The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies
We present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7−7 pc) radio sources in the central ∼250 pc region of NGC 3628. Based on their morphology, high radio-brightness temperatures (10 ^5...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acd765 |
| _version_ | 1797698976484425728 |
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| author | Xiaolong Yang Ziwei Ou |
| author_facet | Xiaolong Yang Ziwei Ou |
| author_sort | Xiaolong Yang |
| collection | DOAJ |
| description | We present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7−7 pc) radio sources in the central ∼250 pc region of NGC 3628. Based on their morphology, high radio-brightness temperatures (10 ^5 –10 ^7 K), and steep radio spectra, none of these seven sources can be associated with active galactic nuclei (AGNs); instead, they can be identified as supernova remnants (SNRs), with three of them appearing consistent with partial shells. Notably, one of them (W2) is likely a nascent radio supernova (SN) and appears to be consistent with the star formation rate of NGC 3628 when assuming a canonical initial mass function. The VLBI observation provides the first precise measurement of the diameter of the radio sources in NGC 3628, which allow us to fit a well-constrained radio surface brightness—diameter (Σ– D ) correlation by including the detected SNRs. Furthermore, future VLBI observations can be conducted to measure the expansion velocity of the detected SNRs. In addition to our radio VLBI study, we analyze Chandra and XMM-Newton spectra of NGC 3628. The spectral fitting indicates that the SNR activities could well account for the observed X-ray emissions. Along with the Chandra X-ray image, it further reveals that the X-ray emission is likely maintained by the galactic-scale outflow triggered by SN activities. These results provide strong evidence that SN-triggered activities play a critical role in generating both radio and X-ray emissions in NGC 3628. |
| first_indexed | 2024-03-12T04:01:52Z |
| format | Article |
| id | doaj.art-98cc6035952a449a8eda9a1cb5f09288 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:01:52Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-98cc6035952a449a8eda9a1cb5f092882023-09-03T11:34:11ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195212710.3847/1538-4357/acd765The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray StudiesXiaolong Yang0https://orcid.org/0000-0002-4439-5580Ziwei Ou1https://orcid.org/0000-0002-3632-474XShanghai Astronomical Observatory, Chinese Academy of Sciences , Shanghai 200030, People's Republic of China ; yangxl@shao.ac.cn; Shanghai Key Laboratory of Space Navigation and Positioning Techniques , Shanghai 200030, People's Republic of ChinaSchool of Physics and Astronomy, Sun Yat-sen University , Zhuhai 519082, People's Republic of China ; ouzw3@mail.sysu.edu.cnWe present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7−7 pc) radio sources in the central ∼250 pc region of NGC 3628. Based on their morphology, high radio-brightness temperatures (10 ^5 –10 ^7 K), and steep radio spectra, none of these seven sources can be associated with active galactic nuclei (AGNs); instead, they can be identified as supernova remnants (SNRs), with three of them appearing consistent with partial shells. Notably, one of them (W2) is likely a nascent radio supernova (SN) and appears to be consistent with the star formation rate of NGC 3628 when assuming a canonical initial mass function. The VLBI observation provides the first precise measurement of the diameter of the radio sources in NGC 3628, which allow us to fit a well-constrained radio surface brightness—diameter (Σ– D ) correlation by including the detected SNRs. Furthermore, future VLBI observations can be conducted to measure the expansion velocity of the detected SNRs. In addition to our radio VLBI study, we analyze Chandra and XMM-Newton spectra of NGC 3628. The spectral fitting indicates that the SNR activities could well account for the observed X-ray emissions. Along with the Chandra X-ray image, it further reveals that the X-ray emission is likely maintained by the galactic-scale outflow triggered by SN activities. These results provide strong evidence that SN-triggered activities play a critical role in generating both radio and X-ray emissions in NGC 3628.https://doi.org/10.3847/1538-4357/acd765Supernova remnantsRadio sourcesVery long baseline interferometryStarburst galaxiesX-ray sources |
| spellingShingle | Xiaolong Yang Ziwei Ou The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies The Astrophysical Journal Supernova remnants Radio sources Very long baseline interferometry Starburst galaxies X-ray sources |
| title | The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies |
| title_full | The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies |
| title_fullStr | The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies |
| title_full_unstemmed | The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies |
| title_short | The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies |
| title_sort | core starbursts of the galaxy ngc 3628 radio very long baseline interferometry and x ray studies |
| topic | Supernova remnants Radio sources Very long baseline interferometry Starburst galaxies X-ray sources |
| url | https://doi.org/10.3847/1538-4357/acd765 |
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