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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 30 July

High Energy Astrophysical Phenomena

Thermal or Non-thermal? Diffuse emission in the infall region of stacked galaxy groups

E. Bulbul, X. Zhang, Z. Ding et al. (+16 more)

The faint infall regions surrounding the virial radius of galaxy groups remain largely unexplored due to their low X-ray surface brightness. Using the large statistical power of SRG/eROSITA survey observations, we present the first spectroscopic measurement of the intragroup medium (IGrM) in the infall regions of a large sample of low-mass galaxy groups ($M_{\rm tot}<1\times10^{14}\,M_{sun}$), extending to $\sim2\,R_{200m}$ (2.2 Mpc). Through spectral stacking of 827 nearby groups from the first eROSITA All-Sky Survey catalog, we detect diffuse emission and measure the thermodynamic properties of gas at densities previously inaccessible to X-ray observations. The stacked spectra are well described by a Gaussian differential emission measure model, yielding a temperature distribution with a mean temperature of $0.96_{-0.04}^{+0.05}$ keV and width of $0.28_{-0.10}^{+0.10}$ keV, and a metal abundance of $0.21_{-0.04}^{+0.06}$ A$_{sun}$, consistent with expectations for group outskirts. The inferred electron densities decrease from $(4.8\pm1.3)\times10^{-5}$cm$^{-3}$ at $(0.7-2)\,R_{500c}$ to $(5.5\pm2.0)\times10^{-6}$ cm$^{-3}$ at $(2-4)\,R_{500c}$, demonstrating eROSITA's ability to probe the low-density outskirts of galaxy groups. Residual emission in the spectra suggests the presence of an additional spectral component. While a secondary thermal interpretation requires an unexpectedly hot, metal-poor plasma, a non-thermal inverse Compton model provides an equally plausible explanation, contributing $\sim30\%$ of the thermal flux. Assuming that the additional component is produced by inverse Compton emission from a common population of relativistic electrons, the inferred magnetic field strength would be in the sub-$\mu$G regime.
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All authors E. Bulbul, X. Zhang, Z. Ding, T. Mistele, M. Kluge, E. Artis, Y. E. Bahar, K. Dennerl, D. Eckert, L. Fiorino, P. F. Hopkins, N. Malavasi, A. Merloni, K. Nandra, E. Quataert, M. E. Ramos-Ceja, J. S. Sanders, J. Strunk, S. Zelmer

High Energy Astrophysical Phenomena

The SRG/eROSITA All-Sky Survey DR2: Cumulative X-ray catalogues from the first three surveys and multi-wavelength counterparts in the western Galactic hemisphere

M. E. Ramos-Ceja, G. Lamer, M. Salvato et al. (+111 more)

The eROSITA telescope array on board the Spektrum-Roentgen-Gamma (SRG) mission began its all-sky survey program in December 2019, scanning the sky at an approximately six-month cadence. Here, we present new catalogues of point-like and extended X-ray sources derived from the first three completed eROSITA all-sky surveys (eRASS:3), covering the western Galactic hemisphere, which Germany's eROSITA consortium holds proprietary rights for. We describe the observational strategy, data processing, and analysis pipelines. We also characterise the resulting X-ray source populations. The eRASS:3 main catalogue contains nearly two million sources, including 1,911,744 point-like and 63,796 extended sources, detected in the 0.2-2.3 keV energy band, eROSITA's most sensitive energy window. This volume has doubled the X-ray source content of eRASS1 and provides a comprehensive census of X-ray-emitting objects across diverse astrophysical classes. We also released a secondary hard catalogue of nearly 15,000 sources detected in the harder 2.3-5.0 keV energy band. In addition, we released six catalogues, three for the main sample and three for the hard sample, in which we identify and classify the optical and infrared counterparts of eRASS:3 point-like sources. This approach delivers a homogeneous, high-quality identification of mostly extragalactic X-ray emitters; for example, we estimate that approximately 88% of the 1.4 million counterparts identified within the footprints of the Legacy Survey Imaging for DESI are extragalactic sources. This work has enabled the generation of samples optimised for completeness and purity, while expanding the discovery space for rare populations. The second data release (DR2) of the SRG/eROSITA all-sky survey is a catalogue-only release, comprising the catalogues presented in this work together with an updated version of the eROSITA upper flux limit server.
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All authors M. E. Ramos-Ceja, G. Lamer, M. Salvato, A. Merloni, J. S. Sanders, A. Georgakakis, T. Liu, E. Bulbul, J. Buchner, K. Dennerl, M. J. Freyberg, S. Friedrich, I. Kreykenbohm, C. Maitra, K. Nandra, P. Predehl, T. H. Reiprich, J. Robrade, A. Schwope, R. Shirley, B. Stelzer, I. Stewart, R. Seppi, H. Starck, D. Tubin-Arenas, I. Traulsen, E. Artis, C. Aydar, P. Baldini, F. Balzer, W. Becker, M. M. Bennedik, W. Bornemann, M. Brueggen, J. Brink, M. Brusa, V. Burwitz, M. Canal i Saguer, N. Clerc, J. Comparat, M. Coriat, J. V. Correa-Rodrigues, S. Czesla, L. Dauner, J. Dietl, Z. Ding, L. Ducci, T. Dwelly, L. Fiorino, S. Freund, P. Friedrich, R. Gaida, E. Gatuzz, S. T. Guida, S. Haemmerich, F. Haberl, G. Hartner, S. Hernandez-Diaz, Z. Igo, N. Ilic, D. M. Kaltenbrunner, A. Khokhriakova, W. Kink, C. Kirsch, M. Kluge, S. Krippendorf, M. Krumpe, S. Kulkarni, J. Kurpas, E. Kyritsis, R. Laktionov, A. Liu, M. Lorenz, N. Malavasi, M. G. F. Mayer, N. Meidinger, T. Mistele, S. Mueller, D. Muñoz-Giraldo, N. T. Nguyen-Dang, Q. Ni, S. Ok, N. Ota, G. Puehlhofer, F. Pacaud, A. Pandya, E. Perinati, C. Pommranz, G. Ponti, K. Poppenhaeger, K. G. Pradeep, A. Rau, W. Roster, S. Rukdee, S. Saeedi, A. Santangelo, M. Sasaki, S. Sheth, S. Shreeram, M. Sommer, A. Srivastava, V. Suleimanov, J. Truemper, N. Vasilas, A. Veronica, N. Webb, P. Weber, J. Wilms, M. C. H. Yeung, F. Zangrandi, S. Zelmer, X. Zhang, Y. Zhang, X. Zheng

Earth and Planetary Astrophysics

Accretion Burst Crystallizes Silicates in a Planet-Forming Disk

Jeong-Eun Lee, Chul-Hwan Kim, Jaeyeong Kim et al. (+13 more)

Crystalline silicates form at high temperatures (> 900 K; Fabian et al. 2000; Hallenbeck et al. 1998). Their presence in comets (Hanner et al. 1994; Hayward et al. 2000; Wooden et al. 2002; Shinnaka et al. 2018) suggests that high-temperature dust processing occurred in the early Solar System and was subsequently transported outward to comet-forming regions. However, direct evidence for this crystallization and redistribution in Sun-like protostars has remained elusive. By comparing James Webb Space Telescope (JWST) mid-infrared spectra of the periodically bursting protostar EC 53 (Lee et al. 2020), we detect crystalline silicate (forsterite and enstatite) emission features that appear only during the burst. The emergence of these features indicates active crystal formation via thermal annealing in the hot inner disk during the accretion burst. We also detect a nested outflow-a collimated atomic jet enclosed by slower molecular outflows, consistent with magnetohydrodynamic (MHD) wind models (Pascucci et al. 2025). This configuration provides a mechanism for outward transport of freshly crystallized silicates (Giacalone et al. 2019). Our results provide the first direct observational evidence of in-situ silicate crystallization during episodic accretion bursts in a very young star still embedded in its dense envelope. Although we do not directly detect grains transported to the outer disk, the observed trends are consistent with outward redistribution, indicating that both dust processing and transport occur during the earliest and most dynamic stages of star formation.
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All authors Jeong-Eun Lee, Chul-Hwan Kim, Jaeyeong Kim, Seokho Lee, Young-Jun Kim, Seonjae Lee, Giseon Baek, Joel D. Green, Gregory J. Herczeg, Doug Johnstone, Klaus M. Pontoppidan, Yuri Aikawa, Yao-Lun Yang, Logan Francis, Mihwa Jin, Hyerin Jang

Earth and Planetary Astrophysics

The International Lunar Reference System

Agnès Fienga

As the exploration of the Moon accelerates in the coming years, there is already an urgent need to standardise the Position, Navigation and Timing of spacecraft, and consequently for the definition of the lunar reference system and frame. This document gathers the most recent recommendations of the the International Association of Geodesy (IAG) / International Astronomical Union (IAU) Joint Working Group (WG) 1.1.3 "Lunar Reference frames" on the topic. Despite the challenges for producing a Lunar Reference System and Frame due to the limited number of control points and a single data type, the WG proposes applying an approach developed for Global Navigation Satellite Systems (GNSS). This supports an accurate and reliable reference system, consistent with International Earth Rotation and Reference Systems Service (IERS) standards and, based on redundant sources, ensures resilience for the lunar Position, Navigation and Timing (PNT) framework. The first realization of the International Lunar Reference Frame 2026 (ILuRF2026), ILuRF2026, is delivered on the temporay website https://ilurs-6e772d.gitlab.io/ and on the future http://ilurf.gssc.esa.int together with associated software.
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Solar and Stellar Astrophysics

Long-term high-resolution spectroscopic monitoring of the evolved metal-poor binary PS Gem

V.G. Klochkova, V.E. Panchuk, J.K. Zhao et al. (+3 more)

We present results of long-term high-resolution spectroscopic monitoring of the extremely low-metallicity star PS Gem (=HD 52961), associated with IRAS 07008+1050. The spectra were obtained with the 6-meter BTA telescope at a resolving power of R=60000 during 1997–2025, providing a homogeneous dataset spanning nearly three decades. Quantitative measurements of the H$\alpha$ two-peaked profile reveal repeatable phase-dependent variations of the peak-intensity ratio $I_{\rm V}/I_{\rm R}$ and the absorption-core velocity over multiple orbital cycles, whereas the peak separation remains nearly constant at $\Delta V_r = 78\pm 4$ km s$^{-1}$. The heliocentric radial velocity measurements yield a systemic velocity of $\gamma=7.46\pm 0.64$ km s$^{-1}$ and an orbital semi-amplitude of $K=2.49$ km s$^{-1}$. No significant long-term secular drift is observed over the monitoring interval. The stellar luminosity, estimated from the equivalent width of the OI 7773 Ȧ triplet ($W_{\lambda}=1.16\pm$ 0.02 Ȧ), corresponds to $\log(L/L_{\odot})\approx$3.5. The average radial velocity of diffuse interstellar bands is consistent with the location of PS Gem in the Local Arm. These observations provide rare multi-decade time-domain constraints on the dynamical behavior of this evolved metal-poor star.
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All authors V.G. Klochkova, V.E. Panchuk, J.K. Zhao, Y.Q. Wu, N.S. Tavolzhanskaya, G. Zhao

High Energy Astrophysical Phenomena

Comprehensive X-ray Study of Giant Radio Galaxies with XMM-Newton and Chandra

Niraj Maurya, Satish S. Sonkamble, Suraj Dhiwar et al. (+3 more)

We present a systematic X-ray spectral analysis of 27 giant radio galaxies (GRGs) using archival XMM-Newton and Chandra data. Roughly 44% of the sample show intrinsic absorption ($N_{\mathrm{H,int}} \gtrsim 10^{21}\,\mathrm{cm}^{-2}$), while several exhibit narrow Fe K$\alpha$ emission lines with equivalent widths up to $\sim$570 eV. Soft X-ray features are also common, including thermal plasma emission (kT$\sim 0.2$–0.8 keV) and ionized absorbers, in some cases consistent with high-velocity outflows. The photon indices are typically hard (median $ \Gamma \sim 1.6$), in line with radio-loud AGN. A comparison between nuclear X-ray luminosity and extended radio power shows that many sources host relatively strong X-ray cores compared to their lobes, pointing toward possible restarted nuclear activity. For 10 GRGs with published black hole masses, we explore preliminary relations with X-ray luminosity, Eddington ratio, and photon index. We find a positive trend between $M_{\rm BH}$ and $L_{2-10\,{\rm keV}}$, while Eddington ratios show no clear dependence on mass. A tentative negative relation between $\lambda_{\rm Edd}$ and $\Gamma$ hints at inefficient accretion, although confirmation will require larger samples. Overall, GRGs display diverse nuclear conditions and accretion states, supporting scenarios where obscuration, episodic or restarted activity, and low-efficiency accretion shape their long-term evolution.
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All authors Niraj Maurya, Satish S. Sonkamble, Suraj Dhiwar, M. B. Pandge, S. Ilani Loubser, Avinash Kale

Instrumentation and Methods for Astrophysics

PhySR: Physics-Informed Neural Network for Super-Resolution Reconstruction in Radio Synthesis Imaging

Hongkun Yang, Li Zhang, Ming Zhang et al. (+1 more)

Radio telescope arrays are constrained by the number of antennas and baseline distribution, resulting in incomplete spatial-frequency sampling, limited image resolution, and blurring, distortion, and loss of small-scale structures caused by coupling between the primary and synthesized beams. Existing general-purpose model-driven methods remove observational effects sequentially and may accumulate errors, but cannot directly address limited imaging resolution, while data-driven methods lack explicit physical constraints. We propose PhySR, an end-to-end physics-informed neural network that combines a U-Net backbone, dynamic cascaded upsampling, a multiscale feature residual module, and a differentiable physical forward model incorporating the primary beam response, PSF convolution, and scale mapping. PhySR directly reconstructs high-resolution images from low-resolution dirty images without high-resolution labels while maintaining observation-domain consistency. Experiments on simulated SKA-Mid data show that, for 4x super-resolution, PhySR achieves a PSNR of 44.65 dB, an SSIM of 0.9940, and an RMSE of 0.0065. Compared with existing general-purpose methods, PSNR and SSIM improve by approximately 13.23 dB and 0.3760, respectively. Compared with mainstream deep learning models, PSNR and SSIM improve by 6.50 dB and 0.0682, while RMSE decreases by 0.0069. PhySR also remains stable for 2x and 8x super-resolution and achieves low observation-domain consistency errors, demonstrating advantages in coupling-effect removal, small-scale structure recovery, and physical consistency.
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All authors Hongkun Yang, Li Zhang, Ming Zhang, Yong-Feng Huang

High Energy Astrophysical Phenomena

eRASSU J043115.8-711730 :the first pulsating symbiotic super-soft X-ray source in the Magellanic Bridge

Tathagata Saha, Chandreyee Maitra, Philip Charles et al. (+9 more)

The Magellanic Bridge stellar population is a relic of the tidal interaction between the Large and Small Magellanic Clouds. A comprehensive view of the evolution of the Bridge stellar population requires probing the compact remnants of stellar evolution, otherwise hidden at optical wavelengths. The all-sky survey conducted by the eROSITA instrument on-board the Spectrum Roentgen Gamma observatory has discovered a significant population of compact-object-powered systems in the Bridge using X-ray. The candidate super-soft source eRASSU J043115.8-711730 (hereafter J0431-71) was discovered as a part of this campaign, and we present here a deeper study of this source using XMM-Newton and SALT spectroscopy, long-term optical-infrared photometry using OGLE, ATLAS, ASAS-SN, WISE, and GAIA data. J0431-71 is a highly variable super-soft X-ray source, classified as a red giant with the GAIA color-magnitude diagram. The source exhibits: (a) a thermal X-ray spectrum with a temperature of kT$\sim$30 eV and a bright state luminosity of $3.2\times10^{37}$~erg~s$^{-1}$ in the 0.15-1 keV band, (b) Balmer emission lines, [Fe X] coronal line, HeII emission, and the Bowen fluorescence blend, (c) an optical and infrared periodicity of $\sim$500-560 days in phase with the X-ray-UV emission, (d) a 'redder-when-brighter' trend in the stellar emission with a $\sim$520 day period indicating a pulsating donor star. We argue that the observed spectral and temporal properties in J0431-71 are consistent with a high-accretion rate onto a white-dwarf via Roche-lobe overflow, making J0431-71 the first symbiotic source discovered in the Bridge.
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All authors Tathagata Saha, Chandreyee Maitra, Philip Charles, Frank Haberl, David Kaltenbrunner, Andrzej Udalski, David Buckley, Itumeleng Monageng, Lee Townsend, Manami Sasaki, Sara Saeedi, Mara Salvato

High Energy Astrophysical Phenomena

Distinct Jet Properties in the X-Ray-Obscured State of GRS 1915+105

Xi Yan, Lang Cui, Sergei Trushkin et al. (+6 more)

GRS 1915+105 has remained in an X-ray-obscured state since its transition from a long-lasting unobscured state in 2019. We report on 6.7-GHz East Asia VLBI Network observations of GRS 1915+105 obtained during strong radio flares detected at 2.3–11.2 GHz with the RATAN-600 radio telescope in 2025. Our images reveal two contrasting jet morphologies. The first epoch, associated with a flare evolving from an optically thick to an optically thin spectrum, shows a bright radio core accompanied by an extended jet structure. By contrast, the second epoch, observed near the peak of another flare displaying optically thin emission at lower frequencies, is dominated by two bright, symmetric, well-separated jet blobs and shows no detectable radio core. If these jets exhibited the apparent superluminal motions commonly observed prior to 2019, measurable angular shifts would be expected over the five-hour observations. However, no significant jet motion is detected. Combined with our derived jet speed of $\beta\Gamma \lesssim 0.40$, these results suggest that the jets launched during the current obscured state are slower than the relativistic jets ($\beta\Gamma \gtrsim 1$) observed earlier during the unobscured state. Together with the recently reported large variations in jet orientation, our findings in GRS 1915+105 provide robust support for the emerging paradigm that X-ray binary jets launched in obscured and unobscured states likely exhibit distinct propagation properties.
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All authors Xi Yan, Lang Cui, Sergei Trushkin, Shuangjing Xu, Wu Jiang, Zhen Yan, Sándor Frey, Timur Mufakharov, Ruchika Dhaka

Astrophysics of Galaxies

The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDS

P. Arévalo, J. Buchner, M. Salvato et al. (+10 more)

(abridged) Aims: To characterize variability-selected AGN candidates within the eROSITA Final Equatorial-Depth Survey (eFEDS), leveraging the synergy between optical variability and deep X-ray observations by SRG (Spectrum Roentgen Gamma)/eROSITA, to compare the physical properties of AGN populations selected through complementary methods. Methods: We used a sample of AGN candidates selected via optical variability by Arévalo et al. and cross-match it to the X-ray selected eFEDS AGN sample. Spectroscopic characterizations are obtained for the matched samples from the Dark Energy Spectroscopic Instrument public data products. Results: We find a high classification purity with 98% candidates confirmed as broad-line AGN/QSOs. We identify a significant population (25%) that lack X-ray counterparts (X-U) in the eFEDS survey. We find that the X-D and X-U samples exhibit distinct physical properties and redshift distributions. The X-U sample peaks at $z = 2$ while the X-D sample at $z =1$, with nearly half of the variability-selected AGN at $z > 2.5$ remaining undetected in X-rays. This missing fraction can be attributed to K-correction effects and SED evolution with luminosity, mainly resulting in high accretion rate objects falling out of the X-D sample at higher redshifts. X-ray variability accounts for a part of the missing fraction but its dependence with redshift is less clear. Ensemble spectral analysis reveals that X-D sources have steeper optical continua and stronger broad emission lines than their X-U counterparts, while the forbidden and semi-forbidden lines have equal EWs in both samples. Finally, broad absorption line (BAL) features are found almost exclusively in the X-U population. This "missing" X-ray population must be accounted for when extrapolating X-ray-selected AGN to the broader Type I population and could impact cosmic estimates of massive black hole growth.
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All authors P. Arévalo, J. Buchner, M. Salvato, P. Sánchez-Sáez, F. Bauer, M.L. Martínez-Aldama, D. Tubín-Arenas, J. Cerón-Meneses, R. Pucha, P. Lira, A. Merloni, M. Mezcua, M. Krumpe

Instrumentation and Methods for Astrophysics

Proof of Concept Measurements of Laterally Graded Multilayers for Soft X-ray Spectropolarimetry

Sarah Heine, Herman L. Marshall, Alan Garner et al. (+2 more)

This work describes proof of concept measurements for a soft X-ray spectropolarimeter that utilizes laterally graded multilayer mirrors within a grating spectrometer. The work tests two multilayers: a Chromium-Scandium multilayer designed to be utilized at Brewster's angle in the 200-400 eV range and a Tungsten Boron Carbide mirror designed to reflect X-rays at 30 degrees incidence in the 500-850 eV range. We present measurements of monochromatic, polarized light reflecting off of these multilayers over a range of polarization angles, demonstrating the expected modulation of signal with respect to incident polarization angle
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All authors Sarah Heine, Herman L. Marshall, Alan Garner, Eric Gulllikson, Nithya Kothnur

Astrophysics of Galaxies

Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae

Yunning Zhao, Wei Zhang, Lin Ma et al. (+10 more)

Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and WISE Galactic HII region catalog, we construct a sample of 280 Galactic HII regions and candidates in the Outer Galaxy (80$^{\circ}$ $\lesssim$ l $\lesssim$ 220$^{\circ}$). Using MRS-N optical spectra, we measure four emission lines (H$\alpha$, [NII]$\lambda$6584, [SII]$\lambda\lambda$6717,6731) and use line-ratios to spectroscopically confirm 255 HII regions, including 90 previously "Known" HII regions and 165 newly classified ones. We measure their $T_{\rm e}$, $n_{\rm e}$ and oxygen abundance, and determine distances via associated OB stars and the kinematic method. The sample spans $R_{\rm gal}$ from 8.16 to 15.36 kpc, enabling investigation of radial gradients in physical properties. We find [NII]/H$\alpha$ and [SII]/H$\alpha$ decrease with increasing $R_{\rm gal}$, while [SII]/[NII] remains nearly flat; these trends are quite different from diffuse ionized gas (DIG). We derive the $T_{\rm e}$ gradient of 344.530 $\pm$ 78.083 K kpc$^{-1}$, and the $\log n_{\rm e}$ gradient of -0.143 $\pm$ 0.041 cm$^{-3}$ kpc$^{-1}$. Oxygen abundance shows a steep slope of -0.044 $\pm$ 0.010 dex kpc$^{-1}$ in the inner disk and a shallow slope of -0.016 $\pm$ 0.005 dex kpc$^{-1}$ in the outer disk, with a global slope of -0.014 $\pm$ 0.005 dex kpc$^{-1}$. We also examine the two-dimensional distributions of $T_{\rm e}$, $n_{\rm e}$, and oxygen abundance, and find the gradients vary with azimuth. There is no obvious difference between spiral arm and interarm regions, and no trend appears along individual arms. From [NII]/H$\alpha$-[SII]$\lambda$6717/H$\alpha$ diagram, HII regions have a S$^+$/S ratio (0.32), lower than DIG (0.43); however, heavy overlap prevents clear separation from this diagram alone.
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All authors Yunning Zhao, Wei Zhang, Lin Ma, Shiming Wen, Tao Jing, Cheng Li, Zheng Zheng, Aiyuan Yang, Shichao Han, Juanjuan Ren, Jianjun Chen, Hong Wu, Yongheng Zhao

High Energy Astrophysical Phenomena

On the Blueprint of Active Galaxies Producing Neutrinos

Chen Li and Francis Halzen

Based on the observation of the active galaxies NGC 1068 and TXS 0506+056, and on additional evidence for the sources NGC 4151, CGCG 420-015, NGC 7469, and the Circinus Galaxy emerging from IceCube data, we make the case for the production of high-energy neutrinos within a few gravitational radii of supermassive black holes surrounded by a dense plasma radiating X-rays. X-rays represents the target for the production of neutrinos by protons accelerated near the black hole; they also absorb the gamma rays from the decay of neutral pions produced in the same interactions. Neutrinos with energies of tens of TeV and above originate in photoproduction interactions with X-rays of $0.1 \sim 1$\,keV energy on the $\Delta$ resonance, $p + \gamma \rightarrow \Delta \rightarrow n + \pi^+$. Our analysis of the multimessenger data points to gamma-ray-obscured sources with a characteristic neutrino flux linearly proportional to the X-ray flux originating within $\sim 10$ gravitational radii of the black holes, with lower values preferred. We speculate on such sources producing the diffuse flux of neutrinos and cosmic rays of extragalactic origin.
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High Energy Astrophysical Phenomena

An extra hard spectral component peaking at sub-GeV in the prompt emission of GRB 260226A

Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu et al. (+1 more)

The prompt emission spectra of gamma-ray bursts (GRBs) have long been empirically described by the Band function over the keV–MeV range, whereas several Fermi/LAT-detected GRBs show evidence for an extra hard component at higher energies. Here we present a joint GBM–LAT study of GRB~260226A, a rare LAT seeded onboard trigger GRB, and find that an extra sub-GeV component is present. In the time-resolved analysis, we find that a cutoff power-law model fits the spectral data of the extra component better than other models at earlier times, while at later times, the broken power-law model is preferred (or at least equally good). Interpreting the early cutoff as the $\gamma\gamma$ absorption implies that the Lorentz factor at early time is lower and increases with time. The low ratio between the peak energy of the extra component and that of the Band component is difficult to explain with a one-zone synchrotron self-Compton (SSC) scenario. Two-zone emission models, such as external inverse Compton scattering of the photosphere emission by relativistic electrons accelerated in internal shocks, could provide a possible explanation.
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All authors Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu, Xiang-Yu Wang

Instrumentation and Methods for Astrophysics

Design and testing progress towards the first flight of the rocket experiment demonstration of a Soft X-ray Polarimeter (REDSoX)

Sarah N.T. Heine, Herman L. Marshall, Alan Garner et al. (+11 more)

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA-funded, sounding rocket mission. The rocket payload will measure polarization strength and direction as a function of energy in the 0.2-0.4 keV band, providing complementary measurements to those made by IXPE in the 2-8 keV band. The first flight, scheduled for 2028, will provide a technology demonstration of our polarimeter concept, which utilizes an aligned system of a focusing optic, Critical-Angle Transmission (CAT) gratings, Laterally Graded Multilayer (LGML) mirrors, and Charge Coupled Device (CCD) detectors to measure polarization. We will describe the design of the instrument post-critical design review, the status of flight hardware testing, and payload assembly.
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All authors Sarah N.T. Heine, Herman L. Marshall, Alan Garner, F. Elio Angile, C. Marc Baker, Stephen Bongiorno, Leonardo Drake, H. Moritz Gunther, Ralf K. Heilmann, Beverly LaMarr, Sean McNeil, Jill Juneau, Swati Ravi, Eric Gullikson

High Energy Astrophysical Phenomena

Depolarization Induced by Rapid Polarization Angle Swings: A Common Feature of Pulsars and Fast Radio Bursts?

Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang et al. (+1 more)

The polarization angle (PA) of pulsars and fast radio bursts (FRBs) provides a useful diagnostic of the magnetic fields in their emission regions and is therefore crucial for understanding their radiation and origins. Within a general geometric framework for polarized emission from a rotating neutron star, we suggest a possible anti-correlation between the degree of linear polarization $\Pi_\text{L}$ and $d\text{PA}/dt$, the time derivative of the PA, as a common feature of pulsars and FRBs. The depolarization arises from the incoherent superposition of radiation with different polarization directions within the observable part of the emission region, and is detectable only when the PA swing is steep enough. We test this conjecture using a sample of radio pulsars and find possible evidence for the expected anti-correlation in a subset of pulsars. Whether this relation holds in FRBs remains uncertain due to limited observational data. Identification of this feature would not only provide insights into the rotating magnetospheric origin of FRBs, but also place constraints on the spin periods and geometric parameters of the neutron stars that power these mysterious bursts.
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All authors Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang, Zi-Gao Dai

Earth and Planetary Astrophysics

Rotation and Mutual Eclipse Events Season in the Kuiper Belt: (524366) 2001 XR$_{254}$

Audrey Thirouin, William M. Grundy, Scott S. Sheppard et al. (+3 more)

(524366) 2001 XR$_{254}$ is a dynamically Cold Classical Kuiper Belt Object that is a nearly equal-sized wide binary whose upcoming mutual events season makes it a particularly valuable target for physical characterization. In advance of the mutual eclipse events, we conducted a ground-based photometric observing campaign between 2021 and 2026 using the Lowell Discovery Telescope to investigate the rotational and physical properties of the system, to refine predictions for its future mutual events, as well as provide a lightcurve we can use as a baseline to identify eclipse events superimposed with the rotation. We derive a double-peaked asymmetric rotational lightcurve with a period of 11.17$\pm$0.04 h and a lightcurve amplitude of 0.42$\pm$0.04 mag. The lightcurve presents a sharp V-shaped minimum consistent with the primary being a close/contact binary, possibly making this a triple system. Using the Keplerian mutual orbit solution, we model the upcoming mutual event season expected between $\sim$2031 and $\sim$2040 and present some individual events for future campaigns. 2001 XR$_{254}$ is one of the few wide binary Kuiper belt systems with a well-determined mutual orbit and a soon observable mutual eclipse event season. Mutual event observations of this possible triple system will provide a rare opportunity to improve component sizes, shapes, densities, and surface properties, offering insights into the formation of the Kuiper Belt.
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All authors Audrey Thirouin, William M. Grundy, Scott S. Sheppard, Keith S. Noll, José María Gómez-Limón, Benjamin Proudfoot

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

Tidal Love numbers of multi-state Boson stars

Xin-Lei Zhao, Jun-Ru Chen and Yong-Qiang Wang

In this paper, we calculate the tidal Love numbers of multi-state boson stars (MSBSs) composed of ground state and first excited state complex scalar fields. Under synchronized and nonsynchronized frequency conditions, the background solutions of MSBSs are classified into single-branch and double-branch types. The field functions, ADM mass, and binding energy of different solutions are discussed. We then calculate the quadrupolar ($\ell=2$) electric and magnetic tidal Love numbers for branches containing stable solutions. Our results show that the electric tidal Love numbers are initially positive and then suddenly transition to negative values. This phenomenon occurs when the parameters satisfy $\tilde{\mu}_1 > 0.891$ or $\tilde{\omega}_0 > 0.777$; for smaller values of these parameters, the electric Love numbers remain positive. The magnetic tidal Love numbers are always negative, with absolute values smaller than those of the electric tidal Love numbers.
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Earth and Planetary Astrophysics

Setting the Stage: The Early History of the Solar System

Antǵona Segura, Rachel L. Smith, Myriam Telus et al. (+3 more)

This article reviews the early history of our solar system from an astrobiological perspective and presents evidence from meteorites and astronomical observations. The purpose is to trace the formation of key molecules that participated in the building blocks of life. The Sun and its planetary system started from a section of a molecular cloud that collapsed into a protoplanetary disk. In the center of the protoplanetary disk, the protosun heated the surrounding material. The dust and gas inherited from the cloud remained pristine farther away from the protostar, while new compounds were created in the gas and on the icy mantles of the dust. The dust accreted into pebbles, pebbles formed planetesimals, and planetesimals collided and accreted pebbles to create planets. Meanwhile, the protosun became the Sun when its core reached the pressure and temperature required to transform hydrogen into helium. During this process, the Sun emitted high-energy radiation and particles that impacted the chemistry in the disk and the early evolution of the terrestrial planets.
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All authors Antǵona Segura, Rachel L. Smith, Myriam Telus, Edward Schwieterman, Rachel Osten, Sukrit Ranjan

Wednesday 29 July

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

Stasis Combs: Gravitational-Wave Signatures of Recurrent Cosmological Stasis

Gabriela Barenboim and Anne-Katherine Burns

Cosmological stasis can recur multiple times, and each occurrence imprints a characteristic feature on the inflationary gravitational wave background (IGWB). We extend the single-epoch spectral template to an arbitrary number $N$ of consecutive stasis epochs, deriving a closed-form $N$-epoch piecewise template that factorizes cleanly: the amplitude steps at each break are determined entirely by the local equation of state $w_s^{(i)}$ of that epoch, while the inter-epoch plateau levels encode the accumulated spectral tilt from all prior epochs. Each resolved spectral feature yields an independent test of the Bessel-function consistency relation $C^2 = C^2(\alpha)$ established in~\cite{BarenboimBurns:paper1}, and the probability that $N$ such tests are simultaneously satisfied by a non-stasis spectrum falls sharply with $N$, making a confirmed multi-epoch comb the strongest available discriminator against constant-$w$ alternatives. We apply the formalism to the triple-stasis scenario of~\cite{Dienes:2023ziv}, which chains three pairwise stasis mechanisms (matter/radiation, vacuum-energy/matter, vacuum-energy/radiation) sequentially. For each block we derive the conditions under which the epoch lies within the template's validity range $w_s > -1/3$. We show that the Fig.~3 benchmark of~\cite{Dienes:2023ziv} falls outside this range and identify parameter choices that are both physically realizable and accessible to the template. We validate the inter-plateau ratio predictions numerically for representative two- and three-block chains, and work out the touching-epoch limit in which consecutive blocks share a break frequency without an intervening radiation-dominated interval. Finally, we discuss the detectability of a variety of multi-epoch stasis scenarios and give the minimum detectable tensor-to-scalar ratio as a function of the number of recurrent stasis epochs.
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High Energy Astrophysical Phenomena

Narrow Population Inference Enhanced by Analytical Likelihood Models

Meesum Qazalbash, Sophiya Mehra, Muhammad Zeeshan et al. (+2 more)

The growing catalog of gravitational-wave events has revealed substantial diversity in the properties of compact-binary mergers. However, commonly used population-inference methods based on discrete posterior samples can struggle to constrain narrow population features, resulting in biased or unstable estimates of population hyperparameters. We first demonstrate this limitation using a toy population model by comparing parameter recovery with a continuous likelihood model against discrete approximations constructed from $10^3$, $10^4$, and $10^5$ samples. We then perform the same comparison using synthetic eccentric and multisource populations introduced in previous studies. Although the continuous and discrete approaches yield broadly consistent results, the continuous approximation more accurately recovers the parameters of narrow simulated populations. In particular, while both methods produce similar mass distributions, appreciable differences arise for narrowly distributed parameters such as spin and eccentricity. Our results indicate that the continuous approach provides more reliable inference for spin and eccentricity, whose narrow population distributions can be inadequately represented by finite sample sets. Continuous likelihood models therefore offer a valuable tool for improving population inference and extracting more robust information about the formation and evolution of compact-binary systems.
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All authors Meesum Qazalbash, Sophiya Mehra, Muhammad Zeeshan, Vera Delfavero, Richard O'Shaughnessy

Earth and Planetary Astrophysics

Stellar impact on exoplanetary atmospheric evolution and habitability

Antígona Segura, Manuel Güdel, Konstantin Herbst et al. (+4 more)

This chapter will review the deep connection of planetary habitability and stellar irradiation. We present the long-term stellar evolution as one of the drivers of atmospheric escape and climate changes on exoplanets, as well as the chemistry driven by stellar UV and stellar energetic particles. Habitability is presented in the context of short and long-term stellar variability and evolution to layout what we understand and what we need to know about stellar irradiation to constrain our planetary atmospheric models and choose the best targets for future missions that may characterize those exoplanets.
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All authors Antígona Segura, Manuel Güdel, Konstantin Herbst, Dibyendu Nandy, Arghyadeep Paul, Raissa Estrela, Allison Youngblood

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

Structural morphology and the gravitational arrow of time

Julian Barbour, Francisco S. N. Lobo and Maria I. R. Lourenço

The Newtonian $N$-body problem in the zero-energy, zero-linear-momentum, and zero-angular-momentum sector provides a time-reversal-invariant setting in which generic complete solutions possess a Janus point and exhibit a gravitational arrow on both branches away from it. The dimensionless variety $V$, a global scale-invariant measure of clustering contrast, is not pointwise monotonic but fluctuates while growing between rising bounds away from the Janus region. Central configurations are critical shapes of the same scale-invariant landscape and therefore provide controlled probes of the structural information encoded by $V$. We investigate this question for two planar $N=5000$ central configurations using the numerical particle-coordinate data. Local morphology is quantified by the six-neighbour anisotropy $A_6$, which ranges from $0$ for an isotropic local environment to $1$ for an effectively one-dimensional one. Although the varieties of the two configurations differ by only $1.686\%$, their mean anisotropies differ by $156.8\%$, from $0.1331$ to $0.3419$. Moreover, $18.1\%$ of the particles in the higher-variety configuration satisfy $A_6>0.5$, whereas none do so in the lower-variety configuration. The anisotropy ordering persists for all tested neighbourhood sizes $4\le k\le12$, and the principal contrast survives a dimensionless close-pair robustness test. For this pair of critical shapes, nearby values of the global variety therefore coexist with markedly different local geometrical organization. Thus the scalar quantity whose long-term behavior characterizes the BKM gravitational arrow does not, by itself, uniquely specify morphology. This identifies local relational observables as a complementary level of description and provides a quantitative bridge between the static shape-space landscape and morphology along genuine Janus-point histories.
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Cosmology and Nongalactic Astrophysics

Unified dark sector approaches to cosmological tensions

Sergio Sevillano Muñoz and Mark Trodden

We present an analytical study of minimal mass-varying dark matter models, in which a single scalar field controls the dark matter mass, focusing on their utility in simultaneously addressing multiple cosmological tensions. We show that such minimal models can naturally become relevant at two critical epochs in the history of the Universe; matter-radiation equality and the present day, generating an early dark energy-like energy injection, as motivated by the Hubble tension, and an apparent phantom crossing, as suggested by baryon acoustic oscillation data from the DESI project. Crucially, the characteristic timing of these effects is tied to the cosmological background evolution itself, rather than specific energy scales. In addition, the intermediate evolution reduces the clustering matter density and can therefore lower $S_8$, in the direction preferred by data, while avoiding new long-range interactions. We derive analytic arguments to understand the conditions for these effects to arise in the same model and assess whether they can occur without introducing additional fine-tuning. This provides a simple framework for identifying which potentials and couplings to dark matter can simultaneously affect early- and late-time cosmological tensions.
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Earth and Planetary Astrophysics

Neptune's Inner Moons and Rings Are Exposed Icy Body Interiors

M. Ryleigh Davis, Matthew Belyakov, Ian Wong et al. (+2 more)

Neptune's single large moon, Triton, is accompanied by a set of dusty rings and small moons whose composition and origin are uncertain. Using the James Webb Space Telescope, we observed Neptune's rings and three moons: Larissa, Galatea, and Proteus. Remarkably, these moons and rings have spectra that are distinct from other outer solar system objects and show no evidence of water ice, despite hosting deep 3 micron OH absorption bands. Additionally, Larissa, Galatea, and the rings show a compositional signature unique among outer solar system bodies: a 2.72 micron absorption band diagnostic of magnesium-rich phyllosilicates - a signpost of extensive aqueous alteration. These minerals likely formed in the interior of primordial satellites destroyed during Triton's violent capture or a tidally shredded dwarf planet. Our findings suggest that Neptune's present-day inner moons and rings reaccreted from this deep interior material and therefore uniquely access the interior composition of icy outer solar system differentiated bodies.
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All authors M. Ryleigh Davis, Matthew Belyakov, Ian Wong, Zachariah Milby, Michael E. Brown

High Energy Astrophysical Phenomena

JWST Spectra Indicate a Large Mass of Postshock Dust Formed by SN 2010jl

Nathan Smith, Melissa Shahbandeh, Ori D. Fox et al. (+22 more)

We present new JWST mid-IR spectra and ground-based optical spectra of the lingering source at the position of SN 2010jl, which was a relatively nearby superluminous Type IIn supernova having strong interaction with circumstellar material (CSM). Early-time data showed evidence of dust, interpreted as either pre-existing CSM dust, or as newly formed dust in the SN ejecta and post-shock region. At 13 yr post explosion, JWST reveals a strong MIR excess from warm dust, with broad features at 10-15 $\mu$m. Our analysis reveals a minimum dust mass of $>$0.11 $M_{\odot}$, and a more likely value of 0.2 $M_{\odot}$ or more because the dust is optically thick. This is among the largest masses of SN-produced dust yet measured without far-IR/submm data, and greatly exceeds SN 2010jl's dust mass inferred around 2-3 yr post-explosion. Ground-based optical spectra confirm the presence of a young massive cluster at the SN position, and confirm that blueshifted line profiles persisting until the latest epochs arise from dust formed in the post-shock region. The warmest dust emitting in the MIR is likely to be the same post-shock dust causing the blueshift. The JWST spectrum also reveals silicate absorption, which may arise from cool SN ejecta dust along the line of sight to the receding shock. The large mass of post-shock dust in SN 2010jl suggests that strong CSM interaction promotes efficient dust production, where the new post-shock dust will survive. If strongly interacting SNe are common in the early Universe, this may contribute significantly to dust seen in infant galaxies.
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All authors Nathan Smith, Melissa Shahbandeh, Ori D. Fox, Thomas Moore, Jennifer E. Andrews, Thomas G. Brink, Eli Dwek, Michael Engesser, Alexei V. Filippenko, Bryony Nickson, Tea Temim, Yi Yang, WeiKang Zheng, Chris Ashall, Raphael Baer-Way, Geoffrey C. Clayton, Jacob E. Jencson, Joel Johansson, Zachary G. Lane, Dan Milisavljevic, Armin Rest, Arkaprabha Sarangi, Tamas Szalai, Schuyler D. Van Dyk, Brian J. Williams

Astrophysics of Galaxies

Stellar photoionisation modelling in SYNTHESIZER

Aswin P. Vijayan, Stephen M. Wilkins, Sophie L. Newman et al. (+5 more)

Emission from photoionised gas surrounding young stellar populations ($H\text{II}$ regions) provides critical diagnostics of the physical conditions in star forming galaxies. This emission constrains the gas properties, the nature of ionising sources, and generates essential features for determining galaxy redshifts. To leverage spectroscopic observations to test galaxy formation models, it is essential to incorporate these emissions into synthetic datasets. Here, we present the integration of photoionised gas emission into the SYNTHESIZER package (https://synthesizer-project.github.io) and demonstrate its application. We quantify the impact of key modelling assumptions - including stellar population synthesis models, initial mass functions, ionisation parameter, gas density, geometry, abundance pattern, elemental depletion, and dust - on spectral diagnostics. Furthermore, we demonstrate the versatility of SYNTHESIZER through its application in different scenarios ranging from exploring emission in toy parametric models to large-volume cosmological simulations with realistic star formation and metal enrichment histories. Taken together, SYNTHESIZER provides a flexible, physically motivated framework to model stellar and nebular emissions, serving as a vital link between theory and observations in the era of next-generation spectroscopic missions.
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All authors Aswin P. Vijayan, Stephen M. Wilkins, Sophie L. Newman, Christopher C. Lovell, William J. Roper, Sabrina Berger, Thomas Harvey, Jack C. Turner

High Energy Astrophysical Phenomena

On the triple nature of the PSR J0435+3233 system

Paulo C. C. Freire, Colin J. Clark, Cees G. Bassa et al. (+4 more)

The recent pulsar timing ephemeris of PSR J0435+3233 indicates that this millisecond pulsar (MSP) has a spin-down rate that is much higher than observed in other MSPs and challenges our understanding of the formation and evolution of MSPs. We propose that this system is a hierarchical triple, and that the high spin-down rate is caused by varying acceleration due to a tertiary in a wide orbit. We use pulsar timing methods with radio and gamma-ray observations of PSR J0435+3233 to determine the system properties. We find that a hierarchical triple timing model describes the timing observations of PSR J0435+3233 and that this results in the detection of gamma-ray pulsations back to the beginning of the Fermi Large Area Telescope (LAT) data in 2008. The intrinsic spin-down rate remains uncertain as it correlates with the parameters of the outer orbit, but large spin-down rates are excluded and the intrinsic rate is at least two orders of magnitude lower than the observed rate, in line with other Galactic MSPs. We identify a star located 11 mas from the pulsar position as the optical counterpart to the tertiary companion. From the 1.5-2.5 kpc distance and colours, we infer that the tertiary is a 1.2-solar mass F-type main-sequence star. Along with the pulsar binary, it orbits the common centre of mass with an eccentric (e ~ 0.6), wide (~70 yr) orbit that is likely seen at a low orbital inclination. We conclude that PSR J0435+3233 is a hierarchical triple system. We discuss the motivation and prospects for the continued study of this system. Spectral measurements of the outer star in addition to continued astrometric measurements will yield mass ratio and inclination estimates, while continued pulsar timing may yield a tighter constraint on violations of the Strong Equivalence Principle than are currently obtained from PSR J0337+1715.
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All authors Paulo C. C. Freire, Colin J. Clark, Cees G. Bassa, Guillaume Voisin, Rutger van Haasteren, Lars Nieder, Benjamin W. Stappers

Instrumentation and Methods for Astrophysics

Compton Polarimeter Prototype for the CUbesat Solar Polarimeter (CUSP) mission

Nicolas De Angelis, Andrea Alimenti, Riccardo Campana et al. (+41 more)

The space-based CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band (25-100 keV) by means of a dual-phase Compton polarimeter. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures of our star with its unprecedented sensitivity to solar flare polarization. CUSP is a project under development as part of the Alcor Program of the Italian Space Agency aimed at developing new CubeSat missions. In the frame of CUSP's Phase B, which started in December 2024, a flight-representative prototype of the Compton polarimeter has been developed and characterized with hard X-ray sources in the laboratory. This prototype consists of a 4$\times$4 central matrix of plastic scintillator bars surrounded by 4 strips of 8 elongated GAGG scintillators, respectively coupled to a multi-anode photomultiplier tube and arrays of avalanche photodiodes. These sensors are read out by custom front-end electronics based on MAROC-3A and SKIROC-2A ASICs with a Xilinx Artix 7 FPGA. The plastic scintillators act as scatterers, while the GAGG bars fully absorb the scattered photons. Coincident plastic-GAGG events allow for reconstructing the Compton scattering direction, whose distribution allows for inferring the polarization parameters of the source. We report here the measured performance of the polarimeter prototype using well-known radioactive isotopes and X-ray tubes, allowing us to assess the performance of our polarimeter prototype over the full 25-100 keV energy range.
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All authors Nicolas De Angelis, Andrea Alimenti, Riccardo Campana, Mauro Centrone, Giovanni De Cesare, Ettore Del Monte, Sergio Di Cosimo, Enrico Costa, Sergio Fabiani, Abhay Kumar, Pasqualino Loffredo, Giovanni Lombardi, Gabriele Minervini, Fabio Muleri, Paolo Romano, Alda Rubini, Enrico Silva, Paolo Soffitta, Giovanni Cucinella, Vito Di Bari, Simone Di Filippo, Andrea Negri, Massimo Perelli, Davide Albanesi, Valerio Campamaggiore, Giulia de Iulis, Andrea Del Re, Paolo Leonetti, Alessandro Zambardi, Ilaria Baffo, Pierluigi Fanelli, Costantino Zazza, Andrea Curatolo, Nicolas Gagliardi, Dario Modenini, Daniele Pecorella, Alice Ponti, Paolo Tortora, Valerio Vagelli, Daniele Brienza, Immacolata Donnarumma, Matteo Mergè, Emanuele Zaccagnino, Alessandro Turchi

Instrumentation and Methods for Astrophysics

Testing of machine learning wavefront sensing algorithms on the Tiny Observatory for Telescope Optimization (TOTO) testbed

Sanchit Sabhlok, Solvay A. Blomquist, Maggie Y et al. (+16 more)

Phase retrieval techniques are utilized to correct low order wavefront aberrations originating from misalignments of the optical system in space based telescope concepts. Traditional phase retrieval involves observation of the Point Spread Function (PSF) and a diversity measurement, usually focus diversity although other measures are possible, to reconstruct the incident wavefront at the science detector. We consider a Machine Learning model trained originally on simulated data, and then augmented with real focus diversity data from the Tiny Observatory for Telescope Optimization (TOTO) testbed at the University of Arizona. We then compare the wavefront sensing performance of the Machine Learning model with known truth values of the generated dataset. The model predictions for low order Zernikes on TOTO data after training and validation show a reasonable agreement with the true Zernike coefficients.
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All authors Sanchit Sabhlok, Solvay A. Blomquist, Maggie Y, Kautz, Debstuti Biswas, Kevin Derby, Jaren N. Ashcraft, Hyukmo Kang, Simran Agarwal, Alexandra Kupersmith, Adam Schilperoort, Stephanie F. Rinaldi, Kelsey L. Miller, Kyle J. Van Gorkom, Corey Fucetola, Patrick Ingraham, Ewan S. Douglas, Heejoo Choi, Daewook Kim