current and future science with nrao instruments
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National Radio Astronomy Observatory. NRAO Operations Review ~ February 29 – March 1, 2008. Current and Future Science with NRAO Instruments. Four exemplary science programs that demonstrate the synergy between NRAO instruments, and their key roles in modern, multiwavelength astrophysics. - PowerPoint PPT PresentationTRANSCRIPT
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National Radio Astronomy ObservatoryNRAO Operations Review ~ February 29 – March 1, 2008
Current and Future Science with NRAO Instruments
Chris Carilli
Four exemplary science programs that demonstrate the synergy between NRAO instruments, and their key roles in modern, multiwavelength astrophysics.
a. First galaxies: gas, dust, star formation into cosmic reionizationb. Cosmic geometry: Megamasers and a 3% measure of Ho
c. Protoplanetary disks: imaging planet formation
d. At the extremes of physics: strong field GR, TeV sources explained!
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Dark Ages
Cosmic Reionization• Major science driver for all future large area telescopes • Last phase of cosmic evolution to be tested • Bench-mark in cosmic structure formation indicating the first luminous sources
I. Radio studies of the first galaxies: gas, dust, star formation, into cosmic reionization
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• Highest redshift SDSS QSO • Lbol = 1e14 Lo
• Black hole: ~3 x 109 Mo (Willot etal.)• Gunn Peterson trough = near edge of reionization (Fan etal.)
Pushing into reionization: QSO 1148+52 at z=6.4 (tuniv = 0.87Gyr)
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• Dust mass ~ 7e8 Mo
• Gas mass ~ 2e10 Mo
• CO size ~ 6 kpc
Note: low order molecular lines redshift to cm bands
mm/cm: Gas, Dust, Star Form, in host galaxy of J1148+5251
1” ~ 6kpc
CO3-2 VLA z=6.42
• 30% of z>6 SDSS QSO hosts are HyLIRGs
• Dust formation? AGB Winds take > 1.4e9yr > age Universe
=> dust formation associated with high mass star formation?
LFIR = 1.2e13 Lo
MAMBO/IRAM 30m
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FIR excess -- follows Radio-FIR correlation: SFR ~ 3000 Mo/yr
CO excitation ~ starburst nucleus: Tkin ~ 100K, nH2 ~ 1e5 cm^-3
Radio-FIR correlation
50KElvis QSO SED
Continuum SED and CO excitation: ISM physics at z=6.42
NGC253
MW
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[CII] 158um at z=6.4: dominant ISM gas coolant
[CII] PdBI Walter et al.
z>4 => FS lines redshift to mm band
L[CII] = 4x109 Lo (L[NII] < 0.1 L[CII])
[CII] similar extension as molecular gas ~ 6kpc => distributed star formation
SFR ~ 6.5e-6 L[CII] ~ 3000 Mo/yr
1”
[CII] + CO 3-2
[CII]
[NII]
IRAM 30m
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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..
z=10
• Rapid enrichment of metals, dust, molecules
• Rare, extreme mass objects: ~ 100 SDSS z~6 QSOs on entire sky
• Integration times of hours to days to detect HyLIGRs
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(sub)mm: high order molecular lines. fine structure lines -- ISM physics, dynamics
cm telescopes: low order molecular transitions -- total gas mass, dense gas tracers
Pushing to first normal galaxies: spectral lines
FS lines will be workhorse lines in the study of the first galaxies with ALMA.
Study of molecular gas in first galaxies will be done primarily with cm telescopes
SMA
ALMA will detect dust, molecular and FS lines in ~ 1 hr in ‘normal’ galaxies (SFR ~ 10 Mo/yr = LBGs, LAEs) at z ~ 6, and derive z directly from mm lines.
, GBT
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cm: Star formation, AGN
(sub)mm Dust, cool gas
Near-IR: Stars, ionized gas, AGN
Arp 220 vs z
Pushing to normal galaxies: continuum
A Panchromatic view of galaxy formation
SMA
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II. Cosmic geometry: Ho to few % with water maser disks.Why do we need an accurate measure of Ho?
To make full use of 1% measures of cosmological parameters via Planck-CMB studies requires 1% measure of Ho -- covariance!
with Ho constraint
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Measuring Distances to H2O Megamasers
Two methods to determine distance:
• “Acceleration” method
D = Vr2 / a
• “Proper motion” method
D = Vr / (d/dt)
NGC 4258
2Vr
2
D = r/
a = Vr2/r
D = Vr2/a
Vr
Herrnstein et al. (1999)
D = 7.2 0.5 Mpc
• Recalibrate Cepheid distance scale
• Problem: NGC 4258 is too close
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The Project (Braatz et al.) 1. Identify maser disk galaxies with GBT into Hubble flow ~ 50 currently2. Obtain high-fidelity images of the sub-pc disks with the High
Sensitivity Array (VLBA+GBT+Eff+eVLA) ~ 10% are useful3. Measure internal accelerations with GBT monitoring4. Model maser disk dynamics and determine distance to host galaxy
Goal: 3% measure of Ho
GBT
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UGC 3789: A Maser Disk in the Hubble Flow
Discovery: Braatz & Gugliucci (2008)VLBI imaging: Reid et al. (in prep)Distance/modeling: Braatz et al. (in prep)
Acceleration modeling
D ~ 51 MpcHo = 64(+/-7)
Already at HST Key project accuracy with 1 source!
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HST
• SMA 350 GHz detection of proplyds in Orion
• Derive dust mass (>0.01Mo), temperature
III. Protoplanetary disks and planet formation
Williams et al.
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TW Hya Disk: VLA observations of planet formation
Calvet et al. 2002
mid-IR “gap”
cm slope ”pebbles”
Pre-solar nebula analog
• 50pc distance
• star mass = 0.8Mo
• Age = 5 -- 10 Myr
• mid IR deficit => disk gap caused by large planet formation at ~ 4AU?
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TW Hya Disk: VLA observations of planet formation
Hughes, Wilner +
VLA imaging on AU-scales:
• consistent with disk gap model
• cm probes grains sizes between ISM dust and planetesimals (~1cm)
Dec= -34
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ALMA 850 GHz, 20mas res.
Wolfe +
Birth of planets: The ALMA/EVLA revolution
Radius = 5AU = 0.1” at 50pc
Mass ratio = 0.5MJup /1.0 Msun
Wilner
• ALMA: AU-scale imaging of dust, gas, unhindered by opacity, nor confused by the central star
• EVLA: AU-scale imaging of large dust grain emission
• JWST: image dust shadow on scales 10’s mas
• Herschel: dust spectroscopy
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TW Hya -- Molecular gas
SMA: Gas mass, rotation
ALMA: dynamics at sub-AU, sub-km/s resolution
SMA
ALMA simulation
Wilner
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Credit: Bill Saxton, NRAO
IV. At the extremes of physics
• Extreme gravity: using pulsars to detect nHz gravity waves
• TeV sources: explained by VLBI!
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Gravitational Wave Detection using a ‘pulsar timing array’ with NANOGrav (Demorest +)
D. Backer
Predicted timing residualsPredicted timing residuals
• Need ~20-40 MSPs with ~100 ns timing RMS
• bi-weekly, multi-freq obs for 5-10 years
• Timing precision depends on
- sensitivity (G/Tsys) (i.e. GBT and Arecibo)
- optimal instrumentation (GUPPI -- wideband pulsar BE)
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Credit: D. Manchester, G. Hobbs
NanoGrav
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Discovered 1976 @ 100 MeV; variable 5 GHz emission.
High mass binary: 12 Mּס Be * , 1–
3Mּס NS or BH.
Eccentric orbit e=0.7, period 26.5 days.
X-rays peak @ periastron, radio 0.5 cycle later.
TeV detected by Magic
MODELS:
(A) Accretion powered relativistic jet (microQuasar?)
(B) Compact pulsar wind nebula
LS I +61 303: Solving the TeV mystery
> 400 GeV
Xray
Radio
Albert+ 2006
Harrison + 2000
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VLBA Images vs. Orbital Phase(orbit exaggerated)
VLBA movie shows 'cometary' morphology => a Pulsar Wind Nebula shaped by the Be star envi-ronment, not a relativistic jet.
Dhawan +
VLBA resolution ~ 2AU
Be
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Gamma-Rays from AGN Jets• GLAST launch
scheduled for May 2008
• VLBA jet imaging on pc-scales during flares required to understand gamma ray production
• Prelaunch survey: VIPS project to image 1100 objects (Taylor et al.)
• Planned: 43 GHz + GLAST monitoring of gamma ray blazars
Marscher et al.
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NRAO in the modern context
Golden age of astrophysics: NRAO telescopes play a fundamental role in topical areas of modern astrophysics• Precision cosmology: setting the baseline (Planck ++)
• Galaxy evolution and first (new) light: gas, dust, star formation (JWST, TMT)
• Birth of stars and planets: dust and gas on AU scales (JWST, Herschel)
• Testing basic physics: GR, fundamental constants, … (LIGO, LISA)
• Resolving high energy phenomena: a ray source primer (GLAST, CONX)
Capabilities into next decade keep NRAO on the cutting edge• ALMA -- biggest single step ever in ground based astronomy
• EVLA -- the premier cm telescope on the planet, and a major step to the SKA
• GBT -- just hitting its stride, with pending FPA revolution
• VLBA -- Mankind’s highest resolution instrument
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END
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Current large programs: VLA, VLBA, GBT
AUI Operations ReviewFebruary 29 – March 1, 2008
• Radio interferometric planet search -- VLBA, VLA, GBT
• Coordinated radio and infrared survey for high mass star formation -- VLA
• Definitive test of star formation theory -- GBT
• Legacy survey of prebiotic molecules toward Sgr B2 and TMC-1 -- GBT
• Detecting nHz gravitational radiation using pulsar timing array -- GBT
• Star Formation History and ISM Feedback in Nearby Galaxies -- VLA
• LITTLE THINGS survey: HI in dwarf galaxies -- VLA
• Megamaser cosmology project -- GBT, VLBA, VLA
• Probing blazars through multi-waveband variability of flux, polarization, and structure -- VLBA
• MOJAVE/GLAST program: mas imaging of gamma ray sources -- VLBA
• VLA low frequency sky survey -- VLA
• Deep 1.4 GHz observations of extended CDFS -- VLA
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GR tests: Timing of the Double Pulsar J0737-3039
GBT provides the best timing precision for this system
6 post-Keplerian orbital terms give neutron star masses
strong-field tests of GR to 0.05% accuracy
Measure relativistic spin precession:
Obs = 5.11+/- 0.4 deg/yr
GR = 5.07 deg/yr
Kramer et al., 2006, Science, 314, 97