Research
Senior Thesis
Identifying Type Ia Supernovae in Extragalactic Spectra
Adviser: Prof.
Segev BenZvi, University of Rochester, Rochester NY.
Fall 2017 - Spring 2018
Abstract:
With future astronomical surveys expecting to see millions of transient events per night
(such as LSST), there is a need to develop efficient means of identifying interesting
objects. One such class of interesting objects are type Ia supernovae. I investigate the
optical spectral footprint of type Ia supernovae with the goal of understanding how these
objects may be identified within the spectra of their host galaxies. I describe and compare
several machine learning and data-driven approaches for identifying type Ia supernovae
spectroscopically. Finally, I detail the application of these methods to the Dark Energy
Spectroscopic Instrument (DESI), which will observe 30 million galaxy spectra over the next
ten years and as such is a prime instrument for finding supernovae and other interesting
phenomena spectroscopically.
Thesis Document
Past Projects
Looking for "Fermi Bubbles" in M31
Adviser: Prof.
Segev BenZvi, University of Rochester, Rochester NY.
Fall 2016 - Summer 2017
Description of Research:
The discovery of the "Fermi Bubbles," two large spherical bubbles of high
energy gammaray emission above and below the galactic plane of our own Milky
Way Galaxy, was one of the most unexpected and puzzling discoveries of the last
decade. It is still largely debated what the origin of the bubbles are and what
processes power their energy output. The Milky Way Galaxy is the only known
galaxy for this structure to be observed in gammaray wavelengths, however
recent observations in March 2016 by M. S. Pshirkov et al. have found evidence
supporting the existence of "Fermi Bubblelike" structure around the Andromeda
galaxy (Messier catalog M31), the nearest large spiral galaxy. I am currently
using data from the HAWC observatory to develop and fit a model of the
FermiBubble region to M31 to see if there is any emission from the proposed
bubbles at the TeV energy range. Confirmation of FermiBubbles around M31 would
be a great step towards understanding this astronomical phenomena.
This research was presented at the 35th International Cosmic Ray Conference (ICRC2017) in Bexco,
Busan, Korea. See:
R. Rubenzahl, S BenZvi, and J. Wood, Limits on the Emission of Gamma Rays From
M31 (The Andromeda Galaxy) with HAWC, in Proceedings of 35th ICRC, 2017, 1708.03012.
Poster: Limits on the Emission of Gamma Rays From M31 (The Andromeda
Galaxy) With HAWC
Analyzing TeV Gamma-Ray Binary Candidates with the HAWC Observatory
Adviser: Prof.
Segev BenZvi, University of Rochester, Rochester NY.
Fall 2015 - Present
Description of Research:
Gamma-ray binaries are extrasolar binary systems
that emit gamma-ray radiation. There are two types of such systems:
Microquasars, which consist of a normal O or Be star with a compact,
high-mass comapion, such as a neutron star or black hole. The compact
companion accretes matter from the star, forming an accretion disk and
relativistic jets, which result in the emission of gamma-rays through
particle acceleration and inverse Compton scattering. The other type is
a pulsar binary, which is composed of a normal O or Be type star with a
pulsar (rapidly rotating neutron star) in orbit around it. The interaction
between the pulsar wind and the stellar wind results in particle acceleration
and production of gamma-rays. These systems are characterized by the periodic
output of gamma-rays, due to the orbital nature of these systems. So far
there have only been five binary systems observed in the TeV gamma-ray range:
LS I +61° 303, HESS J0632+057, LS 5039, PSR B1259-63, and 1FGL J1018.6-5856.
The High Altitude Water Cherenkov Gamma Ray Observatory, or HAWC, is an observatory located in Puebla, Mexico that utilizes the water-cherenkov technique to detect gamma-rays. Three of the five known binaries lie in the field of view of HAWC, which is well-equipt to detect periodicity with its high duty cycle and instantatneous 2 steradian field of view. We look to confirm previous observations by other collaborations by observing the gamma-ray binaries LS I +61 303, HESS J0632+057, and LS 5039. These sources should exhibit periodicity in the flux of gamma-rays over time, corresponding to the orbital period of the system. To observe this, we analyze 444 days of data from HAWC between November 26th 2014 to February 12th 2016. We fit a simple power law spectrum to the location of the source at each day and use a maximum likelihood and MCMC calculation to find the integral flux of the source to generate lightcurves of each source. We then use a Lomb-Scargle Periodogram to determine if we observe any periodicity in the lightcurve. The sources LS I +61 303 and HESS J0632+057 are further studied to look for signs of flares and high-states of flux respectively.
So far, we have yet to detect signs of periodicity in the flux as
measured by HAWC. We are currently working on better characterizing the
background emission, modelling nearby sources that contribute to source
confusion, and modelling the diffuse emission by the galactic plane. These
additions will improve our sensitivity and will hopefully result in detecting
periodicity. By confirming these sources as gammaray binaries, we will equip
HAWC with the necessary tools to identify new gammaray binary candidates,
increasing the opportunities to study these rare systems.
Slides: Analyzing TeV Gamma-Ray Binary
Candidates with the HAWC Observatory, Presented for the REU 2016
Final Presentation, and at the UR SPS Summer Research and Internship
Symposium.
This research was presented at the 35th International Cosmic Ray Conference (ICRC2017) in Bexco,
Busan, Korea. See:
C.D. Rho, R. Rubenzahl, and S BenZvi, Searching for TeV Gamma-ray Emission from Binary Systems with HAWC, in Proceedings of 35th ICRC, 2017, 1708.03726.
Simulating Outrigger Tanks around the HAWC Gamma Ray Observatory
Adviser: Prof.
Segev BenZvi, University of Rochester, Rochester NY.
Spring 2015 - Summer 2015
Abstract:
The HAWC Observatory consists of 300 water tanks that detect gamma-rays
through the water-Cherenkov method. Not all air showers produced by gammarays
trigger the full HAWC array. Some showers clip the edge and as such cannot be
reconstructed accurately, and others are missed entirely. To be able to
reconstruct these showers, a sparse outrigger array may be added surrounding
the main HAWC array to collect more information. The purpose of this research
is to determine the optimal design of these outrigger tanks, and the
configuration in which they should be distributed. I used the programs Geant4
and CORSIKA to write c++ code to simulate the responses of various
configurations of tanks to air showers, and measure their ability to
accurately reconstruct events. The optimal tank designs I determined were
submitted to the HAWC collaboration for consideration in the construction of
the outrigger array.
Slides: Simulating Outrigger Tanks Around
HAWC, Presented for the REU 2015 Final Presentation and at the Rochester
Symposium for Physics Students (RSPS), April 2016.