High Energy Astrophysical Phenomena · Cross-listed from hep-ph
An Excited Dark Matter Solution to the MeV Galactic Center Excesses
Shyam Balaji, Damon Cleaver and Pedro De la Torre Luque
Recent COMPTEL data analysis reveals a $\sim$ 2 MeV continuum excess whose spatial distribution closely matches the long-standing 511 keV line observed by INTEGRAL/SPI, indicating a common population of low-energy positrons that is difficult to reconcile with known astrophysical sources or standard thermal dark matter (DM). We show that a minimal Excited Dark Matter (XDM) model naturally explains these features. In this scenario a DM particle $\chi$ is inelastically upscattered into an excited state $\chi^*$, followed by de-excitation $\chi^*\to\chi e^+ e^-$ producing $\sim$2 MeV positrons that reproduce the 511 keV line morphology and the COMPTEL MeV continuum. Using a full
cosmic-ray (CR) propagation treatment, we obtain an excellent fit for $m_\chi\simeq$ 1.5 TeV DM particle with mass-splitting $\Delta m =m_{\chi^*}-m_\chi \simeq$ 4 MeV for an inelastic
geometric scattering cross section of $\sigma_\textrm{mr}= 3-4\times 10^{-23}\,\textrm{cm}^2$. The same positrons supply a substantial, radially flat contribution to the anomalous Central Molecular Zone (CMZ) ionization rate. This is the first unified treatment of XDM-induced positrons across all three observables, yielding correlated MeV signatures testable by upcoming missions targeting the
Galactic MeV band.
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High Energy Astrophysical Phenomena
Exploring the origins of high-velocity features in SNe Ia with the spectral synthesis code TARDIS
Luke Harvey, Kate Maguire, Alexander Holas et al. (+8 more)
Appearing as secondary higher-velocity absorption components, high-velocity features (HVFs) have been observed in several absorption lines in many Type Ia
supernovae (SNe Ia). The frequency and ubiquity of these components in silicon and calcium features specifically indicates that the mechanism through which they form must be common occurrence among the majority of SNe Ia. Here we present modelling of the HVF
evolution in a sample of six well observed SNe Ia with the radiative-transfer code tardis. A base model is derived for each of the SNe to reproduce the photospheric velocity components, followed by a grid of simulations with Gaussian enhancements to the density profile at high velocities. We train a set of neural networks to emulate the impact of these density enhancements upon the simulated silicon line profile. These networks are subsequently used within a Markov-Chain Monte Carlo (MCMC) framework to infer the density enhancement parameters that most closely reproduce the HVF
evolution. While we obtain good matches for the silicon profile, we find that a single density enhancement alone cannot simultaneously produce the observed silicon and calcium HVF
evolution. Our findings indicate that neither the delayed-detonation mechanism, nor the double-detonation mechanism can produce these HVFs, suggesting that something may be missing from the models.
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All authors Luke Harvey, Kate Maguire, Alexander Holas, Joseph P. Anderson, Ting-Wan Chen, Lluís Galbany, Santiago González-Gaitán, Mariusz Gromadzki, Tomas E. Müller-Bravo, Giuliano Pignata, Ivo R. Seitenzahl
Solar and Stellar Astrophysics
The chemical DNA of the Magellanic Clouds V. R-process dominates neutron capture elements production in the oldest SMC stars
Lorenzo Santarelli, Marco Palla, Alessio Mucciarelli et al. (+4 more)
We present the chemical abundances of Fe, alpha- and
neutron-capture elements in 12 metal-poor Small Magellanic Cloud (SMC)
giant stars, observed with the high-resolution spectrographs UVES/VLT and MIKE/Magellan. These
stars have [Fe/H] between -2.3 and -1.4 dex, 10 of them with [Fe/H]<-1.8 dex. According to theoretical age-
metallicity relations for this
galaxy, these
stars formed in the first Gyr of life of the SMC and represent the oldest SMC
stars known so far. [alpha/Fe] abundance ratios are enhanced but at a lower level than MW metal-poor
stars, as expected according to the slow
star formation rate of the SMC. The sample exhibits a large
star-to-
star scatter in all the
neutron-capture elements. The two r-process elements measured in this work (Eu and Sm) have abundance ratios from
solar up to +1 dex, three of them with [Eu/Fe]>+0.7 dex and labeled as r-II
stars. This [r/Fe] distribution indicates that the r-process in the SMC can be extremely efficient but is still largely affected by the
stochastic nature of the main sites of production and the inefficient gas mixing in the early SMC
evolution. A similar scatter is observable also for the s-process elements (Y, Ba, La, Ce, Nd), with the
stars richest in Eu also being rich in these s-elements. Also, all the
stars exhibit subsolar [s/Eu] abundance ratios. At the
metallicities of these
stars, the production of
neutron-capture elements is driven by r-process, because the low-mass AGB
stars have not yet evolved and left their s-process signature in the interstellar medium. We also present
stochastic chemical
evolution models tailored for the SMC that confirm this scenario.
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All authors Lorenzo Santarelli, Marco Palla, Alessio Mucciarelli, Lorenzo Monaco, Deimer Antonio Alvarez Garay, Donatella Romano, Carmela Lardo
High Energy Astrophysical Phenomena
A minimalist approach to BL Lacertae: explaining gamma-ray spectral and temporal variability with a single physical parameter
Raniere de Menezes, Francesco Massaro, Elisa Visentin et al. (+2 more)
The eponymous BL Lac object BL Lacertae is one of the most well-monitored active
galactic nuclei, frequently observed from
radio to gamma rays. Its relatively soft $\gamma$-ray spectrum peaks near 500~MeV, and since 2020 it has undergone an exceptional series of flaring episodes. The observed emission is well described by synchrotron self-Compton (SSC) models, with negligible contribution from external seed
photons. We investigate the physical origin of BL~Lacertae's $\gamma$-ray temporal and spectral variability using data from the Large Area
Telescope (LAT) on board the
Fermi Gamma-ray Space
Telescope, and show that this variability can be explained by a single varying parameter, namely the electrons' peak energy, $\gamma_p$, under a single-zone SSC scenario with a log-
parabolic electron distribution. We use a Markov chain Monte Carlo to estimate the spectral parameters of BL Lacertae over time, selected from an adaptive-binned gamma-ray light curve. We then study the correlation between the inverse Compton peak luminosity, $L_{IC}$, and the position of this peak on the SED energy axis, $E_p$, and compare it with what is expected for a single-zone SSC scenario when only one parameter is free to vary. We find a correlation $L_{IC} = 10^{42.33\pm0.15\pm0.18_{sys}}E_p^{0.98\pm0.05\pm0.06_{sys}}$, consistent, within the errors, with the linear relation $L_{\mathrm{IC}} \propto E_p$, expected when $\gamma_p$ is the only free parameter in the assumed SSC model. This result supports a minimalist SSC scenario in which changes in $\gamma_p$ dominate the observed temporal and spectral variability of BL~Lacertae.
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All authors Raniere de Menezes, Francesco Massaro, Elisa Visentin, Federico Di Pierro, Haocheng Zhang
Astrophysics of Galaxies
Confirming membership in Local Group galaxies with the Dark Energy Spectroscopic Instrument Data Release 1
Federico Sestito and Chiaki Kobayashi
We use the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) to identify
stellar members of the Local Group
dwarf galaxies. We cross-match DESI targets with candidate members that are based on
Gaia proper motions, positions, and photometry. The addition of DESI radial velocities enables secure membership determination in 15 systems. Our results confirm that
Gaia-based selection
algorithms are effective in minimising foreground contamination. Two
stars are found to be associated with DES~J0225$+$0304; if this is the case, then it leads to the first determination of the systemic radial velocity (RV$_{\rm{sys}}=-150.0\pm7.0$~km~s$^{-1}$). Draco and Sextans are the
galaxies with the largest number of members. We focus on Sextans and, for the first time with DESI, trace its
stellar kinematics to large radii (up to $\sim$10~half-light radii). We find that the metal-poor population exhibits a higher velocity dispersion and extends to larger radii, whereas the metal-rich population is kinematically colder and centrally concentrated. The
metallicity gradient is steeper in the inner regions of Sextans ($\sim -12\times 10^{-3}$~dex~arcmin$^{-1}$ or $\sim -0.36$~dex~kpc$^{-1}$), while almost no gradient in the outskirts, hinting for an ex-situ
halo or for an “outside-in”
star formation. Although DESI [$\alpha$/Fe] ratios for Sextans
stars with $\FeH\gtrsim-2.0$ are in line with literature values, those for very metal-poor
stars ($\FeH\lesssim-2.0$) present a large scatter and strong anti-correlation with
metallicity, warranting a caution for using DESI abundances in this regime. With a less strict selection, we identify 8 ultra metal-poor ([Fe/H]~$< -4$) candidates that require higher signal-to-noise ratio spectroscopic observations to determine their
metallicities.
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Solar and Stellar Astrophysics
Hydrodynamical mass-loss rates for Very Massive Stars. I. Investigating the wind kink
Gautham N. Sabhahit, Jorick S. Vink and Andreas A. C. Sander
Radiation-driven winds are ubiquitous in massive
stars, but in Very Massive
Stars (VMSs), mass loss dominates their
evolution, chemical yields, and ultimate fate. Theoretical predictions have often relied on extrapolations of O
star prescriptions, likely underestimating true VMS mass-loss rates. In the first of a series of papers on VMS wind properties, we investigate a feature predicted by Monte Carlo (MC) simulations: a mass-loss `kink' or upturn where the single-scattering limit is breached and winds transition from optically thin to optically thick. We calculate hydrodynamically consistent non-LTE atmosphere models using the PoWR$^\mathrm{HD}$ code, with a grid spanning $40-135M_\odot$ and 12-50 kK at fixed $\log(L_\star/L_\odot) = 6.0$ and
solar-like
metallicity with $Z=0.02$. Our models confirm the existence of the kink, where the wind optical depth crosses unity and spectral morphology shifts from O
star to WNh types. The predicted location of the kink coincides with the transition
stars in the
Galactic Arches cluster and reproduces the model-independent transition mass-loss rate of $\log(\dot{M}_\mathrm{trans}) \approx -5.16$ from Vink & Gräfener (2012). For the first time, we locate the kink at $\Gamma_\mathrm{e} \approx 0.43$ ($M_\star \approx 60M_\odot$) without relying on uncertain
stellar masses. Above the kink, mass-loss rates scale much more steeply with decreasing mass (slope ~ 10), in qualitative agreement with MC predictions. We additionally identify two bistability jumps in the mass loss driven by Fe ionisation shifts: the first from FeIV to FeIII near 25 kK and the second from FeIII to FeII near 15 kK. Our models thus provide the first comprehensive confirmation of the VMS mass-loss kink while establishing a mass-loss relation with complex mass and temperature dependencies with consequences for
stellar evolution, chemical yields, and the black hole mass spectrum.
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Astrophysics of Galaxies
Resolving dust and Ly{\alpha} emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS
V. Markov, M. Bradač, V. Estrada-Carpenter et al. (+20 more)
Lyman $\alpha$ emission is highly sensitive to
dust and neutral hydrogen and is therefore expected to be strongly suppressed in dusty or gas-rich
galaxies during the epoch of reionization (EoR). Nevertheless, numerous moderately dusty Ly$\alpha$ emitters (LAEs) are observed at this epoch, suggesting that complex interstellar medium (ISM) geometries and feedback-driven
outflows may facilitate Ly$\alpha$ escape. We investigate the
dust, gas, and
stellar properties of the gravitationally lensed LAE HCM 6A at $z=6.5676$ to characterize its multiphase ISM and the physical conditions regulating Ly$\alpha$ escape. We combine JWST/NIRISS slitless spectroscopy, HST+JWST/NIRCam imaging, and JWST/NIRSpec slit spectra from the CANUCS program. Using a customized BAGPIPES SED-fitting framework with a flexible attenuation law, we derive
stellar, nebular, and
dust properties on integrated ($\sim$kpc), slit-level ($\sim$0.1 kpc), and pixel-level ($\sim$25 pc) scales, enabled by strong
lensing ($\mu \approx 8.3$-$9.1$). A Ly$\alpha$ map from SLEUTH traces the spatial distribution of Ly$\alpha$ emission. We measure an unlensed
stellar mass of $\log M_\ast = 8.3$-$8.4$ and an intrinsic UV magnitude of $M_{\rm UV} = -19.8 \pm 0.1$. The older region (S1) is moderately dusty with consistent
stellar and nebular attenuation indicators, implying a uniform ISM geometry, while the youngest region (S3) shows strong discrepancies among
dust tracers, indicating a feedback-shaped multiphase ISM. Ly$\alpha$ emission arises primarily from S3, where a
dust-cleared central clump enables efficient Ly$\alpha$ escape. We find Calzetti-like attenuation curves with a UV bump that strengthens with
stellar age and decreasing $A_V$. Our observations provide a uniquely detailed, spatially resolved view of a moderately dusty LAE during the EoR, demonstrating how feedback and multiphase ISM structure govern Ly$\alpha$ escape.
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All authors V. Markov, M. Bradač, V. Estrada-Carpenter, G. Desprez, G. Rihtaršič, J. Judež, R. Tripodi, M. Sawicki, G. Noirot, N. Martis, C. Willott, R. Abraham, Y. Asada, G. Brammer, J. Matharu, A. Muzzin, G. T. E. Sarrouh, S. Withers, A. Ferrara, S. Fujimoto, S. Gallerani, I. Goovaerts, A. Harshan
Earth and Planetary Astrophysics
Hot Jupiters in Old Wide-Binary Systems
Evgeni Grishin, Jet Winter and Jaime A. Alvarado-Montes
Hot Jupiters (HJs) are
giant planets with orbital periods shorter than $10$ days, found around $\sim 0.5$-$1\%$ of Sun-like
stars. Their origins remain debated despite decades of study. The high prevalence of
stellar companions, the eccentricity distribution of 'Cold' Jupiters on longer orbits, and the wide range of
stellar spin-orbit misalignments support high-eccentricity migration:
planets are excited to eccentric orbits and subsequently circularised via
tidal dissipation. Existing high-eccentricity migration models, however, are inefficient in converting the initial population of Cold Jupiters to HJs. Current models reproduce at most $\lesssim 30\%$ of observed HJs, while the resulting Cold/Hot Jupiter ratios ($\gtrsim 30$) overproduce the observed values of $10$-$15$. These models also fail to form HJs around old
stars ($\gtrsim 3$ Gyr) on short
tidal decay timescales (e.g., $<40$ Myr). Here we show that wide binaries ($a > 10^3$ au) perturbed by the
Galactic tidal field produce $1.8\pm 0.14$ more HJs compared to isolated binary systems, accounting for $26$-$40\%$ of the observed population under conservative assumptions. Wide-binaries predominantly produce Gyr-old systems, consistent with the host-age distribution for $t \ge 2.5\ \rm Gyr$. In $\sim 20\%$ of cases, wide-binary perturbations eject
giant planets entirely, resolving the Cold/Hot Jupiter ratio discrepancy while naturally seeding the population of free-floating
giant planets. In our dynamical framework, wide binaries emerge as active
agents that reshape planetary demographics across billions of years. These results will be decisively tested by forthcoming
exoplanet and microlensing surveys.
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Instrumentation and Methods for Astrophysics
Direct imaging characterization of cool gaseous planets
Michiel Min, Jo Barstow, Laura C. Mayorga et al. (+19 more)
Cool gas
giant exoplanets, particularly those with properties similar to those of Jupiter and Saturn, remain poorly characterized due to current observational limitations. This white paper outlines the transformative science case for the Habitable Worlds Observatory (HWO) to directly image and spectroscopically characterize a broad range of gaseous
exoplanets with effective temperatures below 400 K. The study focuses on determining key atmospheric properties, including molecular composition, cloud and haze characteristics, and temperature structure, across
planets of varying sizes and orbital separations. Leveraging reflected light spectroscopy and polarimetry, HWO will enable comparative planetology of cool gas
giants orbiting both
solar-type and M-
dwarf stars, bridging the observational gap between hot
exoplanets and
Solar System
giants. We present observational requirements and survey strategies necessary to uncover correlations between atmospheric properties and planetary or
stellar parameters. This effort will establish critical constraints on planetary formation, cloud microphysics, and the role of photochemistry under diverse irradiation conditions. The unique capabilities of HWO will make it the first facility capable of characterizing true exo-Jupiters in reflected light, thus offering an unprecedented opportunity to place the
Solar System in a broader
galactic context.
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All authors Michiel Min, Jo Barstow, Laura C. Mayorga, Hannah Wakeford, Jason Wang, Renyu Hu, Beth Biller, José A. Caballero, Ludmila Carone, Sarah Casewell, Katy L. Chubb, Mario Damiano, Siddharth Gandhi, Antonio García Muñoz, Christiane Helling, Finnegan Keller, Nataliea Lowson, Evert Nasedkin, Ryan MacDonald, Jean-Baptiste Ruffio, Evgenya Shkolnik, Christopher C. Stark
Instrumentation and Methods for Astrophysics
The next frontier in exoplanet science: Imaging our neighbouring planetary systems
Ignas Snellen, Sebastiaan Haffert, Matthew Kenworthy et al. (+1 more)
Transmission and eclipse spectroscopy have been invaluable tools for the characterisation of extrasolar
planet atmospheres. While they will continue to provide many new insights and discoveries in the decade(s) to come, these methods are running up against sources of
stellar noise from
stellar surface inhomogeneities and variability. In this white paper we discuss how the next steps in the characterisation of small, temperate rocky
planets requires high-contrast imaging, making the planetary systems around our closest neighbouring
stars the new frontier in
exoplanet science. The Extremely Large
Telescopes (ELTs) will be at the forefront of this quest. The Planetary Camera and Spectrograph (PCS) on ESO's ELT and GmagAO-X on the GMT are planned to become operational in the 2035-2040 time-frame, allowing the characterisation of up to dozen(s) of rocky
planets around nearby red
dwarf stars. We discuss what role there will be still to play for ground-based
exoplanet characterisation in the era of the space-borne Habitable Worlds Observatory and LIFE missions.
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All authors Ignas Snellen, Sebastiaan Haffert, Matthew Kenworthy, Tomas Stolker
Cosmology and Nongalactic Astrophysics
Non-parametric exploration of minimally coupled gravity with phantom crossing
Matteo Cataneo and Kazuya Koyama
Recent measurements of the
baryon acoustic oscillations by the Dark Energy Spectroscopic Instrument (DESI), especially when combined with
cosmic microwave background (CMB) and
supernova data, favor a late-time dark energy equation of state that crosses $w=-1$, which has been argued to point toward non-minimal conformal coupling in Horndeski
gravity. We test this interpretation by performing a non-parametric exploration of the minimally coupled, luminal Horndeski subclass known as kinetic
gravity braiding (KGB). Using mochi_class and its manifestly stable effective field theory (EFT) basis implementation, we efficiently scan a broad class of models in which the EFT functions are allowed to vary freely in time, while enforcing the absence of ghost and gradient instabilities from the outset. We identify a set of KGB models that realize phantom crossing and remain broadly consistent with current probes of the background and linear large-scale structure, including CMB temperature and
lensing power spectra,
redshift-space distortions,
cosmic shear, and the cross-correlation between
galaxies and the Integrated Sachs-Wolfe effect. Our results demonstrate that viable phantom-crossing solutions exist without conformal coupling, motivating future full
Bayesian analyses of this model class with non-parametric EFT priors.
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Astrophysics of Galaxies
Identification of periodicities with arbitrary shapes in AGN light curves
Lorenzo Bertassi, Maria Charisi, Riccardo Buscicchio et al. (+3 more)
Massive black hole binaries are expected to be observable as periodic AGN in time-domain photometric surveys. Periodicities may originate from different physical processes, including the intermittent gas feeding of the black holes caused by the time-varying non-axisymmetric binary potential, the Doppler boosting of the flux emitted by individual
accretion discs bound to the orbiting BHs, and the gravitational
lensing of the
accretion disc of one black hole due to the presence of the other. Only the Doppler boost scenario applied to circular binaries with non-modulated
accretion predicts a sinusoidal light curve, while in the general case, binary signals are expected to show more complex periodic patterns. Current searches for massive black hole binaries rely on techniques tailored to quasi-sinusoidal light curves, but fail to identify the more complex periodicities predicted. We present an alternative method that leverages Gaussian processes, making use of a generic periodic kernel flexible enough for the identification of arbitrary periodicities in unevenly sampled light curves with realistic
quasar noise. We demonstrate that it outperforms previously proposed strategies in identifying general periodicities by analysing mock light curves with different baselines. Specifically, we find that our analysis can detect non-sinusoidal periodicities (e.g., sawtooth-shaped) and retrieves a higher fraction of true periodicities when compared to periodogram analysis or Gaussian processes analysis with less flexible periodic kernels. Furthermore, by comparing the retrieved fraction of periodicities between mock PTF light curves and mock LSST light curves, we find that our analysis is most sensitive to the number of observed cycles. The application of this analysis has the potential to greatly increase the scientific return of current and upcoming large time-domain photometric surveys.
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All authors Lorenzo Bertassi, Maria Charisi, Riccardo Buscicchio, Fabio Rigamonti, Jessie Runnoe, Massimo Dotti
Instrumentation and Methods for Astrophysics
XID+PRIMA, II: Stepping Through Hyperspectral Imaging to Deblend PRIMAger Beyond the Extragalactic Confusion Limit
J. M. S. Donnellan, B. Pautasso, S. J. Oliver et al. (+10 more)
The PRIMA mission concept aims to map large areas with spectral coverage and sensitivities inaccessible to previous FIR space
telescopes, covering 25-235 $\mu$m. We synthesise images representing a deep imaging survey, with realistic instrumental and confusion noise, reflecting the latest PRIMAger specifications. We present a new
Bayesian modelling approach XID+stepwise that exploits PRIMAger's hyperspectral imaging to derive self-consistent, informative flux priors by sequentially propagating constraints from short to long wavelengths. With Euclid-like prior source positions, this method recovers fluxes to within 20% down to 0.2-0.7 mJy across 45-84 $\mu$m, which correspond to factors of 1.3-3.5 fainter than the confusion limit. For the most confusion-dominated channels, accurate fluxes are measured down to 0.8, 2.7, 9.3, and 23.4 mJy at 92, 126, 183, and 235 $\mu$m, respectively, which are factors of 2-5 better than the confusion limit. Using a deeper Euclid-based prior catalogue and weak ancillary flux priors at 25 $\mu$m yields further improvements, reaching up to a factor 5 fainter than the confusion limit at 96 $\mu$m. Additionally, we demonstrate that positional priors from blind source detection followed by deblending via XID+ enables PRIMAger to achieve sensitivity beyond the confusion limits using PRIMAger data alone. We show that IR-luminous
galaxies at $z \sim 2$ are robustly detected in a large fraction of the PRIMAger channels (>98% in 12 out of the 16 considered channels), providing dense sampling of the FIR SED even for sources several factors below the classical confusion limit. We explore the impact on our results for a range of systematic effects, including cirrus contamination, optical degradation, and calibration uncertainties. These findings indicate that confusion noise will not limit the key science from PRIMA extragalactic imaging surveys when employing XID+.
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All authors J. M. S. Donnellan, B. Pautasso, S. J. Oliver, M. Béthermin, L. Bing, A. Bolatto, L. Ciesla, W. Jellema, D. Koopmans, A. Pope, S. Serjeant, JD T. Smith, L. Wang
Cosmology and Nongalactic Astrophysics
Bridging Simulations and EFT: A Hybrid Model of the Lyman-Alpha Forest Field
Roger de Belsunce, Boryana Hadzhiyska and Mikhail M. Ivanov
The Lyman-alpha (Lya) forest is a unique probe of cosmology and the intergalactic medium at high
redshift and small scales. The statistical power of the ongoing Dark Energy Spectroscopic Instrument (DESI) demands precise theoretical tools to model the Lya forest. We present a hybrid effective field theory (HEFT) forward model in
redshift space that leverages the accuracy of non-linear particle displacements computed using the N-body simulation suite AbacusSummit with the predictive power of an analytical, perturbative bias forward model in the framework of the effective field theory (EFT). The residual noise between the model and the simulated Lya field has a nearly white (scale-and orientation-independent) power spectrum on quasi-linear scales, substantially simplifying its modeling compared to a purely perturbative description. As a consequence of the improved control over the 3D Lya forest stochasticity, we find agreement between the modeled and the true power spectra at the 5 per cent level down to scales of k <= 1 h/Mpc. This procedure offers a promising path toward constructing efficient and accurate emulators to predict large-scale clustering summary statistics for full-shape cosmological analyses of Lya forest data from both DESI and its successor, DESI-II.
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Cosmology and Nongalactic Astrophysics
Reconstructing spatially-varying multiplicative bias for Stage IV weak lensing galaxy surveys with a quadratic estimator
Konstantinos Tanidis, David Alonso, Lance Miller et al. (+1 more)
We present a quadratic
estimator that detects and reconstructs spatially-varying multiplicative ($m-$) bias in weak
lensing shear measurements, by exploiting the $EB$ mode coupling that it generates. The method combines $E$ and $B$ modes with inverse-variance weights, to yield an unbiased reconstruction of $m(\boldsymbol{\theta})$ to first order. We study the ability of future Stage IV surveys to obtain an unbiased reconstruction of the $m$-bias in differing scenarios, considering differing bias morphologies, and characteristic scales, as well as differing metrics to quantify the signal-to-noise ratio of the reconstructed map. Considering an $m$ pattern repeating on $\sim 1^\circ\times1^\circ$ sky patches, as might be the case for an $m$ field caused by focal-plane systematics. With a Euclid-like
redshift distribution, we find that $\sim5\%$ rms variations in $m$-bias may be detected at the 20$\sigma$ level, after stacking between $\sim400$ and $\sim1000$ patches (rising to between $\sim2800$ and $\sim7600$ for $1\%$ rms variations, data volumes that are becoming available with upcoming surveys), depending on the morphology of the $m$ pattern. We show that these results are robust against the cosmological model assumed in the reconstruction, as well as the presence of intrinsic
alignments or baryonic effects, and that the method shows no spurious response to additive ($c-$) bias. These results demonstrate that percent-level, spatially-varying $m-$bias can be detected at high significance, enabling diagnosis and mitigation in the Stage IV weak
lensing era.
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All authors Konstantinos Tanidis, David Alonso, Lance Miller, Joachim Harnois-Déraps
Cosmology and Nongalactic Astrophysics
A critical value of the inflationary tensor-to-scalar ratio from inhomogeneous inflation
Panagiotis Giannadakis, Matthew Elley, Raphael Flauger et al. (+1 more)
We show that, for a given fixed value of the number of e-folds of the homogeneous solution, inflation succeeds with order unity inhomogeneities in the initial conditions above a characteristic value of the tensor-to-scalar ratio $r$. In practice, we work with an $\alpha$-attractor $T$-model and vary its characteristic scale $\mu$, keeping the initial inhomogeneities in both gradient and kinetic fields of order unity of the inflationary energy scale. Under these conditions, and assuming 100 e-folds for the homogeneous solution, the requirement for 60 e-folds of inflation occurs at a critical characteristic scale $\mu_{crit} \approx 0.02m_{P}$, corresponding to an $r_{crit} \approx 10^{-6}$. Since increasing the amplitude of the inhomogeneities will make inflation less robust and hence require a higher characteristic scale in order for inflation to succeed, for a given number of e-folds achieved by the homogeneous solution $r_{crit}$ is a lower bound.
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All authors Panagiotis Giannadakis, Matthew Elley, Raphael Flauger, Eugene A. Lim
Cosmology and Nongalactic Astrophysics
The impact of non-Gaussianity when searching for Primordial Black Holes with LISA
Antonio Junior Iovino, Gabriele Perna and Hardi Veermäe
LISA can observe cosmological millihertz (mHz) gravitational wave (GW) backgrounds that may offer a decisive test for asteroid-mass
primordial black hole (PBH) dark matter (DM). In standard scenarios, failing to detect a scalar-induced gravitational wave (SIGW) background would exclude the last viable window for PBH DM formed through critical collapse. We show that this conclusion becomes much weaker in the presence of astrophysical foregrounds and strongly non-Gaussian
primordial density perturbations, by studying how these phenomena affect the link between SIGWs and PBHs, and reevaluate LISA's sensitivity to asteroid-mass PBHs. In addition, we analyse the interplay between PBHs and SIGWs to gain further insights into the nature of
primordial non-Gaussianity. We find that uncertainties in $f_{\rm NL}$ can induce substantial uncertainties in the PBH abundance, which ultimately limits LISA's capacity to fully probe the asteroid-mass PBH DM window.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
A post-inflationary kinetic axion
Enrico Morgante and Riccardo Natale
We present a novel realization of
axion kinetic misalignment, triggered by a Hubble-induced phase transition during a post-inflationary stiff (kination) era. A negative
Ricci scalar flips the sign of a non-minimally coupled mass term for a non-minimally coupled complex field $\Phi$, driving its radial mode to large amplitudes via a tachyonic instability. At large $|\Phi|$, higher-dimensional $U(1)$-breaking operators become relevant and impart a kick in the angular direction, generating a conserved $U(1)$ charge that sustains rotation as the
symmetry is approximately restored. Because phases randomize across causally disconnected regions, multiple domains with distinct charges form. The subsequent
axion potential converts the domain charges into an
axion abundance, yielding dark matter even when the net global charge vanishes. We analyze the dynamics through a linear, domain-averaged treatment and identify two thermal histories: (i)
Ricci reheating via saxion decays to
Higgs bosons; (ii) external reheating with efficient damping of saxion energy by
Higgs/
fermion scatterings. The mechanism populates regions underabundant in standard misalignment, which are accessible to next generation
axion searches.
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Solar and Stellar Astrophysics
David H. Brooks, Deborah Baker, David M. Long. Paola Testa et al. (+1 more)
We discuss the
evolution of
solar coronal element abundances over an active region lifetime. Magneto-convection drives the complexity of
magnetic fields that emerge above the photosphere. This complexity is dissipated, together with that of the overlying pre-existing fields, through dynamic events such as
flares. A period of stable "ordinary" coronal heating ensues, before the concentrated fields are dissipated through interactions with the surrounding environment. The
evolution of coronal abundances can be explained by the First Ionisation Potential (FIP) effect operating within this framework. We extend the discussion from
magnetic activity on timescales of active region lifetimes (months), to the
solar cycle (years), and
stellar evolution (eons). The broad picture shows intriguing similarities that may
prompt new investigations.
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All authors David H. Brooks, Deborah Baker, David M. Long. Paola Testa, Harry P. Warren
Instrumentation and Methods for Astrophysics · Cross-listed from cs.DC
astroCAMP: A Community Benchmark and Co-Design Framework for Sustainable SKA-Scale Radio Imaging
Denisa-Andreea Constantinescu, Rubén Rodríguez Álvarez, Jacques Morin et al. (+7 more)
The Square Kilometre Array (SKA) will operate one of the world's largest continuous scientific data systems, sustaining petascale imaging under strict power envelopes. Current
radio-interferometric pipelines typically achieve only 4-14% of hardware peak utilization due to
memory and I/O bottlenecks, incurring high energy, operational, and carbon costs, further compounded by the absence of standardised cross-layer metrics and fidelity tolerances for principled hardware–software co-design. We present astroCAMP, a reproducible benchmarking and co-design framework for SKA-scale imaging, contributing: (1) a unified metric suite spanning performance, utilisation,
memory/data-movement, sustainability, economics, and scientific fidelity; (2) standardised SKA-representative
datasets and
benchmark configurations for reproducible cross-platform evaluation; (3) a multi-objective co-design formulation linking quality constraints to time-, energy-, carbon-, and cost-to-solution; and (4) a design-space exploration workflow to derive Pareto-optimal operating regions. We evaluate WSClean+IDG on an AMD EPYC 9334 CPU and NVIDIA H100 GPU, revealing orchestration and synchronization bottlenecks despite efficient kernels, limited CPU strong scaling, and location-dependent carbon/cost efficiency. We illustrate astroCAMP for heterogeneous CPU–FPGA exploration and call on the SKA community to define quantifiable fidelity thresholds to accelerate principled optimisation for SKA-scale imaging.
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All authors Denisa-Andreea Constantinescu, Rubén Rodríguez Álvarez, Jacques Morin, Etienne Orliac, Mickaël Dardaillon, Sunrise Wang, Hugo Miomandre, Miguel Peón-Quirós, Jean-François Nezan, David Atienza
Instrumentation and Methods for Astrophysics
Tracing the Early Milky Way with Globular Clusters: The Diagnostic Power of Neutron-Capture Elements
J. Schiappacasse-Ulloa, L. Berni, S. Lucatello et al. (+3 more)
Globular clusters (GCs) are fundamental tracers of the early assembly of the Milky Way (MW). They formed in diverse environments – including both our
Galaxy and
dwarf galaxies – retaining chemical and dynamical signatures that encode their origins and the merger history of the
Galaxy. Although significant progress has been made in characterising GC chemistry, most studies have focused on light, $\alpha$-, and iron-peak elements. In contrast,
neutron-capture (n-capture) elements remain sparsely investigated across the GC system, despite their unique ability to trace nucleosynthetic channels and
star-formation timescales. A homogeneous and statistically robust mapping of n-process elements in a large sample of GCs would provide powerful constraints on their formation environments, chemical signatures of in situ and accreted systems, and refine our understanding of the early chemical
evolution of the MW
halo. Addressing this gap requires high-resolution, multiplexing, and blue-sensitive spectroscopy capable of accessing the full suite of n-capture diagnostics in several tens of
stars per GC.
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All authors J. Schiappacasse-Ulloa, L. Berni, S. Lucatello, L. Magrini, A. Bragaglia, R. E. Giribaldi
High Energy Astrophysical Phenomena
Identification of radio and gamma-ray pulsars in X-rays using data from the SRG/eROSITA all-sky survey
Yu.A. Shibanov, A.V. Karpova, D.A. Zyuzin et al. (+1 more)
Using the data from the all-sky survey in soft X-rays performed by the eROSITA
telescope onboard the Spectrum-Roentgen-Gamma observatory we identified known
radio and $\gamma$-ray
pulsars in the eastern half of the sky. As a result, new candidate counterparts were found for twelve
pulsars of different ages and types at a $\gtrsim$ 3$\sigma$ confidence level. A comparable number had been previously identified in the western half of the sky. In total, this represents about 12% of all known
pulsars already detected in X-rays. For the new counterparts, we provide estimates of their X-ray fluxes, preliminary characteristics of their X-ray spectra, and brief descriptions of the
pulsars' properties. In addition, in the eastern half of the sky eROSITA detected 55
pulsars previously identified in X-rays by other
telescopes.
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All authors Yu.A. Shibanov, A.V. Karpova, D.A. Zyuzin, M.R. Gilfanov
Solar and Stellar Astrophysics
Tales of stellar and binary co-evolution, told by stellar oscillations – Binary demographics and their impact on stellar mass, orbits, and age estimates in main-sequence and red-giant stars
Paul G. Beck
Red
giants are increasingly used as
stellar population tracers due to their well-understood
evolution and the availability of asteroseismic observables. However,
stellar binarity can alter observable properties and introduce strong biases. We aim to provide a holistic picture of the binary population and its
evolution in the red
giant phase by characterizing a sample of binaries hosting oscillating red
giants from a combination of extensive asteroseismic, spectroscopic, and astrometric surveys. We investigate the binary properties of evolved
stars in the APOKASC3 and APO-K2 catalogs, leveraging asteroseismic constraints and
Gaia DR3 non-single-
star solutions. We explore the mass distribution of red-
giant binary systems and analyze the
evolution of their binary fraction. For
stars with M$\leq$1.8M$_\odot$, we find binary fractions $\sim$31% and $\sim$41% for oscillating and non-oscillating
solar-like
stars on the main-sequence (MS). By the power excess ($\nu_\mathrm{max}$) as luminosity proxy, we detect a binary attrition of $\sim$69% and $\sim$81% on the low- and high-luminosity red-
giant branch (RGB) and an additional $\sim$38% to the red clump (RC), with respect to the MS. Binaries hosting RC and secondary clump
stars (2RC)
stars are largely depleted at $P_\mathrm{orb}\lesssim$500 and $\lesssim$200 days, respectively. Mass-dependent differences in binary fractions and orbital properties point to more substantial binary attrition for
stars with M $\leq$1.8 M$_\odot$. The distinct mass distributions and the depletion of short-period binaries during the red-
giant phase underscore the impact of
stellar expansion and binary interactions on
stellar evolution. RC systems with $P_\mathrm{orb}\lesssim$800 to 1,000 days are likely shaped by past interactions, such as mass transfer or loss, which can lead to significantly biased age estimates if not accounted for.
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High Energy Astrophysical Phenomena
Leptonic and hadronic models of high-energy nebula around V4641 Sgr
Maksim Kleimenov, Andrii Neronov, Foteini Oikonomou et al. (+1 more)
A prominent, 200-pc-scale high-energy nebula surrounding the microquasar V4641 Sgr is the brightest known gamma-ray source in the Southern sky at $E > 100\,\mathrm{TeV}$. In this paper, we develop self-consistent leptonic, hadronic, and leptohadronic models that reproduce both the observed spectrum and morphology of the source. Purely leptonic models are energetically more favorable yet they require rather specific morphological assumptions. The gamma-ray morphology of the source can be better explained within a hadronic scenario based on the identification of cold gas structures spatially correlated with the observed gamma-ray emission. However, a purely hadronic model for the source emission requires a substantial energy reservoir in
protons and fails to reproduce the extended x-ray emission recently detected by XRISM. We show that emission including a combination of leptonic and hadronic components can reproduce both the spectral and morphological properties of the source. We provide predictions for the x-ray and
neutrino spectra of the nebula that can discriminate the hadronic and leptonic contributions to the overall source signal.
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All authors Maksim Kleimenov, Andrii Neronov, Foteini Oikonomou, Dmitri Semikoz
Cosmology and Nongalactic Astrophysics
Fermionic versus Bosonic Dark Matter in Neutron Stars: A Bayesian Study with Multi-Density Constraints
Payaswinee Arvikar, Sakshi Gautam, Anagh Venneti et al. (+1 more)
We perform a comparative
Bayesian analysis of fermionic and bosonic dark matter admixed
neutron stars (DMANS) by incorporating a comprehensive set of theoretical, experimental, and astrophysical constraints. The hadronic matter equation of state (EoS) is modeled using a relativistic mean-field approach, constrained by
chiral effective field theory ($\chi$EFT) calculations at low densities, finite
nuclei and heavy-ion collision data at intermediate densities, and
neutron star (NS) observations at high densities. For the dark sector, we consider fermionic dark matter (FDM) interacting via a dark vector
meson, and two bosonic dark matter models (BDM1 and BDM2) characterized by self-interacting scalar fields.
Bayesian inference is employed to constrain the model parameters, including the dark matter mass, coupling strength, and dark matter fraction within NSs. Our analysis finds that all models yield consistent
nuclear matter parameters, allowing a small dark matter fraction under 10%. The presence of dark matter slightly softens the EoS, leading to a modest reduction in NS mass, radius, and
tidal deformability, though all models remain compatible with NICER and GW170817 observations. The log-evidence and likelihood analyses reveal no statistical preference among the FDM and BDM models, indicating that current astrophysical data cannot decisively distinguish between fermionic and bosonic dark matter scenarios. This study provides a unified statistical framework to constrain dark matter properties using NS observables.
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All authors Payaswinee Arvikar, Sakshi Gautam, Anagh Venneti, Sarmistha Banik
High Energy Astrophysical Phenomena
Unveiling the X-ray Secrets of Fermi-detected Narrow-Line Seyfert 1 Galaxies with XMM-Newton Observations
Suvas Chandra Chaudhary, Raj Prince, Brian van Soelen et al. (+1 more)
In the innermost regions of active
galactic nuclei, where the
accretion disk, corona, and jet processes are closely coupled, X-ray observations offer a direct probe to study the physics of disk-jet coupling and the mechanisms driving relativistic
outflows. We present a comprehensive analysis of the X-ray timing and spectral variability of 16 Narrow Line Seyfert 1
galaxies detected by
Fermi-LAT, based on 29 epochs of XMM-Newton observations. A moderate intraday flux variability is observed throughout the sample, with fractional variability ranging from 5 to 16%. The temporal study of 1H\,0323+342 reveals a distinctive turnover timescale in structure functions, along with notable variations in flux and power spectral density slopes. The hardness ratio in some epochs demonstrates a clear trend of softer-when-brighter. The X-ray spectra of 1H 0323+342, PMN J0948+0022, RGB J1644+263, PKS 1502+036, and J1246+0238 are well fitted by a power-law + blackbody model, suggesting a bright disk along with a jet, and J1222+0413 is fitted by broken power-law, while the remaining sources are well fitted by a power-law model revealing the non-thermal domination. The X-ray luminosity exhibits a strong correlation with $\gamma$-ray and disk luminosity, and a strong correlation with the jet power, suggesting a close coupling of disk and jet. Additionally, we have found an anti-correlation between the X-ray spectral index and the X-ray luminosity, as well as with the FWHM of H$\beta$ line, indicating a complex interaction between the central engine, jet activity, and the
accretion disk in these sources.
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All authors Suvas Chandra Chaudhary, Raj Prince, Brian van Soelen, I.P. van der Westhuizen
Solar and Stellar Astrophysics
Tides in Massive Binaries: Numerical Solutions and Semi-Analytical Comparisons
Meng Sun, Hongbo Xia, Seth Gossage et al. (+5 more)
We present a systematic comparison between the
tidal secular
evolution timescales predicted by the direct numerical method and those given by the commonly used semi-analytic prescriptions implemented in 1-D hydrostatic binary
evolution codes. Our study focuses on binary systems with intermediate- to high-mass primaries ($M_1 = 5$-$50\,M_\odot$), companion masses between $1.4\,M_\odot$ and $10\,M_\odot$, and orbital periods ranging from 0.5 to 50 days. Before mass transfer, both approaches predict synchronization and orbital decay timescales that agree within $\sim$2 orders of magnitude and typically exceed the
stellar main sequence lifetime, implying negligible
tidal impact on secular orbital
evolution. However, the implied dissipation channels differ, and the differences become more pronounced once mass transfer begins. To test the theoretical predictions against observations, we apply both approaches to the well-characterized PSR J0045–7319 system, which has an orbital decay timescale of 0.5 Myr. The numerical solution reveals strong resonances with internal
gravity waves, bringing the predicted orbital period change rate close to the observed value. In contrast, the semi-analytic prescriptions predict orbital decay timescales longer than the Hubble time. These results suggest that for population studies, modestly calibrated parameterized equations may suffice, but for individual systems, reliable interpretation requires direct numerical approaches.
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All authors Meng Sun, Hongbo Xia, Seth Gossage, Vicky Kalogera, Jifeng Liu, Kyle Akira Rocha, Richard H. D. Townsend, Emmanouil Zapartas
Cosmology and Nongalactic Astrophysics
The Serendipitous Axiodilaton: A Self-Consistent Recombination-Era Solution to the Hubble Tension
Adam Smith, Maria Mylova, Carsten van de Bruck et al. (+2 more)
Axio-dilaton cosmology provides a minimal
benchmark model for both Dark Matter (DM) and Dark Energy (DE) that is well motivated by fundamental physics. The
axion and dilaton arise as pseudo-Goldstone modes of
symmetries that predict particle masses depend on the dilaton, and therefore to evolve cosmologically, leading to correlated modifications of recombination physics, the sound horizon, and late-time expansion and growth histories. We confront this model with Planck 2018 temperature, polarisation, and
lensing data, SPT-3G high-$\ell$ measurements, DESI DR2 BAO, and Pantheon$+$
supernovae, assuming that the
axion makes up all of the dark matter and that the dilaton plays the role of a dark energy field. We find that it fits the data somewhat better than $\Lambda$CDM cosmology, with the $\chi^2$ lowered by $\simeq 7$ for three additional parameters, and significantly raises the inferred Hubble constant to $H_0 \simeq 69.2\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$, reducing the Hubble tension to $\lesssim 3\sigma$ and thereby allowing a joint fit of CMB and SH0ES data. The model fits this enlarged data set as well as the $w_0w_a$ model with an electron mass modified by hand at recombination, though it does so with calculable dynamics. Axio-dilaton self-interactions robustly fake a phantom equation of state in DESI measurements. There is a sting: cosmology prefers dilaton-matter couplings $|\mathbf{g}|\sim 10^{-2}$-$10^{-1}$, which are large enough to have been detected in
solar-system tests of General Relativity. These results show how axio-dilatons can provide a viable cosmology preferred by current data at surprisingly large couplings, within a framework that links dark energy, dark matter, and time-dependent particle masses in a coherent way. They suggest both new observable signals and new theoretical directions, aimed at resolving the apparent inconsistency with non-cosmological observations.
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All authors Adam Smith, Maria Mylova, Carsten van de Bruck, C.P. Burgess, Eleonora Di Valentino
Earth and Planetary Astrophysics
The Flying Saucer edge-on disc's Near Infrared silhouette revealed by the JWST JEDIce program
Emmanuel Dartois, Jennifer A. Noble, Jennifer B. Bergner et al. (+17 more)
Edge-on discs offer a unique opportunity to probe radial and vertical
dust and gas distributions in the protoplanetary phase. This study aims to investigate the distribution of micron-sized
dust particles in the Flying Saucer (BKLT J162813-243139) in Rho Ophiuchi, leveraging the unique observational conditions of a bright infrared background that enables the edge-on disc to be seen in both silhouette and scattered light at certain, specific wavelengths. As part of the JWST Edge-on Disc Ice program ('JEDIce'), we use NIRSpec IFU observations of the Flying Saucer, serendipitously observed against a PAH-emitting background, to constrain the
dust distribution and grain sizes through radiative transfer modelling. Observation of the Flying Saucer in silhouette at 3.29 microns reveals that the midplane radial extent of small
dust grains is ~235 au, larger than the large-grain disc extent previously determined to be 190 au from millimetre data. The scattered light observed in emission probes micron sized icy grains at large vertical distances above the midplane. The vertical extent of the disc silhouette is similar at visible, near-IR, and mid-IR wavelengths, corroborating the conclusion that
dust settling is inefficient for grains as large as tens of microns, vertically and radially.
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All authors Emmanuel Dartois, Jennifer A. Noble, Jennifer B. Bergner, Klaus M. Pontoppidan, Korash Assani, Daniel Harsono, Melissa K. McClure, Julia C. Santos, Will E. Thompson, Lukas Welzel, Nicole Arulanantham, Alice S. Booth, Maria N. Drozdovskaya, Zhi-Yun Li, Jie Ma, Laurine Martinien, François Ménard, Karin Oberg, Karl Stapelfeldt, Yao-Lun Yang
High Energy Astrophysical Phenomena
Multi-Method Timing of Transient Radio Pulsars with the GBT350 and GBNCC Surveys
E. F. Lewis, M. A. McLaughlin, J. K. Swiggum et al. (+23 more)
We present the timing solutions for three
radio pulsars discovered with the Green Bank North Celestial Cap (GBNCC) and 350-MHz Green Bank
Telescope drift-scan surveys. These
pulsars were initially discovered through their single-pulse emission and therefore designated as rotating
radio transients (RRATs). Follow-up timing campaigns yielded a number of higher signal-to-noise summed pulse profiles for each
pulsar, allowing us to obtain timing solutions both through single pulses as well as the standard method of time-integrating the
pulsar's emission. We find that the two methods return timing parameters which are usually in agreement within two standard deviations, and have similar sized error bars. The single-pulse timing solutions have significantly higher RMS errors and reduced chi-squared values, likely due to pulse jitter. The distribution of wait times between detected single pulses indicates a significant amount of pulse clustering in time on short timescales from all three sources. For all sources, the presence of low-level emission outside of the sparse bright pulses and lack of
giant pulses is more reminiscent of highly nulling canonical
radio pulsars than extremely transient RRATs, highlighting the diversity of emission behavior observed from sources published as RRATs.
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All authors E. F. Lewis, M. A. McLaughlin, J. K. Swiggum, H. Blumer, J. Boyles, P. Chawla, T. Dolch, J. W. T. Hessels, D. L. Kaplan, C. Karako-Argaman, V. Kaspi, V. Kondratiev, L. Levin, R. S. Lynch, J. G. Martinez, A. E. McEwen, R. Miller, E. Parent, S. M. Ransom, M. S. E. Roberts, A. Rowe, R. Spiewak, I. H. Stairs, K. Stovall, J. Thorley, J. van Leeuwen