Instrumentation and Methods for Astrophysics
An empirical calibration of the spectral resolution of JWST NIRSpec PRISM
Hang Zhou, Xin Wang, Yuxuan Pang et al. (+4 more)
We present an empirical calibration of the effective spectral resolution of the JWST NIRSpec PRISM disperser based on a large sample of
galaxies drawn from archival observations. Our sample spans a wide
redshift range, $0.5 \lesssim z \lesssim 10$, enabling a wavelength-dependent characterization of the PRISM resolving power across the full bandpass using the [O III]$\lambda\lambda4959,5007$ doublets. To ensure robust measurements, we impose strict signal-to-noise requirements on both continuum and emission-line detections. Emission-line profiles are fitted with multi-Gaussian models, and the full width at half maximum (FWHM) is measured for each source. The derived empirical resolution curve shows a systematic offset from the nominal pre-launch estimate, lying between the tabulated instrumental resolution and the point-source shutter limit. We also discuss how source size affects the final spectral resolution, and provide an analytical formula that combines wavelength and morphology dependence in a root-sum-square framework. This work delivers a population-averaged, statistically robust calibration of the effective PRISM spectral resolution for typical
galaxy observations. The resulting calibration is directly applicable to statistical analyses of
galaxy spectra obtained with NIRSpec PRISM. Our empirical calibration exceeds the pre-launch JDox values by a factor of 1.03 to 1.63, depending on source morphology, and provides the first wavelength and morphology dependent calibration of the NIRSpec PRISM spectral resolution.
Read the full abstract ▾
All authors Hang Zhou, Xin Wang, Yuxuan Pang, Shengzhe Wang, Karl Glazebrook, Themiya Nanayakkara, Hu Zhan
Earth and Planetary Astrophysics
Fermentation heterotrophy can reproduce Enceladus's plume H2 and CH4 under limited serpentinization
Sam Nasreldine, Antonin Affholder, Laura Molares Moncayo et al. (+2 more)
Saturn's icy moon Enceladus is a
prime target in the search for life beyond Earth. Abundant H2 and CH4 in Enceladus's south-polar plume have been shown to be consistent with hydrogenotrophic methanogens feeding on products of long-lived serpentinization. However, thermo-permeability models make sustained core-wide H2 production by serpentinization uncertain. We therefore explore whether an alternative metabolism based on fermentation-driven heterotrophy could reproduce Cassini H2 and CH4 escape fluxes under limited serpentinization. We develop a coupled ecosystem model of fermentation and methanogenesis in a hydrothermal-ocean-plume framework, using glycine as a proxy for amino-acid-like fermentable organics. With effectively no abiotic H2 and CH4 input, purely heterotrophic communities with fermenters and methanogens can reproduce both Cassini-derived flux intervals given sufficient hydrothermal glycine-equivalent supply, while the estimated organic stock could sustain the required H2 production on gigayear timescales if fully available. We then test a scenario with input ranges for fermentable organic matter, H2, and CH4 informed by asteroid-sample measurements and geochemical estimates of limited serpentinization. Simulations within both Cassini-derived flux intervals are concentrated in communities with acetoclastic methanogens;
Bayesian model comparison favors the same communities. This holds even allowing for greater abiotic H2 and CH4 inputs that reduce the fermentable-organic supply required to reproduce the plume. We therefore identify fermentation heterotrophy as a testable alternative to purely hydrogenotrophic, serpentinization-dominated biotic interpretations and motivate future plume searches for co-exported fermentation products, including acetate and ammonium, together with measurements of methane carbon isotopes.
Read the full abstract ▾
All authors Sam Nasreldine, Antonin Affholder, Laura Molares Moncayo, Régis Ferrière, François Guyot
Cosmology and Nongalactic Astrophysics
Detecting redshift space distortions with forthcoming 21cm intensity maps from MeerKLASS
Daniel Tassie, Steven Cunnington, David Bacon et al. (+2 more)
Redshift space distortions (RSD) provide a powerful measurement of structure formation in modern cosmology. In this work, we explore the potential of 21cm intensity mapping with the MeerKAT Large Area Synoptic Survey (MeerKLASS) to detect RSD and probe
gravity within the
redshift range of MeerKAT's UHF band ($0.4<z<1.45$). Using simulated sky observations, we examine the impact from observational effects caused by blind foreground removal and MeerKAT's primary beam, plus $k$-cuts to the measurements. With a multipole expansion formalism, we demonstrate how the quadrupole of the HI power spectrum can be modelled and also show how a foreground transfer function can reconstruct the distorted signal. With 1,115 deg$^2$ of simulated MeerKLASS observations at $0.4<z<1.0$, our proposed analysis pipeline reveals a $6.7\sigma$ detection of an RSD-induced quadrupole relative to one caused by anisotropic observational effects alone. We also explore parameter inference with the full MeerKLASS 10,000 deg$^2$ survey. Within forecasts, we demonstrate how a tomographic analysis across the full UHF
redshift range can be leveraged to address certain parameter degeneracies with e.g. the HI bias ($b_{\rm HI}$) and
cosmic density of HI ($\Omega_{\rm HI}$). By adopting a
redshift-dependent model for the bias and HI density combined with simulation-informed priors, we demonstrate how degeneracies can be alleviated, and indicate the potential for MeerKLASS to reach competitive precision on simple probes of modified
gravity.
Read the full abstract ▾
All authors Daniel Tassie, Steven Cunnington, David Bacon, Zhaoting Chen, José Luis Bernal
High Energy Astrophysical Phenomena
Flip-Flop Shocks and Tori in Bondi-Hoyle-Lyttleton Accretion onto Rotating Kerr-Weyl Black Holes and Their Quasi-Periodic Variability
Orhan Donmez, Imtiaz Khan and G. Mustafa
We present GRHD simulations of Bondi-Hoyle-Lyttleton
accretion onto a rotating black hole in Weyl conformal
gravity, described by the Kerr-Weyl metric. The equatorial flow is evolved for
spins a=0.9M and a=0.5M and several Weyl coefficients, which enter through an effective
curvature parameter k, and is compared with Kerr runs sharing the same setup. For the k considered, the horizon, ISCO and test-particle frequencies differ from Kerr by at most ~2%. However, the
curvature term grows as kr^2 and acts at the
accretion radius R_acc. The flow is controlled by one quantity, eta=|k|R_acc^3/M, the ratio of
curvature-induced to Newtonian acceleration at R_acc. For eta<~0.03 a stable shock cone forms, indistinguishable from Kerr. For eta~0.2-0.3 the anti-de Sitter-like term traps shocked gas behind the black hole and drives persistent flip-flop oscillations. For eta>~1.6 the cone is destroyed and an oscillating
torus forms.
Spin modifies only the inner few gravitational radii and does not change the regime. In strongly deviating models the mean
accretion rate is 1.7-3 times the Kerr value and varies by 20-60% rms, versus 0.1-1% in Kerr-like flows. The power spectra show global QPOs with fundamentals at 2.9-4.8 Hz for a 10 Msun black hole, with harmonic ladders whose 3:2 and 2:1 ratios come from one non-sinusoidal oscillation, not resonances. These lie in the low-frequency QPO band and are unrelated to test-particle frequencies (~70-200 Hz). They scale as f_0=xi f_K(R_acc), with xi~0.7-1.1 for stable cones and xi~0.23-0.38 for flip-flop and
torus regimes. Strong oscillations would be detectable within seconds for a bright Galactic source. The required |k| exceeds galactic-rotation-curve values by 18-36 orders of magnitude, so a detected shock-driven QPO would measure a local deviation from Kerr, and its absence would constrain |k|.
Read the full abstract ▾
Astrophysics of Galaxies
The Silk Nebula: A Newly Discovered Giant [OIII] Emission Filament
Yi-Fei Wu, Songyu Jia, Chao-Jian Wu et al. (+14 more)
We report [O\,iii] narrow-band imaging of an extremely large-scale nebula, the Silk Nebula, discovered by the SWONS (Super Wide-Field [O\,iii] Narrow-band Survey), together with multi-fiber medium-resolution spectroscopic data covering the H$\alpha$, [N\,ii], [S\,ii], and [O\,iii] emission lines, acquired with the Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (LAMOST) as part of the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N). Based on 2,684 high-quality spectra, we measured its physical parameters, including relative line intensities, radial velocities (RVs), and full widths at half-maximum (FWHMs). The [S\,ii]/H$\alpha$ ratio of the nebula significantly exceeds the shock-excitation threshold of 0.4. Its location in BPT diagnostic diagrams and spatial morphology of [O\,iii] both support the optical emission is dominated by shock-heated gas. The oxygen abundance is near solar and spatially uniform, consistent with a shock propagating into the ambient interstellar medium. Because [O\,iii] is the only emission line that clearly traces the nebular morphology, we base our distance estimate exclusively on the [O\,iii] kinematics, obtaining a fiducial distance of $\sim$160 pc. At this distance, the nebula has a physical extent of $\sim$28 pc along the north-south direction. We suggest that the Silk Nebula is a large [O\,iii] filament possibly associated with a
supernova remnant, although a diffuse-ionized-gas (DIG) or ionized-bubble origin cannot be ruled out with the present data, and one of the largest angular-scale [O\,iii] emission structures documented to date. Future deep X-ray observations and shock-modeling efforts are required to firmly establish its nature.
Read the full abstract ▾
All authors Yi-Fei Wu, Songyu Jia, Chao-Jian Wu, Chao Zhang, Li-Yue Zhang, Shu Wang, Juan-Juan Ren, Quzhen Dongyang, Hong-Yun Qiu, Zhi-Hong He, Jichen Zhang, Guo-You Sun, Wei-Guo Zhang, Jian-Jun Chen, Hong-Liang Yan, Xiang-Song Fang, Hong Wu
High Energy Astrophysical Phenomena
Extreme mass ratio inspirals from the Hills mechanism, The eccentricity distribution of Hills EMRIs in LISA
Biancamaria Sersante, Davide Mancieri, Kevin Leopoldo Muñoz Zavala et al. (+4 more)
Extreme mass ratio inspirals (EMRIs) are promising sources for future space-based gravitational-wave detectors. We investigate EMRIs produced through the Hills mechanism, in which a stellar-mass black-hole binary (BBH) is tidally separated by a massive black hole (MBH), leaving one component bound to it. We present the first self-consistent modelling of this channel, combining an orbit-averaged Fokker-Planck treatment of the nuclear
star cluster (NSC), three-body modelling of the binary-MBH encounter, Monte Carlo
evolution of captured black holes (BHs), and fully relativistic EMRI trajectories to follow the
evolution from binary supply down to final plunge. We find that Hills EMRIs are substantially more circular than classical EMRIs formed through two-body relaxation. For an MBH of $4 \times 10^6 M_\odot$ and circular, equal-mass BBHs of $20 M_\odot$ with initial separation of $0.1$ AU, EMRI mean eccentricities are approximately $0.097$ at our adopted LISA-band entry threshold and $0.034$ at plunge, compared with $0.478$ and $0.228$, respectively, for classical EMRIs. Of the initial BBHs, approximately $0.4$ per cent become EMRIs, whereas approximately $60$ per cent of captured BHs do. For comparable NSC initial compact-object mass, we find approximately $1.6 \times 10^{-8}$ Hills EMRIs per year per
galaxy, approximately $12$ per cent of the classical EMRI yield. The Hills channel contribution to the overall eccentricity distribution depends strongly on the binary mass fraction in NSCs. We discuss implications for identifying EMRI formation channels with LISA and for quasi-periodic eruptions.
Read the full abstract ▾
All authors Biancamaria Sersante, Davide Mancieri, Kevin Leopoldo Muñoz Zavala, Luca Broggi, Zephyr Penoyre, Elena Maria Rossi, Alberto Sesana
High Energy Astrophysical Phenomena
Resistive alignment of a black-hole magnetosphere
Ruben Lier and Oliver Porth
Recent numerical simulations have shown that black-hole magnetospheres evolve rapidly toward
alignment between the
magnetic axis and
spin axis but the physical origin of this process has remained unclear. We develop an analytic theory of this
alignment within resistive relativistic magnetohydrodynamics. Taking the slow-
spin Blandford-Znajek monopole solution as the exterior
magnetic field, we reduce the induction equation to a relaxation equation for the current-sheet inclination angle. Our analysis shows that
alignment results from second-order
spin effects in the Blandford-Znajek solution combined with explicit resistive dissipation. We test this prediction using resistive-GRMHD simulations at several
spins and resistivities and find a regime in which the measured late-time secular decay agrees quantitatively with the analytic prediction.
Read the full abstract ▾
Earth and Planetary Astrophysics
Towards a coupled activity-fallback model for comets I) 67P/Churyumov-Gerasimenko's water activity from a microphysics model with dynamic dust-depth
Nicholas Attree, Yuri Skorov, Pedro Gutiérrez et al. (+4 more)
We apply a two-layer thermophysical model, with water sublimating from below a dust-crust with dynamically varying depth, to simulate the water outgassing rate, dust-ejections, and non-gravitational forces and torques of comet 67P/Churyumov-Gerasimenko. The dust-depth is determined at each time-step by the balance of dehydration and subsurface pressure, leading to alternating ejections and crust build-up. This model is the first stage of implementing a fully coupled activity-fallback model that self-consistently incorporates dust-fallback into the ejection depth calculation, but already a number of conclusions can be drawn from these results. The two-layer model with only dehydration and ejections is able to reproduce much of the Rosetta outgassing, dust-ejection data and non-gravitational dynamics, particularly in the comet's more primitive southern terrain. Best agreement is found for
nucleus material made up of small aggregates ($d_{agg}\sim1$ mm) with not-too-high dust-to-ice ratios ($\delta\sim2-8$) and low average strengths ($\lesssim1$ Pa) that decreases with depth. Disagreements between the observations and model are greatest for the northern-facing and dust-covered terrains, suggesting the importance of surface modification by fallback and material processing here, which will be the subject of investigation in the next paper.
Read the full abstract ▾
All authors Nicholas Attree, Yuri Skorov, Pedro Gutiérrez, Olivier Groussin, Abhinav Jindal, Raphael Marschall, Samuel P.D. Birch
Earth and Planetary Astrophysics
Combination of multi-observatory photometry to determine asteroid rotation periods
Kristers Nagainis and Ilgmars Eglitis
This study aims to determine asteroid rotation periods from sparse, unevenly sampled, multi-observatory photometry using the Lomb-Scargle (L-S) method. The photometric measurements of the asteroids are taken from the circulars of the Minor
Planet Center (MPC). Twelve asteroids, four of them with known rotation periods, were analyzed with two complementary methods. In the separate
dataset analysis (S-method), each observatory
dataset was analyzed separately, and the final period was obtained as a weighted average of the consistent candidate periods, with weights based on the peak power of the power spectrum, the number of measurements, and the quality of the corresponding light curve fit. In the combined
dataset analysis (C-method), all measurements were corrected for the biases of the photometric band, the
star catalog and the observatory, reduced to a common scale and merged into a single
dataset, after which the period was derived directly from the L-S analysis of the combined time series. Both methods produced consistent results, and they reproduced the known periods of the four test asteroids within 0.05%. The results show that the L-S method is well suited for finding rotation periods in sparse observations with uneven sampling over long time intervals. New rotation periods were found for asteroids 2968, 2971, 3081, 3473, 3716, and 4303. The period of 2968 remains ambiguous because of daily aliasing. For 3716, the most likely period is 10.474 hours, but its daily alias at 13.405 hours cannot be excluded completely. For 3173, the strongest peaks at 22.99 and 45.98 hours are probably daily aliases of a slower brightness variation. For asteroid 2607, the period agrees with a recently published value and is more precise. The approach is therefore promising for automated searches for unknown asteroid rotation periods.
Read the full abstract ▾
Astrophysics of Galaxies
The Population of Type~1 Active Galactic Nuclei in Dark Energy Spectroscopic Instrument. I. Profile-dependent Measurements of the Low-redshift Sample
Zhu-Heng Yao, Wei-Jian Guo, Shuo Zhai et al. (+8 more)
We present a spectral analysis of a large sample of low-
redshift type 1 active galactic
nuclei (AGNs) selected from the first data release of the Dark Energy Spectroscopic Instrument (DESI DR1). For objects at $z\le0.9$, we perform spectral fitting and ML-assisted refinement, yielding 114,754 type 1 AGNs. We use two fitting schemes that differ only in the broad-line model: the broad Balmer components are fitted with either a Lorentzian function or a sum of Gaussians. The continuum and [O III] luminosity measurements agree closely between the two schemes, whereas the Gaussians scheme generally yields larger broad-H$\beta$ full width at half maximum (FWHM) values, larger virial black hole masses, and lower
accretion rates. The adopted broad-Balmer profile also changes the decomposition of narrow Balmer emission. Specifically, the anti-correlation between [O III]$\lambda5007$/narrow H$\beta$ and
accretion rate is stronger under the Gaussians scheme with a Spearman rank correlation coefficient $r_{\rm s}=-0.412$, than under the Lorentzian scheme with $r_{\rm s}=-0.206$; the same tendency is observed in the narrow-line Seyfert 1
galaxies (NLS1s) subset ($r_{\rm s}=-0.435$ and $-0.259$ for the Gaussians and Lorentzian schemes, respectively), suggesting that the Gaussians scheme may provide a more self-consistent separation of the broad and narrow H$\beta$ components. Moreover, the consistent correlations recovered under both profile prescriptions favor a continuous type 1
accretion-state sequence, with NLS1s occupying its high-
accretion end rather than constituting a distinct population.
Read the full abstract ▾
All authors Zhu-Heng Yao, Wei-Jian Guo, Shuo Zhai, Yu-Chang Li, Cheng Cheng, Jun-Rong Liu, Shuang Jin, Antonios Katsianis, Jing Wang, Da-Wei Xu, Jian-Yan Wei
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Binary Ellis-Bronnikov wormholes in 3+1 numerical relativity: mergers, fly-bys and gravitational waves
Nikita M. Shirokov and Ilya Nachevsky
We present what are, to our knowledge, the first 3D numerical-relativity evolutions of wormhole binaries: pairs of massive Ellis-Bronnikov drainholes held open by a ghost scalar field. Each throat is an unstable fixed point whose e-fold time matches the González-Guzmán-Sarbach linear rate to within 1.9%. Two throats obey a charge-sign rule: like scalar charges repel and opposite charges attract, with a measured attraction-to-repulsion ratio of $1.462\pm0.022$ against the predicted 3/2, so only opposite-signed pairs merge. A head-on collision forms a common MOTS around both still-open throats, born with about their combined area. The horizon then loses 28% of its area as it swallows the phantom field, and by $t=100$ lies within 1.4% of the Schwarzschild radius of the pair's mass, still shrinking. Fly-by pairs form no horizon and both mouths inflate, the one nearest capture radiating the most gravitational-wave energy measured. A lone collapsing throat sheds its seeded quadrupole as a burst ringing at the Schwarzschild frequency of the black hole it becomes, and every encounter radiates its own burst of gravitational waves and a scalar dipole of comparable energy and negative sign. A throat survives at most a few orbital periods for any plausible perturbation, and the negative-energy dipole would pump rather than drain the orbit, so these binaries have no inspiral.
Read the full abstract ▾
Earth and Planetary Astrophysics
Detailed study of HD 219134: a benchmark K-dwarf with a compact planetary system
Jérôme Bétrisey, Camilla Pezzotti, Gaël Buldgen et al. (+4 more)
Space missions such as CoRoT, Kepler, and TESS have transformed asteroseismology and its synergies with
exoplanet science. We revisit the nearby K-dwarf HD 219134 to investigate the tension between asteroseismic and interferometric radii, update its fundamental parameters, and reconstruct the rotational,
magnetic, and atmospheric
evolution of the system. We combine forward asteroseismic modeling with seismic inversions to assess systematics from non-seismic constraints, radius measurements, and surface modeling. The revised stellar properties are then used for rotational
evolution, stellar-wind, and high-energy irradiation calculations. Seismic inversions rule out the most recent interferometric radius, while the asteroseismic and spectroscopic results are compatible with the 2019 interferometric measurement. We obtain $M=0.779\pm0.015_\mathrm{(stat)}\pm0.006_\mathrm{(sys)}\ M_\odot$, $R=0.753\pm0.005_\mathrm{(stat)}\pm0.002_\mathrm{(sys)}\ R_\odot$, and an age of $8.92\pm0.89_\mathrm{(stat)}\pm0.19_\mathrm{(sys)}$ Gyr. These systematics include only non-seismic constraints; literature combined uncertainties from physical inputs and surface effects are $0.007M_\odot$, $0.002R_\odot$, and $0.81$ Gyr. Rotational and wind modelling shows that standard
magnetic braking is broadly compatible with the present-day rotation and angular-momentum loss. Weakened braking gives a closer match but challenges standard wind-loss scalings. The inferred X-ray history suggests early stripping of the innermost
planets, while the outer
planets likely retained part of their primordial envelopes; HD 219134d experienced only moderate erosion. The apparent radius discrepancy likely reflects underestimated uncertainties in previous interferometric analyses rather than an astrophysical inconsistency. We advocate adopting the asteroseismic radius, which is robust to modeling assumptions and optimisation strategies.
Read the full abstract ▾
All authors Jérôme Bétrisey, Camilla Pezzotti, Gaël Buldgen, Aline A. Vidotto, Colin P. Folsom, Michaël De Becker, Michaël Gillon
High Energy Astrophysical Phenomena
Simulation Study of Reconstruction of Cosmic Ray Extensive Air Shower with Thermal Neutron Detected by ENDA
Fan-Ping Li, Xin-Hua Ma, Hu Liu et al. (+25 more)
In the investigation of the "knee" region within the
cosmic ray energy spectrum, extensive air shower (EAS) reconstruction by using different EAS secondary particles are of paramount importance for energy determination and composition separation and finally measurement of energy spectrum of different
cosmic ray composition. The Electron-
Neutron Detector Array (ENDA) is designed to detect thermal
neutrons generated in the ground by high energy
hadrons which constitute the "backbone" of EAS and carry vital information regarding the primary
cosmic rays. At present, ENDA-64, consisting of 64 detectors, is employed inside the Large High Altitude Air Shower Observatory (LHAASO). This work simulates the response of ENDA and investigates the lateral distributions of thermal
neutrons. A comparison of the NKG and double-exponential functions for describing this distribution using MC simulation data shows that the double-exponential function is more accurate. The mean difference between fitted and measured thermal
neutron density is within ~ 6%. Meanwhile, the thermal
neutron density at 10 m from the shower axis, $\rho_n$, depends mainly on the sum of all
hadrons energy or the number of high-energy
hadrons. The relationship between $\rho_n$ and EAS
hadron energy or the number of high-energy
hadrons can be well fitted by a linear function on a log scale. This work is fundamental for energy determination and composition separation with hybrid detection by using ENDA in the near future.
Read the full abstract ▾
All authors Fan-Ping Li, Xin-Hua Ma, Hu Liu, Tian-Lu Chen, Shu-Wang Cui, Danzengluobu, Xin-Rui Gao, Wei Gao, Wen-Chao Gao, Hai-Bing Hu, Denis Kuleshov, Kirill Kurinov, Bing-Bing Li, Mao-Yuan Liu, Ye Liu, Igor Maliy, Da-Yu Peng, Yao-Hui Qi, Jia-Bo Qin, Dong Qu, Oleg Shchegolev, Yuri Stenkin, Yu-Sen Wang, Tian-Shuang Yang, Li-Qiao Yin, Hui-Qian Zhang, Liang-Wei Zhang, Shi-Yuan Zhang
High Energy Astrophysical Phenomena
Flux Evolution of PSR B0540–69 and the Spectral Energy Distribution of its Pulsar Wind Nebula
Juan Zhang, Xuezhi Liu, Junyang Zhang et al. (+12 more)
The young Crab-like
pulsar PSR B0540–69, located in the Large Magellanic Cloud, underwent a
spin-down rate transition (SRT) in 2011 December, after which its
pulsar wind nebula (PWN) was reported to brighten up to 2018. In this work, we extend the study of its X-ray and $\gamma$-ray flux
evolution through 2026 by combining observations from multiple X-ray instruments with data from the Fermi Large Area
Telescope, thereby constructing a flux history of the PSR$+$PWN system spanning more than two decades. We find that the enhanced X-ray luminosity of the PSR$+$PWN system has persisted for more than 14 yr after the SRT, up to early 2026, whereas the pulsed X-ray flux remains unchanged across all epochs. This confirms that the brightening originates from the PWN. In the $\gamma$-ray band, neither the pulsed nor the non-pulsed flux shows any detectable long-term variation between 2008 and 2025. Together, these results imply that the additional
spin-down energy released at the SRT has been continuously injected into the PWN over decades, placing strong constraints on the energy budget and physical mechanism of the transition. Combining the non-pulsed X-ray and $\gamma$-ray fluxes measured here with previously published
radio-to-UV data, we further construct a broadband spectral energy distribution of the PWN, which shows properties markedly different from those of the Crab Nebula.
Read the full abstract ▾
All authors Juan Zhang, Xuezhi Liu, Junyang Zhang, Hanlong Peng, Mingyu Ge, Songzhan Chen, Shanshan Weng, Shijie Zheng, Shumei Jia, Chengkui Li, Haisheng Zhao, Ju Guan, Yong Chen, Liming Song, Fangjun Lu
Solar and Stellar Astrophysics
Formation Dynamics of a Rotating Solar Spicule-like Event and Associated Energy-Mass Transport
Liufan Gong, Lei Ni, Guanchong Cheng et al. (+3 more)
We performed three-dimensional radiative magnetohydrodynamic(3D RMHD) simulations in an upward-directed (positive-polarity) open
magnetic field with an initial background strength of 10 G. We identified
vortex-associated spicule-like events and carried out a detailed analysis of one representative event. Prior to the formation of this spicule-like event, a photospheric
vortex appears and twists the
magnetic field lines, then develops upward into higher atmospheric layers, forming a
magnetic tornado system. This event is generated during this process. At the periphery of this
magnetic tornado, twisted
magnetic field lines with negative vertical components reconnect with both external positive-polarity background fields and central positive-polarity fields. The
magnetic reconnection sites rise and rotate together with the developed
magnetic tornado, and many jet-like substructures in this event are closely associated with
plasma upward ejections from these reconnection regions. A vertical force analysis shows that, for this event,
plasma uplift in the photosphere and lower chromosphere is dominated by the pressure-gradient force, whereas in the upper chromosphere, the Lorentz force gradually becomes dominant. At a height of about 4 Mm above the solar surface, this event produces a mean upward mass flux density on the order of $10^{-7}~{\rm kg~m^{-2}~s^{-1}}$ and a mean upward Poynting flux density of approximately $525~{\rm W~m^{-2}}$. The wave-mode decomposition results show that the energy transport associated with the rotational spicule-like event is dominated by the Alfvén mode. Alfvén waves, fast-mode waves, and slow-mode waves carry energy into the lower corona in an approximate ratio of $10:7:3$.
Read the full abstract ▾
All authors Liufan Gong, Lei Ni, Guanchong Cheng, Jiajia Liu, Quan Xie, Robert Erdélyi
Earth and Planetary Astrophysics
Star Cluster Ecology VIII. – Dynamically Forming S-Type and $\alpha$Centauri-like Systems
Erwan Hochart and Simon Portegies Zwart
Aims: To analyse the impact of dynamically formed binaries emerging naturally from various
star cluster environments on already established planetary systems. Methods: Numerical simulations replicating the
star-forming region NGC 1333 are conducted. We consider three models, each using identical cluster realisations and simulation parameters. The cluster itself is initially sub-virial and fractally distributed. Model~A assumes planetary systems are initially in mean motion resonance. In Model~B, the same planetary systems are moved out of resonance, but remain intrinsically stable. Finally, Model~C removes all
planets from the simulation. Ten independent realisations are integrated per model until 30 Myr. Results: Dynamically formed binaries emerge at similar rates across models, indicating
planets play little role in their formation. We also find a higher production rate of wide binaries compared to previous numerical studies which we attribute to the sub-virial and sub-clustered initial conditions. S-type and binary S-type planetary systems naturally emerge in our simulations, while P-type systems are rare. For Model~A, the fraction of S-type or binary S-type systems is f_S=0.02 and $f_Bin,\, S=0.05, respectively. Rogue
planets originating from a binary system are ejected with a substantially larger velocity than those around singletons.
Planet-
star collisions and
planet capture events occur disproportionately within binary systems. Finally, several \alphaCentauri-like systems emerge in our simulations, suggesting that the nearest stellar system to the Sun may have a dynamical origin.
Read the full abstract ▾
Astrophysics of Galaxies
A Relationship Between Fast Radio Burst Dispersion Measure and Host Galaxy Inclination
Lachlan Marnoch, Stuart D. Ryder, Sunil Simha et al. (+9 more)
It is commonly thought that fast
radio bursts (FRBs) trace
star formation, and that they are produced by magnetars. Both hypotheses imply that their sources are hosted primarily (but not exclusively) in galactic disks. Although there is evidence in that direction, it has yet to be shown conclusively. In addition, a tension exists with the fact that at least one FRB source is found in a globular cluster far from the disk of the host. If FRBs originate primarily in disks, the
galaxy orientation could leave an impression in the sample of observed FRBs, either as a selection bias against FRBs in edge-on
galaxies or as a correlation with DMHost. Statistical tests against the inclinations of FRB host
galaxies, derived from parametric morphology applied to optical and near-infrared imaging, can search for these effects. Such a search requires an adequately large sample of known FRB hosts that have been imaged to a sufficient depth, while estimates of DMHost also require the
redshift of each host to be known. These conditions are best met in the Commensal Real-time ASKAP Fast Transient (CRAFT) survey sample of FRB host
galaxies, for which the majority have been imaged at optical wavelengths with FORS2 on the Very Large
Telescope (VLT). Here these data are fitted with the morphology software GALFIT to derive the elliptical axis ratio q (a proxy for inclination) for 34 hosts from the CRAFT sample, detected with ASKAP and followed up with VLT imaging. We find no bias against FRB detections from edge-on
galaxies; instead, we uncover a new relationship between the inclination of an FRB host
galaxy and DMHost. This is consistent with a primarily disk-based origin for CRAFT FRBs. Using this relationship we are able to reduce the scatter of the host sample about the Macquart relation by 40%, demonstrating a new empirical method for estimating DMHost that requires only deep optical imaging.
Read the full abstract ▾
All authors Lachlan Marnoch, Stuart D. Ryder, Sunil Simha, Alexa C. Gordon, R. M. Shannon, Nicolas Tejos, Marcin Glowacki, Ziteng Wang, Elizabeth K. Mahony, J. Xavier Prochaska, Wen-fai Fong, Richard M. McDermid
Astrophysics of Galaxies
Redshifted Cool Gas in the Disturbed HI Disk of the Starburst Dwarf NGC 4214
Shulan Yan, Taotao Fang, Xiaochuan Jiang et al. (+4 more)
We report redshifted cool gas toward the central
star-forming region of the nearby starburst dwarf
galaxy NGC 4214. HST/COS spectra show low-ionization absorbers redshifted relative to the systemic velocity, most clearly in SII ($\Delta v=19.8\pm2.6\ {\rm km\,s^{-1}}$) and supported by MgII ($\Delta v=30.3\pm3.0\ {\rm km\,s^{-1}}$), while PII remains tentative ($\Delta v=7.5\pm3.4\ {\rm km\,s^{-1}}$). The Keck/HIRES spectra also reveal a redshifted CaII absorption component ($\Delta v=25.6\pm1.5\ {\rm km\,s^{-1}}$). Because the absorption is detected against the central UV or optical continuum, the gas must lie in the foreground of the
star-forming region and is moving away from the observer and toward the background UV source in projection. A VLA–THINGS HI spectrum extracted at the COS position within one VLA beam also shows a redshifted neutral component at $v_{\rm hel}=329.2\pm0.9\ {\rm km\ s^{-1}}$, offset by $38.2\pm1.3\ {\rm km\ s^{-1}}$ from systemic and by $27.6\pm1.0\ {\rm km\ s^{-1}}$ from the dominant local HI component. The FAST HI mapping further reveals an extended, kinematically disturbed neutral disk, with residual structures relative to a warped-disk model. Together, the redshifted UV absorption, the redshifted HI component, and the disturbed large-scale HI velocity field show that the central anomalous cool gas is observed in a
galaxy with a disturbed extended neutral disk. This geometry suggests that the redshifted cool gas may trace inflow or recycled fallback toward the central region, although warped-disk or non-circular disk motions cannot be fully excluded.
Read the full abstract ▾
All authors Shulan Yan, Taotao Fang, Xiaochuan Jiang, Junfeng Wang, Qingzheng Yu, Chuanpeng Zhang, Ming Zhu
High Energy Astrophysical Phenomena
ASKAP Monitoring of the Rubin Deep Drilling Fields
Dougal Dobie, James Freeburn, Iris de Ruiter et al. (+5 more)
In the past decade, time domain astronomy surveys across the multi-messenger spectrum have developed "alert streams" which circulate observational information in real-time to the wider astronomical community. Despite this being standard practice for optical, gamma-ray and gravitational wave time domain astronomy for several years now, this kind of infrastructure has not yet been deployed at-scale for
radio telescopes. We are conducting a long-term monitoring program that targets the Rubin Deep Drilling Fields using the Australian SKA Pathfinder (ASKAP). The primary goal of this program is to provide serendipitous
radio observations of all objects of interest in these fields, and circulate that information in as close to real-time as possible. In this manuscript we outline the survey plans and status, the infrastructure we have developed to disseminate this information and an initial data release comprising 5 months of ASKAP observations of each field (although only 3 months overlaps with Rubin) conducted on an approximately 10 day cadence with a noise level of $\sim 60\,\mu$Jy. As part of this data release, we present updated high-cadence
radio light curves to the tidal disruption event AT2018hyz and the
supernova SN2024abfo along with the discovery of two new
radio variables, a possible tidal disruption event ASKAP J095711.5+051205 and an in-progress extreme scattering event ASKAP J005026.4-422958. The scientific results from this program along with the infrastructure developed to acquire them will lay the foundation for the integration of future
radio imaging surveys into the broader multi-messenger alert stream, leading the way for major facilities such as the Schmidt Observatory System and the SKA.
Read the full abstract ▾
All authors Dougal Dobie, James Freeburn, Iris de Ruiter, Katie Auchettl, James Coulson, Brent Miszalski, Anais Möller, Nikhil Sarin
Instrumentation and Methods for Astrophysics
An Ultraviolet Instrument on the Habitable Worlds Observatory: Considerations and Capability Trades on the Multi-Object, Integral-field, and High-resolution modes of a potential UVI
Brian Fleming, Kevin France, Dmitry Vorobiev et al. (+4 more)
The Habitable Worlds Observatory (HWO) is NASA's next-generation astrophysics platform, delivering transformative capability in the search for life and study of the origins of the universe. Amongst the instruments under consideration for HWO is a multi-purpose ultraviolet spectrograph and imager that provides a deep toolbox for some of the most pressing science investigations of the next several decades. In this paper, we present a basic draft model of a potential UVI, including a multi-object spectrograph, far ultraviolet imager, high resolution spectrograph, and integral-field spectrograph. The draft designs for these channels of the UV instrument serve as a basis for a general discussion of the instrument architecture and design challenges, while also identifying potential trades, enhancements, and other considerations that the HWO project will need to address as it moves into the formulation phase. We conclude with a presentation of several scientific simulations that have helped guide the capabilities of the draft design. This paper is intended to serve as a summary of UV instrument modes, technology, and potential design ahead of planned instrument studies in the late 2020's, and then Phase A in the early 2030's.
Read the full abstract ▾
All authors Brian Fleming, Kevin France, Dmitry Vorobiev, Jeanette Donber, Eric Frater, Thomas Delker, Vicki Herde
Earth and Planetary Astrophysics
The Neptunian Final Parsec Problem: How Inertial Waves Enable Neptunes and Gas Giants to Survive Tidal Migration
Tim Hallatt, Adrian J. Barker and Sarah C. Millholland
Observations indicate that some hot Neptunes and Jupiters underwent high eccentricity migration (HEM). A longstanding issue facing HEM theory remains, however: in order to shrink their orbits by ${\sim}1{-}2$ orders of magnitude,
planets must dissipate ${\gtrsim}10{\times}$ more orbital energy than is contained in their structural binding energy. Previous work suggests that excitation of
planets' fundamental modes (”$f$-modes”) at very high eccentricities, $e{\sim}$0.99, can shrink semi-major axes by ${\sim}$an order of magnitude (${\sim}5{\rightarrow}0.5$ au) while safely bleeding tidal energy to space. We examine how
planets traverse the remaining order of magnitude in orbital shrinkage, $a{\sim}$0.5${\rightarrow}$0.05 au, which still poses a danger for Neptunian
planets due to their lower binding energies (their ”final parsec” problem). To assess whether tidally-migrating Neptunes balance their energy budgets, we perform coupled orbit/structure calculations tracking their frequency-dependent tidal response under inertial waves (IWs). We show that tidal radius inflation at moderate eccentricities sweeps Neptunes' fundamental modes back into resonance with tidal forcing; only a small amount of tidal heat relative to a Neptune's binding energy is needed to drive this $f$-mode excitation. This excitation of Neptunes' $f$-modes may offer a route to safe circularization, provided the $f$-mode dissipates without harming the
planet. In contrast, eccentric gas giants ($e{\sim}0.9$) circularize without drama over ${\sim}$Gyr. Our theory predicts that warm Neptunes on a HEM track ($a{\gtrsim}0.1 \ \mathrm{au}, \ e{\gtrsim}0.8$) should be rare, in opposition to warm gas giants and lower eccentricity Neptunes. Observational confirmation of our predictions would constrain the interior structures of Neptunian
planets via tidal theory.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Global analysis of tensor mode helicity
Anna C. Tsai, Dylan L. Jow and Ue-Li Pen
A detection of helicity in a primordial gravitational-wave background (GWB) would provide compelling evidence for parity violation in the early universe and point toward physics beyond the standard picture of inflation. Since big bang cosmology is not time translation invariant, we identify that the so-called “regular” and often-neglected “irregular” solutions are independent degrees of freedom that can in principle carry different, even opposite, helicities. We note that this possibility complicates the interpretation of a measured net helicity. To determine the sensitivity of various GW detector configurations to helicity, we introduce a universal helicity efficiency coefficient that provides a unified
geometric description of helicity sensitivity across gravitational-wave detectors which generalizes and improves previous
estimators. We apply this helicity efficiency coefficient to estimate the sensitivity of a range of future GW experiments to helicity across twenty orders of magnitude in frequency assuming a fully helical background with an amplitude just below the current constraints.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
In-flight Timing Calibration of the Follow-up X-Ray Telescope on Board the Einstein Probe
Juan Zhang, Xiaofan Zhao, Dawei Han et al. (+18 more)
After the launch of Einstein Probe (EP),
pulsars are observed to calibrate the timing system of the onboard Follow-up X-ray
Telescope (FXT) by measuring the times of arrival (TOAs). FXT has two independently operating modules, namely FXTA and FXTB, each equipped with the Wolter-I optics and the pnCCD camera. For scientific observations, each pnCCD has three distinct readout modes that differ in frame cycles, the full frame mode (FF, 50 ms per frame), the partial windowed mode (PW, 2.2 ms per frame), and the timing mode (TM, 23.68 $\mu$s per row, 9.4352 ms per frame). Thus, 1RXS J170849.0–400910 with the
spin period of 11 s is observed in FF, PSR B1509–58 (150 ms) in PW, and Crab
pulsar (33 ms) in TM as well as PSR B1821–24 (3.05 ms) and PSR B1937+21 (1.56 ms). The TOAs of these
pulsars measured by FXTA and FXTB are compared with the results of NICER, and for Crab
pulsar with the Jodrell Bank Monthly Ephemeris (JBE). Results verify that the timing system of FXTA and FXTB in FF, PW, and TM modes are consistent with each other, and are in good
alignment with NICER. The measured advance of the Crab
pulsar's main peak relative to JBE is $357^{\pm14(stat)}_{\pm54(sys)} \mu$s in FXTA and $394^{\pm14(stat)}_{\pm67(sys)} \mu$s in FXTB. Based on measurements of PSR B1821–24 and PSR B1937+21, the preliminary absolute timing accuracy is estimated to be 6 $\mu$s for FXTA and 31 $\mu$s for FXTB in TM mode. Additionally, the systematic delay of FXTA timing results relative to FXTB is found to be $20^{\pm19(stat)}_{\pm21(sys)} \mu$s.
Read the full abstract ▾
All authors Juan Zhang, Xiaofan Zhao, Dawei Han, Hao Wang, Yong Chen, Mingyu Ge, Shijie Zheng, Shumei Jia, Haisheng Zhao, Weiwei Cui, Hanlong Peng, Wentao Ye, Yaoming Duan, Youli Tuo, Zhen Ji, Fuli Ma, Chengkui Li, Ju Guan, Jingjing Xu, Jin Wang, Liming Song
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Direct detection constraints on EFT operators for inelastic dark matter
X. G. Wang and A. W. Thomas
We convert existing exclusion limits on the elastic
spin-independent (SI) dark matter–
proton cross sections into upper bounds on the event rate, subsequently applying them to constrain other effective operators for inelastic scattering of light dark matter in the GeV mass region. We focus on three representative scenarios including the isoscalar,
proton-philic, and the
proton-philic
spin-dependent inelastic dark matter model, which are well-motivated in phenomenological studies of dark matter detection.
Read the full abstract ▾
Astrophysics of Galaxies
Decomposing the Kinematics of SNR G180.0-01.7 with Medium-Resolution Spectra
Juan-Juan Ren, Wei Zhang, Chao-Jian Wu et al. (+3 more)
The exceptionally large angular diameter and intrinsic optical faintness of the Galactic
supernova remnant (SNR) G180.0-01.7 (S147) have historically hindered a comprehensive spectroscopic census of its filamentary structure. We present the first dedicated medium-resolution (R ~ 7500) spectroscopic study of S147 using the LAMOST Medium-Resolution Spectroscopic survey of Galactic Nebulae (MRS-N). By implementing multi-Gaussian decomposition on the H$\alpha$, [NII], and [SII] emission complexes and applying combined spectroscopic and spatial criteria, we disentangle the shock-ionized filaments of the SNR from the pervasive foreground and background Diffuse Ionized Gas (DIG). Our analysis reveals a distinct bimodal radial velocity distribution for the SNR: a low-velocity population tracing the decelerated forward shock at a dense cavity wall, and a high-velocity population (with absolute radial velocities of ~ 70 $\pm$ 30 km/s) corresponding to ejecta within a low-density cavity. The co-existence of these populations provides kinematic evidence for the "
supernova-in-a-cavity" scenario. Furthermore, we detect enhanced [SII]/H$\alpha$ ratios in the DIG along the eastern and northern boundaries of the remnant, signaling shock compression of the ambient interstellar medium and highlighting remnant's multifaceted feedback.
Read the full abstract ▾
All authors Juan-Juan Ren, Wei Zhang, Chao-Jian Wu, Chao Liu, Jian-Jun Chen, Hong Wu