Time Domain Studies on 8m Telescopes

1. Time Domain Studies on 8m Telescopes • Some Examples • Supernovae • Gamma Ray bursts • Variable Stars • Microlensing and the Metallicity of the Bulge • Gamma Ray bursts and the IGM • Planetary Transits • The Sociological Challenge • A Basis for Discussion

2. The Supernova Industry • Largely focused on finding Type Ia SN at intermediate redshift for cosmology – mostly on 4m (e.g. SNLS) • Rates ~few/sq deg/month • Optical for z<1, need IR for z>1, very difficult from ground • Classification – either light curves or spectroscopy to eliminate non-Type Ia’s • Need sampling ~weekly or spectrum near peak (~month)

3. Gamma Ray Bursts • Early time light curves to search for high-z bursts – IR bright, optically faint • Late time light curves to understand physics of emission – search for • Achromaticity • Jet breaks Dai et al. (2008)

4. Variable Stars • Distance scale (Cepheids, Eclipsing Binaries) • Massive Star Evolution (LBVs, Binary fractions) • Massive Star Outbursts (e.g.  Carina) • Supernova Progenitors (?)

6. Using Microlensing Events to Measure the Metallicity of Main Sequence Bulge Stars Use the high magnifications (100-1000) produced by some microlensing events to get high resolution spectroscopy of main sequence rather than giant stars in the bulge

7. Using GRBs to Study the ISM Prochaska et al. (2008)

8. Planetary Transits • Not done on 8m because apertures too large for read time • -- 10 mag star produces 19 million counts on LBC in 1 sec • But many science drivers for reaching such photon precisions – transit timing, in/out transit spectroscopy • Need instruments that: • Have very fast read times (e.g. IR detectors or CCDs in sub-apertures) • Poor image quality (deliberately degrade images – 5-10 arcsec for 10 mag star!) or monitor with spectroscopy (reduce saturation, average over more pixels) • Need very high stability and large enough fields to have comparison stars (want to reach sub-millimags)

9. The Sociological Challenge It’s MY (OUR) Night, Damn It!!!!!!!

10. Planning Issues Planning Horizon Months Weeks Days Hours Timing Week variables SN SN GRB GRB Day SN/GRB Hour transits lensing GRB/IGM

11. Supporting time domain science will give LBT a competitive advantage over many other 8m telescopes • Needed to make LBT competitive with the ones that use queue observing (VLT, Gemini) • Most partners are already planning to use “internal” queue observing • Ultimately, LBT can switch between instruments relatively easily

12. A Strawman Proposal Outline • Devote 5% of LBT time to time domain science across partners • Internal TACs flag such proposals • Partners are reimbursed either by their use of the cross-partner monitoring time on a 1 for 1 basis or in time on a 2 for 1 basis for imbalances in the use of the time • Why 2 for 1? To compensate for the “weather guarantee” when you get monitoring data and the time of the observing group. • Some form of standardized accounting to reconcile the accounts each year. • Start simple. LBC only, no instrument changes, weak time constraints, centralized queue of monitoring projects