High Frequency (> 10GHz) Thermal science at centimeter wavelengths, and more! Chicago III, Sept. 15,...
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Transcript of High Frequency (> 10GHz) Thermal science at centimeter wavelengths, and more! Chicago III, Sept. 15,...
High Frequency (> 10GHz)
Thermal science at centimeter wavelengths, and more!
Chicago III, Sept. 15, 2007
Washington DC
Chris Carilli (NRAO)
Laundry list of high frequency science with SKA
(what we lose without >10GHz)
• First light: molecular line studies of the first galaxies**
• Cradle of life: Terrestrial planet formation and pre-biotic molecules
• Cosmology: Extragalactic water masers and measurement of Ho
• Testing GR: Pulsars in the Galactic Center
• SZ effect at 30GHz
• Molecular abs line systems and the variation of the fundamental constants
• Stellar masers (SiO, H2O) -- late stages of stellar evolution
• NH3
• Solar system thermal objects: atmospheres, surfaces, asteroids, KBO, comets
• Spacecraft tracking and telemetry at 32GHz: movies from Mars
• Stellar photospheres, winds, outflows
• FF/RRL -- HII regions, SuperStarClusters ….
**Key Science Projects
ALMA/EVLA CO redshift coverageEpoch of Reionization:Benchmark indicating formation first luminous Objects = Last frontier
First galaxies: standard molecular transitions redshift to cm regime
•Total gas mass
•Gas dynamics
•Gas excitation
•High density gas tracers
CO Excitation
ladder
Weiss, Walter, Downes, Henkel, in prep.
ALM
A z
~1
0
Starbursts
Normal galaxies
^2
First galaxies -- Radio astronomy into cosmic reionization
z ~ 6 QSO host galaxies: molecular gas and dust
• Giant reservoirs of molecular gas ~2e10 Mo = fuel for star formation.
• Currently: 2 solid detections, 2 likely at z~6
FWHM=350 km/s
z=6.42
Radio-FIR correlation
50K
Mdust ~ 1e8 Mo
Dust heating: star formation or AGN?
Follows Radio-FIR correlation: SFR ~ 3000 Mo/yr
VLA
PdBI
J1148+52: VLA imaging of CO3-2
Separation = 0.3” = 1.7 kpc
TB = 20K => Typical of starburst nuclei
rms=50uJy at 47GHz
Not just circumnuclear disk.
Can AGN heat dust kpc-scales (geometry/rad transfer)?
1” 5.5kpc
0.4”res
0.15” res
VLA imaging of gas at subkpc resolution
Gas dynamics: Potential for testing MBH - Mbulge relation at high z -- only direct probe of host galaxies
Mdyn~ 2e10/(sin)^2 Mo
Mgas~ 2e10 Mo
Mbulge ~1e12 Mo (predicted)
1148+5251 z=6.42
z<0.5
MBH = 0.002 Mbulge
[CII] 158um ISM gas cooling line at z=6.4 30m 256GHz
Maiolino etal
CII PdBI Walter et al.
C+ = workhorse line for z>6 galaxies with ALMA
Structure identical to CO 3-2” (~ 5 kpc) => distributed gas heating = star formation?
SFR ~ 6.5e-6 L[CII] ~ 3000 Mo/yr
1”
CII + CO 3-2
Higher Density (>1e4 cm^-3) Tracers: HCN, CN, & HCO+,
HCO+ 1-0
•Cloverleaf (z=2.56) = SgrB2 of distant galaxies•Lines 5-10x fainter than CO•ncr > 1e7cm^-3 for higher orders => higher order not (generally) excited?•Dense gas tracers best studied with cm telescopes
HCN 1-0
200uJy
Riechers
CO vs. HCN: total vs. dense gas
Index = 1
HCN traces dense gas (> 1e4 cm^-3)
SFR / dense gas mass ~ universal in all galaxies: ‘Counting star forming clouds’
Index=1.5
• CO traces all molecular gas (>100 cm^-3)
• SFR / total gas mass = star formation efficiency, increases with FIR luminosity.
FIR
L’(CO) L’(HCN)
1e13
1e9
Building a giant elliptical galaxy + SMBH at tuniv < 1Gyr
Multi-scale simulation isolating most
massive halo in 3 Gpc^3 (co-mov)
Stellar mass ~ 1e12 Mo forms in series (7) of major, gas rich mergers from z~14, with SFR ~ 1e3 - 1e4 Mo/yr
SMBH of ~ 2e9 Mo forms via Eddington-limited accretion + mergers
Evolves into giant elliptical galaxy in massive cluster (3e15 Mo) by z=0
10.5
8.1
6.5
Li, Hernquist, Roberston..
• Enrichment of heavy elements, dust starts early (z > 8): good news for radio astronomy
• Extreme and rare objects: ~ 100 SDSS z~6 QSOs on entire sky
• Integration times of hours to days to detect HyLIGRs
10
(sub)mm: high order molecular lines + fine structure lines
cm telescopes: low order molecular transitions
The need for collecting area: pushing to normal galaxies at high redshift -- spectral lines
cm: Star formation, AGN
(sub)mm Dust, molecular gas
Near-IR: Stars, ionized gas, AGN
Arp 220 vs z
The need for collecting area: continuum
A Panchromatic view of galaxy formation
Bryden 1999
The Cradle of Life (Wilner)
• image terrestrial planet formation zone of disks– grain growth to pebbles
– embedded protoplanets and sub-AU tidal gaps
– Evolution ~ 1 year
• assess biomolecules– disk abundances
– locations
Remijan et al. 2006Remijan et al. 2006
• T Tauri, Herbig Ae stars: several l00’s of proto-Sun analogs, d ~ 140 pc, age 1-10 Myr
– How do terrestrial planets form? – How much orbital evolution (migration)? – Is our Solar System architecture typical?
• SKA: unique probe of disk habitable zone– mas resolution: 1AU = 7mas at 140pc– cm waves: avoid dust opacity– very high sensitivity: thermal emission
• Complementarity – ALMA: Chemistry, dynamics, dust on larger scales– Optical: scattered light
stardust
1.3 mm1.3 mm
Terrestrial Planet Formation
• SKA 8hrs, 22GHz, 2mas (1500km) =>
S(rms) = 0.02uJy, TB(rms) = 11K
• flux density emitted by a disk element dA
TB ~ 50 to 300 K on AU scales
• less than an Earth mass in sub-AU beam at 140 pc distance of nearby dark clouds
SKA Sensitivity: thermal science at mas resolution
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Embedded Protoplanets
• protoplanet interacts tidally with disk– transfers angular mom.– opens gap– viscosity opposes
• orbital timescales in habitable zone are short (t ~ 1 yr)
• synoptic studies track proper motions of mass concentrations
P. Armitage
Bate et al.
1AU Gap ~ 100 K
Grain Growth and Settling• detailed frequency dependence of dust emissivity
is diagnostic of particle properties, esp. size• SKA sensitive to cm sizes, predicted to settle to
disk mid-plane and seed planetesimals -- sticky question?
TW Hya3.5 cm dust
Wilner et al.
NASA/JPL R. Hurt
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Cosmology -- Water maser disks (Greenhill)
• Hubble constant through direct measurement of distances to galaxies in the Hubble flow.
• Distance to NGC 4258 = 7.4 Mpc +/- 4%
-- maser acceleration and proper motion
-- problem: NGC 4258 is too close => Cepheid calibrator
• Earth baselines => resolution > 0.4 mas => max. distance ~ 120 Mpc
• Currently ~ 30 NGC4258-like masers known
• SKA: ~ 100x more sources, with adequate sensitivity to image => easily 1% measure of Ho
Why do we need to know Ho to 1% ?
Future 1% measures of cosmological parameters via CMB studies require 1% measure of Ho for fully constrained cosmology: covariance!
Current Ho constraint
10% 4%
0.09
0.13
(w)
Ho accur.
Spergel et al. 2006
w ~ 1 +/-
GR tests: Galactic Center Pulsars (Cordes)
•Sgr A* = 3106 black hole with a surrounding star cluster with ~ 108 stars. Many of these are neutron stars.
•Detecting pulsars near Sgr A* is difficult because of the intense scattering screen in front of Sgr A*: d ~ 2000 ν-4 sec (but S ^-3)
•Solution: high sensitivity at high frequency: > 10GHz => width < 0.2sec
Key science:
• Highest probability of finding binary BH-pulsar: strong field GR tests and BH spin.
• Possibly 1000 pulsars orbiting Sgr A* with orbital periods < 100 yr
• Detailed studies of GC ISM -- DM…
Summary and Ruminations
KSP 10% Big step? Up to 45GHz? >1000km?
First light: mol. lines Y Y N
Terrestrial planet formation: PP disks
Y Y Y
Gal. Center Pulsars Y N N
Cosmology: water masers and Ho
Y N Y
• SKA-High is not being pursued by international partners.
• SKA-High is most consistent with current work in USA (EVLA, ATA, DSN).
Rayleigh-Jeans curve implies thermal objects are a factor four stronger (in Jy) at 45GHz relative to 22GHz => a 10% demonstrator becomes 40% of the SKA-22,
Or EVLA at 45GHz ~ 8% SKA-22GHz demonstrator
10% demonstrator
Case for frequencies up to 45 GHz: Thermal objects
0.1 x Arp220
25-50GHz
What we lose without 3 -- 10 GHz
• mas resolution -- Astrometry! Jets, AGN, XRBs
• GRBs, RSNe
• Methanol masers: massive star formation
• Large RM sources
• ms Pulsars with moderate DM
….
END