Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1710.07249

Inferences on Mass Composition and Tests of Hadronic Interactions from 0.3 to 100 EeV using the water-Cherenkov Detectors of the Pierre Auger Observatory

The Pierre Auger Collaboration·A. Aab·P. Abreu·M. Aglietta·I. Al Samarai·I. F. M. Albuquerque·I. Allekotte·A. Almela·J. Alvarez Castillo·J. Alvarez-Muñiz·G. A. Anastasi·L. Anchordoqui·B. Andrada·S. Andringa·C. Aramo·F. Arqueros·N. Arsene·H. Asorey·P. Assis·J. Aublin·G. Avila·A. M. Badescu·A. Balaceanu·F. Barbato·R. J. Barreira Luz·J. J. Beatty·K. H. Becker·J. A. Bellido·C. Berat·M. E. Bertaina·X. Bertou·P. L. Biermann·J. Biteau·S. G. Blaess·A. Blanco·J. Blazek·C. Bleve·M. Boháčová·D. Boncioli·C. Bonifazi·N. Borodai·A. M. Botti·J. Brack·I. Brancus·T. Bretz·A. Bridgeman·F. L. Briechle·P. Buchholz·A. Bueno·S. Buitink·M. Buscemi·K. S. Caballero-Mora·L. Caccianiga·A. Cancio·F. Canfora·L. Caramete·R. Caruso·A. Castellina·F. Catalani·G. Cataldi·L. Cazon·A. G. Chavez·J. A. Chinellato·J. Chudoba·R. W. Clay·A. Cobos·R. Colalillo·A. Coleman·L. Collica·M. R. Coluccia·R. Conceição·G. Consolati·F. Contreras·M. J. Cooper·S. Coutu·C. E. Covault·J. Cronin·S. D'Amico·B. Daniel·S. Dasso·K. Daumiller·B. R. Dawson·R. M. de Almeida·S. J. de Jong·G. De Mauro·J. R. T. de Mello Neto·I. De Mitri·J. de Oliveira·V. de Souza·J. Debatin·O. Deligny·M. L. Díaz Castro·F. Diogo·C. Dobrigkeit·J. C. D'Olivo·Q. Dorosti·R. C. dos Anjos·M. T. Dova·A. Dundovic·J. Ebr
View original source ↗Read source document ↗Export metadata ↓

Abstract

We present a new method for probing the hadronic interaction models at ultra-high energy and extracting details about mass composition. This is done using the time profiles of the signals recorded with the water-Cherenkov detectors of the Pierre Auger Observatory. The profiles arise from a mix of the muon and electromagnetic components of air-showers. Using the risetimes of the recorded signals we define a new parameter, which we use to compare our observations with predictions from simulations. We find, firstly, inconsistencies between our data and predictions over a greater energy range and with substantially more events than in previous studies. Secondly, by calibrating the new parameter with fluorescence measurements from observations made at the Auger Observatory, we can infer the depth of shower maximum for a sample of over 81,000 events extending from 0.3 EeV to over 100 EeV. Above 30 EeV, the sample is nearly fourteen times larger than currently available from fluorescence measurements and extending the covered energy range by half a decade. The energy dependence of the average depth of shower maximum is compared to simulations and interpreted in terms of the mean of the logarithmic mass. We find good agreement with previous work and extend the measurement of the mean depth of shower maximum to greater energies than before, reducing significantly the statistical uncertainty associated with the inferences about mass composition.

Explore related subjects

astro-ph.HE

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

The Pierre Auger Collaboration, A. Aab, P. Abreu, M. Aglietta, I. Al Samarai, I. F. M. Albuquerque, I. Allekotte, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, G. A. Anastasi, L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, F. Arqueros, N. Arsene, H. Asorey, P. Assis, J. Aublin, G. Avila, A. M. Badescu, A. Balaceanu, F. Barbato, R. J. Barreira Luz, J. J. Beatty, K. H. Becker, J. A. Bellido, C. Berat, M. E. Bertaina, X. Bertou, P. L. Biermann, J. Biteau, S. G. Blaess, A. Blanco, J. Blazek, C. Bleve, M. Boháčová, D. Boncioli, C. Bonifazi, N. Borodai, A. M. Botti, J. Brack, I. Brancus, T. Bretz, A. Bridgeman, F. L. Briechle, P. Buchholz, A. Bueno, S. Buitink, M. Buscemi, K. S. Caballero-Mora, L. Caccianiga, A. Cancio, F. Canfora, L. Caramete, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, L. Cazon, A. G. Chavez, J. A. Chinellato, J. Chudoba, R. W. Clay, A. Cobos, R. Colalillo, A. Coleman, L. Collica, M. R. Coluccia, R. Conceição, G. Consolati, F. Contreras, M. J. Cooper, S. Coutu, C. E. Covault, J. Cronin, S. D'Amico, B. Daniel, S. Dasso, K. Daumiller, B. R. Dawson, R. M. de Almeida, S. J. de Jong, G. De Mauro, J. R. T. de Mello Neto, I. De Mitri, J. de Oliveira, V. de Souza, J. Debatin, O. Deligny, M. L. Díaz Castro, F. Diogo, C. Dobrigkeit, J. C. D'Olivo, Q. Dorosti, R. C. dos Anjos, M. T. Dova, A. Dundovic, J. Ebr. 2017-10-19. Inferences on Mass Composition and Tests of Hadronic Interactions from 0.3 to 100 EeV using the water-Cherenkov Detectors of the Pierre Auger Observatory. https://arxiv.org/abs/1710.07249

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

GW231109_235456: A Sub-threshold Binary Neutron Star Merger in the LIGO-Virgo-KAGRA O4a Observing Run?

We present a sub-threshold search for gravitational-wave inspirals from binary neutron stars using data from the first part of the fourth LIGO--Virgo--KAGRA observing run. To enhance sensitivity to this targeted population, we adopt a population prior informed by the Galactic double neutron star population observed via radio pulsar surveys and by the confirmed GW170817 event. The search, with a sensitivity ~60% higher than standard GWTC-4.0 searches, recovers the previously sub-threshold candidate GW231109_235456 (reported in GWTC-4.0) with a network signal-to-noise ratio of 9.7 and an improved false-alarm rate of 1 per 60 years. Accounting for a trials factor of five, arising from the four previous searches and this new search, the false-alarm rate of the candidate is approximately 1 per 12 years. If the event is of astrophysical origin, the inferred source properties indicate component masses of 1.40 to 2.24 solar masses for the primary and 0.97 to 1.49 solar masses for the secondary, yielding a total mass of 2.95 solar masses with an uncertainty of plus 0.38 and minus 0.07 solar masses. The event is localized to a region of 430 square degrees (90% probability) at a luminosity distance of 165 megaparsecs with an uncertainty of plus 70 and minus 69 megaparsecs. Assuming the signal arises from a binary neutron star merger, this event would contribute a local merger rate of 53 to 342 per cubic gigaparsec per year (90% credible interval).

astro-ph.HE↗
arXiv2026

Gaussian-process evidence for a stochastic-variability transition in the recovering corona of 1ES 1927+654

We investigate the stochastic X-ray variability of the changing-look active galactic nucleus 1ES 1927+654 during its 2018--2024 evolution, focusing on the recovery of the X-ray corona after its 2018 collapse. Using XMM-Newton EPIC-pn light curves in the 0.3--2.0 keV and 2.0--10.0 keV bands, we model the variability with Gaussian process (GP) covariance components including Matérn-3/2, damped-random-walk (DRW), stochastically driven damped simple-harmonic-oscillator (SHO), and white-noise terms. Bayesian model comparison reveals an X-ray stochastic-variability transition during the changing-look recovery phase. In the 2019 May 5 observation, the preferred covariance changes from a Matérn-3/2-like state to a DRW-like state within a single continuous exposure. A phenomenological gated-kernel estimate localizes this transition sharply in the hard band at $t_c\simeq23.5~{\rm ks}$, while the soft band shows the same qualitative change over a broader interval. This transition occurs after the X-ray corona had reappeared but before the later pronounced hardening and brightening of the coronal emission, suggesting an early timing-domain signature of disk--corona reconfiguration. Phenomenologically, the dominant variability evolves from a smoother, finite-memory correlated process to a rougher, shorter-memory red-noise process. In the later 2022--2024 observations, SHO-like components associated with the known millihertz QPO show increasing characteristic frequency and quality factor, indicating a faster and more coherent oscillatory component during the QPO-plus-jet phase. GP-based time-domain inference therefore provides a sensitive probe of stochastic-variability changes in recovering AGN coronae.

astro-ph.HE↗
arXiv2026

Exploring the dynamics of the Coma galaxy cluster by mapping its X-ray emission line profiles with XRISM

The intracluster medium (ICM) in merging galaxy clusters exhibits turbulence and bulk flows. Unraveling these components is crucial not only for elucidating the geometry of the cluster mergers, but also for understanding the physics of magnetic field amplification and relativistic particle acceleration. XRISM/Resolve data for two $3'\times3'$ fields in the core of the Coma cluster reveales that the ICM in the central field moves with $Δcz = -430$~km~s$^{-1}$ relative to the cluster galaxy average, while that in the southern field moves with $Δcz = -730$~km~s$^{-1}$ (see \cite{2025ApJ...985L..20X}, hereinafter ``Paper I''). In this paper, we perform a more detailed analysis of these data sets to search for non-Gaussian features in the Fe-K line complex profiles. In the spectra from the northwest (NW) quadrant of the central field, in addition to the main and redshifted ICM components ($Δcz = -40$ km s$^{-1}$) reported in Paper I, we find evidence of another, blueshifted component, moving with $Δcz = -1250$ km s$^{-1}$. For a systematic search for other significant velocity components, we perform a bias-free 3 eV step multi-component fit to the Resolve full-array spectra from the central and southern fields. This search uncovers another redshifted component in the southern field, moving with $Δcz \sim +1230$ km s$^{-1}$. We estimate the energy densities of the ICM turbulence and bulk motion to be similar to each other and several times greater than the energy density of the cluster's $B\sim 5~μ$G magnetic field.

astro-ph.HE↗