PROJECT TITLE:   X-ray Bright Optically Normal Galaxies (XBONGs) in the XBootes Field

	ADVISOR:   Dr. Steve Murray
        INTERN:    Michael Anderson, University of Michigan
        MENTORS:   Almus Kenter, Ryan Hickox, Christine Jones, Bill Forman
	

Advisor's project abstract:

The Nature of XBONGS

While X-ray surveys have shown that the X-ray background is due almost
entirely to emission from broad line AGN, X-ray observations have also
identified a class of galaxies which are X-ray bright (with typical
luminosities of 1042 ergs/sec and thus generally assumed to be
associated with accretion onto a supermassive black home), but whose
optical spectra do not show emission lines, as would be expected from
an AGN. The nature of these galaxies is presently unknown. One
suggestion is that these XBONGS (X-ray Bright Optically Normal
Galaxies) may be obscured, so that emission from their nuclei is not
seen optically. Another possibility is that the galaxies are so
bright, that the galaxy emission dominates the optical spectra.
XBONGS also have been suggested to be BL Lac-like systems. A fourth
suggestion is that these galaxies do not contain optically thick
accretion disks, but instead have an advection donimated (ADAF) or
radiatively inefficient accretion flow (RIAF).  So far the number of
XBONGS that have been identified and studied is relatively small
(∼30).

In the XBootes Chandra survey, we have ∼200 XBONG candidates, X-ray
luminous galaxies with absorption line optical spectra. With the large
Bootes spectroscopic galaxy survey, one can determine the environment
for each XBONG and compare their local galaxy density to that of broad
line AGN, as well as to normal galaxies with similar optical
magnitudes and colors.  With this large sample, one also can measure
the spatial correlation length and may also be able to measure the
luminosity function for XBONGS. A comparison of their environment and
X-ray properties (including spectra) to type 1 AGN and to normal
galaxies may determine the nature of these unusual galaxies.
    

PROJECT TITLE:   Star Formation in Bright-Rimmed Clouds

 
	ADVISOR: Dr. Lori Allen
        INTERN:  Sarah Ballard, University of California at Berkeley
        MENTOR:
	

Advisor's project abstract:

Star Formation in Bright-Rimmed Clouds

Bright-Rimmed Clouds (BRC) are relatively isolated molecular clouds near
hot young O stars.  They are recognized in the optical as small dark
clouds, often having a cometary morphology, with an ionization front  
(bright rim) facing the direction of the ionizing stars. Because of 
their isolated, compact structure, their proximity to young high mass 
stars, and the presence of an ionization front, bright-rimmed clouds
are excellent laboratories for studying triggered star formation.

One such sample of BRC are currently being studied in a Spitzer GTO
program. The sources were selected from the catalogs of Sugitani & Ogura
(Sugitani, Fukui, & Ogura, 1991; Sugitani & Ogura 1994),  who scoured
optical sky survey plates and compiled a list of small clouds bounded on
at least one side by a bright rim, and containing one or more IRAS  
sources having colors consistent with young stars.

To date, no complete census has been obtained of the young stars in
BRC, and their status as sites of triggered or sequential star formation
remains unproved. With the Spitzer Space Telescope, we now have the  
ability to detect all of the young stars in these clouds, and to 
determine whether they contain protostars (evidence of very recent star 
formation triggered by their neighboring OB associations), or only more
evolved T-Tauri stars (coeval with the OB associations).  The researcher 
who takes this project on will perform photometry on the Spitzer data
using a local photometry program written in IDL (author of the  
software, Dr. Rob Gutermuth, is here and will be available for 
consultation).  After a brief period of verifying the photometry results 
(and tuning the program as needed), the researcher will compile 
photometry on the entire sample and do statistical studies of the young
stellar content of these clouds.  These include the multiplicity of 
sources, evolutionary state of the young stars, the frequency of
protoplanetary  disks, the spatial distributions, etc.  It is  
anticipated that this work will form the basis for a paper suitable for 
publication in the Astrophysical or Astronomical Journal.
    

PROJECT TITLE:   Fabrication of Future X-ray Telescopes by Selective Deposition

 
	ADVISOR: Suzanne Romaine
        INTERN:  Amy Colon, Hunter College
        MENTOR:  Ricardo Bruni
	

Advisor's project abstract:

Mirror figuring using selective coating deposition 
        
We are currently involved in building a prototype optic 
for the Constellation-X Mission, the followup Mission to Chandra.
Looking to the future of high spatial resolution X-ray optics,
improving, or even meeting, the resolution of the Chandra telescope, 
especially under tight budget constraints of future missions,
presents us with serious technical challenges and will strain our 
imagination and creativity.
 
Along these lines, we have a program to investigate the figuring
of x-ray optics using fine control of the deposition of thin films
to correct the figure of the optic. The proposed project will involve
the student in a study of grazing incidence X-ray optics and will 
carry out a program of test coatings to understand and define 
the limits to which we can take advantage of this technology.
        
The proposed project will involve the student in the fabrication of
materials and coatings which is necessarily an interdisciplinary
experience.  Several areas including: physics, astronomy, optics,
materials science and engineering are applicable in this project.
    

PROJECT TITLE:  High Resolution Ultraviolet Spectroscopy of the X-ray Binary Cyg X-1

 
	ADVISOR: Saeqa Vrtilek
        INTERN:  Adrienne Hunacek, MIT
        MENTOR:  Joey Neilsen
	

Advisor's project abstract:

Doppler Tomography of X-ray Binaries

This project is to construct "images" of x-ray binaries using the
method of modulation tomography. The student will use existing data
from the ESO archives to study the geometry of accretion flow in
systems that contain neutron stars of black holes. The process is
similar to that used in medical tomography. The images reconstructed
via Doppler tomography provide unique and detailed insights into the
structure of the accretion flow around compact objects. This should
result in a short but interesting paper.
    

PROJECT TITLE:   Detecting AGN Through Variability in IRAC's Calibration Field

 
	ADVISOR: Dr. Joseph Hora
        INTERN:  Lauren Hund, Furman University
        MENTOR:  
	

Advisor's project abstract:

The Spitzer Space Telescope is the fourth and final great observatory and
has created entirely new opportunities to study and better understand
objects in the distant, early universe.  This is due to a combination of
Spitzer's unprecedented sensitivity in the mid-infrared (3-10 microns) and
its privileged position in a novel earth-trailing orbit, where the
celestial backgrounds are very low and even thermal emission from the earth
is minimized.

We are seeking a motivated student to work with existing Spitzer imaging
data of a unique field, the IRAC Calibration Field (IRAC-CF).  This
particularly infrared-dark region offers an extremely deep view of
extragalactic space, even by Spitzer standards.  It has been observed for
1-5 hours every 1-4 weeks with Spitzer's Infrared Array Camera (IRAC)
since December of 2003.  This accumulation of data is expected to continue
steadily for the remainder of the Spitzer mission, meaning that the
infrared sensitivity will eventually be the deepest in existence,
exceeding even the ultra-deep GOODS fields with four times the area.

One special attribute of this dataset is its temporal coverage -- since
the field is observed roughly once every month, it is possible to find and
characterize distant active nuclei (AGN, or supermassive black holes)  in
the infrared as they dim and brighten from month to month, and indeed
several already have been found.  These objects are also being observed
monthly from the ground via coordinated R-band imaging at the Palomar 60",
so as to correlate the infrared and visible-wavelength behavior of these
objects.  Other supporting observations with the other Spitzer instruments,
HST/ACS, and Akari are either approved or already completed.

This project is well-advanced, but needs some careful attention before it
can be brought to completion.  The student would be responsible for
verifying the existing detections of variable nuclei and for refining the
images to isolate even more variable objects.  The student will be taught
how to use MOPEX (the Spitzer data reduction software) to improve upon the
existing mosaics, and how to perform precise source photometry with
SExtractor.  The student would then manipulate the galaxy catalogs he/she
created to examine the trending behavior of these active nuclei.
    

PROJECT TITLE:   The Spitzer Interacting Galaxies Survey: IRAC Evaluations of Star Formation

 
	ADVISOR: Dr. Matthew Ashby
        INTERN:  Christopher Klein, Caltech
        MENTORS:  Dr. Andreas Zezas and Dr. Howard Smith
	

Advisor's project abstract:

 
The Spitzer Space Telescope is the fourth and final great observatory
and has created entirely new opportunities to study and better
understand fundamental aspects of star formation in galaxies.  This is
due to a combination of Spitzer's unprecedented sensitivity in the
mid-infrared (3-10 microns) and its privileged position in a novel
earth-trailing orbit, where the celestial backgrounds are very low and
even thermal emission from the earth is minimized.  New Spitzer
results are being published every day, and are having a significant
impact in many different fields.

We are midway through an approved Spitzer program to study whether and
how star formation and nuclear activity within galaxies are influenced
by major mergers, i.e., mergers between galaxies of comparable mass.
Star formation has long been thought to result from triggering
processes of various kinds, including supernovae shock waves and
galaxy collisions.  The student will have the opportunity to measure
the basic set of observable quantities (luminosities, star-formation
rates, morphologies) from newly-acquired Spitzer observations of
numerous galaxy-galaxy pairs in various stages of merging.
Specifically, we are seeking a motivated student to accomplish the
following:

1. Process the galaxy images to create optimal mosaics in all four
mid-infrared IRAC bands, using existing software with which our team
is very familiar.

2. Quantify the amount and spatial extent of star forming activity
in the sample galaxies, and search for trends with respect to
merger stage and galaxy type.  It is hoped that these data will allow us
to assess a newly-developed understanding of how galaxies evolve in 
the infrared.

3. Apply simple criteria to detect active nuclei in cores of the merging 
objects.

The work outlined is substantial, but it ought to be feasible within
the 10-week term of the REU appointment.  We have decided to form a
three-person team to advise the student.  Ashby will serve as team
leader and be responsible for the outcome of the REU project; Zezas
will serve as backup when Ashby is (briefly) on travel and will help
set the analysis strategies; Smith will help relate the results to the
nascent galaxy evolution theory.  If the student makes rapid progress,
he/she may have an opportunity to analyze complementary MIPS 24 micron
imaging observations as well, which will aid in the interpretation of
the IRAC mosaics.
    

PROJECT TITLE:   A Two-Fluid Plasma Shock Wave Model for the Strong Shock in Centaurus A

 
	ADVISOR: Dr. Paul Nulsen
        INTERN:  Robert Penna, University of Rochester
        MENTOR:  
	

Advisor's project abstract:

The Strong Shock in Centaurus A

Centaurus A (Cen A) is the nearest radio galaxy to us.  Its active
nucleus (black hole) pumps out energy in twin radio jets that interact
with the surrounding interstellar medium creating radio emitting lobes
of relativistic plasma.  Energy is being pumped into the southwestern
radio lobe fast enough to create a region of high pressure, that
expands explosively and drives a strong, Mach 8, shock into the
surrounding interstellar gas.  In X-ray observations with the Chandra
Satellite, the lobe appears as a cavity, surrounded by a region of
bright X-ray emission that comes from the heated and compressed,
shocked gas.

This is an example of a "collisionless" shock.  Shocks are regions of
rapid dissipation, where the kinetic energy of supersonic gas gets
converted rapidly into thermal energy.  Normally, this happens over
distances that are similar to the mean-free-path of gas particles.  In
the plasma around Cen A, the kinetic energy of the protons gets
converted into thermal energy much more quickly.  However, the
electrons still rely on the collisions to get their share of the
energy from the protons, and this takes much longer.  As a result, the
electrons heat up relatively slowly, over distances that are resolved
in the X-ray observations.

In a strong shock, like the one in Cen A, the final temperature of the
gas depends only on the density of the gas before the shock and its
pressure after the shock.  The gas inside the lobe is expected to have
the same pressure, but the density of the gas outside the lobe varies,
so we would expect the shocked gas to have different temperatures
around the lobe.  It is a puzzle that all the shocked gas seems to
have the same temperature.  One possible project is to make a model
for the collisionless shock around Cen A, to see if we can explain
this puzzle, along with other features of the shock.

    

PROJECT TITLE:   Recognizing Loops in the Solar Corona: A Diagnostic Tool for Magnetic Field Extrapolation Models

 
	ADVISOR: Dr. Vinay Kashyap, Dr. Ed DeLuca, and Mark Weber
        INTERN:  Julia Sandell, Columbia University
        MENTOR:  
	

Advisor's project abstract:

Finding Magnetic Loops on the Sun

The corona on the Sun is made up of very hot plasma (greater
than a million degrees) that is threaded and maintained by
a pervasive magnetic field.  It is believed that the corona
is heated to such high temperatures because of the energy
released when highly stressed magnetic fields reconnect and
relax to a lower potential configuration.  The three dimensional
structure of the magnetic fields is therefore of much interest.
There exist methods that extrapolate the 3D fields from
surface flux measurements, and the extrapolated field lines
are then validated by comparing with high-resolution EUV
images of the solar corona from TRACE.  We are now developing
a process by which this validation can be done automatically,
by comparing the field lines to morphologically identifiable
coronal loops.  The intern will take an active part in the
development of the morphological loop finding method using
TRACE data, and in adapting the magnetic field extrapolator
to work for future solar missions.
    

PROJECT TITLE:   Optical Counterparts to Supersoft X-ray Sources in the Nucleus of M31

 
	ADVISOR: Dr. Rosanne diStefano
        INTERN:  Sarah Scoles, Agnes Scott College
        MENTOR:  
	

Advisor's project abstract:

X-rays from Exotic New Sources

Soft X-ray sources have been studied for only about 15 years.
Some may be progenitors of Type Ia supernovae. Some may be
black holes. Others may be soft states of X-ray sources that 
can also exhibit hard states. We are conducting research along
several fronts to study soft X-ray sources in other galaxies.
Three projects are ideal for a summer intern. (The intern would 
choose the project.) One of these would be to conduct research
to follow up on clues that soft X-ray sources are more common
in the vicinity of supermassive black holes. Chandra data from the 
central regions of a set of nearby galaxies will be studied to
determine if there is a genuine excess of soft sources and to
quantify and understand the effect, if it is verified. It
has been postulated some of these stripped soft sources could 
be the stripped cores of giant stars that have been tidally 
disrupted by the supermassive black hole. The second project would be to
work with a rich archive of HST observations of the center of M31.
This work will explore the connections between X-ray sources and optical
emission in the vicinity of the black hole. Finally, we have a suite
of ongoing theoretical projects designed to understand the fundamental
natures of soft X-ray sources, particularly near galaxy centers.
    

PROJECT TITLE:   Recovering Long-Term Lightcurves from the Harvard Plates: A Search for Eclipsing Binaries in M44

 
	ADVISOR: Dr. Josh Grindlay
        INTERN:  Michael Shaw, MIT
        MENTOR:  Bob Simcoe, Silas Laycock 
	

Advisor's project abstract:

Initializing the DASCH -- out to M44 and beyond

The world's fastest (by 200x) astronomical plate scanner has been just
completed and commissioning runs will begin with this project to
digitize a century of Harvard plates on the galactic cluster M44. This
inauguration of the Digital Access to a Sky Century from Harvard
(DASCH) project will digitize (at only 20sec each) at least ∼100
plates (typically 8 x 10in) containing historical (c. 1890 - 1990)
images of the open cluster M44 (the Beehive Cluster). Using the
well-calibrated stars in this cluster, this will further develop
astronomical photometry analysis routines for the digitized plate
images and allow a search for eclipsing binaries, and other variables,
within or beyond the cluster. New binaries may be discovered within
the cluster (since at least one was found from test scans of the
cluster with a pre-DASCH commercial scanner) and can be follow up with
archival ROSAT and other data to derive system properties. Since M44
is nearly on the ecliptic, a search will be conducted for asteroids or
other high proper motion objects. The high galactic latitude (33deg)
of the field and large number of mag. 14-15 galaxies included on each
plate will permit a search for historical supernovae.
    

1)   Michael Anderson
     University of Michigan

Abstract:
X-ray Bright Optically Normal Galaxies (XBONGs) in the XBootes Field

-------   Text of final project abstract is not available.
-------   Advisor:  Dr. Steve Murray

To top of page...

Abstract:
   Star Formation in Bright-Rimmed Clouds

-------   Text of final project abstract is not available.
-------   Advisor:  Dr. Lori Allen

To top of page...

To top of page...

To top of page...

Abstract:
 Detecting AGN Through Variability in IRAC's Calibration Field

-------   Text of final project abstract is not available.
-------   Advisor:  Dr. Joseph Hora

To top of page...

 The Spitzer Interacting Galaxies Survey: IRAC Evaluations of Star Formation

-------   Text of final project abstract is not available.
-------   Advisor:   Dr. Matthew Ashby