Starburst galaxies at low and high redshift Paul van der Werf Sterrewacht Leiden ESO, Santiago April 2006
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Transcript Starburst galaxies at low and high redshift Paul van der Werf Sterrewacht Leiden ESO, Santiago April 2006
Starburst galaxies at low and high
redshift
Paul van der Werf
Sterrewacht Leiden
ESO, Santiago
April 2006
Credits
starbursts at low redshift
starbursts at high redshift
Leonie Snijders (VISIR)
Liesbeth Vermaas (SINFONI)
Kate Isaak (Cardiff)
Padelis Papadopoulos (ETH Zürich)
Kirsten Kraiberg Knudsen (PhD October 2004)
Tracy Webb (McGill University, Montreal)
Lottie van Starkenburg (SINFONI)
and the FIRES team:
Marijn Franx
Pieter van Dokkum (Yale)
Ivo Labbé (Carnegie)
Greg Rudnick (NOAO)
Hans-Walter Rix (MPIA)
Mariska Kriek
Natascha Förster Schreiber (MPE)
Alan Moorwood (ESO)
Starburst galaxies at low and high redshift
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« The stellar systems are scattered through space as far
as telescopes can penetrate. We find them smaller and
fainter, in constantly increasing numbers, and we know
that we are reaching out into space, until, with the
faintest nebulae than can be detected with greatest
telescopes, we arrive at the frontiers of the known
Universe. »
Edwin Hubble, The Realm of the Nebulae (1936)
Starburst galaxies at low and high redshift
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What is a starburst galaxy?
A starburst galaxy is a galaxy with such a high star formation rate
that it will turn all of its gas into stars in tb << tHubble
Milky Way:
M H2
M
tb
2.5 109 M
1M yr 1
22
correction factor for mass return from stars
M H2
M
M H2
1010 yrs
0.5M gas
gradual buildup of disk
Starburst galaxies at low and high redshift
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A luminous infrared galaxy: the Antennae
Crossing orbits give
gas concentration in
interaction zone
Intense obscured
star formation in
overlap region
SCUBA 850 mm
Most intense star
formation is obscured
LFIR
M
3 1011 L
30M yr 1
(Webb, Snijders & Van der Werf , in preparation)
Starburst galaxies at low and high redshift
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An ultraluminous infrared galaxy: Arp220
LFIR
M
1.5 1012 L
150M yr 1
Starburst galaxies at low and high redshift
Arp220
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Starformation in ULIRGs
Arp220:
1.6 1010 M
M H2
M
150 M yr 1
tb
2
M H2
M
2 108 yrs
NB: tb few 108 yrs merger timescale
dynamical timescale
(crossing/rotation time)
free-fall time protogalaxy?
Such high SFRs can build up an entire
galaxy in t << tHubble
relation to galaxy formation?
correction factor for
mass return from stars
Starburst galaxies at low and high redshift
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Simple-minded estimate of
"maximum star formation rate"
In the absence of external pressure, the maximum star formation rate occurs
when a gas mass is turned into stars on the free-fall timescale.
M max
M gas
tff
M gas G
selfgravitating sphere: R
M max
G
2
2
3
4
100
M
100 km/s
3
yr 1
initial starburst – rapid formation of bulk of the stellar population
formation of spheroids?
Implication: high SFRs are found in the most massive galaxies
Starburst galaxies at low and high redshift
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Do “maximum starburst” galaxies exist?
ultraluminous IR galaxies
(ULIRGs)
maximum
starbursts
luminous IR galaxies
(LIRGs)
normal galaxies
(Kennicutt 1998)
Starburst galaxies at low and high redshift
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ULIRGs as “maximum starbursts”
M
A 10
M yr 1
10
ULIRGs (Lbol 1012 L ) have M
A f (IMF parameters) 1
M max!
ULIRGs
Lbol
L
LFIR
At L 10 L is
90%
Lbol
(cf., 30–50% for normal spirals)
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Starburst galaxies at low and high redshift
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Starformation efficiency
Starbursts cannot
be simply scaled up.
More intense starbursts
are also more efficient
with their fuel.
ULIRGs:
LFIR
M H2
LIR/LCO
SFR/MH2
100 L M 1 SFE
Milky Way:
1.5 L M 1
Galactic GMCs:
1.8 L M 1
OMC-1:
54 L M 1
Orion BN-KL:
(Gao & Solomon 2001)
LIR SFR
400 L M 1
Starburst galaxies at low and high redshift
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Role of dense gas
LIR/LCO
SFR/MH2
SFE
(Gao & Solomon 2001)
LHCN/LCO mass fraction of dense gas
More dense gas means more efficient star formation.
Starburst galaxies at low and high redshift
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NGC 4038/4039
NGC 4038/4039 detail
Superstarclusters:
does size matter?
NGC4038/4039 cluster:
100 pc
Orion:
1.5 pc
Orion (M42)
Starburst galaxies at low and high redshift
30 Doradus
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Superstarclusters: densities
nH
[M pc—3] [cm—3]
in 4.5pc in 4.5pc
5200
1.6∙105
Object
d
[pc]
M
[M]
[W99]2
100
2∙106
R136
10
3∙104
80
2500
M42
2
1800
5
200
Starburst galaxies at low and high redshift
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The Antennae with Spitzer and VISIR
contours:
dust continuum
IRAC/Spitzer
(Wang et al., 2004)
Starburst galaxies at low and high redshift
[NeII] 12.8 mm
ESO/VLT VISIR
(Snijders et al., in prep.)
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Probing dense molecular gas
Line
Tex
[K]
ncrit
[cm—3]
CO 10
5.5
1.7∙103
CO 43
55
8.0∙104
CO 65
116
2.5∙105
HCN 10
4.3
1.4∙105
HCN 43
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5.5∙106
Starburst galaxies at low and high redshift
molecular gas
temperature of dense gas
dense molecular gas
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Dense gas in the ULIRG Mrk231
(Papadopoulos & Van der Werf 2001)
Mrk231 CO 65 and 43
Starburst galaxies at low and high redshift
RxW/JCMT
(Papadopoulos, Isaak & Van der Werf 2006)
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Again: dense gas in Mrk231
Mrk231 CO 32 and 10HCN 43
Starburst galaxies at low and high redshift
RxB3/JCMT
(Papadopoulos, Isaak & Van der Werf 2006)
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Two phases of molecular gas
Combine these data with CO 10, 21 and 13CO 21 (upper limit):
no model reproduces all CO lines:
CO 43/65 and CO 10/21/32 probe different gas phases.
diffuse phase: T 50—85 K and n 300—103 cm—3,
dense phase: T 50—65 K and n 104 cm—3.
Total mass of molecular gas from CO:
M 3.5∙1010 M (or up to a factor 4—5 lower).
Mass of dense molecular gas from HCN:
M 1.5—3.5∙1010 M.
Almost all molecular gas in Mrk231 is dense.
Starburst galaxies at low and high redshift
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ULIRGs and galaxy formation
Locally, ULIRGs are energetically unimportant:
contribute only 2% of local bolometric energy density
How important are ULIRGs at high z?
observe redshifted far-IR emission in submillimetre
with JCMT/SCUBA
Local ULIRGs almost always have a hidden AGN:
causal link with the extreme starburst?
Are high-z ULIRGs the sites of the coeval formation of spheroids and
supermassive black holes?
question for the coming decade
Starburst galaxies at low and high redshift
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Cosmic energy density
1mm
Microwave
Background
1mm
IR/Optical
Background
1nm
(Puget et al. 1996, Hauser et al. 1998
Fixsen et al. 1998)
X-Ray
Background
Stars+BlackHoles
Big Bang
Starburst galaxies at low and high redshift
AGN
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Is obscured star formation important?
Direct
starlight:
nIn = 1.7 . 10-5 erg/s/cm2/sr
Far-IR
background:
nIn = 3.1 . 10-5 erg/s/cm2/sr
Obscured star
formation
dominates.
Starburst galaxies at low and high redshift
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Submillimetre cosmology
Large negative k-correction:
Submm samples have high
proportion of high-z galaxies
Galaxies up to z 10 detectable
Brightness-limited
volume-limited
Luminosities without precise
redshifts
Sources do not fade much from
z=1 to 10
Deeper surveys probe fainter
galaxies, not higher z
Starburst galaxies at low and high redshift
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Counts and backgrounds
Resolved background at 850mm:
25% down to 2 mJy
Connection to other populations
at fainter flux levels.
Lensing can probe these.
Submm background comes
from small number of
(ultra)luminous galaxies
Starburst galaxies at low and high redshift
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SCUBA/JCMT lensed galaxy survey
12 gravitationally lensing clusters
1 blank field (NTT Deep Field)
Survey area 72 arcmin2
Deepest fields are confusionlimited (2 mJy)
55 sources detected at 850 mm
Knudsen PhD thesis
Van der Werf
Starburst galaxies at low and high redshift
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Faint submillimetre source counts
Counts imply strong evolution
First time the faint submm
population is substantially probed
Connection with optical population
Turnover in counts detected for the
first time
(Knudsen, Van der Werf & Kneib, in prep.)
Starburst galaxies at low and high redshift
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Submillimetre source counts
and evolution
luminosity evolution:
L (1+z)p
density evolution:
N (1+z)q
Counts + background imply
pure luminosity evolution
proportional to (1+z)3
Starburst galaxies at low and high redshift
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Submm galaxies in the NTT Deep Field
Not an ERO (?)
ERO
(Knudsen et al. in preparation)
Starburst galaxies at low and high redshift
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FIRES: Faint Infrared Extragalactic Survey
ISAAC/Antu
HDF-S: Labbé et al., 2003
MS1054—03: Förster Schreiber et al., 2006
Starburst galaxies at low and high redshift
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Starburst galaxies at low and high redshift
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FIRES allows better mass selection
I814
Ks
the 6 most massive z 3 galaxies in the HDF-S
FIRES allows selection of high-z galaxies in the rest-frame V-band
much closer to a mass-selection than rest-frame UV
a new class of high-z galaxies: Distant Red Galaxies (DRGs)
Starburst galaxies at low and high redshift
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Rest-frame SEDs: Lyman break galaxies
Starburst galaxies at low and high redshift
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Rest-frame SEDs: distant red galaxies
(Förster Schreiber et al., 2004)
Starburst galaxies at low and high redshift
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Selection of distant red galaxies
(Franx et al., 2003)
Starburst galaxies at low and high redshift
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DRGs are (mostly) star forming galaxies
star formation rates
> 100 M yr—1
(Van Dokkum et al., 2004)
Starburst galaxies at low and high redshift
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SCUBA observations of MS1054–03
M1383
S850 = 5 mJy
Starburst galaxies at low and high redshift
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Submm galaxies and DRGs
Lyman Break Galaxies have no detectable submm emission even after
massive source stacking
Distant Red Galaxies are massive and have high SFRs
DRGs: 3 arcmin–2 for K<22.5
same source density as submm galaxies with >0.8 mJy at 850 mm
1 FIRES field observed with SCUBA: 1 DRG detected directly (5 mJy)
connection between sub-mJy submm galaxies and DRGs?
Starburst galaxies at low and high redshift
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Stacking DRGs
DRGs, EROs
DRGs:
S850 = 1.11 0.28 mJy
(Knudsen et al., 2005)
random positions
Starburst galaxies at low and high redshift
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Breaking the confusion barrier:
gravitational lenses
A2218
Starburst galaxies at low and high redshift
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A2218: SCUBA 850 mm
Starburst galaxies at low and high redshift
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The submm triple behind A2218
Triple image, z=2.515
Magnification in total factor 40
Intrinsic 850 mm flux: 0.8 mJy
Redshifted H:
strong star formation
J–K=2.7: Distant Red Galaxy
(Kneib et al., 2004a)
Starburst galaxies at low and high redshift
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CO 3–2 detection of the submm triple
(Sheth et al., 2004;
Kneib et al., 2005b)
Detected both at Owens Valley and Plateau de Bure
CO line width less massive than bright SMGs but comparable to DRGs
Starburst galaxies at low and high redshift
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Conclusions and outlook: low z
Gas density is crucial in
determining starburst
properties; also related to
depth of potential well?
Luminous starbursts tend to
have both high L/M and high M
Molecular lines probe
density/temperature structure
The future: SINFONI+LGS,
APEX, HIFI/Herschel, ALMA
Starburst galaxies at low and high redshift
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Conclusions and outlook: high z
Starbursts are a key process in galaxy evolution
We are looking back towards a strongly obscured universe,
energetically dominated by dusty starbursts
DRGs are massive and have high SFRs; as a population they are at
least as important as LBGs for cosmic mass budget and SFR
Connection between DRGs and faint submm galaxies
The future: SCUBA2, ALMA, HAWK-I, JWST, ELT
Starburst galaxies at low and high redshift
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To coldly go…: SCUBA-2
SCUBA-2 will bring rectangular array
imaging to submm astronomy
8 4032 sub-arrays – 4 at 850 mm,
4 at 450 mm
Mapping speed unequalled
Operational mid-2007
Legacy programs defined:
Cosmological survey
Full Galactic plane survey
Full Gould’s Belt survey
Shallow “all-sky” survey
Unbiased debris disk survey
Starburst galaxies at low and high redshift
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SCUBA-2 Cosmology Legacy Survey
1 deg2 field, will be mapped to confusion limit in 23
hours by SCUBA-2 at 850 mm
4 PIs: Dunlop, Halpern, Smail,
Van der Werf
Large survey (20 deg2) at 850 mm,
deep survey at 450 mm (0.5 deg2)
450 mm survey will resolve full
submm background and detect all
LIRGs in the survey area out to z=2
(ULIRGs out to z=4)
Connection with other populations:
optical, near-IR, X-ray, radio,…
SCUBA-2 field-of-view
Starburst galaxies at low and high redshift
Time allocation 102 good nights
(including 50% of the best weather
until mid-2009)
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« We are, by definition, in the very center of the observable region.
We know our immediate neighborhood rather intimately. With
increasing distance, our knowledge fades, and fades rapidly.
Eventually, we reach the dim boundary, the utmost limits of our
Telescopes. There, we measure shadows, and we search among
ghostly errors of measurement for landmarks that are scarcely
more substantial.
The search will continue. Not until the empirical resources are
exhausted, need we pass on the dreamy realms of speculation. »
Edwin Hubble, The Realm of the Nebulae (1936)
Starburst galaxies at low and high redshift
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