The hard ultraluminous state of NGC 5055 ULX X-1
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| author | Cruz-Sanchez, N. Saavedra, E. A. Fogantini, F. A. García, F. Combi, J. A. |
| author_facet | Cruz-Sanchez, N. Saavedra, E. A. Fogantini, F. A. García, F. Combi, J. A. |
| contents | We present the results of the first broadband X-ray analysis of the ultraluminous X-ray source NGC 5055 ULX X-1, combining simultaneous data from XMM$-$Newton and NuSTAR missions, with a combined exposure time of $\sim$100 ks across the $0.3-20$ keV energy range. The source exhibits a stable flux across the entire exposure with no detectable pulsations by any instrument on their X-ray light curves, placing pulsed-fraction upper limits of 10% and 32% for XMM$-$Newton and NuSTAR, respectively. The X-ray spectrum is dominated by two thermal components consistent with the emission from an accretion disk, and shows a weak high-energy tail above 10 keV, with no statistical requirement for an additional nonthermal component. The unabsorbed $0.3-20$ keV luminosity is ${\sim}2\times10^{40}$ erg s$^{-1}$, evidencing the ULX nature of the source. The parameters obtained from spectral modeling are consistent with the hard ultraluminous state. Despite the fact that a neutron-star accretor cannot be ruled out by the available data, under the assumption that the compact object in NGC 5055 ULX X-1 is a black hole accreting through a geometrically thick, radiation-pressure-supported disk that drives an optically thick wind, we constrained its putative mass to $11-26$ M$_{\odot}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_13686 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The hard ultraluminous state of NGC 5055 ULX X-1 Cruz-Sanchez, N. Saavedra, E. A. Fogantini, F. A. García, F. Combi, J. A. High Energy Astrophysical Phenomena We present the results of the first broadband X-ray analysis of the ultraluminous X-ray source NGC 5055 ULX X-1, combining simultaneous data from XMM$-$Newton and NuSTAR missions, with a combined exposure time of $\sim$100 ks across the $0.3-20$ keV energy range. The source exhibits a stable flux across the entire exposure with no detectable pulsations by any instrument on their X-ray light curves, placing pulsed-fraction upper limits of 10% and 32% for XMM$-$Newton and NuSTAR, respectively. The X-ray spectrum is dominated by two thermal components consistent with the emission from an accretion disk, and shows a weak high-energy tail above 10 keV, with no statistical requirement for an additional nonthermal component. The unabsorbed $0.3-20$ keV luminosity is ${\sim}2\times10^{40}$ erg s$^{-1}$, evidencing the ULX nature of the source. The parameters obtained from spectral modeling are consistent with the hard ultraluminous state. Despite the fact that a neutron-star accretor cannot be ruled out by the available data, under the assumption that the compact object in NGC 5055 ULX X-1 is a black hole accreting through a geometrically thick, radiation-pressure-supported disk that drives an optically thick wind, we constrained its putative mass to $11-26$ M$_{\odot}$. |
| title | The hard ultraluminous state of NGC 5055 ULX X-1 |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2511.13686 |