分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Galaxy formation theories predict that galaxy shapes and angular momenta have intrinsic alignments (IA) with the cosmic web, which provides an observational test of various theories, and is important to quantify as a nuisance parameter for weak lensing. We study galaxy IA in the IllustrisTNG suite of hydrodynamical simulations at redshifts 1 and 2, finding that alignment trends are consistent with previous studies. However, we find that the magnitude of the spin alignment signal is $\sim 2.4 \times$ weaker than seen in previous studies of the Horizon-AGN simulation, suggesting that IA may have significant dependence on subgrid physics. Based on IllustrisTNG, we then construct mock observational spectroscopic surveys that can probe shape-cosmic web IA at $z \sim 1-2$, modeled on the low-$z$ galaxy redshift and IGM tomography surveys on the upcoming Subaru Prime Focus Spectrograph Galaxy Evolution (PFS GE) survey. However, even over box sizes of $L=205 h^{-1} \mathrm{Mpc}$, we find that global anisotropies induce a sample variance in the 2D projected IA signal that depend on the projected direction -- this induces significant errors in the observed alignment. We predict a $5.3\sigma$ detection of IlustrisTNG's shape IA signal at $z \sim 1$ from Subaru PFS GE, although a detection would be challenging at $z \sim 2$. However, a rough rescaling of the relative IA signal strengths between the TNG and HorizonAGN simulations suggests that PFS GE should be able to constrain the latter's stronger signal.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shenli Tang
John D. Silverman
Xuheng Ding
Junyao Li
Khee-Gan Lee
Michael A. Strauss
Andy Goulding
Malte Schramm
Lalitwadee Kawinwanichakij
J. Xavier Prochaska
Joseph F. Hennawi
Masatoshi Imanishi
Kazushi Iwasawa
Yoshiki Toba
Issha Kayo
Masamune Oguri
Yoshiki Matsuoka
Kohei Ichikawa
Tilman Hartwig
Nobunari Kashikawa
摘要： We report on a spectroscopic program to search for dual quasars using Subaru Hyper Suprime-Cam (HSC) images of SDSS quasars which represent an important stage during galaxy mergers. Using Subaru/FOCAS and Gemini-N/GMOS, we identify three new physically associated quasar pairs having projected separations less than 20 kpc, out of 26 observed candidates. These include the discovery of the highest redshift ($z=3.1$) quasar pair with a separation $<$ 10 kpc. Based on the sample acquired to date, the success rate of identifying physically associated dual quasars is $19\%$ when excluding stars based on their HSC colors. Using the full sample of six spectroscopically confirmed dual quasars, we find that the black holes in these systems have black hole masses ($M_{BH} \sim 10^{8-9}M_{\odot}$) similar to single SDSS quasars as well as their bolometric luminosities and Eddington ratios. We measure the stellar mass of their host galaxies based on 2D image decomposition of the five-band ($grizy$) optical emission and assess the mass relation between supermassive black holes (SMBHs) and their hosts. Dual SMBHs appear to have elevated masses relative to their host galaxies. Thus mergers may not necessarily align such systems onto the local mass relation, as suggested by the Horizon-AGN simulation. This study suggests that dual luminous quasars are triggered prior to the final coalescence of the two SMBHs, resulting in early mass growth of the black holes relative to their host galaxies.
点击量
待评议
点击量
下载量
评论
