The Canadian Galactic Plane Survey Mapping the Ecology Of the Milky Way Galaxy

A Universe of Stars? A Universe of Hydrogen gas

Understanding our Origins

The Evolution of Matter The “ecosystem” of galaxies

The Milky Way Galaxy is the only galaxy close enough to see the details of the Galactic “Ecosystem”. Challenges The Galaxy is very big. Because we are inside it, it completely encircles the earth. –A large area of sky must be observed. The Galaxy is a 3-dimensional object. –Must untangle the third dimension High Angular resolution is need to see the details in the context of the larger picture –A very large data base A large range of wavelengths must be covered to see all major components of the ISM –Several telescopes will be required.

Milky Way in Optical Light ( mm) Stars obscured by dust

Milky Way in Far-infrared Light ( mm) Old red stars with little obscuration

Milky Way at Sub-millimetre ( =0.240 mm ) Dust now seen as an emitter

Milky Way at Radio (21 cm) Atomic hydrogen gas (the basic stuff of the Universe)

The Milky Way at Radio (74 cm) Ionized gas and magnetic fields

The Canadian Galactic Plane Consortium Canadian Universities University of Calgary University of Alberta University of British Columbia University of Toronto University of Montreal University of Waterloo Queen’s University Université Laval National Research Council of Canada Dominion Radio Astrophysical Observatory Canadian Astronomical Data Centre International Organizations California Institute of Technology University of California, Berkeley University of Massachusetts University of New Mexico Space Telescope Science Institute Cambridge University Hamburger Sternwarte

Objectives of the CGPS Science Goals: How does the interstellar medium evolve? Explore the evolutionary relationship between the phases and states of the interstellar medium. How due galaxies convert diffuse primordial hydrogen to stars and the building blocks of life? What energizes and shapes the medium? Characterize the energy sources and modes of energy transport Is the Milky Way a closed system? Explore the vertical structure out of the disk. Is there mass and energy exchange between the disk and extragalactic space? Observing Goals: Create a high-resolution, 3-dimensional map of the interstellar medium of the Milky Way Construct a Galactic Plane Survey Data base of the distribution of major constituents of the interstellar medium.

The CGPS Data Base All images at 1 arcminute resolution

Where is the CGPS? Image compliments of Alan Dyer

The Dominion Radio Astrophysical Observatory

Milky Way at Radio (21 cm) Atomic hydrogen gas (the basic stuff of the Universe)

Atomic Hydrogen Image from a Single Antenna Radio Telescope 25-m Radio Telescope, Dwingeloo Netherlands Foundation for Radio Astronomy

Atomic Hydrogen Image from a Radio Interferometer 7-element Interferometer, Penticton Dominion Radio Astrophysical Observatory equivalent diameter equals 600m

Slicing up the Milky Way Galaxy Sun Galactic Centre Velocity changes systematically with distance along the line of sight.

The Doppler Shift Calgary City Police Officer Speeding Vehicle

Atomic hydrogen data “cube”

A top-down view of the hydrogen cube The Perseus spiral arm The Local spiral arm Outer spiral arm

A Walk Through the Galaxy

Optical Image Stars and Ionized gas (Thanks to Alan Dyer) Radio 21cm image Neutral Hydrogen gas (Perseus Spiral Arm)

Optical Image Stars and Ionized gas Far-Infrared Image Dust Particles

Optical Image Stars and Ionized gas Radio 74 cm image Ionized Gas

Optical Image Stars and Ionized gas Composite Image Hydrogen Gas Dust Ionized Gas

A 2000 Light-year section of the Perseus Arm.

Cold Hydrogen Clouds Clouds of very cold, dense hydrogen are seen silhouetted against a bright hydrogen gas. Where did these clouds come from? Temperature < 50 K (-220 C)

Are they related to molecular clouds? In some cases CO molecules are found. But in most cases there is no association.

A wider view of Cold HI and Molecular Clouds

Cold hydrogen in velocity space

Cold Hydrogen from a Spiral Shock Wave

Evidence of Large Scale Shocks A “spur” of dust and gas emerging from the galactic plane. All components of the interstellar medium merge in this spur. What caused it?

A Chimney to the Galactic halo The chimney is blown out by a cluster of massive hot stars at the bottom Intense ultra-violet radiation “leaks” out of the galaxy

Atomic Hydrogen Mushroom Cloud

Only a very small fraction of the Galaxy has been surveyed so far. The missing link between diffuse hydrogen gas and molecular clouds Evidence of transfer (leakage) of radiation and matter to extragalactic space (chimney and mushroom cloud) Examples of large scale shocks that energize the matter between the stars. … In this small fraction we have found:

What about the rest of the Galaxy?

A Global Survey: CGPS, VGPS and SGPS

A Global Galactic Plane Survey Dominion Radio Astrophysical Observatory National Research Council of Canada Australia Telescope Compact Array Commonwealth Science and Industrial Research Organisation Very Large Array U.S. National Radio Astronomy Observatory