2015

Links to:

    List of colloquium talks given during the summer of 2015 

    Program of the SAO Summer Intern Symposium, August 13, 2015

 
    2015 Summer Program Calendars for June, July, and August 

    Abstracts for posters presented at the January 2016 AAS Meeting 
 

INTERN: Huanqing Chen (Nanjing University)

ADVISOR:Dr. Christine Jones (HEA Division) 
CO-ADVISOR/MENTOR: Dr. Felipe Andrade Santos (HEA Division)

PROJECT TITLE: Identifying Sloshing Cold Fronts in the Galaxy Cluster Abell 2204

Abstract: 
The hot gas in clusters can be perturbed by interactions between clusters. We will investigate the sloshing of the hot gas in the cluster Abell 2204 using deep Chandra observations. In particular, we will determine the locations of sharp discontinuities in the X-ray surface brightness and measure the gas temperature across these regions to test that these are cold fronts due to sloshing and not due to shocks. We will also examine the larger region around the cluster to search for the perturbing system. Finally, we will compare the X-ray morphology with that of other sloshing clusters and with simulations.

INTERN: Erin Fong (Tufts University )

ADVISOR:Dr. Peter Williams (OIR Division) 
CO-ADVISOR: Prof. Edo Berger (OIR Division)

PROJECT TITLE: Measuring Rotation in a Million Very Cool Stars

Abstract: 
Stars are born rotating rapidly but gradually slow down over their lifetimes. There's a great deal of interest in understanding this process because it implies the possibility of "gyrochronology": inferring a star's age, an important and hard to measure quantity, from its rotation rate. Stellar spin-down varies with properties such as mass and metallicity, though, and a key finding is that very cool (low-mass) stars behave strangely: they seem to rotate rapidly for a long time, then spin down suddenly.

The REU student and I will work together to gain insight into this puzzle by measuring rotation periods from photometric data of a sample of about 1,000,000 very cool stars in the Pan-STARRS1 Medium Deep Survey (MDS) data set. I will simultaneously lead a study of flaring in the same stars and our two projects will build on a common target catalog and photometric database that I am constructing. The MDS data set is a unique resource, comprising about 100 TB of data, and the student will learn "Big Data" analysis and statistical techniques in Python while using Harvard's Odyssey computing cluster. The student will write a research paper presenting her or his measurements in a subset of the survey footprint, and our goal will be submission to the Astrophysical Journal.

ADVISOR:Dr. Cara Battersby (RG Division) 
CO-ADVISORS/MENTORS: Drs. Eric Keto and Qizhou Zhang (RG Division)

PROJECT TITLE: Extreme Star Formation in the Center of Our Galaxy

Abstract: 
We are searching for a summer intern to investigate extreme star formation in the central region of our Galaxy. The center of our Galaxy hosts a supermassive black hole and the densest reservoir of molecular gas in the Galaxy. However, the best measurements to date suggest that this region seems to be breaking star formation laws and under-producing stars by about an order of magnitude. Is there a population of newly formed stars missed by previous observations that explains this discrepancy? Can we explain the dearth of star formation by high turbulence or magnetic fields?

The student will collaborate with our Legacy Survey Team working to observe the center of our Galaxy at high resolution and long wavelengths using the Submilimeter Array. Observations from year 1 of the survey are complete, and the student will work with fully calibrated and reduced data from the survey to investigate the properties and star forming activity of clouds in our Galactic Center. This is a relatively unexplored region of the Galaxy, with many mysteries to solve and discoveries to uncover. Understanding how stars form (or why they don't) in such an extreme environment is key to building a global model for the fundamental process of turning gas into stars.

ADVISOR: Dr. Blakesley Burkhart (TA Division)

PROJECT TITLE: A Study of Lyman Alpha Cloud Properties Using the ILLUSTRIS Cosmological Simulation

Abstract: 
The student will analyse formation of low column density structures in the ILLUSTRIS simulation. The work will involve becoming familiar with cosmological N-body simulation techniques and how to use the resulting data products. We hope to improve understanding of the size distribution of Lyman alpha clouds and small galaxies and derive predicted galaxy and cloud properties.

ADVISOR:Dr. Sarah Willis (OIR Division) 
CO-ADVISOR: Dr. Joe Hora (OIR Division)

PROJECT TITLE: Emission Line Imaging in Massive Star Forming Regions

Abstract: 
Young high mass stars pour energy into surrounding molecular clouds, heating the dust and ionizing and eventually dispersing the gas. We have obtained high spatial resolution maps of 6 galactic massive star forming regions with narrow band near-infrared filters that select for ionized BrG at 2.17 microns and molecular hydrogen, H2, at 2.12 microns. These regions have previously identified populations of several thousand young stellar objects. The H2 line is typically excited when high velocity outflows from young stars collide with the surrounding interstellar medium. The student will use continuum-subtracted H2 maps to identify candidate outflows and will identify spatially associated young stellar objects that are candidate driving sources. The student will measure the integrated flux in BrG for each region and calculate a BrG-traced star formation rate. These will be compared to previously determined star formation rates from young star counts and mid-infrared star formation tracers to better understand the overall activity of each region.

ADVISOR: Dr. Atish Kamble (TA Division) 
CO-ADVISOR/MENTOR: Dr. Raffaella Margutti (OIR Division)

PROJECT TITLE: Radio Spectacle from Supernovae in the Local Universe

Abstract: 
Supernovae are among the brightest astronomical sources in the universe. These are the death throes of massive stars giving birth to objects such as white-dwarfs, neutron stars and black-holes. Due to the extreme conditions that occur in supernovae, they are also the laboratories for extreme physics. The strong shock wave unleashed in a supernova heats up the environment to high temperatures. The resultant plasma produces emission in radio and X-rays, providing the best evidence of prevailing conditions in the supernova. We observe this emission using sensitive telescopes around the world and use it to draw inferences about the fateful star to advance our knowledg about their evolution.

Our team uses radio, optical and X-ray observations to address some of the most fundamental questions that can be asked about supernovae: What are the progenitors that give rise to the rich diversity among supernovae? How do the stars shape their environment leading up to the supernovae? Do black-holes drive energetic supernovae? In this project, depending on the student's inclination he/she will be involved in either observational or theoretical aspects of investigating supernovae.

ADVISOR: Dr. Ralph Kraft (HEA Division, CfA) 
CO-ADVISORS/MENTORS: Dr. Christine Jones (HEA Division, CfA)

PROJECT TITLE: Determining the Emission Mechanisms of the Extended Radio and X-ray Emission in the Galaxy NGC1052

Abstract: 
The elliptical galaxy NGC1052 has a very bright X-ray nucleus as well as extended X-ray and radio emission. Kadler et al. (2004) analyzed a short (2 ks) Chandra observation. In this project we will analyze a long 60 ks Chandra observation, in addition to two shorter Chandra observations, as well as 5 XMM-Newton observations, Suzaku and ROSAT (HRI and PSPC) observations. In the radio, there are both VLBI and VLA observations. Finally there also are HST observations of NGC1052 (von Dokkum et al 1995). Although much of the extended X-ray emission corresponds to radio features, the deep Chandra observations suggest there is more extended X-ray emission on the scale of a group of galaxies. This project will determine the X-ray luminosities and spectra of the various small scale X-ray components and compare these with radio emission to determine the primary emission mechanisms. We will also determine the gas properties of the more extended X-ray group emission, in particular if there is sufficient cooling at the center to feed the nuclear emission as well as the effects of the gas on the X-ray emission from the extended radio arms.

ADVISOR: Dr. Alicia Soderberg (TA Division) 
CO-ADVISOR/MENTOR: Dr. Jerod Parrent (TA Division)

PROJECT TITLE: Supernova Forensics: A Stellar Investigation from Cradle to Grave and Beyond

Abstract: 
The study of supernovae explosions has long focused on the strong radioactively-powered optical signal that dominates the bolometric luminosity in the weeks following one of these monster explosions. However, some of the most profound advances in our understanding of supernovae and their progenitor systems has been revealed through synergistic observations at other wavelengths including X-ray, gamma-ray, and the radio/mm-bands. In parallel with these observational efforts, theoretical modeling of the final evolutionary stages of stars has shed light on the final decades in a star's life. We propose a CfA REU student project designed to tackle the outstanding questions on one recent SN explosion from 2014 by combining data (already in hand) with MESA modeling of the putative progenitor star Through this project we aim to extract the physics of the explosion, properties of the environment and history of the progenitor star/system.

ADVISOR: Dr. Georgiana Ogrean (HEA Division) 
CO-ADVISOR/MENTOR: Dr. Paul Nulsen (HEA Division)

PROJECT TITLE: Systematic Uncertainties in Characterizing the Outskirts of Galaxy Clusters

Abstract: 
Galaxy clusters are the most massive gravitationally-bound structures in the universe. In clusters, the space between galaxies is permeated by diffuse, hot plasma called the "intercluster medium", which radiates via thermal bremsstrahllung at X-ray wavelengths. Clusters grow hierarchically by mergers with other clusters and by accretion of gas, and the footprints of this growth process are recorded in the outskirts of galaxy clusters. However, because the surface brightness is very low in the outskirts, X-ray studies of the outer regions of galaxy clusters are challenging. Spectra of cluster outskirts have a low number of source counts relative to background counts, which makes it crucial to correctly characterize the systematic errors associated with the spectral modeling.

Significant systematic uncertainties often make spectral analyses of galaxy cluster outskirts particularly controversial. While the limits to which XMM-Newton can characterize cluster outskirts have been investigated, a similar Chandra study has yet to be carried out.

In this project, the student will analyze archival Chandra observations of a large sample of galaxy clusters. The student will push Chandra's X-ray capabilities to the limit by measuring the density, temperature, pressure, and entropy profiles of the clusters as far out in the outskirts as possible. The student will evaluate the statistical and systematic errors associated with the measurements, and develop robust indicators to determine the limits at which systematic uncertainties bias spectral measurements performed with Chandra.

ADVISOR: Dr. Jayne Birkby (SSP Division)

PROJECT TITLE: Exoplanet Light Curve Studies

Abstract: 
Project will study the geometry of a hot Jupiter orbital system, calculate transit probabilities and the nature of any transit light curve. The student will test algorithms to examine the RV times series of a known transiting planet, possibly making observations with robotic telescopes to obtain new data and measure the planet's radius.

ADVISOR: Dr. Matt Ashby (OIR Division) 
CO-ADVISOR/MENTOR: (Dr. Howard Smith (OIR Division)

PROJECT TITLE: Luminous Merging Galaxies

Abstract: 
Project would be to reduce and help analyze all the Herschel SPIRE (250 micron - 650 micron) Fourier Transform spectra of all (about 40) the luminous merging galaxies in our program. We have another student working on the Herschel PACS spectra of these objects, and between the two of them, we'll have complete coverage. The science goal of this study is to understand how physical conditions in the galaxies vary as a function of the star formation rate.

ADVISOR: Dr. Viviana Guzman (SSP Division) 
CO-ADVISOR/MENTOR: Prof. Karin Oberg (SSP Division)

PROJECT TITLE: Spatial Distribution of Small Organics in Prestellar and Protostellar Cores

Abstract: 
Formaldehyde (H2CO) and methanol (CH3OH) are key species in the synthesis of more complex organic molecules, like amino acids and other prebiotic molecules. They also have great potential as molecular probes of a range of interstellar environments. It is therefore of great interest to understand how these molecules form. Theoretically, H2CO can form both in the gas-phase and on the surface of dust grains, while CH3OH is thought to form exclusively through grain surface chemistry. These different formation pathways should manifest themselves as different spatial distributions of H2CO and CH3OH line emission in star forming regions. Few detailed studies exist, however, that compare the spatial distributions of H2CO and CH3OH, and the main formation mechanism of H2CO in different interstellar environments is debated.

The goal of this project is to characterize the emission of H2CO and CH3OH, as well as other species, in two sources ( one prestellar and one protostellar) with known physical structures (density and temperature) to answer the following questions:

What are the spatial distributions of small organics such as H2CO and CH3OH in a prestellar and protostellar core, and how do they relate to the thermal and density structure and to each other?

Which organics have principally a grain chemistry origin? If a molecule can form both in the gas and on the grains, what regulates with pathway dominates?