X-ray observations of Blueberry galaxies
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866913566808866816 |
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| author | Adamcová, B. Svoboda, J. Kyritsis, E. Kouroumpatzakis, K. Zezas, A. Boorman, P. G. Borkar, A. Bílek, M. Clavel, M. Petrucci, P. -O. |
| author_facet | Adamcová, B. Svoboda, J. Kyritsis, E. Kouroumpatzakis, K. Zezas, A. Boorman, P. G. Borkar, A. Bílek, M. Clavel, M. Petrucci, P. -O. |
| contents | Compact star-forming galaxies were dominant galaxy types in the early Universe. Blueberry galaxies (BBs) represent their local analogues being very compact and having intensive star formation. Motivated by high X-ray emission recently found in other analogical dwarf galaxies, called Green Peas, we probe into the X-ray properties of BBs to determine if their X-ray emission is consistent with the empirical laws for star-forming galaxies. We performed the first X-ray observations of a small sample of BBs with the XMM-Newton satellite. Spectral analysis for detected sources and upper limits measured via Bayesian-based analysis for very low-count measurements were used to determine the X-ray properties of our galaxy sample. Clear detection was obtained only for 2 sources, with one source exhibiting an enhanced X-ray luminosity to the scaling relations. For the remaining 5 sources, only an upper limit was constrained, suggesting BBs to be rather underluminous as a whole. Our analysis shows that the large scatter cannot be easily explained by the stochasticity effects. While the bright source is above and inconsistent at almost the 99% confidence level, the upper limits of the two sources are below the expected distribution. These results indicate that the empirical relations between the star formation rate, metallicity, and X-ray luminosity might not hold for BBs with uniquely high specific star formation rates. One possible explanation could be that the BBs may not be old enough to have a significant X-ray binary population. The high luminosity of the only bright source can be then caused by an additional X-ray source, such as a hidden active galactic nucleus or more extreme ultraluminous X-ray sources. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2408_13572 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | X-ray observations of Blueberry galaxies Adamcová, B. Svoboda, J. Kyritsis, E. Kouroumpatzakis, K. Zezas, A. Boorman, P. G. Borkar, A. Bílek, M. Clavel, M. Petrucci, P. -O. Astrophysics of Galaxies Compact star-forming galaxies were dominant galaxy types in the early Universe. Blueberry galaxies (BBs) represent their local analogues being very compact and having intensive star formation. Motivated by high X-ray emission recently found in other analogical dwarf galaxies, called Green Peas, we probe into the X-ray properties of BBs to determine if their X-ray emission is consistent with the empirical laws for star-forming galaxies. We performed the first X-ray observations of a small sample of BBs with the XMM-Newton satellite. Spectral analysis for detected sources and upper limits measured via Bayesian-based analysis for very low-count measurements were used to determine the X-ray properties of our galaxy sample. Clear detection was obtained only for 2 sources, with one source exhibiting an enhanced X-ray luminosity to the scaling relations. For the remaining 5 sources, only an upper limit was constrained, suggesting BBs to be rather underluminous as a whole. Our analysis shows that the large scatter cannot be easily explained by the stochasticity effects. While the bright source is above and inconsistent at almost the 99% confidence level, the upper limits of the two sources are below the expected distribution. These results indicate that the empirical relations between the star formation rate, metallicity, and X-ray luminosity might not hold for BBs with uniquely high specific star formation rates. One possible explanation could be that the BBs may not be old enough to have a significant X-ray binary population. The high luminosity of the only bright source can be then caused by an additional X-ray source, such as a hidden active galactic nucleus or more extreme ultraluminous X-ray sources. |
| title | X-ray observations of Blueberry galaxies |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2408.13572 |