Jeff Cooke

Associate Professor   --   ARC Future Fellow
Centre for Astrophysics & Supercomputing
Swinburne University of Technology, PO Box 218, Mail number H29, Hawthorn, VIC 3122 Australia
office: +61 3 9214 5392   --   fax: +61 3 9214 8797   --   email: jcooke @

AR 315

Extragalactic Observational Astronomer

Main areas of research:
High redshift supernovae (z > 2)
Fast transients
  (including counterparts to fast radio bursts
   and gravitational waves)

High redshift galaxies and cosmic reionization
Interstellar and intergalactic gas

Press releases (example sites):
Host galaxy to a fast radio burst finally found!
The size of DLAs: Resolving a 40 year-old mystery
Extremely distant superluminous supernovae
The most distant supernovae
The massive merging galaxy LBG-2377

Some articles:
'The Conversation' on superluminous supernovae
'Nature' News & Views
'Nature SciLogs'

Below are some brief descriptions of a few of the projects that have been keeping me busy. The links are in various states of completion. Thank you for your patience as I (slowly) update each link.

  Detection of z > 2 supernovae
  Super-luminous and pair-instability supernovae
  Type Ia supernovae and cosmology
  "Orphan" supernovae and the first stars

  The Deeper, Wider, Faster campaign
  Fast radio bursts
  Electromagnetic counterparts to gravitational waves

  Lyman break galaxy interactions at z ~ 3
  Broadband selection of Lyman alpha emitters
  Spectral correlation functions and environment
  Bright galaxies at z ~ 4; the One-Degree Deep survey
  Lyman continuum galaxies and cosmic reionization
  Lyman alpha relationships with galaxy properties

  Mass of damped Lyman alpha systems (DLAs)
  Galaxies and MgII absorption-line systems
  Metal-rich gas near the epoch of reionization
  Damped Lyman_alpha_systems in galaxy sightlines

About a billion years after the Big Bang, the hydrogen in the Universe was ionized (changed from neutral gas to a plasma). It is believed that galaxies (the stars and supernovae in them) were responsible for the bulk of this change. Yet the number of galaxies found in distant surveys using standard selection methods and their individual contributions seem to fall short of doing the job.

Our new paper describes a technique we developed to measure the amount of escaping ionizing light from galaxies using the standard selection methods (termed Lyman break galaxies) and we also find that there are a significant number of galaxies that appear to have been missed in existing distant galaxy surveys. The missed galaxies, termed Lyman continuum galaxies, appear to have high fractions of escaping ionizing light and may have made a large contribution to the ionization of the Universe.

We recently confirmed the identification and redshift of a sample of Lyman continuum galaxies using the DEIMOS and MOSFIRE instruments on the Keck telescopes. We hope to use the LRIS instrument on Keck to directly measure the fraction of ionizing photons reaching Earth from these galaxies, thereby providing "smoking gun" evidence and a direct test of our predictions. In addition, we aim to use the WFC3 camera on the Hubble Space Telescope to acquire deep, high resolution imaging of these galaxies to determined the full extent of the ionizing photons and where they originate. This work is motivating new distant galaxy searches and opening up a new area of distant galaxy study.

Click here to access the ADS link displaying a list of articles describing my work.



Welcome to my office

The Australian Telescope Compact Array (ATCA) used to narrow down the location of the fast radio burst FRB 150418. The large 8.2m Subaru telescope was used to image the host galaxy of the fast radio burst. Deep spectroscopy from Keck and Subaru was used to identify the galaxy distance and propoerties. This is the first time a host galaxy to a fast radio burst was discovered and the first confirmation that fast radio bursts originate from great distances across the Universe. (credit: Alex Cherney)

Artist's impression of our technique used to detect and measure galaxy-sized gas clouds (called DLAs) in the early Universe. Light from extended background galaxies is used to illuminate the foreground gas clouds as the light journeys to Earth. The technique provides a 100 million-fold increase in the measurement of DLA sizes as opposed to the typical method using quasars. (credit: Adrian Malec and Marie Martig, Swinburne University)

Simulation of a superluminous supernova and its host galaxy in the chaotic formative environment at high redshift. All supernovae known in the early Universe (with lookback times more than 10 billion years, or redshifts greater than 2) have been discovered by our group. (credit: Marie Martig and Adrian Malec, Swinburne University)

The search for very distant (z ~ 2) supernovae in the Deep component of the Canada-France-Hawaii Telescope Legacy Survey has detected more than 30 candidate events and has used the Keck telescopes to spectroscopically confirm 12.

The images to the right illustrate the first step in finding these distant objects. Each frame shows a tiny section of one of the very large (one-square-degree) images centered on a distant galaxy that hosted a supernova.

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Each frame consists of an entire year's worth of images stacked together to better reveal these faint objects.
Below the three images is the 2004 image with the constant light from the galaxies subtracted away, revealing the supernova.

The 12 supernovae lay between z = 2 - 4 (thus, they occurred 10-12 billion years ago). Such detections are crucial in understanding early stellar and galaxy formation processes, the chemical enrichment history of the Universe, and exploring new types of supernovae.
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The Hubble Space Telescope

Physics 7D  
  Physics 20A
Curriculum Vitae
  Astro Grad Seminar
  Caltech Astronomy
UC Irvine
UC San Diego
W. M. Keck Observatory  
  NAOJ Subaru Observatory