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Direct-Detection Spectroscopy at the CSO with Z-Spec and ZEUS. Probing galaxies near and far with two new bolometers-based grating spectrometers Matt Bradford with input from Gordon Stacey August 4, 2008. Dominant gas coolants are in the far-IR / submm Redshifted to the submm / mm.
Probing galaxies near and far with
two new bolometers-based grating spectrometers
Matt Bradford with input from Gordon Stacey
August 4, 2008
CSO @ z=0
CSO @ z=1.2
CSO @ z=2.6
CSO @ z=4.4
SED courtesy A. Blain
Direct-Detection SpectroscopyA survey capability which complements the high spatial and spectral resolution of interferometers (CARMA / ALMA)
The Redshift (z) and Early Universe Spectrometer
Stacey et al. (Cornell) w/ GSFC, NIST
Glenn (U. Colorado); Bradford, Bock, Zmuidzinas, (Caltech), Aguirre (CU-> Penn), Matsuhara (ISAS)
Both with sensitivity very close to fundamental limits at the CSO
BP Filter Wheel
LP Filter 2
4He Cold Finger
LP Filter 1
Quartz & LP Filter 1
Dual Stage 3He Refrigerator
ZEUS observations of NGC 253: First Extragalactic Detection of 13CO(6-5)
likely due to that X-rays from the starburst or the decay of micro-turbulence within clouds must dominate the heating.
Hailey-Dunsheath et al. in prep.
Arp 220 CO(6-5)
IRAS 17208 CO(6-5)
NGC 6240 CO(6-5)
NGC 6240 CO(8-7)
NGC 6240 [CI] (2-1) & CO (7-6)
Nikola et al. in prep.
Hailey-Dunsheath et al. 2008
H.A. Rowland, 1883, Phil. Mag 16
K.A. McGreer, 1996, IEEE Phot. Tech. 8
CSO, Mauna Kea
3He RADIATION SHIELD
Lieko Earle (Colorado),
Bret Naylor (Caltech)
Lieko Earle, U. Colorado Ph.D. ‘08
3.5 hours telescope time
19 ID’d transitions > 3s
+4 unID’d as of yet.
B. Naylor et al., ApJ in prep.
Compile all transitions, use RADEX to model excitation & transfer in the lines
-> Generate Bayesian likelihoods
SO2Combine in a
-> evidence of cold, dense gas component
-> the material actually forming the stars?
Z-Spec Survey Program
Funded by NSF AAG
(Aguirre et al. U. Penn)
ZEUS upgrade to ZEUS-2
Funded by NSF MRI
[CII]/far-IR continuum luminosity ratio vs. density for various G (from Kaufman 1999).[CII]/far-IR Constrains Starburst Extent
L[CIII] ~ 2.5 1010 L
Lfar-IR ~ 3.2 1013 L
30% of [CII] from ionized medium
R =5.5 10-4
G ~ 2000
far-IR = L/(4D2) = 14
DL~ 9.2 Gpc
= IR/(G 2) = 3.5 x 10-3
= beam = 0.083(”)2
d ~ 0.32” 2.75 kpc
Galaxy-wide starburst supports the contention that hyper-luminous systems may be giant elliptical galaxies in formation (unlike local ULIRGs)
Measured with long-path FTS
(~100 MHz resolution)
Observed noise white with atmospheric 1/f
Relative to an imaging system, fundamental noise levels are lower, but some systematic aspects are easier.
Chopping -> response to a single frequency
Narrow spectrometer bandwidth helps
NEFGaussian noise ~ sqrt()
Scaling consistent with e.g. Bolocam observations
Clear scaling with , very close to photon background limit
Blue -> achieved at =0, 0.1, 0.2
Black -> simple model for Z-Spec at CSO
Det, amplifier, & internal load NEP: 6.4e-18 W/sqrt(Hz)
(not tracking detector parameters in detail)
measured instrument trans (~0.25)
Aperture efficiency per taper + Ruze (60-70%)
measured chop duty cycle (65%)
photon noise from sky + telescope the most important term
-> additional factor of 1.2
James Aguirre -> U. Penn
Recent Caltech Ph.D.
Colorado Ph.D. student
(finishing Spring 08)
[ Line fluxes in Jy km/s, HCN / CO ratio corrected for to TMB ]
Line fluxes SNR 4 - 20
Not finding overluminous HNC / HCN 3-2 ratio as per Aalto, Cernicharo.
will follow-up further at CSO.