HST/WFC3对0<z<2质量星系由内向外生长的确认及其z~3恒星形成祖先的鉴别
HST/WFC3 Confirmation of the Inside-Out Growth of Massive Galaxies at 0<z<2 and Identification of their Star Forming Progenitors at z~3
摘要：
我们研究了大质量星系的结构演化，通过将祖先星系和后代星系联系在一个常数累积数密度nc = 1.4 × 10 ^{-4} Mpc^{-3}到z~3上。通过将Sersic曲线拟合到高分辨率CANDELS HST WFC 3 J_{125}和H_{160}成像（在UKIDSS-UDS中1<z<3）以及ACS I_{814}成像（在COSMOS中0.25<z<1）来测量结构参数。在一个给定的红移，我们选择的HST波段，最密切的采样一个共同的休息帧波长，以尽量减少星系中的颜色梯度的系统。当n c固定时，星系的恒星质量从z~3到z~0增长~3倍。星系的大小演化是复杂的：星系的大小从z~3到z~2大致保持不变，然后迅速增长到较低的红移。表面质量密度分布的演变表明，在r<2 kpc时，大部分质量在z~2时就位，并且大部分新的质量增长发生在更大的半径处。这种由内而外的质量增长是导致后代向低红移方向发展的更大尺寸和更高的Sersic指数的原因。在z<2时，有效半径随恒星质量的变化为r_e M^{2.0}，这与发现无耗散小合并是尺寸演化的关键驱动力的情景一致。z~3处的祖先星可能是r_e~ 2kpc的恒星形成盘，这是由于它们的Sersic指数低（n~1），中轴比b/a低（0.52），在U-V-V-J图上位于恒星形成区。到z~1.5时，许多这些恒星形成盘消失了，产生了紧凑的静止星系。朝向较低的红移，这些星系继续聚集在更大的半径质量，并成为当地的椭圆主导的质量函数在本时代的高质量端。
英文摘要：
We study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n_c=1.4x10^{-4} Mpc^{-3} to z~3. Structural parameters were measured by fitting Sersic profiles to high resolution CANDELS HST WFC3 J_{125} and H_{160} imaging in the UKIDSS-UDS at 1<z<3 and ACS I_{814} imaging in COSMOS at 0.25<z<1. At a given redshift, we selected the HST band that most closely samples a common rest-frame wavelength so as to minimize systematics from color gradients in galaxies. At fixed n_c, galaxies grow in stellar mass by a factor of ~3 from z~3 to z~0. The size evolution is complex: galaxies appear roughly constant in size from z~3 to z~2 and then grow rapidly to lower redshifts. The evolution in the surface mass density profiles indicates that most of the mass at r<2 kpc was in place by z~2, and that most of the new mass growth occurred at larger radii. This inside-out mass growth is therefore responsible for the larger sizes and higher Sersic indices of the descendants toward low redshift. At z<2, the effective radius evolves with the stellar mass as r_e M^{2.0}, consistent with scenarios that find dissipationless minor mergers to be a key driver of size evolution. The progenitors at z~3 were likely star-forming disks with r_e~2 kpc, based on their low Sersic index of n~1, low median axis ratio of b/a~0.52, and typical location in the star-forming region of the U-V versus V-J diagram. By z~1.5, many of these star-forming disks disappeared, giving rise to compact quiescent galaxies. Toward lower redshifts, these galaxies continued to assemble mass at larger radii and became the local ellipticals that dominate the high mass end of the mass function at the present epoch.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
