Instrumentation and Methods for Astrophysics
System Analysis for a high-precision high-accuracy Astrometric instrument for HWO
Jérôme Amiaux, Fabien Malbet, Florence Ardellier-Desages et al. (+20 more)
This study presents a comprehensive system analysis for an instrument onboard the Habitable Worlds Observatory (HWO), designed for high-precision, high-accuracy differential astrometry, with the primary scientific goal to determine the mass of Earth-like
planets around the nearest Sun-like
stars. The analysis integrates the definition of the mission profile, the instrumental concept architecture, and an error budget that breaks down the key contributors to the sub-micro arcses precision required for a single measurement. A portion of this budget addresses photo-center estimation for both the target and calibration
stars used in differential astrometry. Other major contributors are related to instrumental control of systematics in the reconstruction of differential angle measurements from pixel data (focal plane calibration) to on sky line of sight (
telescope distortion calibration). End-of-mission astrometry requires multiple observations (typically 100) of the same target distributed over the mission lifetime. We assess the mission profile to estimate the fraction of survey time required for astrometric survey to achieve the science objective. The proposed architecture of the instrument concept is derived from error budget and mission constraints based on a large visible detector array composed of an assembly of multiple CMOS sensor chips resulting in an overall gigapixel focal plane. We evaluate the Technology Readiness Level (TRL) and propose a way forward reaching TRL 5 level for key technologies by the Mission Consolidation Review in 2029.
Read the full abstract ▾
All authors Jérôme Amiaux, Fabien Malbet, Florence Ardellier-Desages, Eric Doumayrou, Pierre-Antoine Frugier, Renaud Goullioud, Thomas Greene, Lucas Labadie, Pierre-Olivier Lagage, Manon Lizzana, Alain Leger, Thierry Lepine, Gary Mamon, Jérôme Martignac, Julien Michelot, Fabrice Pancher, Thibault Pichon, Aki Roberge, Samuel Ronayette, Hugo Rousset, Breann Sitarski, Alessandro Sozzetti, Thierry Tourette
High Energy Astrophysical Phenomena
Analysis and implications of the spatio-spectral morphology of the Fermi Bubbles
Ami Tank, Roland Crocker and Mark R. Krumholz
The
Fermi Bubbles are gamma-ray structures extending from the center of the Milky Way to +/-50 degree
Galactic latitude that were discovered in data obtained by the
Fermi/LAT instrument. Their origin and power source remain uncertain. To help address this uncertainty, here we use a template-free reconstruction of ten years of all-sky
Fermi/LAT data provided by Platz et al. (2023) to carry out a pixel-by-pixel spectral analysis of the Bubbles. We recover the position-dependent spectral shape and normalization that would be required for parent
proton or electron
cosmic ray populations to produce the Bubbles' observed gamma-ray spectra. We find that models in which the gamma-ray emission is driven by either hadronic or leptonic processes can explain the data equally well. The
cosmic ray population driving the emission must have either broken power-law or exponentially cut-off spectra, with break or cutoff energies that are almost constant with latitude but spectral indices below the break that harden towards the Bubbles' southern tip. For the leptonic channel, reproducing the observed position-dependent gamma-ray spectrum also requires a
cosmic ray electron energy density that grows with distance from the
Galactic plane and increases towards the edges of the Bubbles. This finding disfavors scenarios for the origin of the Bubbles where a population of
cosmic ray electrons is accelerated near the Milky Way center and subsequently advected out to the extremities of the Bubbles.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Identifying the physical periods in the radio emission from the $\gamma$-ray emitting binary LS I +61 303
Frédéric Jaron and Valentí Bosch-Ramon
The $\gamma$-ray emitting binary LS I +61 303 exhibits periodic emission across the electromagnetic spectrum, from
radio up to the very-high-energy regime. The most prominent features are the three periods $P_1 = 26.5$ d, $P_2 = 26.9$ d, and $P_{\rm long} = 4.6$ years. Occasionally, a fourth period of 26.7 d is also detected. Mathematically, these four periods are interrelated via the interference pattern of a beating. Competing scenarios that seek to determine which of these periods are physical and which are secondary are under debate. The detection of a fifth period, $P_3 = 26.3$ d, was recently claimed. Our aim is to determine which of these periods are intrinsic (likely related to physical processes) and which of these are secondary (resulting from interference). We avoided any assumption about the physical scenario and restricted our analysis to the phenomenology of the
radio emission variability. We selected intervals from archival
radio data and applied the generalized Lomb-Scargle periodogram. We fit the observational data to generate synthetic data that only contain specific signals. We analyzed these synthetic data to assess the impact of these signals and their interference on the light curves and the periodogram. The two-peaked profile, consisting of $P_1$ and $P_2$, was detected in the periodogram of the actual data for intervals that are significantly shorter than $P_{\rm long}$, provided that these intervals contain a minimum of the long-term modulation. The characteristics of the observational data and their periodogram could only be reproduced with synthetic data if these explicitly included all three periods $P_1$, $P_2$, and $P_{\rm long}$, the residuals being limited by noise. We have found that all three periods, i.e., $P_1$, $P_2$, and $P_{\rm long}$, could correspond to physically real processes occurring in LS I +61 303.
Read the full abstract ▾
Solar and Stellar Astrophysics
A catalog of new blue stragglers in open clusters with Gaia DR3
Songmei Qin, Jing Zhong, Friedrich Anders et al. (+6 more)
The high-precision
Gaia data release 3 (DR3) enables the discovery of numerous open clusters in the Milky Way, providing an excellent opportunity to search for blue straggler
stars in open clusters and investigate their formation and
evolution in these environments. Using the member
stars from literature open cluster catalogs, we visually inspected the color-magnitude diagram (CMD) of each cluster and selected cluster candidates that potentially host blue stragglers. We then reassessed cluster memberships using the pyUPMASK
algorithm with
Gaia DR3 and performed isochrone fitting to derive physical parameters for each cluster, including age, distance modulus, mean reddening, and
metallicity. Finally, we empirically identified straggler
stars based on their positions relative to the best-fitting isochrone, zero-age main sequence (ZAMS), and equal-mass binary sequence on the CMD. In total, we identified 272 new straggler
stars in 99 open clusters, comprising 153 blue stragglers, 98 probable blue stragglers, and 21 yellow stragglers. Compared to the reported blue straggler catalogs based on earlier
Gaia data, our results increase the number of open clusters with stragglers in the Milky Way by 22.2%, and the total number of blue stragglers by 11.2%.
Read the full abstract ▾
All authors Songmei Qin, Jing Zhong, Friedrich Anders, Lola Balaguer-Núñez, Chunyan Li, Yueyue Jiang, Guimei Liu, Tong Tang, Li Chen
Astrophysics of Galaxies
Deep imaging of the very isolated dwarf galaxy NGC6789
Ignacio Trujillo, Sergio Guerra Arencibia, Ignacio Ruiz Cejudo et al. (+3 more)
We present deep optical imaging of the extremely isolated
dwarf galaxy NGC 6789, obtained with the new 2-meter Two-meter Twin
Telescope (TTT3) at Teide Observatory. Despite its location in the Local Void, NGC 6789 exhibits surprising recent central
star formation equivalent to approximately 4% of its total
stellar mass. The origin of the gas necessary for this level of
star formation remains unknown. Our data reach surface brightness limits of 29.8, 29.4, and 28.9 mag arcsec$^{-2}$ in the Sloan g, r, and i filters, respectively, and reveal no evidence of
tidal features or merger remnants down to $\sim$30 mag arcsec$^{-2}$ (or equivalently, at a radial distance larger than 1.6 kpc). The
galaxy's undisturbed outer elliptical morphology suggests that its recent central
star formation was likely produced by either in-situ residual gas or by the
accretion of external pristine gas not associated with a minor merging activity.
Read the full abstract ▾
All authors Ignacio Trujillo, Sergio Guerra Arencibia, Ignacio Ruiz Cejudo, Mireia Montes, Miguel R. Alarcon, Miquel Serra-Ricart
Solar and Stellar Astrophysics
Flares and superflares on the southern active binary CC Eri
M. Leitzinger, P. Odert, R. Greimel et al. (+15 more)
Flares and CMEs are known to be the dominating high-energy phenomena on cool
stars. Superflares were thoroughly investigated using broadband photometry predominantly from Kepler, K2, and TESS. Here we present a spectroscopic investigation of superflares on the very active spectroscopic binary CC~Eri. We focus on spectroscopic signatures of (super)-
flares and line asymmetries with the goal to characterize superflares spectroscopically. In 70 nights of spectroscopic observations obtained at the ESO~1.52m
telescope with the Echelle spectrograph PUCHEROS+ hosted by the PLATOSpec consortium we identified 31
flares from which two are superflares already from the deduced g'-band energies. We also find a broad blue-wing asymmetry occurring in the impulsive phase of another superflare which shows great potential to be a prominence eruption. For the second most luminous
flare we find the largest number of excess emissions during the impulsive and gradual
flare. We identify the
flare to be occurring close to the
stellar limb which indicates that the
flare was even more energetic than derived from its g'-band and spectral line energies. We identify more than sixty spectral lines in the spectral range of 4100 and 7200Å showing excess emission during this
flare. We detect continuum enhancements as well as photospheric line fillings during the
flare. Generally we find that depending on the
flare energy the number of spectral lines revealing excess emission increases, especially for the more energetic superflares. We therefore conclude that superflares are likely scaled-up versions of less energetic normal
flares.
Read the full abstract ▾
All authors M. Leitzinger, P. Odert, R. Greimel, P. Kabáth, J. Lipták, E.W. Guenther, P. Heinzel, P. Gajdoš, M. Ornik, J. Wollmann, M. Skarka, J. Srba, P. Škoda, J. Frýda, R. Brahm, L. Vanzi, J. Janík, P. Pintr
Solar and Stellar Astrophysics
The s Process and Beyond
Maria Lugaro, Marco Pignatari, René Reifarth et al. (+1 more)
Neutron captures produce the vast majority of abundances of elements heavier than iron in the Universe. Beyond the classical slow (s) and rapid (r) processes, there is observational evidence for
neutron-capture processes that operate at
neutron densities in between, at different distances from the valley of $\beta$ stability. Here, we review the main properties of the s process within the general context of
neutron-capture processes and the
nuclear physics input required to investigate it. We describe massive
stars and asymptotic
giant branch
stars as the s-process astrophysical sites and discuss the related physical uncertainties. We also present current observational evidence for the s process and beyond, which ranges from
stellar spectroscopic observations to laboratory analysis of meteorites.
Read the full abstract ▾
All authors Maria Lugaro, Marco Pignatari, René Reifarth, Michael Wischer
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Main Surveys–An Overview of Framework and Simulation Suite
Cheng-Liang Wei, Guo-Liang Li, Yue-Dong Fang et al. (+26 more)
The Chinese Space Station Survey
Telescope (CSST) is a flagship space-based observatory. Its main survey camera is designed to conduct high spatial resolution near-ultraviolet to near-infrared imaging and low-resolution spectroscopic surveys. To maximize the scientific output of CSST, we have developed a comprehensive, high-fidelity simulation pipeline for reproducing both imaging and spectroscopic observations. This paper presents an overview of the simulation framework, detailing its implementation and components. Built upon the GalSim package and incorporating the latest CSST instrumental specifications, our pipeline generates pixel-level mock observations that closely replicate the expected instrumental and observational conditions. The simulation suite integrates realistic astrophysical object catalogs, instrumental effects, point spread function (PSF) modeling, and observational noises to produce accurate synthetic data. We describe the key processing stages of the simulation, from constructing the input object catalogs to modeling the
telescope optics and detector responses. Furthermore, we introduce the most recent release of simulated
datasets, which provide a crucial testbed for data processing pipeline developments, calibration strategies, and scientific analyses, ensuring that CSST will meet its stringent requirements. Our pipeline serves as a vital tool for optimizing CSST main survey strategies and ensuring robust cosmological measurements.
Read the full abstract ▾
All authors Cheng-Liang Wei, Guo-Liang Li, Yue-Dong Fang, Xin Zhang, Yu Luo, Hao Tian, De-Zi Liu, Xian-Ming Meng, Zhang Ban, Xiao-Bo Li, Zun Luo, Jing-Tian Xian, Wei Wang, Xi-Yan Peng, Nan Li, Ran Li, Li Shao, Tian-Meng Zhang, Jing Tang, Yang Chen, Zhao-Xiang Qi, Zi-Huang Cao, Huan- Yuan Shan, Lin Nie, Lei Wang, Zizhao He, Rui-Biao Luo, Quan-Yu Liu, Zhao-Jun Yan
Solar and Stellar Astrophysics
Probing spectral line asymmetries due to the propagating transverse waves in the solar corona
Ambika Saxena, Vaibhav Pant, Tom Van Doorsselaere et al. (+1 more)
Decades-long studies of asymmetric spectral lines in the
solar corona suggest mass and energy transport from lower atmospheric layers to the corona. While slow magnetoacoustic waves and
plasma flows are recognized as drivers of these spectral line asymmetries, the role of transverse MHD waves remains largely unexplored. Previous simulations have shown that unidirectionally propagating kink waves, in the presence of perpendicular density inhomogeneities, can produce a
turbulence-like phenomenon called “uniturbulence”. However, the spectroscopic signatures of this effect have not been investigated until now. Due to varying Doppler shifts from the
plasma elements with different emissions, we expect to observe signatures of both blueward and redward asymmetries. Past instruments like EIS may have missed these signatures due to resolution limitations, but current instruments like DKIST offer a better opportunity for detection. We conducted 3D MHD simulations of transverse waves in a polar plume with density inhomogeneities and performed forward modeling for the Fe XIII emission line at 10749 Å. Our findings show that transverse waves and uniturbulence induce alternating red and blueward asymmetries, with magnitudes reaching up to 20% of peak intensity and secondary peak velocities between 30 and 40 km s$^{-1}$, remaining under 100 km s$^{-1}$. These asymmetries propagate with the transverse waves, and even at DKIST resolution, similar signatures can be detected. Our study suggests that spectral line asymmetries can serve as a diagnostic tool for detecting transverse wave-induced uniturbulence.
Read the full abstract ▾
All authors Ambika Saxena, Vaibhav Pant, Tom Van Doorsselaere, M. Saleem Khan
Cosmology and Nongalactic Astrophysics
Turnover detection using the power spectrum and bispectrum
Yolanda Dube, Bikash R. Dinda, Sheean Jolicoeur et al. (+1 more)
The turnover at the peak of the
Fourier matter power spectrum encodes a fundamental signature of matter-radiation equality in the early Universe. This delivers a potential standard ruler, independent of
baryon acoustic oscillations and therefore able to break parameter degeneracies and improve precision. Furthermore, the turnover scale is independent of
redshift and clustering bias, allowing for stacking of the signals from
redshift bins. In practice, the very large scale of the turnover means that sample variance and systematics are serious impediments to its detection. Detections of the turnover and measurements of its scale have been made in the WiggleZ, eBOSS, Quaia, and DESI surveys. Upcoming surveys should improve the detection significance and reduce errors on the turnover scale. We use MCMC forecasts for turnover detection in a spectroscopic Euclid-like survey and a futuristic MegaMapper-like survey. In addition to the power spectrum, we include the signal from the bispectrum in equilateral configurations. These surveys are forecast to detect the turnover at $\sim\! 6\sigma$ (Euclid-like) and $\sim\! 15\sigma$ (MegaMapper-like), with precision on the turnover scale of $\sim\! 4\%$ and $\sim\! 2\%$. The inclusion of the bispectrum delivers a modest improvement of $\sim\! 10-17\%$ in the constraints on the turnover scale.
Read the full abstract ▾
All authors Yolanda Dube, Bikash R. Dinda, Sheean Jolicoeur, Roy Maartens
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Main Surveys–the Stray Light
Xian Jing-Tian, Lin Lin, Fang Yue-Dong et al. (+9 more)
Stray light significantly influences the detection capabilities of astronomical
telescopes. The actual stray-light level during observations depends not only on the
telescope's inherent stray-light suppression capability but also on its operational orbit conditions. Accurate estimation of stray-light levels is crucial for assessing image quality and performing realistic scientific simulations. To rapidly estimate stray-light levels under realistic, complex operational conditions, we developed an analytical model tailored to the China Space Station
Telescope (CSST). Our model simulates stray-light backgrounds generated by off-field sources such as moonlight, starlight, and earthshine, incorporating the effects of zodiacal light, as well as scattering and ghost images induced by bright in-field
stars. The proposed method allows quick and accurate evaluation of stray-light conditions, facilitating both image simulation and observational scheduling.
Read the full abstract ▾
All authors Xian Jing-Tian, Lin Lin, Fang Yue-Dong, Zhang Xin, Xu You-Hua, Meng Xian-Min, Tian Hao, Zhang Tian-Yi, Ban Zhang, Li Guo-Liang, Xu Shu-Yan, Wang Wei
Earth and Planetary Astrophysics
A Gas-Phase Kinetic Study of the N(2D) + CH3CCH and N(2D) + CH3CN Reactions
Kevin M. Hickson, Jean-Christophe Loison, Benjamin Benne et al. (+1 more)
The chemistry of planetary atmospheres containing molecular nitrogen as a major atmospheric component is strongly influenced by the reactions of atomic nitrogen. Although nitrogen atoms in their ground electronic state N(4S) are mostly unreactive towards stable molecules, electronically excited nitrogen atoms N(2D) are much more reactive and could play an important role in the formation of nitriles and other nitrogen bearing organic molecules in planetary atmospheres such as Titan. Despite this, few kinetic studies of N(2D) reactions have been performed over the appropriate low temperature range. Here, we report the results of an experimental study of the reactions N(2D) + methylacetylene, CH3CCH, and N(2D) + acetonitrile, CH3CN, using a supersonic flow reactor at selected temperatures between 50 K and 296 K. N(2D) atoms, which were generated indirectly as a product of the C(3P) + NO reaction, were subsequently detected by
laser induced fluorescence in the
vacuum ultraviolet wavelength region. The measured rate constants are significantly larger than the estimated values in current photochemical models and do not display large variations as a function of temperature. The new rate constants are included in a 1D coupled ion-neutral model of Titans atmosphere to test their influence on the simulated species abundances. In addition, the overall description of both reactions is improved by considering the results of recent experimental and theoretical work examining the product channels of these processes. These simulations indicate that while the N(2D) + CH3CCH reaction has only a limited overall influence on Titans atmospheric chemistry, the N(2D) + CH3CN reaction could lead to the formation of significant relative abundances of cyanomethamine, HNCHCN, in the upper atmosphere.
Read the full abstract ▾
All authors Kevin M. Hickson, Jean-Christophe Loison, Benjamin Benne, Michel Dobrijevic
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: End-to-End Performance Modeling of Optical System
Zhang Ban, Xiao-Bo Li, Xun Yang et al. (+11 more)
This study presents a comprehensive end-to-end simulation analysis of the optical imaging performance of the China Survey Space
Telescope (CSST) under in-orbit conditions. An integrated system model incorporating five static and two dynamic error sub-models was established. Wavefront errors were calculated for each sub-model and compared to the integrated system error to quantify the individual contributions to image degradation. At the detector level, wavefront error, point spread function (PSF), and ellipticity were evaluated across the full field of view (FOV). The average radius of 80% encircled energy (REE80) of the PSF under full-error conditions was determined for 25 field points, yielding a value of 0.114 arcseconds. Furthermore, the calculations indicate a correlation between the wavefront distribution and the ellipticity distribution within the optical system. By optimizing the wavefront distribution, it is possible to adjust the ellipticity distribution of the PSF across the full FOV. The end-to-end simulation approach adopted in this paper provides a theoretical foundation for improving the image quality in large-aperture, off-axis space
telescopes.
Read the full abstract ▾
All authors Zhang Ban, Xiao-Bo Li, Xun Yang, Yu-Xi Jiang, Hong-Cai Ma, Wei Wang, Jin-guang Lv, Cheng-Liang Wei, De-Zi Liu, Guo-Liang Li, Chao Liu, Nan Li, Ran Li, Peng Wei
Earth and Planetary Astrophysics
Observational evidence for a possible link between PAH emission and dust trap locations in protoplanetary disks
Nienke van der Marel, Niels F.W. Ligterink, Ryan van der Werf et al. (+4 more)
Polycyclic Aromatic Hydrocarbons (PAHs) are commonly detected in protoplanetary disks, but it is unclear what causes the wide range of intensities across the samples. In this work, the measured PAH intensities of a range of disks are compared with ALMA
dust continuum images, in order to test whether there is evidence that PAHs are frozen out on pebbles in
dust traps and only sublimate under certain conditions. A sample is constructed from 26 T Tauri and Herbig disks located within 300 pc, with constraints on the 3.3 $\mu$m PAH intensity and with high-resolution ALMA continuum data. The midplane temperature is derived using a power-law or with radiative transfer modeling. The warm
dust mass is computed by integrating the flux within the 30 K radius and convert to a
dust mass. A strong correlation with a Pearson coefficient of 0.88+/-0.07 between the 3.3 micron PAH intensity and the warm
dust mass was found. The correlation is driven by the combination of deep upper limits and strong detections corresponding to a range of warm
dust masses. Possible correlations with other disk properties like FUV radiation field or total
dust mass are much weaker. Correlations with PAH features at 6.2, 8.6 and 11.3 micron are potentially weaker, but this could be explained by the smaller sample for which these data were available. The correlation is consistent with the hypothesis that PAHs are generally frozen out on pebbles in disks, and are only revealed in the gas phase if those pebbles have drifted towards warm
dust traps inside the 30 K radius and vertically transported upwards to the disk atmosphere with sufficiently high temperature to sublimate PAHs into the gas phase. This is similar to previous findings on complex organic molecules in protoplanetary disks and provides further evidence that the chemical composition of the disk is governed by pebble transport.
Read the full abstract ▾
All authors Nienke van der Marel, Niels F.W. Ligterink, Ryan van der Werf, Milou Temmink, Paola Pinilla, Bin Jia, Quincy Bosschaart
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Multi-Channel Imager–The Cluster Field
Yushan Xie, Xiaokai Chen, Shuai Feng et al. (+20 more)
The Multi-Channel Imager (MCI), one of the instruments aboard the China Survey Space
Telescope (CSST), is designed to simultaneously observe the sky in three filters, covering wavelengths from the near-ultraviolet (NUV) to the near-infrared (NIR). With its large field of view ($7.5^{\prime}\times7.5^{\prime}$), MCI is particularly well-suited for observing
galaxy clusters, providing a powerful tool for investigating
galaxy evolution, dark matter and dark energy through gravitational
lensing. Here we present a comprehensive simulation framework of a strong
lensing cluster as observed by MCI, aiming to fully exploit its capabilities in capturing
lensing features. The framework simulates a strong
lensing cluster from the CosmoDC2 catalog, calculating the gravitational potential and performing ray-tracing to derive the true positions, shapes and light distribution of
galaxies within the cluster field. Additionally, the simulation incorporates intra-cluster light (ICL) and spectral energy distributions (SEDs), enabling further strong
lensing analyses, such as ICL seperation from
galaxy light and mass reconstruction combining strong and weak
lensing measurements. This framework provides a critical
benchmark for testing the MCI data pipeline and maximizing its potential in
galaxy cluster research.
Read the full abstract ▾
All authors Yushan Xie, Xiaokai Chen, Shuai Feng, Zhaojun Yan, Nan Li, Huanyuan Shan, Yin Li, Chengliang Wei, Weiwei Xu, Zhenya Zheng, Ran Li, Wei Chen, Zhenlei Chen, Chunyan Jiang, Dezi Liu, Lin Nie, Xiyan Peng, Lei Wang, Maochun Wu, Chun Xu, Fangting Yuan, Shen Zhang, Jing Zhong
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Integral Field Spectrograph–GEHONG: A Package for Generating Ideal Datacubes
Shuai Feng, Shiyin Shen, Wei Chen et al. (+17 more)
We developed a Python package GEHONG to mock the three-dimensional spectral data cube under the observation of an ideal
telescope for the Integral Field Spectrograph of the Chinese Space Station
Telescope (CSST-IFS). This package can generate one-dimensional spectra corresponding to local physical properties at specific positions according to a series of two-dimensional distributions of physical parameters of target sources. In this way, it can produce a spatially resolved spectral cube of the target source. Two-dimensional distributions of physical parameters, including surface brightness,
stellar population, and line-of-sight velocity, can be modeled using the parametric model or based on real observational data and numerical simulation data. For the generation of one-dimensional spectra, we have considered four types of spectra, including the
stellar continuum spectra, ionized gas emission lines, AGN spectra, and
stellar spectra. That makes GEHONG able to mock various types of targets, including
galaxies, AGNs,
star clusters, and HII regions.
Read the full abstract ▾
All authors Shuai Feng, Shiyin Shen, Wei Chen, Zhaojun Yan, Renhao Ye, Jianjun Chen, Xuejie Dai, Junqiang Ge, Lei Hao, Ran Li, Yu Liang, Lin Lin, Fengshan Liu, Jiafeng Lu, Zhengyi Shao, Maochun Wu, Yifei Xiong, Chun Xu, Yang Yang, Jun Yin
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Main Surveys-the Slitless Spectroscopy Simulation
Xin Zhang, Yue-dong Fang, Cheng-liang Wei et al. (+14 more)
The China Space Station
Telescope (CSST), slated to become China's largest space-based optical
telescope in the coming decade, is designed to conduct wide-field sky surveys with high spatial resolution. Among its key observational modes, slitless spectral observation allows simultaneous imaging and spectral data acquisition over a wide field of view, offering significant advantages for astrophysical studies. Currently, the CSST is in the development phase and lacks real observational data. As a result, the development of its data processing pipeline and scientific pre-research must rely on the mock data generated through simulations. This work focuses on developing a simulation framework for the CSST slitless spectral imaging system, analyzing its spectral dispersing properties and structural design. Additionally, the detection performance of the slitless spectral system is assessed for various astrophysical targets. Simulation results demonstrate that nearly all 1st order spectra are accompanied by corresponding 0th order images, facilitating accurate source identification. Furthermore, the GI spectral band exhibits superior detection efficiency compared to the GV and GU bands, establishing it as the primary observational band for
stellar and
galactic studies. This work successfully develops a simulation framework for the CSST slitless spectroscopic equipment.
Read the full abstract ▾
All authors Xin Zhang, Yue-dong Fang, Cheng-liang Wei, Guo-liang Li, Feng-shan Liu, Hang-xin Ji, Hao Tian, Nan Li, Xian-min Meng, Jian-jun Chen, Xia Wang, Rui Wang, Chao Liu, Zhong-wen Hu, Ran Li, Peng Wei, Jing Tang
High Energy Astrophysical Phenomena
A Census of Pulsars in Possible Association with Galactic Open Clusters
Lu Zhou, Zhi-Qiang You, Lu Li et al. (+3 more)
Among the $\sim 4000$ known
pulsars in our
Galaxy, $\lesssim 10\%$ are found in globular clusters, but none has been confirmed in any open clusters yet, although they outnumber globular clusters by about 20 times. In this work, we make use of the
Gaia DR3 catalog of
Galactic open clusters and conduct a
pulsar census, in order to identify
pulsars that are either 1) current members of open clusters, or 2) escaped from open clusters to the field. Among 164
pulsars with independent distance measurements and 3530 open clusters, we find that 4
pulsars are likely residing in open clusters. In particular, we find compelling evidence that the binary
pulsar J1302$-$6350 (B1259$-$63) is a member of the open cluster UBC~525; based on
Gaia data, we update its distance to be $2.26\pm 0.07$~kpc and measure the mass of its companion Be
star LS 2883 to be $16.8 M_\odot$. For 145
pulsars with both distance and proper motion measurements and 2967 open clusters with full kinematic parameters, we trace the past trajectories of both
pulsars and open clusters in the
Galactic gravitational potential, and find
pulsars that were within 3 times the radius of a cluster. This results in 19
pulsars that were likely born in open clusters. We discuss implications for the formation history of PSR J1302$-$6350 and highlight the scientific potential of searching for
pulsars in open clusters.
Read the full abstract ▾
All authors Lu Zhou, Zhi-Qiang You, Lu Li, Xiao-Jin Liu, Xing-Jiang Zhu, Zong-Hong Zhu
Astrophysics of Galaxies
APOGEE chemical abundances of stars in the MW satellites Fornax, Sextans, Draco and Carina
Cheng Xu, Yi Qiao, Baitian Tang et al. (+3 more)
During its
evolution, the Milky Way (MW) incorporated numerous
dwarf galaxies, particularly low-mass systems. The surviving
dwarf galaxies orbiting the MW serve as exceptional laboratories for studying the unique properties of these systems. Their metal-poor environments and shallow gravitational potentials likely drive significant differences in
star formation and
star cluster properties compared to those in the MW. Using high-quality near-infrared spectra from the APOGEE survey, we determined abundances of Fe, C, N, O, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, and Ce for 74
stars in four MW satellite
dwarf galaxies: Fornax, Sextans, Draco, and Carina. Our analysis reveals that the distribution of $\alpha$ elements (e.g., [Si/Fe]) strongly correlates with
galaxy luminosity (and hence mass), underscoring the critical role of
galaxy mass in shaping chemical
evolution. These
dwarf galaxies exhibit [Al/Fe$]\sim -0.5$, which is comparable to those of the metal-poor
stars in the MW. Additionally, we identified nitrogen-rich field
stars in the Fornax
dwarf galaxy, which display distinct
metallicities compared to its known globular clusters (GCs). If these
stars originated in GCs and subsequently escaped, their presence suggests we are observing relics of destroyed GCs, offering possible evidence of cluster disruption.
Read the full abstract ▾
All authors Cheng Xu, Yi Qiao, Baitian Tang, José G. Fernández-Trincado, Zhiqiang Yan, Doug Geisler
Solar and Stellar Astrophysics
A Study of Cataclysmic Variables from the eFEDS Survey
Rui Wang, Wei-Min Gu, Zhi-Xiang Zhang et al. (+3 more)
We present 17 cataclysmic variables (CVs) obtained from the crossmatch between the Sloan Digital Sky Survey (SDSS) and eROSITA Final Equatorial Depth Survey (eFEDS), including 8 known CVs before eFEDS and 9 identified from eFEDS. The photometric periods of four CVs are derived from the Zwicky Transient Facility (ZTF) and Catalina Real-Time Transient Survey (CRTS). We focus on two CVs, SDSS J084309.3$-$014858 and SDSS J093555.0+042916, and confirm that their photometric periods correspond to the orbital periods by fitting the radial velocity curves. Furthermore, by the combination of the
Gaia distance, the spectral energy distribution, and the variations of $\mathrm{H}\mathrm{\alpha}$ emission lines, the masses of the white
dwarf and the visible
star can be well constrained.
Read the full abstract ▾
All authors Rui Wang, Wei-Min Gu, Zhi-Xiang Zhang, Tuan Yi, Senyu Qi, Xiao-Jie Xu
Astrophysics of Galaxies
SDSS-ALMA Legacy Value Archival Gas Exploration (SALVAGE) – I: global star formation is governed by central (not global) molecular gas
Scott Wilkinson, Toby Brown, Chiara Circosta et al. (+3 more)
Star-forming
galaxies form tight relations between their
stellar mass,
star-formation rate, and molecular gas reservoir on global and resolved scales. On the path to quiescence, the exchange between gas and
stars must inevitably be broken. Understanding the mechanisms governing
star formation and quenching therefore requires observations of both the
stellar and molecular gas components. To this end, we have assembled a sample of 277
galaxies ($0.02 \lesssim z \lesssim 0.25$) with semi-resolved optical and millimetre $^{12}$CO(1-0) data, wherein the properties of the inner $\thicksim$2 kpc can be distinguished from the outer regions. This effort was made possible by the Sloan Digital Sky Survey (SDSS) catalogues and the maturing archive of the Atacama Large (sub-)Millimetre Array (ALMA). We call this
dataset the SDSS-ALMA Legacy Value Archival Gas Exploration (SALVAGE). In this work, we leverage SALVAGE to provide a semi-resolved perspective on global scaling relations and why some
galaxies deviate from them. In agreement with previous work, we find that the offset of a
galaxy from the global
star-forming main sequence (SFMS) is driven by its inner
star formation rate. With the relative inner and outer distributions of molecular gas fraction and
star formation efficiency, we investigate whether the central
star formation driving global changes is due to fuel availability or efficiency. We find that the position of a
galaxy within the SFMS is largely due to the inner
star-formation efficiency, while departure from the SFMS is driven by availability of central gas. The central few kpc are thus the most consequential region for
galaxy evolution at low
redshift.
Read the full abstract ▾
All authors Scott Wilkinson, Toby Brown, Chiara Circosta, Sara L. Ellison, Blake Ledger, Samuel D. Fielder
Earth and Planetary Astrophysics
The parametric oscillator model for the case of resonant argument circulations
Alexey Rosaev, Eva Plavalova and Pavel Nesterov
The goal of this paper is to obtain an approximate solution of the restricted three-body problem in the case of small perturbations in the vicinity of, but not in exact resonance. In this paper, we study the restricted threebody problem known as planetary type (i.e., when the eccentricity of the test particle is small). A method of linearizing the equation of motion close to (but not in) resonance is proposed under the assumption of small perturbations. In other words, we study orbits when the resonant argument circles the resonance. In the practically interesting case of resonant perturbations we can restrict our study to a perturbation with a single frequency with the largest amplitude, and reduce the problem to the Mathieu equation. The model qualitatively describes the behavior of the perturbation in the vicinity of the resonance. It can be used to estimate the exact position of the resonance and the boundaries between neighboring resonances.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Redshift-Frame Systematics and Their Impact on the Hubble Constant from Pantheon+ Supernovae
Said Laaroua
We present a full-sky, covariance-weighted analysis of
redshift-frame transformations in the Pantheon+ Type Ia
supernova sample to assess their impact on local measurements of the Hubble constant. Using 1,543
supernovae with heliocentric and CMB-frame
redshifts, we study the residual field delta z = zCMB - zHEL, which traces the
Solar System's kinematic correction. We recover the expected monopole <delta z> = (-3.8 +/- 0.1) x 10^-4 and a dipole amplitude A = (1.5 +/- 0.1) x 10^-3 aligned within 1 degree of the CMB dipole, confirming internal consistency. Propagating these residuals through the full Pantheon+ covariance
matrix yields a negligible shift in H0, at the <= 2% level of the current tension, placing a quantitative upper bound on
redshift-frame systematics.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Vacuum Polarization Effects in Baryon-Loaded Magnetar Bursts and Implications for X-ray Polarization
Tomoki Wada
Magnetars provide natural laboratories for strong-field
quantum electrodynamics processes, such as
vacuum polarization, which gives rise to
vacuum resonance together with the
plasma response. We develop a general framework to describe
vacuum resonance in a three-component
plasma consisting of ions, electrons, and positrons, as expected in
baryon-loaded magnetar bursts. By introducing a parametrization of the
plasma composition, we establish the general criterion for the occurrence of
vacuum resonance in such
plasmas. Our analysis encompasses both Mikheyev-Smirnov-Wolfenstein-like adiabatic mode conversion and nonadiabatic eigenmode transition, highlighting their dependence on the
plasma composition. Applying this framework to
baryon-loaded fireballs in magnetar bursts, we estimate the characteristic X-ray polarization signatures. Detection of these polarizations will provide observational signatures of
vacuum polarization as well as
baryon loading in magnetar fireballs.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Implication of multiple source populations of Galactic cosmic rays from proton and helium spectra
Qiang Yuan
Complicated hardenings and softenings of the spectra of
cosmic ray
protons and helium have been revealed by the newest measurements, which indicate the existence of multiple source populations of
Galactic cosmic rays. We study the physical implications of these results in this work. A phenomenological fitting shows that three components can properly give the measured structures of the
proton and helium spectra. The data are then accounted for in a physically motivated, spatially-dependent propagation model. It has been shown that one background source population plus two local sources, or two background source populations plus one local source can well reproduce the measurements. The spectral structures of individual species of
cosmic rays are thus natural imprints of different source components of
cosmic rays. Combined with ultra-high-energy $\gamma$-ray observations of various types of sources, the mystery about the origin of
Galactic cosmic rays may be uncovered in future.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Improving pulsar search efficiency in next-generation pulsar surveys with artificial intelligence
Qiuyang Fu, Mengyao Xue, Weiwei Zhu et al. (+12 more)
Pulsar searching with next-generation
radio telescopes requires efficiently sifting through millions of candidates generated by search pipelines to identify the most promising ones. This challenge has motivated the utilization of Artificial Intelligence (AI)-based tools. In this work, we explore an optimized
pulsar search pipeline that utilizes deep learning to sift “snapshot” candidates generated by folding de-dispersed time series data. This approach significantly accelerates the search process by reducing the time spent on the folding step. We also developed a script to generate simulated
pulsars for benchmarking and model fine-tuning. The
benchmark analysis used the NGC 5904 globular cluster data and simulated
pulsar data, showing that our pipeline reduces candidate folding time by a factor of $\sim$10 and achieves 100% recall by recovering all known detectable
pulsars in the restricted parameter space. We also tested the speed-up using data of known
pulsars from a single observation in the Southern-sky MWA Rapid Two-metre (SMART) survey, achieving a conservatively estimated speed-up factor of 60 in the folding step over a large parameter space. We tested the model's ability to classify
pulsar candidates using real data collected from the FAST, GBT, MWA, Arecibo, and Parkes, demonstrating that our method can be generalized to different
telescopes. The results show that the optimized pipeline identifies
pulsars with an accuracy of 0.983 and a recall of 0.9844 on the real
dataset. This approach can be used to improve the processing efficiency for the SMART and is also relevant for future SKA
pulsar surveys.
Read the full abstract ▾
All authors Qiuyang Fu, Mengyao Xue, Weiwei Zhu, N. D. R. Bhat, Kaichao Wu, Zihan Zhang, B. W. Meyers, Chia Min Tan, Youling Yue, Jiarui Niu, Lingqi Meng, Ziwei Wu, Ziyao Fang, Yukai Zhou, Jiawei Jin
High Energy Astrophysical Phenomena
Seyfert Galaxies as Neutrino Sources: An Outflow$-$Cloud Interaction Perspective
Zhi-Peng Ma, Kai Wang, Yuan-Yuan Zuo et al. (+1 more)
Following the identification of the first confirmed individual
neutrino source, Seyfert
galaxies have emerged as the most prominent class of high-energy
neutrino emitters. In this work, we perform a detailed investigation of the
outflow–cloud interaction scenario for
neutrino production in Seyfert
nuclei. In this framework, fast AGN-driven winds collide with clumpy gas clouds in the
nuclear region, forming bow shocks that efficiently accelerate
cosmic-ray
protons. The accelerated
protons subsequently interact with cold
protons from the
outflows via inelastic
proton–
proton ($pp$) collisions, producing high-energy
neutrinos, while the photomeson ($p\gamma$) process with disk
photons may provide a subdominant contribution at the highest energies. Applying this model to five
neutrino-associated Seyfert
galaxies, we successfully reproduce the observed TeV
neutrino fluxes without violating existing gamma-ray constraints. By integrating over the Seyfert population using X-ray luminosity functions, we further demonstrate that Seyfert
galaxies can account for a substantial fraction of the diffuse astrophysical
neutrino background in the $10^4-10^5~{\rm GeV}$ energy range.
Read the full abstract ▾
All authors Zhi-Peng Ma, Kai Wang, Yuan-Yuan Zuo, Yuan-Chuan Zou
Solar and Stellar Astrophysics
Relevance of Murchison Widefield Array Interplanetary Scintillation Observations to Heliospheric Transient Catalogues
A. Waszewski, J.S. Morgan, M.C.M. Cheung et al. (+6 more)
We have conducted a comprehensive comparison of interplanetary scintillation (IPS) observations taken by the Murchison Widefield Array (MWA) with several heliospheric transient event catalogues, over a time period of 7 months during
solar minimum. From this analysis we have found that of the 84% of catalogued events that have MWA IPS data available, 68% of them appear in MWA observations. Of the enhancements first identified in IPS observations, only 58% have a potential match with a catalogued event. The majority of enhancements that were identified in the IPS observations were situated greater than 10$^\circ$ from the ecliptic plane. Two such features were selected for detailed analysis, connecting their
solar origins to their propagation through the heliosphere. The first of these features was created by a coronal mass ejection (CME), captured over two successive MWA observations and recorded in several catalogues. The second feature has the potential of being a stream interaction region (SIR) travelling out of the ecliptic plane. This particular SIR was not recorded in any catalogue. Thus the MWA shows promise in detecting heliospheric transients that other commonly-used techniques may overlook. These results show the strength of the MWA in having unbridled access to the heliosphere, able to make remote observations of events far out of the ecliptic as it is not restrained to the orbits of spacecraft. We demonstrate how the inclusion of MWA IPS data can potentially boost the number of CME and SIR events that are characterised.
Read the full abstract ▾
All authors A. Waszewski, J.S. Morgan, M.C.M. Cheung, R. Ekers, E. Samara, S. Majumdar, R. Chhetri, N.D.R. Bhat, M. Johnston-Hollitt
Solar and Stellar Astrophysics · Cross-listed from physics.plasm-ph
The Non-thermal Energy Window for Laser-Driven Nuclear Reactions
Eunseok Hwang, Heamin Ko, Myung-Ki Cheoun et al. (+1 more)
Laser-driven
nuclear reactions proceed in non-
equilibrium plasma conditions, producing ion energy distributions that are not Maxwellian. Nevertheless, fusion yields in such experiments are often interpreted using effective thermal descriptions based on the conventional Gamow window. In this work, we develop an analytical framework for evaluating
nuclear reaction rates for non-thermal ions accelerated by the Target Normal Sheath Acceleration (TNSA) mechanism. Using a self-similar
plasma expansion model, we derive a closed form expression for an effective reaction energy window and the corresponding fusion reactivity. The resulting effective energies differ systematically from those predicted by thermal models, indicating limitations of interpretations based on the conventional Gamow window in
laser-driven environments. This framework provides a quantitative basis for analyzing fusion yields and for designing
laser-driven
nuclear experiments.
Read the full abstract ▾
All authors Eunseok Hwang, Heamin Ko, Myung-Ki Cheoun, Dukjae Jang
Instrumentation and Methods for Astrophysics
SVOM Follow-up Observation Coordinating Service
Xu-hui Han, Pin-pin Zhang, Yu-jie Xiao et al. (+27 more)
The Sino-French SVOM (Space Variable Objects Monitor) mission is a space-based astronomy mission complemented with ground-based dedicated instrumentation. It aims to explore and study high-energy
cosmic phenomena, such as gamma-ray bursts (GRBs). This unprecedented combination of space-based and ground-based instruments will provide leading multi-wavelength observational capabilities in gamma-rays, X-rays, optical, and near-infrared bands. The complete observation sequence of each GRB triggered by the SVOM mission consists of three stages, the GRB detections, followed by the on-board and grounded automatic follow-ups, and rapid deep multi-band photometry and spectroscopy re-visit observations. To efficiently organize all grounded instruments performing automatic follow-ups and re-visit observations, we develop a follow-up observation coordinating service (FOCS), which is capable of performing GRB trigger distributing, automatic observation scheduling and observation coordination supporting by providing a user support platform. The FOCS also facilitates the provision of observational planning for ground-based
telescopes to conduct synchronized observations of identical celestial regions as SVOM. The FOCS is utilized for the SVOM-dedicated ground-based
telescopes as well as for associated partner
telescopes. Since the launch of SVOM in June 2024, as the FOCS system joining the operations of SVOM, multiple successful observations have been made for SVOM GRBs. In this paper, we present the goals of the FOCS system as well as the principle and workflow developed to achieve these goals. The structure, technical design, implementation, and performance of the FOCS system are also described in detail. We conclude with a summary of the current status of the FOCS system and our near-future development plan.
Read the full abstract ▾
All authors Xu-hui Han, Pin-pin Zhang, Yu-jie Xiao, Ruo-song Zhang, Chao Wu, Li-ping Xin, Hong-bo Cai, Hai Cao, Hui-jun Chen, Jin-song Deng, Wen-long Dong, Guo-wang Du, Lei Huang, Lin Lan, Hua-li Li, Guang-wei Li, Xiao-meng Lu, Yu-lei Qiu, Jian-feng Tian, Jing Wang, Wen-jin Xie, Da-wei Xu, Yang Xu, Zhu-heng Yao, Xue-ying Zhao, Jie Zheng, Wei-kang Zheng, Ya-tong Zheng, Xiao-xiao Zhou, Jian-yan Wei