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Unveiling the nature of z≈6 galaxies through [CII] emission studies
Molecules and dust as fuel to star forma=on 21st – 24th June 2016
Simona Gallerani
in collabora=on with:
Livia Vallini, Andrea Ferrara, Andrea PalloMni, Roberto Maiolino, Chiara Feruglio, Dominik Riechers, Bin Yue
Unveiling the nature of z≈6 galaxies through [CII] emission studies
Molecules and dust as fuel to star forma=on 21st – 24th June 2016
Simona Gallerani
in collabora=on with:
Livia Vallini, Andrea Ferrara, Andrea Pallo2ni, Roberto Maiolino, Chiara Feruglio, Dominik Riechers, Bin Yue
Searching for galaxies in the epoch of reioniza=on
zrec≈ 1100
Keck telescope (e.g.)
trec≈ 400,000 yr
zreio≈ 6-‐7 treio≈ 1 Gyr
t
z
Dropout tecnique: Lyman Break Galaxies
Narrow band technique: Lyman Alpha Emi`ers
Searching for galaxies in the epoch of reioniza=on
zrec≈ 1100
Keck telescope (e.g.)
trec≈ 400,000 yr
zreio≈ 6-‐7 treio≈ 1 Gyr
t
z
Dropout technique: Lyman Break Galaxies
Narrow band technique: Lyman Alpha Emi`ers
INTRINSIC DIFFICULTIES
Uncertain=es on the galaxy redshibs (Δz/z≈10%) Contamina=on from foreground red galaxies
and Galac=c cool stars
Ionized bubbles allow Lyα photons to escape. The neutral hydrogen frac=on increases at redshibs
approaching the EOR. The HII region sizes decrease.
HII
Is the [CII] emission line a valid alterna:ve?
HII
HII
local dwarfs by (De Looze et al. 2014)
[CII] emission observa=ons in the local Universe
Ø Major coolant of the ISM in star forming galaxies
Ø The strongest emission line in most galaxies (L[CII] ~ 0.1-‐1% LFIR)
At z > 4 is redshibed into the mm à detectable with ALMA
[CII] emission observa=ons in 5 < z < 7 galaxies
NO DETECTIONS
Contours levels in steps of 1σ (0.08 m
Jy beam-‐1)
Ouchi et al. (2013)
0.8’’ x 0.6’’
tON = 3.2 h
[CII] in 6.5 < z < 7 LAEs (CARMA+PdBI)
Gonxalez et al. (2014)
[CII] in Himiko at z = 6.6 (ALMA)
[CII] emission observa=ons in 5 < z < 7 galaxies
DETECTIONS
Capak et al. (2015)
[CII] in Himiko at z = 6.6 (ALMA)
[CII] in 6 < z < 7 (ALMA)
Maiolino et al. (2015) Willo` et al. (2015)
What can we learn from high-‐z [CII] observa=ons on z ≈ 6 galaxy proper=es?
DETECTIONS
Capak et al. (2015)
[CII] in Himiko at z = 6.6 (ALMA)
[CII] in 6 < z < 7 (ALMA)
Maiolino et al. (2015) Willo` et al. (2015)
NO DETECTIONS
Contours levels in steps of 1σ (0.08 m
Jy beam-‐1)
Ouchi et al. (2013)
0.8’’ x 0.6’’
tON = 3.2 h
[CII] in 6.5 < z < 7 LAEs (CARMA+PdBI)
Gonxalez et al. (2014)
[CII] in Himiko at z = 6.6 (ALMA)
cold neutral medium (CNM) warm neutral medium (WNM) molecular clouds (MCs)
The mul=-‐phase structure of the interstellar medium
H2 I
pressure equilibrium CNM ßà WNM
see also talk by Mark Wolfire
Simula=ons of [CII] emission in a z ≈ 6 galaxy
Zoomed hydro RT simula=on with a subgrid model
for the WNM/CNM (Wolfire et al. 2003)
and molecular clouds (Padoan & Nordlund 2011)
(Baek et al. 2013)
5 kpc 5 kpc
5 kpc 5 kpc �2.8
�2.4
�2.0
�1.6
�1.2
�0.8
�0.4
0.0
log(
Z/Z �
)
Lbox = 10 h-‐1 Mpc Mres = 7 x 105 M¤ Mhalo = 1011 M¤
Vallini et al. (2013) Vallini et al. (2015)
UCL PDR
�1.0 �0.5 0.0 0.5 1.0 1.5 2.0Log (SFR/M� yr�1)
�1.2
�1.0
�0.8
�0.6
�0.4
�0.2
0.0
Log
(Z/Z�)
5.000
6.000
7.000
8.000
9.000
Him
ikoIOK-1
HCM6A
A17031
z8GN
DSD
FJ3058
5
6
7
8
9
Log
(LC
II/L�)
log(LCII) = 7.0 + 1.2 × log(SFR) + 0.021 × log(Z) + 0.012 x log(SFR)log(Z) − 0.74 × log2(Z)
Yue et al. (2015)
Simula=ons of [CII] emission in a z ≈ 6 galaxy
5 kpc 5 kpc
5 kpc 5 kpc �2.8
�2.4
�2.0
�1.6
�1.2
�0.8
�0.4
0.0
log(
Z/Z �
)
(Bell et al. 2005, 2007; Bayet et al. 2009)
Simula=ons of [CII] emission in a z ≈ 6 galaxy
No detec:on of [CII] emission in z≈6 galaxies can be explained with low gas metallicity values (Z < 0.2 Zsun)
or by nega:ve stellar feedback disrup:ng MC.
[CII] emission arises predominantly from PDRs
(Fdiff/Ftot <40%)
0.00
0.02
0.04
0.06
0.08
Flux
(mJy
)
CNM
PDRs
SFR=1.0 M� yr�1
-100 0 100 200 300velocity (km/s)
0.00
0.25
0.50
0.75
Flux
(mJy
)
SFR=10.0 M� yr�1
Vallini et al. (2015)
Vallini et al. (2015)
Simula=ons of [CII] emission in a z ≈ 6 galaxy
No detec:on of [CII] emission in z≈6 galaxies can be explained with low gas metallicity values (Z < 0.2 Zsun)
or by nega:ve stellar feedback disrup:ng MC.
Deficit of CII at the loca=on of the UV emission
The CII is detected in the displaced clump
Maiolino et al. (2015)
Capak et al. (2015)
Simula=ng cosmic metal enrichment by the first galaxies
PalloMni et al. (2014)
AMR code (RAMSES) 10 Mpc h-‐1
Mdm≈ 5 x 105 Msun Δx ≈ (20-‐1) kpc h-‐1
1.54 1.20 0.96 0.78 0.65 0.56 0.48 0.42t [Gyr]
�4.5
�4.0
�3.5
�3.0
�2.5
�2.0
�1.5
�1.0
log[SFR/(M�yr�1Mpc�3)]
4 5 6 7 8 9 10 11z
Total
Pop III
Bouwens et al. 2012
Zheng et al. 2012
�22 �20 �18 �16 �14 �12MUV
�6
�5
�4
�3
�2
�1
log(�
UV/m
ag/M
pc3)
Luminosity functionat z = 6
simulated
observed
Schechter fit
The UV luminosity func=on of z ≈ 6 galaxies
Good greement between simula=ons and UV LF observa=ons (Bouwens et al. 2015)
PalloMni et al. (2015)
�22 �20 �18 �16 �14 �12MUV
�6
�5
�4
�3
�2
�1
log(�
UV/m
ag/M
pc3)
Luminosity functionat z = 6
simulated
observed
Schechter fit
[CII] emission in z ≈ 6 galaxies
PalloMni et al. (2015)
�1.0 �0.5 0.0 0.5 1.0 1.5 2.0Log (SFR/M� yr�1)
�1.2
�1.0
�0.8
�0.6
�0.4
�0.2
0.0
Log
(Z/Z�)
5.000
6.000
7.000
8.000
9.000
Him
ikoIOK-1
HCM6A
A17031
z8GN
DSD
FJ3058
5
6
7
8
9
Log
(LC
II/L�)
Vallini et al. (2013/2015)
Good greement between simula=ons and UV LF observa=ons (Bouwens et al. 2015)
�22 �20 �18 �16 �14 �12MUV
�6
�5
�4
�3
�2
�1
log(�
UV/m
ag/M
pc3)
Luminosity functionat z = 6
simulated
observed
Schechter fit
0 100 200 300 400 500
0
100
200
300
400
500
5 arcsec
beam
X-18.8
X-18.8
X-17.6
X-17.6
X-16.5
X-16.5
X-16.3
X-15.4
X-15.0
X-13.0
X-13.6
X-14.0
galaxy emission
�100
�10�1
�10�2
+10�2
+10�1
+100
�I/µJy/beam
PalloMni et al. (2015)
[CII] emission in z ≈ 6 galaxies
Good greement between simula=ons and UV LF observa=ons (Bouwens et al. 2015)
�22 �20 �18 �16 �14 �12MUV
�6
�4
�2
0
2
4
6
log(Fpeak/µ
Jy)
[CII] flux - MUV relation
simulated (z = 6)
extrapolated (z = 6)
Maiolino et al. 2015 (z ' 7)
Capak et al. 2015 (z ' 5.5)
Willott et al. 2015 (z ' 6)
Good greement between simula=ons and [CII] observa=ons
�22 �20 �18 �16 �14 �12MUV
�6
�5
�4
�3
�2
�1
log(�
UV/m
ag/M
pc3)
Luminosity functionat z = 6
simulated
observed
Schechter fit
Good greement between simula=ons and UV LF observa=ons (Bouwens et al. 2015)
PalloMni et al. (2015)
[CII] emission in z ≈ 6 galaxies
�22 �20 �18 �16 �14 �12MUV
�6
�4
�2
0
2
4
6
log(Fpeak/µ
Jy)
[CII] flux - MUV relation
simulated (z = 6)
extrapolated (z = 6)
Maiolino et al. 2015 (z ' 7)
Capak et al. 2015 (z ' 5.5)
Willott et al. 2015 (z ' 6)
Good greement between simula=ons and [CII] observa=ons
�22 �20 �18 �16 �14 �12MUV
�6
�5
�4
�3
�2
�1
log(�
UV/m
ag/M
pc3)
Luminosity functionat z = 6
simulated
observed
Schechter fit
Good greement between simula=ons and UV LF observa=ons (Bouwens et al. 2015)
PalloMni et al. (2015)
MUV = -‐19 à 40 hr ALMA MUV = -‐18 à 2000 hr ALMA
at 4σ
Challenging to detect reioniza=on sources even with ALMA … unless lensed galaxies
[CII] emission in z ≈ 6 galaxies
The importance of ou~lows in z ≈ 6 galaxies
Ou~lows shape the galaxy star forma=on histories and can produce cavi=es in their interstellar medium that may allow ionizing photons to escape
Invoked by theore=cal model to explain the discrepancy in the low-‐mass tail of the stellar mass func=on with the dark ma`er halo mass func=on
Quasar absorp=on studies show that the inter-‐galac=c medium is enriched with metals up to z ≥ 6
D’Odorico et al. (2013)
Detec=on of broad wings in the [CII] line of a z=6.4 quasar
Maiolino et al. (2012)
Beam: 2” Beam: 1”
Cicone et al. (2015)
Signatures of ou~lowing gas in z ≈ 6 quasars
see also talk by Alberto Bola`o
Signatures of ou~lowing gas in z ≈ 6 quasars
Are broad wings also present in [CII] lines of z≈6 galaxies?
Maiolino et al. (2012)
Beam: 2” Beam: 1”
Cicone et al. (2015)
No evidence in single sources Stacking of 9 galaxy spectra
Stacking the residuals of Capak et al (2015) galaxy spectra
We tenta+vely detect ( at ≈ 3σ) a flux excess in the stacked signal that strongly deviates from a standard normal distribu:on
Is this the signature of ou~lowing gas we were looking for?
Stacking the residuals of Capak et al (2015) galaxy spectra
0.00
0.02
0.04
0.06
0.08
Flux
(mJy
)
CNM
PDRs
SFR=1.0 M� yr�1
-100 0 100 200 300velocity (km/s)
0.00
0.25
0.50
0.75
Flux
(mJy
)
SFR=10.0 M� yr�1
Vallini et al. (2015)
Galaxy emission line profiles
Maiolino et al. (2012)
Deblok et al. (2016)
Double Gaussian profile
Double horn profile
Gaussian profile +
satellites
Evidence for ou~lows in z ≈ 6 galaxies with ALMA
The double Gaussian is the favored profile for the observed [CII] emission lines
χ 2obs =12.6
ndof =17
P(χ 2 > χ 2obs ) = 0.8
χ 2obs =16.5
ndof =16
P(χ 2 > χ 2obs ) = 0.4
χ 2obs = 69
ndof =18
P(χ 2 > χ 2obs )<10
−4
Evidence for ou~lows in z ≈ 6 galaxies with ALMA
The flux excess we detect is consistent with a loading factor ≈ 0.4
loading factor =M
SFR
Comparison with z<0.2 starburst galaxies:
Heckman et al. (2015)
loading factor =M
SFR
5≤ SFR[ M yr−1]
≤ 70
−1.3≤ log10M
SFR≤ 0.6
100 ≤voutflow[km s−1]
≤ 500
Proper=es of the Capak et al. (2015)
sample
Dahlia (PalloMni et al. 2016) Density
Temperature
Pressure
Metallicity
16 kpc 4 kpc 1 kpc
-‐4 log n [cm-‐3] 2.4 -‐4 log n [cm-‐3] 3.0 -‐3 log n [cm-‐3] 1.8
3.3 log T [K] 5.7 3.2 log T [K] 6.0 3.9 log T [K] 6.3
-‐2.8 log Z [Zsun] 0.4
0 log P [K cm-‐3] 8.0 3.0 log P [K cm-‐3] 7.8 0.8 log P [K cm-‐3] 7.2
-‐2.8 log Z [Zsun] 0.4 -‐2.8 log Z [Zsun] 0.4
Lbox [Mpc h-‐1]
MDM [Msun h-‐1]
Δxmax [kpc h-‐1]
Δxmin [pc]
cosmo 20 3 x 107 78 -‐
zoom 2.1 7 x 104 10 32
STAR FORMATION H2 dependent SK rela=on (Krumholz et al. 2009) STELLAR FEEDBACK • SN explosion: thermal and kine=c (blast-‐wave model by Ostriker & McKee) • stellar wind • radia=on pressure
AMR code (RAMSES) MDM = 1.8 x 1011 Msun Mstar = 1.6 x 1010 Msun MH2 = 3.6 x 108 Msun SFR = 100 Msun yr-‐1
Molecular hydrogen
5.2 log ΣH2 [Msun kpc-‐2] 8.4
3 kpc
Numerical simula=ons of a z ≈ 6 galaxy
Gallerani et al. (2016)
PalloMni et al. (2016)
SUMMARY
The [CII] emission line is a promising tool for characterizing the ISM of high-‐z galaxies
Vallini et al. (2013-‐2015)
No detec:on for Z < 0.2 Zsun galaxies
SUMMARY
The [CII] emission line is a promising tool for characterizing the ISM of high-‐z galaxies
�22 �20 �18 �16 �14 �12MUV
�6
�4
�2
0
2
4
6
log(Fpeak/µ
Jy)
[CII] flux - MUV relation
simulated (z = 6)
extrapolated (z = 6)
Maiolino et al. 2015 (z ' 7)
Capak et al. 2015 (z ' 5.5)
Willott et al. 2015 (z ' 6)
Detec=ons of the [CII] line emi`ed by the sources of cosmic reioniza=on are challenging even for ALMA (unless lensed)
Vallini et al. (2013-‐2015) PalloMni et a
l. (2014-‐2015)
No detec:on for Z < 0.2 Zsun galaxies
MUV = -‐19 à 40 hr ALMA MUV = -‐18 à 2000 hr ALMA
SUMMARY
The [CII] emission line is a promising tool for characterizing the ISM of high-‐z galaxies
�22 �20 �18 �16 �14 �12MUV
�6
�4
�2
0
2
4
6
log(Fpeak/µ
Jy)
[CII] flux - MUV relation
simulated (z = 6)
extrapolated (z = 6)
Maiolino et al. 2015 (z ' 7)
Capak et al. 2015 (z ' 5.5)
Willott et al. 2015 (z ' 6)
Tenta+ve detec=on of ou~lowing gas from the [CII] emission line profile
in a sample of z ≈ 6 galaxies
Vallini et al. (2013-‐2015) Gallerani et al. (2016) PalloM
ni et al. ()2016 PalloMni et a
l. (2014-‐2015)
No detec:on for Z < 0.2 Zsun or MC photoevapora:on
Detec=ons of the [CII] line emi`ed by the sources of cosmic reioniza=on are challenging even for ALMA (unless lensed) MUV = -‐19 à 40 hr ALMA MUV = -‐18 à 2000 hr ALMA
100 <voublow < 500 [km/s]
Comparison with z<0.2 starburst galaxies:
Heckman et al. (2015)
loading factor =M
SFR
Newman, Genzel et al. 2012
MC photo evapora=on effects on the [CII] emission
ICM$
clump$(ncl,$rcl,$Nc)$
$FUV$photons$
(Habing$+$ionizing)$
G0$
FIR$line$emission$$from$clumps$
MGMC=9�104$M!$
FIR$line$emission$$from$ICM$
stellar$metallicity$
(Z*)$gas$
$metallicity$(Z)$
starburst$
Vallini et al. (2016), submi`ed to M
NRAS
Deficit of CII at the loca=on of the UV emission
The CII is detected in the displaced clump
The inclusion of MC photo evapora:on strongly reduces [CII] emission possibly explaining no detec:ons in some of the targeted z≈6 galaxies
Galaxy emission line profiles