Abstracts of Interest

Selected by: Robert Christian Koenig


Abstract: 2405.14826
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Title:New limits on neutrino decay from high-energy astrophysical neutrinos

Authors:Victor B. Valera, Damiano F. G. Fiorillo, Ivan Esteban, Mauricio Bustamante
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Abstract:Since neutrinos have mass differences, they could decay into one another. But their lifetimes are likely long, even when shortened by new physics, so decay likely impacts neutrinos only during long trips. This makes high-energy astrophysical neutrinos, traveling for up to billions of light-years, sensitive probes of decay. However, their sensitivity must be tempered by reality. We derive from them thorough bounds on the neutrino lifetimes accounting for critical astrophysical unknowns and the nuances of neutrino detection. Using the diffuse neutrino flux, we disfavor lifetimes $\tau \lesssim 20$-450 s $(m/{\rm eV})$, based on present IceCube data, and forecast factor-of-10 improvements by upcoming detectors. Using, for the first time, neutrinos from the active galaxy NGC 1068, extant unknowns preclude placing lifetime bounds today, but upcoming detectors could disfavor $\tau \sim 100$-5000 s $(m/{\rm eV})$.

Comments: 20 pages, 6 figures, 2 tables, plus appendices


Abstract: 2405.14764
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Title:Multi-Messenger Emission Characteristics of Blazars

Authors:Ronald Gamble Jr, Jordan Forman, Amethyst Barnes, Gokul Srinivasaragavan, Isiah Holt, Marvin Jones Jr
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Abstract:Multi-Messenger observations and theory of astrophysical objects is fast becoming a critical research area in the astrophysics scientific community. In particular, point-like objects like that of BL Lac, flat spectrum radio quasars (FSRQ), and blazar candidates of uncertain type (BCU) are of distinct interest among those who look at the synchrotron, Compton, neutrino, and cosmic ray emissions sourced from compact objects. Notably, there is also much interest in the correlation between multi-frequency observations of blazars and neutrino surveys on source demographics. In this review we look at such multi-frequency and multi-physics correlations of the radio, X-ray, and $\gamma$-ray fluxes of different classes of blazars from a collection of survey catalogues. This multi-physics survey of blazars shows that there are characteristic cross-correlations in the spectra of blazars when considering their multi-frequency and multi-messenger emission. Accompanying this will be a review of cosmic ray and neutrino emissions from blazars and their characteristics.

Comments: 13 pages, 4 figures (reviewed, Frontiers: Astronomy & Space Sciences, The Dynamic Universe: Realizing the Potential of Time Domain and Multimessenger Astrophysics)


Abstract: 2405.14483
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Title:On resonance coupling in spiral arms: Patterns for flat rotation curve

Authors:Alexander A. Marchuk
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Abstract:To address questions about the physical nature and origin of spiral arms in galaxies, it is necessary to measure their dynamical properties, such as the angular speed $\Omega_p$ or the corotation radius. Observations suggest that galaxies may contain several independent spiral patterns simultaneously. It was shown that so-called non-linear resonance coupling plays an important role in such systems. We aim to identify cases of independent spiral patterns for galaxies with a flat rotation curve, and to investigate what relative pattern velocities $\Omega^{out}_{p}/\Omega^{in}_{p}$ they could have in principle for all possible cases of coupling between the main resonances. We solve equations for the main resonance positions (1:1, 2:1, 4:1) and estimate the ratio $\varpi$ of the corotation radii for two subsequent patterns. For six close galaxies with flat rotation curves, we collect the measurements of the corotation radii in the literature, using at least three different methods in each case for credibility, and measure the $\varpi$ ratio. We find $\varpi$ ratios for all possible cases for the main resonances. For three cases we get $\varpi>3$, meaning that it will be difficult to fit two or even more spiral patterns in the disc. These ratios have been used to derive the wind up time for spirals, estimated to be several galactic rotations. We find that three pairs of coupling cases, including vastly acknowledged in galaxies $OLR_{in}=CR_{out} \& CR_{in}=IUHR_{out}$, have very close $\varpi$ ratios, hence should be found simultaneously, as observed. We find strongly confirmed apparent resonance coupling for six galaxies, and show that the observed $\varpi$ is in agreement with theory. In two of them we identify a previously unreported form of simultaneous coupling, namely $OLR_{in}=OUHR_{out} \& OUHR_{in}=CR_{out}$, which was also predicted from the proximity of $\varpi$.

Comments: Accepted for publication in A&A Letters


Abstract: 2405.14357
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Title:Cosmological Constraints on Long Gamma-Ray Bursts from Fermi observations

Authors:Huifeng Wang, Nan Liang
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Abstract:In this paper, we compile a \emph{Fermi} sample of the \emph{long} GRBs from \emph{Fermi} observations with 15 years of the Fermi-GBM catalogue with identified redshift, in which the GOLD sample contains 123 long GRBs at $z\le5.6$ and the FULL sample contains 151 long GRBs with redshifts at $z\le8.2$. The Amati relation (the $E_{\rm p,i}$-$E_{\rm iso}$ correlation) are calibrated at $z<1.4$ by a Gaussian Process from the latest observational Hubble data (OHD) with the cosmic chronometers method to obtain GRBs at high-redshift $z\ge1.4$ which can be used to constrain cosmological models via the Markov chain Monte Carlo (MCMC) method. With the cosmology-independent GRBs with the GOLD sample at $z\ge1.4$ and the Pantheon sample of type Ia supernovae (SNe Ia) at $0.01<z\leq2.3$, we obtain $\Omega_{\rm m} = 0.354\pm0.018, H_0 = 73.05\pm0.002$ for the flat $\Lambda$CDM model; $w_0 = -1.22^{+0.18}_{-0.15}$ for the flat $w$CDM model; and $w_{a} = -1.12^{+0.45}_{-0.83}$ for the flat Chevallier-Polarski-Linder model at the 1$\sigma$ confidence level. Our results with the GOLD and FULL sample are almost identical, which are more stringent than the previous results with GRBs.

Comments: 14 pages, 10 figures, 4 Tables


Abstract: 2405.13630
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Title:STONKS: Quasi-real time XMM-Newton transient detection system

Authors:E. Quintin, N.A. Webb, I. Georgantopoulos, M. Gupta, E. Kammoun, L. Michel, A. Schwope, H. Tranin, I. Traulsen
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Abstract:Over recent decades, astronomy has entered the era of massive data and real-time surveys. This is improving the study of transient objects - although they still contain some of the most poorly understood phenomena in astrophysics, as it is inherently more difficult to obtain data on them. In order to help detect these objects in their brightest state, we have built a quasi-real time transient detection system for the XMM-Newton pipeline: the Search for Transient Objects in New detections using Known Sources (STONKS) pipeline. STONKS detects long-term X-ray transients by automatically comparing new XMM-Newton detections to any available archival X-ray data at this position, sending out an alert if the amplitude of variability between observations is over 5. This required an initial careful cross-correlation and flux calibration of various X-ray catalogs from different observatories (XMM-Newton, Chandra, Swift, ROSAT, and eROSITA). We also systematically computed the XMM-Newton upper limits at the position of any X-ray source covered by the XMM-Newton observational footprint, even without any XMM-Newton counterpart. The behavior of STONKS was then tested on all 483 observations performed with imaging mode in 2021. Over the 2021 testing run, STONKS provided $0.7^{+0.7}_{-0.5}$ alerts per day, about 80% of them being serendipitous. STONKS also detected targeted tidal disruption events, ensuring its ability to detect other serendipitous events. As a byproduct of our method, the archival multi-instrument catalog contains about one million X-ray sources, with 15% of them involving several catalogs and 60% of them having XMM-Newton upper limits. STONKS demonstrates a great potential for revealing future serendipitous transient X-ray sources, providing the community with the ability to follow-up on these objects a few days after their detection.

Comments: 30 pages, 30 figures, accepted in A&A


Abstract: 2405.13491
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Title:Euclid. I. Overview of the Euclid mission

Authors:Euclid Collaboration: Y. Mellier (1 and 2), Abdurro'uf (3), J. A. Acevedo Barroso (4), A. Achúcarro (5 and 6), J. Adamek (7), R. Adam (8), G. E. Addison (3), N. Aghanim (9), M. Aguena (10), V. Ajani (11 and 12 and 13), Y. Akrami (14 and 15), A. Al-Bahlawan (16), A. Alavi (17), I. S. Albuquerque (18), G. Alestas (14), G. Alguero (19), A. Allaoui (20), S. W. Allen (21 and 22 and 23), V. Allevato (24), A. V. Alonso-Tetilla (25), B. Altieri (26), A. Alvarez-Candal (27 and 28), A. Amara (29), L. Amendola (30), J. Amiaux (11), I. T. Andika (31 and 32), S. Andreon (33), A. Andrews (34), G. Angora (24 and 35), R. E. Angulo (36 and 37), F. Annibali (34), A. Anselmi (38), S. Anselmi (39 and 40 and 41), S. Arcari (35 and 42), M. Archidiacono (43 and 44), G. Aricò (7), M. Arnaud (45 and 46), S. Arnouts (20), M. Asgari (47), J. Asorey (48), L. Atayde (18), H. Atek (2), F. Atrio-Barandela (49), M. Aubert (50 and 51), E. Aubourg (10 and 45), T. Auphan (52), N. Auricchio (34), B. Aussel (53), H. Aussel (11), P. P. Avelino (54 and 55), A. Avgoustidis (56), S. Avila (57), S. Awan (16), R. Azzollini (16), C. Baccigalupi (58 and 59 and 60 and 61), E. Bachelet (62), D. Bacon (63), M. Baes (64), M. B. Bagley (65), B. Bahr-Kalus (51 and 66), A. Balaguera-Antolinez (67 and 68), E. Balbinot (69 and 70), M. Balcells (67 and 68 and 71), M. Baldi (72 and 34 and 73), I. Baldry (74), A. Balestra (75), M. Ballardini (35 and 34 and 42), O. Ballester (57), M. Balogh (76 and 77), E. Bañados (78), R. Barbier (51), S. Bardelli (34), T. Barreiro (18 and 79), J.-C. Barriere (80), B. J. Barros (18), A. Barthelemy (81), N. Bartolo (40 and 39 and 75), A. Basset (82), P. Battaglia (34), A. J. Battisti (83 and 84 and 85), C. M. Baugh (86), L. Baumont (11), L. Bazzanini (35 and 34), J.-P. Beaulieu (1 and 87), V. Beckmann (88), A. N. Belikov (69 and 89), J. Bel (90), F. Bellagamba (72 and 34), M. Bella (91), E. Bellini (61 and 58 and 59 and 60), K. Benabed (2), R. Bender (92 and 81), G. Benevento (93), C. L. Bennett (3), K. Benson (16), P. Bergamini (43 and 34), J. R. Bermejo-Climent (67 and 68), F. Bernardeau (94 and 2), D. Bertacca et al. (1011 additional authors not shown)
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Abstract:The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main ingredients, dark matter and dark energy, remains unknown. Euclid is a medium-class mission in the Cosmic Vision 2015-2025 programme of the European Space Agency (ESA) that will provide high-resolution optical imaging, as well as near-infrared imaging and spectroscopy, over about 14,000 deg^2 of extragalactic sky. In addition to accurate weak lensing and clustering measurements that probe structure formation over half of the age of the Universe, its primary probes for cosmology, these exquisite data will enable a wide range of science. This paper provides a high-level overview of the mission, summarising the survey characteristics, the various data-processing steps, and data products. We also highlight the main science objectives and expected performance.

Comments: Paper submitted as part of the A&A special issue`Euclid on Sky'


Abstract: 2405.12918
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Title:Impact of inhomogeneous diffusion on secondary cosmic ray and antiproton local spectra

Authors:Álvaro Tovar-Pardo, Pedro De La Torre Luque, Miguel Ángel Sánchez-Conde
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Abstract:Recent $\gamma$-ray and neutrino observations seem to favor the consideration of non-uniform diffusion of cosmic rays (CRs) throughout the Galaxy. In this study, we investigate the consequences of spatially-dependent inhomogeneous propagation of CRs on the fluxes of secondary CRs and antiprotons detected at Earth. A comparison is made among different scenarios in search of potential features that may guide us toward favoring one over another in the near future. We also examine both the influence of inhomogeneous propagation in the production of secondary CRs from interactions with the gas, and the effects of this scenario on the local fluxes of antiprotons and light antinuclei produced as final products of dark matter annihilation. Our results indicate that the consideration of an inhomogeneous diffusion model could improve the compatibility of the predicted local antiproton flux with that of B, Be and Li, assuming only secondary origin of these particles. In addition, our model predicts a slightly harder local antiproton spectrum, making it more compatible with the high energy measurements of AMS-02. Finally, no significant changes are expected in the predicted local flux of antiprotons and antinuclei produced from dark matter among the different considered propagation scenarios.

Comments: 19 pages, 6 figures in the main text and 3 figures in appendices, 1 table, 2 appendices; based on MSc Thesis of Álvaro Tovar-Pardo. Comments are welcome


Abstract: 2405.12665
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Title:Age of massive galaxies at redshift 8

Authors:M. Lopez-Corredoira, F. Melia, J.-J. Wei, C.-Y. Gao
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Abstract:Recent James Webb Space Telescope (JWST) data analyses have shown that massive red galaxies existed at redshifts $z>6$, a discovery that is difficult to understand in the context of standard cosmology ($\Lambda $CDM). Here we analyze these observations more deeply by fitting a stellar population model to the optical and near-infrared photometric data. These fits include a main stellar population in addition to a residual younger population and with the same extinction for both (a lower extinction for the younger population is unphysical). Extra stellar populations or the inclusion of an AGN component do not significantly improve the fits. These galaxies are being viewed at very high redshifts, with an average $\langle z\rangle \approx 8.2$, when the $\Lambda$CDM Universe was only $\approx 600$ Myr old. This result conflicts with the inferred ages of these galaxies, however, which were on average between 0.9 and 2.4 Gyr old within 95% CL. Given the sequence of star formation and galaxy assembly in the standard model, these galaxies should instead be even younger than 290 Myr on average, for which our analysis assigns a probability of only $<3\times 10^{-4}$ ($\gtrsim 3.6\sigma $ tension). This outcome may indicate the need to consider non-standard cosmologies. Nevertheless, our conclusions result from several approximations in stellar astrophysics and extinction, so they should be taken with a grain of salt. Further research is necessary to corroborate the possible existence of galaxies older than the $\Lambda $CDM universe at their observed redshifts.

Comments: 16 pages, 8 figures, accepted to be published in ApJ


Abstract: 2405.12216
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Title:Radiative transfer of 21-cm line through ionised cavities in an expanding universe

Authors:Kinwah Wu, Qin Han, Jennifer Y. H. Chan
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Abstract:The optical depth parameterisation is typically used to study the 21-cm signals associated with the properties of the neutral hydrogen (HI) gas and the ionisation morphology during the Epoch of Reionisation (EoR), without solving the radiative transfer equation. To assess the uncertainties resulting from this simplification, we conduct explicit radiative transfer calculations using the cosmological 21-cm radiative transfer (C21LRT) code and examine the imprints of ionisation structures on the 21-cm spectrum. We consider a globally averaged reionisation history and implement fully ionised cavities (HII bubbles) of diameters $d$ ranging from 0.01 Mpc to 10 Mpc at epochs within the emission and the absorption regimes of the 21-cm global signal. The single-ray C21LRT calculations show that the shape of the imprinted spectral features are primarily determined by $d$ and the 21-cm line profile, which is parametrised by the turbulent velocity of the HI gas. It reveals the spectral features tied to the transition from ionised to neutral regions that calculations based on the optical depth parametrisation were unable to capture. We also present analytical approximations of the calculated spectral features of the HII bubbles. The multiple-ray calculations show that the apparent shape of a HII bubble (of $d=5$ Mpc at $z=8$), because of the finite speed of light, differs depending on whether the bubble's ionisation front is stationary or expanding. Our study shows the necessity of properly accounting for the effects of line-continuum interaction, line broadening and cosmological expansion to correctly predict the EoR 21-cm signals.

Comments: 15 pages, 11 figures, 1 table


Abstract: 2405.12212
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Title:Forced Measurement of Astronomical Sources at Low Signal to Noise

Authors:Anirban Dutta, John R. Peterson, Glenn Sembroski
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Abstract:We propose a modified moment matching algorithm to avoid catastrophic failures for sources with a low signal to noise ratio (SNR). The proposed modifications include a method to eliminate non-physical negative pixel values and a forced single iteration with an initial guess derived from co-add measurements when iterative methods are unstable. We correct for all biases in measurements introduced by the method. We find that the proposed modifications allow the algorithm to avoid catastrophic failures in nearly 100\% of the cases, especially at low signal to noise ratio. Additionally, with a reasonable guess from co-add measurements, the algorithm measures the flux, centroid, size, shape and ellipticity with bias statistically consistent with zero. We show the proposed method allows us to measure sources seven times fainter than traditional methods when applied to images obtained from WIYN-ODI. We also present a scheme to find uncertainties in measurements when using the new method to measure astronomical sources.



Abstract: 2405.12146
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Title:Cosmic Ray Diffusion in the Turbulent Interstellar Medium: Effects of Mirror Diffusion and Pitch Angle Scattering

Authors:Lucas Barreto-Mota, Elisabete M. de Gouveia Dal Pino, Siyao Xu, Alexandre Lazarian
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Abstract:Cosmic rays (CRs) interact with turbulent magnetic fields in the intestellar medium, generating nonthermal emission. After many decades of studies, the theoretical understanding of their diffusion in the ISM continues to pose a challenge. This study numerically explores a recent prediction termed "mirror diffusion" and its synergy with traditional diffusion mechanism based on gyroresonant scattering. Our study combines 3D MHD simulations of star-forming regions with test particle simulations to analyze CR diffusion. We demonstrate the significance of mirror diffusion in CR diffusion parallel to the magnetic field, when the mirroring condition is satisfied. Our results support the theoretical expectation that the resulting particle propagation arising from mirror diffusion in combination with much faster diffusion induced by gyroresonant scattering resembles a Levy-flight-like propagation. Our study highlights the necessity to reevaluate the diffusion coefficients traditionally adopeted in the ISM based on gyroresonant scattering alone. For instance, our simulations imply a diffusion coefficient $\sim10^{27}cm^2/s$ for particles with a few hundred TeV within regions spanning a few parsecs around the source. This estimate is in agreement with gamma-ray observations, which shows the relevance of our results for understanding of diffuse gamma-ray emission in star-forming regions.



Abstract: 2405.12004
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Title:Binary neutron star mergers as the source of the highest energy cosmic rays

Authors:Glennys R. Farrar
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Abstract:We propose that ultrahigh energy cosmic rays are produced in binary neutron star mergers. Interpreting the highest energy events as r-process nuclei eliminates the need for exotic sources, while the observed near-universal maximum rigidity of ultrahigh energy sources can be understood as due to the uniformity of jets generated by the gravitationally-driven dynamo, given the narrow range of total binary neutron star masses. We discuss evidence for this scenario, and its prediction of coincidences between neutrinos above 10 PeV and gravitational waves.



Abstract: 2405.11104
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Title:H.E.S.S.: The High Energy Stereoscopic System

Authors:Gerd Pühlhofer, Fabian Leuschner, Heiko Salzmann
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Abstract:The High Energy Stereoscopic System H.E.S.S. is an array of Cherenkov Telescopes located in the Khomas Highlands in Namibia. H.E.S.S. started operations in 2003 and has been operated very successfully since then. With its location in the Southern hemisphere, the system provides a privileged view of the Milky Way and the Galactic center region. With H.E.S.S., a large variety of new TeV emitters has been discovered, both in our Galaxy and in extragalactic space. We provide a description of the individual telescopes and of the system as a whole, and review the scientific highlights that have been achieved with the instrument.

Comments: 38 pages, 4 figures. Appeared in the "Handbook of X-ray and Gamma-ray Astrophysics" by Springer (Eds. C. Bambi and A. Santangelo)


Abstract: 2405.10730
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Title:Passage of a Gamma-Ray Burst Through a Molecular Cloud: Cloud Ionization Structure

Authors:Aleksandr Nesterenok
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Abstract:The model is constructed of the propagation of gamma-ray burst radiation through a dense molecular cloud. The main processes of the interaction of the radiation with the interstellar gas are taken into account in the simulations: the ionization of H and He atoms, the ionization of metal ions and the emission of Auger electrons, the photoionization and the photodissociation of H$_2$ molecules, the absorption of ultraviolet radiation via Lyman and Werner band transitions of H$_2$, the thermal sublimation of dust grains. The ionization of metal ions by X-ray radiation determines the gas ionization fraction in the cloud region, where the gas is predominantly neutral. The ionization of inner electron shells of ions is accompanied by the emission of Auger electrons, giving rise to metal ions in a high ionization state. In particular, the column densities of Mg, Si, Fe in the ionization states I$-$IV are much lower than the column densities of these ions in the ionization state V and higher. The photoionization of metal ions by ultraviolet radiation takes place at distances smaller than the dust-destruction radius and only for neutral atoms with an ionization threshold below 13.6 eV. The simulations have confirmed the previously made suggestion that the ionization of He atoms plays an important role in the absorption of radiation in the X-ray wavelength range. For a low metallicity, $\rm [M/H] \leq -1$, the role of He atoms is dominant.

Comments: 22 pages, 8 figures, translation from Russian by author


Abstract: 2405.10369
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Title:Reinforcement learning

Authors:Sarod Yatawatta
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Abstract:Observing celestial objects and advancing our scientific knowledge about them involves tedious planning, scheduling, data collection and data post-processing. Many of these operational aspects of astronomy are guided and executed by expert astronomers. Reinforcement learning is a mechanism where we (as humans and astronomers) can teach agents of artificial intelligence to perform some of these tedious tasks. In this paper, we will present a state of the art overview of reinforcement learning and how it can benefit astronomy.

Comments: To appear, Astronomy & Computing


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