Apologies for the slightly delayed blog
post (to all four of you who are still reading this). In my defence, I spent the
entire last week in the Netherlands, giving presentations and attending PhD
interviews. The experience was absolutely brilliant, speaking with some of the
most accomplished scientists and meeting with current PhD students and
applicants from all around the world. It is in situations like these when you
truly realise how similar people from all over the world are, and how you can
strike conversations about absolutely anything and everything with complete
strangers!
Astronomy is one of the top subjects of
research in the Netherlands. This little country is moving mountains to
establish itself as one of the top players in the already vast field of
astronomy and astrophysics. One of the key projects that has truly cemented the
Dutch presence on the world map is the ground-breaking radio telescope called
Low-Frequency Array or LOFAR. LOFAR is said to be the largest connected-telescope
ever built, with data being collected and processed from 48 large stations. 40
of these stations are situated in the Netherlands, 5 are in Germany and one each is in the
UK, Sweden and France. LOFAR enables, for the first time, sensitive observations
from the lowest possible frequencies accessible from the ground, at around 10
MHz up to frequencies of 1400 MHz.
Aerial photograph of the Superterp, the heart of the LOFAR core, from August 2011. The large circular island encompasses the six core stations that make up the Superterp. Three additional LOFAR core stations are visible in the upper right and lower left of the image.
Image and further reading: http://inspirehep.net/record/1233495/plots
The science case for LOFAR is the most
interesting bit. Essentially, one of the main aims is to probe large-scale structure
formation in the early universe. We observe a lot of large clusters of
galaxies, but know very little about how and when they were actually formed.
Galaxy clusters are the largest observed cosmological structures in the
universe, consisting of 100 to a 1000 galaxies held together by gravity. One of
the key features is that these galaxies are ‘embedded’ in a very hot and
energetic intra-cluster medium (ICM). A lot of interesting physical phenomena
are observed in such a setting, which makes their study really exciting.
Another key project of LOFAR is to study
very energetic ‘active’ galaxies. It is now well established that in the centre
of every galaxy lies a supermassive black hole (SMBH). An active galaxy is one
in which the central SMBH is constantly gobbling up mass and wreaking havoc.
Such galaxies exhibit high levels of brightness in almost every order of the
electromagnetic spectrum, be it radio emission, visible light or x-ray
emission. We currently understand very little as to how such active galaxies
appeared in the early universe, how they evolve and what are the processes
involved in such violent environments.
For my master’s project, incidentally, I am
studying these active galaxies as the sources of the very exciting ultra
high-energy cosmic rays (UHECRs). UHECRs have puzzled scientists for decades,
and we currently do not fully understand how such high energies are achieved in
the particles that are constantly bombarding us from outer space. I aim to
write a blog post about it in the near future!
The Netherlands is a beautiful country, with
friendly and welcoming people. The institutes I visited as part of the PhD
selection programme, Leiden Observatory and University of Amsterdam are
absolutely fantastic and are deeply involved with top class research. With LOFAR,
this country is certainly making its presence felt and is pioneering
ground-breaking research, in a hunt to answer the pressing, currently
unresolved problems in astrophysics.
