Hunting for High-Mass X-ray Binaries in the Galactic Center with NuSTAR

Fuente: arXiv
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Autores principales: Mandel, Shifra, Gerber, Julian, Mori, Kaya, Stringfield, Ceaser, Peñaherrera, Mabel, Hailey, Charles J., Du, Alan, Grindlay, Jonathan, Hong, JaeSub, Ponti, Gabriele, Tomsick, John A., Berg, Maureen van den
Formato: Preprint
Publicado: 2025
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author Mandel, Shifra
Gerber, Julian
Mori, Kaya
Stringfield, Ceaser
Peñaherrera, Mabel
Hailey, Charles J.
Du, Alan
Grindlay, Jonathan
Hong, JaeSub
Ponti, Gabriele
Tomsick, John A.
Berg, Maureen van den
author_facet Mandel, Shifra
Gerber, Julian
Mori, Kaya
Stringfield, Ceaser
Peñaherrera, Mabel
Hailey, Charles J.
Du, Alan
Grindlay, Jonathan
Hong, JaeSub
Ponti, Gabriele
Tomsick, John A.
Berg, Maureen van den
contents The central $2\times0.8$ deg$^2$ region of our Galaxy contains $\sim10,000$ X-ray point sources that were detected by a series of Chandra observations over the last two decades. However, the limited bandpass of Chandra below 8 keV hampered their spectroscopic classification. In 2016, the initial NuSTAR Galactic center (GC) survey detected 77 X-ray sources above 10 keV (Hong et al. 2016). The hard X-ray detections indicate magnetic cataclysmic variables (CVs), low-mass X-ray binaries (LMXBs), high-mass X-ray binaries (HMXBs), or even pulsars. The possibility of HMXB detections is particularly interesting given the dearth of identified HMXBs in the GC. We conducted a search for bright ($K_s\lt16$ mag) near-infrared (NIR) counterparts to the hard X-ray sources $-$ utilizing their Chandra positions $-$ in order to identify HMXB candidates. We identified seven NuSTAR sources with NIR counterpart candidates whose magnitudes are consistent with HMXBs at the GC. We assessed the likelihood of random association for these seven sources and determined that two have a non-random association with a probability exceeding $99.98\%$, making them strong HMXB candidates. We analyzed broadband NuSTAR, Chandra and XMM-Newton spectral data for these two candidates, one of which was previously identified as a red supergiant. We find that the X-ray spectra are consistent with HMXBs. If confirmed through follow-up NIR spectroscopic studies, our findings will open a new window into our understanding of the intrinsic luminosity distribution of HMXBs in our Galaxy in general and the GC HMXB population in particular.
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id arxiv_https___arxiv_org_abs_2503_21139
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hunting for High-Mass X-ray Binaries in the Galactic Center with NuSTAR
Mandel, Shifra
Gerber, Julian
Mori, Kaya
Stringfield, Ceaser
Peñaherrera, Mabel
Hailey, Charles J.
Du, Alan
Grindlay, Jonathan
Hong, JaeSub
Ponti, Gabriele
Tomsick, John A.
Berg, Maureen van den
High Energy Astrophysical Phenomena
The central $2\times0.8$ deg$^2$ region of our Galaxy contains $\sim10,000$ X-ray point sources that were detected by a series of Chandra observations over the last two decades. However, the limited bandpass of Chandra below 8 keV hampered their spectroscopic classification. In 2016, the initial NuSTAR Galactic center (GC) survey detected 77 X-ray sources above 10 keV (Hong et al. 2016). The hard X-ray detections indicate magnetic cataclysmic variables (CVs), low-mass X-ray binaries (LMXBs), high-mass X-ray binaries (HMXBs), or even pulsars. The possibility of HMXB detections is particularly interesting given the dearth of identified HMXBs in the GC. We conducted a search for bright ($K_s\lt16$ mag) near-infrared (NIR) counterparts to the hard X-ray sources $-$ utilizing their Chandra positions $-$ in order to identify HMXB candidates. We identified seven NuSTAR sources with NIR counterpart candidates whose magnitudes are consistent with HMXBs at the GC. We assessed the likelihood of random association for these seven sources and determined that two have a non-random association with a probability exceeding $99.98\%$, making them strong HMXB candidates. We analyzed broadband NuSTAR, Chandra and XMM-Newton spectral data for these two candidates, one of which was previously identified as a red supergiant. We find that the X-ray spectra are consistent with HMXBs. If confirmed through follow-up NIR spectroscopic studies, our findings will open a new window into our understanding of the intrinsic luminosity distribution of HMXBs in our Galaxy in general and the GC HMXB population in particular.
title Hunting for High-Mass X-ray Binaries in the Galactic Center with NuSTAR
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2503.21139