Radio continuum size evolution of star-forming galaxies over 0.35 < z < 2.25
Radio continuum size evolution of star-forming galaxies over 0.35 < z < 2.25
复制标题
DOI：
10.1051/0004-6361/201935178
复制
发表时间：
2019-03
影响因子：
6.5
通讯作者：
E. F. Jim'enez-Andrade;B. Magnelli;A. Karim;G. Zamorani;M. Bondi;E. Schinnerer;M. Sargent;E. Romano-D'iaz;M. Novak;P. Lang;F. Bertoldi;E. Vardoulaki;S. Toft;V. Smolčić;K. Harrington;S. Leslie;J. Delhaize;Daizhong Liu;C. Karoumpis;J. Kartaltepe;A. Koekemoer
中科院分区：
文献类型：
--
作者：
E. F. Jim'enez-Andrade;B. Magnelli;A. Karim;G. Zamorani;M. Bondi;E. Schinnerer;M. Sargent;E. Romano-D'iaz;M. Novak;P. Lang;F. Bertoldi;E. Vardoulaki;S. Toft;V. Smolčić;K. Harrington;S. Leslie;J. Delhaize;Daizhong Liu;C. Karoumpis;J. Kartaltepe;A. Koekemoer
为了更好地解释星星形成的物理机制，我们首次系统地研究了红移0.35 < z < 2.25范围内恒星形成星系（SFG）的射电连续谱尺度演化.我们使用VLA COSMOS 3 GHz地图（噪声rms = 2.3 μJy beam-1，θbeam = 0.75 arcsec）来构建3184个无线电选择的SFG的质量完整样本，这些SFG位于SFG的主序列（MS）之上。我们通过应用二维高斯模型来限制星系中星星形成活动的总体范围。广泛的Monte Carlo模拟被用来验证我们的测量的鲁棒性和特征的选择函数。我们发现射电大小和恒星质量M_∞之间没有明显的依赖关系，SFG的10.5 μ log（M_∞/M_∞）<$11.5。我们的分析表明，MS星系优先扩展，而SFG以上的MS总是紧凑的。参考MS上（上方）SFG的中值有效半径= 1.5 ± 0.2（1.0 ± 0.2）kpc随宇宙时间几乎保持恒定;参数化的形式为Reff（1 + z）α，得到的斜率很小，仅为α = −0.26 ± 0.08（0.12 ± 0.14）。星系的恒星成分的大小比射电连续谱辐射的范围大1.2倍（1.3）在z = 0.5（2），表明星星的形成在小半径处增强。银河系平均的星星形成率面密度（CRISSFR）与MS的距离成比例，除了一小部分MS星系（约10%）具有类似恒星爆发的CRISSFR。这些“隐藏的”恒星爆发可能经历了一个压缩阶段，由于磁盘的不稳定性和/或合并驱动的爆发的星星形成，这可能会或可能不会显着抵消星系从MS。因此，我们建议使用的MS的距离和距离，以更好地确定星系人口经历恒星爆发阶段。
To better constrain the physical mechanisms driving star formation, we present the first systematic study of the radio continuum size evolution of star-forming galaxies (SFGs) over the redshift range 0.35 < z < 2.25. We use the VLA COSMOS 3 GHz map (noise rms = 2.3 μJy beam−1, θbeam = 0.75 arcsec) to construct a mass-complete sample of 3184 radio-selected SFGs that reside on and above the main sequence (MS) of SFGs. We constrain the overall extent of star formation activity in galaxies by applying a 2D Gaussian model to their radio continuum emission. Extensive Monte Carlo simulations are used to validate the robustness of our measurements and characterize the selection function. We find no clear dependence between the radio size and stellar mass, M⋆, of SFGs with 10.5 ≲ log(M⋆/M⊙) ≲ 11.5. Our analysis suggests that MS galaxies are preferentially extended, while SFGs above the MS are always compact. The median effective radius of SFGs on (above) the MS of Reff = 1.5 ± 0.2 (1.0 ± 0.2) kpc remains nearly constant with cosmic time; a parametrization of the form Reff ∝ (1 + z)α yields a shallow slope of only α = −0.26 ± 0.08 (0.12 ± 0.14) for SFGs on (above) the MS. The size of the stellar component of galaxies is larger than the extent of the radio continuum emission by a factor ∼2 (1.3) at z = 0.5 (2), indicating star formation is enhanced at small radii. The galactic-averaged star formation rate surface density (ΣSFR) scales with the distance to the MS, except for a fraction of MS galaxies (≲10%) that harbor starburst-like ΣSFR. These “hidden” starbursts might have experienced a compaction phase due to disk instability and/or a merger-driven burst of star formation, which may or may not significantly offset a galaxy from the MS. We thus propose to use ΣSFR and distance to the MS in conjunction to better identify the galaxy population undergoing a starbursting phase.