1. The Transient Universe: AY 250 Spring 2007 Parameter Space and the Time Domain Geoff Bower

2. The Transient Universe: AY 250 Spring 2007 The Unknown As we know, There are known knowns. There are things we know we know. We also know There are known unknowns. That is to say We know there are some things We do not know. But there are also unknown unknowns, The ones we don't know We don't know. —Feb. 12, 2002, Department of Defense news briefing

3. The Transient Universe: AY 250 Spring 2007 Zero-Order Science

4. The Transient Universe: AY 250 Spring 2007 Expansion of Parameter Space  Discovery Cosmic Discovery, Harwit 1984 Astronomical parameter space –Sensitivity –wavelength –angular resolution –spectral resolution –time resolution  –polarization –particle mode How do we verify this assertion?

5. The Transient Universe: AY 250 Spring 2007 Galileo Uses the Telescope Telescope first engineered in Holland in 1608 Galileo obtains one and makes use of it for astronomical observations in 1610 Discovers –Moons of Jupiter –Mountains on the Moon –Phases of Venus Technology is passed on for military purposes

6. The Transient Universe: AY 250 Spring 2007 Discovery of Gamma-Ray Bursts Vela Nuclear Test Detection satellites launched 1963-1970 Successive improvement in sensitivity Searches for gamma-rays from supernovae turned up nothing (motivated by Colgate & Teller) Detection of coincident bursts in 1969 Accumulation of data and high angular resolution location led to understanding that associates GRBs with death of massive stars at high red shift

7. The Transient Universe: AY 250 Spring 2007 Superluminal Motion Rees (1967) predicted phenomenon of bursts from quasars Independently & unaware, Shapiro & colleagues (1970) observed 3c 273 and 3c279 to detect gravitational effects of the Sun Detected motions of ~10c Robertson & Moffett (1967) detected superluminal motion in 3c 273, were aware of Rees article, but retracted conclusions Biretta 1999

8. The Transient Universe: AY 250 Spring 2007 Systematic Characterization of Parameter Space Harwit 2003

9. The Transient Universe: AY 250 Spring 2007

11. Parameter Space  Discovery How well do discoveries fill the parameter space? Are there significant voids? Do filled regions indicate full exploration?

12. The Transient Universe: AY 250 Spring 2007 Harwit argues that new phenom. is easily recognizable by a working scientist Factor of 1000 in any parameter

13. The Transient Universe: AY 250 Spring 2007 Trends of Discovery Most important discoveries result from substantial technological innovation Following a new technique, discovery follows quickly Novel instrument soon exhausts its capacity for discovery New discoveries are often made by physicists or engineers from outside astronomy Many discoveries involve military technology Instruments used in the discovery were often constructed by the discoverer Discoveries often occur by chance

14. The Transient Universe: AY 250 Spring 2007 When Are Discoveries Made?

15. The Transient Universe: AY 250 Spring 2007 Who Makes Discoveries?

16. The Transient Universe: AY 250 Spring 2007 The Role of Theory Explanation of known phenomena Breakthrough in understanding through technical development –Newton’s invention of calculus But has theory predicted discovery of a new phenomenon?

17. The Transient Universe: AY 250 Spring 2007 How Much Is Left to Be Discovered? Harwit 1984 makes counting arguments that suggest 10 – 30% of all discoveries have been made Time scale for discoveries are centuries to millenia

18. The Transient Universe: AY 250 Spring 2007 Rediscovery of Phenomena Factor of 1000 difference in telescope parameters required for rediscovery 7/43 phenomena re- discovered  125 total phenomena

19. The Transient Universe: AY 250 Spring 2007 Rediscovery of Phenomena Exponential growth in phenomena –1550-1800: N=4  11 –1800-1950: N=11  30 –Tau ~ 200 years

20. The Transient Universe: AY 250 Spring 2007

21. Fraction of Parameter Space Observed Harwit estimates 1% Known number of unimodal phenomena is ~few –Gamma-ray bursts –Gamma-ray background –X-ray background –Unidentified radio sources  Total unimodal phenomena is hundreds  10% of phenomena known

22. The Transient Universe: AY 250 Spring 2007

23. Alternative View of Growth of Phenomena Linear growth of knowledge Constant ratio of papers/astronomers over 30 years Technological growth & volume of data is not enabling more discovery/astronomer Abt 2000

24. The Transient Universe: AY 250 Spring 2007 Examples of Parameter Space Motivated Instruments or Searches

25. The Transient Universe: AY 250 Spring 2007 Optical Transient Parameter Space Kulkarni 2006

26. The Transient Universe: AY 250 Spring 2007 Kulkarni 2006

27. The Transient Universe: AY 250 Spring 2007

28. Monitoring All Sky for Variability (Paczynski 2000) Few percent of stars are variable 90% of variables brighter than 12 th mag undiscovered All sky surveys can discover many more Compile complete samples for statistics Clean examples Rare objects or events Generate variability archive for the future

29. The Transient Universe: AY 250 Spring 2007 The SKA and the Unknown (Wilkinson et al 2004) Harwit & parameter space arguments figure directly into argument for SKA

30. The Transient Universe: AY 250 Spring 2007

31. The SKA and the Unknown (Wilkinson et al 2004) Harwit & parameter space arguments figure directly into argument for SKA Lessons from discovery –Radio discoveries have set astronomical agenda –Majority of discoveries were not direct result of theory –Largest telescopes dominate discovery –What telescope was built for is not what it is known for –General purpose telescopes now dominate discovery

32. The Transient Universe: AY 250 Spring 2007 SKA Design & Discovery Utilize new technologies Expand sensitivity Expand parameter space Define observing modes that explore new parameter space –Transient & survey modes highlighted Change culture of observing to support innovation Archive data for re-analysis