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Seeing the Distant Universe inIntegral
Field Spectrosc
opyat high
redshift
3D3DAndrew Bunker, AAO & Oxford
After era probed by WMAP the Universe enters the so-called “dark ages” prior to formation of first stars
Hydrogen is then re-ionized by the newly-formed stars
When did this happen?
What did it?
DARK AGES
Redshift z
5
10
1100
2
0
B (0.45m) U (0.3m)
VV (0.6m) II (0.8m)
JJ (1.2m) HH (1.6m)
Near Infrared
Camera NICMOS
HUBBLE SPACE HUBBLE SPACE
TELESCOPETELESCOPE
z~1 HDF spiral
"3D" SpectroscopyPreviously used a "long slit" in spectroscopy -
cut down background light, become more
sensitiveRelatively new technique
- integral field spectroscopy - arrange elements to survey a 2D area (rather than a 1D
line)The spectra gives a 3rd
dimension (wavelength, or velocity)
What is CIRPASS?
Near-infrared integral field unit (spectra over a 2D area)
Built by the IoA with support of Sackler foundation & PPARC
Wavelengths 0.9-1.8m (z, J, H): doubles range of Gemini IFU science
490 spatial samples & variable image scales 0.05"-0.33" up to 5"x12" field
Large wavelength coverage (=2200Å) at R~4000: great sensitivity between OH sky lines
Limiting line flux on an 8m ~2x10-18 ergs/sec/cm^2 (53 hours)
Successfully demonstrated in August 2002 on Gemini-South telescope, community access 2003A
500 fibres IFU
Instrument cryostat
On dome floor
IFU Science
●Exquisitely sensitive to line emission redshifted between OH
●Star formation at z>1 (H, [OIII]5007Å, H, [OII]3727Å)
●Robust star formation rate measures down to
1M⊙/yr●Rotation curves, kinematics
●Masses, extinction, metallicity
●Nature of damped Lyman- systems at high-z
●Lensed galaxies/dark matter sub-clumping
●Ages of young star clusters
Gemini Integral Field Spectroscopy
– Program with Gemini Observatory to demonstrate the power of IFUs (5nights GMOS+8 nights CIRPASS)
Large interntational team (CIRPASS observations involve ~50 scientists) lead by Cambridge/Gemini/Durham
First demonstration of near-IR IFU science
Institute of Astronomy, Cambridge: Andy Bunker(AAO/Oxf), Joanna Smith (PhD student), Rachel Johnson (Oxf), Gerry Gilmore & Ian Parry, Rob Sharp, Andrew Dean etc CIRPASS team
Gemini: Matt Mountain, Kathy Roth, Marianne Takamiya, Inger Jørgensen, Jean-Rene Roy, Phil Puxley, Bryan Miller, etc. (Director's discretionary time)
Durham: Richard Bower, Roger Davies (Oxf), Simon Morris, Mark Swinbank etc. & GMOS team
Andrew Bunker, Gerry Gilmore
(IoA, Cambridge) & Roger Davies (Durham/Oxford
)
GMOS-IFU
GEMINI-NORTH
optical: Gemini Multi-Object Spectrograph
Hawaii June 02
GEMINI-SOUTH
Chile Aug '02,Mar/Jun 03
Q2237+03 - Einstein cross
Search for dark matter
substructure - Ben Metcalf,
Lexi Moustakas,
Bunker
z=1.7 QSO, z=0.04 lens
Substructure at 104M⊙<M<108M⊙ is 4%-7% of surface mass density - high compared to some CDM predictions
(but poss. variability/microlensing)
Q2237+03 - Einstein cross
Ben Metcalf, Lexi
Moustakas, Andy Bunker &
Ian Parry (2004,
accepted by ApJ, astro-ph/0309738)
Extended blue light over >5", aligned with radio
3C radio galaxy z=1.2 deep HST im.
studied by Spinrad & Dickinson
evidence of a cluster
size well-suited to GMOS/CIRPASS
study emission lines [OII] & [OIII]/H (kinematics)
A z=1.2 radio galaxy 3C324(Joanna Smith PhD)
HST B-band (rest-UV)
GMOS-IFU [OII]3727
CIRPASS [OIII]5007
HST R-band
3C324 alignment effect, with Joanna Smith (PhD student)
GMOS IFU Spectroscopy Gemini-N 3C324 z=1.21 radio galaxy -
"reduced" 2D (still has sky & cosmics, but extracted fibres)
8000Å 8300Å
[OII]3727Å @z=1.2
3C324 3-D data
cube
[OII]3727 structure has two velocity components at +/-400km/s
Wavelength/
velocity
HST B-band (rest-UV)
GMOS-IFU [OII]3727
CIRPASS [OIII]5007
HST R-band
3C324 - Smith, Bunker, et al. : alignment effect
Galaxy kinematics redshift 1!
H map of a CFRS disk galaxy
with CIRPASS (Smith, Bunker et al., submitted)
z=1 arc de-lensed
Mark Swinbank, Joanna Smith, Richard Bower,
Andrew Bunker et al
[OII]3727Å velocity map
HST/WFPC (B,R,I) F450W, F606W, F814W
sky (lensed) de-lensed
Galaxy Kinematics at High Redshift:
Why do we care?
- For disk galaxies, velocity at flat part of rotation curve correlates with the stellar mass of the galaxy (I- or K-band) - the Tully Fisher relation-How does this scaling relation evolve with time?- In "classical" model, dark halo forms first, and disk forms later: M/L decreases with time.-So circular velocity at a fixed stellar mass less in the past- BUT in hierarchical assembly, make galaxies through mergers, so stellar mass vs. circular velocity follows same relation over a wide range of redshifts- Can test this through rotation curves of z~1 galaxies- Use rest-optical lines redshifted into near-infrared- IFUs ideal - no uncertainty of slit axis vs. galaxy axis
CIRPASS refereed Publications "Spectroscopic Gravitational Lensing and Limits on the Dark Matter Substructure in Q2237+0305" R.B. Metcalf, L.A. Moustakas, A.J. Bunker & I.R. Parry ApJ (astro-ph/0309738)
"Extragalactic integral field spectroscopy on Gemini" A. Bunker, J. Smith, I. Parry, R. Sharp, A. Dean, G. Gilmore, R. Bower, A.M. Swinbank, R. Davies, R.B. Metcalf & R. de Grijs (astro-ph/0401002)
"CIRPASS near-IR integral field spectroscopy of massive star clusters in the starburst galaxy NGC1140" R. de Grijs, L.J. Smith, A. Bunker, R. Sharp, J. Gallagher, P. Anders, A. Lancon, R. O'Connell & I. Parry; MNRAS (astro-ph/0404422)
"The Tully-Fisher Relation at z~1 from CIRPASS near-IR IFU H-alpha spectroscopy" J. Smith, A. Bunker, N. Vogt et al. MNRAS 2004
Seeing fluorescence from neutral hydrogen
5"
200Å
20"
zem=4.487
Spatially Extended Ly- Emission
z=4.5 QSO illuminating its protogalaxy
Extended Ly- , narrow (FWHM~1000km/s)
Central QSO (solid line)
broad Ly-Extended narrow Ly- (dashed
line),no continuum
Recombination line probably powered by reprocessed QSO UV flux rather than by local star formation.
The HI cloud of the host galaxy is
~>35kpc/h70 (=0.3)
SPH simulations, distribution of neutral gas at z~3 (from Katz et al. and Rauch, Haehnelt & Steinmetz).
Left box is 22Mpc comoving, 15arcmin; right zoomed x10
DAZLE - Dark Ages 'z' Lyman-alpha Explorer (IoA - Richard McMahon, Ian Parry; AAO - Joss
Bland-Hawthorne
"Lyman break
technique" - sharp
drop in flux at
below Ly-.
Steidel et al. have
>1000 z~3 objects,
"drop" in U-band.
Pushing to higher
redshift- Finding
Lyman break galaxies
at z~6 : using i-drops.
The Star Formation
History of the Univese
Bunker, Stanway, z=5.8
Ellis, McMahon
& McCarthy (2003)
Keck/DEIMOS
spectral follow-up
& confirmation
I-drops in the Chandra Deep
Field South with HST/ACS
Elizabeth Stanway, Andrew
Bunker, Richard McMahon
2003 (MNRAS)
Galaxies at z~6 are small - barely resolved by HST. E-
ELT diffraction limit ~0.01” (~50-100pc). See individual HII regions?
What is JWST?● 6.55 m deployable primary
● Diffraction-limited at 2 µm
● Wavelength range 0.6-28 µm
● Passively cooled to <50 K
● Zodiacal-limited below 10 µm
● Sun-Earth L2 orbit
● 4 instruments
– 0.6-5 µm wide field camera (NIRCam)
– 1-5 µm multiobject spectrometer (NIRSpec)
– 5-28 µm camera/spectrometer (MIRI)
– 0.8-5 µm guider camera (FGS/TF)
● 5 year lifetime, 10 year goal
● 2014 launch
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
NASA/ESA/CSA - JWST● NIRSpec
– ESA near-IR MOS to 5um, 3’x3’
● NIRCAM - 3’x3’ imager <5um
● FGS (Canada) - has tunable
1% narrow-band NIR filters
in
● MIRI - mid-infrared
Europe/US
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
(closely similar to HST model…)
Absorption lines at z>5 - a single v. bright Lyman
break z=5.5 galaxy, Dow-Hygelund et al (2005),
AB=23-24, VLT spectrum (22 hours), R~3000; S/N=3-10 at
R=1000,2700 in 1000sec NIRSpec
For I-drops (z~6) would only get ~1 per NIRSpec field bright enough for S/N~3-10 in continuum in 1000sec for abs line
studies
Does AO Help you?
-If Ly-alpha is compact, AO will boost point-source sensitivity-- Unclear if this will be the case - extended Ly-alpha haloes known, and expected through resonant scattering (see the far edge of the ionized bubble)
--For morphological analysis, unclear that high-tech ELT AO is better than a poorer but better-quantified PSF (e.g. from space)--If you can’t quantify where 10-20% of the light goes from a centrally-condensed core, that’s the difference between a disk and bulge morphology when fitting Sersic index--Even worse when looking for QSO host galaxies…
Conclusions-- 3D IFU spectroscopy at high redshift is (finally) realising its potential, but still small sample sizes--Important as a probe of galaxy kinematics, and spatially-resolved maps of stellar populations, metallicity-- Trace the evolution of the assembly of stellar mass--Explore the nature of gravitational lenses (dark matter)-- Explore the nature of the galaxies responsible for QSO absorption lines--In future might see fluorescence of the HI gas--Compact galaxies at high-z: need AO on ELTs to get real IFU benefit