Definitions
Linear Neural Networks
- Perceptron
- Adaline
- Stochastic Gradient Descent
Classifiers
- Logistic Regression
- Support Vector Machines
- Decision Trees
- K-Neighbors
Perceptron
- Present the training data in a random order.
- Weights are updated using a unit step function
- Eta: The learning rate is a hyperparameter that controls how much to change the model in response to the estimated error each time the
model weights are updated... i.e. Controls the rate or speed at which a model learns
- Choosing the eta is challenging, and is totally trial and error.
Adaline (Adaptive Linear Neuron)
- Weights are updated using a linear activation function
- Minimizing a continous cost function
- Feature scaling: different data range for different features
Stochastic Gradient Descent
- Present the training data in a random order.
- Minimizing a cost function
- Eta: The learning rate is a hyperparameter that controls how much to change the model in response to the estimated error each time the
model weights are updated... i.e. Controls the rate or speed at which a model learns
- Choosing the eta is challenging, and is totally trial and error (default: 0.1 or 0.01)
Course Description
This course is intended for all graduate students and provides an introduction to galaxies and extragalactic astronomy. The emphasis is on making the connection between what we can observe about galaxies and the more fundamental physical properties that we would like to know about the galaxies themselves. We will cover the main techniques used for observing galaxies (imaging, spectroscopy, distance methods, extragalactic surveys), the observed properties (morphology, colors, luminosity functions, surface brightness profiles, kinematics, scaling relations, and spectral energy distributions), and the basic components that make up individual galaxies (stars, gas, dust, central black holes, dark matter) like our own Milky Way. The companion class, ASTR 616 - Galaxies II, builds on this foundation to explore the underlying principles of galaxy formation, galaxy evolution, and cosmology.