第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow and outflow rate of star-forming
galaxies at z~1.4
Kiyoto Yabe (Kavli IPMU)

Based on Yabe et al 2015, ApJ, 798, 45
Collaborators: Kouji Ohta (Kyoto Univ.), Masayuki Akiyama(Tohoku Univ.), Naoyuki Tamura (Kavli IPMU), Fumihide
Iwamuro (Kyoto Univ.), Gavin Dalton, Andrew Bunker(Oxford Univ.), Akifumi Seko (Kyoto Univ.), FMOS GTO team
& FastSound team

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Scientific Background:• Star-formation history traced by gas phase metallicity✓ Metallicity as a tracer of the past star-formation activity✓ Correlation between stellar mass and metallicity (mass-metallicity

relation; MZR)
✓ MZR evolves with redshift (higher metallicity with increasing redshift)✓ MZR at z>1 still remains unclear due to limited sample size
• Metallicity is affected by gas inflow (dilution effect) and outflow (expel ofenriched gas)
Tremonti+2004

The Astrophysical Journal Letters, 771:L19 (6pp), 2013 July 10

Zahid etZahid+13, ApJ, 771, L19
z~1.4
z~0.1

metallicity

metallicity

z~0.3

stellar mass

z~0.8
z~2.3

stellar mass

Figure 1. MZ relation at five epochs ranging to z ∼ 2.3. The curves are fits to the data defined by Equation (4). The solid curves indicate metallicities determi
using the KK04 strong-line method and the dashed curves indicate metallicities converted using the formulae of Kewley & Ellison (2008). Data presented in this fig
can be obtained from H.J.Z. upon request.

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Importance of Inflow and Outflow:• Various observational evidences of gas outflows in high-z galaxies
hysical Journal, 752:111 (19pp), 2012 June 20• Strong and ubiquitous outflows at high redshift
OUTFLOWS FROM DEEP2 STAR-FORMING GALAXIESNewman et al.

203

wind velocity is higher in galaxies withlarger stellar mass and high SFR?

flow absorption component 1 − Aflow compared for galaxies in (upper panel) the three subsamples of stellar mass; (lower panel) the three
V . Velocity is referred to Mg ii 2795.5 Å. A 5 pixel boxcar smooth has been applied. In each panel, the red, green, and blue lines are for highWeineret al.
ApJ,
187
Newmanetandal.for
2012,
ApJ, 752, 111
The verticallines at −400
km 2009,
s−1 to −650
kmFigures−1692,
show2.
thelocation of line
V10% ,profiles
where theandoutflow
The high-mass
Emission
bestcrosses
fit to10%Hαabsorption.
and [N ii]λ6584
featuressix regions of ZC406690: clump A, c
−1−1
w greater outflow absorption at -800 km s < V < −400 km s than the lower-mass or SFR samples.

marksscaled such that the distance between the tails is 260 km s21. The circle
20u230u,
so the streams
cover
a totalangular area of ,0.4 rad2, namejectedmajor
axis,
makingitpossible
to
test
these
Ha/[N
II]; figs. S1 and S2).
第2回 銀河進化研究会@名古屋大学
entropy, log K 5 log(T/r2/3), in unitsof the The per
the halo virial radius,
Rv. The2015/06/03-05
cent ofthe sphere.
When viewed
givenhigh-resolution
direction, thecolu
predictions.
associatedstar-forming
galaxyAnalysisfromof aa deep
VLT/
5
20
22
K is above
10 cm
for 25%of Spectrothe areavirial quantities, highlights (in red) the high-entropy medium fillingwith
theredshift
halo z =density
cold gas2.3285 isoflocatedjustbelow
26 kpc10 UVES
(Ultraviolet
and Visual
Echellethe dampedthe
Lymanseen thegraph)
spectrumof thethe backgroundHE w
lowvirialabsorberradius.(DLA)
Althoughpicturesshow
inner disk,quasar
the diskout to the virial shock outside Rv. It exhibits (in blue) three radial,fromtowardthequasarHE
2243–60(14).
The
galaxy2243–60
(fig.
S5)
(17)
shows
that
the
gas
meentropy streams that penetrate the inner disk, seen edge-on. The radial flux
not resolved, so associated phenomena such as shocks, star formatio
was detected in our z ≈ 2 SINFONI (15) survey, tallicity can give us insights into the physical_ 5 r2rvr, in solar masses per year per square radian,where
per solid angle is m
feedback are treated in an approximate way only (see density maps
Importanceof
cold
accretion
of
gas
in
the
galaxyevolution
calledthe
SINFONI
Mg II Programfor Line nature of the gas. In particular, the total H I colthanr is the gas density and vr the radial velocity. It demonstrates that more
additional
cases
in Supplementary
Figs /cm
3–5).
–2 Kvir, virial entropy.
Emitters(SIMPLE)(16). Recent
adaptive
optics umn is log(N) ≈ 20.6 (i.e., almost entirelyH
90% of the observational
inflow is channelled throughthe streams (blue),at a ratethatSomeevidenceof gasinflowat highredshift?
(AO)–assisted
SINFONIobservations(17) of neutral) and, from the undepleted low-ionization

Importance of Inflow and Outflow:••
this z = 2.3285 star-forming galaxy (Fig. 1A), ion Zn , the gas metallicity ([Zn/H] = –0.72 T
thedirectdetectionofpristinegas
still(VLT)
difficult...is much lower than that of the galaxy
obtained atinflow
the Very Largeis
Telescopewith 0.05)• But,
ð (17)
uniformly in r, using the fact that the velocity along the streams
is arc sec) resolution (table S1), allow ([O/H]~1 kpc (0.25= –0.35 T 0.1 dex). This comparison disII?

roughly constant (Supplementary Information, sections 5 and 6).
This is convolved with the halo mass function23, n(Mv), to give

_et
_ jM
n (M
)~al. 2013,
P(Mv )n(Mv ) dMv
Bouché
Science,341,
50
0Fig. 1. Emission and ab_ ), obtained by integ
The (A)
desired cumulative abundance, n(.Msorption kinematics.
Dekel et al. 2009, Nature, 457, 22_ to infinity, is shown at z 5 2.2 in
The color scale represents
over the inflow rates from M
a narrow-band image (rest_ , the curve referring to M
_ liesAssumingthat the SFR equals M
frame Ha) with thecontinuum subtracted from
our AO-the observed values, marked by the symbols, indicating th
above
assisted VLT/SINFONI datacube.
_ agas input
rate is sufficient to explain the SFR. However, M
The quasar HE2243–60
andare allowed to differ only by a factor of ,2, confirmin
the host z ~ 2.328 SFR
galaxy aremarked. The residuals
fromsuspicionthat the SFR must closely follow the gas input rat
the continuum subtraction are
simulated
SFR indeed traces the accretion rate to within a fac
visible both near thequasarand near the position
labeledtwo,but, given that our disks are poorly resolved, we focus h
R. The galaxy is detected
inthe accretionas the more robustly simulated quantity. Beca
Ha with a maximum SNRz<
2.2 the star-forming galaxies constitute only a fractionof ~5 to 8 per pixel;
no continuum emission isobserved
detected.
,1011M[ galaxies24,25, the requirement for a SFR a
The beam has a full width_ , based on Fig. 4, becomes even stronger.
great as M
at half maximumas(FWHM)
of ~0.25 arc sec. (B)By
Theanalysing the clumpiness of the gas streams, using thefitted velocity fieldpeaks(extrap-of inflow in the M_ (r) profiles, we address the role of molated over the entire field)
versusflows. We evaluate each clump mass by integ
is shown along withthe flux smoothÐ_ (r)=vr (r)) dr across the peak, and estimate a mas
contours. The kinematicpa- ~ (MMclumprameters were determined
for the expected merger as m 5 Mclump/fbMv, ignoring further
using our 3D analysis (17).
loss thein the clump on its way in and deviations of the galaxy b
The dotted line shows
kinematic major axis.
At the from fb. We use ‘merger’ to describe any major or
fraction
quasar location (solid circle),merger with m $ 0.1, as distinct from ‘smooth’ flows, which in
the rotation speed is expected
mergers with m , 0.1. We find that about one-th
to be ~160 to 180‘mini-minor’km s–1.
(C) The absorptionthe
profilesmass is flowing in as mergers and the rest as smootherfrom the VLT/UVES spectra
However, the central galaxy is fed by a clump with m $ 0.1 lesshowing the line-of-sight
10%ab-of the time; that is, the duty cycle for mergers is g =Figure 2 | Streams in three dimensions. The map shows radial flux
for thevelocityof the various

cold gas accretion

7第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Importance of Inflow and Outflow:

ERB

Vol. 674
closed-box

z~2.2

Metallicity• Metallicity also changes through gas infall/outflow process• Constraint on the inflow/outflow rate by using metallicity, gas fraction✓ e.g., Erb et al. 2006, Erb 2008 (z~2), Mannucci et al. 2009 (z~3)✓ A certain amount of inflow/outflow is required✓ Sample size, however, is still limitedz~3✓ Gas mass estimation is uncertain

Metallicity

Gas Fraction µ

Gas Fraction µ

Erb 2008, ApJ, 674, 151

Fig. 3.—Evolution of metallicity with gas fraction as described by eq. (11).
The data points indicate the metallicities and gas fractions found for z " 2 gal-

Figure 10. Mannucci
Metallicity (top) et
andal.
effective
yields(bottom) as a398,
functionof2009,
MNRAS,
1915
gas fraction. This is plotted decreasing rightwards, to have galaxies evolving第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

FMOS (Fibre Multi Object Spectrograph):• What is FMOS?

✓ Fibre-fed NIR multi-object spectrograph on the Subaru Telescope (8.2m)✓ Prime Focus Unit with fibre positioner “Echidna” (400 fibres, 30 arcmin Φ)✓ Two NIR (0.9 - 1.8µm) spectrographs (IRS1 & 2)
✓ Low Resolution (LR; R~650) and High Resolution (HR; R~3000) mode
✓ Details are presented by Kimura et al. 2010, PASJ, 62, 1135
Two NIR
spectrographs

Prime Focus Unit

Fibre cable

FMOS on the Subaru Telescope

Fiber positioner “Echidna”

Optical design of FMOS including OH-mask mirror

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Hα detected sample galaxies at z~1.4:• Target selection✓ K-band selected galaxies✓ 1.2<zphot<1.6, K<23.9 AB mag, M*>109.5 Msunexp>5.0x10-17 cgs✓ Expected Hα flux cut with F(Hα)3650
K. Yabe et al.
• Observations✓ (mainly) GTO time
✓ Low resolution (LR) mode
✓ λ coverage: 0.9 - 1.8 µm✓ Typical on-source exposure
all sample
time is 3-4 hours
target objects✓ Hα detections with S/N>3 from343 galaxies at z~1.4

Our sample is basically on
the SFR main sequence第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Gas Metallicity:• Gas metallicity is derived derived from [NII]λ6584/Hα line ratio• Empirical metallicity calibration with N2 index (Pettini & Pagel 04)• The mass-metallicity relation at z~1.4 (Yabe et al. 2012, 2014)✓ Most of our sample show nondetections of [NII] emission lines➡ stacking analysis✓ More massive galaxies showhigh metallicity (MZR)✓ Note that there exists a large
scatter in the relation

Thick solid line: regression line (this work)
Thin solid line: regression line (initial results; Yabe+12)

Yabe et al. 2014

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Stellar Mass, Gas Mass Fraction, and Metallicity:• Gas mass is derived from Hα luminosity (Kennicutt-Schmidt law)
• Galaxy size is defined by the half light radius in B-band (rest-UV)• Gas mass fraction is defined as: µ=Mgas/(Mgas+Mstar)• Galaxies with larger stellar mass tend to show lower gas mass fraction• Galaxies with lower gas mass fraction tend to show higher metallicity

Unobservable region
SFR(Hα)<10 Msun/yr

Unobservable region
SFR(Hα)<10 Msun/yr

(µ)
as below:@名古屋大学 2015/06/03-05
第2回 銀河進化研究会-metallicity relation at z ∼ 1.4 by using the simple analytical models with effects

Analytic Model of the Chemical Evolution:fiyInflow/Outflow
rateisconstrained
by
using
a
simpleanalytic model•Z
ow implemented(e.g.,
Matteucci
2001;
Erb−12008).
fi − fo −1
Z
=
{1
−
[(
f
−
f
)
−
(
f
−
f
−
1)µ
]
},
(2.5)
i
o“The chemicalio evolution of galaxies” (ASSL)
2001• c.f., Matteuccifi
the same
simple modelas Erbwe
08formulate
and Mannucci+09
used (Z) as a
• (Basically)
ordingto the notationby Matteucci(2001),
the metallicity• We assume both inflow and outflow rate is proportional to the SFR, i.e., theyield,
fi andfoisareinfalland outflow
in a unitrate
of is
SFR,
respectively.
HereinflowratedM
the outflow
dMout/dt=(1-R)foΦ(t),ass fraction(µ)
as
below:
in/dt=(1-R)fiΦ(t) and rate

where R is return fraction and Φ(t) is SFR.

tantaneous recycling approximation and the infalling gas is metal free. The gasfi
yZ−1 fi − fo −1
Z = of{1the− [(fi − fmassfi −fo − 1)µ ]},o ) − (ase written as a function
stellarfollows:fi

0 + ( f − f − 1)M
Mgas
i
o
∗
is a true yield,µ f=rate in a unit of SFR, respective
i and f o are infall and outflow
,
(2.6)
0
Mgas + ( fi − fo )M∗
med the instantaneous recycling approximation and the infalling gas is metal free.

where Z is the metallicity and μ is the gas mass fraction. M0gas is
ction
caninitial
be written
as aandfunctionof thestellarmass as follows:
itialtheprimordial
gas
mass.
gas
mass
M* is thestellarmass.

assumptions:estimated from Hα flux and sizeOtheroftheby assuming Kennicutt-Schmidt
0 + ( galaxy
M
f
−
f
−
1)M∗ Approximation (IRA)ioRecyclinggas
Instantaneous•= nThe, measured
0
nicutt 1998a) with an indexµof
=
1.4.
We
take
the
r
from K-band
initialgasisprimordial• Mgas + ( fi − fo )M∗ 50 (metal free)• The initial mass function (IMF) is constant in time
∼9000Å in the rest-frame, deconvolvedby thesize asintrinsic(yZ)seeing
is assumed
to thebe 1.5
Zsun size• The true yield第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:• Inflow/Outflow rate is constrained by using a simple analytic model• c.f., Matteucci 2001 “The chemical evolution of galaxies” (ASSL)• Gas mass fraction increases with increasing inflow at a fixed stellar mass
• Metallicity decreases with increasing inflow at a fixed gas mass fraction• Note that simple closed box models can not explain the observations
fo=1.0 (fixed)

Closed Box

fo=1.0 (fixed)第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:• Inflow/Outflow rate is constrained by using a simple analytic model• c.f., Matteucci 2001 “The chemical evolution of galaxies” (ASSL)• Gas mass fraction increases with increasing inflow at a fixed stellar mass
• Metallicity decreases with increasing inflow at a fixed gas mass fraction• Note that simple closed box models can not explain the observations
fo=1.0 (fixed)

Closed Box

fo=1.0 (fixed)第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:• We fit observations (M* vs. µ, µ vs. Z, M* vs. Z) by a simple
analytic model of chemical evolution• fin, fout, M0gas are free parameters

M* vs. gas fraction

gas fraction vs. Z

M* vs. Z

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:
χ2 contour mapof each fitting

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:
χ2 contour mapof each fitting

The joint constraint
by M* vs. μ plot andM* vs. Z plot.

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Inflow/Outflow Rate in galaxies at z~1.4:• We fit observations (M* vs. µ, µ vs. Z, M* vs. Z) by a simple
analytic model of chemical evolution• fin, fout, M0gas are free parameters• Note that the unit of fin, fout is “SFR [Msun/yr]”
M* vs. gas fraction

gas fraction vs. Z

M* vs. Z• The best-fit fin is 1.84
• The best-fit fout is 0.60

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Evolution of Inflow/Outflow Rate:• Comparison with studies at other redshifts from z~2 to z~0• Sample at z~0 by Peeples+11 (metallicity is taken from Tremonti+04)• Sample at z~2.2 by Erb+06• We see the evolution in each figure✓ Gas mass fraction decreases with decreasing redshift✓ Metallicity increases with decreasing redshift• We fit these observations at other redshifts in the same analytic modelM* vs. gas fraction

gas fraction vs. Z

M* vs. Z

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Evolution of Inflow/Outflow Rate:• Comparison of inflow and outflow rate with previous results• Inflow/outflow rate are all converted to “mass” rate in the unit of Msun/yr• Both inflow and outflow rates increase with increasing redshift• Inflow rate in this work well agrees with the models by Bouché+10• Outflow rate in this work well agrees with the past observations

MDH=2x1012 Msun

MDH=1011 Msun

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Total Mass Dependence of Inflow/Outflow Rate:• It is natural that the gas flow (esp. outflow) depends on the galaxy mass
• Two sub-samples according to the total (stellar + gas) mass
• The larger total mass shows the larger inflow/outflow rate?
• The trend is not so clear• Note that the trend reflects the correlation between mass and SFR?

Lager open symbols show
larger total mass
MDH=2x1012 Msun

MDH=1011 Msun

Lager open symbols
show larger total mass

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05(More) direct gas measurement with ALMA:• ALMA observations of 20 FMOS targets (Seko et al. in prep.)• Significant CO(J=5-4) detections from 11 objects• CO(J=1-0) conversion / metallicity dependent CO-H2 conversion factor• fi=1.7×SFR fo=0.4×SFR (from CO measurement)• fi=1.8×SFR fo=0.6×SFR (from Hα assuming KS law)
1.0
1.4
1.2

0.8

1.0

Z

fgas

0.6
0.8
0.6

0.4

0.4
0.2
0.2
0
1.0

Seko et al. in prep.
0.8

0.6

fgas

0.4

0.2

0

0

109

1010

M★

1011

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05(Larger) sample from FastSound survey:• Much larger NIR spectroscopic sample from FMOS FastSound survey• ~4000 Hα detections at z~1.4 (Yabe et al. 2015, submitted)• The mass-metallicity relation agrees with previous obs. (such as GTO)
• Similar analysis for inflow and outflow with this sample• Larger gas mass fraction compared to the GTO sample
M* vs. gas fraction

gas fraction vs. Z

Note that the FastSound sample
traces relatively higher SFR

M* vs. Z• The best-fit fin is 0.7-2.0• The best-fit fout is 0.0-1.0

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Gas Mass Fraction and Inflow/Outflow Rate:• Much larger NIR spectroscopic sample from FMOS FastSound survey• ~4000 Hα detections at z~1.4 (Yabe et al. 2015, submitted)• The mass-metallicity relation agrees with previous obs. (such as GTO)
• Similar analysis for inflow and outflow with this sample• Larger gas mass fraction compared to the GTO sample
FastSound
FastSound

MDH=2x1012 Msun

MDH=1011 Msun

第2回 銀河進化研究会 @名古屋大学 2015/06/03-05

Summary：• Inflow and outflow of gas play an important role in galaxy

formation and evolution• Constraints of the gas inflow and outflow rate by using stellar
mass, gas mass fraction, and metallicity at z~1.4✓ Fit with a simple analytic model of chemical evolution✓ The best-fit inflow rate is ~1.8 times SFR✓ The best-fit outflow rate is ~0.6 times SFR• The same analysis applied to the previous results at z~0 and z~2.2✓ The inflow and outflow rates increase with increasing redshift✓ The trend of redshift evolution of inflow and outflow rates isin good agreement with the previous observations and thetheoretical models• Analysis by using more direct gas mass estimation from ALMA
CO detected sample shows similar results• Larger sample from FMOS FastSound survey also shows similar
SFR normalized inflow and outflow rate, but slightly larger mass
inflow and outflow rate