zeus/cso observations of far-infrared fine structure … fine structure lines: diagnostics of star...
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ZEUS/CSO Observations of Far-Infrared Fine Structure Lines: Diagnostics of Star
Formation in the Early Universe
Gordon Stacey Cornell University
S. Hailey-Dunsheath, T. Nikola, C. Ferkinhoff, S.C. Parshley, D. Benford, J.G. Staguhn, C. E. Tucker, & N. Fiolet
1
Far-IR Fine Structure Lines Most abundant elements are O, C, N Species with 1,2,4 or 5 equivalent p electrons will have ground state
terms split into fine-structure levels For O, C, N they lie in the far-IR where extinction is not an issue
Collisionally excited / optically thin ⇒ cool the gas – trace its physical conditions
Reveal the strength and hardness of ambient UV fields.
2p: O++; N+; C0
0
3P2
3P0
3P1
[OIII] 51.8 µm
[OIII] 88.3 µm
442
163
2P3/2
2P1/2 0
1p: O+++; N++; C+
[OIV] 25.9 µm
557
Ener
gy A
bove
Gro
und
(K)
[NII] 121.9 µm
[NII] 205.2 µm
189
70
[CI] 370.4 µm
[CI] 609.1 µm
63
39
4p: O0
3P0
3P2
3P1
327
228 [OI] 63.18 µm
[OI] 145.5 µm
[NIII] 57.4 µm
251 91
[CII] 157.7 µm
FP = 11.3 eV FP = 0, IP = 13.62
Utility: Ionized Gas Regions Density tracers
Far-IR fine-structure lines have Einstein A coefficients ∝ ν3 Collision rate coefficients are typically ~ qul ~ 3×10-8 cm3/sec for
e- impact excitation (and qul ~ 2×10-10 H/H2 impact excitation) ∴ since ncrit ~ A/qul we have ncrit ∝ ν3
Furthermore the emitting levels lie far below gas temperatures ⇒ line ratios T-insensitive probes of gas density
0
3P2
3P0
3P1
[OIII] 51.8 µm
[OIII] 88.3 µm
442
163
[NII] 121.9 µm
[NII] 205.2 µm
189
70 ncrit ~ 48 cm-3
ncrit ~ 310 cm-3
Utility: Ionized Gas Regions Hardness of the ambient radiation field
Within an HII region, the relative abundance of the ionization states of an element depend on the hardness of the local interstellar radiation field. For example:
O+++ (54.9 eV), O++ (35.1 eV), O0 (<13.6 eV)
N++(29.6 eV), N+ (14.5 eV)
AGN
O8
O7.5
B0
Neutral ISM
Line
Rat
io
Teff (1000 K)
Line ratios between ionization states determine Teff
B2V O7.5V
Neutral Gas Lines
[CII] 158 µm: 11.3 eV to form C+ ⇒ Arises from both neutral and ionized gas clouds
Level is only 91 K above ground ⇒ Dominant coolant of atomic ISM
Warm neutral medium (WNM): T ~ 5,000 K, n ~ 0.5 cm-3 Cold neutral medium (CNM): T ~ 100 K, n ~ 30 cm-3
Important coolant for diffuse ionized clouds Warm ionized medium (WIM): T ~ 8,000 K, n ~ 0.5 cm-3
ncrit (neutrals) ~ 2800 cm-3 ⇒ also might expect [CII] to be an important coolant for photodissociated surfaces of molecular clouds:
n ~ 300 cm-3 5
[CII] and [OI] O0 has same ionization potential as H ⇒ only found in
neutral gas regions Two level system ⇒ probes n ~ few 103 to 106 cm-3
[OI] 63 a bit problematic due to optical depth effects (long) known to be optically thickish in emission (Stacey
et al. 1983) Known to be self-absorbed by lower excitation gas (e.g.
Poglitsch et al. 1996) High ncrit ⇒ emission traces dense PDRs
[OI] 146 µm line a better probe than the 63 µm line? Near [CII] where line ratio traces physical conditions ⇒
can detect with same system at same z “Only” 6 times weaker than [CII]
6
Another Problem…
[CII] line is ubiquitous – how to separate out fractions from PDRs WNM, CNM, and WIM? Has been shown locally
that WNM and CNM contributions are small relative to PDRs – not enough column at these modest densities.
However, collisions with e- stronger ⇒ can get substantial fraction from WIM
7
A solution: [NII] Studies [NII] found only in HII regions Formation energy of N++ and
C++ similar ⇒ N+ and C+ found in similar ionization zones
[NII] 205 µm and [CII] line have same ncrit for e- impact excitation ⇒ line intensity ratio only dependent on relative C/N abundance ratio
Carina: observed ratio ~ 9.1, ionized ratio ~ 2.4 ⇒ 75% from PDRs
8
Carina: Oberst et al. 2006
Neutral Gas Emission 9
Photodissociation Regions
Molecular cloud collapses, forming stars.
Ionized Hydrogen (HII) regions surrounding newly formed stars.
Photodissociation regions form where far-UV (6-13.6 eV) photons impinge on neutral clouds
10
Structure of the PDR FUV flux onto neutral clouds Thin HII/HI interface absorbs
the Lyman continuum flux Structure depends on G/n:
G0 [1.6×10-3 erg cm-2 s-1] ~ 1 (local) to 105 (Orion)
n ~ 0.5 (WNM); 30 (CNM); 102.5-106 (GMCs)
HI layer to AV~1-2: H2 interface C+ to AV ~ 3 determined by
dust extinction of FUV photons C+/C/CO transition O to AV ~ 10 Heating: photo-electric effect Cooling: fine-structure lines
[CII] and [OI]
Hollenbach and Tielens, Rev. Mod. Physics 71, 173 (1999)
PDRs are Important
By Mass GMC PDRs
Milky Way ~ 10% Starbursters ~ 50%
Atomic Gas ~ 50% Cold neutral medium
(aka Atomic Clouds) Warm neutral medium
By Energetics [CII] line often brightest
single line from star forming galaxies
[OI] similar Also important
[SiII] 34.8 µm H2 rotational [CI] 370 and 609 µm CO rotational lines
FIR continuum also largely arises from PDRs 11
158 µm [CII] in Star Forming Galaxies [CII] brightest line in most star
forming galaxies with a luminosity ratio R ≡ L[CII]/LFIR ~ 0.1% to 1%
Bi-modal [CII]/CO(1-0) correlation [CII]/CO(1-0) ~ 4100 for starburst
galaxies and Galactic starformation regions
[CII]/CO(1-0) ~ 1200 for non-starburst galaxies and Galactic GMCs
Emission interpreted within PDR paradigm
12
[CII]/CO/FIR all arise from PDRs on the surfaces of molecular clouds exposed to far-UV radiation from stars
G0 ~ 50-2000, n~103-104 cm-3: Lower G0 appropriate for non-starburst galaxies
Stacey et al. 1991
The “[CII] Deficit” Two studies with the ISO LWS found groups of galaxies with
low [CII]/FIR continuum ratios: 30 Normal starforming galaxies (Malhotra et al. 1999)
Galaxies with warmer 60/100 um colors and increasing FIR/Blue ratios – those with higher star formation rates – sometimes had R ~ 2×10-4 – a factor of ten lower than the typical values
Interpreted as higher FUV fields (G0/n)
ULIRG Galaxies (Luhman et al. 1998, 2003) 15 ULIRG galaxies studied and found 80% had [CII] deficits: the
average value was R ~ 6×10-4, or 5 times lower than “starburst” value
Interpreted as most likely due to an additional source of FIR radiation, most likely dust bounded ionization regions – those HII regions with high ionization parameters, U ≡ Q/(4πr2nec) = NHIIαB/c
13
The [CII] and [OI] Line Trace the FUV Radiation Field Strength
~0.1 and 1% of the incident far-UV starlight heats the gas, which cools through far-IR line emission of [CII] and [OI] 63 µm
The efficiency of gas heating is a function of n and G As G rises at constant n, grain charge builds up,
lowering the excess KE of the next photo-electron This is mitigated by raising n, enabling more
recombinations, so that the efficiency ~ G0/n Most of the far-UV comes out as FIR continuum
down-converted by the dust in the PDRs Therefore, the ([CII]+[OI]) to FIR ratio measures the
efficiency, hence G0/n. The combination yields both G and n, since the [CII]/[OI] ratio is density sensitive.
14
The [CII] and [OI] Line Trace the FUV Radiation Field Strength
At a given density, the ratio R ≡ [CII]/FIR uniquely yields G
This single-line utility holds until G/n gets small and column of [CII] determined by ion-eq.
R ∝ 1/G since [CII] line saturates: Above G/n ~ 3×10-3 C+ column
determined by dust extinction ⇒ ~ constant
If n > ncrit weak n dependence If G > 30 then Tgas > 91 K ⇒ weak
G dependence ⇒ Nearly constant I[CII], but FIR
grows with G ⇒ R ∝ 1/G R is smaller for larger G (e.g. Orion
HII region/GMC interface) 15
[CII]/far-IR continuum luminosity ratio vs. density for various G (from Kaufman et al. 2003).
High z [CII] IRAM 30 m telescope used
for first detection at high z J1148+5251 QSO @ z=6.42 Low R (2 × 10-4) ~ local
ULIRGS PDR Model: G ~ 103.8, n =
105 cm-3
Star-formation, 1500 - 3000 per year
Subsequently resolved (PdB): 750 pc radius SFR ~ 1000 M/yr/kpc2
(Walter et al. 2008) 16
Maiolino et al. 2005
Walter et al. 2008
High z [CII]
17
Reported in three other systems from the ground
BRI 1202-0725 QSO @ z = 4.7 (Iono et al 2004) – R ~ 4 × 10-4 high G/n
BRI 0912-0115 QSO @ z = 4.43 (Maiolino et al. 2009) R ~ 1.3 × 10-3 µ ~ 2.5 to 8 ⇒ LFIR ~ 4 × 1012 L “Bright line suggests a different
star formation mechanism at high z compared with local high luminosity galaxies”
BRI 1335-0417 QSO @ z = 4.41 (Wagg et al. 2010) R ~ 5.3 × 10-4
Iono et al. 2006
Maiolino et al. 2009
Wagg et al. 2010
18
The Redshift (z) and Early Universe
Spectrometer: ZEUS
S. Hailey-Dunsheath Cornell PhD 2009
Submm (650 and 850 GHz) grating spectrometer ◊R ≡ λ/Δλ ~ 1200 ◊ BW ~ 20 GHz ◊ Trec(SSB) < 40 K
⇒ Limiting flux (5σ in 4 hours) ~ 0.8 to 1.1 ×10-18 W m-2 (CSO) ⇒ Factor of two better on APEX
Data here from ZEUS – single beam on the sky Upgrade to ZEUS-2 a ◊ 6 color (200, 230, 350, 450, 610, 890 µm
bands); ◊ 40 GHz Bandwidth ◊ 10, 9, & 5 beam system
Design Criteria Choose R ≡ λ⁄Δλ ~ 1000
optimized for detection of extragalactic lines
Near diffraction limit: Maximizes sensitivity
to point sources Minimizes grating size
for a given R Long slit in ZEUS-2
Spatial multiplexing Correlated noise
removal for point sources
Choose to operate in n = 2, 3, 4, 5, 8, 9 orders which covers the 890, 610, 450, 350, 230 and 200 µm windows respectively
ZEUS Windows
2 3 4 5
ZEUS spectral coverage superposed on Mauna Kea windows on an excellent night
500 400 600 700 800 300 Wavelength (µm)
ZEUS Redshift Coverage ZEUS detects [CII] from z ~
1.1 to 2.1 (350 and 450 µm windows) 40% of SMGs
Covers the peak in the star-formation rate per co-
moving volume ZEUS-2 expands [CII]
coverage to z ~ 0.25 to 5: Straddles the peak tracing the
star formation history of the Universe from 11 Gyr ago to the current epoch
Other lines accessible as well:
ZEUS [CII] Windows
Blain et al. 2002, Phys. Rep., 369, 111
[OI] 63 µm: PDRs, n, UV field strength
[OIII] 88 µm: UV field hardness
[NII] 122 & 205 µm: ne tracer, [CII] from HII regions
ZEUS-2 ZEUS-1
First Intermediate z Detection: MIPS J1428 @ z = 1.32 w/ ZEUS/CSO
Moderately lensed (µ→ 10) star forming galaxy Spitzer Bootes field (Borys et al. 2006): LFIR~1.3×1013 L
Detected March 2008 Surprisingly bright: L[CII] ~ 5.4 ×1010 L L[CII] /LFIR ~ 4.2×10-3 Modeled together with CO lines and
FIR: G ~ 500-1000 n ~ 5000-104 cm-3
ISM parameters similar to M82 Extended (kpc-scale) starburst: SFR
~ 2000 M/yr 21
Hailey-Dunsheath, S. 2009 PhD (Cornell) Hailey-Dunsheath et al. ApJ 714, L163 (2010)
([CII]+[OI]) / FIR
[CII]
/ [O
I] Herschel/ PACS Detection of [OI] in
MIPS J1428 Our [CII] detection gives
a good constraint on G0, but...
[CII] and [OI] jointly cool PDRs Sum is much better
estimate on cooling [CII]/[OI] ratio is density
sensitive Constrains G0 and n
much better. Somewhat lower
excitation G0 → 200 n →1000
Sturm et al. 2010
First Herschel [CII] Results: SMM J2135
@ z = 2.3 Highly lensed (µ ~ 32) submm
galaxy Also bright line:
[CII]/FIR ~ 2×10-3 Similar modeling as for MIPS
J1428 with CO lines: G ~ 1000 n ~ 5000
Indicating again, a very extended starburst
Possible detection of [OI] line constraining PDR parameters (Danielson et al. 2010)
23 Ivison et al. A&A Herschel (2010)
A 158 µm [CII] Line Survey of the Galaxies at z ~ 1 to 2: An Indicator
of Star Formation in the Early Universe
G.J. Stacey, S. Hailey Dunsheath, C. Ferkinhoff, T. Nikola, S.C. Parshley, D.J. Benford, J.G. Staguhn,
& N. Fiolet
Stacey et al. ApJ 724, 957
24
ZEUS/CSO z = 1 to 2 [CII] Survey Survey investigates star formation near its peak in the
history of the Universe First survey -- a bit heterogeneous
Attempt made to survey both star formation dominated (SF-D) and AGN dominated (AGN-D) systems
Motivated by detection – at the time of submission, only 4 high z sources reported elsewhere…
LFIR (42.5<λ< 122.5 µm): 4×1012 to 2.5 × 1014 L Report 12 new detections & 1 strong upper limit
Split survey into SF-D, AGN-D and mixed (or poorly characterized) based on the characterization of TIR (3 to 1000 µm) luminosity in the literature– typically dominated by MIR for AGN systems
12 new detections, 1 strong upper limit ◊ 6 SF-D ◊ 5 AGN-D ◊ 3 mixed 25
A Few Optical Images…
Flux
Den
sity
(10-
18 W
/m2 /b
in)
v (km/sec)
Source z LFIR F[CII] (L) (10-18 W-m-2)
RXJ094144 1.819 2.7E13 3.8±0.52
SWIRE J104738+59 1.954 7.5E12 2.8±0.36
J104705+59 1.958 5.7E12 1.7±0.45
SMM J1236 1.222 4.0E12 6.5±0.90
3C 368 1.130 5.1E12 5.1±0.80
MIPS 14282 1.325 1.3E13 19.8±3.0
Star Formation-Dominated
Sample
Flux
Den
sity
(10-
18 W
/m2 /b
in)
v (km/sec)
AGN-Dominated Sample
Source z LFIR F[CII] (L) (10-18 W-m-2)
PKS 0215 1.720 1.1E14 9.4±0.82
3C065 1.176 6.7E12 <0.8
PG1206 1.159 2.6E13 4.2±0.60
PG1241 1.273 5.9E12 15.3±2.2
3C446 1.403 2.5E14 42.8±6.5
Flux
Den
sity
(10-
18 W
/m2 /b
in)
v (km/sec)
Source z LFIR F[CII] (L) (10-18 W-m-2)
SDSS100038 1.720 5.7E12 1.74±0.40
IRAS F10026 1.176 2.0E13 14.4 ±1.1
SMM J22471 1.159 1.0E13 9.3 ±2.1
Mixed or Poorly Characterized Sample
Results: The [CII] to FIR Ratio
30
SB-D:
R = 2.9±0.5 ×10-3
AGN-D:
R = 3.8±0.7×10-4
SB-D to AGN-D ratio is ~ 8:1
Mixed – in between
[CII] Line promises to be an excellent signal for star formation at high z
L[C
II]/L
FIR
LCO/LFIR
G0=102 G0=104
n=106
G0=103
n=105
n=104
n=103 L[CII] / LCO(1-0) = 4100 n=102
Results: [CII], CO and the FIR ⇒ PDR Emission [CII]/CO(1-0)
and FIR ratios similar to those of nearby starburst galaxies
⇒ emission regions in our SB-D sample have similar FUV and densities as nearby starbursters G ~ 400-5000 n ~ 103-104
PDR Modeling
Two sources multiple CO Lines available
PDR parameters well constrained SDSS J100038
G ~ 800 n ~ 4×104 cm
MIPS J1428 G ~ 400 n ~ 8×103 cm-3
32
PDR Modeling Five w/ one CO line available PDR parameters well
constrained SMM J123634
G ~ 500 n ~ 3 ×104 cm
SWIRE J104738 G ~ 400 n ~ 3 ×104 cm-3
SWIRE J104705 G ~ 600 n ~ 6 ×104 cm
IRAS F10026 G ~ 2300 n ~ 1.6 ×103 cm-3
3C 368 G ~ 1000 n < 5 ×104 cm-3
33
G0 from [CII] and FIR
Seven sources have no CO lines available
Can still confidently find Go, since we have learned from above that n ~ 103 -105 cm-3: 3C 065: G < 23,000 PG 1206: G ~10,000 PKS 0215: G ~ 7,000 3C 446: G ~ 5,000 RX J09414: G ~ 3,000 SMM J2247: G ~ 3,000 PG 1241: G ~ 150
34
How Extended are the Starbursts? PDR models constrain G0 and n – if only [CII]/FIR we
have just G0 Since within PDRs, most of the FUV ends up heating
the dust, within PDR models, G0 ~ IFIR
Therefore, a simple ratio IFIR/G0 yields φbeam – which then yields the physical size of the source
Inferred sizes are large – several kpc-scales Galaxies are complex ⇒ plane parallel models are
only a first cut Better to model distributed FUV fields (Wolfire 1990):
G0 ~ λLFIR /D3 λ << D G0 ~ LFIR /D2 λ >> D
λ is the mean free path of a FUV photon D = size of the emitting region 35
Extended Starbursts in the z = 1 to 2 Survey
We use this technique to estimate source sizes based on scaling from M82: Star formation dominated systems:
D ~ 2 kpc for λ << D D ~ 6 kpc for λ >> D
Walter et al. (2009) resolved the [CII] emission from SDSS J1148 +5251 – scaling from this source for high G0 sources (e.g. PG1206) we arrive at much the same answer
For cases where other tracers of star formation are available, our derived source sizes are typically somewhat smaller
Star formation is extended on kpc scales with physical conditions very similar to M82 – with 100 to 1000 times the star formation rate!
36
Star Formation Evolves Our derived physical conditions and source size contrast
markedly with local ULIRGS where: Star formation is relatively confined (< few hundred pc) Star formation has relatively high FUV fields – 10 times larger
than those derived here. Growing evidence for extended starbursts at high z
SMGs radio emission extends over kpc scales (Chapman et al. 2004), with median size ~ 5 kpc (Biggs & Ivison 2008)
CO interferometry of SMGs shows emission over ~ 4 kpc scales (Tacconi et al. 2006, 2008)
CO(3-2) survey of z > 1 sources suggests size scales between 3 and 16 kpc (Iono et al. 2009)
PdBI CO interferometry of MIPS J142824 and SMM 123634: 6.3 × 4.2 & 4.3 kpc scales (Hailey-Dunsheath et al., Engle et al. in prep.)
Likely the effect of much more massive molecular disks in the early Universe.
37
A Curious Situation
R is significantly smaller for AGN-D systems ⇒ FUV fields significantly larger For the same source luminosity, one would therefore
derive a smaller beam filling factor, hence smaller size But, the AGNs are significantly more luminous ⇒
derive similar source size: D ~ 1-3 kpc for λ << D D ~ 3-12 kpc for λ >> D Exception is 3C065 with D < 0.6-0.9 kpc
The AGN-D sources have much more intense, but similar sized starbursts as the SB-D sample.
38
What Causes this Dichotomy? 1. What if the FIR in AGN comes from another source? PAH and [NeII] line studies suggest most of the FIR from
both local AGN, and z ~ 2 AGN has its origins in star formation (Schweitzer et al. 2006, Shi et al. 2007, Lutz et al. 2008)
Relationship between the 2-10 KeV X-ray and IR luminosity from AGN: pure systems, LX-ray/LFIR~0.45 (Ruiz et al. 2007) Using this scaling, for all but one source (PKS 0215) we
find < 5% of the FIR is associated with the AGN. For PKS 0215 we also show the [CII] emission might
arise from an XDR (torus) associated with the engine For other sources, we expect little [CII] from the BLR,
NLR or XDR Conceivable that the FIR from our two blazars (PKS 0215
and 3C446) is relativistically boosted synchrotron radiation
What Causes this Dichotomy? 2. It could simply be that the z = 1 to 2 SB-D and AGN-D
systems are distinct populations tracing different evolutionary paths
40
What Causes this Dichotomy? 3. It might be there is a temporal link between the SB-D and
AGN-D sources: Onset of starburst and AGN activity could be coeval, or Onset of AGN activity stimulates a kpc-scale starburst The starburst ages as AGN activity shuts down
Young, intense starburst associated with AGN-D system evolves into less intense, but still extended SF-D systms Consistent with deep surveys that appear to show the peak of
AGN activity slightly before the peak of star formation activity Observational support: [OIII] emission traces O stars. With
ZEUS/CSO we detected [OIII] 88 um from two high z (2.8 & 3.9) composites (Ferkinhoff et al. 2010), and PACS/Herschel [OIII] 52 um from MIPS 1428 and the composite FSC 10214 (Sturm et al. 2010) Ranked in order of high to low [OIII]/FIR ratio, the AGN-D
systems tend to have strong lines ⇒ with younger starburst 41
Preferred, and testable solution: [OIII] ratio is density sensitive – how extended is [OIII] region?
If AGN generated [OIII], can test with [OIV] 24 um line.
ZEUS/CSO [OIII] at High z
O++ takes 35 eV to form, so that [OIII] traces early type stars
Transmitted through telluric windows at epochs of interests: 88 µm line at z ~ 3 and 4 (6) for ZEUS (ZEUS-2) 52 µm line at z ~5.7 and 7.7! --- much more challenging
Detectable in reasonable times for bright sources
42
ZEUS/CSO Detections
Detected in in 1.3 hours of integration time on CSO – differences in sensitivity reflect telluric transmission
Two composite systems APM 08279 extremely lensed (µ → 4 to 90) SMM J02399 moderately lensed (µ ~ 2.38)
43
Ferkinhoff et al. 2010 ApJ 714, L147
Characterizing the Starbust/AGN [OIII]/FIR
APM 08279 ~ 5.3 × 10-4; SMM J02399 ~ 3.6 × 10-3 Straddles the range (2×10-3 ) found in local galaxies
(Malhotra et al. 2001, Negishi et al. 2001, Brauher et al. 2008)
Origins of [OIII]: APM 08279 Very few tracers of star formation available: e.g. Hα,
Paα, Paβ lines are broad and variable with luminosities 100 times larger relative to [OIII] 88 µm than for M82
Spitzer PAH upper limit 10 × F[OIII], and expect ~ unity
Build both starburst and AGN model
AGN Origin for APM 08279? AGN: NRL ne ~ 100 – 104 cm-3 <ne> ~ 2000 cm-3
(Peterson 1997) For this ne range, [OIII] 5007 Å/ [OIII] 88µm ~ 1 to
100 Using this relationship and the fact that: LO3, 5007 ~
Lbol/3500 (Kaffmann & Heckman 2005) ⇒ expect L[OIII] 88 µm ~ 1 to 100 × 1010 /µ L (fcn ne) ⇒ all 1011 /µ L [OIII] may arise from NLR if ne > 2000
cm-3
Starburst Origin for APM 08279 [OIII]/[NII] line ratios
insensitive to ne, but very sensitive to Teff [OIII]/[NII] 122 especially
so… Ratio in APM 08279 > 17
based on non-detection of 205 µm (Krips et al. 2007) ⇒ Teff> 36,000 K ⇔ O9
stars If starburst headed by
O7.5, then 35% of FIR from starburst: SFR ~ 12,000/µ M/year 46
From Rubin, R. 1985
Starburst Origin for SMM J02399
Ivison et al. 2010 argue for starburst origin of FIR 6.2 µm PAH flux ~ [OIII] 88 µm line flux as for
starbursters Using scaling laws and the observed Lα, [OIII] 5007
Å and 88 µm fluxes we estimate: [OIII]/Hα (sensitive to Teff) and [OIII] 5007 Å/ [OIII]88 µm (sensitive to ne and Te) Yields: Teff ~ 40,000 K (O7.5) an ne ~ 300 cm-3
SMM J02399 fit by a starburst headed by O7.5 stars, forming stars at a rate ~ 5000/µ per year.
47
PACS [OIII] 51.8 µm Detections
PACS/Hershel detections of [OIII] 51.8 µm line from two sources
PACS takes advantage of happy coincidence: 25.9 x 2 = 51.8
[OIV] 25.9 µm (2nd order), [OIII] 51.8 µm (1st order)
Line ratio very sensitive tracer of AGN
48 Sturm et al. 2010
To form O++ takes 35.1 eV; to form O+++ takes 54 eV Strong [OIV] requires an AGN on galactic scales – the
[OIII] 88 / [OIV] 26 ratio is as good as NeII/NeV 49
[OIV] 26 µm: AGN AGN
Starbursts
PACS/ZEUS Synergy
Bright fine-structure lines of roughly equal luminosity for most galaxies
ZEUS has roughly same sensitivity (W/m2) at 350 µm as PACS does from 100 to 200 µm
Therefore, ZEUS can detect [CII] line in z = 1 to 2 interval as PACS detects the [OI] (63 µm), and [OIII] (52 and 88 µm) lines in the same redshift range.
Even get the [OIV] 25.9 um AGN tracer (same L as [OIII]!) for free.
Powerful diagnostics of stellar types and the presence of AGN
50
51
ZEUS [CII] Work in Perspective Observations of [CII] at z ~ 1
to 2 characterize star formation in galaxies at the historic peak of star formation in the Universe
ZEUS on the CSO provides a unique opportunity to explore this epoch through the [CII] line
Approximately 40% of the submm galaxy population has redshifts such that the [CII] line falls in the 350 (z ~ 1) or 450 (z~2) µm windows
ZEUS [CII] Windows
Blain et al. 2002, Phys. Rep., 369, 111
With ZEUS-2 on CSO and APEX we can extend these studies from z ~ 4 to 0.25 -- tracing the history of star formation from its peak 11 Gyr ago to the present epoch
ZEUS-2 ZEUS-1
The Near Future: ZEUS-2 Upgrading to (3) NIST 2-d
TES bolometer arrays Backshort tuned 5 lines in 4 bands
simultaneously 215 µm (1.5 THz) 350 µm (850 GHz) 450 µm (650 GHz) 625 µm (475 GHz)
Imaging capability (9-10 beams)
Simultaneous detection of [CII] and [NII] in z ~ 1-2 range
First light in January 2011 on CSO with 400 um array only
APEX later in 2011
spectral
CO(7-6)
[CI] 370 µm 13CO(6-5) µm
[CI] 609 µm
[NII] 205 µm
9 × 40 400 µm array
10 × 24 215 µm array
5 × 12 625 µm array
spatial
Imaging Capabilities
M51 - CO(1-0): BIMA Song (Helfer et al. 2003)
Astrophysics [CI] line ratio: Strong
constraints on T 13CO(6-5) line: Strong
constraints on CO opacity [NII] line: Cooling of
ionized gas, and fraction of [CII] from ionized media
Mapping Advantages Spatial registration
“perfect” Corrections for telluric
transmission coupled Expected SNR for the five
lines comparable
12CO(7-6) 13CO(6-5)
[CI] 3P2 - 3P1
[NII] 3P1 - 3P0
[CI] 3P1 - 3P0
The Near Future: ZEUS-2
54
FS Lines and ALMA When complete, the ALMA array will be ~ 20 to 30
times more sensitive than ZEUS on APEX
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ZEUS-2 Line Sensitivities on APEX
4E11
4E10
4E9
8E8
Band 10
4E12
4E11
4E10
8E9
Conclusions [CII] line emission at high z
Reveals star forming galaxies High star formation rates with local starburst-like
physical conditions ⇒ Extended starbursts Extended starbursts in AGN
[CII] from XDR? [OIII] emission at high z
Traces current day stellar mass function Also can traces physical conditions of NLR – may
have detected it from APM 08279 Future with ALMA exciting – resolve sources that are
10’s of times fainter 56
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