您选择的条件: Satoshi Kikuta
  • The JCMT SCUBA-2 Survey of the James Webb Space Telescope North Ecliptic Pole Time-Domain Field

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The James Webb Space Telescope Time-Domain Field (JWST-TDF) is an $\sim$14$'$ diameter field near the North Ecliptic Pole that will be targeted by one of the JWST Guaranteed Time Observations programs. Here, we describe our James Clerk Maxwell Telescope SCUBA-2 850 $\mu$m imaging of the JWST-TDF and present the submillimeter source catalog and properties. We also present a catalog of radio sources from Karl J. Jansky Very Large Array 3 GHz observations of the field. These observations were obtained to aid JWST's study of the dust-obscured galaxies that contribute significantly to the cosmic star formation at high redshifts. Our deep 850 $\mu$m map covers the JWST TDF at a noise level of $\sigma_{850}$ = 1.0 mJy beam$^{-1}$, detecting 83/31 sources in the main/supplementary signal-to-noise ratio (S/N $>$ 4 / S/N = 3.5 - 4) sample respectively. The 3 GHz observations cover a 24$'$ diameter field with a 1 $\sigma$ noise of 1$\mu$Jy beam$^{-1}$ at a 0$.\!\!^{\prime\prime}$7 FWHM. We identified eighty-five 3 GHz counterparts to sixty-six 850 $\mu$m sources and then matched these with multiwavelength data from the optical to the mid-infrared wave bands. We performed spectral energy distribution fitting for 61 submillimeter galaxies (SMGs) matched with optical/near-infrared data, and found that SMGs at S/N $>$ 4 have a median value of $z_{phot} = $2.22 $\pm$ 0.12, star formation rates of 300 $\pm$ 40 M$_{\odot}\,{\rm yr^{-1}}$ (Chabrier initial mass function), and typical cold dust masses of 5.9 $\pm$ 0.7 $ \times$ 10$^{8} $M$_{\odot}$, in line with bright SMGs from other surveys. The large cold dust masses indicate correspondingly large cool gas masses, which we suggest are a key factor necessary to drive the high star formation rates seen in this population

  • UV & Ly$\alpha$ halos of Ly$\alpha$ emitters across environments at z=2.84

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We present UV and Ly$\alpha$ radial surface brightness (SB) profiles of Ly$\alpha$ emitters (LAEs) at $z=2.84$ detected with the Hyper Suprime-Cam (HSC) on the Subaru Telescope. The depth of our data, together with the wide field coverage including a protocluster, enable us to study the dependence of Ly$\alpha$ halos (LAHs) on various galaxy properties, including Mpc-scale environments. UV and Ly$\alpha$ images of 3490 LAEs are extracted, and stacking the images yields SB sensitivity of $\sim1\times10^{-20}\mathrm{~erg~s^{-1}~cm^{-2}~arcsec^{-2}}$ in Ly$\alpha$, reaching the expected level of optically thick gas illuminated by the UV background at $z\sim3$. Fitting of the two-component exponential function gives the scale-lengths of $1.56\pm0.01$ and $10.4\pm0.3$ pkpc. Dividing the sample according to their photometric properties, we find that while the dependence of halo scale-length on environment outside of the protocluster core is not clear, LAEs in the central regions of protoclusters appear to have very large LAHs which could be caused by combined effects of source overlapping and diffuse Ly$\alpha$ emission from cool intergalactic gas permeating the forming protocluster core irradiated by active members. For the first time, we identify ``UV halos'' around bright LAEs which are probably due to a few lower-mass satellite galaxies. Through comparison with recent numerical simulations, we conclude that, while scattered Ly$\alpha$ photons from the host galaxies are dominant, star formation in satellites evidently contributes to LAHs, and that fluorescent Ly$\alpha$ emission may be boosted within protocluster cores at cosmic noon and/or near bright QSOs.

  • MAMMOTH-Subaru IV. Large Scale Structure and Clustering Analysis of Ly$\alpha$ Emitters and Ly$\alpha$ Blobs at $z=2.2-2.3$

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We report the large scale structure and clustering analysis of Ly$\alpha$ emitters (LAEs) and Ly$\alpha$ blobs (LABs) at $z=2.2-2.3$. Using 3,341 LAEs, 117 LABs, and 58 bright (Ly$\alpha$ luminosity $L_{\rm Ly\alpha}>10^{43.4}$ erg s$^{-1}$) LABs at $z=2.2-2.3$ selected with Subaru/Hyper Suprime-Cam (HSC), we calculate the LAE overdensity to investigate the large scale structure at $z=2$. We show that 74% LABs and 78% bright LABs locate in overdense regions, which is consistent with the trend found by previous studies that LABs generally locate in overdense regions. We find that one of our 8 fields dubbed J1349 contains $39/117\approx33\%$ of our LABs and $22/58\approx38\%$ of our bright LABs. A unique and overdense $24'\times12'$ ($\approx 40\times20$ comoving Mpc$^2$) region in J1349 has 12 LABs (8 bright LABs). By comparing to SSA22 that is one of the most overdense LAB regions found by previous studies, we show that the J1349 overdense region contains $\geq 2$ times more bright LABs than the SSA22 overdense region. We calculate the angular correlation functions (ACFs) of LAEs and LABs in the unique J1349 field and fit the ACFs with a power-law function to measure the slopes. The slopes of LAEs and LABs are similar, while the bright LABs show a $\approx 2$ times larger slope suggesting that bright LABs are more clustered than faint LABs and LAEs. We show that the amplitudes of ACFs of LABs are higher than LAEs, which suggests that LABs have a $\approx 10$ times larger galaxy bias and field-to-field variance than LAEs. The strong field-to-field variance is consistent with the large differences of LAB numbers in our 8 fields.

  • MAMMOTH-Subaru IV. Large Scale Structure and Clustering Analysis of Ly$\alpha$ Emitters and Ly$\alpha$ Blobs at $z=2.2-2.3$

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We report the large scale structure and clustering analysis of Ly$\alpha$ emitters (LAEs) and Ly$\alpha$ blobs (LABs) at $z=2.2-2.3$. Using 3,341 LAEs, 117 LABs, and 58 bright (Ly$\alpha$ luminosity $L_{\rm Ly\alpha}>10^{43.4}$ erg s$^{-1}$) LABs at $z=2.2-2.3$ selected with Subaru/Hyper Suprime-Cam (HSC), we calculate the LAE overdensity to investigate the large scale structure at $z=2$. We show that 74% LABs and 78% bright LABs locate in overdense regions, which is consistent with the trend found by previous studies that LABs generally locate in overdense regions. We find that one of our 8 fields dubbed J1349 contains $39/117\approx33\%$ of our LABs and $22/58\approx38\%$ of our bright LABs. A unique and overdense $24'\times12'$ ($\approx 40\times20$ comoving Mpc$^2$) region in J1349 has 12 LABs (8 bright LABs). By comparing to SSA22 that is one of the most overdense LAB regions found by previous studies, we show that the J1349 overdense region contains $\geq 2$ times more bright LABs than the SSA22 overdense region. We calculate the angular correlation functions (ACFs) of LAEs and LABs in the unique J1349 field and fit the ACFs with a power-law function to measure the slopes. The slopes of LAEs and LABs are similar, while the bright LABs show a $\approx 2$ times larger slope suggesting that bright LABs are more clustered than faint LABs and LAEs. We show that the amplitudes of ACFs of LABs are higher than LAEs, which suggests that LABs have a $\approx 10$ times larger galaxy bias and field-to-field variance than LAEs. The strong field-to-field variance is consistent with the large differences of LAB numbers in our 8 fields.