Explanipedia

The 2025 outburst of IGR J17511−3057: Timing and spectral insights from NICER and NuSTAR Open

A. Sanna, G. K. Jaisawal, T. E. Strohmayer, Giulia Illiano, A. Riggio , et al. · 2025

Context. IGR J17511−3057 is an accreting millisecond X-ray pulsar and a known type-I burster. The source was observed in outburst for the first time in 2009 and again in 2015, followed by a decade-long quiescence phase. Aims. The source wa…

Time domain astrophysics with transient sources Open

W. Leone, L. Burderi, T. di Salvo, A. Anitra, A. Sanna , et al. · 2025

The timing analysis of transient events allows for investigating numerous still open areas of modern astrophysics. The article explores all the mathematical and physical tools required to estimate delays and associated errors between two T…

The nature of the X-ray binary transient MAXI J1834–021: Clues from its first observed outburst Open

A. Manca, A. Marino, A. Borghese, F. Coti Zelati, Guglielmo Mastroserio , et al. · 2025

MAXI J1834–021 is a new X-ray transient discovered in February 2023. We analysed the spectral and timing properties of MAXI J1834–021 using NICER , NuSTAR and Swift data collected between March and October 2023. The light curve showed a ma…

On the nature of the X-ray binary transient MAXI J1834-021: clues from its first observed outburst Open

A. Manca, A. Marino, A. Borghese, F. Coti Zelati, Guglielmo Mastroserio , et al. · 2025

MAXI J1834-021 is a new X-ray transient that was discovered in February 2023. We analysed the spectral and timing properties of MAXI J1834-021 using NICER, NuStar and Swift data collected between March and October 2023. The light curve sho…

Gamma-ray burst taxonomy: Looking for the third class on the spectral peak energy-duration plane in the rest frame Open

A. Tsvetkova, L. Amati, Mattia Bulla, L. Burderi, D. Frederiks , et al. · 2025

Context. Two classes of gamma-ray bursts (GRBs) corresponding to the short-hard and the long-soft events, with a putative intermediate class, are typically considered in the observer frame. However, when considering GRB characteristics in …

Identification and characterisation of the gamma-ray counterpart of the transitional pulsar candidate CXOU J110926.4–650224 Open

Antonella Manca, F. Coti Zelati, Junru Li, D. F. Torres, J. Ballet , et al. · 2025

Transitional millisecond pulsars (tMSPs) represent a crucial link between the rotation-powered and accretion-powered states of binary pulsars. During their active X-ray state, tMSPs are the only low-mass X-ray binary systems detected up to…

HERMES Pathfinder & SpIRIT: a progress report Open

F. Fiore, Michele Trenti, Y. Evangelista, R. Campana, G. Baroni , et al. · 2025

HERMES Pathfinder is an in-orbit demonstration consisting of a constellation of six 3U cubesats hosting simple but innovative X-ray/gamma-ray detectors for the monitoring of cosmic high-energy transients. HERMES-PF, funded by ASI and by th…

New semicoherent targeted search for continuous gravitational waves from pulsars in binary systems Open

L. Mirasola, P. Leaci, P. Astone, L. D’Onofrio, S. Dall’Osso , et al. · 2024

We present a novel semicoherent targeted search method for continuous gravitational waves (CWs) emitted by pulsars in binary systems. The method is based on a custom optimization of the coherence time, which is tailored according to the or…

Investigations on η’ photoproduction off quasi-free neutron Open

A. Riggio · 2024

The HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder mission Open

Y. Evangelista, F. Fiore, R. Campana, Giulia Baroni, Francesco Ceraudo , et al. · 2024

HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder is a\nspace-borne mission based on a constellation of six nano-satellites flying in a\nlow-Earth orbit (LEO). The 3U CubeSats, to be launched in early 2025, host\nminiatu…

HERMES: Gamma-ray burst and gravitational wave counterpart hunter Open

G. Ghirlanda, Lara Nava, O. S. Salafia, F. Fiore, R. Campana , et al. · 2024

Gamma-ray bursts (GRBs) bridge relativistic astrophysics and multimessenger astronomy. Space–based γ - and X-ray wide-field detectors have proven essential for detecting and localizing the highly variable GRB prompt emission, which is also…

HERMES: Gamma Ray Burst and Gravitational Wave counterpart hunter Open

G. Ghirlanda, Lara Nava, O. S. Salafia, F. Fiore, R. Campana , et al. · 2024

Gamma Ray Bursts (GRBs) bridge relativistic astrophysics and multi-messenger astronomy. Space-based gamma/X-ray wide field detectors have proven essential to detect and localize the highly variable GRB prompt emission, which is also a coun…

The puzzling orbital residuals of XTE J1710–281: Is a Jovian planet orbiting the binary system? Open

R. Iaria, T. Di Salvo, A. Anitra, C. Miceli, W. Leone , et al. · 2024

Aims. XTE J1710−281 is a transient eclipsing binary system with a period close to 3.28 h that hosts a neutron star. The average eclipse duration is 420 s, and eclipse arrival times reported in the literature span from 1999 to 2017. A previ…

New semicoherent targeted search for continuous gravitational waves from pulsars in binary systems Open

L. Mirasola, P. Leaci, P. Astone, L. D’Onofrio, S. Dall’Osso , et al. · 2024

We present a novel semicoherent targeted search method for continuous gravitational waves (CWs) emitted by pulsars in binary systems. The method is based on a custom optimization of the coherence time, which is tailored according to the or…

Confirmation of the presence of a CRSF in the NICER spectrum of X 1822-371 Open

R. Iaria, T. Di Salvo, A. Anitra, C. Miceli, F. Barra , et al. · 2024

X 1822-371 is an eclipsing binary system with a period close to 5.57 hr and an orbital period derivative $\dot{P}_{\rm orb}$ of 1.42(3)$\times 10^{-10}$ s s$^{-1}$. The extremely high value of its $\dot{P}_{\rm orb}$ is compatible with a s…

Confirmation of the presence of a CRSF in the NICER spectrum of X 1822-371 Open

R. Iaria, T. Di Salvo, A. Anitra, C. Miceli, F. Barra , et al. · 2024

Aims. X 1822-371 is an eclipsing binary system with a period close to 5.57 h and an orbital period derivative Ṗ orb of 1.42(3) × 10 −10 s s −1 . The extremely high value of its Ṗ orb is compatible with a super-Eddington mass transfer rate …

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation – CORRIGENDUM Open

M. Thomas, Michele Trenti, A. Sanna, R. Campana, G. Ghirlanda , et al. · 2024

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Spectral analysis of the LMXB XTE J1810−189 with NICER data Open

Antonella Manca, A. Sanna, A. Marino, T. Di Salvo, S. M. Mazzola , et al. · 2023

X-ray Timing Explorer J1810−189 is a low-mass X-ray binary transient system hosting a neutron star, which underwent a three-month-long outburst in 2020. In order to study its spectral evolution during this outburst, we analysed all the ava…

Spectral Analysis of the LMXB XTE J1810-189 with NICER Data Open

A. Manca, A. Sanna, A. Marino, T. Di Salvo, S. M. Mazzola , et al. · 2023

XTE J1810-189 is a Low-Mass X-ray Binary transient system hosting a neutron star, which underwent a three-month-long outburst in 2020. In order to study its spectral evolution during this outburst, we analysed all the available observation…

A Concept of Assessment of LIV Tests with THESEUS Using the Gamma-Ray Bursts Detected by Fermi/GBM Open

A. Tsvetkova, L. Burderi, A. Riggio, A. Sanna, T. Di Salvo · 2023

According to Einstein’s special relativity theory, the speed of light in a vacuum is constant for all observers. However, quantum gravity effects could introduce its dispersion depending on the energy of photons. The investigation of the s…

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation Open

Matt Thomas, Michele Trenti, R. Campana, G. Ghirlanda, J. Řípa , et al. · 2023

Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorptio…

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation Open

M. Thomas, Michele Trenti, A. Sanna, R. Campana, G. Ghirlanda , et al. · 2023

Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorptio…

Spectral analysis of the AMXP IGR J17591–2342 during its 2018 outburst Open

Antonella Manca, A. F. Gambino, A. Sanna, Gaurava K. Jaisawal, T. Di Salvo , et al. · 2022

The Accreting Millisecond X-ray Pulsar IGR J17591–2342 is a Low Mass X-ray Binary (LMXB) system that went in outburst on 2018 August and it was monitored by the NICER observatory and partially by other facilities. We aim to study how the s…

MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary Open

A. Sanna, Peter Bult, Mason Ng, Paul S. Ray, Gaurava K. Jaisawal , et al. · 2022

The detection of coherent X-ray pulsations at ∼314 Hz (3.2 ms) classifies MAXI J1957+032 as a fast-rotating, accreting neutron star. We present the temporal and spectral analysis performed using NICER observations collected during the late…

MAXI J1957+032: a new accreting millisecond X-ray pulsar in an ultra-compact binary Open

A. Sanna, P. Bult, Mason Ng, Paul S. Ray, G. K. Jaisawal , et al. · 2022

The detection of coherent X-ray pulsations at ~314 Hz (3.2 ms) classifies MAXI J1957+032 as a fast-rotating, accreting neutron star. We present the temporal and spectral analysis performed using NICER observations collected during the late…

Outflows and spectral evolution in the eclipsing AMXP SWIFT J1749.4–2807 with NICER, XMM-Newton, and NuSTAR Open

A. Marino, A. Anitra, S. M. Mazzola, T. Di Salvo, A. Sanna , et al. · 2022

The neutron star low-mass X-ray binary SWIFT J1749.4–2807 is the only known eclipsing accreting millisecond X-ray pulsar. In this manuscript, we perform a spectral characterization of the system throughout its 2021, 2-week-long outburst, a…

On the peculiar long-term orbital evolution of the eclipsing accreting millisecond X-ray pulsar SWIFT J1749.4 − 2807 Open

A. Sanna, L. Burderi, T. Di Salvo, A. Riggio, D. Altamirano , et al. · 2022

We present the pulsar timing analysis of the accreting millisecond X-ray pulsar SWIFT J1749.4 − 2807 monitored by NICER and XMM–Newton during its latest outburst after almost 11 yr of quiescence. From the coherent timing analysis of the pu…

Quantum gravity with THESEUS Open

L. Burderi, A. Sanna, T. Di Salvo, A. Riggio, R. Iaria , et al. · 2021

In this paper we explore the possibility to search for a dispersion law for light propagation in vacuo with a sample of Gamma-Ray Bursts detected by the THESEUS satellite. Within Quantum Gravity theories, different models for space-time qu…

Time domain astronomy with the THESEUS satellite Open

S. Mereghetti, Ş. Balman, M. D. Caballero‐García, M. Del Santo, Victor Doroshenko , et al. · 2021

Fe Kαand Fe Kβline detection in theNuSTARspectrum of the ultra-bright Z source Scorpius X–1 Open

S. M. Mazzola, R. Iaria, T. Di Salvo, A. Sanna, A. F. Gambino , et al. · 2021

Context. Low-mass X-ray binaries hosting a low-magnetised neutron star, which accretes matter via Roche-lobe overflow, are generally grouped into two classes called Atoll and Z sources after the path described in their X-ray colour-colour …

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