Search

Intensity mapping of 21-cm line by several radio telescope experiments will probe the large-scale structure of the Universe in the post-reionization epoch. It requires a theoretical framework of neutral hydrogen (HI) clustering, such as modelling of HI power spectrum for Baryon Acoustic Oscillations (BAO) analysis. We propose a new method for reconstructing the HI map from dark matter distribution using N-body simulations. Several studies attempt to compute the HI power spectrum with N-body simulations by pasting HI gas at the dark matter halo centre, assuming the relation between the halo and HI masses. On the other hand, the method proposed in this paper reproduces the HI power spectrum from simulated dark matter distribution truncated at specific scales from the halo centre. With this method, the slope of HI power spectrum is reproduced well at the BAO scales, $k, 12 pages, 11 figures, Submitted to MNRAS

Oral and systemic health are linked, with bad Streptococcus mutans (S. mutans) linked to increased risk of intracerebral micro-bleeding and heart disease, and Porphyromonas gingivalis (P. gingivalis) reports of links between periodontal disease and non-alcoholic steatohepatitis (NASH), diabetes, rheumatoid arthritis, Alzheimer's disease, premature birth, and underweight birth. Dr Kentaro Nagamine, Department of Clinical Nutrition, Hiroshima International University, Japan, was involved in the loop-mediated isothermal amplification (LAMP) method and is applying this to oral health, developing primers for LAMP of S. mutans and P. gingivalis and has also developed methods to culture oral bacteria. In one project, he is developing a detection kit for bad S. mutans (cnm gene positive S. mutans). The method he is developing is simple and effective compared to existing methods that tend to be complicated and lengthy. It involves taking a saliva sample, which is then cultured and put into the LAMP reaction solution. Then, the target gene is amplified and gene amplification is seen, this confirms that the bacteria is present. Not only can a result be obtained within two days, but the method also has the ability to amplify multiple types of bacteria. Nagamine is collaborating with a dental clinic that is utilising his method and, in the future, he hopes it can be used for dental examinations in numerous countries and regions, particularly in developing countries.

Advanced glycation end-products (AGEs) are produced by the non-enzymatic reaction of sugars with proteins. It has been revealed that glyceraldehyde-derived toxic AGEs (TAGE) are elevated in the serum of non-alcoholic steatohepatitis (NASH) patients. NASH causes liver fibrosis and progresses to cirrhosis and hepatocellular carcinoma. However, the impact of TAGE in liver fibrosis caused by extracellular matrix accumulation remains poorly understood. In this study, we examined the effect of TAGE on the activation of hepatic stellate cells that are involved in liver fibrosis. LX-2 cells treated with transforming growth factor-β1 (TGF-β1) significantly reduced cell viability by apoptosis. However, the decrease in cell viability with TGF-β1 treatment was significantly suppressed by TAGE co-treatment. The levels of α-smooth muscle actin (α-SMA) and platelet-derived growth factor (PDGF)-Rβ and its ligand PDGF-B were increased in LX-2 cells following TGF-β1 treatment, suggesting that these cells were activated; however, these increases were unaffected by TAGE co-treatment. Moreover, collagen I level was increased with TGF-β1 treatment, and this increase was further increased by TAGE co-treatment. These results suggested that the suppression of apoptosis in activated LX-2 cells by TGF-β1 and TAGE co-treatment is related to an increase in the production of the extracellular matrix such as collagen I. Therefore, it was suggested that TAGE might aggravate the liver fibrosis of chronic hepatitis, such as NASH.

The primordial He abundance $Y_\mathrm{P}$ is a powerful probe of cosmology. Currently, $Y_\mathrm{P}$ is best determined by observations of metal-poor galaxies, while there are only a few known local extremely metal-poor ($, Comment: 22 pages, 9 figures, accepted for publication in ApJ

Understanding the evolution of dust and molecular hydrogen (H$_2$) is a critical aspect of galaxy evolution, as they affect star formation and the spectral energy distribution of galaxies. We use the $N$-body/smoothed-particle-hydrodynamics code {\sc Gadget-4} to compute the evolution of dust and H$_2$ in a suite of numerical simulations of an isolated Milky-Way-like galaxy. The evolution of the full grain size distribution (GSD) is solved by sampling the grain size on a logarithmically spaced grid with 30 bins. The evolution of a primordial chemistry network with twelve species is solved consistently with the hydrodynamic evolution of the system, including star formation, metal and energy ejections from stars into the interstellar medium through supernova feedback and stellar winds. The formation model for H$_2$ considers the GSD and photo-dissociation through the UV radiation of young stars. We identify the processes needed for producing a sizeable amount of H$_2$, verify that the resulting star formation law in the later stages of galaxy evolution is consistent with observations of local spirals, and show that our model manages to produce a galactic molecular gas fraction in line with observations of Milky-Way-like galaxies. We stress the importance of the co-evolution of the GSD and H$_2$, as models assuming a fixed MRN shape for the GSD overestimate the production of H$_2$ in regimes where the dust abundance is dominated by large grains and underestimate it in the regime where the dust is dominated by small grains, both of which are realized in simulations of dust evolution., Accepted for publication in MNRAS. 16 pages, 13 figures

Feedback from supernovae (SNe) is an essential mechanism that self-regulates the growth of galaxies, and a better model of SN feedback is still needed in galaxy formation simulations. In the first part of this paper, using an Eulerian hydrodynamic code Athena++, we find universal scaling relations for the time evolution of momentum and radius for a superbubble, when the momentum and time are scaled by those at the shell-formation time. In the second part of this paper, we develop an SN feedback model based on the Athena++ simulation results utilizing Voronoi tessellation around each star particle, and implement it into the GADGET3-Osaka smoothed particle hydrodynamic code. Our feedback model was demonstrated to be isotropic and conservative in terms of energy and momentum. We examined the mass/energy/metal loading factors and find that our stochastic thermal feedback model produced galactic outflow that carries metals high above the galactic plane but with weak suppression of star formation. Additional mechanical feedback further suppressed star formation and brought the simulation results in better agreement with the observations of the Kennicutt--Schmidt relation, with all the results being within the uncertainties of observed data. We argue that both thermal and mechanical feedback are necessary for the SN feedback model of galaxy evolution when an individual SN bubble is unresolved., 36 pages, 22 figures, accepted for publication in The Astrophysical Journal Supplement Series. Movies available at https://www.yurioku.com/research/

We compute the evolution of the grain size distribution (GSD) in a suite of numerical simulations of an isolated Milky-Way-like galaxy using the $N$-body/smoothed-particle-hydrodynamics code {\sc Gadget-4}. The full GSD is sampled on a logarithmically spaced grid with 30 bins, and its evolution is calculated self-consistently with the hydrodynamical and chemical evolution of the galaxy using a state-of-the-art star formation and feedback model. In previous versions of this model, the GSD tended to be slightly biased towards larger grains and the extinction curve had a tendency to be flatter than the observations. This work addresses these issues by considering the diffusion of dust and metals through turbulence on subgrid scales and introducing a multi-phase subgrid model that enables a smoother transition from diffuse to dense gas. We show that diffusion can significantly enhance the production of small grains and improve the agreement with the observed dust extinction curve in the Milky Way., Comment: Accepted for publication in MNRAS. 20 pages, 23 figures

RAS guanyl nucleotide-releasing proteins (RASGRPs) are important proteins that act as guanine nucleotide exchange factors, which activate small GTPases and function as molecular switches for intracellular signals. The RASGRP family is composed of RASGRP1–4 proteins and activates the small GTPases, RAS and RAP. Among them, RASGRP2 has different characteristics from other RASGRPs in that it targets small GTPases and its localizations are different. Many studies related to RASGRP2 have been reported in cells of the blood cell lineage. Furthermore, RASGRP2 has also been reported to be associated with Huntington’s disease, tumors, and rheumatoid arthritis. In addition, we also recently reported RASGRP2 expression in vascular endothelial cells, and clarified the involvement of xenopus Rasgrp2 in the vasculogenesis process and multiple signaling pathways of RASGRP2 in human vascular endothelial cells with stable expression of RASGRP2. Therefore, this article outlines the existing knowledge of RASGRP2 and focuses on its expression and role in vascular endothelial cells, and suggests that RASGRP2 functions as a protective factor for maintaining healthy blood vessels.

Recent discoveries of high-redshift galaxies have revealed the diversity of their physical properties, from normal star-forming galaxies to starburst galaxies. To understand the properties of these observed galaxies, it is crucial to understand the star formation (SF) history, and the radiation properties associated with the SF activity. Here we present the results of cosmological hydrodynamic simulations with zoom-in initial conditions, and show the formation of the first galaxies and their evolution towards observable galaxies at z = 6. In addition, we show their multi-wavelength radiative properties. We find that star formation occurs intermittently due to supernova (SN) feedback at z > 10, and their radiation properties rapidly change with time. We suggest that the first galaxies are bright at UV wavelengths just after the starburst phase, and become extended Lyman-alpha sources. We also show that massive galaxies cause dusty starburst and become bright at infrared wavelengths.

Recent observations have successfully detected UV or infrared flux from galaxies at the epoch of reionization. However, the origin of their radiative properties has not been fully understood yet. Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present theoretical predictions of multi-wavelength radiative properties of the first galaxies at z=6-15. We find that most of the gas and dust are ejected from star-forming regions due to supernova (SN) feedback, which allows UV photons to escape. We show that the peak of SED rapidly shifts between UV and infrared wavelengths on a timescale of 100 Myr due to intermittent star formation and feedback. When dusty gas covers the star-forming regions, the galaxies become bright in the observed-frame sub-millimeter wavelengths. In addition, we find that the escape fraction of ionizing photons also changes between 1-40% at z>10. The mass fraction of HII region changes with the star formation history, resulting in the fluctuations of metal lines and Lyman-alpha line luminosities. In the starbursting phase of galaxies with the halo mass $\sim 10^{11}\,{\rm M_{\odot}}$ ($10^{12}\,{\rm M_{\odot}}$), the simulated galaxy has $L_{\rm [O\,III]} \sim 10^{42}\, (10^{43})\, {\rm erg\,s^{-1}}$, which is consistent with the observed star-forming galaxies at z>7. Our simulations suggest that deep [C II] observation with ALMA can trace the distribution of neutral gas extending over $\sim 20$ physical kpc. We also find that the luminosity ratio $L_{\rm [O\,III]}/L_{\rm [C\,II]}$ decreases with bolometric luminosity due to metal enrichment. Our simulations show that the combination of multi-wavelength observations by ALMA and JWST will be able to reveal the multi-phase ISM structure and the transition from starbursting to outflowing phases of high-z galaxies., 5 pages, 4 figures, Proceedings IAU Symposium No. 352 "Uncovering early galaxy evolution in the ALMA and JWST era", Viana do Castelo, Portugal, June 2019

We report that Ly$\alpha$-emitting galaxies (LAEs) may not faithfully trace the cosmic web of neutral hydrogen (HI), but their distribution is likely biased depending on the viewing direction. We calculate the cross-correlation (CCF) between galaxies and Ly$\alpha$ forest transmission fluctuations on the near and far sides of the galaxies separately, for three galaxy samples at $z\sim2$: LAEs, [OIII] emitters (O3Es), and continuum-selected galaxies. We find that only LAEs have anisotropic CCFs, with the near side one showing lower signals up to $r=3-4~h^{-1}$ comoving Mpc. This means that the average HI density on the near side of LAEs is lower than that on the far-side by a factor of $2.1$ under the Fluctuating Gunn-Peterson Approximation. Mock LAEs created by assigning Ly$\alpha$ equivalent width ($EW_\text{Ly$\alpha$}^\text{obs}$) values to O3Es with an empirical relation also show similar, anisotropic CCFs if we use only objects with higher $EW_\text{Ly$\alpha$}^\text{obs}$ than a certain threshold. These results indicate that galaxies on the far side of a dense region are more difficult to be detected ("hidden") in Ly$\alpha$ because Ly$\alpha$ emission toward us is absorbed by dense neutral hydrogen. If the same region is viewed from a different direction, a different set of LAEs will be selected as if galaxies are playing hide-and-seek using HI gas. Care is needed when using LAEs to search for overdensities., Comment: 10 pages, 5 figures, Accepted for publication on ApJL

Advanced glycation end-products (AGEs) are formed by the non-enzymatic reaction of sugars and proteins. Among the AGEs, glyceraldehyde-derived toxic AGEs (TAGE) are associated with various diseases, including diabetic complications such as diabetic retinopathy (DR). The risk of developing DR is strongly associated with poor glycemic control, which causes AGE accumulation and increases AGE-induced vascular permeability. We previously reported that Ras guanyl nucleotide releasing protein 2 (RasGRP2), which activates small G proteins, may play an essential role in the cell response to toxicity when exposed to various factors. However, it is not known whether RasGRP2 prevents the adverse effects of TAGE in vascular endothelial cells. This study observed that TAGE enhanced vascular permeability by disrupting adherens junctions and tight junctions via complex signaling, such as ROS and non-ROS pathways. In particular, RasGRP2 protected adherens junction disruption, thereby suppressing vascular hyper-permeability. These results indicate that RasGRP2 is an essential protective factor of vascular permeability and may help develop novel therapeutic strategies for AGE-induced DR.

Porphyromonas gingivalis fimbrillin (fimA) type II and IV, the definitive factors for periodontitis, are also found to be associated with systemic diseases. To detect the fimA type II and IV genes easily and rapidly, we used the loop-mediated isothermal amplification (LAMP) method. The LAMP method showed high specificity as DNA from the P. gingivalis HW24D1 strain could only be amplified by the type II-specific primers and that from the W83 strain could only be amplified by the type IV-specific primers. Pathogens, namely, Streptococcus sobrinus, S. mutans, and Candida species, lack the type II and IV genes, and hence, were not detected by the LAMP reaction. Both bacterial cells and purified DNA could be used in the LAMP reaction. The LAMP reaction was highly sensitive and both type II and type IV genes could be detected in 1000 DNA molecules. In the bacterial suspensions of HW24D1 and W83 strains, type II and type IV genes, respectively, could be detected in 100 bacterial cells. We examined the type II and type IV genes in the dental plaques from 22 P. gingivalis-positive patients using the LAMP method. Only one person was found to be positive for the type II gene (4.5%). For the type IV gene, 3 positive cases (13.6%) were identified. Moreover, type II and type IV genes could be detected simultaneously using a multiplex amplification primer of fimA type II and type IV, under visible light. Thus, we established a selective and easy method to detect P. gingivalis fimA type II and IV genes using LAMP.

he correlation between neutral hydrogen (H i) in the intergalactic medium (IGM) and galaxies attracts great interest. We select four fields that include several coherently strong Lyα absorption systems at z ∼ 2.2 detected using background quasars from the whole SDSS/(e) Baryon Oscillation Spectroscopic Survey (BOSS) database. Deep narrowband and g-band imaging are performed using the Hyper Suprime-Cam on the Subaru Telescope. We select 2642 Lyα emitter (LAE) candidates at z = 2.177 ± 0.023 down to the Lyα luminosity of LLyα ≈ 2 × 1042 erg s−1 to construct the galaxy overdensity maps, covering an effective area of 5.39 deg2. Combining the sample with the Lyα absorption estimated from 64 (e) BOSS quasar spectra, we find a moderate to strong correlation between the LAE overdensity δLAE and the effective optical depth τLoS in lines of sight, with P value = 0.09% or

The habitual intake of large amounts of sugar, which has been implicated in the onset/progression of lifestyle-related diseases (LSRD), induces the excessive production of glyceraldehyde (GA), an intermediate of sugar metabolism, in neuronal cells, hepatocytes, and cardiomyocytes. Reactions between GA and intracellular proteins produce toxic advanced glycation end-products (toxic AGEs, TAGE), the accumulation of which contributes to various diseases, such as Alzheimer’s disease, non-alcoholic steatohepatitis, and cardiovascular disease. The cellular leakage of TAGE affects the surrounding cells via the receptor for AGEs (RAGE), thereby promoting the onset/progression of LSRD. We demonstrated that the intracellular accumulation of TAGE triggered numerous cellular disorders, and also that TAGE leaked into the extracellular space, thereby increasing extracellular TAGE levels in circulating fluids. Intracellular signaling and the production of reactive oxygen species are affected by extracellular TAGE and RAGE interactions, which, in turn, facilitate the intracellular generation of TAGE, all of which may contribute to the pathological changes observed in LSRD. In this review, we discuss the relationships between intracellular TAGE levels and numerous types of cell damage. The novel concept of the “TAGE theory” is expected to open new perspectives for research into LSRD.

Simple Summary Pancreatic cancer has one of the worst prognoses when compared to those of other cancer subtypes. One of the reasons is the resistance of this tumor to the hypovascular environment (an environment with low blood flow and low supply of oxygen and nutrients (especially glucose)). However, the detailed mechanism remains elusive. Recently, it has been reported that heterogeneous ribonuclear protein M (HNRNPM) is a splicing factor associated with malignant tumors. Thus, in this study, we investigated the expression and effects of HNRNPM in pancreatic ductal adenocarcinoma (PDA). We revealed that HNRNPM was highly expressed in pancreatic tissues but expression decreased in PDA tissues. Furthermore, we found that knockdown of HNRNPM protein expression under low-glucose conditions altered glucose metabolism and prolonged cell survival by suppressing glucose consumption. These results suggest that reduced expression of HNRNPM in PDAs may be involved in adaptation to a hypovascular environment, and that therapeutic agents for this target may lead to improved prognosis for pancreatic cancer. Abstract The prognosis of pancreatic cancer is considerably worse than that of other cancers, as early detection of pancreatic cancer is difficult and due to its hypovascular environment, which involves low blood flow and a low supply of oxygen and nutrients. Moreover, pancreatic cancer demonstrates a mechanism that allows it to survive in a hypovascular environment. However, the detailed mechanism remains elusive. Recently, it has been reported that heterogeneous ribonuclear protein M (HNRNPM) is a splicing factor associated with malignant tumors. Thus, in this study, we investigated the expression and effects of HNRNPM in pancreatic ductal adenocarcinoma (PDA). We observed that HNRNPM expression, which is highly expressed in pancreatic tissues, was reduced in PDA tissues. Additionally, knockdown of HNRNPM under low-glucose conditions that mimic a hypovascular environment was shown to alter glucose metabolism and prolong cell survival by suppressing glucose consumption. These results suggest that the decreased expression of HNRNPM in PDA may be involved in its adaptation to a hypovascular environment.

We measure the scale dependence and redshift dependence of 21 cm line emitted from the neutral hydrogen gas at redshift 13 on scales of k>1h/Mpc, but it is roughly constant at lower redshift z, Comment: 10 pages, 6 figures, submitted to MNRAS

Recent progress in submillimetre surveys by single-dish telescopes allows us to further challenge the consistency between cosmological simulations and observations. In particular, we compare our simulations that include dust formation and destruction with the recent SCUBA-2 surveys (`STUDIES') by putting emphases on basic observational properties of dust emission such as dust temperature, size of infrared (IR)-emitting region, IR luminosity function and IRX--$\beta$ relation. After confirming that our models reproduce the local galaxy properties, we examine the STUDIES sample at $z\approx 1-4$, finding that the simulation reproduces the aforementioned quantities except for the $z\gtrsim 2$ IR luminosity function at the massive end ($\sim 10^{13}$ L$_{\odot}$). This means that the current simulation correctly reproduces the overall scaling between the size and luminosity (or star formation rate) of dusty region, but lacks extreme starburst phenomena at $z\gtrsim 2$. We also discuss extinction curves and possible AGN contribution., Comment: 13 pages, 10 figures, published in MNRAS

We have identified ras guanyl releasing protein 2 (rasgrp2) as a blood vessel related gene from Xenopus embryo. In addition, we reported that RASGRP2 is also expressed in human umbilical vein endothelial cells (HUVEC). It is known that RASGRP2 activates Ras-related protein 1 (Rap1). However, the function of RASGRP2 in human vascular endothelium remains unknown. Therefore, we performed functional analysis of RASGRP2 using immortalized HUVEC (TERT HUVEC). We established a stable RASGRP2 overexpressing cell line (TERT HUVEC R) and mock cell line (mock). Furthermore, we compared the activity of Rap1 and the generation of intracellular reactive oxygen species (ROS), which is related to cell death, in both cell lines. Significant increase in Rap1 activity was observed in the TERT HUVEC R compared to the mock. Furthermore, apoptosis by tumor necrosis factor-α (TNF-α) stimulation was significantly more reduced in the TERT HUVEC R than in the mock. In the mock, apoptosis induced by TNF-α stimulation was decreased by pretreatment with diphenyleneiodonium (DPI), which is an inhibitor of NADPH oxidase (NOX). However, in the TERT HUVEC R, apoptosis induced by TNF-α stimulation was not reduced after pretreatment of DPI. Furthermore, there was no reduction in ROS production in the TERT HUVEC R after DPI pretreatment. In addition, the difference in the degree of apoptosis induced by TNF-α stimulation in both cell lines was consistent with the difference in ROS production in the cell lines. From these results, it was suggested that RASGRP2 activates Rap1 and the activated Rap1 suppresses apoptosis via NOX inhibition.

This paper systematically investigates comoving Mpc scale intergalactic medium (IGM) environment around galaxies traced by the Ly$\alpha$ forest. Using our cosmological hydrodynamic simulations, we investigate the IGM-galaxy connection at $z=2$ by two methods: (I) cross-correlation analysis between galaxies and the fluctuation of Ly$\alpha$ forest transmission ($\delta_\text{F}$); and (II) comparing the overdensity of neutral hydrogen (HI) and galaxies. Our simulations reproduce observed cross-correlation functions (CCF) between Ly$\alpha$ forest and Lyman-break galaxies. We further investigate the variation of the CCF using subsamples divided by dark matter halo mass ($M_\text{DH}$), galaxy stellar mass ($M_\star$), and star-formation rate (SFR), and find that the CCF signal becomes stronger with increasing $M_\text{DH}$, $M_\star$, and SFR. The CCFs between galaxies and gas-density fluctuation are also found to have similar trends. Therefore, the variation of the $\delta_\text{F}$-CCF depending on $M_\text{DH}$, $M_\star$, and SFR is due to varying gas density around galaxies. We find that the correlation between galaxies and the IGM HI distribution strongly depends on $M_\text{DH}$ as expected from the linear theory. Our results support the $\Lambda$CDM paradigm, finding a spatial correlation between galaxies and IGM HI, with more massive galaxies being clustered in higher-density regions., Comment: 21 pages, 9 figures, Accepted for publication on ApJ

In order to shed light on how galactic properties depend on the intergalactic medium (IGM) environment traced by the Ly$\alpha$ forest, we observationally investigate the IGM-galaxy connection using the publicly available 3D IGM tomography data (CLAMATO) and several galaxy catalogs in the COSMOS field. We measure the cross-correlation function (CCF) for $570$ galaxies with spec-$z$ measurements and detect a correlation with the IGM up to $50$ $h^{-1}$ comoving Mpc. We show that galaxies with stellar masses of $10^9-10^{10}$ M$_\odot$ are the dominant contributor to the total CCF signal. We also investigate CCFs for several galaxy populations: Ly$\alpha$ emitters (LAEs), H$\alpha$ emitters (HAEs), [OIII] emitters (O3Es), active galactic nuclei (AGNs), and submillimeter galaxies (SMGs), and we detect the highest signal in AGNs and SMGs at large scales ($r\geq5$ $h^{-1}$ Mpc), but in LAEs at small scales ($r, Comment: 27 pages, 16 figures, Accepted for publication on ApJ

We have modeled direct collapse of a primordial gas within dark matter halos in the presence of radiative transfer, in high-resolution zoom-in simulations in a cosmological framework, down to the formation of the photosphere and the central object. Radiative transfer has been implemented in the flux-limited diffusion (FLD) approximation. Adiabatic models were run for comparison. We find that (a) the FLD flow forms an irregular central structure and does not exhibit fragmentation, contrary to adiabatic flow which forms a thick disk, driving a pair of spiral shocks, subject to Kelvin-Helmholtz shear instability forming fragments; (b) the growing central core in the FLD flow quickly reaches ~10 Mo and a highly variable luminosity of 10^{38}-10^{39} erg/s, comparable to the Eddington luminosity. It experiences massive recurrent outflows driven by radiation force and thermal pressure gradients, which mix with the accretion flow and transfer the angular momentum outwards; and (c) the interplay between these processes and a massive accretion, results in photosphere at ~10 AU. We conclude that in the FLD model (1) the central object exhibits dynamically insignificant rotation and slower than adiabatic temperature rise with density; (2) does not experience fragmentation leading to star formation, thus promoting the fast track formation of a supermassive black hole (SMBH) seed; (3) inclusion of radiation force leads to outflows, resulting in the mass accumulation within the central 10^{-3} pc, which is ~100 times larger than characteristic scale of star formation. The inclusion of radiative transfer reveals complex early stages of formation and growth of the central structure in the direct collapse scenario of SMBH seed formation., Comment: 19 pages, 16 figures, MNRAS, accepted for publication

Combining cosmological hydrodynamic simulations and radiative transfer (RT) calculations, we present predictions of multi-wavelength radiative properties of the first galaxies at z ∼ 6–5. We find that intermittent star formation due to supernova (SN) feedback causes the escape fraction of UV photons to fluctuate rapidly, which then produces the observed diversity of SEDs for high-z galaxies. The simulated galaxies make rapid transition between UV-bright and IR-bright phase, and our RT calculations suggest that dust temperatures in the first galaxies are higher than z < 3 galaxies with ∼ 60 K.

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.

Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in interacting dwarf galaxies with halo masses of $\sim 3 \times 10^{7}~M_{\odot}$, which are likely to be the formation sites of early star clusters. Our simulations can resolve both the structure of interstellar medium on small scales of $\lesssim 0.1$ pc and the galactic disk simultaneously. We find that the cold gas clouds form in the post-shock region via thermal instability due to metal-line cooling, when the cooling time is shorter than the galactic dynamical time. The mass function of cold clouds shows almost a power-law initially with an upper limit of thermally unstable scale. We find that some clouds merge into more massive ones with $\gtrsim 10^{4}~M_{\odot}$ within $\sim 2~{\rm Myr}$. Only the massive cold clouds with $\gtrsim 10^{3}~M_{\odot}$ can keep collapsing due to gravitational instability, resulting in the formation of star clusters. In addition, we investigate the dependence of cloud mass function on metallicity and ${\rm H_{2}}$ abundance, and show that the cases with low metallicities ($\lesssim 10^{-2}~Z_{\odot}$) or high ${\rm H_{2}}$ abundance ($\gtrsim 10^{-3}$) cannot form massive cold clouds with $\gtrsim 10^{3}~M_{\odot}$., 11 pages, 11 figures

Recent observations have successfully detected [O III] $88.3\,{\rm \mu m}$ and [C II] $157.6\,{\rm \mu m}$ lines from galaxies in the early Universe with the Atacama Large Millimeter Array (ALMA). Combining cosmological hydrodynamic simulations and radiative transfer calculations, we present relations between the metal line emission and galaxy evolution at $z=6-15$. We find that galaxies during their starburst phases have high [O III] luminosity of $\sim 10^{42}~\rm erg~s^{-1}$. Once supernova feedback quenches star formation, [O III] luminosities rapidly decrease and continue to be zero for $\sim 100\,{\rm Myr}$. The slope of the relation between $\log{(\rm SFR/M_{\odot}~yr^{-1})}$ and $\log{(L_{\rm [O_{III}]}/{\rm L_{\odot}})}$ at $z=6-9$ is 1.03, and 1.43 for $\log{(L_{\rm [C_{II}]}/{\rm L_{\odot}})}$. As gas metallicity increases from sub-solar to solar metallicity by metal enrichment from star formation and feedback, the line luminosity ratio $L_{\rm [O_{III}]} / L_{\rm [C_{II}]}$ decreases from $\sim 10$ to $\sim 1$ because the O/C abundance ratio decreases due to carbon-rich winds from AGB stars and the mass ratio of {\sc H\,ii} to {\sc H\,i} regions decreases due to rapid recombination. Therefore, we suggest that the combination of [O III] and [C II] lines is a good probe to investigate the relative distribution of ionized and neutral gas in high-$z$ galaxies. In addition, we show that deep [C II] observations with a sensitivity of $\sim 10^{-2}~{\rm mJy~arcsec^{-2}}$ can probe the extended neutral gas disks of high-$z$ galaxies., Comment: 19 pages, 19 figures, 1 table. Accepted for publication in MNRAS

This paper investigates the hierarchy of baryon physics assembly bias relations obtained from state-of-the-art hydrodynamic simulations with respect to the underlying cosmic web spanned by the dark matter field. Using the Bias Assignment Method (BAM) we find that non-local bias plays a central role. We classify the cosmic web based on the invariants of the curvature tensor defined not only by the gravitational potential, but especially by the over-density, as small scale clustering becomes important in this context. First, the gas density bias relation can be directly mapped onto the dark matter density field to high precision exploiting the strong correlation between them. In a second step, the neutral hydrogen is mapped based on the dark matter and the gas density fields. Finally, the temperature is mapped based on the previous quantities. This permits us to statistically reconstruct the baryon properties within the same simulated volume finding percent-precision in the two-point statistics and compatible results in the three-point statistics, in general within 1-$\sigma$, with respect to the reference simulation (with 5 to 6 orders of magnitude less computing time). This paves the path to establish the best set-up for the construction of mocks probing the intergalactic medium for the generation of such key ingredients in the statistical analysis of large forthcoming missions such as DESI, Euclid, J-PAS and WEAVE., Comment: Accepted for publication by ApJ

We present results from a new cosmological hydrodynamics simulation campaign of protocluster (PC) regions, FOREVER22: FORmation and EVolution of galaxies in Extremely-overdense Regions motivated by SSA22. The simulations cover a wide range of cosmological scales using three different zoom set-ups in a parent volume of $(714.2~\rm cMpc)^{3}$: PCR (Proto-Cluster Region; $V= (28.6~{\rm cMpc})^{3} $, SPH particle mass, $m_{\rm{SPH}} = 4.1 \times 10^{6}~\rm M_{\odot}$ and final redshift, $z_{\rm end}=2.0$), BCG (Brightest proto-Cluster Galaxy; $V \sim (10~{\rm cMpc})^{3} $, $m_{\rm SPH} = 5.0\times10^{5}~\rm M_{\odot}$ and $z_{\rm end}=4.0$ ), and First ( $V \sim (3~{\rm cMpc})^{3} $, $m_{\rm SPH} = 7.9 \times 10^{3}~\rm M_{\odot}$ and $z_{\rm end}=9.5$) runs, that allow to focus on different aspects of galaxy formation. In the PCR runs, we follow 10 PCs, each harbouring 1 - 4 SMBHs with $M_{\rm BH} \ge 10^{9}~\rm M_{\odot}$. One of the PC cores shows a spatially close arrangement of seven starburst galaxies with ${\rm SFR} \gtrsim 100~\rm M_{\odot}~yr^{-1}$ each, that are dust-obscured and would appear as submillimeter galaxies with flux $\gtrsim 1~$ mJy at $1.1~ \rm mm$ in observations. The BCG runs show that the total SFRs of haloes hosting BCGs are affected by AGN feedback, but exceed $1000~\rm M_{\odot}~yr^{-1}$ at $z \lesssim 6$. The First runs resolve mini-haloes hosting population (Pop) III stars and we show that, in PC regions, the dominant stellar population changes from Pop III to Pop II at $z \gtrsim 20$, and the first galaxies with ${\rm SFR} \gtrsim 18~\rm M_{\odot}~yr^{-1}$ form at $z \sim 10$. These can be prime targets for future observations with the James Webb Space Telescope. Our simulations successfully reproduce the global star formation activities in observed PCs and suggest that PCs can kickstart cosmic reionization., Comment: 24 pages, 19 figures, accepted for publication in MNRAS

Apoptosis of endothelial cells is a very important event in various diseases and angiogenesis. We recently reported that ras guanyl nucleotide releasing protein 2 (RasGRP2), which is a guanine nucleotide exchange factor, was expressed in the human umbilical vein endothelial cells (HUVECs) and that Rap1 activation by its overexpression inhibited apoptosis by suppressing tumor necrosis factor-α induced-reactive oxygen species (ROS) production. However, other signaling pathways and roles of RasGRP2 not mediated via Rap1 are not well understood. Therefore, we compared the Mock (M) and the RasGRP2-stable overexpression (R) immortalized HUVECs using BAM7 and anisomycin, which are apoptosis inducers. BAM7 and anisomycin induced apoptosis without causing ROS production, and such apoptosis was significantly increased in M cells, but not in R cells. RasGRP2 suppressed BAM7- and anisomycin-induced apoptosis, but not via the Rap1 pathway as observed using Rap1 knockdown. Furthermore, RasGRP2 activated not only Rap1 but also R-Ras, and suppressed apoptosis by activating R-Ras-phosphoinositide 3-kinase (PI3K)-Akt signaling pathway. The phosphorylation of Akt by RasGRP2 inhibited Bax translocation by promoting translocation of hexokinase-2 (HK-2) from cytoplasm to mitochondria. Taken together, it was suggested that RasGRP2 suppresses the Bax activation-induced apoptosis by promoting HK-2 translocation to mitochondria via R-Ras-PI3K-Akt signaling pathway.

Observations of high-redshift quasars imply the presence of supermassive black holes already at z~ 7.5. An appealing and promising pathway to their formation is the direct collapse scenario of a primordial gas in atomic-cooling haloes at z ~ 10 - 20, when the $\rm H_2$ formation is inhibited by a strong background radiation field, whose intensity exceeds a critical value, $J_{\rm crit}$. To estimate $J_{\rm crit}$, typically, studies have assumed idealized spectra, with a fixed ratio of $\rm H_{2}$ photo-dissociation rate $k_{\rm H_2}$ to the $\rm H^-$ photo-detachment rate $k_{\rm H^-}$. This assumption, however, could be too narrow in scope as the nature of the background radiation field is not known precisely. In this work we argue that the critical condition for suppressing the $\rm H_2$ cooling in the collapsing gas could be described in a more general way by a combination of $k_{\rm H_2}$ and $k_{\rm H^-}$ parameters. By performing a series of cosmological zoom-in simulations with an encompassing set of $k_{\rm H_2}$ and $k_{\rm H^-}$, we examine the gas flow by following evolution of basic parameters of the accretion flow. We test under what conditions the gas evolution is dominated by $\rm H_{2}$ and/or atomic cooling. We confirm the existence of a critical curve in the $k_{\rm H_2}-k_{\rm H^-}$ plane, and provide an analytical fit to it. This curve depends on the conditions in the direct collapse, and reveals domains where the atomic cooling dominates over the molecular cooling. Furthermore, we have considered the effect of $\rm H_{2}$ self-shielding on the critical curve, by adopting three methods for the effective column density approximation in $\rm H_{2}$. We find that the estimate of the characteristic length-scale for shielding can be improved by using $\lambda_{\rm Jeans25}$, which is 0.25 times that of the local Jeans length., Comment: 10 pages, 5 figures, accepted for publication in MNRAS