Comparison of cosmologicalsimulations anddeep submillimetre galaxy surveys
Shohei Aoyama (青山尚平)

Academia Sinica
Institute of Astronomy and Astrophysics
Based onAoyama et al. (2018) MNRAS, 478(4), 4905 [1802.04027]-> Aoyama et al. (2019) MNRAS, 484(2), 1852 [1809.10416]

Importance of dust grains• Spectrum energy distribution (SED)
Infraredis significantly modified by dust.

Infrared• The modification is determined by
dust spatial and size distribution
in the galaxy.

(24μm)

visibleSED

SED of M31

Groves+2012• Not only spatial but also grain sizedistribution have to be predicted
theoretically in order to estimate
the star formation activity.

Size distribution treatment
Hirashita 2-component model [1412.3866]

Size distributionn(a)0.03 μma

Research theory

simultaneously

Surface density

Galaxy evolution
Gas physicalcondition(density fieldρ,temperatureT,Star Formation)• Hydrodynamics of gas and starformation are treated consistently
with the gravitational evolutions ofdark matter, etc.
• Formation of metals (ingredient ofdust) is treated according to thestar formation history.

Dust model

Size distribution

0.03μma• Dust evolution is calculated by local
density, temperature anddust abundances.
• Accretion, coagulation, (growth)
shattering (destruction)
are implemented.

Simulation• Cosmological hydro-dynamical simulation
with dust evolution (Hirashita model ‘15)
is performed by GADGET3-Osaka.
• Star formation, early stellar and
SNe feedback are consistentlyimplemented.
• Planck cosmology (2015)• Boxsize: 50 Mpc/h• Resolution: 3 ckpc
• # of particles : 2×5123

Rapid growth★: Observation(Remy-Ruyer+14)

Metallicity Z(ingredient of dust)

log10(Mstar/M☉)

Dust-to-gas mass ratio log10(Dtot)

Results 1. Dtot-Z relation @ z=0• Dust production is strongly associatedwith metal enrichment.
The relation gives a strong test for dustevolution models.
(Lisenfeld & Ferrara 1998; Dwek 1998)• We reproduce the rapid growth of dust
at Z/Z☉ ~ 0.1.
Dust growth in ISM is confirmed to be
successfully implemented.

Dust surface density

Results 3. large scale distribution of dust
• Large scale distribution of dust reflects
dust transport (stellar energy input) anddust evolution (especially, dust● Observation(Menard+10)
destruction in the hot gas in the galaxyhalo).
Model(our work)
Model(a previous work)• Our model describes roughly observational
one within 0.5 dex at r > 30 kpc.

• We succeeded in reproducing dust
distribution in cosmological scale :Distance from a center galaxy r our consistent treatment ofstellar energy input and dust evolution
is essential.

z≃7の宇宙 simulation with Hirashita15 model

1天体
1個/(50Mpc/h)3

Introduction
Key quantities• IR luminosity function LIR(LIR, z)• Dust temperature Tdust•(the ratio of IR to UV.)

• Slope of SED at UV @2000Å βUV

C. Gruppioni etal.(2013)[1302.5209]

Infrared galaxies in the simulations• We predict observed quantities related to dust grains (IRluminosity function, IR-βUV relation etc. ) at high-z Universe bysimulations and reveal which processes are important forexplaining observations.
• By comparing the predictions and corresponding observations andfinding the discrepancies between them, we identify the reasonsand try to improve the simulations and models.

Modeling of dust absorption and emissionlog10(ρdust)• We estimate the radius of IR emitting region
Rdust by performing the exponential fitting ofradial profile of dust mass density.
• We take into account stars and dust grains at0 < R < Rdust .
• The intrinsic SEDs of stars are estimated bytheir age and metallicity based on
Bruzual & Charlot (2003).
• The extinction is estimated based on
the mixed geometry.

Rdust=2/αR

Luminosity function at z=0
Gray shaded region: Herschel satellite
C. Gruppioni et al.(2013)• We compare the LF with observation
result with Herschel.
• Overall statistics is consistent withobservation.

Luminosity function at z=0
Gray shaded region: Herschel satellite
C. Gruppioni et al.(2013)• We compare the LF with observation
result with Herschel.
• Overall statistics is consistent withobservation.

Tdust-LIR at z=0• Dust temperature is estimated by[K]• Reproduced Tdust—LIR relation●: M. S. Clemens et al. (2013)▼: A. Amblard et al.(2010)▲: J. A. Zavala et al. (2018)• It indicates that our dust model
describes the IR luminosity and the dust
optical depth (or dust surface density)
consistently.

IRX-βUV relation at z=0• Observational relation are shown(dot-dashed; Kong et al. 2004,solid line; Takeuchi et al. 2012).
• We predict observational sequence.
• Affected by the assumed geometry of
dust distribution. -> screen geometry
could disperse these points.

STUDIES (SCUBA2)

W-H. Wang et al. (2017), C-H. Lim in prep.
• λ=450, 850 μm• Survey area: COSMOS-CANDELS region (151arcmin2)• Noise level 0.91 mJy• Taking advantage of the large aperture,
fainter objects which Herschel cannot detect
can be observed.
• Large survey area and 2 wavelengths.
• The integrated surface brightness down to1mJy can account for up to 83+15-16 % of
COBE background.

JCMT

https://en.wikipedia.org/wiki/
James_Clerk_Maxwell_Telesc
opeLuminosity function @high-z universe• Our snapshots are consistent withobservation only at z≲1.
• When we performed a simulation
whose spatial resolution is 2 times
better, we can explain LF stillup to z≃2.

Solid L50N512 (Default)
Dashed L25N512• Hence resolution is not the reason forlack of IR luminous objects.

IRX-βUV@high-z
universe

βUV: Slope ofSED at UV@2000Å

log10(LIR/L☉)• IRX-βUV relation are explained bysimulation results up to z≃3.
Dust abundance and extinction are
successfully treated even at highredshift (z ≲ 3).

• The observation uncertainty of βUVbecomes large because the targets areoptically faint.
• At z≃4, some galaxies whose SEDs
are very red cannot be explained.

Extra dust heating from SMBHs

BHLEddAdditionalheatingsource
Galaxy withdust grains

Haering & Rix (2004) [astroph/0402376]• We assigned the super massive black
holes randomly to identified galaxies.
• The mass is estimated by Magorrianrelation (Haring & Rix (2004))• The luminosities of SMBHs aresupposed to be Eddington luminosity.

• The energy from SMBH is assumed tobe completely absorbed by dust grains

Additional heating of dust grains by AGN• We post-processed theadditional dust heating fromSMBHs. Maggorian relation(Haring & Rix (2004)) andEddington luminosity isassumed. All photons areabsorbed by dust.

Red : w/ AGN heating
Blue: w/o AGN• Almost all data points can be
explained by AGN heating evenin the high-z galaxies even atz>2.

Summary• We analyze our simulation results (Aoyama et al. 2018a) andobtained IR luminosity function, dust temperature and IRX-βUV relation.
• At z=0, our simulation can explain IR luminosity function, dust
temperature and IRX-βUV relation.
• At high redshifts, abundance of high luminous objects cannot beexplained.
It is not related to spatial resolution of simulations very much.
(additional dust heating by AGN?)• Our treatment of dust extinction and IR emission works wellwhen we compare the observation data (STUDIES) in terms of IRX-βUV.