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Steve Strom – The Galaxy Evolution Years (1976-1984)
Pioneered instrumental and observing techniques to measure the right kind of stuff for galaxies.
The Universe in 1976
Photographic detectors predominate Dark Matter wasn’t an issue The hierarchical clustering pattern for
galaxies was not well known yet There were no large low surface brightness
galaxies Density wave theory was popular Early galaxies lived in clusters of galaxies
Properties of Galaxies
Shape, structure (surface photometry), morphology Stellar populations – young (optical), old (infrared) Dynamics – rotation curves Bulge/Halo properties Abundance gradients (as related to density waves) Environment/interaction index
Strom’s Legacy
Was really the first to systematically probe and integrate the various measurable properties of galaxies so that some coherent theory might arise
His approach influenced other “young” researchers at the time to enjoy the thrills of constant data overload
Legacy ChronologyLegacy Chronology
Initial focus is on Abundance Initial focus is on Abundance GradientsGradients
Next: Integration of Next: Integration of WavelengthsWavelengths
This approach would prove to be a This approach would prove to be a hallmark of Strom’s work and hallmark of Strom’s work and remember, detectors sucked back remember, detectors sucked back then.then.
Next: Integration of Dynamics and Environmental Influences To help understand variation in spiral arm
strength/definition and prevelance of smooth arm spirals in clusters
Next: Size MattersNext: Size Matters
A prophetic statement: “… A prophetic statement: “… the true sizes the true sizes of spiral galaxies must be considerably of spiral galaxies must be considerably larger than currently believed”larger than currently believed”
And then its time to move on
To the intense study of bi-polar jets and other micro physics in star forming regions.
Perhaps its coincidental, but one can’t help wonder if the first author of this last paper helped drive this change in direction
TodayToday
Massive LSB galaxies are known to exist Massive LSB galaxies are known to exist (but, alas, they are not very pretty and are (but, alas, they are not very pretty and are mostly just noise)mostly just noise)
TodayToday
Galaxies are clustered in far more Galaxies are clustered in far more complex ways than anyone could ever complex ways than anyone could ever have imagined.have imagined.
Encounters/environmental influence is Encounters/environmental influence is likely therefore largerlikely therefore larger
But what do we know But what do we know Today?Today? Why is the Baryonic mass fraction of Why is the Baryonic mass fraction of
galaxies a constant?galaxies a constant? Why don’t galaxies have hard edges if Why don’t galaxies have hard edges if
star formation is density driven?star formation is density driven? Why is the Galactic Halo still being Why is the Galactic Halo still being
formed from stars streaming in?formed from stars streaming in? What determines how many stars in the What determines how many stars in the
dark matter dominated gravitational dark matter dominated gravitational potential form in the first generation.potential form in the first generation.
How does galaxy assembly really work?How does galaxy assembly really work?
SummarySummary
So galaxy evolution has gotten a lot So galaxy evolution has gotten a lot more complicated.more complicated.
We need another pioneer like Strom We need another pioneer like Strom to help make sense of it allto help make sense of it all
Strom’s legacy as a scientist is a Strom’s legacy as a scientist is a model of how to leverage all model of how to leverage all wavelengths to get a fully integrated wavelengths to get a fully integrated physical view. We should all physical view. We should all remember this is how astronomy is remember this is how astronomy is done.done.
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