Download Search for Student Research Assistant

Search for Student Research Assistant
I’m looking for a student research assistant or two for Fall 2015 semester. It is possible that further
research work could go on the student’s transcript. The research may lead to publication in a journal or
presentation at a conference.
Prerequisites: Currently in 2nd semester of Intro Astronomy, or on a calculus-based physics track. Ability
to program computers is a plus.
Skills to pick up on the project: Use of Unix or Linux computer operating system. Programming in
Mathematica or IDL languages.
Projects Available:
1) Designing a “Citizen Science” site. We use citizen science sites in Astronomy Lab. For a taste, go
to http://www.zooniverse.org The idea is that regular people can be very useful to astronomers
by categorizing data over the internet. Computers are still not very good at recognizing patterns.
That is why when a website needs you to prove that you are a human being and not a program
using the site, you will be given a “Capcha” image and have to read the distorted letters. For
example, within the “Zooniverse” was something called the “Galaxy Zoo” that showed images of
galaxies seen with the Hubble Space Telescope to users over the internet. What I imagine us
doing is creating a site where users can help us understand the flickering of X-rays around black
holes by helping to recognize where each oscillation starts and stops. I’m particularly interested
in the data of the black hole system GRS 1915+105.
2) Entering a “Big Data” contest on Kaggle.com. One contest in particular involves computer
methods to make discoveries about the basic particles of nature. The contest is called “Flavours
of Physics: Finding , and you can have a look at the site here:
https://www.kaggle.com/c/flavours-of-physics
There is a total of $15,000 awarded for those who do very well on this contest. Basic summary:
we will use data from the Large Hadron Collider, humanity’s most advanced particle experiment.
Just as there are electrons in atoms, there is a possibility of a heavier, similar particle called a
muon, or There is a still heavier particle called  or tau. We will develop some advanced
computer programs to find evidence for a particular reaction in nature where a tau particle
breaks apart into three muons.
3) Flickering radiation from a dead star may reveal details of the gas flowing around it. Scorpius X-1
(Sco X-1 for short) is a double star system. It’s actually the brightest spot in the sky in X-rays
(other than the Sun). Of the two stars, one is a normal star, slightly less massive than our own
Sun, but the other is a neutron star (a collapsed star only about 10 km across). Sco X-1 was the
first discovered star system of its type. It is particularly interesting because although it has a
neutron star, no pulsations have been seen. It is the brightest of a class of neutron star systems
called ``Z sources”.
What is the project and what would the student do? In August, ultraviolet observations from the
Hubble Space Telescope of this star system became public. The main investigator told me he is
looking to study the gas in front of the star, and not the star itself, so that we are not duplicating
his effort. I have a plan to study how the ultraviolet spectrum of the star itself is changing. There
is a very small chance we could discover pulsations from this star system, never seen before, but
there is also very interesting flickering “noise” that we could measure and compare at different
times and wavelengths. This project would involve learning and using the IDL programming
language and learning “time series analysis” and “Fourier transforms and power spectra” which
are useful in many fields of science, mathematics, and economics. More information: technical
paper my team wrote on Hubble data 10 years ago, http://iopscience.iop.org/0004637X/502/1/441/pdf/36461.pdf. Paper on Fourier techniques of time-series analysis:
http://dl.dropbox.com/u/8721683/Fourier_techniques.pdf. PowerPoint summary of Fourier
techniques in time series analysis: http://pulsar.sternwarte.uni-erlangen.de/blackhole/2ndschool/talks/amsterdam_ITNschool_2010.pdf.
4) A method to figure out which X-ray stars are black holes and which are neutron stars. A
collaborator of mine at Harvard has an idea for a way to find out, from the varying spectrum of a
star in X-rays, whether it is a neutron star or a black hole. The method is a little similar to the “HR diagram” taught in Astronomy 1020. Two kinds of colors are plotted for each star at each time
along with the apparent brightness, for a 3D plot. We are using the Mathematica software to
make 3D plots we can see from different angles. We have already applied the method to X-ray
stars in the Milky Way and nearby galaxies, but now we want to use it on galaxies further away.
The student who works on this project will have to pay close attention to computer files that
record the brightness of X-ray stars in different X-ray colors. We will have to put together data
from different forms to make these 3-dimensional plots. More information: http://heawww.harvard.edu/~saku/SED.html This project does NOT require ability in advanced math
techniques, only finding ways to organize and present data. A student could also go a little
further and work with me on making a theory of why the method seems to work.
5) Cygnus X-1 is a star system that very probably contains a black hole feeding off a normal massive
star. I have been working with a student to understand dips in X-rays coming from the star
system periodically along with the orbit of the two stars. The dips tell us about gas flowing in the
system. The black hole can be in different “states” of brightness and the gas flows can be
affected based on what state of X-ray brightness the black hole is in. Let’s try to compute
theoretically how the gas might flow and compare with the observed dips. Starting with some
publically available programs (probably in FORTRAN) we can modify the program to study how
the gas flows in a binary star system, influenced by gravity, by heating, and by ionization from an
X-ray star. This is a potentially challenging project both for the student and for me. There would
be an advantage if we could hook up several computers to work on the problem at the same
time. This would be a very challenging project (for both student and myself). The student would
learn computational hydrodynamics.
6) Helping to make some preliminary studies and writing a proposal to observe the star system
Centaurus X-4. This is a binary star system with a normal star and a neutron star. What’s unusual
here is that the gas flow is very weak. Only every once in a while does it turn up to strong steady
gas flow and the X-rays become bright. We’re trying to understand what happens at low gas
flow, because it’s harder to see when it doesn’t light up as much. Does the heat get carried
along with the gas, instead of being released in radiation? What could we see with the Hubble
Space Telescope pointed to observe Cen X-4? There are already some crude observations with
Hubble, but new instruments allow us to see things better.
7) Developing new techniques of “Doppler Tomography”. Doppler Tomography lets one
reconstruct how a binary star system looks from changing spectral lines. This project would
involve programming in Mathematica and could involve either Fourier methods or a data
technique called “Maximum Entropy Reconstruction” or a method borrowed from radio
astronomy called “CLEAN”. We would apply this method to different star systems. Goals are to
test experimental methods to get a 3-dimensional view of the star system (most methods only
get a 2-dimensional view) and to use separate spectral lines to see through the gas.
8) A more “out-there” project is to work on models of quantum physics in which space and time
are not infinitely divisible, but in which there is a discrete smallest possible size or time interval.
I’m offering this project for students who can handle quantum and math concepts and want to
work on something more unusual. There are some physicists who speculate the Planck length
may be a lower bound for size in the universe, and we could work on improving models related
to “the Feynman checkerboard” or the material graphene which explain quantum behavior, but
that are limited in some ways.