[OIII]/[CII]比とALMA Cy2の初期結果
井上昭雄（大阪産業大学）

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2014/12/02-03

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[CII]158 deficit in high-z galaxies?

SDF-LBG@z=6.315(3-sigma u.l.)<tentative>
Ota et al. 2014

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[CII]158 deficit in high-z galaxies?
• Low [CII]– Truncated PDR (matter-bounded, high-ionization)– Low C abundance→ Check other PDR lines, HII region lines, andCIII/CIV lines

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[OIII]88/[CII]158 diagnostics• [OIII]88 traces HII gas• [CII]158 traces HI gas• Matter-bounded or photon-bounded?

Tielens & Hollenbach 2005
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Cloudy HII/PDR calculationc.f. Abel et al. 2005, Nagao et al. 2011/2012• Plain-parallel• Constant pressure• Orion chemical abundance (He & N modified)• Orion grains and PAH• B=10microG• Turbulent pressure = magnetic pressure– v_tur = 3.3 km/s (B/10uG)(n/1e5 cm-3)^-1/2• CMB @ z=7• Haardt & Madau (2005) background @ z=7• Cosmic ray background at MW ISM
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Cloudy HII/PDR calculation• Stellar spectra taken from SB99
– Padova track, Salpeter IMF 1—100 Msun, 10Myr?
– Z=0.0004, 0.004, 0.008, 0.02
• Ionization parameter: U= ion photon flux/c/n_H– logU=-3.0, -2.0, -1.0

• Hydrogen density (at the top of slab)– logn_H=2.0, 3.0, 4.0

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Vacuum space

HIIHI

H2
Cosmicrayheating isimportant“Emergent”
line ratios

Dust effects:(1) Heating/cooling sources.
- Photoelectric heating is the main heat source in HI phase.
(2) Lyman continuum absorption.
(3) Non-ionizing continuum absorption.
- Photon shielding for H2 formation.
- How much energy is absorbed by dust?  L_IR
(4) Line photon absorption, especially Ly-alpha.

Radiation
Density jump determined by pressure
equilibrium  B, turbulent pressures
Or constant density assumption
Plain-Parallel geometry
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Ionization structure

HII

HI

H2CII
CIII
OII
OIII

CO

HII

CIVHI

CIII

CII

COCI

OI

COCI
OI

COOIII
OIV

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2014/12/02-03

H2OII
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[OIII]88 & [CII]158 lines

De Looze+14 (z>0.5)

De Looze+14 (all)Scales may be wrong!

Scales may be wrong!

Red: logU=-3.0, Green: logU=-2.0, Blue: logU=-1.0
Dotted: logn=2.0, Solid: logn=3.0, Dashed: logn=4.0

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De Looze+14 (z>0.5)

De Looze+14 (all)2014/12/02-03

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Nearby galaxies’ [OIII]/[CII]

Nearby galaxies[OIII]/[CII]~0.1—10
Low-Z galaxies[OIII]/[CII]=1—10

Madden et al. (2012)

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[OIII]88 & [CII]158 lines•Z=0.02 fully PDR (logNH>23.5 or Av>10) can explain nearby galaxies’s ratio.
– NOTE: CMB and UVB at z=7••

Lower-Z galaxies may have higher U.
High-z galaxies tend to have higher U (and lower-Z), suggesting higher [OIII]/[CII].
Red: Z=0.02, Blue: Z=0.0004

logU=-1.0

Low-Z
logU=-3.0

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Summary• Very high-z (z>6) galaxies are faint in [CII].
• To understand the [CII] deficit, a series of PDR
calculations are performed (or performing).
– A lot of parameters…
– Need comparisons with observations• [OIII]/[CII] ratios of nearby galaxies can be reproduced
by fully PDR models.
• [OIII] observations of high-z [CII] deficit galaxies arerequired.
• For Cy3, galaxies detected in CIII]1909 are quiteinteresting.
– Stark et al. 2014

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2014/12/02-03

12おまけ：HII REGION LINES AMONGDIFFERENT POPULATION SYNTHESIS
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Absolute QHI?
• Stellar rotation and massive star binaryenhance QHI by a factor of 2.
0.3 dex

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2014/12/02-03

14QHI/QHeI: Spectral shape of LyC 1• Small difference among population synthesis
models  Emission line ratios are robust?

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QHI/QHeII: Spectral shape of LyC 2• Large difference between new and previous
models  Large difference in HeII lines?

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HeII 1640/Hb ratio• Yes, large difference appears.

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What nebular parameters?
• Z dependent logU?

Model: MAPPINGSIII
logU=-2.3

logU=-2.9
logU=-3.2

Nagao+06
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What nebular parameters?
• Z dependent logU?
-1.0
-1.5
-2.0
-2.5

Densitydependence

logU=-3.0

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Z dependent logU?

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Z dependent logU?

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Summary for HII region lines• Absolute QHIs are a problem.

– Rotation and massive binary boost QHI by a factor of 2.

• Difference in LyC spectral shape among
population synthesis models is relatively small,but be careful about highly excitation lines, e.g.
HeII
• A fiducial nebular parameter set can be useful forusers.
– Metallicity dependent U (ionization parameter)?

• Different Z-U relations obtained from different line ratios– A constant density, logn=2, seems OK?
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