Host dark matter halos and galaxiesof z~6 quasars
Kazuhiro Shimasaku (UTokyo)
Co-I: Takuma Izumi (NAOJ)
ApJL,872,L29 (2019)

Introduction
Halo mass estimationz~6 quasar sample
Results
Summary2

Introduction
Halo mass estimationz~6 quasar sample
Results
Summary3

SMBH-galaxy correlations at z=0 suggest co-evolution

BH mass vs velocity dispersion

bulge mass [M]

velocity dispersion [km/s]

BH mass [M]

BH mass vs bulge mass

McConnell & Ma 2013, ApJ, 764, 184

4

BH mass vs stellar mass at z~6BH mass [M]

Majority of SMBHs seem to growearlier at z~6Izumi+18
Izumi+19
othersProblems:- not stellar mass but total mass of[CII]-detected area
- direct stellar mass estimation ishindered by quasar component

stellar mass [M]
data taken from Izumi+195

This study
BH mass vs dark halo mass for z~6 quasars
Why dark halo mass?
- maybe more reliable than stellar mass estimates- controls SMBH and galaxy evolution
Why z~6?
- earliest evolution accessible- easier than lower z thanks to [CII]158umWhy quasars?
- at z>0, BH masses can be obtained only for quasars
Why no previous studies?
- no method to individually estimate halo masses for quasars
6

BH mass [M]

What we want to know at z~6

SMBHs
grow earlier

lacoe
lrl

iotan

dark halos
grow earlier
dark halo mass [M]

7

Introduction
Halo mass estimationz~6 quasar sample
Results
Summary8

Estimating halo mass from [CII] velocity width[CII]158μm: from cool ISM; accessible at z>4.5

step 1. Rotation velocity from FWHM (Wang+13)
Vrot = 0.75 FWHMCII / sin i(i = cos 1 b/a, i = 55 if no b/a)

step 2. Flat rotation assumption[CII] disk of host gal

Vcirc = Vrot

Vrot

step 3. Spherical collapse model

dark halo

Mh = Mh (Vcirc , z)

Mh (Vcirc )9

Validation with clustering-based halo mass
15 z=2.7 QSOs with FWHMCO data and clustering-based Mh

BH mass [M]

(Trainor & Steidel 12, Hill+19)

clustering(median)

FWHMCO(individual)

Median halo mass [M] :clustering: log Mh = 12.30.5
FWHMCO : log Mh = 12.7 (N=9)
Uncertainty in our method:
Mh . 0.5 dex

sys: <0.4 dex overestimate
rand: 0.3 dex
1011

1012
1013
halo mass [M]

1014
FWHM[CII] ' FWHMCO for z ⇠ 6 QSOs
10

Introduction
Halo mass estimationz~6 quasar sample
Results
Summary11

Sample52 quasars with FWHMCII and MBH
redshift

All data from literature (eg, Decarli+18)
7 faint objs from Izumi+18,19
FWHMCII
46: ALMA
6: IRAM

M1450

MBH
23: virial method
29: Eddington accretion assumed
b/a available for 44 objs

12

Introduction
Halo mass estimationz~6 quasar sample
Results: Mass vs mass
Summary13

BH mass vs halo mass at z=01011

data points: Kormendy & Ho 13
line: Ferrarese 02

BH mass [M]

1010
109
108
107
106

1011

1012
1013
halo mass [M]

1014
14

BH mass vs halo mass for z~6 quasars
1011

z~6bright
faint Izumi+18
faint Izumi+19

BH mass [M]

1010

virial, b/a
Edd, b/avirial, i=55
Edd, i=55109

1−3dex overmassive

108
107

0.4% of baryons arein SMBHs (median)

106

Large scatter1011

1012
1013
halo mass [M]

1014
15

Lower-z quasars/AGNsz~2-5

1011z~0

BH mass [M]

1010109)
ing +19r
ste karulc han(S108107
106

FWHM(CO)FWHM(CO)

1011

1012
1013
halo mass [M]

1014

1011

1012
1013
halo mass [M]

1014
16

halo mass [M]

Another view of lower-z quasars
z~2-3 points: FWHMCO
pink bars: clustering (eg, He+18)
lines: DH mass growth models
dashed: Behroozi+13
dotted: Fakhouri+10

BH / haloQuasars are downsizing?

17Introduction
Halo mass estimationz~6 quasar sample
Results: BH accretion rateSummary18

BH accretion rate vs baryon accretion rate and SFR
BHAR vs BAR

BHAR vs SFRobjs with virial MBH and LIR(open circle: SFR upper limit)
BHAR (BH Accretion Rate)= dMBH/dt, from LUV

local MBH-Mh

local MBH-Mbulge

BAR (Baryon Accretion Rate of DH)= (Ωb/ΩM)dMh/dt, from N-body
SFR from LIR

BHAR ~ 10%SFR ~ 1%BAR
Much higher BH accretion rates than- local MBH/Mh and MBH/Mstar- time average (estimated at z<4)19Introduction
Halo mass estimationz~6 quasar sample
Results: Host galaxies
Summary20

Stellar masses and SFRs of host galaxies

z~6 average gals

halo mass [M]

star formation rate
star formation rate [M/yr]stellar mass [M]

stellar mass

Izumi+18
z~6 average galsIzumi+19
othersbaryon accretion rate [M/yr]

Many hosts are roughly average galaxies
21

Introduction
Halo mass estimationz~6 quasar sample
Results: Comparison with cosm. simulations
Summary22

EAGLE (Rosas-Guevara+16,MNRAS,462,190)
seed mass = 1.5105 M , Vol = (100cMpc)3

shaded: 10-90% tiles
circles: individual objs

our sample

23

MassiveBlack II (Khandai+15,MNRAS,450,1349)
seed mass = 5105 M , Vol = (142cMpc)3
our sample

Cannot produce observed massive SMBHs.
Larger simulation volume needed for meaningful comparison.

24

n(>M) h3 Mpc-3

Dark halo mass function at z~6n(>1e+12 Msun)~ 1e−5 /Mpc3

hmfcalc

mass rangeof our sample

dark halo mass [Msun/h]25

Introduction
Halo mass estimationz~6 quasar sample
Results
Summary26

SummarySMBHs in z~6 luminous quasars are growing earlier thanhost dark matter halos.
Order 1% of baryons in dark haloes are in SMBHs.
Large fraction of host galaxies are average galaxies
in terms of star formation (and perhaps stellar mass).
Future work:- Further tests of our Mh estimation method- Comparison with large-volume SMBH formation models- Some constraint on seed BHs?
Intrinsic limitation:- Quasars are outliers27