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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2505.20019 |
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| _version_ | 1866916759790944256 |
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| author | Manca, A. Marino, A. Borghese, A. Zelati, F. Coti Mastroserio, G. Sanna, A. Homan, J. Connors, R. Del Santo, M. Padilla, M. Armas Muñoz-Darias, T. Di Salvo, T. Rea, N. García, J. A. Riggio, A. Baglio, M. C. Burderi, L. |
| author_facet | Manca, A. Marino, A. Borghese, A. Zelati, F. Coti Mastroserio, G. Sanna, A. Homan, J. Connors, R. Del Santo, M. Padilla, M. Armas Muñoz-Darias, T. Di Salvo, T. Rea, N. García, J. A. Riggio, A. Baglio, M. C. Burderi, L. |
| contents | 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 showed a main peak followed by a second activity phase. The majority of the spectra extracted from the individual NICER observations could be adequately fitted with a Comptonisation component alone, while a few of them required an additional thermal component. The spectral evolution is consistent with a softening trend as the source gets brighter in X-rays. We also analysed the broadband spectrum combining data from simultaneous NICER and NuStar observations on 2023 March 10. This spectrum can be fitted with a disc component with a temperature at the inner radius of $kT_{\rm in} \sim 0.4$ keV and a Comptonisation component with a power-law photon index of $Γ\sim 1.8$. By including a reflection component in the modelling, we obtained a 3$σ$ upper limit for the inner disc radius of 11.4 gravitational radii. We also detected a quasi-periodic oscillation (QPO), whose central frequency varies with time (from 2 Hz to $\sim$0.9 Hz) and anti-correlates with the hardness ratio. Based on the observed spectral-timing properties, MAXI J1834-021, can be classified as a low-mass X-ray binary in outburst. However, we are not able to draw a definitive conclusion on the nature of the accreting compact object, which at the moment could as well be a black hole or a neutron star. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_20019 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On the nature of the X-ray binary transient MAXI J1834-021: clues from its first observed outburst Manca, A. Marino, A. Borghese, A. Zelati, F. Coti Mastroserio, G. Sanna, A. Homan, J. Connors, R. Del Santo, M. Padilla, M. Armas Muñoz-Darias, T. Di Salvo, T. Rea, N. García, J. A. Riggio, A. Baglio, M. C. Burderi, L. High Energy Astrophysical Phenomena 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 showed a main peak followed by a second activity phase. The majority of the spectra extracted from the individual NICER observations could be adequately fitted with a Comptonisation component alone, while a few of them required an additional thermal component. The spectral evolution is consistent with a softening trend as the source gets brighter in X-rays. We also analysed the broadband spectrum combining data from simultaneous NICER and NuStar observations on 2023 March 10. This spectrum can be fitted with a disc component with a temperature at the inner radius of $kT_{\rm in} \sim 0.4$ keV and a Comptonisation component with a power-law photon index of $Γ\sim 1.8$. By including a reflection component in the modelling, we obtained a 3$σ$ upper limit for the inner disc radius of 11.4 gravitational radii. We also detected a quasi-periodic oscillation (QPO), whose central frequency varies with time (from 2 Hz to $\sim$0.9 Hz) and anti-correlates with the hardness ratio. Based on the observed spectral-timing properties, MAXI J1834-021, can be classified as a low-mass X-ray binary in outburst. However, we are not able to draw a definitive conclusion on the nature of the accreting compact object, which at the moment could as well be a black hole or a neutron star. |
| title | On the nature of the X-ray binary transient MAXI J1834-021: clues from its first observed outburst |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2505.20019 |