Thesis Work
If you are interested, here is a copy of the presentation I gave for my thesis defense in April 2013.
Star Formation in Galaxy Outskirts
The outer disk spiral arms of M81, caused by the interaction with M82 and NGC3077, are fertile grounds for exploring star formation in low density environments. The area is characterized by extended HI arms and filaments within which are found HII regions and dwarf galaxies, including Holmberg IX. Much attention has focused in past years on the evidence for star formation and on the properties of the stellar populations detected in these HI features, especially from recent GALEX and HST observations. I am currently studying the HII region population over a 1.5 degree field, derived from a Burrell Schmidt H-alpha composite supplemented with ARC 3.5-m telescope emission line images of both inner and outer disk HII regions. I am interested in the luminosities and morphologies of the HII regions and comparing the current massive star formation with the recent and past rates inferred from the stellar populations detected in the outer disk features. I am also looking at abundances for these star forming regions to help determine the origin of outer disk gas. Below you can find a link to my paper, finding a shallow metallicity gradient for the HII regions of M81.
Gas Accretion
I am a member of the HALOGAS collaboration.
The
Faint Stellar Streams and Low Surface Brightness Features Around Galaxies
Deep and widefield optical imaging is essential to understand the role of accretion and the source of accreting gas and new material in galaxies. I have imaged the HALOGAS Survey sample of galaxies in broadband and emission line filters with the Kitt Peak National Observatory's 4-meter telescope, in order to search for faint companions and stellar stream features around the galaxies. We are comparing these images with our very deep HI data to better understand the process of galaxy growth.
Neutral Hydrogen in the Local Group
In the summer of 2008, I worked for 6 weeks at the Australia Telescope National Facility in Sydney, Australia with Dr. Robert Braun, studying and comparing opaque HI clumps in M31, M33, and the Large Magellanic Cloud. These regions of localized opaque gas are interesting since they are not always well correlated with CO detections (which trace molecular gas), and initial inspections show that those without CO counterparts may be representative of early evolution toward giant molecular cloud formation.
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On the left is a log column density map of M31 assuming optically thin gas.
On the right is the same image corrected for opacity, for comparison.
High column density opaque gas can be seen in clumps peppering the disk
in the righthand image. (Image courtesy of Robert Braun.)
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Halo Gas Kinematics
I began my graduate studies at NMSU in Fall 2007, working with Dr. Rene Walterbos using multi-slit spectroscopic images to produce rotation curves for the diffuse gaseous halo of NGC891 and several other edgeon galaxies. The diffuse gas rotates more slowly than the cooler dense gas in the plane of the disk, and the underlying cause for this lag is not well understood. Below is an example spectrum of the halo gas taken using the multi-slit technique. Using spectra like this one, we can derive the kinematics of the halo gas.
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A multi-slit spectrum of Halpha for the north end of NGC891 taken with
the 3.5-meter at APO using a 16-slit mask. The x-axis shows the distribution
of flux with wavelength, and the y-axis is position. The diffuse gas above
and below the disk of the edge-on
galaxy can be seen in white in the center running along the x-axis.
The brightest white
spots are due to foreground stars.
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Meetings/Publications
Paper:
An Oxygen Abundance Gradient into the Outer Disc of M81 [abstract]
-Monthly Notices of the Royal Astronomical Society, Volume 422, Issue 1, pages 401-419, May 2012
Conference Proceedings One-pager: Deep HI Observations of NGC 5055 from the HALOGAS Survey
- May 2012, Gas Flows in Galaxies 2012 STScI May Symposium, Baltimore, MD
15 minute talk:
- April 2012, Tully-Fisher at 35: Global Properties of HI in Galaxies Workshop, NRAO, Green Bank, WV
Informal Pizza Lunch Talk:
- March 26, 2012, NMSU Astronomy Department, Las Cruces, NM
Poster:
HI Streams and Spurs in HALOGAS Observations of NGC 5055
[abstract]
- January 2012, 219th Meeting of the American Astronomical Society, Austin, TX
Informal Pizza Lunch Talk:
- October 31, 2011, NMSU Astronomy Department, Las Cruces, NM
15 minute contributed talk:
- October 14, 2011, 27th Annual New Mexico Symposium, Socorro, NM
Poster:
The HALOGAS Project: HI Observations of NGC 5055 and NGC 4258
One slide discussion talk:
HALOGAS Observations of NGC5055
- June 2011, Gas in Galaxies: From Molecular Clouds to Cosmic Web, Kloster Seeon, Germany
10 minute talk:
- April 2011, New Mexico Space Grant Colloquium, NMSU, Las Cruces, NM
Poster:
The HALOGAS Project: HI Observations of NGC 5055
[abstract]
- January 2011, 217th Meeting of the American Astronomical Society, Seattle, WA
- March 2011, Graduate Research and Arts Symposium, NMSU, Las Cruces, NM
Poster:
HII Regions in the Outer Disk and Tidal Arms of M81
[abstract]
- January 2010, 215th Meeting of the American Astronomical Society, Washington D.C.
- January 2010, 25th Annual New Mexico Symposium, Socorro, NM
Poster:
Extraplanar Gas Extent of Edge-on Galaxies: A Comparison of the Galaxies NGC4244 and NGC891
- June 2009, Galaxy Metabolism, Sydney, Australia
Poster:
Interstellar Gas and Massive Stars in External Galaxies: Initial Results for the Galaxies M33 and NGC4517
- April 2009, Graduate Research and Arts Symposium, NMSU, Las Cruces, NM
Poster:
Multi-long-slit Spectroscopy for Kinematic Studies. I. Implementation and Demonstration
[Abstract]
Rene Walterbos, J. Choi, S. Cisneros,
- January 2008, 211th Meeting of the American Astronomical Society, Austin, TX
Poster:
Multi-long-slit Spectroscopy for Kinematic Studies. II. Initial Results for the Edge-On Galaxies
NGC891 and NGC4244 [Abstract]
Jiehae Choi, S. Cisneros, C. Wu,
- January 2008, 211th Meeting of the American Astronomical Society, Austin, TX
ADS author query for Maria T. Patterson
Curriculum Vitae
Here is a copy of my Academic CV.
NMSU Homepage
You can also visit Maria's NMSU Astronomy directory research page.
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