources, which when scaled, is slightly lower than our previous tSZ selected sample, M2-ACT (8.0% vs 9.9%). All had radio counterparts. However, unlike the M2-ACT sample, the sources in X-ray selected clusters were concentrated closer to the cluster centers. When their effect on the measured tSZ signal is taken into account the sources we found would result in 4.5% of clusters being missed by tSZ surveys - a result similar to the estimate in recent ACT results. Most of the 96 clusters in eFEDS but not in ACT are a result of noise and overestimation of mass from X-ray measurements.
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All authors Simon R Dicker, Mark Devlin, Luca Di Mascolo, Saianeesh Haridas, Matt Hilton, Joshiwa van Marrewijk, Brian S. Mason, Emily Moravec, Tony Mroczkowski, John Orlowski-Scherer, Charles Romero, Craig Sarazin

Saturday 1 August

Instrumentation and Methods for Astrophysics

Black Hole Explorer Mission Development in Japan

Kazunori Akiyama, Mareki Honma, Akihiro Doi et al. (+21 more)

The Black Hole Explorer (BHEX) is a next-generation space very-long-baseline interferometry (VLBI) mission concept that will extend existing ground-based millimeter/submillimeter VLBI arrays to space. The Japanese astronomical community has contributed to BHEX mission development through the BHEX Japan Consortium, established in 2023. This paper provides a high-level summary of progress in Japan since 2024, including the establishment of the Black Hole Explorer Working Group (BHEX WG) at the Institute of Space and Astronautical Science (ISAS), JAXA, to conduct the Japanese side of the Pre-Phase~A mission studies. We outline recent advances in key instrument technologies, including concept design studies of a 4.5\,K closed-cycle mechanical cryocooler and prototype development of an ultra-wideband 300\,GHz Superconductor–Insulator–Superconductor (SIS) mixer for BHEX. We also describe ongoing upgrades to Japan's ground infrastructure to support 86\,GHz observations with VERA and simultaneous 86+230\,GHz observations with the Nobeyama 45\,m Telescope.
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All authors Kazunori Akiyama, Mareki Honma, Akihiro Doi, Shoko Koyama, Kotaro Niinuma, Kazuhiro Hada, Yuto Akiyama, Rebecca Baturin, Peter Galison, Paul Grimes, Yoshiaki Hagiwara, Takayuki J. Hayashi, Aya E. Higuchi, Janice Houston, Michael D. Johnson, Tomohisa Kawashima, Daniel P. Marrone, Yosuke Murayama, Ken Ohsuga, Hannah Rana, Hidetoshi Sano, Edward Tong, Yuh Tsunetoe, Yoshinori Uzawa

High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Scalaron-driven Dark Matter during Warm Inflation via UV Freeze–in

F. Millo

We investigate the production of Dark Matter (DM) within the warm Higgs–Starobinsky (HS) inflation. By adopting the ultraviolet (UV) freeze–in mechanism – where the DM number density is initially negligible but is populated over time through non-renormalizable interactions of defined mass dimensions – we find that the DM production within the HS potential has a characteristic timing. For both DM masses, $m_\chi=1$ MeV and $m_\chi=100$ GeV, the yield of DM occurs close to the termination of inflation and its transition to the radiation dominated (RD) era. The present–day DM relic abundance is generated for both DM masses with non-renormalizable operators of mass dimension $D=\{8,9\}$ within strong dissipation regimes. The obtained results suggest that the form of the HS potential and the associated scalaron dynamics favor UV freeze–in DM production as the scalaron approaches the minimum of the potential, where energy transfer to the thermal bath becomes particularly efficient. This distinctive transition behavior differentiates the HS model from other inflationary models and advances our understanding of DM production.
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Instrumentation and Methods for Astrophysics

Qualification pathways for Photonic Integrated Circuits in Astrophotonic Space Missions

Kalaga Madhav, Aashia Rahman and Máté Ádámkovics

Photonic integrated circuits (PICs) promise order-of-magnitude reductions in the size, weight and power (SWaP) of optical subsystems for astronomy, planetary and Earth-observation missions, yet no PIC-specific space-qualification standard exists. This paper consolidates the principal NASA and ESA qualification documents that apply, or can be tailored, to astrophotonic PICs — arrayed waveguide gratings, photonic lanterns, fibre Bragg gratings, and integrated beam combiners (ABCD, discrete beam combiners, nullers) for spectrographs and stellar interferometers. A master qualification table lists 19 standard test steps with applicable standards and EU/USA test facilities. Two reference mission profiles — a LEO smallsat demonstrator and an HWO-class Lagrange-2 flagship — yield a tailoring matrix, while a TRL-versus-test-coverage roadmap maps each activity onto the NASA/ESA readiness levels and review gates. A survey of UV/visible/near-infrared platforms relates spectral coverage, maturity and flight heritage, and a radiation-effects summary shows passive silica, Si3N4 and laser-written cores are essentially radiation-tolerant while active III–V and Ge devices carry the hardness burden. The central outcome is a seven-phase qualification template (PIC-SQT) with explicit TRL gates, exact test procedures and mission-class tailoring; we further identify qualification processes relevant to PICs that current standards do not cover, and document 40+ years of optical-fibre flight heritage.
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Cosmology and Nongalactic Astrophysics

Progenitor age-bias-corrected Type Ia supernovae favor a logarithmic luminosity-distance relation

Hoang Ky Nguyen

Type Ia supernovae provide one of the principal observational probes of late-time cosmic acceleration. Recently, Son et al. [MNRAS 544, 975 (2025)] proposed that correlations between SNe Ia luminosity and progenitor age could introduce a systematic bias in the inferred luminosities, leading to revised distance moduli in the Pantheon+ and DES-SN5YR compilations. Motivated by this possibility, we test whether the age-bias-corrected SNe Ia Hubble diagrams comply with the luminosity-distance relation $d_L=c/H_0\,(1+z)\ln(1+z)$. We find that this one-parameter logarithmic relation provides a high-quality description of both datasets, with the Hubble constant $H_0$ as its sole free parameter. For Pantheon+ and DES separately, the relation yields lower $\chi^2$ values than the two-parameter flat $\Lambda$CDM, with $\Delta\chi^2=12.0$ and $2.1$, respectively. A joint likelihood analysis of both datasets yields $\Delta\chi^2=17.1$, corresponding to $(\Delta\text{AIC},\Delta\text{BIC})=(19.1,25.2)$ in favor of the logarithmic relation. We further find that, after the age-bias correction, neither dataset requires higher-order corrections to the relation, whereas the Einstein-de Sitter cosmology is firmly rejected. These results indicate that the closed-form relation $d_L=c/H_0\,(1+z)\ln(1+z)$ provides a viable one-parameter description of progenitor age-bias-corrected SNe Ia Hubble diagrams. Its asymptotic behavior $d_L\propto z\,\ln z$ naturally accounts for the excess distance moduli observed at high redshift. Should the progenitor age-bias correction be confirmed, the logarithmic relation can be stringently tested using larger samples of SNe Ia within $1\lesssim z\lesssim2$, where it already departs markedly from flat $\Lambda$CDM.
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Instrumentation and Methods for Astrophysics

webSME: An online tool to infer stellar parameters and abundances

Johannes Puschnig, Andreas J. Korn, Jonathan Remmert et al. (+3 more)

Stellar spectroscopy is a robust technique for determining fundamental stellar parameters such as effective temperature, surface gravity and metallicity. Spectroscopy Made Easy (SME) has long served as a framework for spectral synthesis and parameter inference. In this paper, we introduce webSME, a web-based extension of the Python implementation of SME. webSME integrates enhancements including a non-local thermodynamic equilibrium abundance correction mode, a precomputed grid of synthetic spectra for robust determination of stellar parameters from large wavelength ranges (thousands of Angstroms wide), Markov Chain Monte Carlo sampling for uncertainty estimation, and support for recent reference abundance patterns. It enables efficient and user-friendly analysis of high-resolution spectra, making it suitable for a wide range of applications - from detailed abundance studies to education and outreach. We demonstrate the performance of webSME on synthetic and observed spectra, including benchmark stars, and validate its accuracy against classical SME-based analysis. The platform's ease of access and advanced capabilities position it as a powerful tool in the modern astrophysical toolkit.
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All authors Johannes Puschnig, Andreas J. Korn, Jonathan Remmert, Ivy Balkwill-Western, Chi Than Nguyen, Nikolai Piskunov

High Energy Astrophysical Phenomena

Submillimeter Detectability of Gravitational-Wave Counterparts from Neutron-Star Mergers with the Xue-shan-mu-chang 15-meter Telescope

Di Xiao

Submillimeter (sub-mm) follow-up of binary neutron star (BNS) mergers provides unique constraints on the early-time energetics and environments of relativistic outflows, capturing the spectral evolution at epochs where centimeter-band emission is often still optically thick or yet to peak. However, the practical scientific yield depends on instrument-specific thresholds, the observing cadence, and the distinct temporal contributions from isotropic ejecta versus beamed relativistic jets. With the upcoming Xue-shan-mu-chang 15-meter SubMillimeter Telescope (XSMT), facility-specific forecasts are needed to test for sustained engine energy injection, as expected for a long-lived magnetar remnant rather than a promptly formed black hole. We present a unified numerical framework that couples engine-driven ejecta dynamics to non-thermal synchrotron emission, accounting for synchrotron self-absorption and deep-Newtonian effects. Adopting fixed 5$\sigma$ (1 h) point-source thresholds of 1.5/2.9/10.2 mJy at 230/345/460 GHz, we construct parameter-space detectability maps and estimate event rates based on current BNS merger-rate priors. For a fiducial local event at 40 Mpc, we find that a magnetar-boosted ejecta afterglow peaks on timescales of weeks to months and remains detectable long enough to allow delayed follow-up, with an expected all-sky rate of $\dot N_{\rm ej} \approx 0.05$–1.7 yr$^{-1}$ at 230 GHz for $f_{\rm mag}=1$; this rate is an upper limit and scales linearly with the long-lived magnetar fraction. Conversely, while relativistic jets produce intense early-time signals, their detection is constrained by narrow beaming and fleeting visibility. Our framework provides a quantitative basis for prioritizing gravitational-wave triggers and maximizing the scientific yield of XSMT in the multi-messenger era.
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Instrumentation and Methods for Astrophysics

Conceptual architecture of the detector infrastructure for WST

A. Meoli, O. Iwert, E. George et al. (+5 more)

The Wide-field Spectroscopic Telescope (WST) is a proposed 12 m wide-field spectroscopic facility combining several multi-object spectrographs. It requires a yet unprecedented number of detectors. In this paper we present conceptual architecture for the detector controller and infrastructure required to operate a large number of detectors, potentially applicable to WST, focusing on the system-level, power distribution, and the associated data handling. We also consider how these elements may evolve over the expected development timeline of such a facility. Motivated by the scale of the problem, we outline a possible distributed detector-controller architecture, based on modular units placed close to the detectors and networked backend electronics.
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All authors A. Meoli, O. Iwert, E. George, O. Squalli, M. Richerzhagen, A. Rüde, M. Seidel, S. Lévêque

Astrophysics of Galaxies

Supernova feedback in porous photoionized Giant Molecular Clouds

Cheryl S. C. Lau, Ian A. Bonnell, Yueh-Ning Lee et al. (+1 more)

We present a new suite of numerical simulations of Type II supernovae (SNe) detonating in Giant Molecular Clouds with a variety of density structures shaped by photoionization feedback. Ionizing radiation sculpts cavities and channels that guide SN energy to emerge from the cloud as shock-driven blowouts, rather than as a coherent spherically expanding shell as assumed in most sub-grid SN models adopted in galaxy or cosmological simulations. We investigate how such outflows differ to the 1-D descriptions, and whether or not the perturbations induced by the blowouts are sensitive to the host cloud's structure. A channelling parameter $P_\mathrm{chnl}$ is introduced to characterise the cloud's porosity and boundness using the morphology of the ionized channels. Our results reveal that the outflow velocities, whilst consistently higher than that of the spherical blasts, are in fact rather independent of the porosity of its local environment. The total kinetic energy and momentum deposited also appear similar across all runs. What is most sensitive to $P_\mathrm{chnl}$ is the mass of the materials carried in the outflows and their migration distances. It implies that SNe exploding in compact clouds with distinctive channel structures may have more confined metal injection radii and shortened turbulent driving scales, which consequently lead to a clumpier interstellar medium with higher density and metallicity fluctuations. We argue that molecular cloud structures play an equally important role to SN rates and energy budgets in stellar feedback sub-grid modelling.
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All authors Cheryl S. C. Lau, Ian A. Bonnell, Yueh-Ning Lee, Ke-Jung Chen