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A Window on Cosmic Birth:

A Window on Cosmic Birth:

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A Window on Cosmic Birth:

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  1. A Window on Cosmic Birth: Exploring our Origins with the SIRTF and NGST Space Missions Judith L. Pipher University of Rochester

  2. Searching for Origins • How did galaxies form in the early universe? • How were galaxies different at early times? • When did galaxies first appear? • How do galaxies evolve? • Do galaxy collisions play a role? • What are galaxy luminosity sources? As evolve? • How and when do stars (and planets) form? AAPT/APS Joint Fall Meeting

  3. Big Themes Big Space Experiments - IR • SIRTF - Space InfraRed Telescope Facility • cold, 0.85-m telescope; 7/02 launch • cameras 3 - 8 mm; spectrometers 5 - 40 mm; photometers 24, 70, 160 mm; lo-res spectrometer 52-99 mm • NGST - Next Generation Space Telescope • cold, 8-m telescope, planned for /08 launch • successor to the Hubble Space Telescope AAPT/APS Joint Fall Meeting

  4. Why Infrared - IR? • Cool objects radiate in the infrared • lmax T-1 Wien’s blackbody law(e.g. T=100K, lmax =30 mm = 30,000 nm) • Dusty clouds (= stellar nurseries) redden & extinguish light from forming objects • extinction factor e-tl, where tl  l-n where n =12 • Distant galaxies recede from us • recession speed dependent on the distance • red-shift z = Dl/l shifts galaxy emission to red, IR (e.g. Ha 656.3 nm  4.6mm at z=6) AAPT/APS Joint Fall Meeting

  5. Why Space? • Earth and its atmosphere bright in the IR • T ~280K blackbody peaks at l~10 mm = 10000 nm • Atmosphere blocks out much of the IR • from l = 0.8 mm - 1000 mm = 1 mm • Atmosphere makes point-like objects fuzzy • “seeing” - atmospheric motion distorts image • space experiments can be diffraction limited (q ~ l/D where D = telescope diameter) AAPT/APS Joint Fall Meeting

  6. SIRTF and NGST Detector Array Development • SIRTF’s Infrared Array Camera using InSb arrays developed at UR • 256 x 256 pixels; 5’ field of view • NGST - detector array selection in 2002 • 8Kx8K focal plane, diffraction limited at 2 mm • UR working on NGST detector technologies • SIRTF and NGST Scientific Requirement • all instruments to be background limited - this requirement means ultra-low dark current, ultra-low noise IR detector arrays AAPT/APS Joint Fall Meeting

  7. SIRTF Background(# of detected photons/s-pix vs ) • Fluctuations in background radiation are noise source • for l = 1-5mm, read noise < 10 e- and dark current < 1 e-/s • for NGST - noise < 3 e- and dark current < 0.005 e-/s AAPT/APS Joint Fall Meeting

  8. SIRTF - A Window onCosmic Birth SIRTF will be considerably more sensitive at wavelengths between 3 and 200 m than previous IR missions, primary science goals  Origins themes • The Early Universe • Ultra-luminous IR galaxies - ULIRG • Proto-planetary disks • Brown Dwarf stars AAPT/APS Joint Fall Meeting

  9. The Early Universe • All objects in HDF - Hubble Deep Field - are galaxies • Small, faint red objects the most distant (z  3.4) • SIRTF, NGST will study in IR to higher z (earlier times in the universe) AAPT/APS Joint Fall Meeting

  10. The Early Universe (HST)Composite Visible and IR View • Blue = visible • Green = 1.1 mm (1100 nm) • Red = 1600 nm • Red objects could be distant, or dusty, or contain old stars • need spectroscopy or other method to identify redshift z = l/Dl AAPT/APS Joint Fall Meeting

  11. NGST - Visiting a Time When Galaxies Were Young NGST primary science goals (large, diffraction limited IR telescope - q ~ 0.05”) A Search for Galaxy Origins • HST - Hubble Deep Field (galaxies that formed a few by after Big Bang) • NGST - will probe the era between that probed by COBE (300,000 - 106 yr after Big Bang and the era probed by HST • to identify when galaxies form, state of universe AAPT/APS Joint Fall Meeting

  12. Discovery Space for NGST

  13. Faint, Red Distant Galaxies • Investigators have produced UV-NIR images of a faint galaxy. NIR signature identifies it as distant, red-shifted galaxy: expands upon “Lyman drop-out galaxy” technique exploited on HST AAPT/APS Joint Fall Meeting

  14. Nearby Dwarf Galaxies • Nature of objects contributing to the faint blue galaxy counts unknown • Irregular, peculiar galaxies in composite colors (HST) formed at similar rates at higher z - but faint • Bright blue = episode of star formation AAPT/APS Joint Fall Meeting

  15. Galaxies asCosmological Tools • Studies of galaxies probe cosmology in several ways • galaxies at z 1 have significant ‘look-back time’ - or early age (0.4 current age) • quasars & luminous galaxies observed to redshifts z ~ 6 • space density as function of z • star formation rates as function of z, morphological galaxy type • important to study distribution of average and dwarf galaxies to higher z • need contributions to extragalactic background AAPT/APS Joint Fall Meeting

  16. Mapping Dark Matter at High z with Gravitational Lensing • HST image of massive galaxy cluster A2218: can deduce Mgal+halo • NGST simulations of lensed features for broad distribution of galaxies to z ~ 10, with evolution applied, and size-dependence with z  deduce core size of cluster mass dist’n AAPT/APS Joint Fall Meeting

  17. Starburst Galaxies • luminous nearby galaxies have bursts of massive star formation taking place - NGC 4214 • during starburst epoch(s) galaxy luminosity can be 100-1000 x Milky Way luminosity • starburst triggers? AAPT/APS Joint Fall Meeting

  18. Starburst Activity Quantified • Star formation rate a function of z (age) normalized to the present epoch • HST observations suggest steep rise in starburst soon after the Big Bang; ground-based observations show decline • HST, SIRTF, NGST probe the peak and early times AAPT/APS Joint Fall Meeting

  19. Ultraluminous Galaxies • Some galaxies are ULIRG - ultraluminous infrared galaxies - 1000 x luminosity of Milky Way galaxy • Many of these are examples of multiple colliding systems • Relation to starbursts? AGNs? AAPT/APS Joint Fall Meeting

  20. The Early UniverseVisible and Deep X-Ray View • 6 galaxies in the HDF N are X-ray emitters • one, an extremely red edge-on spiral, hosts AGN (Active Galactic Nucleus with accretion disk, 109 M black hole) • AGN • 3 ellipticals • 1 spiral • X-ray sources: AGN; hot gas emission; X-ray binary AAPT/APS Joint Fall Meeting

  21. Formation of Stars • Well established that stars form in GMCs (giant molecular clouds), and that formation of a disk and high velocity outflows a signature • yields important information on cloud support; how angular momentum conserved as protostars shrink • Stars blow away disk as evolve to main sequence • If star forms planetary system, onset of debris disk AAPT/APS Joint Fall Meeting

  22. Disks and Jets • HH111 shows pair of 12 ly jets blasted from system of 3 stars located near a tilted edge-on dusty torus, episodic ejections • NGST will image in close to the central YSO - both SIRTF and NGST can extend sample to nearby galaxies AAPT/APS Joint Fall Meeting

  23. Debris and Proto-planetary Disks • IRAS discovered that ordinary stars had disks emitting in the far IR • Many examples studied with a coronograph from the ground - most famous example,  Pictoris • Early solar system had disk (proto-planetary disks) • New studies (HST, ground) show resonant gaps • SIRTF will FIR images and spectroscopy of debris disks (structure, mass, composition); NGST can exploit superior sensitivity and spatial resolution AAPT/APS Joint Fall Meeting

  24. Debris Disk b Pictoris Note resonant cleared gap - major planet Debris andProtoplanetary Disks AAPT/APS Joint Fall Meeting

  25. Brown Dwarfs • Importance of low mass “failed stars” as halo constituents in our own Milky Way Galaxy, and in clusters within our Galaxy unknown • Gliese 229B best known methane dwarf example - few dozen now known • L dwarfs - objects T <2000K; few hundred known • Spectra dominated by molecular bands • SIRTF surveys & spectroscopy; NGST surveys - contribution to mass budget AAPT/APS Joint Fall Meeting

  26. Brown Dwarfs in Orion • Swarm of Newborn Brown Dwarfs found in Orion stellar nursery AAPT/APS Joint Fall Meeting

  27. Conclusion • SIRTF and then NGST will take us back to the early times when galaxies formed, and will address • range in z that formation took place; AGN, starburst phases in galaxy evolution; pin down cosmological parameters • bottom-up or top-down scenario for star formation in galaxies; mass function of galaxies • SIRTF and NGST will define the history of planetary systems around other stars AAPT/APS Joint Fall Meeting