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 / submmRedshifted to the submm / mm

SED courtesy A. Blain CO

C0

N+

C+

O0

O++

CSO @ z=0

CSO @ z=1.2

CSO @ z=2.6

CSO @ z=4.4

The World’s Only Submillimeter Grating Spectrometers

ZEUSThe Redshift (z) and Early Universe Spectrometer

Stacey et al. (Cornell) w/ GSFC, NIST Short submm windows: 350mm, 450mm Slit-fed echelle grating, 4th and 5th order Resolving power ~1200 (300 km/s) 20 GHz (~2-4%) instantaneous bandwidth 1x32 bolometer array, but TES upgrade underway

Z-SpecGlenn (U. Colorado); Bradford, Bock, Zmuidzinas,

(Caltech), Aguirre (CU-> Penn), Matsuhara (ISAS) 1 mm window: 195-310 GHz Single beam w/ new waveguide grating architecture Resolving power ~300 (1000 km/s) 115 GHz instantaneous bandwidth 160 individually-mounted Ge-sensed bolometers

Both with sensitivity very close to fundamental limits at the CSO

Primary Scientific Objectives Embedded energy sources and conditions of star forming gas in

local-universe infrared-bright galaxies (LIRGS and ULIRGS).

Interstellar medium conditions and spatial extent of star formation extent in the era of peak star-formation history (z=0.5 to 2) and prior.

Evolutionary history of energy release via unbiased redshift surveys.

ZEUS

J=6->5 and 7->6 in both 12CO and 13CO and [CI] J=2->1 constrain the mass and energy budget of the warm molecular gas.

Z-Spec

Complete 1-mm spectrum includes multiple high-critical-density species: CN, CS, HCN, HNC, HCO+. A rapid census of the dense molecular gas.

ZEUS

C+ at z=1--1.2 and 1.8--2. C+ to dust continuum ratio measures the UV field intensity, constrains the extent of the starburst.

Access [OI], [NII], [OIII] at the highest redshifts.

Z-Spec

Full band provides at least 2 CO transitions to measure redshift as well as temperature, density, and mass of the molecular gas.

Unexplored rest-frame short-submm.

C+, other fine-structure transitions accessible beyond z=6.

ZEUS on the CSO Mounted on the left Nasmyth focus Can be co-mounted with both Z-Spec and Bolocam First light in 2006 Steve Hailey-Dunsheath PH.D. (Cornell 2008) Thanks to NSF and NASA support:

NSF ATI: 01-04, 04-07, 07-10 NSF MRI for ZEUS-2 NASA GSRP

ZEUS Observations of LIRGs & ULIRGs Pre-ZEUS: 1 ULIRG in CO 6-5

(Mrk 231, Papadopoulos et al. 07)

ZEUS has observed ~19 LIRGs and ULIRGs to date Most in CO (6-5) Some also in CO (7-6) & [CI]

(2-1) or CO (8-7) Fractional mid-J CO luminosity

decreases in the most powerful sources (as with C+).

-> More concentrated systems than the less-luminous starbursts.

Nikola et al. in prep.

-0.05

0

0.05

0.1

0.15

0.2

3000 4000 5000 6000 7000 -0.010

0.000

0.010

0.020

0.030

4000 5000 6000 7000

-0.04

0.00

0.04

0.08

0.12

0.16

5200 6200 7200 8200

Arp 220 CO(6-5)

NGC 6240 CO(6-5)

IRAS 18293CO(6-5)

T MB(K

)

-0.025

0

0.025

0.05

0.075

11000 12000 13000 14000

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

5700 6700 7700

VLSR(km/s) VLSR(km/s)

IRAS 17208 CO(6-5)

NGC 6240 [CI] (2-1) & CO (7-6)

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

5500 7500

vLSR [km/s]

TM

B [K

]

NGC 6240 CO(8-7)

Arp 220

NGC 6240

Zw049M 82

Arp 299

IRAS17208

Mrk 231

L>1012

L>1011

L<1011

0.0

1.0

2.0

3.0

4.0

9 10 11 12 13

log(LFIR/LSUN)

CO

(6-5

)/F

(60 μ

m)

ZEUS High-Redshift Example: [CII] from MIPS J142824.0 +352619

Identified as red object in MIPS Bootes field (Borys et al. 2006)

Integrated far-IR SED indicates Lfar-IR ~ 3.21013 L

Likely a mildly lensed super-starburst galaxy

ZEUS/CSO detection in April 2008 -- 1.5 hours of good (but not great) weather (225 GHz ~ 0.05 to 0.06) I[CII] ~ 6 K-km/sec Fline ~ 9.0 10-18 W m-2

L[CII] ~ 2.5 1010 L

CII / far-IR ratio much greater than in local ULIRGs. Conclude that starburst is 2-3 kpc in extent – “galaxy wide starburst”

Hailey-Dunsheath et al. 2008

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

-1000 -500 0 500 1000 1500

TM

B(m

K)

VLSR w.r.t. z = 1.3249

MIPS J142824.0+352619

[CII] at z = 1.3249

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

-1000 -500 0 500 1000 1500

TM

B(m

K)

VLSR w.r.t. z = 1.3249

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

-1000 -500 0 500 1000 1500

TM

B(m

K)

VLSR w.r.t. z = 1.3249

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

-1000 -500 0 500 1000 1500

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

MIPS J142824.0+352619 [CII] @ z=1.3249

-10

-5

0

5

10

15

20

1828.51044.5260.5-523.5

ZEUS/CSO

-1000 -500 0 500 1000 1500-1000 -500 0 500 1000 1500

TM

B(m

K)

VLSR w.r.t. z = 1.3249

MIPS J142824.0+352619

[CII] at z = 1.3249

Z-Spec: A New Ultracompact Waveguide Grating

Propagation confined in parallel-plate waveguide 2-D Geometry Stray light eliminated

Curved grating diffracts and focuses Efficient use of space No additional optical elements

Custom “stigmatic” grating design possible at long wavelengths

K.A. McGreer, 1996, IEEE Phot. Tech. 8H.A. Rowland, 1883, Phil. Mag 16

curved grating in parallel plate waveguide

Z-Spec Layout

FRIDGE

Focal ARC

GRATING ARC

ADR

INPUTFEEDHORN

3He RADIATION SHIELD

Individually mountedSiN bolometers

CSO, Mauna Kea

Z-Spec graduate students @ 13,400 ft Lieko Earle (Colorado), Bret Naylor (Caltech)

Z-Spec Support• NSF career (Glenn) + CSO• NASA SARA• JPL DRDF, Caltech Pres. Fund + Millikan• U. Colorado + Research Corp

Z-Spec 1 mm survey of NGC 253Lieko Earle, U. Colorado Ph.D. ‘08

3.5 hours telescope time>15 ID’d transitions > 3s+2-4 unID’d as of yet.

Z-Spec Spectra from the CSO

Z-Spec Spectra from the CSO

Molecular Gas in Local-Universe Galaxies, ex. M82 B. Naylor et al., ApJ in prep.

HCO+

Compile all transitions, use RADEX to model excitation & transfer in the lines-> Generate Bayesian likelihoods

NE

SW

Cen

Also include:CSHNCSO2

Combine in a single model:-> evidence of cold, dense gas component -> the material actually forming the stars?

7.9 hours total time

Weiss et al. continuum estimates

Z-Spec

Barvainis et al., 1997

Weiss et al., 2003

APM 08279+5255 at z=3.91F

lux

Den

sity

[J

y]

322 mm 200 mmRest

APM 08279+5255 at z=3.91F

lux

Den

sity

[J

y]

322 mm 200 mmRest

A reminder: Arp 220 in the far-IRISO LWS, Gonzalez-Alfonso et al. 04

APM 08279+5255 at z=3.91F

lux

Den

sity

[J

y]

322 mm 200 mmRest

Plans for the next cycleZEUS & Z-Spec instrument teams funded

ZEUS upgrade to ZEUS-2Funded by NSF MRI

Incorporating (3) NIST 2-d TES bolometer arrays which share the focal plane and can operate simultaneously: 10 x 24 at 200 mm 9 x 40 at 350-450 mm 5 x 12 at 650 mm

Up to 5 lines simultaneously (in extended sources)

Some imaging capability (9-10 beams)

Closed cycle refrigerators

Z-Spec Survey ProgramFunded by NSF AAG

(Aguirre et al. U. Penn)

Dense gas in Local-Universe dense molecular gas surveys. 50 galaxies, 8 hours per

Mid-J CO + spectral discovery in high-z objects with and without prior redshifts. 20 galaxies, 24 hours per

Excellent use of low-frequency time at CSO. Baseline 300 hours per year,

could be more. Helium recycler under study

to reduce cryogen costs.

Backup material

Direct-Detection SpectroscopyA survey capability which complements the high spatial and spectral

resolution of interferometers (CARMA / ALMA)

Submillimeter is the region of overlap between coherent (heterodyne) and incoherent (direct-detection) techniques for astrophysics.

Coherent approaches have yielded much of the spectroscopic work to date. High spectral resolution required for Galactic cores. Large bandwidths not essential for Galactic sources or nearby galaxies. SIS mixers near quantum limit, (also near background limit at 1 mm). Until recently, direct detectors neither sufficiently sensitive, nor sufficiently arrayed to

be compelling. Direct-detection spectrometers (gratings and Fabry-Perots) for long wavelengths are

large and expensive.

Direct-detection submillimeter spectrometers are now compelling Submillimeter spectroscopy coming of age as an extragalactic probe. Spectral resolution greater than few x 1000 not required. Direct detectors are now readily background-limited, and are undergoing a revolution

in format (driven by cameras). Large fractional bandwidth presents a new discovery space for measuring

redshifts and multiple lines. Multi-object capability a natural progression with a direct-detection system.

Grant Numbers

ZEUS NSF Grant AST-0096881 (Advanced Technology and Instrumentation 2001-

2004) NSF Grant AST-0352855 (Advanced Technology and Instrumentation 2004-

2007) NSF Grant AST-0705256 (Advanced Technology and Instrumentation 2007-

2010) NASA Grant NGT5-50470 (NASA GSRP 2003-2006) NSF Grant AST-0722220 (Major Research Instrumentation 2007-2010)

Z-Spec NSF CAREER grant (Glenn): AST0239370 NASA SARA grants: NAG5-11911 JPL DRDF Caltech President's Fund Caltech Millikan Fellowship Research Corporation Innovation Award: RI-0928 University of Colorado

35 cm long R2 echelle grating blazed for 5th order @ 359 m There is a series of a scatter, quartz, 2 long pass, and a bandpass filter in series to achieve

dark performance (Cardiff U.) Total optical efficiency: ~ 30%, or 15% including bolometer DQE

Dual Stage 3He

Refrigerator

4He cryostat

M5: Primary

Grating

Detector Array

Scatter Filter

LP Filter 1

LP Filter 2

BP Filter Wheel

M1

M2

M3

M4

M6

4He Cold

Finger

Entrance Beamf/12

Grating

Quartz & LP Filter 1

Refrigerator

ZEUS: Optical Path

ZEUS observations of NGC 253: First Extragalactic Detection of 13CO(6-5)

Line is bright ~ 10% that of the 12CO(6-5) line indicating optically thick emission in the main line.

Also re-observed (and mapped) the CO(7-6) line to constrain LVG models

35 to 55% of the molecular ISM is warm and dense: T~ 120 K, n~104 cm-3

Heating this much gas is difficult:likely due to that X-rays from the starburst or the decay of micro-turbulence within clouds must dominate the heating.

These processes are powered by the starburst -> the starburst is self-regulating.

Hailey-Dunsheath et al. in prep.

12CO(6-5)

13CO(6-5)10

TM

B(K

)

vLSR(km/s)

TM

B(K

)

vLSR(km/s)

CO(7-6)

[CI] (2-1)

12CO(6-5)

13CO(6-5)10

12CO(6-5)

13CO(6-5)10

TM

B(K

)

vLSR(km/s)

TM

B(K

)

vLSR(km/s)

CO(7-6)

[CI] (2-1)

ZEUS/CSO

[CI] (2-1) line only 1000 km/s to the blue and always within ZEUS band.

[CII]/far-IR Constrains Starburst Extent

L[CIII] ~ 2.5 1010 L

Lfar-IR ~ 3.2 1013 L

30% of [CII] from ionized mediumR = 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

Starlight that contributes to but not G

[CII]/far-IR continuum luminosity ratio vs. density for various G (from Kaufman 1999).

+3600- 700

Galaxy-wide starburst supports the contention that hyper-luminous systems may be giant elliptical

galaxies in formation (unlike local ULIRGs)

Range: 185--305 GHz

• Resolving power: 250--400

(Not over sampled)(750 < v < 1200 km/s)

• Complete coverage from channel to channel -> no gaps

Z-Spec channel spectral responseMeasured with long-path FTS(~100 MHz resolution)

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 helpsNEFsky ~ NEFGaussian noise ~ sqrt()

Scaling consistent with e.g. Bolocam observations

Z-Spec SensitivityObserved noise white with atmospheric 1/f

500

300

Blue -> achieved at =0, 0.1, 0.2Black -> 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

Z-Spec SensitivityClear scaling with , very close to photon background limit

=0

=0.1

=0.2

Bret NaylorRecent Caltech Ph.D.

James Aguirre -> U. PennJansky FellowColorado, NRAO

Lieko EarleColorado Ph.D. student(finishing Spring 08)

Z-Spec labor force

ULIRG Survey Preliminary Results

Galaxy cz Log L CO CN HCN HNC HCO+ HCN/CO HNC/HCN HCO+/HCN

M82 250 10.8 16803 749 202 169 799 0.009 0.84 3.95

NGC 1068 1137 11.5 6590 432 317 91 219 0.036 0.29 0.69

Arp 220 5434 12.0 1418 76 275 243 81 0.144 0.88 0.29NGC6240 7340 11.8 1596 53 68 <20 88 0.031 <0.29 1.31Mrk273 11326 12.1 342 47 41 20 19 0.089 0.48 0.47NGC4418 11782 11.7 367 47 106 42 30 0.215 0.40 0.28UGC5101 11809 12.0 301 22 22 19 13 0.055 0.84 0.57Mrk231 12650 12.2 536 76 54 41 44 0.075 0.76 0.81IRAS 17208 12834 12.4 570 29 47 47 25 0.061 0.99 0.53

Starburst

Seyferts

ULIRGS

Not finding overluminous HNC / HCN 3-2 ratio as per Aalto, Cernicharo.will follow-up further at CSO.

[ Line fluxes in Jy km/s, HCN / CO ratio corrected for to TMB ]Line fluxes SNR 4 - 20

Nearby Seyfert NGC 1068