Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~astro/chicago2/talks/Reid-Science_with_Future_Radio_Telescopes.pdf Дата изменения: Tue Aug 22 00:03:17 2006 Дата индексирования: Sun Dec 23 00:59:13 2007 Кодировка: Поисковые слова: aurora

Science Opportunities and Future Radio Telescopes: II.
Strong Gravity, Cradle of Life, Milky Way & Local Group

Mark Reid: Harvard-Smithsonian CfA


"Big Questions" Need Pan-chromatic Data
Big Bang: Density fluctuation seeds: CMB Recombination: CMB Dark Ages: 21 cm HI First Galaxies: EoR,BHs,Starbursts First stars: Star/Planet formation: dust, molecules, free-free Mature Planetary Systems: Ours; extrasolar Jupiters Life & Precursors: complex molecules, SETI
From "Frontier Science Enabled by a Giant Segmented Mirror Telescope" GSMT Science Working Group, June 2003 ([sic] they left out galaxy evolution!)


Strong Gravity: Imaging Super Massive Black Holes
What does the environment of a SMBH look like? How do cosmic accelerators work? Imaging super massive black holes: mm/sub-mm VLBI can directly image < 10 Rsch for Sgr A*, M 87, & Cen A See GR "shadow" of BH Synchrotron emission from Accretion disk, Magnetic connections (BH ­ disk), Jet formation / acceleration


Pulsars
Estimated ~20,000 pulsars in MW beamed toward us Measure parallax... Tomography of ionized ISM Understand formation routes Discover pulsars orbiting Sgr A* Stellar graveyard in Gal. Cen.? Find many unusual cases (eg, strong gravity): Plsr -- Plsr Plsr -- BH


Tests of Strong Gravity

What happens in Strong Gravity? Timing of Plsr ­ BH binaries can uniquely test GR in strong gravity limit


Gravitation Wave Detection
What does the GW spectrum look like? How do SMBHs merge? Stable milli-sec pulsars form a Pulsar Timing Array Uniquely detect gravitation waves at nHz freq: SMBH binaries Complements LIGO / LISA; not sensitive to low frequencies


Cradle of Life
Orion source-I How do stars of all masses form? How do accretion disks work? Image accretion disks How inflow / outflow works Critical role of magnetic fields Transfer angular momentum Deeply embedded: IR totally extincted
50 AU

Radio can see deep inside

Greenhill, Reid, Menten & Chandler


Planet Formation
How, where and when do giant planets form? How, where and when do terrestrial planets form? Do planets migrate? Image protoplanetary disks into habitable zone
10 orbitial periods

Need cm waves (avoid high optical depths, detect "pebbles") Need mas-resolution (sub-AU @ 200 pc) Need excellent brightness sensitivity Extremely dynamic processes, evolving on months to years ­ movie of protoplanetary disk

50 orbital periods Bryden et al (1999)


Future Telescopes Needed
Required image scales & brightness for Proto-Stellar Disk: 0.1-0.01 Msun in 100 AU Proto-Planetary Disk: 0.001 Msun in 10 AU Multi-wavelengths important to determine grain size vs radius & age EVLA-II complements ALMA SKA explores unique territory


Structure and Dark Matter in Milky Way
What does Milky Way look like in 3-D? Is Spiral Density Wave paradigm correct? How is the Dark Matter halo distributed? Little progress in 30 years! Need Parallaxes and Proper Motions (SIM/GAIA limited by optical extinction) SKA detects weak sources, close calibs Distances to Hyades / Pleides (<<1%) Ro (1%) thousand pulsars, stars (few %)

Georgelin & Georgelin (1976)


Mapping the Local Group
M33 VLBA has measured proper motions of 2 masers in M33 SKA-VLB could do entire Local Group Proper Motions Rotation Distances: D = Vrot / ( sin i) ~ +/- 5%


Dark Matter in Local Group
What is the history and fate of the Local Group? How much Dark Matter is in halos? How is the Dark Matter distributed? Measure 3-D locations and motions; Model dark matter halos N-body integrations yield history/future


Dark Matter in Local Group
"full" DM halos 50% DM halo

N-body calculations: sensitive to dark matter halos


Science with Current and Future National Radio Telescopes
Constraints on radio observations


Science with Current and Future Radio Telescopes
Constraints on radio observations Many significant science targets


Science with Current and Future Radio Telescopes
Constraints on radio observations Many significant science targets Current national facilities leave big gaps


Science with Current and Future Radio Telescopes
Constraints on radio observations Many significant science targets Current national facilities leave big gaps New facilities needed


Other Important Observational Parameters

Also need single-dish telescopes with large receiver arrays