ダークハローの平均面密度を用いたダークマター理論への新たな制限手法の提案
KH & Chiba 2015, ApJL, 803, 11 (arXiv: 1503.05279)

東京大学カブリIPMU (JSPS研究員)
林航平
共同研究者：千葉柾司 (東北大学)

⏎
␝
⏲
␗
ダクション
2015/6/3

第２回銀河進化研究会@名古屋大学

Cold Dark Matter theory~ small scale crisis ~v Cusp-core problem (Burkert+ 1995, Gilmore+ 2007)v Missing satellite problem (Moore+ 1999, Klypin+ 1999)v Too-big-to-fail problem (Boylan-Kolchin+ 2012, Garrison-Kimmel+ 2014 )N-body + Baryon feedback + UV backgroundcore-cusp

missing satellites

di Cintio+ 2014Sawala+ 20142015/6/3

第２回銀河進化研究会@名古屋大学

Too-big-to-failMadau+ 2014

Warm Dark Matter theory~ another possible solution ~ü WDM particles have a free-streaming motion,giving rise to a cut-off matter power spectrum
at larger wave number corresponding to small
spatial scale.

CDM
2015/6/3

WDM
第２回銀河進化研究会@名古屋大学

Constraints on WDM particle
mass from low mass scalesü With Lyman-alpha forest
first constraintNewestv
v

mWDM ≥ 0.75 keV
mWDM ≥ 3.3 keV(Narayan+ 2000)(Viel+ 2013)ü With Milky Way satellitesv Missing satellitesv
Too-big-to-failv LF & MW mass

mWDM ≥ 2.3 keV
mWDM ≥ 1.1 keV
mWDM ≥ 2.0 keV(Polisensky & Ricotti 2011)(Lovell+ 2012)(Kennedy+ 2014)

The above tests largely rely on the Mass of the MW halo,
where the estimate of the MW halo is still very uncertainty...

2015/6/3

第２回銀河進化研究会@名古屋大学

The purpose of this study
In an attempt to place an explicit constraint
on dark matter models, especially particle
mass of warm dark matter,
we define and estimate the mean surface
density of a dark halo with respect to various
galaxies, and compare it to predicted ones
from DM theories.
2015/6/3

第２回銀河進化研究会@名古屋大学

ー⏪

ー⏙⏹
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⎡ 平均面密度2015/6/3

第２回銀河進化研究会@名古屋大学

Dark matter surface density withina radius of maximum circular velocityü Maximum circular velocity

We suppose that a test particle perform
circular motion in a DM halo potential.

Vcirc

Vcirc

Vmax

rmax indicates the radius of the maximum
value of circular velocity, Vmax.

rmaxrü DM surface density within rmax

any DM profiles
2015/6/3

第２回銀河進化研究会@名古屋大学

Sample and assumed DM profile
Galaxy type

Assumed dark halo
profileReference

Late- and early-typespirals

pseudo-isothermal
profilede Blok+ 2008
Spano+ 2008

dwarf irregulars

Burkert profile

Gentile+ 2005, 2007

spirals and ellipticals

Burkert profile

Donato+ 2009

MW and M31 dwarf
spheroidals

double power law(any slope) profile

KH & Chiba 2015,
in prep

pseudo-isothermal
2015/6/3

BurkertDouble power-law

第２回銀河進化研究会@名古屋大学

DM surface density vs. Vmax
8dSphs (core) [This work]dSphs (cusp) [This work]
Spirals (THINGS)
Spirals (GHASP)
dIrrs
max
Spirals & Ellipticals

Dark matter surface density within r
isalmost constant across a wide range of galaxies,
4irrespective of dark halo density profiles.
-2log (YVmax) [Msun pc ]

6

20-2

2015/6/3

50

100

150

200
250
Vmax [km/s]

300

第２回銀河進化研究会@名古屋大学

350

400

450

ダークマター理論との比較
2015/6/3

第２回銀河進化研究会@名古屋大学

DM surface density from CDM and WDMØ Dark matter density profileØ Concentration
20

WDM: m=2keV
WDM: m=3keV
CDM1612Ø The scale density and scale radiusc(M)1086

CDM: Prada+ 2012
Klypin+ 2014
WDM: Schneider+ 20144108

Ø Mean surface density

2015/6/3

第２回銀河進化研究会@名古屋大学

1091010

1011

1012
1013
Mvir [Msun]

1014

1015

1016

Comparison with dark matter scenario

Warm dark matter scenario
is inconsistent with this constancy.

2015/6/3

第２回銀河進化研究会@名古屋大学

How cold is dark matter?
3σ error
5σ error

2015/6/3

第２回銀河進化研究会@名古屋大学

将来展望2015/6/3

第２回銀河進化研究会@名古屋大学

UFDs, dSphs

2015/6/3

第２回銀河進化研究会@名古屋大学

Future perspective ofdark matter halo in the dSphs
Subaru/HSC• Discovery of New UFD• Hunting a number of faint stars in
MW and M31 satellites

Subaru/PFS• Determining better radial
velocities for many faint stars overlarge area of dSphs via PFS withMR (R~5,000).

2015/6/3

第２回銀河進化研究会@名古屋大学

HSC survey for UFD satellites
Tollerud+ 2008

SDSS: ~ 22 mag
HSC wide field survey: rlim 〜 26 mag

2015/6/3

第２回銀河進化研究会@名古屋大学

PFS survey for dwarf spheroidal satellites
Walker et al. 2009tidal radius

PFS survey for dwarf spheroidal satellites
Takada et al. 2014

Subaru PFS pointingtidal radius

Summary
In order to be constraint on dark matter models, we define
and estimate the mean surface density of a dark halo within
the radius of maximum circular velocity, which is derivable forvarious galaxies with any dark matter density profiles.
• It is found that this density is nearly constant across a wide
range of galaxies, and this constancy is enable us to obtainthe limits on particle masses of WDM scenario.
• This study proposes a new astrophysical test on the nature ofdark matter.
• The key dark-halo mass range to distinguish dark mattermodels in this test is the lowest halo mass scales such asclassical and ultra faint dwarf galaxies.
•2015/6/3

第２回銀河進化研究会@名古屋大学

終2015/6/3

第２回銀河進化研究会@名古屋大学