Disclosing Submillimeter Galaxy Formation: Mergers or Secular Evolution?
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2025
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| _version_ | 1866912752897884160 |
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| author | Chan, Siu-Wang Ao, Yiping Tan, Qinghua |
| author_facet | Chan, Siu-Wang Ao, Yiping Tan, Qinghua |
| contents | We analyze the morphology of 125 submillimeter galaxies (SMGs) in the PRIMER-COSMOS field using double Sersic modeling on JWST NIRCam images across six bands (F150W, F200W, F277W, F356W, F410M and F444W), with SMGs being classified by bulge Sersic index (n_bulge) and bulge-to-total luminosity ratio (B/T). The Kolmogorov-Smirnov test between the bright (SFR > 175 M_sun yr^{-1}) and the faint group (SFR < 175 M_sun yr^{-1}) reveals no significant statistical differences in morphology across bands. However, we notice that SMGs skew towards higher B/T ratios and lower n_bulge from shorter to longer wavelengths. In F444W, bright SMGs exhibit higher B/T and lower n_bulge, indicating flatter, disturbed bulges, while faint SMGs show lower B/T and higher n_bulge. Notably, SMGs with higher B/T tend to have low Sersic index, challenging the local universe dichotomy of classical bulges (B/T > 0.5, n > 4) versus pseudo-bulges (B/T < 0.35, n < 2). In the F277W band, non-parametric measurements indicate predominantly disk-dominated patterns, with only 24 percent of SMGs demonstrating merger signatures. After the removal of SMGs with disturbed morphology, the bulge classification scheme in F277W shows pseudo-bulges (21 percent) and clump migration bulges (16 percent) from secular evolution, compared to 4 percent merger-built bulges. Surprisingly, 48 percent of SMGs defy the classification scheme, showing high B/T (approximately 0.7) but low Sersic index (n_bulge <= 1). Bars are confirmed in 7 percent of SMGs. This work suggests that secular evolution takes precedence over major mergers, supporting the idea that isolated evolution fueled by filamentary gas inflow plays a non-negligible role in the SMG bulge formation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_07913 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Disclosing Submillimeter Galaxy Formation: Mergers or Secular Evolution? Chan, Siu-Wang Ao, Yiping Tan, Qinghua Astrophysics of Galaxies We analyze the morphology of 125 submillimeter galaxies (SMGs) in the PRIMER-COSMOS field using double Sersic modeling on JWST NIRCam images across six bands (F150W, F200W, F277W, F356W, F410M and F444W), with SMGs being classified by bulge Sersic index (n_bulge) and bulge-to-total luminosity ratio (B/T). The Kolmogorov-Smirnov test between the bright (SFR > 175 M_sun yr^{-1}) and the faint group (SFR < 175 M_sun yr^{-1}) reveals no significant statistical differences in morphology across bands. However, we notice that SMGs skew towards higher B/T ratios and lower n_bulge from shorter to longer wavelengths. In F444W, bright SMGs exhibit higher B/T and lower n_bulge, indicating flatter, disturbed bulges, while faint SMGs show lower B/T and higher n_bulge. Notably, SMGs with higher B/T tend to have low Sersic index, challenging the local universe dichotomy of classical bulges (B/T > 0.5, n > 4) versus pseudo-bulges (B/T < 0.35, n < 2). In the F277W band, non-parametric measurements indicate predominantly disk-dominated patterns, with only 24 percent of SMGs demonstrating merger signatures. After the removal of SMGs with disturbed morphology, the bulge classification scheme in F277W shows pseudo-bulges (21 percent) and clump migration bulges (16 percent) from secular evolution, compared to 4 percent merger-built bulges. Surprisingly, 48 percent of SMGs defy the classification scheme, showing high B/T (approximately 0.7) but low Sersic index (n_bulge <= 1). Bars are confirmed in 7 percent of SMGs. This work suggests that secular evolution takes precedence over major mergers, supporting the idea that isolated evolution fueled by filamentary gas inflow plays a non-negligible role in the SMG bulge formation. |
| title | Disclosing Submillimeter Galaxy Formation: Mergers or Secular Evolution? |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.07913 |