We have developed a new SED fitting tool specialized for frontier redshift galaxies. It is a common case for high-z galaxies that the available data are restricted to rich optical to near-infrared photometry and few far-infrared (FIR) data deep enough to detect the faint object (e.g., HST/WFC3 + Spitzer/IRAC + ALMA). In such situation, one cannot perform a complicated modeling of dust emission in FIR regime. We then adopt simple treatment for the dust emission using empirical LIRG templates. Instead, we adopt a sophisticated and physically motivated modeling for stellar and nebular emission parts in rest-frame UV-to-optical regime. Our new code fits not only broad band photometry but also spectral emission line flux. There is an option to fit observed SED with two templates with different physical properties. Our new code, PANHIT, is now in public, and was already applied to some high-z frontier galaxies.

We calculate the spectral energy distribution of the first galaxies which contain pre-main-sequence stars by using the stellar evolution code Modules for Experiments in Stellar Astrophysics, the spectra model BT-Settl, and the stellar population synthesis code PEGASE. We calculate the galaxy spectral energy distribution for Salpeter Initial Mass Function. We find that very young first galaxies are bright also in mid-infrared, and the contribution of pre-main-sequence stars can be significant over 0.1 Myr after a star-formation episode.

We present results of our zoom-in cosmological hydrodynamic simulations of direct collapse (DC) to supermassive black hole (SMBH) seeds with radiative transfer (RT). The DC has been modeled in dark matter halos of ∼108M⊙, using adaptive mesh refinement (AMR) code Enzo. For the first time, the baryonic collapse has been followed down to 10−7 pc (∼0.01 AU) with on-the-fly RT and the flux-limited diffusion (FLD) approximation. We find a complex behavior involving accretion flow and associated outflows driven by the radiation force. The resulting gas dynamics around the central density peak differs profoundly from that in previous works which adopted adiabatic approximation in the core. The core forms with a photosphere at ∼1 AU, and its growth starts to saturate at ∼100M⊙. The unrelaxed core radiates intermittently near the Eddington luminosity, correlated with strong anisotropic outflows.

Optical properties of infrared-bright (IR-bright) dust-obscured galaxies (DOGs) are reported. DOGs are faint in optical but very bright in mid-IR, which are powered by active star formation (SF) or active galactic nucleus (AGN), or both. The DOGs is a candidate population that are evolving from a gas-rich merger to a quasar. By combining three catalogs of optical (Subaru Hyper Suprime-Cam), near-IR (VIKING), and mid-IR (ALLWISE), we have discovered 571 IR-bright DOGs. Using their spectral energy distributions, we classified the selected DOGs into the SF-dominated DOGs and the AGN-dominated DOGs. We found that the SF-dominated DOGs show a redder optical color than the AGN-dominated DOGs. Interestingly, some DOGs shows extremely blue color in optical (blue-excess DOGs: bluDOGs). A possible origin for this blue excess is either the leaked AGN light or stellar UV light from nuclear starbursts. The BluDOGs may be in the transition phase from obscured AGNs to unobscured AGNs.

We present the physical properties of Lyα emitters (LAEs) in a “DLA-concentrated regions” where there are 3 or more DLA within (50 Mpc)3 cubic box. We observed LAEs in a DLA-concentrated region at z = 2.3, the J1230+34 field, with Subaru/Suprime-Cam. In the 50 Mpc scale, we found no deferences in properties of LAEs such as Lyα luminosity function in the DLA-concentrated region compared to other fields at similar redshift. On the other hand, we found a ∼10 Mpc scale LAE overdensity around a strong DLA with NHI = 1021.08 cm−2.

In Panda et al.2018a, we constructed a refined sample from the original Shen et al.(2011) QSO catalog. Based on our hypothesis — the main driver of the Quasar Main Sequence is the maximum of the accretion disk temperature (TBBB) defined by the Big Blue Bump on the Spectral Energy Distribution (Panda et al.2017; Panda et al.2018b). We select the four extreme sources that have RFeII ⩾ 4.0 and use {CIGALE (Boquien et al.2018) to fit their multi—band photometric data. We also perform detailed spectral fitting including the Fe II pseudo—continuum (based on Śniegowska et al.2018)) to estimate and compare the value of RFEII. We show the dependence of FeII strength on changing metallicity.

We present results from high-resolution, zoom-in cosmological simulations to study the effect of feedback from galactic outflows on the physical and Lyα properties of high-redshift galaxies in highly overdense and normal environments at z >∼6. The Lyα properties have been obtained by post-processing the simulations with a Monte-Carlo radiative transfer (RT) code. Our results demonstrate that galactic outflows play an important role in regulating the growth of massive galaxies in overdense regions as well as the temperature and metallicity of the intergalactic medium. In particular, we find that galactic outflows are necessary to reproduce the observed Lyα luminosity functions as well as the apparent Lyα luminosity, line width and equivalent width distributions of luminous Lyα emitters at z ∼ 6.

Interstellar dust is traced by not only thermal emission but also scattered light. The scattered light spectrum observed from ultraviolet (UV) to near-infrared (IR) is useful to constrain some dust properties, such as size distribution, albedo, and composition. Milky Way Galaxy is a unique environment to observe the diffuse scattered light because we can extract it by removing the contribution of starlight. We have observed the UV to near-IR scattered light with space instruments, including Diffuse Infrared Background Experiment (DIRBE), Hubble Space Telescope (HST), and Multi-purpose Infra-Red Imaging System (MIRIS). The scattered light spectrum is marginally consistent with prediction from a recent dust model including carbonaceous and silicate grains with polycyclic aromatic hydrocarbon (PAH). Based on the MIRIS observation of a diffuse cloud, we compare the scattered light color with the dust model with or without grains larger than 1 micrometer. The result shows that the color is consistent with the model without the large grains, which is consistent with recent simulations of dust growth in low-density regions. However, some observations have shown the spectral excess at ∼ 0.6 micrometer wavelength, suggesting the presence of extended red emission (ERE) which cannot be explained by the conventional dust model.

The Coma supercluster is one of the largest, nearby (∼100h−1Mpc) gravitationally bound structures known in the universe. It comprises two large clusters of galaxies and several galaxy groups intersected by a complex network of filaments, providing the perfect laboratory for studying the evolution of galaxies in a range of ‘continuous’ environments. We characterised the different components of the environment to study the properties of galaxies in the optical and ultraviolet (UV) wavebands. Our analysis shows that galaxies experience accelerated evolution as they approach the spine of the filament, suggesting that the intermediate-density environment prevalent in the filaments can accelerate the evolution of galaxies.

We present a velocity of galactic outflows in star-forming galaxies at the highest redshift, z ∼ 6, so far studied with metal absorption lines. Absorption-line studies of galactic outflows need well-determined redshifts, but there are few strong emission lines in the observed-frame optical spectra of galaxies at high redshifts. In this work, we use the systemic redshifts determined by the ALMA [CII]158 μm emission lines. The sample consists of seven Lyman break galaxies at 5.1 < z < 5.7 whose Keck/DEIMOS and ALMA data are available in the archive. The outflow maximum velocity (νmax) is estimated by a fitting of line profiles to metal absorption lines in a composite spectrum. We find that νmax monotonically increases from z ∼ 0 to 6 and that νmax tightly correlates with the halo circular velocity estimated from the stellar mass.

We present a 4.7σ detection of the [OIII] 88 μm line in a gravitationally-lensed Lyman break galaxy, RXC J2248-ID3, using the Atacama Large Millimeter/submillimeter Array (ALMA). We did not detect [CII] 158 μm and rest-frame 90 μm dust continuum emission, suggesting that the bulk of the interstellar medium (ISM) is ionized. Our two-component SED model combining the previous Hubble Space Telescope (HST) data and new photometry obtained from Very Large Telescope (VLT), Spitzer and ALMA suggests the presence of young (∼2 Myr) and mature (∼600 Myr) stellar components with the metallicity of Z = 0.2Z⊙. Our findings are in contrast with previous results claiming a very young, metal-poor stellar component.

Recently huge amount of dust Mdust ≃ 106−7M⊙ in galaxies at z = 7–8 has been discovered by ALMA observations. The suggested timescale of the dust production was a few–several×108 yr, while the stellar mass was several × 109M⊙. This amount of dust cannot be easily explained only by a supply from supernovae if we consider the dust destruction by reverse shocks. We propose that these values can be consistently explained if we take into account the grain growth in the interstellar medium (ISM). This scenario successfully reproduces the evolution of the dust mass, as well as the SFR, and stellar mass simultaneously. We conclude that even at such an early epoch of the Universe, the dust grain growth in the ISM plays a significant role in galaxies.

We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN), utilizing the Monte Carlo simulation for Astrophysics and Cosmology framework (MONACO: Odaka et al.2016). The geometry of the torus is the same as that in Nenkova et al. (2008), which assumes a power law distribution of clumps in the radial direction and a normal distribution in the elevation direction. We apply our model to the broadband X-ray spectrum of the Circinus galaxy observed with XMM-Newton, Suzaku, and NuSTAR. Our model can well reproduce the observed X-ray spectrum, yielding a hydrogen column density along the line-of-sight ${N_{\rm{H}}^{\rm{LOS}}} = 4.86_{ - 0.04}^{ + 0.07} \times {10^{24}}$ cm−2 and a torus angular width ${sigma = 14.7_{ - 0.39}^{ + 0.44}}$ degree.

The measurement of Hα luminosity for large numbers of galaxies is important to investigate recent star formation history of galaxies. With SED fitting that includes emission line templates, we extract individual galaxy Hα luminosities from broad-band photometry. We compare Hα luminosity function with the result of a narrow-band survey, HiZELS, and find there are more luminous galaxies in Hα than previously reported. As a result, our derived star formation rate density at z ∼ 2.3 turns out to be 2.2 times higher than previous studies. Most of the offset in the results can be explained by missing Hα in the HiZELS photometric aperture and different methods for dust extinction correction.

Studying the density profiles of galaxy groups offers an important insight on how large-scale structure in the Universe formed and evolved, since galaxy groups bridge the gap between individual galaxies and galaxy clusters. We aim to probe the total density profile of the galaxy group that is gravitational lensing HELMS18, a submillimeter galaxy at z = 2.39 from the Herschel’s HerMES Large Mode Survey (HELMS), by combining strong gravitational lensing with kinematics of the centrally-located galaxies and kinematics of the group members. We will use high-resolution data of HELMS18 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and multi-object spectroscopic data of the group members from Gemini-GMOS. Our final goal is to combine these observations to probe the stellar and dark matter density profiles and to build a complete description of this galaxy group.

Magnetic field plays an important role in star formation and galaxy evolution. Previous studies discussed about the origin of magnetic field and its effect to the environment. With the recent advancement of supercomputers, adding the magnetic field to a cosmological hydrodynamic simulations only become feasible. In this proceeding, we present the results of high-resolution magneto-hydrodynamic simulation with GIZMO and compare our simulation result with the previous literature and the observations.

We investigate the stellar population of star-forming galaxies at z ∼ 4 by focusing on their slope of rest-frame ultraviolet continuum called UV spectral slope β. We analyze the sample of bright Lyman Break Galaxies (LBGs) with Subaru/i′≤26.0in the Subaru/XMM-Newton Deep Survey field. Our detailed SED fitting analysis indicates that the LBGs with observed UV slope > −1.7, , Av > 1.0, and intrinsic UV slope < −2.5 are the intrinsically active star-forming galaxies with star formation rates larger than a few × 102 M⊙yr−1. A significant fraction of the UV-selected LBGs at z ∼ 4 is on-going active and dust obscured star-forming galaxies.