Science Group: Status, Plans, and Issues

Claire Max

Liz McGrath

August 19, 2008

Outline

• What have we accomplished since the SDR?

• Plans for the next six months and the next year

• Issues

What have we accomplished since the SDR?

• Science Cases: – Progress on

• Astrometry science• Resolved stellar populations in crowded fields

– Modest progress on• Debris disks and young stellar objects• QSO host galaxies• Gravitational lensing

• Phased development: – Extragalactic science case: high z galaxies of various kinds

• Worked through science priorities for this example• Implications for phased development and instrument capabilities

Astrometry Science• Example: Proper motion studies of compact objects constrain their

birthplaces and lifetimes. • Magnetars (possible link to GRBs) and their connection to standard

pulsars:

• Additional astrometry topics: faint binary companions, clusters (to eliminate foreground stars for accurate color-magnitude diagrams), and transient events (important in era of LSTT and PANSTARRS).

– Supernova explosion imparts

initial “kick” to the neutron star.

– Comparison between measured

space velocities and physical

models will help elucidate

whether there is an evolutionary

sequence between magnetars

and pulsars, or whether their

differences are due solely to

their birthplace.

Resolved Stellar Populations in Crowded Fields

• Goal: obtain accurate photometry of a statistically significant sample of stars in short-lived phases of stellar evolution. – Currently, very little is known about these short-lived phases of stellar

evolution, but they often contribute significantly to the integrated spectral energy distribution of a galaxy.

– Important to get a better handle on these phases of stellar evolution in order to improve stellar population synthesis models which are used in a wide variety of astronomical science.

1. AO reduces confusion due to stellar overlap

2. Reduced confusion and higher Strehl yield better photometric accuracy

3. Faint stars become visible once the confusion noise is reduced

• MOAO has advantage over MCAO for some science cases: nearby dwarf galaxies, or denser environments such as globular clusters where increased Strehl is the payoff.

Phased development for extragalactic science

• Enclosed energy of order 0.05 - 0.07 arc sec

• Priorities:

– Tied for first place:

• high sensitivity (high throughput, low background, cooled AO, …)

• high sky coverage (IR-corrected tip-tilt stars)

– Third place:

• More area in field of view of an OSIRIS-like IFU

– Fourth place:

• Multiplicity (many IFU heads)

• Implications:

– Optimize design of AO for the on-axis narrow-field IFU

• If the d-IFS is never built, will still have big advance over current system

– These same priorities apply to the deployable IFS

Plans for next six months: Science Requirements

• With a new Science Advisory Team:

• Deepen science cases for Key Science Drivers + Science Drivers

– Simulations and analysis leading to quantitative requirements on

• Sensitivity

• PSF (see below)

• Spatial sampling

• Coronagraphs and achievable contrast ratios

• PSF issues

– Develop definitions of PSF requirements for each science case

• PSF stability versus PSF knowledge

• Quantitative characterization of aspects of the PSF that are crucial for each specific science case ("PSF accurate to 5%" doesn't mean much)

• Astrometry issues

– In crowded fields like Galactic Center or cores of globular clusters

– In sparse fields

Plans for the next year: Observing Planning and Execution

• With David Le Mignant and a new Science Advisory Team:

• Develop Observing Scenarios for all of the Key Science Drivers

• Plan a "Design Reference Mission" for at least two Key Science

Drivers

• Provide science input to the Preliminary Operations Concept

Document

Plans for the next year: Science Input to Other WBS Elements Affecting Science Performance

• Simulations for science drivers using PSFs of varying uncertainties

• Define specific Science Driver parameters for use in performance budgets

• Evaluate and suggest new user interfaces, planning, and observing tools

• Input to Preliminary Operations Concept Document

Plans for the next year:Science Competitiveness

• Maintain up to date knopwledge and list of current and future science goals being carried out at other facilities

• Evaluate potential for NGAO to complement these observations

• Refine NGAO uniqueness space

Plans for the next year: User Community Liaison and Science Advisory Team

• Observatory Directors have committed to appoint a Science Advisory Team

• Team members and others will help develop and refine science cases, implications for AO and instruments

• Will help develop and test concepts for observing planning tools, user interfaces, data products

• Evaluate implications of cost cap and phased development options

Issues• What should be emphasis: phased development versus AO versus

instrument design requirements?

• What is the nominal instrument suite?

– Example: what to do (if anything) about a visible IFU (e.g. for black hole mass measurements using Ca triplet lines)

• Science Advisory Team:

– What is the best way for Claire to provide input, suggestions?

– When will Directors appoint the team?

• What do we really need to know about PSFs?

• Who will actually do the science simulations?

– Astrometry?

– Exposure time calculator for the various instruments?

– Black hole mass measurements? etc