Insight-HXMT Spectral and Timing Studies of a Giant Outburst in RX J0440.9+4431

Fuente: arXiv
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Main Authors: Epili, Prahlad R., Wang, Wei
Format: Preprint
Published: 2025
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author Epili, Prahlad R.
Wang, Wei
author_facet Epili, Prahlad R.
Wang, Wei
contents The Be/X-ray binary pulsar RX J0440.9+4431 underwent a giant outburst in late 2022 and lasted three months. The Insight-HXMT has observed this source at several instances of the entire outburst in 2022-2023. We used these bright outburst observations of the pulsar to study its X-ray spectral and timing variability. The pulse profiles obtained at similar luminosity during the progress and declining phases of the outburst show a similar shape behavior.With the increase in source luminosity, the complex pulse profile with multiple peaks at low luminosity becomes a single peaked pulse profile at the high luminosity at the outburst peak. The phase-averaged spectra of the pulsar in 1-120 keV are explained with an absorbed cutoff power-law continuum model. During the outburst phases, we have found the evidence of a cyclotron resonance scattering feature in the spectra varying in energies ($\sim$ 33.6- 41.6 keV) having broad linewidth > 5 keV . In declining phases of the outburst, we have also found the hints of first cyclotron harmonic varying in 65-75 keV . The application of thermal and bulk Comptonization model to the phase-averaged and phase-resolved spectra reveals a high surface magnetic field ($B \sim 10^{13}$ G) for the pulsar.
format Preprint
id arxiv_https___arxiv_org_abs_2507_18676
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Insight-HXMT Spectral and Timing Studies of a Giant Outburst in RX J0440.9+4431
Epili, Prahlad R.
Wang, Wei
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
High Energy Physics - Phenomenology
The Be/X-ray binary pulsar RX J0440.9+4431 underwent a giant outburst in late 2022 and lasted three months. The Insight-HXMT has observed this source at several instances of the entire outburst in 2022-2023. We used these bright outburst observations of the pulsar to study its X-ray spectral and timing variability. The pulse profiles obtained at similar luminosity during the progress and declining phases of the outburst show a similar shape behavior.With the increase in source luminosity, the complex pulse profile with multiple peaks at low luminosity becomes a single peaked pulse profile at the high luminosity at the outburst peak. The phase-averaged spectra of the pulsar in 1-120 keV are explained with an absorbed cutoff power-law continuum model. During the outburst phases, we have found the evidence of a cyclotron resonance scattering feature in the spectra varying in energies ($\sim$ 33.6- 41.6 keV) having broad linewidth > 5 keV . In declining phases of the outburst, we have also found the hints of first cyclotron harmonic varying in 65-75 keV . The application of thermal and bulk Comptonization model to the phase-averaged and phase-resolved spectra reveals a high surface magnetic field ($B \sim 10^{13}$ G) for the pulsar.
title Insight-HXMT Spectral and Timing Studies of a Giant Outburst in RX J0440.9+4431
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2507.18676