McGill.CA / Science / Department of Physics

Astrophysics

This is a fascinating time in astrophysics, with new observational capabilities offering us a more detailed view of the universe and its constituents than ever before. McGill's Astrophysics group works at the forefront of a wide variety of major astrophysical research areas, including neutron stars, pulsars, magnetars, pulsar wind nebulae, X-ray binaries, thermonuclear bursts, black holes, gamma ray bursts, active galactic nuclei, galaxy evolution, galaxy clusters, microwave background, cosmology and exoplanets.

Members of the astrophysics group are affiliated with the McGill Space Institute.

Neutron stars/Pulsars
(A. Cumming, V. Kaspi, R. Rutledge)

The existence of neutron stars was predicted in the 1930s, more than 30 years before the first discovery of radio pulses from pulsar PSR B1919+21, in 1967. In the past 40 years new telescopes, instruments and detection methods have resulted in the discovery of nearly 2000 neutron stars. They can be observed in many wavebands, notably radio, X-rays and gamma-rays and are grouped into various categories including pulsars, magnetars, radio rotating transients, X-ray dim isolated neutron stars, and neutron star X-ray binaries.

[pulsar]
PSR J0737-3039A/B »
Artist's conception of the double radio pulsar PSR J0737-3039A/B.
Credit: McGill University, Office of Vice-Principal (Research and International Relations)
Animation by Daniel Cantin, DarwinDimensions
The McGill Neutron Star and Pulsar group studies a diverse range of subjects in observational pulsar physics, using data from many of the world's most powerful observatories and satellites, including Chandra, XMM-Newton, Swift and soon, NuSTAR. We study interesting individual systems such as double pulsars, magnetars, low mass X-ray binaries and supernova remnants, as well as the distant and enigmatic gamma-ray bursts. We are also involved in large-scale surveys to discover new pulsars using large radio telescopes, including Arecibo and the Green Bank Telescope.

The McGill Neutron Star theorists are interested in the fundamental structure of neutron stars. We investigate the origin and evolution of their spin and magnetism, their interior structure, and the properties of neutron star binary systems.

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Galaxies & Cosmology
(M. Dobbs, D. Haggard, T. Webb)

[Deep Field]
Deep Field »
Hubble Deep Field.
Credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team
The Galaxies and Cosmology group at McGill includes observers, theorists and experimentalists studying the evolution of galaxies, supermassive black holes, clusters of galaxies, and the cosmic microwave background to understand the processes by which our Universe formed and evolved.

McGill is involved in numerous CMB experiments. One of these experiments is the South Pole Telescope (SPT), which is surveying the CMB for “shadows” of galaxy clusters: the largest gravitationally bound objects in the universe. The detection and characterization of these galaxy clusters allows us to probe structure formation, cosmological parameters and the equation of state of dark energy: an enigmatic substance driving the accelerated expansion of our universe.

Our observational cosmologists use world-class telescopes such as Gemini, the Spitzer Space Telescope, the Chandra X-ray Observatory and the Very Large Array to look back in time and investigate the detailed physics of galaxy and black hole evolution. We are interested in the processes which build the stellar mass of galaxies, feed the supermassive black-holes at their centers, and group them into the structures and shapes we see around us today.

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Experimental Astrophysics
(M. Dobbs, D. Hanna, K. Ragan)

[electronics]
Frequency multiplexer »
Digital frequency multiplexing board, developed at McGill for reading out large arrays of low temperature bolometric detectors.
The experimental astrophysicists at McGill contribute to the building of observational facilities to explore various energy bands in astrophysics. Our high-energy research is carried out with the VERITAS observatory in Arizona which is sensitive to gamma rays with energies from 100 GeV to over 30 TeV.

We also have an active cosmology instrumentation lab that has developed important components for cosmic microwave background detectors such as the South Pole Telescope and the balloon-borne polarimeter, EBEX. Key components of the proposed CHIME hydrogen mapping experiment will be developed at McGill.

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Exoplanets
(N. Cowan, A. Cumming, E. Lee)

[exoplanet]
Exoplanet »
An artist's impression of a possible exoplanet.
Credit: PPARC

The number of detected exoplanets now count well over thousands, affording us a birds-eye view of planet demographics in our Galaxy. These observations offer an opportunity to answer basic questions about where, when, and how planets form, the three-way interaction between stars, disks, and planets, as well as the physical processes occurring in exoplanet interiors and atmospheres.

The exoplanet group at McGill investigates a wide range of research—both observations and theory—including the formation and evolution of planetary interiors and atmospheres, planetary dynamics, star-disk-planet interactions, observations of exoplanet surfaces and atmospheres, and characterizations of planetary habitability. Our research tools range from simple pen & paper, to supercomputing clusters, to telescopes both on the ground and in space.

McGill researchers working in exoplanets are members of the Institute for Research on Exoplanets (iREx).

Nuclear Astrophysics
(A. Cumming, R. Rutledge)

[neutron star accreation]
Thermonuclear flash »
Thermonuclear flash on an accreting neutron star
Credit: NASA Goddard Space Flight Center
Nuclear astrophysics is at the intersection of astrophysics and nuclear physics. It concerns the study of the origin of the chemical elements in stars and supernovae, explosive events such as supernovae, classical novae, and X-ray bursts, and the properties of matter at high densities as found in the interiors of neutron stars. Nuclear astrophysics research at McGill is focussed on developing connections between nuclear properties and astrophysical observations through the study of neutron stars.

One focus of research at McGill is modelling the transient behavior of accreting neutron stars on timescales of seconds to years. This requires knowing the properties of nuclei across the mass table, from the most proton rich radioactive nuclei to the most neutron rich. Thermonuclear flashes from unstable hydrogen and helium burning on the surface of an accreting neutron star involve the rp-process, a rapid proton capture process that produces heavy nuclei near the proton drip line. Deeper inside the neutron star crust, nuclei at and beyond neutron drip are present, and determine the transport properties of the crust that can be probed with observations of crust cooling on timescales of months to years.

Another focus is measuring the radius of neutron stars. Neutron star radius and mass measurements give powerful constraints on the properties of the bulk nuclear matter that should exist in the cores of neutron stars. At McGill, we use observations of the thermal emission from neutron stars to measure the neutron star radius and constrain the equation of state of dense matter.

McGill is an Associate Member of the Joint Institute for Nuclear Astrophysics - Centre for Evolution of the Elements (JINA/CEE).

Black Holes
(D. Haggard)

[black hole]
First image of a black hole»
Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity.
Credit: Event Horizon Telescope Collaboration
A supermassive black hole (SMBH) lurks at the heart of every massive galaxy, including our Milky Way. These monsters, agglomerations of mass so dense that even light cannot escape their gravitational pull, have a profound impact on the formation and structure of their host galaxies, despite being packed into structures smaller than our own Solar System. SMBHs grow in many ways, but most dramatically via gas and dust inflowing through a flat, variable accretion disk — during growth spurts, accreting SMBHs are called quasars or active galactic nuclei (AGN).

McGill scientists pursue studies of massive black holes in AGN , as well as stellar-mass black holes in binaries, detected via high energy and gravitational wave emission. Black hole accretion disks, and sometimes an associated jet or wind, are some of the brightest objects in the Universe and, since every part of this dynamic structure varies with time, strategic monitoring of a large number of black holes can pave the way to new insight. Our teams pursue multi-wavelength and multi-messenger studies of black holes with a wide range of elite telescopes, e.g., the Event Horizon Telescope, the Canada France Hawaii Telescope, and the Chandra X-ray Observatory , and in coordination with gravitational wave experiments like LIGO-Virgo and the upcoming LISA Mission.
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