Program

Opening Remark (10 mins)

6:05 pm – 6:15 pm (KST)
Juhan Kim (KIAS, Korea)

Short Talks (12+3 mins)

6:15 pm – 6:30 pm (KST)
Jaehyun Lee (KIAS, Korea): - Title : Data and catalogues of Horizon Run 5; - Abstract: Horizon Run 5 produces snapshots, lightcone space data, and the data set of 5 dense regions with time steps finer than that of the snapshots. We generate galaxy and halo catalogues from the snapshots and lightcone space data. For the catalogues, we first carry out structure finding using PSB-based Galaxy Finder (PGalF). PGalF first finds Friends-of-Friends (FoF) haloes from all the matter components of HR5 and identifies self-bound objects in the FoF haloes. We assume that a self-bound object is a galaxy when it contains stellar components. From the outputs of the structure finding, we compute reduced properties of haloes and galaxies. We also construct the merger trees of the self-bound objects based on the most-bound particle scheme. In addition to this scheme, we use the unique IDs of stellar particles for better constructing galaxy merger trees. We now provide halo and galaxy catalogues in ascii and binary formats, merger trees, structure finding outputs which contain the full information of particles and gas cells in each structure, and raw simulation snapshots.
6:30 pm – 6:45 pm (KST) / 11:30 am - 11:45 am CEST
Céline Gouin (Institut d'Astrophysique Spatiale, France): - Title: Investigating the connection of galaxy clusters to the cosmic web; - Abstract: Galaxy clusters are connected to cosmic filaments that funnel accreting material. The large-scale environment of galaxy clusters is therefore ideal to investigate the growth of massive structures and the influence of the cosmic web on clusters. By using IllustrisTNG simulation, I will show the influence of cosmic web on cluster structural and dynamical properties. We will see that the connection of cluster to the cosmic web is correlated to the cluster dynamical state. It appears to be the sign of different mass assembly histories of clusters. I will present some possible future projects, using Horizon Run 5 simulations, that I propose to investigate the growth and building up of clusters by the accretion along filaments.
6:45 pm –7:00 pm (KST)
Seong-Kook Lee (Seoul National University, Korea): - Title: Star-formation properties of high-redshift galaxy clusters in HR5; - Abstract: Unlike local, where galaxy properties show a clear environmental-dependent bimodality, galaxy clusters at high redshift (z~1) show a wide range in their star-formation status. I will report the on-going analysis on this using mock galaxy cluster samples from HR5 at redshift z~0.9.
7:00 pm –7:15 pm (KST)/ 11 am –11:15 am (BST)
Emily Shelton (University of Hull, UK): - Title: Large Scale Structure Quantified Via Percolation Theory; - Abstract: TBA
7:15 pm –7:30 pm (KST)
Hyunsung Jun (KIAS, Korea): - Title: Galaxy Environment of Massive Quasars: Constraints From Horizon Run 5 Simulations; - Abstract: We aim to measure the Mpc-scale galaxy environment of supermassive black holes in the intermediate age Universe, using the Horizon Run 5 cosmological hydro-dynamical simulation. Quasars are known to trace Mpc-scale galaxy overdensities, but their luminosity is powered by fueling mechanisms that may not always favor dense environments, along with the luminosity itself being poorly correlated with black hole mass. We use the black hole mass as an alternative indicator of the halo mass or galaxy number density. We will study the behavior of the quantities at 1 < z < 2, and link the relations to predict observations.
7:30 pm –7:45 pm (KST)
Ankit Singh (KIAS, Korea): - Title: Study of effects of local environment on AGN; - Abstract: Galaxies are the building blocks of the Universe. They can be classified based on their star-forming rates into active and passive. Most massive galaxies host a supermassive black hole at the center. The central black hole gets activated by events of accreting mass from surrounding and achieves a state known as active galactic nuclei (AGN). Various observations have shown that AGNs play a crucial role in shaping the properties of the galaxies. Several observational works studying how the environment affects the AGN properties have reported an increase, decrease and no change in AGN activity. On the other hand, the effect of the environment on AGN using hydrodynamical simulations is relatively less studied. In this talk, I will show my recent progress on using the Horizon Run5 cosmological simulation to study the properties of AGNs in different environments.
7:45 pm – 8:00 pm (KST)
Break
8:00 pm –8:15 pm (KST)
Yonghwi Kim (KIAS, Korea): - Title: HR5 spin-off simulations : LAE-HR and CUBE-HR; - Abstract: Brief introduction to new simulation projects for studying the formation of Lyman-alpha emitters and large-scale structures
8:15 pm – 8:30pm (KST)/ 1:15 pm - 1:30 pm (CEST)
Clotilde Laigle (Institut d'Astrophysique de Paris, France) & Hyunmi Song (Yonsei University, Korea): - Title: Building mocks from HR5: 1. Evolution of the UV luminosity functions & 2. Properties of the ELG population; - Abstract: We will discuss the progress of two on-going projects related to the preparation of SEDs for HR5 galaxies and the analysis of their photometry in comparison with observations.1) The first project consists in measuring the evolution of UV luminosity functions (UVLF) throughout cosmic time and carrying out a detailed comparison to observations. Amongst other effects, we quantify the impact of the dust attenuation recipes on the shape of the UVLF. Incidentally, this comparison allows us to determine the dust model which provides the best agreement with observations, and which will be used in project 2. 2) The second project consists in mimicking, with HR5, the selection of emission-line galaxies (ELG) at 0.5 < z < 1.5 based on their broad-band photometry (in the configuration of current and upcoming surveys: e.g. eBOSS and DESI) with different dust attenuation models. We will then investigate the star-formation histories, galaxy-halo connection, environment and spatial distribution of these galaxies. We discuss to which extent they are a good representation of the entire star-forming galaxy population and, as a consequence, how these selections might bias either cosmological measurements and or the study of the evolution of star-forming galaxies.
8:30 pm – 8:45 pm (KST)
Ankit Singh (KIAS, Korea): - Title: Impact of AGN emission on estimated star formation rate using infrared (IR) luminosity of galaxies in Horizon Run-5 simulation; - Abstract: Measuring the star formation rate (SFR) of galaxies in observation is a challenging task. For dusty sources and galaxies with high star formation rates, the tracer of choice is far-infrared luminosity for the estimation. If the bolometric emission is dominated by old stars or active galactic nuclei (AGN), this estimation tends to give wrong results. Detecting the latter part is very hard as emission from both AGN and stars gets reprocessed by the dust. We will use Horizon Run-5 (HR5) simulation to get Spectral Energy Distribution (SED) of galaxies using dust radiative transfer simulation. We will study the influence of AGNs on SFR estimates using infra-red emissions. The study will further explore the effects of the galaxies' star formation history on the estimated SFR. In this talk I will update my recent progress on this project.
8:45pm – 9:00pm (KST)
Break
9:00 pm – 9:15 pm (KST)/ 8:00 am – 8:15 am (EDT)
Hyo Sun Park (Bryn Mawr College, USA): - Title: PTA and Search for Gravitational Waves from Supermassive Black Hole Binaries; - Abstract: Pulsars are fast-spinning neutron stars that emit beams of radio waves, which are observed as pulses to distant observers. The times of arrival (TOAs) of pulses from millisecond pulsars are extremely stable such that any perturbation in spacetime, such as gravitational waves (GWs), can cause the TOAs to deviate from the expected TOAs. By monitoring the correlation of TOAs from a set of pulsars, Pulsar Timing Arrays (PTAs) can detect nanohertz GWs, which are dominantly emitted by supermassive black hole binaries (SMBHBs). The main targets of PTAs include continuous waves emitted by individual bright SMBHBs and a stochastic gravitational wave background (GWB), formed collectively by an ensemble of distant SMBHBs. In this talk, we will introduce GW detection using PTAs and show some highlights of recent progress made by the NANOGrav collaboration. We present our proposal to utilize SMBHBs generated by HR5 to create a simulated pulsar data set that we can use to test GW detection algorithms.
9:15 pm – 9:30 pm (KST)
Chunglee Kim (Ewha Womans University, Korea): - Title: HR5 black holes and PTA; - Abstract: Merging of two supermassive black holes would generate gravitational waves that can be detected by the Pulsar Timing Array (PTA) in the nHz band. In order to assess the plausibility of GW detection with PTA and to develop the data analysis scheme, it is important to understand the underlying properties of black holes and black hole binaries. In this work, we present mass and redshift distributions of black hole mergers using the Horizon Run 5 data and discuss their implications for GW detection. We find a general conjecture about the black hole merger tree is true with the Horizon Run 5. That is, relatively lighter black holes merge at higher redshifts. Binary mergers do contribute to the formation of more massive black holes toward low redshifts. Physical quantities such as mass, distance (obtained from redshift), and/or separation obtained from the Horizon Run 5 would be key ingredients to generate a more realistic PTA source data set. As a follow-up project, we plan to use the black hole properties extracted from the Horizon Run 5 data in order to generate simulated GW signals to be injected into actual PTA data analysis pipelines.

HR5 Sciences (20+5 mins)

9:30 pm – 10:00 pm (KST)
Jaehong Park (KIAS, Korea): - Title: Modelling Lyman-alpha emitters in HR5; - Abstract: Lyman-alpha emitters (LAEs) are known to be young and active star-forming galaxies. Since LAEs are less dusty, these are a good tracer of the underlying matter distribution. This project aims to model LAEs to understand the formation and evolution of LAEs, and their large-scale structure. The predicted LAEs from HR5 will be compared with LAEs observed from One-hundred-square-degree DECam Imaging in Narrow band (ODIN) survey at z = 2.4, 3.1, and 4.5, which is conducting in the largest survey area of total ~91 deg^2. In this talk, I will introduce an empirical approach to model LAEs and present recent progress.
10:00 pm – 10:30 pm (KST)
Changbom Park (KIAS, Korea): - Title: Morphology of the First Galaxies in the HR5 Simulation; - Abstract: TBA

Summary of meeting and future goals (10 mins)

10:30 pm – 10:45 pm (KST)
Changbom Park (KIAS, Korea)