Transcript The Origin and Evolution of Dust in Galaxies

Origin and evolution of dust in galaxies
Spitzer Observations of Dust
in the Local Group Galaxies
Implications for dust in high-z galaxies
Mikako Matsuura
Origin’s fellow, Institute of Origins, University College London
Team

Mikako Matsuura
 Eric Lagadec
 Karl Gordon

M. J. Barlow
 Quentin A Parker
 Remy Indebetouw

Greg Sloan
 Warren Reid
 Ciska Kemper

Kevin Volk
 Takashi Shimonishi
 Massimo Marengo

Jeronimo Bernard-Salas  E. van de Are

Tom Llyod-Evans
 H. van Winkle
 Xander Tielens

You-Hua Chu
 Peter Wood
 Jacco van Loon

Robert Gruendl
 Albert Zijlstra
 Paul Woods

Bruce J. Hrivnak

Yoshifusa Ita

Kathleen Kraemer
The orign and evolution of dust in galaxies
 Margaret Meixner
Log (λ * Lλ) (L)
Introduction: IR emission
 What is the origin of dust?

Origin/quantity

0.1
1
10
100
Wavelength (micron)
Da cunha et al. (2008)
1000
Infrared

 Infrared (IR) emission of
galaxies
 Thermal emission from dust grains
 Indicator of starformation rate
The orign and evolution of dust in galaxies
Can we account for dust
mass in the interstellar
medium (ISM) by stellar
sources?
Effects of different
metallicities


Dust compositions
Dust formations
 Origin and quantity
 Effects of metallicities
 Dust compositions
 Dust formation
 Implication for the distant galaxies
Cycle of matter (gas and dust) in
galaxies
Important for galaxy
evolution
Concept of cycle of matter
Past: Theory/models
(population synthesis/chemical
evolution models of galaxies)
1- 8(10?) M
>8(10?) M
Current: measurements of dust
The orign and evolution of dust in galaxies
Large Magellanic Cloud (LMC)
 One of the nearest galaxies

50 kpc
 Spitzer Space Telescope
observations


Spectroscopic survey
Photometric survey 3.6-160 micron


3.6 micron: blue
8.0 micron: green
24 micron: red
Entire census of AGB stars
C.f. projection problem of the Milky Way
Optical image
Spitzer Space Telescope
Spitzer image (SAGE)
The orign and evolution of dust in galaxies
Analysis (1) : selection of dust
forming AGB stars
AGB stars are
the brightest
population in
mid-infrared
Foreground stars
AGB stars
HII regions / YSOs
Distant galaxies
Emission line objects
(WR stars)
Mid-infrared color magnitude
diagramme [8.0] vs [3.6]-[8.0]
The orign and evolution of dust in galaxies
Matsuura et al. (2009, MNRAS 396, 918)
Analysis (2) estimate of gas and dust
lost from individual AGB stars
 Detailed analysis of 40 AGB
stars provides dust/gas
mass-loss rate rate (M yr-1)
 JHKL photometry
 Spitzer spectra (5-35 micron)
 Spectral energy distributions are
fitted, using radiative transfer
code
Dust mass-loss rate: 3.1x10-8 M yr-1
Log dM/dt=
-6.2/[([3.6]-[8.0])+0.83]-3.39
Evolution of dust in galaxies
Analysis (3) : measured their gas and dust
mass-loss rate from IR data
Carbon-rich
Oxygen-rich
Sources
AGB stars
AGB stars
Gas
(10-2 Msun yr-1)
Dust (10-5
Msun yr-1)
2-4
(total)
5-11(total)
Dust species
Carbon-rich
4-8
Amorphous carbon,
SiC, PAHs
Oxygen-rich
1.5-3
Silicate
Detecting dust-embedded AGB stars using Spitzer
The orign and evolution of dust in galaxies
Matsuura et al. (2009, MNRAS, 396, 918; in preparation)
Gas feedback in the LMC
 Total AGB mass-loss rate: 2-4x10-2 M yr-1
 Oxygen-rich + carbon-rich AGB stars
 Type II SNe: 2-4x10-2 M yr-1
 In the LMC, Type II SNe and AGB stars are both important
gas sources
AGB
2-4x10-2 M yr-1
Evolution of dust in galaxies
Type II SNe
2-4x10-2 M yr-1
Gas budget of the LMC
•
•
•
•
Star formation rate (SFR) > Gas injection rate from SNe and AGB
LMC star formation depends on the large reservoir of existing ISM gas
The LMC is getting gas poorer. The SFR is likely to be declining with time.
Chemical evolution of the LMC ISM is very slow process (~1 Gyrs)
– ISM gas : 8x108 Msun (HI + H2) = Gas injection rate (0.03-0.08 Msun yr-1) x 1 Grys
Star formation rate
0.2-0.3 M yr-1
Evolution of dust in galaxies
ISM gas
8x108 M
SNe +AGB
0.03-0.08 M yr-1
Global dust budget in the Large
Magellanic Cloud
 Missing dust input problem in the LMC!
 Current LMC dust mass: 2x106 M


HI+H2 gas mass (8x108 M) x dust-to-gas ratio (0.0025)
(>0.9x106 M; Meixner et al. 2010 from Herschel observations)
 Dust injection rate from AGB stars: 5x10-5 M yr-1 (up to 11x10-5 M yr-1)

requires>20 Gyrs

Dust lifetime was estimated to be 4-8x108 yrs (Jones et al. 1994)
Lifetime of the LMC (~15 Gyrs)
 Dust deficit is short by a factor of 30
SNe
Dust formation?
(40-80000) M
Shock destruction?
AGB dust
(2-9)x104 M
over (4-8)x108 years
ISM dust
2x106 M
The orign and evolution of dust in galaxies
Other dust sources are
needed
Solutions for the dust deficit?
 Lower SN dust destruction Ifrate
dust mass increases in starforming
 Dust from high mass stars regions
 Higher SNII dust production
rate
Gas-to-dust
ratios
 Herschel measured dust mass of
0.075
in Galactic
SNR Cas A
in ISM
< Msun
in stars
(AGB, SNe)
(Barlow et al. 2010)
 Consistent with values used in our
LMC study
Herschel/ALMA
 Dust formation in LBV and WR stars
 Unaccounted dust mass in AGB stars?
 Dust mass increases in ISM
 External dust sources
The orign and evolution of dust in galaxies
 Origin and quantity
 Effects of metallicities
 Dust compositions
 Dust formation
 Implication for the distant galaxies
Dust compositions
 Targets
 Polycyclic Aromatic
Hydrocarbons (PAHs) in
post-AGB stars
Blocker (1995)
The orign and evolution of dust in galaxies
Difference between Galactic
and LMC post-AGB stars:
unique PAH features
PAH templates from
Galactic objects (Peeters
et al. 2002)
Spectral types of the
central stars
B
A
F,G
The orign and evolution of dust in galaxies
LMC metallicity
~half of the solar metallicity
New type, D
LMC post-AGB stars which do not fit
to Galactic PAH templates (type A-C)
No Galactic counterparts found so far
Matsuura et al. to be submitted
Origin of new type of PAHs
Origin of type-D PAHs
Mixture of lab data
Quartet
(four –H attached to a ring)
(Hudgins and Sandford 1998a, b)
Compact round-shaped PAHs
(no quartet)
Origin of different spectral shapes of PAH features in the
LMC stars from Galactic counterparts
- Different structures of PAHs
- Reason?: Lower density to prevent collisions between
PAHs?
The orign and evolution of dust in galaxies
 Origin and quantity
 Effects of metallicities
 Dust compositions
 Dust formation
 Dust in different environment: low-metallicity galaxies
 Bridging local group galaxies to high-z galaxies
 Implication for the distant galaxies
Can dust be formed at low metallicities?
Dust needs (astronomical) metals!
 Carbonaceous dust
 Oxides
 Olivines : Mg2xFe(2-2x)SiO4
 Pyroxenes : MgxFe1-xSiO3
 Graphite : C
 Amorphous : C
 Polycyclic aromatic hydrocarbons
(PAHs)
Dust mass : as a function of metallicity of galaxies
It has been suggested that it is difficult to form dust grains in
stars in low metallicity (Z<0.1 Z) galaxies
But … we found unexpected results
The orign and evolution of dust in galaxies
The Galaxies of the Local Group
Some galaxies have low metallicities
Sculptor dwarf spheroidal (dSph) galaxy
[Z/H]~-1.33
The orign and evolution of dust in galaxies
Fornax dwarf spheroidal galaxy
[Z/H]~-1.0
Spitzer spectra
SiC
Amorphous Carbon
Sculptor dSph galaxy [Z/H]~-1.33
Sloan, Matsuura et al.
(2009, Science 323, 353)
Fornax dSph galaxy [Z/H]~-1.0
Matsuura et al. (2007, MNRAS 382, 1889)
Contrary to expectation, we detected dust at low metallicities
The orign and evolution of dust in galaxies
Dust at low metallicity
AGB stars
 We detected amorphous (+SiC) dust
 Carbon atoms synthesized in AGB stars
 Dust formation process
around stars is affected
 not only by the metallicities of
the parent galaxies
 but also by elements formed
inside stars, in particular,
carbon
 Amorphous carbon, PAHs
(Our Galaxy)
(Fornax and Sculptor
dSph galaxies)
The orign and evolution of dust in galaxies
 Dust grains are formed
around the first generation
of AGB stars
Matsuura et al. (2005 A&A 434, 691)
 Origin and quantity
 Effects of metallicities
 Dust compositions
 Dust formation
 Implication for the distant galaxies
Implications for high-z galaxies with
dust
(Before our study)
Galaxies in the Local Group
High-z galaxies
Dust sources:
SNe (>8 Msun)
Assumed to be low
metallicity initially
z~6.4; ~0.4 Gyrs
(e.g. Bertoldi et al. 2003)
The orign and evolution of dust in galaxies
Dust sources:
AGB stars +
SNe
AGB + SNe
Metallicity
About solar metallicity
Dust can be formed in AGB stars and SNe
even at low metallicity
AGE
10-15 Gyrs
Age of AGB stars is much younger than previously
thought (starting 50 Myrs; Vassiliadis & Wood 1993)
Sloan, Matsuura et al. (2009, Science, 323, 353)
Hi-GAL
The Herschel infrared Galactic Plane Survey
Heritage
HerMES
HERschel Inventory of The Agents of Galaxy
Evolution: the Magellanic Cloud Survey
The orign and evolution of dust in galaxies
Dust grains
We found dust grains in many
galaxies …
But still we don’t know where
they are from.
The orign and evolution of dust in galaxies
Summary
 Low- and intermediate-mass stars are important dust sources
 But still found deficit in dust budget in the LMC
 Solutions will be tested using Spitzer/Herschel observations
 Dust from AGB stars are more carbon-rich, and contain more PAHs at
lower metallicity <-> ISM: weak PAHs
 High UV radiation in the ISM at low metallicity destroy PAHs
 Better constrains of age of dust forming stars required
 High-z galaxies
 Lower metallicities do not hamper dust formation in AGB stars
 Origins of dust in high-z galaxies are still open question.
 Dust mass in high-z galaxies may be explained, if both SNe and AGB stars
contribute dust formation
The orign and evolution of dust in galaxies