Line Detection Rates for Next Generation IR/Submm Spectroscopic
Surveys Eric J. Murphy BLISS/X-Spec Science teams
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Meet Dylan
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Why mid-/far-IR Spectroscopy: BLISS? Many bright atomic
fine-structure + access to H 2 lines and PAH features Many bright
atomic fine-structure + access to H 2 lines and PAH features
1Cosmic Star Formation History SFR, gas density, etc. 2Cosmic Rise
of Heavy Elements PAH emission at z ~6 3Black Hole Birth Extreme
species e.g., [NeV] and high-J CO lines 4Gas in Forming Planetary
Systems Gas cools through FIR atomic O and C transitions --
gas-disk lifetimes BLISS band at z=2 BLISS band at z=4 Circinus
Galaxy ISO SWS+LWS Egami et al 2006, Spitzer IRS Detectable at
z~8-10 with BLISS!
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Why Submm Spectroscopy: X-Spec Many bright atomic fine-
structure and molecular rotational transitions detectable. Many
bright atomic fine- structure and molecular rotational transitions
detectable. Spectroscopic redshifts and interstellar gas conditions
from galaxies in the early universe (i.e., z > 6) Spectroscopic
redshifts and interstellar gas conditions from galaxies in the
early universe (i.e., z > 6) e.g., z=6.42 Walter et al. 2009).
e.g., z=6.42 Walter et al. 2009). Much faster (~30x) than ALMA for
survey work! Much faster (~30x) than ALMA for survey work! Z-spec
Spectra from Bradford+ (2011/2010) z=2.56
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BLISS/SPICA Specs. ParameterGoalRequirementScientific /
Technical Driver Primary Aperture 3.15 m Telescope Temperature5.5 K
~ x10,000 lower background than Herschel (T ~ 80 K) Line
sensitivity (3 , 1h) 1 x 10 -20 W m -2 2 x 10 -20 W m - 2 Observing
galaxies from the first billion years of the Universe to the
present day. Observing galaxies from the first billion years of the
Universe to the present day. Spectral resolving power ( ) 700300
Avoiding line confusion with multiple sources along the line of
sight. Spectral coverage 35 433 m Simultaneously covered in 6 bands
Completely fill spectral gap between JWST / SPICA mid-IR &
ALMA. Number of beams2 (source + reference) Redundancy against a
single detector failure & improved sensitivity/sampling.
Detector sensitivity (NEP)5x10 -20 W/Hz -1/2 1x10 -19 W/Hz - 1/2
Supports astronomical sensitivity requirement, close to natural
photon background. Instrument temperature50 mK60 mKSupports
detector sensitivity. SubsystemApproachHeritage TES bolometer array
systemJPL dual TES w/ Ti, AlBICEP2, SPIDER (balloon) Low-NEP TES
bolometer60mK MoCu bilayer on mesh absorberBLISS development
program Detector cold readoutNIST time-domain SQUID MUXBICEP2,
SPIDER, SCUBA2, ACT, etc Short-wavelength
spectrometerCross-dispersed echelle gratingSpitzer IRS (flight)
Long-wavelength spectrometerWaFIRS waveguide gratingZ-Spec
Instrument cooler50 mK adiabatic demagnetization (ADR)Z-Spec, SPIFI
Chopping mirrorLow-dissipation 4K mechanismHerschel HIFI
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First Light Instrument for CCAT First Light Instrument for CCAT
Primary Mirror: 25m Primary Mirror: 25m chopping Secondary? B1: 575
945 m B2: 965 1535 m chopping Secondary? B1: 575 945 m B2: 965 1535
m MDLF (3 , 1hr): 0.72 7.2 x 10 -20 W m -2 MDLF (3 , 1hr): 0.72 7.2
x 10 -20 W m -2 SuperSpec chip with MKIDs SuperSpec chip with MKIDs
Simpler readout architecture than TES bolometers Simpler readout
architecture than TES bolometers 100-1000 detectors per wire vs.
5-20 100-1000 detectors per wire vs. 5-20 Two potential
implementations: Two potential implementations: Direct Imaging
Spectrometer Direct Imaging Spectrometer Steered Beam Multi-object
Spectrometer Steered Beam Multi-object Spectrometer X-Spec/CCAT
Specs.
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BLISS/X-Spec Sensitivities Put into Context Matt Bradford
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Is confusion going to be an issue? Constructing Line Count
Models Galaxy Number Count Models: N ( z, L IR ) Galaxy Number
Count Models: N ( z, L IR ) E.g., Chary & Pope (2012) E.g.,
Chary & Pope (2012) Uses the deepest 24 m data & Spec- z s
from GOODS Uses the deepest 24 m data & Spec- z s from GOODS
Constrained by the Cosmic IR Background Constrained by the Cosmic
IR Background Consistent with Herschel observations Consistent with
Herschel observations Does not take clustering into account Does
not take clustering into account Empirical Line Prescriptions (31
lines included) Empirical Line Prescriptions (31 lines included) 15
mid-/far-IR lines: Spinoglio et al. (2012) 15 mid-/far-IR lines:
Spinoglio et al. (2012) 16 CO & other submm line: Visbal &
Loeb (2010) 16 CO & other submm line: Visbal & Loeb
(2010)
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Integral Line Counts: BLISS/SPICA More lines at longer
wavelengths Naturally, since beam increases w/ Also, more species
available (8 to 16 between 50 and 350 m) 50 and 350 m) At 250 m,
one line per 75 beams detected (5 ) with > 1.5 x 10 -20 W m -2
(5 ) with > 1.5 x 10 -20 W m -2 1 hr
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Integral Line Counts: X-Spec/CCAT More lines at longer
wavelengths Naturally, since beam increases w/ Number of available
species ~17 at all At 1.3mm, 70 x 1hr pointings (300 beams/pt) to
detect a single line (5 ) with >1.5 x 10 -20 W m -2 detect a
single line (5 ) with >1.5 x 10 -20 W m -2 1 hr 70 hr
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So, even with BLISS, confusion is not an issue But can we
extract lines from spectra? Assuming two off nod positions
Intrinsic Source Spectrum Blank Field Spectrum 10 Examples Confused
Spectra Monte-Carlo number counts between NGC520, Mrk231, and
Arp220 Mock Observation of NGC520 at z =4 scaled to L IR 2x10 12
L
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Findings & Remaining Issues BLISS: BLISS: Line Confusion
does not seem to be an issue Line Confusion does not seem to be an
issue How well can identify & recover line fluxes in spectra?
How well can identify & recover line fluxes in spectra?
Quantify how the continuum shapes of sources are affected by
intervening sources (needed for M d, T d, L d ). Quantify how the
continuum shapes of sources are affected by intervening sources
(needed for M d, T d, L d ). Is R =400 too course spectral
resolution? Is R =400 too course spectral resolution? X-Spec X-Spec
Many pointings to measure1 line even with 300 beams Many pointings
to measure1 line even with 300 beams Steerable system or a integral
field unit? Steerable system or a integral field unit?
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BLISS Specs. ParameterGoalRequirementScientific / Technical
Driver Line sensitivity (3 , 1h) 1 x 10 -20 W m -2 2 x 10 -20 W m
-2 Observing galaxies from the first billion years of the Universe
to the present day. Spectral resolving power ( ) 700300 Avoiding
line confusion with multiple sources along the line of sight.
Spectral coverage35-433 microns in 6 bands Completely fill spectral
gap between JWST / SPICA mid-IR & ALMA. Number of beams2
(source + reference) Dual beam provides redundancy against a single
detector failure producing a hole in spectral coverage, and
improved sensitivity and sampling. Detector format42242816Full
coverage across the BLISS band in two fields. Detector
sensitivity5x10 -20 W/Hz -1/2 1x10 -19 W/Hz -1/2 Supports
astronomical sensitivity requirement, close to natural photon
background. Instrument temperature50 mK60 mKSupports detector
sensitivity. SubsystemApproachHeritageTRL TES bolometer array
systemJPL dual TES w/ Ti, AlBICEP2, SPIDER (balloon)6 Low-NEP TES
bolometer60mK MoCu bilayer on mesh absorberBLISS development
program3-4 Detector cold readoutNIST time-domain SQUID MUXBICEP2,
SPIDER, SCUBA2, ACT, etc6 Warm electronicsMulti-channel electronics
(MCE).same.6 Short-wavelength spectrometerCross-dispersed echelle
gratingSpitzer IRS (flight)7 Long-wavelength spectrometerWaFIRS
waveguide gratingZ-Spec6 Instrument cooler 50 mK adiabatic
demagnetization (ADR) Z-Spec, SPIFI6 Intercept cooler300 mK
continuous He sorptionHerschel SPIRE7 Chopping
mirrorLow-dissipation 4K mechanismHerschel HIFI
