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Monday, Oct. 29th
9:50-11:00 Session 1
Author : John Wise
Title : First Galaxies
Abstract : I review recent results from early dwarf galaxy simulations that particularly focus on the transition
from metal-free Population III stars to the formation of the ﬁrst galaxies before redshift 7. We have investigated thevariations in galaxy properties when changing the Pop III characteristic mass, critical metallicity, UV backgrounds,
metal cooling, and feedback from radiation pressure. One constant result from all the simulations is a metallicity
ﬂoor between [Z/H] = -3 to -4. We show that momentum transfer from ionizing radiation plays an important role inproviding turbulent support and mixing metals, preventing the overproduction of stars and metals. This results in astellar population with a tight metallicity distribution function centered at [Z/H] = -2, agreeing with the observed
luminosity-metallicity relation in dwarf galaxies.
11:20-12:35 Session 2
Author : Juntai Shen
Title : Formation of the Milky Way
Abstract : TBA
Author : Greg Stinson
Title : Making Galaxies in a Cosmological Context (MaGICC)
Abstract: I will present results from the MaGICC project in which we used fully cosmological; smoothed particle
hydrodynamics simulations of disk galaxy formation. This large computational project combines zoomed-in cosmological simulations of single galaxies at very high resolution with simulations of a large portion of the universe ( 100Mpc)3 at moderate resolution to gain statistical information on the whole galaxy population. We have used a new
implementation of the SPH scheme able to remove numerical artifacts due to inability of SPH to capture gas phasemixing. This project requires high performance computing and is generating one of the largest data-base for discgalaxy simulations. I will discuss the current success of MaGICC galaxies in reproducing several structural propertiesof observed galaxies.
14:00-15:30 Session 3
Author : Kohji Yoshikawa
Title : Vlasov-Poisson simulations of collisionless self-gravitating systems
Abstract : We present an alternative approach for simulating astrophysical collisionless self-gravitating systems;
which directly integrates the collisionless.
Author : Qi Guo
Title : The limits of subhalo abundance matching
Abstract : We scale the Millennium and Millennium-II simulations of structure growth in a LCDM universe from thecosmological parameters with which they were carried out (based on ﬁrst-year results from the Wilkinson Microwave
Anisotropy Probe; WMAP1) to parameters consistent with the seven-year WMAP data (WMAP7). We implement
semi-analytic galaxy formation modelling on both simulations in both cosmologies to investigate how the formation;
evolution and clustering of galaxies are predicted to vary with cosmological parameters.
Author : Go Ogiya
Title : Landau resonance and the core-cusp problem in cold dark matter halos
Abstract : The coreusp problem still remains as one of the unsolved discrepancies between observations and theories
predicted by the standard paradigm of cold dark matter (CDM) cosmology. Cosmological N-body simulations havealways predicted a steep power-law mass-density proﬁle at the center of CDM halos. However; recent observations ofless-massive galaxies have revealed that the density proﬁle of the dark matter (DM) halo is nearly constant aroundthe center. The burst of star formation at the galactic center induces the large-scale outﬂow from the galactic center;and then the star formation terminates. Subsequently; gas component falls back toward the galactic center; if it loses
a large amount of energy by the radiative cooling; and then a starburst arises again. This cycle of expansion andcontraction of the interstellar gas could lead to the recurring change in the gravitational potential around the centerof galaxies and have an impact on the density proﬁle of the DM halos. To test this hypothesis; we investigate the2dynamical response of DM halos with a central cusp to recurring change of the baryon potential by using collisionlessN-body simulations. The results show that the cycle of expansion and contraction of the interstellar gas is an eﬀective
mechanism for ﬂattening the central cusp. The frequency of the star formation is one of the important factors indetermining the dynamical response of DM halos. Furthermore; we compare these results with an analytical modelof the resonance between the DM particles and the density waves of the interstellar gas which induce the recurringchange of the gravitational potential. This analysis indicates that the resonance plays a decisive role for the cusp tocore transition of the CDM halos; and can resolve the core-cusp problem.
Author : Taira Oogi
Title : Size evolution of early-type galaxies through dry mergers
Abstract : Recent observations show evidence that high-z (z ∼ 2 − 3) early-type galaxies (ETGs) are more compact
than those with comparable mass at z ∼ 0. Such a size evolution is most likely explained by the ‘Dry Merger Sceanario’.
However; previous studies based on this scenario are not able to consistantly explain both the properties of the high-z
compact massive ETGs and the local ETGs. We investigate the eﬀect of multiple sequential dry minor mergers on thesize evolution of the compact massive ETGs. From an analysis of the Millennium Simulation Database; we show thatsuch minor (stellar mass ratio M2 /M1 < 1/4) mergers are extremely common during hierarchical structure formation.
We perform N-body simulations of sequential minor mergers with parabolic and head-on orbits; including a dark
matter component and a stellar component. Typical mass ratios of the minor mergers are 1/20 < M2 /M1 < 1/10. We
show that sequential minor mergers of compact satellite galaxies are the most eﬃcient at promoting size growth anddecreasing the velocity dispersion of the compact massive ETGs in our simulations. The change of stellar size anddensity of the merger remnants is consistent with recent observations. Furthermore; we construct the merger histories
of candidates for the high-z compact massive ETGs using the Millennium Simulation Database; and estimate the size
growth of the galaxies by the dry minor merger scenario. We can reproduce the mean size growth factor betweenz = 2 and z = 0; assuming the most eﬃcient size growth obtained during sequential minor mergers in our simulations.
However; we note that our numerical result is only valid for merger histories with typical mass ratios between 1/20
and 1/10 with parabolic and head-on orbits; and that our most eﬃcient size growth eﬃciency is likely to an upper
limit.
Author : Hesti R.T. Wulandari
Title : Impact of Orbital Eccentricity on the Capture of WIMP Dark Matter by Stars in the Galactic Center
Abstract : In the regions where high density of WIMP (Weakly Interacting Massive Particle) dark matter is
expected; capture and annihilation of WIMPs have been suggested to inﬂuence the structure and evolution of stars(e.g. : Moskalenko & Wai (2007); Bertone & Fairbairn (2008) and Scott et al. (2009)). The capture rate depends
on several parameters such as stellar mass; WIMP ambient density; WIMP mass; WIMP-nucleon cross section;
metalicity and WIMP velocity distribution. In this presentation we will report results of study of the inﬂuence oforbital eccentricity on the capture rate of WIMPs by stars in the Galactic center. Especially; we study the inﬂuence
on S-stars; young stars which are located very close to the Supermassive Black Hole at the Galactic center. The
orbital parameters of 28 of the stars have been measured by Gillessen et al. (2009). We follow the orbital movementsof these stars by using Mercury code (Chambers 1999); in which we introduce general relativity correction in theequations of motions. To simulate capture and annihilation of WIMPs by stars and follow their evolutions; we employ
DarkStar code (Scott et al. 2009). Constraints from several current dark matter experiments on the value of WIMP
mass and cross sections are used.
15:50-17:00 Session 4
Author : Hyesung Kang
Title : Particle Acceleration at Astrophysical Shocks
Abstract : TBA
Author : Franco Vazza
Title : The injection and evolution of cosmic ray hadrons in cosmological simulations
Abstract : The presence of relativistic protons within large scale structure is predicted by basic models of diﬀusive
shock acceleration in cosmological shocks; and as a byproduct of active galactic nuclei and supernovae. I will review the
recent implementations of cosmic rays evolution in our cosmological simulations employing adaptive mesh reﬁnement;
and their application to simulate observables in galaxy clusters. From the close comparison with available upper-limitsof gamma observation (from the FERMI satellite) and radio data; important constraints on the eﬃciency of particle
acceleration in the largest scale of the Universe can be derived from our simulations.

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Tuesday, Oct. 30th
9:30-10:45 Session 5
Author : Tom Abel
Title : Following Dark Matter into Phase Space
Abstract : This talk gives some pedagogical remarks of how to understand the evolution of dark matter in phasespace and then gives a more technical discussion of the use of N-body techniques in numerical cosmology. In fact,
tessellating sheets in phase space allows one to derive accurate density estimates of and study details of the ﬁne grain
phase space distribution of dark matter in numerical simulations. Most surprisingly this information has always been
included in N-body simulations but had previously been thought to be inaccessible. The insights gained from this new
approach gives a clear path forward to devise simulation techniques that solve for the dark matter as a continuous ﬂuid
rather than Monte-Carlo sample it using the N-body technique. I show ﬁrst results from new numerical techniquesthat can overcome some of the limitations of the current standard technique and discuss their own shortcomings. The
approaches discussed here also generalize to the study of collisionless plasmas.
Author : Marcel Zemp
Title : Molecular Hydrogen based Star Formation
Abstract : I present results from cosmological structure formation simulations of galaxies at redshifts z ¿ 2. Thesesimulations have an improved modeling of the interstellar medium and star formation. The simulations follow theformation and dissociation of molecular hydrogen and include star formation only in cold molecular gas. The molecular
gas is more concentrated toward the center of galaxies than the atomic gas; and as a consequence; the resulting stellar
distribution is very compact. I present results on the detailed structure of diﬀerent matter components in the highredshift galaxies that form in these simulations.
11:05-12:35 Session 6
Author : Miguel-Angel Aloy
Title : ”GRB Jets”
Abstract : TBA
Author : Jin Matsumoto
Title : Eﬀect of Interacting Rarefaction Waves on Relativistically Hot Jets
Abstract : The eﬀect of rarefaction acceleration on dynamics and structure of relativistically hot jets is studied
through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excitedat the interface between a cylindrical jet and the surrounding medium. From simpliﬁed one-dimensional models withradial jet structure; we ﬁnd that a decrease in the relativistic pressure due to the interacting rarefaction waves in
the central zone of the jet yields more a powerful boost of the bulk jet transiently than that expected from single
rarefaction acceleration. This leads to a cyclic in-situ energy conversion between thermal and bulk kinetic energies
which induces radial oscillating motion of the jet. It is conﬁrmed from extended multi-dimensional simulations that
this radial oscillating motion in one-dimensional system triggers Rayliegh-Taylor and Richtmyer-Meshkov instabilities
in the relativistic jet.
Author : Akira Mizuta
Title : Jet Opening angle of gamma-ray burst outﬂows
Abstract : Gamma-Ray Bursts (GRBs) are the most energetic explosions in the Universe. The outﬂow is considered
as ultra relativistic jet with small viewing angle (∼ 0.1 rad.). It is important problem what physics determines thejet opening angle. Especially for long-GRBs the jet is not able to freely expand due to the cocoon conﬁnement before
jet break from the progenitor surface. We have done two dimensional relativistic hydrodynamic simulations to study
the evolution of the jet opening angle. We have conﬁrmed that the opening angle is smaller than the theoretically−1prediction; i.e. θj ∼ Γ−1
0 ; where Γ0 is initial jet Lorentz factor. The jet opening angle is rouhly 0.2Γ0 .
14:00-15:30 Session 7
Author : Yuichiro Sekiguchi
Title : Merger of Binary Neutron Stars
Abstract : In this talk; I will give a review on recent studies of numerical-relativity simulations of merger of binary

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neutron stars. In particular; I will focus on recent studies on constraining the equation of state of neutron star matter
using gravitational waves from the merger; and; possible electromagnetic counterparts of the merger events.
Author : Kenta Kiuchi
Title : General relativistic simulation of black hole - neutron star binary mergers
Abstract : I will give a talk about numerical relativity simulations of black hole - neutron star binary merger
including a ﬁnite temperature equation of state and neutrino cooling.
Author : Ke-Jung Chen
Title : 3D Simulations of Thermonuclear Supernovae from the Most Massive Stars
Abstract : We present the results from our 3D simulations of thermonuclear supernovae from the stars with initial
masses above 80 solar mass (Msun) using an AMR radiation-hydrodynamics code; CASTRO. Recent observations
support the existence of very massive stars with initial masses over 100 Msun. After central helium burning; the coreof such massive stars encounters electron/positron creation instabilities leading the stars to catastrophic collapse. The
ﬁnal fates of these stars are determined by the explosive burning during collapse. For the stars with initial masses
between 80 and 140 Msun; they die as pulsational pair-instability supernovae (PPSNe). The collisions between
shells of matter ejected by PPSNe might produce the superluminous SNe. For the stars with initial masses between
140 and 250 Msun; they die as pair-instability supernovae (PSNe); completely unbinding the stars and leaving nocompact remnant. Our simulations model the explosive burning and resolve the ﬂuid instabilities that occur during
the explosion. We will discuss how the resulting mixing aﬀects the explosion; nucleosynthesis; and observationalsignature of these supernovae.
Author : Yudai Suwa
Title : Numerical Simulation of Core-Collapse Supernovae
Abstract : I will present about our recent result of the multi-dimensional simulation for the core-collapse supernova
explosion. We have performed 2D and 3D simulation including neutrino radiative transfer. The systematics of themodeling (e.g.; dimensionality; the equation of state; progenitor; etc.) will be discussed.
Author : Sergey Moiseenko
Title : Implicit Lagrangian method on variable triangular grid for magnetorotational supernova simulations
Abstract : We present specially developed implicit completely conservative operator-diﬀerence scheme on triangular
Lagrangian grid of variable structure. The reconstruction of the grid allows dynamically adapt it. The Lagrangian
nature of the method allows to conserve angular moentum.The method was applied for the simulations of magnetorotational (MR) supernova explosion mechanism. We show that MR supernova gives enough energy for the explanation
core-collapse supernova event. MR instability in core-collapse supernova.
15:50-17:00 Session 8
Author : Michele Montgomery
Title : Missing Physics in Simulations of Accretion Disks
Abstract : Modulations in light curves and signals in associated Fourier transforms from compact binary systems
inform us that disks precess in the prograde direction; in the retrograde direction; and sometimes simultaneously inboth directions. Emission lines from these same systems show outlying data points around phase ; 0.5 that is often
ignored in ﬁnding the orbital period and stellar mass of the system. Using 3D Smoothed Particle Hydrodynamics(SPH); we can reproduce all the observables and thus explain the outlying data points in the RV curves. By doingso; we conﬁrm proposed models of disk tilt from decades ago. As shown in two Letters to the Astrophysical Journal
in 2012; the source to disk tilt is not due to radiation from a central source; magnetic ﬁelds; or gravity; thereby
supporting our model of lift as the source to disk tilt. Disk tilt is necessary to explain twisted disks around planetsin addition to reproducing observables from compact binary systems; suggesting disk tilt is a common phenomena
in many diﬀerent accretion systems and thus a test to SPH codes on ﬂuid ﬂow in accretion disk systems. If time
permits; we will discuss disk tilt results using 3D HD; MHD; and a radiative transfer grid code.
Author : Motoyuki Saijo
Title : Nonlinear eﬀect of r-mode instability in uniformly rotating stars
Abstract : We investigate the r-mode instability of uniformly rotating stars by means of three dimensional hydrodynamical simulations in Newtonian gravity with radiation reaction. We propose a nonlinear anelastic approximationin the rotating reference frame; which kills the propagation of sound speed; in order to evolve the system beyond theacoustic timescale. We succeed in evolving uniformly rotating stars up to at least around several hundred rotation

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period with our new scheme; which is at least 10 times longer than the previous standard hydrodynamical simulations.
In order to verify our developed code; we impose the harmonic index of l=m=2 perturbation of an incompressible
unstable r-mode eigenfunction to the equilibrium velocity; and ﬁnd that the characteristic frequency of the unstabler-mode is excited throughout the evolution. We discuss the features of nonlinear r-mode instability with our newly
developed code; such as saturation amplitude and the breaking wave eﬀect of its instability.

Wednesday, Oct. 31st
9:30-11:00 Session 9
Author : Xian Chen
Title : Tidal Stellar Disruption by Binary Supermassive Black Holes
Abstract : Formation of binary supermassive black holes in galaxy centers is predicted by the hierarchical galaxy
formation model. The coalescence of these binaries produces the loudest gravitational wave radiation detectable by
LISA and PTA. Motivated by the recent success in detecting the electromagnetic ﬂares from tidal disruptions of stellar
objects by single supermassive black holes, we investigate the eﬀects of binary black holes on the process of tidal stellar
disruption, and their observational signatures. Using numerical scattering experiments, we calculated the stellar orbits
around binary black holes, and found that the stellar-disruption rate diﬀers from those in single black hole systems
by orders magnitude. Based on such diﬀerence, we discuss the prospect of utilizing synoptic sky surveys to constrain
the cosmic merger history of supermassive black holes. We also propose observational strategies to discover systems
containing supermassive black hole binaries, especial for those in the regime of strong gravitational-wave radiation.
Author : Ken Ohsuga
Title : Radiation Magnetohydrodynamics of Black Hole Accretion Flows and Outﬂows
Abstract : By performing radiation magnetohydrodynamic (radiation-MHD) simulations, we succeeded in reproducing three distinct accretion modes, which are multi-dimensional version of slim disk, standard disk, and RIAF.
In the case of moderate and low mass accretion rates (standard disk and RIAF), we ﬁnd that the magnetic pressure
force drives the outﬂows. The radiatively driven disk winds and jets are launched from the super-Eddington disks(slim disk). The jets are magnetically collimated and disk winds fragment into many clouds via radiation-pressure
instability. Our model would resolve the recent X-ray observations of ULXs and AGNs.
Author : Kinsuk Giri
Title : Numerical simulations of a Two Component Advective Flow: Is The Flow Stable?
Abstract : Numerical simulations of a Two Component Advective Flow : Is The Flow Stable ? Two component
advective ﬂows are the most physical accretion disks which arise from theoretical consideration. Here high viscosity
matter settles as the Keplerian disk on the equatorial plane; while low viscosity matter having lower angular momentumis accreted above and below this plane. Since viscosity is the determining factor; we investigate the eﬀects of viscousstresses on accretion ﬂows around a non-rotating black hole by time dependent hydrodynamical calculations; in great
detail. As a consequence of angular momentum transfer by viscosity in a two-dimensional; rotating; axi-symmetricaccretion ﬂow; the angular momentum distribution is modiﬁed. We show that the centrifugal pressure supported
shocks became weaker with the inclusion of viscosity. We also ﬁnd that as the viscosity is increased; the amountof out ﬂowing matter in the wind is decreased to less than a percentage of the inﬂow matter. Since the post-shock
region acts as a reservoir of hot electrons or the so-called Compton cloud; the size of which changes with viscosity; thespectral properties are expected to depend on viscosity very strongly: the harder states are dominated by low-angularmomentum and the low viscosity ﬂow with a signiﬁcant outﬂows while the softer states are dominated by the highviscosity Keplerian ﬂow having very little outﬂows. We include cooling eﬀects and found that a Keplerian disk is
produced on the equatorial plane and the ﬂow above and below remains sub-Keplerian. This gives a complete picture
to date; of the formation of a Two component advective ﬂow around a black hole.
Author : Tomohisa Kawashima
Title : Hot Spine and Compton-Cooled Sheath Structure of Radiation MHD Jet: Observational Feature of SuperEddington Black Hole Accretion Flow with Outﬂow
Abstract : Recently; the structure of jets launched from super-Eddington accretion ﬂows is studied by performing
radiation MHD (hereafter Rad-MHD) simulations (Ohsuga et al. 2009; 2011: Takeuchi 2010). The previous studies;
however; did not take into account the eﬀects of Compton cooling; while radiation hydrodynamic simulations including
Compton cooling/heating showed that the temperature of the jet is signiﬁcantly decreased by Compton cooling(Kawashima et al. 2009). The detailed structure of outﬂows is important because the Compton cooled outﬂows

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signiﬁcantly modify the photon spectra of super-Eddington accretion ﬂows (Kawashima et al. 2012). We carriedout; therefore; axisymmetric 2D Rad-MHD simulations of the super-Eddington black hole accretion ﬂows; taking
into account the eﬀects of Compton cooling/heating. We found a hot spine and Compton-cooled sheath structure in
the radiation pressure driven jets. The plasma temperature of the sheath jets decreases to ∼ 107 K via the Compton
cooling; while the simulations without Compton cooling show hot (∼ 109 K) sheath jets. We propose that the Compton
downscattering in the sheath jet can form the photon spectral rollover at ∼ 5 keV observed in ultraluminous X-ray
sources.
11:20-12:35 Session 10
Author : Yohei Miki
Title : Galaxy Merger and Hungry Black Hole: Suppression of Black Hole Activity due to Galaxy Merger
Abstract : Supermassive Black Holes (SMBHs) exist in the central region of galaxies universally; and have been
considered to become luminous as Active Galactic Nuclei (AGN) by releasing gravitational energy of accreting gas;
if a suﬃcient amount of gas accreted to the central SMBH. Galaxy collisions have been so far considered enhancing
the AGN activity; by triggering mass fueling to the central SMBH due to angular momentum transfer (Sanders etal. 1988 etc.). However; galaxy collisions may be able to suppress the AGN activity: if mass reservoir of the central
SMBH is swept away by galaxy collisions; then the AGN activity must be turn oﬀ due to lack of the fueling sources.
So far; such a possible process has never been considered. Here; we investigate whether or not a galaxy merger can
strip torus-shaped gas; considered as fueling source; surrounding an SMBH. Simple one-dimensional analytic model
veriﬁes that the gaseous torus is totally stripped via momentum transfer between the torus gas and the gas of an
infalling satellite galaxy. The results of three-dimensional hydrodynamic simulations nicely conﬁrm simple analytic
estimate quoted above. Furthermore; the results clearly show that the stripping of the torus-shaped gas is signiﬁcant;when the column density of the gas in the infalling galaxy is greater than that of the torus.
Author : Ataru Tanikawa
Title : Merger growth of a massive black hole in a primordial galaxy: conditions for successive merger of multiple
massive black holes
Abstract : We have performed N-body simulation to follow the dynamical evolution of 10 massive black holes(MBHs) in galaxies with diﬀerent 3 dimensional velocity dispersions. We include post-Newtonian gravity up to 2.5
order in MBH-MBH interactions; and give gravitational recoil to merger remnants of MBHs. The gravitational recoil
velocity is several hundreds km/s. We have found that 4 - 6 MBHs merge successively to one dominant MBH within
1 Gyr in galaxies with velocity dispersions more than 200 km/s. On the other hand; only 3 MBHs merge in agalaxy with velocity dispersions with 120 km/s. Since galaxies with larger velocity dispersion have larger stellar massdensity; MBHs receive dynamical friction more strongly; and fall more easily into the galactic center where MBHs
merge. Furthermore; we discuss footprints of successive mergers of MBHs. Galaxies which experience such successive
mergers have the feature that high-velocity stars are formed intermittently; in contrast to their constant formation ingalaxies with only two MBHs.
Author : Takanobu Kirihara
Title : Galaxy Collision and the Outer Density Proﬁle in Andromeda Galaxy
Abstract : Recent theory of the structure formation in the universe using cosmological N-body simulations predicts
that cold dark matter (CDM) halos have a universal mass-density proﬁle (Navarro; Frenk & White 1995; Fukushige& Makino 1997; Moore et al. 1998). The prediction of the density proﬁle of CDM outer halos decreases with the cubeof the distance from the galactic center. However; so far not much eﬀort has been done to examine this hypothesis.
Recent observation discovers a giant stellar stream and stellar shells in the halo of the Andromeda galaxy (M31).
The giant stream extends over 100 kpc from the center of M31; and its spatial and velocity structure was observed
in detail. Then; N-body simulations of a galaxy collision between a satellite dwarf galaxy and M31 nicely reproduced
these structures (Fardal et al. 2007; Mori & Rich 2008; Miki et al. 2010). This giant stellar stream provides anattractive window to explore the structure of outer CDM halo in the Andromeda galaxy. In this study; we follow theapproach of earlier studies (Fardal et al. 2006; 2007; Mori & Rich 2008) in simulating the infall of a massive satellite
into M31. However; we change the density proﬁle of the CDM halo of the Andromeda galaxy. Only for the DM
halo with a density power-law slope of -3 ¡ x ¡ -4.5; the results of simulations successfully reproduce the giant streamand (for a similar but much older collision) the apparent shell structures that are observed in the star count maps.
In other words; our result indicates that the actual density proﬁle of the outer DM halo of the Andromeda galaxy
is a steeper than that of the CDM model. In addition; we also focus on the inner structure of the satellite galaxy.
Our latest simulation shows that the progenitor could be the disk-like galaxy to reproduce the observed asymmetricstructure of the giant stellar stream.

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Author : Ryoji Matsumoto
Title : Global Three-dimensional Magnetohydrodynamic Simulations of Disk Dynamos
Abstract : We present the results of global three-dimensional magnetohydrodynamic (MHD) simulations of accretion disks and galactic gas disks. The initial state is a diﬀerentially rotating gas disk threaded by weak azimuthal
magnetic ﬁelds. We included a whole disk in the simulation region to avoid imposing symmetric or antisymmetricboundary condition at the equatorial plane. In simulations of black hole accretion disks; we applied an MHD code in
cylindrical coordinates based on the HLLD scheme (Miyoshi and Kusano 2005). Numerical dissipation of magnetic
ﬁelds is reduced by applying the 5th-order monotonicity-preserving (MP5) scheme. Numerical results indicate thatthe combination of the magnetic ﬁeld ampliﬁcation by magneto-rotational instability (MRI) and the buoyant escapeof magnetic ﬂux by Parker instability drives cyclic dynamos in the disk; the mean azimuthal magnetic ﬁelds reverse
their direction in time scale of 10 rotation period. The buoyantly rising magnetic loops transport the magnetic energy
from the disk to the halo. In simulations of galactic gas disks; we computed the distribution of the rotation measure
and compared it with observations. Such comparison may reveal the previous magnetic activities of our galaxy.
Author : Alexander M. Beck
Title : Simulating Magnetic Fields in Interacting Galaxies and Forming Galactic Halos
Abstract : We present MHD simulations of the compact galaxy group Stephan’s Quintet as well as simulationsof cosmological Milky-Way like galactic halo formation performed with the N-body / SPMHD code GADGET. The
simulations also include radiative cooling; star formation; supernova feedback and the description of non-ideal MHD.
Within the cosmological simulations; a primordial magnetic seed ﬁeld or a supernova seeded magnetic ﬁeld agglomerates together with the gas within ﬁlaments and protohaloes. There; it is ampliﬁed within a couple of hundred million
years up to equipartition with the corresponding turbulent energy. The magnetic ﬁeld strength increases by turbulent
small-scale dynamo action. The turbulence is generated by gravitational interactions and by supernova feedback.
Subsequently; a series of halo mergers leads to shock waves and ampliﬁcation processes magnetizing the surrounding
gas within a few billion years. At ﬁrst; the magnetic energy grows on small scales and then self-organizes to larger
scales. Magnetic ﬁeld strengths of microGauss are reached in the center of the halo and drop to nanoGauss in the
IGM. Analyzing the saturation levels and growth rates; an analytical model is able to describe the process of magnetic
ampliﬁcation notably well and conﬁrms the results of the simulations.
14:00-15:30 Session 11
Author : Axel Brandenburg
Title : ”Dynamos”
Abstract : Many astrophysical bodies (for example the Sun or the Milky Way) consist of hot ionized gas which iselectrically conducting. Such ﬂows are also turbulent. However, a purely hydrodynamic turbulent state can become
unstable to the dynamo instability, so the ﬁnal state becomes magnetized. Signiﬁcant amounts of energy can thenbe converted to and dissipated through magnetic ﬁelds. Numerical simulations show a turbulent forward cascade inwhich the magnetic spectral energy is always slightly larger than the kinetic spectral energy. The ratio of kinetic
to magnetic energy dissipation scales with the magnetic Prandtl number approximately to the 1/2 power, so at low
magnetic Prandtl numbers, most of the energy is dissipated magnetically. This leaves much less energy in the restof the kinetic energy cascade than at unit magnetic Prandtl numbers. Consequently, at given numerical resolution
the viscosity can be lower than otherwise. Simulations show that for isotropically forced turbulence, the so-called
small-scale dynamo exists at magnetic Prandtl numbers down to 0.01.
Next, I will discuss two quite diﬀerent examples in which turbulent hydromagnetic ﬂows can develop spatio-temporal
structures on scales much larger and longer than those of the turbulence. The ﬁrst example is what is sometimes
referred to as a mean-ﬁeld or large-scale dynamo, which requires ﬁnite helicity of the ﬂow. Since magnetic helicity
is conserved in the limit of high electric conductivity, it is driven preferentially to larger scales. This process can bemodeled quantitatively in terms of averaged equations in which the magnetic diﬀusivity is renormalized and othernew terms (e.g. the alpha eﬀect) appear.
The second example is about a process that is now sometimes referred to as negative eﬀective magnetic pressure
instability. In this case the magnetic pressure gets renormalized and can become negative. This process is general andexists even in isotropic non-helical turbulence. However, when it is applied to a strongly stratiﬁed gas with an applied
uniform magnetic ﬁeld, an instability develops that leads to magnetic ﬂux concentrations on scales encompassingthat of at least ten turbulent eddies. The physics behind this is straightforward: as the magnetic ﬁeld is increased,
it increases the magnetic pressure, but it also suppresses the turbulent pressure, and this eﬀect can be stronger,
rendering the total magnetic eﬀect a negative one.
These two examples illustrate the general principle by which the consideration of averaged equations can lead to new8insights with quantitative predictions that are then also borne out by direct numerical simulations. Other dramatic
examples include the turbulent pumping of passive scalars and angular momentum transport even for rigid rotation.
An important application of such considerations are simulations of the solar dynamo. The principle problems faced
so far include a proper understanding of the cycle period and the equatorward migration of its magnetic activity belts
at low latitudes. While simulations are now beginning to reproduce such behavior of the Sun, we are still struggling
to provide tenable explanations for what is now obtained in simulations.
Author : Youhei Masada
Title : Mean Field Generation in Local Convective Dynamo Simulation
Abstract : We study three dimensional dynamics of convection zone coupled with stably stratiﬁed tachocline bymeans of a local box simulation. It is reconﬁrmed by our numerical study that the networked convection pattern withnarrow downﬂow lanes and broad upﬂow cells is strongly aﬀected by both the latitudinal position and angular velocityof the simulation box: the faster rotation gives the smaller and more inclined convective cells to the rotation axis.
Around the equatorial region; the convective cell is more elongated in the latitudinal direction for the model with thefaster rotation. As was pointed out by Brandenburg et al. (1996); the turbulent magnetic ﬁeld seems to be ampliﬁed
in the whole convection zone by vortical swirling downdrafts. A part of the dynamo-generated magnetic ﬁeld is thensupplied to the stably stratiﬁed tachocline by the downward convective pumping. It is found from our study that themean magnetic ﬁeld; which might be responsible for the coherent sunspot ﬁeld; can be generated in the boundary
layer between the convection zone and the tachocline region (cf. Kapyla et al. 2009). In this meeting; we will explain
the properties of the generated mean ﬁeld in detail and will present its dependence on the physical parameters; suchas the angular velocity; the latitudinal position and the strength of thermal stratiﬁcation of the system.
Author : Federico A. Stasyszyn
Title : Global Mean Field Dynamo simulations with SPMHD
Abstract : Following the developments in SPMHD we implemented the turbulent transport terms in the induction
equation for the evolution of the magnetic ﬁeld in; with the aim to perform realistic modelling of dynamo action
in global galaxy simulations. Besides the spatial dependent turbulent diﬀusion η also the α-tensor is included. Fora disk setup we verify our numerical results with a known analytical model of Meinel 1990. Further comparisonswith grid based numerical simulations for disks with a galactic rotation law and an anisotropic α-eﬀect are shown.
Additionally; an accurate method for measuring local turbulence as been implemented. This allow us to perform
global galaxy simulations with a simple subgrid models accounting for the dynamo action; which can be linked toupcoming and present day radio observations.
15:50-17:35 Session 12
Author : Lin-Ni Hau
Title : ”Magnetic Reconnection in Space Plasmas”
Abstract : One of the most important discoveries obtained from in-situ measurement of solar system plasma andmagnetic ﬁeld is the magnetic reconnection which may occur in the solar wind, at planetary magnetopause andmagnetotail as well as heliopause etc. For the past half century substantial eﬀorts have been made on the theory,
simulation and observation of magnetic reconnection which remains to be one of the most outstanding research areasin space and laboratory plasmas. The Earth s magnetopause separating two diﬀerent origins of magnetized plasmas
is an ideal site for the occurrence and study of reconnection physics due to its accessibility to spacecraft measurement.
In this talk a brief overview is presented of the physics of magnetopause current and reconnection in the context oftheory and observation.
Author : Hoonkyu Kim
Title : Inverse Energy Cascade and Imbalanced Magnetohydrodynamic Turbulence
Abstract : Electron magnetohydrodynamic (EMHD) turbulence provides a ﬂuid-like description of smallscaleagnetized plasmas.ost EMHD turbulence studies consider alancedEMHD turbulence; in whicho magnetic helicity
is injected. In this study; we numerically study mbalancedEMHDurbulence. When magnetic helicitys injectedt ascale; we expect toave inverse cascade of magnetic helicity; as well as magnetic energy; in three-dimensional (3D)
EMHDurbulence. We injectagnetic helicity inhree diﬀerent ways: (1) maximal magnetic helicity injection; (2) partial
magnetic helicity injection; and (3) no magneticelicity injection. For no helicity injection; we do not observe inverse
energy cascade. However; when partial or maximal helicity is injected; inverse cascade of magnetic helicitys clearlyobserved . Magnetic energy also show inverse cascade. InMHD turbulence; it is well known thathe magnetic energyn
scales smaller than the energy injection scales direct-cascading quantity and the magnetic energy spectrum follows
a k −7/3 one. On the other hand; the inverse-cascading entity on scales larger than the energy injection scale is9uncertain. Ifhe magnetic helicitys inverse-cascading quantity; we will obtain a k −5/3 magnetic energypectrum. In
our simulations; we do observen energy spectrum consistant with k −5/3 on large scales. Therefore; we conﬁrm thatmagnetic helicity indeed ishe inverse-cascading entity in 3D EMHD turbulence.
Author : Hyunju Yoo
Title : Eﬀects of forcing scale on MHD turbulence
Abstract : Turbulence is ubiquitous in astrophysical ﬂuids such as the interstellar medium (ISM) and the intracluster
medium (ICM). There are many driving mechanisms which can inject energy into the ﬂuid on variety of scales. In areal astrophysical ﬂuid; it is likely that multiple driving mechanisms act on diﬀerent scales simultaneously. Therefore;
understanding diﬀerent statistical properties between turbulence with single forcing scale and turbulence with double
forcing scales is required. In this work; we perform 3-dimensional incompressible/compressible; magnetohydrodynamic(MHD) turbulence simulations. We drive turbulence in Fourier space in two wavenumber ranges; 2¡k¡3 (large scale)and 15¡k¡26 (small scale). We control energy injection rates by changing the amplitudes of forcing in these ranges.
We present time evolutions of kinetic and magnetic energy densities and spectra of density; velocity and magnetic
ﬁelds. We also examine second-order structure function of polarization angle.
Maarten Baes 3D dust radiative transfer in galaxies
Radiative transfer plays a central role in astrophysical research: virtually all information of astronomical objects istransported to us by radiation; but dust particles; omnipresent in many astrophysical environments; are extremely
eﬃcient in absorbing; scattering and re-emitting this radiation. The radiative transfer problem is one of the few
grand challenge problems in computational astrophysics due to its high dimensionality and the underlying integrodiﬀerential transport equation. We present an overview of the recent advancements in developing eﬃcient 3D Monte
Carlo radiative transfer codes. We focus on the SKIRT radiative transfer code; a state-of-the-art tool developed tomodel the interstellar medium in galaxies and the dusty tori around active galactic nuclei. We present our new 3Dclumpy torus models; as well as detailed panchromatic models for nearby edge-on spiral galaxies ﬁtted to a large
panchromatic data set.
Thursday, Nov. 1st
10:30-11:00 Session 13
Author : Ralf Klessen
Title : Star Formation Throughout the Cosmic Ages
Abstract : Stars and star clusters are the fundamental visible building blocks of galaxies at present days as well as
in the early universe. Identifying the physical processes that initiate and regulate stellar birth in our Milky Way cantherefore contribute signiﬁcantly to our understanding of star formation at high redshifts.
Today, stars form by gravoturbulent fragmentation of interstellar gas clouds. The supersonic turbulence ubiquitously
observed in Galactic molecular gas generates strong density ﬂuctuations with gravity taking over in the densest andmost massive regions. Collapse sets in to build up stars and star clusters. Turbulence plays a dual role. On global
scales it provides support, while at the same time it can promote local collapse. Together with the thermodynamic
properties of the gas it regulates the fragmentation behavior in star forming clouds.
I discuss our current understanding of present-day star formation and speculate about the implications for theﬁrst and second generation of stars in the universe. Special emphasis lies on the distribution of stellar masses andtheir dependency on metallicity. I argue that the characteristic stellar mass is roughly constant for a wide variety ofenvironmental conditions and that we expect a transition towards higher masses for metallicities below about 10− 5times solar due to dust cooling. I deﬁne the dominant fragmentation processes at diﬀerent metallicities and speculatethat the masses of zero-metallicity stars were smaller than previously thought and that even the very ﬁrst stars in
the universe formed as members of multiple stellar systems or small clusters.
Author : Tomoaki Matsumoto
Title : Protostellar collapse of magneto-turbulent cloud cores: formation of protoplanetary disks and outﬂows
Abstract : Protostellar collapse of magneto-turbulent cloud cores: formation of protoplanetary disks and outﬂows We
investigate formation of protoplanetary disks and outﬂows inside collapsing turbulent molecular cloud cores by resistive
MHD simulations. By using a self-gravitational adaptive mesh reﬁnement (AMR) code; SFUMATO; the collapse of
the cloud core is followed in a wide dynamic range; we resolve both a cloud cores scale and a protoplanetary disk
scale. A protostar is modeled with a Lagrangian sink particle. The resistivity yields the ohmic dissipation; which
is solved by an implicit scheme. We followed collapse of the turbulent molecular cloud cores and accretion onto
the protostars (sink particles) up to 1000 yr after the protostar formation. The simulations show that the strong
turbulence and weak magnetic ﬁelds promote a relatively rapid growth of a protoplanetary disk around the sink

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particle. The strong magnetic ﬁeld models exhibit the cavities in infalling envelopes around the protostars. All themodels exhibit protostellar outﬂows.
11:20-12:20 Session 14
Author : Ruben Krasnopolsky
Title : ”Formation of Protostellar Disks”
Abstract : The formation of rotationally supported disks (RSDs) is a crucial event of the early times of starformation.
There are theoretical diﬃculties in forming rotationally supported disks during the protostellar collapse of magnetized dense cores. It is often expected that disks would form automatically out of the collapse of rotating cores becauseof angular momentum conservation. In the presence of the observed level of magnetic ﬁelds, this simple explanation
is no longer guaranteed to work, because of magnetic braking and magnetic instabilities. Indeed, in the simplest
case of the ideal MHD limit, both analytic work and numerical simulations showed that RSD formation is completely
suppressed by excessive magnetic braking. Our axisymetric simulations have shown recently that non-ideal MHD
eﬀects (including Ohmic dissipation, ambipolar diﬀusion and the Hall eﬀect) do not weaken the magnetic braking
enough to enable RSDs to form under typical cloud conditions. Nevertheless, RSDs are observed around at least more
evolved young stellar objects and have to form sooner or later.
I will discuss possible resolutions to this problem, including non-axisymmetic magnetic interchange instabilities
in 3D, misalignment of magnetic ﬁeld and rotation, enhanced magnetic diﬀusivities (perhaps due to turbulence orreconnection), and outﬂow stripping of the protostellar envelope, and comment on the apparently discrepant resultsin the literature on this important topic of the early epoch of star formation.
Author : Kengo Tomida
Title : Formation of Protostellar Cores and Circumstellar Disks
Abstract : We perform 3D nested-grid radiation magnetohydrodynamic simulations of protostellar collapse withand without the Ohmic dissipation. We follow the evolution from molecular cloud cores to protostellar cores. In
the ideal RMHD models; the evolution of the protostellar core is very similar to that in the spherically symmetric
non-rotating model due to the eﬃcient angular momentum transport. However; if the resistivity presents; the angularmomentum transport is considerably suppressed due to the redistribution of magnetic ﬂux; and rotationally-supported
circumstellar disks are rapidly built up in the vicinity of the protostellar cores. In the resistive models; two diﬀerent
types of outﬂows are launched from diﬀerent scales due to the interaction between magnetic ﬁelds and rotation; slow
loosely-collimated outﬂows from the ﬁrst cores; and fast well-collimated outﬂows from the protostellar cores.
Author : Kohji Tomisaka
Title : Expected Observations of Star Formation Process: from Molecular Cloud Core to First Hydrostatic Core
Abstract : We did MHD simulations of the contraction of rotating; magnetized molecular cloud cores. In themolecular cores; B-ﬁeld and angular momentum (J) vector are not always aligned. When a ﬁrst hydrostatic core
forms; axisymmetric structure appears and average B and J are parallel in small scale. However; in large scale; theconﬁguration is far from this. This means that contraction process is imprinted on the snapshot. We calculated
two mock observations of MHD simulations (1) the polarization from dust thermal emission to reveal the magnetic
evolution and (2) the line emissions from interstellar molecules to reveal the evolution of density and velocity. Comparing the mock observations with true ones; we can answer several questions: in which case the hourglass-shaped andS-shaped magnetic ﬁelds are seen; how the distribution of polarized intensity is understood; how the ﬁrst hydrostatic
core should be observationally identiﬁed.
13:40-15:25 Session 15
Author : Ing-Guey Jiang
Title : Debris Disks and Planetary Systems
Abstract : The formation and evolution of planetary systems have always been interesting and important topics;
particularly after many extra-solar planets being discovered. Debris disks do not only play vital roles during theformation and evolution of planetary systems; but also act as a useful visible tool to provide hints for other invisible
components in planetary systems. I will review what has been done so far and discuss what could be done in the near
future to advance our knowledge in this ﬁeld.
Author : He-Feng Hsieh
Title : On the secular behavior of dusts in an eccentric protoplanetary disk with an embedded massive planet

11
Abstract : We investigate the dust velocity and spacial distribution in an eccentric protoplanetary disk under thesecular gravitational perturbation of an embedded planet of about 5 Jupiter masses. We employ the FARGO code
to obtain the 2-dimensional gas proﬁle; and then use the secular perturbation theory with gas drag to estimate thedust perturbed proﬁle on the secular timescale. In the model with the planet at 5AU; we ﬁnd that dusts smaller than
one meter behave similarly to the gas and exhibit non-axisymmetric dynamics. However; for the case of 100 AU; a
low-density gaseous disk; the azimuthal distributions of dust of various sizes can deviate signiﬁcantly.
Author : Akimasa Kataoka
Title : Static Compression Process of Dust Aggregates in Protoplanetary Disks
Abstract : Planetesimal formation process in protoplanetary disks is a key issue in planet formation. Recently;internal density evolution of dust aggregates with collisional compression has been proposed to solve this problem(Okuzumi et al. 2012). However; other compression processes; which are caused by gas drag or self gravity; havenot been considered. Such compression processes may diﬀer from collisional compression processes; and thus it may
greatly aﬀect internal density evolution of dust aggregates. Therefore; we investigated static compression processesof porous aggregates by calculating N-body simulation with considering direct interaction forces (Wada et al. 2007);and we determine the equation of state of porous aggregates.
Author : Eiichiro Kokubo
Title : The ﬁnal stage of terrestrial planet formation
Abstract : The ﬁnal stage of terrestrial planet formation is known as the giant impact stage where protoplanets
collide with one another to form planets. We derive an accretion condition for protoplanet collisions in terms of impact
velocity and angle and masses of colliding bodies; from the results of numerical collision experiments. We adopt thisrealistic accretion condition in N-body simulations of terrestrial planet formation from protoplanets and compare theresults with those with perfect accretion and show how the accretion condition aﬀects terrestrial planet formation.
We ﬁnd that in the realistic accretion model; about half of collisions do not lead to accretion. However; the ﬁnal
number; mass; orbital elements; and even growth timescale of planets are barely aﬀected by the accretion condition.
For the standard protoplanetary disk model; typically two Earth-sized planets form in the terrestrial planet region
over about 100 Myears in both realistic and perfect accretion models. We also ﬁnd that typically 10-30% of the total
protoplanet mass is released as collisional debris in this stage. We demonstrate that if the debris is distributed locallyaround a planet orbit; the orbital eccentricity of the planet can be damped to 0.01 through dynamical friction fromthe debris in 100 Myears.
15:45-17:00 Session 16
Author : Hyunjin Cho
Title : Density Distribution Functions in Supersonic Turbulence
Abstract : We study the properties of supersonic turbulence; using isothermal 3D MHD simulations and 13CO line
observations of Galactic molecular clouds. We ﬁrst calculated the density Probability Distribution Functions (PDFs)
both in Position-Position-Position (PPP) space and in Position-Position-Velocity (PPV) space for the simulated
turbulence; driven with a wide range of sonic Mach number and plasma beta. The simulated PDFs follow the lognormal distributions and their variances scale with the sonic Mach number. We then estimated the PDF variances andthe Mach number of turbulence in the molecular clouds identiﬁed in the Galactic Ring Survey. The observed density
PDFs in PPV space are not consistent with the scaling relation; which was derived from the numerical simulations.
We suggest that the turbulence driven on small scales and the gravitational contraction of molecular clouds may
explain this discrepancy.
Author : Tsuyoshi Inoue
Title : Formation of Turbulent and Magnetized Molecular Clouds
Abstract : Using 3D MHD simulation with the eﬀects of radiative cooling/heating; chemical reactions; and thermal
conduction; the formation of molecular cloud is studied. We consider the shock compression of HI clouds as a triggerof the molecular cloud formation; as suggested by recent observations. We ﬁnd that the formed molecular cloudis very turbulent whose size-velocity dispersion relation is consistent with observations. We also ﬁnd that dense
molecular clumps in the cloud evolve toward magnetically supercritical cores via clump-clump collisions. Our results
may provide a typical initial conditions of star formation.
Author : Elizabeth Tasker
Title : How to kill a GMC
Abstract : What controls the life expectancy of a giant molecular cloud is a hotly debated subject. One view is12that supernovae blow away the surrounding gas. Other opinions suggest this mechanism occurs too late; and earlier
feedback is responsible for cloud destruction. This talk presents results from a high resolution (¡ 10pc) numericalsimulation of a global Milky-way type galaxy which includes thermal feedback. We follow the evolution of the GMCs
as they interact in the disc; form stars and undergo supernovae-type thermal energy injection. At the end; we postulate
which of the events occurring in their lifetime dominates their evolution.
Author : Ui-Han Zhang
Title : Nonlinear instability of the cold cloud in a two-phase interstellar medium
Abstract : Usually; the interstellar medium can be regarded as a two-phase ﬂuid. Dense cold molecular cloudsof soft equation of state are immersed in a sea of hot gas of hard equation of state. Hence; the sonoluminescencemechanism can occur in such an environment. That is; a small amplitude sound perturbation in the hot gas canbe greatly ampliﬁed when propagating onto the cold cloud; thereby forcing the Jeans stable cloud to collapse. In
this work; we investigate this novel mechanism numerically with the adaptive-mesh-reﬁnement scheme. Armed with
the GPU-accelerated code; GAMER[1]; we are able to search for the parameter space for the nonlinear-instability
boundary. [1] Schive; H.; Tsai; Y.; & Chiueh; T. (2010). GAMER: a graphic processing unit accelerated adaptivemesh-reﬁnement code for astrophysics. ApJS; 186; 457.
Author : Yuta Asahina
Title : Magnetohydrodynamic Simulations of the Formation of Molecular Clouds in Our Galactic Center
Abstract : We carried out magnetohydrodynamic (MHD) simulations to reveal the formation mechanism of molecularcolumns observed in the central region of our galaxy. These molecular clouds can be formed by the interaction of amagnetic tower jet with the interstellar gas. When the jet collides with dense neutral hydrogen (HI) clouds; the HI
gas is compressed by the bow shock ahead of the jet. Since the density enhancement triggers the cooling instability
because it increases the cooling rate; the shocked gas cools down and forms cold; dense gas. We carried out MHD
simulations including the cooling. The magnetic loops emerging from the accretion disk around the central black hole
are twisted by the diﬀerential rotation at the footpoints of the loops. Numerical results indicate that the magnetic
loops expand; and form a magnetic tower. When the ambient density is small; the propagation speed of the tower
can be as large as the rotation speed of the disk. When the jet collides with the HI cloud; it triggers the formationof the molecular column. The magnetic tower rotates with the rotation speed of the disk. On the other hand; therotation speed of the dense molecular column is much smaller.
Friday, Nov. 2nd
9:30-10:45 Session 17
Author : Junichiro Makino
Title : ”High Performance Computing for Cosmological Simulation”
Abstract : TBA
Author : Tomoaki Ishiyama
Title : The Gravitational Trillion-Body Problem on K computer
Abstract : The ﬁne structure of dark matter halos is very important for dark matter detection experiments. The
mass of the smallest dark matter structures in the Milky Way is predicted to be comparable to the earth mass; which
is 18 orders of magnitude smaller than that of the Milky Way. In order to reveal such ﬁne structures; extremely
large simulations are demanded. However; developing a highly-scalable simulation code is not a trivial task. Our
massively parallel code for large gravitational N-body simulations can address the scientiﬁc requirements. We used the
hybrid TreePM method; in which the short-range force is calculated by the tree algorithm; and the long-range force issolved by the particle-mesh algorithm. We developed a highly-tuned gravity kernel for short-range forces; and a novelcommunication algorithm for long-range forces. We present the implementation in detail and report performance
results of cosmological N-body simulations of one trillion particles performed on the full system of K computer. The
average performance on 24576 and 82944 nodes of K computer are 1.53 and 4.45 Pﬂops; which correspond to 49%
and 42% of the peak speed.
11:05-12:35 Session 18
Author : Jae-Min Kwon
Title : ”Gyro-kinetic Code and Prospect for Astrophysics”

13
Abstract : TBA
Author : Yosuke Matsumoto
Title : Electron accelerations at high Mach number shocks: Two-dimensional Particle-in-Cell simulations on massively parallel supercomputer systems
Abstract : We present the results of global three-dimensional magnetohydrodynamic (MHD) simulations of accretion disks and galactic gas disks. The initial state is a diﬀerentially rotating gas disk threaded by weak azimuthal
magnetic ﬁelds. We included a whole disk in the simulation region to avoid imposing symmetric or antisymmetricboundary condition at the equatorial plane. In simulations of black hole accretion disks; we applied an MHD code in
cylindrical coordinates based on the HLLD scheme (Miyoshi and Kusano 2005). Numerical dissipation of magnetic
ﬁelds is reduced by applying the 5th-order monotonicity-preserving (MP5) scheme. Numerical results indicate thatthe combination of the magnetic ﬁeld ampliﬁcation by magneto-rotational instability (MRI) and the buoyant escapeof magnetic ﬂux by Parker instability drives cyclic dynamos in the disk; the mean azimuthal magnetic ﬁelds reverse
their direction in time scale of 10 rotation period. The buoyantly rising magnetic loops transport the magnetic energy
from the disk to the halo. In simulations of galactic gas disks; we computed the distribution of the rotation measure
and compared it with observations. Such comparison may reveal the previous magnetic activities of our galaxy.
Author : Yipeng Jing
Title : A new subhalo ﬁnder: Hierarchical Bound-Tracing code
Abstract : We develop a new code; the Hierarchical Bound-Tracing (HBT for short) code; to ﬁnd and trace dark
matter subhalos in simulations based on the merger hierarchy of dark matter halos. Application of this code to a recent
benchmark test of ﬁnding subhalos demonstrates that HBT stands as one of the best codes to trace the evolution
history of subhalos. The success of the code lies in its careful treatment of the complex physical processes associatedwith the evolution of subhalos and in its robust unbinding algorithm with an adaptive source subhalo management.
We keep a full record of the merger hierarchy of halos and subhalos; and allow growth of satellite subhalos throughaccretion from its subordinate subhalos in the merger hierarchy hence allowing mergers among satellites. Local
accretion of background mass is omitted while re-accretion of stripped mass is allowed. The justiﬁcation of thesetreatments is provided by a case study of the life of individual subhalos and by the success in ﬁnding the complete
subhalo catalog. Dependence of this tracing algorithm on the time resolution of simulation outputs has also been
examined. We compare our result to other popular subhalo ﬁnders and show that HBT is able to well resolve subhalos
in high density environment and keep strict physical track of subhalos’ merger history. HBT also features its fast
speed as it does not need density interpolation or spatial searching when constructing source subhalos; and because
it is fully parallelized.
14:00-15:30 Session 19
Author : Dongwook Lee
Title : A Solution Accurate, Eﬃcient and Stable 3D Unsplit Hydro/Magnetohydrodynamics Solvers in FLASH
Abstract : In this talk; I will focus on a new set of two unsplit solvers in FLASH for hydrodynamics and magnetohydrodynamics (MHD). The new unsplit solvers follow the basic ideas of the 2D corner-transport-upwind (CTU)
unsplit algorithm by Colella and its 3D full CTU extension by Saltzman. The key diﬀerence in the unsplit algorithm
is to implement transverse ﬂuxes that stabilize an unsplit hyperbolic system without solving separate intermediate
Riemann problems. The scheme instead uses multidimensional characteristic tracing to account for the stabilizing
transverse ﬂuxes; only requiring three Riemann solves in 3D rather than 12 Riemann solves in the full CTU scheme.
The new 3D unsplit solvers provide a CFL limit close to unity. I will also talk about a new constrained transport (CT)MHD algorithm that evolves divergence-free magnetic ﬁelds using an upwind biased electric ﬁelds constructon. This
upwind scheme is crucial to advect magnetic ﬁelds when there is a dominating direction for advection. Lastly; I will
give an overview on the ongoing eﬀorts to simulate high-energy-density physics experiments to explore the generationof cosmological magnetic ﬁelds via the Biermann Battery mechanism.
Author : Tomoyuki Hanawa
Title : Reconstruction Method for Solving M1 Equations for Radiative Transfer
Abstract : We propose a new method to construct numerical ﬂux for the M1 equations of radiative transfer. The
numerical ﬂux is expressed as an explicit function of the energy density (E) and ﬂux (F). It is constructed from theintensity distribution consistent with the closure relation. It has the upwind propoerty in the sense that the solution
is guranteed to be physical (—E— ¿ c —F—) as far as the CFL condition is satisﬁed. We apply this method toan irradiated protoplanetary disk. The model reproduces spectral energy distribution (SED) for a transitional disk
having an inner hole. Our model takes account of heating of the inner hole by irradiation from the disk wall.

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Author : Hanbyul Jang
Title : A Relativistic Magnetohydrodynamic Code Based on an Upwind Scheme
Abstract : Building a code based on upwind schemes for numerical relativistic magnetohydrodynamics (RMHD) has
been a challenging project; because of the absence of analytic expressions of eigenvalues and eigenvectors. For adiabatic
RMHD ﬂows; We obtained analytic expressions of eigenvalues and renormalized sets of right and left eigenvectors;
which are relatively simple and manageable. Using these analytic forms; we built a code based on the total variation
diminishing (TVD) scheme; and successfully performed one-dimensional shock tube tests.
Author : Tsungche Liu
Title : Web-based Cloud Computing for High Energy Neutrino Simulation
Abstract : The monte-Carlo code for the high energy neutrinos and leptons are developed; the code simulates
the neutrinos and leptons interating with several kind of materials; such as rock; ice; air; iron and water. User can
speciﬁy their experiment setup to generate the neutrino event and easy to link to the other program. The web version
simulation code are developing now; user could submit his job on web; and get the preliminary result from e-mail.
mod
Author : Hung-Hsu Chan
Title : A New Method for Computation of Self-Gravity in an Isolated System
Abstract : The gravity of isolated system has so far been eﬃciently solved by the modiﬁed Green’s function method
via Fast Fourier Transform (FFT). However; this method; in three dimensions; entails 8 times larger volume for the
FFT computation; which can be not only memory consuming but also computationally expensive. We propose analternative method based on multipole expansion; which is computationally economic. This method generally yields
an error greater than that with the modiﬁed Green’s function. However; in some relatively symmetric system; thepresent method can yield an error much smaller than the modiﬁed Green’s function method.