分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jack E. Birkin
Ian Smail
A. M. Swinbank
Fang Xia An
S. C. Chapman
Chian-Chou Chen
C. J. Conselice
U. Dudzevičiūtė
D. Farrah
B. Gullberg
Y. Matsuda
A. Puglisi
E. Schinnerer
D. Scott
J. L. Wardlow
P. van der Werf
摘要： We present spatially resolved kinematics of 31 ALMA-identified dust-obscured star-forming galaxies (DSFGs) at $z\sim$1.3-2.6, as traced by H$\alpha$ emission using VLT/KMOS near-infrared integral field spectroscopy from our on-going Large Programme ''KMOS-ALMA Observations of Submillimetre Sources'' (KAOSS). We derive H$\alpha$ rotation curves and velocity dispersion profiles for the DSFGs. Of the 31 sources with bright, spatially extended H$\alpha$ emission, 25 display rotation curves that are well fit by a Freeman disc model, enabling us to measure a median inclination-corrected velocity at 2.2$R_{\rm d}$ of $v_{\rm rot}$ = 190 $\pm$ 30 kms$^{-1}$ and a median intrinsic velocity dispersion of $\sigma_0$ = 87 $\pm$ 6 kms$^{-1}$ for these $\textit{disc-like}$ sources. By comparison with less actively star-forming galaxies, KAOSS DSFGs are both faster rotating and more turbulent, but have similar $v_{\rm rot}/\sigma_0$ ratios, median 2.4 $\pm$ 0.5. We suggest that $v_{\rm rot}/\sigma_0$ alone is insufficient to describe the kinematics of DSFGs, which are not kinematically ''cold'' discs, and that the individual components $v_{\rm rot}$ and $\sigma_0$ indicate that they are in fact turbulent, but rotationally supported systems in $\sim$50 per cent of cases. This turbulence may be driven by star formation or mergers/interactions. We estimate the normalisation of the stellar Tully-Fisher relation (sTFR) for the disc-like DSFGs and compare it with local studies, finding no evolution at fixed slope between $z\sim$2 and $z\sim$0. Finally, we use kinematic estimates of DSFG halo masses to investigate the stellar-to-halo mass relation, finding our sources to be consistent with shock heating and strong feedback which likely drives the declining stellar content in the most massive halos.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Protoclusters are important for studying how halo mass and stellar mass assemble in the early universe. Finding signposts of such over-dense regions is a popular method to identify protocluster candidates. Hyperluminous infrared galaxies (HLIRGs), are expected to reside in overdense regions with massive halos. We study the Mpc-scale environment of the largest HLIRG sample to date and investigate whether they predominantly live in overdense regions. We first explore the surface density of Herschel 250 $\mu$m sources around HLIRGs and compare with that around random positions. Then, we compare the spatial distribution of neighbours around HLIRGs with that around randomly selected galaxies using a deep IRAC-selected catalogue with good-quality photometric redshifts. We also use a redshift-matched quasar sample and submillimeter galaxy (SMG) sample to validate our method, as previous clustering studies have measured the host halo masses of these populations. Finally, we adopt a Friends of Friends (FOF) algorithm to seek (proto)clusters that host HLIRGs. We find that HLIRGs tend to have more bright star-forming neighbours (with 250 $\mu$m flux density >10 mJy) within 100$\arcsec$ projected radius than a random galaxy at a 3.7$\sigma$ significance. In our 3D analysis, we find relatively weak excess of IRAC-selected sources within 3 Mpc around HLIRGs compared with random galaxy neighbours, mainly influenced by photometric redshift uncertainty and survey depth. We find a more significant difference (at a 4.7$\sigma$ significance) in the number of Low Frequency Array (LOFAR)-detected neighbours in the deepest EN1 field. HLIRGs at 3 < z < 4 show stronger excess compared to HLIRGs at 2 < z < 3, consistent with cosmic downsizing. Finally, we select and present a list of 30 most promising protocluster candidates for future follow-up observations.
点击量
待评议
点击量
下载量
评论
