Description of project Universe@home

We live in times which are marked by the fastest scientific development in the history. Our knowledge grows faster than ever before. We explore the structures of the Universe, nuclei of stars and evolution of galaxies. Using the strength of our minds we crack problems that are not tangible and cannot be examined in laboratory. The technology came as an aid in this struggle. The computers help us to calculate complicated problems and to model extraordinary objects. Therefore the need for computational power is growing exponentially in the scientists' community.

In a different situation are millions of people around the world. The computers industry is evolving extremely quickly and personal computers are available for constantly decreasing prises. Simultaneously, these machines must be strong enough to fulfil the growing needs of users who want to play the newest games and use resources-demanding programs. However, most of the time such computers spend in the idle state when they are used for simple web-browsing or document-writing. The most of computational power stays unused.

As a remedy to both these issues have came the BOINC platform. The innovative infrastructure, which, from one side, serves as the source of huge computational power, and from the other side, gives people the possibility to become involved in huge contemporary science projects utilising their limited resources. BOINC stands for Berkeley Open Infrastructure for Network Computing. This system was used for the first time in year 1999 and afterwards dozens of other projects have came into existence. In 2014 the time came for adopting this idea in polish astronomy projects and, at first, the fundamental problems of the stellar evolution will be solved.

BOINC in scientific modelling plays a role of a middleware. Scientists prepare a project which needs a huge computational power and, at the same time, can be divided in small parts that may be run parallelly. A server is prepared and the BOINC infrastructure installed on it. From that moment everyone connected to the Internet can download the special client program. It monitors their computers and if only machine processor is becomes idle, it downloads the data and calculates. There is no hindrance for the user as the computation is reined up every time the computer is needed for something else.

Universe@home project utilises the BOINC platform to perform simulations of evolution of numerous stars. In this way we are able to reproduce the evolution of such stellar populations as whole galaxies consisting of billions of stars. The vast picture that is obtained let the scientists compare the results with all the attainable observational data. Such a massive comparison is far more superior to one made on single system. Investigations made on the whole stellar populations gave us not only the information about their evolution but also about the multiplicity and statistics. This methodology is called population synthesis.

The users who downloaded the client program and chose this project to support, will get a small number of systems. They will calculate the whole evolution of this systems, beginning with the ignition of helium synthesis and ending on the formation of compact object. Then they will return the result to the server. Combining this pieces together a reasonable number will be collected and the analysis will be performed by scientists. Finally, results will be published and will become publicly available. With the development of the project more and more subprojects are going to be available, as the number of different problems, which may be explored in this way, is uncountable. Users will be presented with the possibility to choose which one they want to support at the moment. Every subproject will be described on the project webpage and the users will be informed about the partial results.

The head of the team is prof. Krzysztof Belczyński. He works in the Astronomical Observatory University of Warsaw and cooperates with several research groups worldwide. He is the author of about 200 science papers and he supervised a few students who are currently independent scientists. Professor is the first author and coordinator of the development of the StarTrack population synthesis code which is used for the needs of Universe@home project. The code performs the complex evolution of stars and is kept up-to-date with contemporary development in this field of science. StarTrack was used in dozens of projects and basing on its results hundreds of research papers were published. It is one of the best and widely distinguishable population synthesis codes in the astronomical community.

Below we present a few of problems currently studied by astronomers, which can be approached with the use of Universe@home project.

1) Ultraluminous X-ray Sources (ULX)

ULXs are the point-like sources of a very strong X-ray radiation. Observations show that they are off-nuclear, i.e., they are not a typical stars. ULXs should be distinguished from Active Galactic Nuclei, which are their far heavier cousins residing in the centres of galaxies. We know already nearly 500 ULXs but we still lack the knowledge about their nature. Two most probable explanations are the hypothetical intermediate mass black holes, and typical compact objects but with extremely high mass accretion rates. Recent observations point to the latter. Compact objects like neutron stars and black holes are ubiquitous in the Universe. If they are the engines in ULXs, the fuel is the accreted matter. Scientists thought that such a high accretion rates are unphysical, however, new models show something opposite. The quest is to check them and compare with observational data.

2) Gravitational Waves

This peculiar type of signal was predicted nearly a century ago by Albert Einstein as a consequence of the General Theory of Relativity. Any double compact object (e.g., two black holes or two neutrons stars) should emit such a radiation, which will be visible in gravitational waves observatories. Primary problem is the lack of observations. Their existence is clearly visible in equations but up-to-date there were no signal detection. Our simulations are able to provide a highly realistic estimates of potential observations. When new instruments are becoming operational, it is important to know the predictions. The observational program will be different if we expect one observation daily, then one a year. The StarTrack code, possessing a developed models of compact object formation, is a best tool for making such a calculation and supplying observers with valuable hints.

3) Supernovae Ia

This type of supernova explosion is extremely important for the cosmic distance scale. Thanks to them we were able to estimate the expansion of the Universe and calculate the distances to remote galaxies. Although we know that this explosions are connected with mass accretion onto white dwarf, we still endeavour to learn the explosion mechanism and the evolutionary routes leading to them. Our code, as performing the complex evolution of every binary, is perfect for answering the problem of evolutionary processes leading to supernovae Ia. What is more, we will be able to provide a lot of information about the formation rates, types of donors, and much more. We will be able to test several model proposed by the researchers' community and even quantify the influence of this type of supernova on the chemical evolution of the Universe.

The Universe@home is the first project using BOINC infrastructure developed and run in the polish higher education institution. The advanced parallel computing methods are being used for solving contemporary scientific conundrums. This is a great step forward as the method proves to be efficient in multitude of other similar projects abroad.

There is no better way of learning than through experience. Currently, a daily life is left far behind the science achievements, schools rarely teach about current problems in science and we have less and less time for reading. Therefore, it is of high importance to find a way to stay in touch with the development. Univserse@home reconnects people, who don't have time or will to conduct any research, to development in our understanding of the nature. Research is worthless for the society if it is not spread among people. It is very important in contemporary world to renew the presence of development and science in our surroundings.

All results of the project will be publicly available. On our webpage we will post all the information about currently running simulations, published results and technical details. Finally, it is planned to provide a huge data base which will serve as a great research tool for other scientist. We will store all the acquired data about the evolution of stars and stellar systems, thus, profits will expand out of the initial range of problems. What is more, the data base will be open to public and will become a great learning and teaching tool. A work done by volunteers will return to them in such a form.

Although Univserse@home is the first project of its kind in Poland, we believe that it will show the path for other heavily numerical science projects. Currently it is unimaginable to carry out any research without the use of computers. Complicated simulations, data analysis and controlling of huge detectors - in all these fields strong computers are needed. Not once, however, costs of such machines were far beyond the budget. The volunteer computing comes as a remedy here.