Galaxy evolution workshop (2018)
Ehime University

Dust properties fromcosmological simulation
Shohei Aoyama
Academia Sinica (ASIAA)
Hiroyuki Hirashita, Wei-Hao Wang,Chen-Fatt Lim, Kuan-Chou Hou (ASIAA),
Kentaro Nagamine, Ikkoh Shimizu (Osaka University)
Aoyama et al. in preparation.

Introduction• Dust absorbs UV-optical light andreprocess it into the IR.
• IR luminosity function, Tdust and IRX-βUVindicate the dust abundance, distribution
and the interstellar radiation field.
C. Gruppioni et al.(2013)[1302.5209]• They are observationally obtained withmany ground observatory (e.g. JCMT) andsatellites (e.g. Herschel, Spitzer, IRAS) at
various redshift (0<z<4).
• Recently, STUDIES (JCMT/PI: Wei-Hao Wang) Slope β
UVrevealed the property of optically-faint, IRluminous and high-z objects.
1650 Å 2300 ÅIntroduction• Dust absorbs UV-optical light andreprocess it into the IR.
• IR luminosity function, Tdust and IRX-βUVindicate the dust abundance, distribution
and the interstellar radiation field.
C. Gruppioni et al.(2013)[1302.5209]• They are observationally obtained withmany ground observatory (e.g. JCMT) andsatellites (e.g. Herschel, Spitzer, IRAS) at
various redshift (0<z<4).
• Recently, STUDIES (JCMT/PI: Wei-Hao Wang)
revealed the property of optically-faint, IRluminous and high-z objects.
LUV(1650)=c/1650[Å]FνSimulation (Aoyama et al. 2018 MNRAS accepted)[1802.04027]• Cosmological hydro-dynamical simulation
with dust evolution is performed byGADGET3-Osaka.
• Boxsize: 50 Mpc/h• Resolution: 3 ckpc (2×5123)• Dust size distribution is represented asHirashita (2015).
• Not only dust production and growth(accretion)
but also dust-dust interaction(coagulation and shattering).

In this work, we use
the GADGET3-Osaka SPH code(Springel ‘05 + modification).

i-th SphL↗

atoms,molecules

grain growth
S↗

dust

coagulation

SNe II
SNe IaAGBSaitoh (2017)

SN shocks
L→×, S→×

Mg , Zi ,Ti,ψi etc.

L↘:-(ML/Mg)ψ
S↘:-(MS/Mg)ψ

shattering

Figure credit :AsanoMass Fcn and dust radial profile• Hydro-dynamical simulation with dust
evolution is performed byGADGET3-Osaka.
• Dust size distribution is represented as
Hirashita (2015) and not only dust
production and growth (accretion)
but also dust-dust interaction(coagulation and shattering).
• We successfully reproduce the dust
mass function and radial profile of dustetc.

Mass ftn. z=2.5

z=0Radial profile ofdust grains

Modeling of dust absorption and emission• We estimate the radius of IR emitting region Rdustby performing the exponential fitting of radial
profile of dust mass density.
• We take into account stars and dust grains at
0 < 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.

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

• From the LF, we cannot say anything
about individual galaxies,
so this statement is irrelevant.

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

IRX-βUV relation at z=0• Observational points are shownas stars(☆: Meurer et al. 1999) andcross(×: C.M. Casey et al. 2014).
• We predict observational sequenceand the scatter.
• Affected by the assumed geometry ofdust distribution. -> screen geometry
could disperse these points.
Blue line : Star forming galaxies: Meurer et al. (1999)

STUDIES (SCUBA2)
W-H. Wang et al. (2017), C-H. Lim in prep.
• λ=450, 850 μm• Survey area: COSMOS-CANDELS region (151 arcmin2)• Noise level 0.91 mJy
Taking advantage of the large aperture,
fainter objects which Herschel cannot detect
can be observed.
• The integrated surface brightness down to1mJy can account for up to 83+15-16 % of
COBE background.
W-H. Wang et al. (2017)

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 still up to z≃2.
• It means that we cannot reproduce
compact star burst at high-z.

Solid L50N512 (Default)
Dashed L25N512• Neglecting AGN heating does not makethis difference.
(e.g. Y-Y. Chang et al. 2017,
C. Gruppioni et al. 2013 )“Maximum” stellar mass in this simulationtff ≃ 1.0 ×107 yr• When we consider a situation that all gas particles bounded in IR emitting region areconverted into star particles within dynamical time scale.
• Because of the resolution (≃0.3 comoving kpc), only 37 particles can be packed within
IR emitting region (≃1kpc: S. Fujimoto 2017) at z=3. Thus created star mass becomes
7.0×108 M☉ ( the age ≃ 1.0 ×107 yr ).
• According to SED table (Bruzual & Charlot 2003), the luminosity becomes 2.5×1011L☉.

“Maximum” stellar mass in this simulationtff ≃ 1.0 ×107 yr• Particle-based simulations with the finite resolution (0.3 ckpc)
have the luminosity limit (2.5×1011L☉).
Cf. a theoretical limit (Eddington limit) 1013 L☉kpc-2 (R. M. Crocker et al 2018)

Tdust-LIR@high-z universe
log10(Mdust/M☉)• Our prediction is located at luminous end
around the center of the observational
data points.
• In dusty galaxies, dust temperature
becomes low because of increase of dust
to stellar mass ratio.
• Because of lacking of star bursts,
we cannot produce luminous enoughgalaxies at high-z.

IRX-βUV@high-z universe

βUV: Slope ofSED at UV

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

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

Summary• We analyze our simulation results (Aoyama et al. 2018) andobtained IR luminosity function, dust temperature and IRX-βUV relation.
• At z=0, our simulation can explain IR luminosity function, dust temperatureand IRX-βUV relation.
• At high redshifts, they are not explained by our simulation because of alacking of star bursts due to basically resolution limit.
• However our treatment of dust extinction and IR emission works wellwhen we compare the observation data (STUDIES).