Cloud-cloud collisions in the Antennae galaxies: Does high-speed collision suppress star formation?
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| Format: | Preprint |
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2025
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| _version_ | 1866915213607960576 |
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| author | Inoue, Shin Ohta, Kouji Maeda, Fumiya |
| author_facet | Inoue, Shin Ohta, Kouji Maeda, Fumiya |
| contents | Cloud-cloud collision (CCC) has been proposed as a mechanism for triggering massive star formation. Observations in the Milky Way and nearby galaxies have revealed the presence of CCCs with collision velocity ($v_{\rm col}$) of 1-40 km/s, and the connection between star formation activity and the properties of colliding clouds has been investigated. In this study, we expand the study to much faster (~100 km/s) CCCs in a nearby colliding galaxies system, the Antennae galaxies. We examine how star formation rate (SFR) on a sub-kpc scale depends on the $v_{\rm col}$ and mass ($M_{\rm mol}$) of giant molecular clouds (GMCs) across the Antennae galaxies, which show diverse star formation activity. Furthermore, to examine the star formation process at a more fundamental level, we also investigate how the star formation efficiency (SFE) of a colliding GMC depends on its $v_{\rm col}$ and $M_{\rm mol}$. SFR is calculated using H$α$ and mid-infrared data. From $\sim2000$ GMCs identified in the CO(1-0) data cube using the ALMA archival data, collision velocities are estimated based on the velocity dispersion among GMCs in a sub-kpc scale region, assuming random motion in three-dimensional space. GMCs are considered to be colliding at a velocity of ~10-150 km/s. We find that regions where high-speed collisions ($v_{\rm col}$~100 km/s) of massive ($M_{\rm mol}$~$10^{7-8}$ $M_\odot$) GMCs are seen show the highest surface density of SFR. Particularly, in the region with $v_{\rm col}$~100 km/s, we find that SFR on a sub-kpc scale increases with increasing $M_{\rm mol}$ in the range of ~$10^{6}$-$10^{8}$ $M_\odot$. The SFE of a colliding cloud is estimated to be 0.1%-3.0% without clear $M_{\rm mol}$ dependence, and the SFE is the lowest at the $v_{\rm col}$~100-150 km/s. These results suggest that the most active star formation in the Antennae galaxies seems to occur due to large GMC mass. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_17951 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Cloud-cloud collisions in the Antennae galaxies: Does high-speed collision suppress star formation? Inoue, Shin Ohta, Kouji Maeda, Fumiya Astrophysics of Galaxies Cloud-cloud collision (CCC) has been proposed as a mechanism for triggering massive star formation. Observations in the Milky Way and nearby galaxies have revealed the presence of CCCs with collision velocity ($v_{\rm col}$) of 1-40 km/s, and the connection between star formation activity and the properties of colliding clouds has been investigated. In this study, we expand the study to much faster (~100 km/s) CCCs in a nearby colliding galaxies system, the Antennae galaxies. We examine how star formation rate (SFR) on a sub-kpc scale depends on the $v_{\rm col}$ and mass ($M_{\rm mol}$) of giant molecular clouds (GMCs) across the Antennae galaxies, which show diverse star formation activity. Furthermore, to examine the star formation process at a more fundamental level, we also investigate how the star formation efficiency (SFE) of a colliding GMC depends on its $v_{\rm col}$ and $M_{\rm mol}$. SFR is calculated using H$α$ and mid-infrared data. From $\sim2000$ GMCs identified in the CO(1-0) data cube using the ALMA archival data, collision velocities are estimated based on the velocity dispersion among GMCs in a sub-kpc scale region, assuming random motion in three-dimensional space. GMCs are considered to be colliding at a velocity of ~10-150 km/s. We find that regions where high-speed collisions ($v_{\rm col}$~100 km/s) of massive ($M_{\rm mol}$~$10^{7-8}$ $M_\odot$) GMCs are seen show the highest surface density of SFR. Particularly, in the region with $v_{\rm col}$~100 km/s, we find that SFR on a sub-kpc scale increases with increasing $M_{\rm mol}$ in the range of ~$10^{6}$-$10^{8}$ $M_\odot$. The SFE of a colliding cloud is estimated to be 0.1%-3.0% without clear $M_{\rm mol}$ dependence, and the SFE is the lowest at the $v_{\rm col}$~100-150 km/s. These results suggest that the most active star formation in the Antennae galaxies seems to occur due to large GMC mass. |
| title | Cloud-cloud collisions in the Antennae galaxies: Does high-speed collision suppress star formation? |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2503.17951 |