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Physics Department

Location: 180-204
Phone: (805) 756-2448
Fax: (805) 756-2435
Chair: Jennifer Klay

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Louise Edwards

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Louise Edwards

Associate Professor

Office: 180-619
Phone: 805-756-7674


  • Ph.D., Université Laval, 2007
  • M.Sc., Saint Mary's University, 2003
  • B.Sc., University of Victoria, 2001

Research Interests

  • Astronomy and Astrophysics
  • The formation and Evolution of Brightest Cluster Galaxies
  • Galaxies in Cluster Cores and in Filaments


Dr. Louise Edwards joined Cal Poly in August, 2016, having been a lecturer in the Yale Astronomy department for 4 years prior. She was also an Assistant Professor of Physics at Mount Allison University, and held postdoctoral positions at the California Institute of Technology's Infrared Processing and Analysis Center and at Trent University. She received her PhD in Physics from Laval University in Quebec, Canada in 2007. Optical and infrared spectroscopy, along with photometric data from X-ray, through to Radio wavelengths allow Dr. Edwards to study the formation and evolution of galaxies. She is particularly interested in the cores and infall regions of rich galaxy clusters. In 2002, she was pictured on a Canadian stamp.


The Vera C. Rubin Observatory will see first light in 2023, observing the universe with the world’s largest digital camera. It will give unprecedented views of the universe with its 8.4 meter mirror and state of the art camera - producing catalogs of billions of galaxies across the universe. The Legacy Survey of Space and Time (LSST) from that observatory will generate the largest and most uniform sample to date of galaxy clusters. This is important for cosmological measurements and the study of the assembly of galaxies and their host clusters. Edwards is engaged with the Observatory in several ways: as a data preview (DP0) delegate, as a member of the commissioning team, and as PI of the NSF project: Establishing a CSU Community of Expert Rubin Observatory Users (2218943). Scientifically, she is examining the effect of the detector on the measurements of low surface brightness objects, and the effect of blending in cluster cores, as well as investigating galaxy populations in different environments within the preview dataset. 


Integral Field Spectroscopy allows for the detailed study of systems in both their spectral features, and morphological features. The image on the left is of Abell~85. The colour panel is a reconstructed image of the continuum emission. The BCG, some of its close companions, and the diffuse light in between can be observed. The instrument used is the SparsePak fiber bundle on the WIYN telescope in Arizona. Each fiber (represented by a blue circle) collects an optical spectrum. Galaxy kinematics and emission and absorption line properties can subsequently be studied in detail. Edwards and a team of undergraduate students at Yale have been conducting a IFS survey of nearby BCGs in X-ray bright clusters. The figure is from the theses of Hannah Alpert and Tara Abraham, and used in Edwards et al. 2016

More about the project can be found in this Research Note


Brightest Cluster Galaxies are today's most massive galaxies and are found in a particularly dense environment. Local clusters house these galaxies in their cores, at the gravitational potential of the system. These clusters contain massive amounts of hot, X-ray emitting plasma. This X-ray plasma contains a significant fraction of the cluster's baryons, and often times a peak in the X-ray surface brightness is observed. This relates to a dip in the central temperatures and the system is then referred as having a 'cool core'. When BCGs in cool core clusters are found to be coincident with the X-ray centroid, these large, red, elliptical galaxies ("red and dead") often show bright optical emission lines. Some of the questions I am trying to answer are: What is the origin of this emission, and how is it related to the X-ray emitting gas? When did these massive galaxies produce the bulk of their stars? And, how important are major and minor mergers to the evolution of these galaxies? The figure shows a large galaxy at the center of a rich cluster (z~0.25). The data from the Canada-France-Hawaii Telescope's legacy survey. The figure was generated using Stephen Gwyn's graphical search tool.


The Coma Cluster, having a redshift of about 0.023, is our nearest rich regular galaxy cluster. As such, it allows for a level of detailed study currently unavailable for more distant clusters. The figure to the left shows the spatial distribution of star formation in the cluster core, out to the infall regions. The position of each of the spectroscopically confirmed infrared-emitting members on the sky is shown. After compiling up to 15 photometric bands, SED fitting allows us to estimate the galaxy colors, masses, and star formation rates. Red points are passive galaxies, black are low specific star formers, blue are normal star forming, and cyan are starburst. Before looking into possible effects of environment, it is important to identify the galaxies based on mass, as there is a strong correlation between star formation activity and galaxy mass. The dwarf galaxies are shown as large points, and galaxies with masses greater than a billion solar masses are smaller points. Seyfert galaxies are shown as black triangles. The gray circle highlights the core region of the cluster, the black rectangle marks the field of view of the Spitzer Space Telescope observations. Contours show the galaxy density, i.e., the number of red-sequence galaxies per square degree. As can be seen, the core has a dearth of starburst galaxies. The figure is from Edwards & Fadda, 2011.

On the largest scales, cosmological simulations predict the structure of the universe consists of galaxies grouped in clusters, separated by voids, and connected by filaments. Observationally, determining the properties of these filament galaxies is challenging, as it requires deep imaging of vast fields, and extensive spectroscopic followup to remove foreground and background galaxies. But this is possible with today's instrumentation. What happens when galaxies fall into clusters via filaments? What is the role of pre-processing in filaments? What is the baryon content of the WHIM (warm hot intergalactic medium) and how can we use filament galaxies to measure this? This figure is based on data from Spitzer Space Telescope observations of Abell 1763 and follow up observations from Palomar, WIYN, and the Very Large Array. It illustrates the bending of radio lobes as a host galaxy travels through the hot gas of a cluster filament.

Peer-Reviewed Publications

  1. 2021/06 Efficient Detection of Emission-Line Galaxies in the CI0016+1609 and MACSJ1621.4+3810 Supercluster Filaments Using SITELLE 
  2. 2020/01 Clocking the formation of today's largest galaxies: wide field integral spectroscopy of brightest cluster galaxies and their surroundings
  3. 2018/12 The Megaparsec-scale Gas-sloshing Spiral in the Remnant Cool Core Cluster Abell 1763
  4. 2018/09 A Galaxy-scale Fountain of Cold Molecular Gas Pumped by a Black Hole
  5. 2016/09 Stellar populations of BCGs, close companions and intracluster light in Abell 85, Abell 2457 and IIZw108
  6. 2016/06 Cold, clumpy accretion onto an active supermassive black hole
  7. 2015/03 The Spitzer Archival Far-Infrared Extragalactic Survey
  8. 2012/09 Close companions to brightest cluster galaxies: support for minor mergers and downsizing
  9. 2012/06 Erratum: "A Multi-wavelength Analysis of Spitzer Selected Coma Cluster Galaxies: Star Formation Rates and Masses" (2011, AJ, 142, 148)
  10. 2011/11 A Multi-wavelength Analysis of Spitzer Selected Coma Cluster Galaxies: Star Formation Rates and Masses
  11. 2011/08 Spitzer observations of Abell 1763. III. The infrared luminosity function in different supercluster environments
  12. 2011/04 Subduction zone Hf-anomalies: Mantle messenger, melting artefact or crustal process?
  13. 2010/12 The First Bent Double Lobe Radio Source in a Known Cluster Filament: Constraints on the Intrafilament Medium
  14. 2010/12 Spitzer Observations of A1763. II. Constraining the Nature of Activity in the Cluster-feeding Filament with VLA and XMM-Newton Data
  15. 2010/02 Spitzer Observations of Abell 1763. I. Infrared and Optical Photometry
  16. 2009/07 The diverse nature of optical emission lines in brightest cluster galaxies: IFU observations of the central kiloparsec
  17. 2008/06 Structure, stratigraphy, and origin of Husband Hill, Columbia Hills, Gusev Crater, Mars
  18. 2007/07 Line emission in the brightest cluster galaxies of the NOAO Fundamental Plane and Sloan Digital Sky Surveys
  19. 2000/03 Galaxy Population Properties in the Rich Clusters MS 0839.8+2938, MS 1224.7+2007, and MS 1231.3+1542


Louise is passionate about Astronomy education and outreach. She was a member of the Canadian Astronomical Society's (CASCA) Education and Outreach committee for several years, has taught Astronomy, Math, and Physics courses at Cal Poly, Yale, Saint Mary's University, The University of Victoria, and the University of Southern California. She routinely presents her own public lectures in schools, colleges and community centers, and enjoys mentoring undergraduates in research. She was inaugural chair of the Hoffleit Fellowship program for undergraduate research in Astronomy at Yale, which brings students of any nationality to campus to work with research faculty. She co-chairs the Granville Institute hosted by Meg Urry at the Yale Astronomy. Currently she is a CASCA Westar Lecturer.

Courses taught:

  • Astr 101, Introduction to the Solar System, Spring 2016, Fall 2016, Spring 2017-2019
  • Astr 102, Introduction to Stars and Galaxies, Fall 2016 & Virtual Spring 2020, Virtual Summer 2020
  • Astr 200, Special Problems for Undergraduates
  • Astr 302, Stars and Galaxies, Spring 2019 & Virtual Spring 2020
  • Astr 400, Special Problems for Advanced Undergraduates
  • Astr 444, Observational Astronomy, Virtual Fall 2020
  • Phys 121, College Physics I, Winter 2018
  • Phys 122, College Physics II, Fall 2018, Winter 2019. Lab Winter 2019
  • Phys 142, Physics Studio, Fall 2022 and Spring 2023
  • Phys 461, Senior Project I
  • Phys 462, Senior Project II

Courses Taught before Cal Poly:

  • Astronomy 040 - Expanding Ideas of Time and Space (Yale)
  • Astronomy 110 - Planets and Stars (Yale)
  • Astronomy 155 - Intro to Astronomical Observing (Yale)
  • Astronomy 160 - Frontiers and Controversies (flipped in 2016) (Yale)
  • Astronomy 170 - Introduction to Cosmology (Yale)
  • Astronomy 220 - Galaxies and Cosmology (Yale)
  • Physics 1021 – Introduction to Stars and Planets  (Mount Allison)
  • Physics 1031 – Introduction to Stars and Galaxies (Mount Allison)
  • Physics 3021 – Life in the Universe (Mount Allison)
  • Physics 3811 – Modern Physics (Mount Allison)
  • Astronomy 420 – Galaxies and Cosmology (University of Southern California)
  • Physics 150 – Introduction to Astronomy (Trent University)

Student Researchers

  • Geetika Gopidas – Spring 2023 – Astro 200
  • Ricardo Pedrayes – Winter 2023 – Astro 200
  • Giselle Martinez – Winter 2023 – Spring 2023 - Rubin RUI
  • Joseph Perez – Fall 2022 – Spring 2023 PAARE
  • Max Allred – Improving Sparsepak Spectral Analysis - Fall 2022 (Physics 400)
  • Luisa Gonzalez – Galaxy properties and Color-Color diagrams - Summer 2022 PAARE
  • Vicente Puga (SP) – Using Matplotlib vs. Bokeh for Color-Mag diagrams - Summer 2022 PAARE
  • Melina Sarai Ruano – Galaxy properties at different scales – Spring 2022 – Summer 2022 PAARE
  • Adriana Gavidia (SP) – SDSS MaNGA galaxies in the X-Ray – Winter 2022/Spring 2022
  • Adam Looper (SP) – Investigating Star Clusters in the HST MAST database – Winter 2022/Spring 2022
  • Denvir Higgins (SP) - Weighing the Giants + BCGs with Rubin Obs. – Fall 2021-Winter 2022 & Fall 2022- Spring 2023 on PAARE
  • Samantha Allen - NSF BCG IR derived masses - Summer 2021
  • R.J.Chen - SDSS Manga Galaxies, companion colors - Summer 2021 (Aerospace Engineering)
  • Angela Chawla – Visualizing Large Galaxies - Fall 2020-W21 (Design Major)
  • Christopher Volek - Companions around 23 SparsePak BCGs – Summer 2020
  • Joey Sky - Companions around MANGA BCGs – Summer 2020
  • Kailei Gallup - Weighing the Giants – NIR Imaging of SparsePak cluster BCGs – Spring-Summer 2020
  • Chao Chen – Companions around SparsePak BCGs – Spring 2020
  • Kevin Hamel - BCGs with SDSS MANGA – Fall 2019-Summer 2020
  • Shubham Sengar - Weighing the Giants – NIR Imaging of SparsePak cluster BCGs – Spring 2019
  • *Kinsey Alexander - Weighing the Giants – NIR Imaging of SparsePak cluster BCGs – Spring 2019-Summer 2020
  • +*Kevin Zhang (SP) - The CL0016 supercluster, searching for starbursts - Spring 2019/Winter-Spring 2020. Companions around 23 SparsePak BCGs – Summer 2019/Summer 2020
  • +*Jaqueline Fraga – The CL0016 supercluster, searching for starbursts – Spring-Summer 2019
  • +*Jonathan Hernandez – BCGs and Companions with SDSS MANGA - Winter/Spring 2019 - Summer 2020
  • Emily Lucas –Using Python to visualize the age profile of galaxies - Summer 2018
  • Sam Philliber –Modelling cD galaxy envelopes - Spring 2018
  • Esmeralda Orozco – Visualizing DAFT/FADA superclusters - Spring 2018
  • +*Priscilla West (SP) –Data reduction of SparsePak standard stars - Summer 2017 – Summer 2020
  • +*Matthew Salinas (SP) –Data reduction of SparsePak galaxies - Spring 2017 - Spring 2019
  • +*Steffanie Stanley –Data reduction of SparsePak galaxies - Spring 2017 - Summer 2018

Undergraduate Research and Senior Projects (before Cal Poly):

  • Stephanie Spear –Data reduction of Halpha imaging for IIZw054, U2627, A2671 - Summer 2016
  • Tsveta Ivanova – Learning to code using Beizer astro-GUIs - Summer 2016
  • Renita Heng –Mapping Star formation with Halpha imaging in A262 - Senior Thesis 2015-2016
  • Peter Tang - Data reduction of Halpha imaging for A262 - Summer 2015
  • *Isabella Trierweiler – Stellar populations of BCGs and Intracluster Light - Summer 2015
  • *Leah Fulmer - The Virgo Cluster: SED fitting - Summer 2015
  • *Victoria Beizer – Development of GUI for SparsePak BCG visualization - Summer 2015
  • *Hannah Alpert - First results from a survey of local BCGs with the SparsePak imaging spectrograph: Abell 85, Abell 2457 and IIZw108 - Senior Thesis 2014-2015
  • Saisneha Koppaka – Analysis of SparsePak BCGs A1668, A2199,MKW3, Zw8338- Summer 2014
  • Anna O’Grady – Dragonfly Observations of Abell 569 - Summer 2014
  • Renita Heng –Halpha star formation rates of the BCG in A1204 and Ophiuchus- Summer 2014
  • *Tara Abraham – Visualizing the Stellar Populations of SparsePak BCGs- Senior thesis 2013-2014
  • Renita Heng – Morphological measurements of galaxies in A1763- Summer 2013
  • Eric Ho – 3D Visualization of Abell 1763 - Summer 2013
  • *Hannah Alpert – SparsePak Observations of Brightest Cluster Galaxies - Summer 2013
  • Vasilije Dobrosavljevic – Modeling Continuum emission from SparsePak BCGs - Summer 2013
  • Paola Oliva Alamirano and Scarleth Motino – Measured emission lines in BCGs: Masses, Ages and AGN status - MSc Thesis (National University of Honduras) 2010-2011

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