The Astrophysical MUltiscale Software Environment (AMUSE)

The Astrophysical MUltiscale
Software Environment (AMUSE)

P
-
I: Portegies Zwart

Co
-
Is: Nelemans, Pols, O’Nuallain, Spaans

Adv.: Langer, Tolstoy, Hut, Ercolano, de Grijs,
Mellema, Spurzem, Bischof, Quillen

AMUSE

The objectives of AMUSE


More science with existing software


Combine existing astrophysical codes


This is a technical problem


It is technically possible


Impression of how it works

Existing codes


Excellent single
-
physics codes exist


hydro


gravity


radiation


stellar evolution


All written in different languages, different
format, different architecture....


Need a homogeneous environment for utilizing
these resources

More science with existing code


Universe is multi
-
physics ...


Scientific objectives:


dense stellar systems (hydro+gravity+stellar evo.)


evolution of galactic environments, star formation,
AGN, ... (hydro+gravity+radiation)


planet formation (hydro+gravity+radiation)


galaxy formation and interaction
(gravity+hydro+radiation+stellar evo.)


Single physics software solutions exist, try to
combine existing codes

This is a technical problem


No new physics needed


Combining requires understanding of how
software and computer hardware interacts


Development to a usefull toolbox requires
professional engineering


Requires substantial manpower

It is technically feasible


Developing new code not optimal because


it is a time consuming task


large codes tend to become unmanageable


initial assumptions tend to require redesign at a late
stage in the development process


Combining existing code via wrapper has been
tried, and works


Propose homogeneous software framework,
à

la Numerical Recipes

Flow control layer (scripting language)

Gas dynamics

Radiative

transport

Stellar evolution

Stellar dynamics

Interface layer (scripting and high level languages)

Smoothed

particles

hydrodynamics

Metropolis

Hastings

Monte Carlo

Henyey

multi
-
shell

stellar evolution

4
th

order Hermite

block timestep

N
-
body

AMUSE

Limitations and Merits

-

Only problems whose physics are expressible
through module coupling (different time scales)

-

Low and high level use possible

-

Radiative transfer (and stellar evolution)
module links to VO (through eg. ‘spiegel’ and
‘partiview’): dust and stellar continuum, atomic
and molecular lines;
ELT, JWST, ALMA, Herschel

Impression of how it works

A)

install

B)

suite of test applications

C)

design your own multi
-
physics problem

D)

write script

E)

run

F)

analyze data

G)

download package from website

H)

write Nature paper

Design/Performance


AMUSE module must be written in language
with Foreign Function Interface (C, C++, Fortran
as well as high level languages like C#, Java,
Haskell. Low level applications optimized.


Top level uses a scripting language. These are
slow, but do just I/O, GUI, call sequence.


Top level can run in parallel (using MPI, GRID
technology); data exchange through HDF


Low level can run in parallel or on dedicated
hardware (eg GRAPE or GPU for direct N
-
body)

Initial Applications


Young and dense star cluster


Evolution of gas and stars near a black hole in
a galactic nucleus


Dynamics of embryonic planets in a debris disk

Relation to other projects


Different concept but with similar scientific
objectives/physics:


FLASH


Gadget


Starlab


Comparable in setup but with different scientific
objectives:


Atmosphere/Ocean/Tectonic
simulations by NASA


Molecular dynamics


QUESTIONS?

management/development plan


programmers under daily supervision of
software engineer and PI


regular interaction with
postdoc, who protects
scientific objectives

The cost


6
-
year of programming effort (3x2years?)


2 years of software engineering


2 years of postdoc


travel, webservices, hardware, etc.


total cost: 640Keuro


NOVA request: 500kEuro