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David Elbaz Tracing back the history of galaxies Page 1
Tracing back the history of galaxies from fossil records (metals, cosmic background,...) and direct measurements (deep surveys, galaxy counts,
luminosity funct., cosmic SFR history)
• Fossil record:– stellar diagnostics– metals– cosmic background
• "direct" measurement of "past" activity / deep extragalactic surveys:– number counts = resolving the background in
projection– luminosity functions = resolving the background in time– cosmic SFR history = integrating the luminosity function / z bin
• Are the 2 methods consistent ?…– cosmic stellar mass building history = integrating the cosmic SFR
history– cosmic density of metals = global energy budget of
nucleosynthesis– cosmic density of supermassive black holes= energy budget of
accretion
David Elbaz Tracing back the history of galaxies Page 2
Deriving a SFR from a luminosity…
SFR = C x L(UV) , where C is in M yr-1 L-1
David Elbaz Tracing back the history of galaxies Page 3
SFR vs age, metallicity and extinction…
Worthey (1994, ApJS 95, 107)
David Elbaz Tracing back the history of galaxies Page 4
SFR vs age, metallicity and extinction…
Devriendt et al. 99
Visible Infrared mmUV
wavelength
inte
nsit
é
dust
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SNII = core collapse SN
progenitors : >8-10M , lifetime= 3-20 Myr
SNIa = thermonuclear explosion of accreting
C-O white dwarfs when WD mass Chandra.
limit (>1.4 M => > e- degeneracy pressure)
progenitors : 3-8M , lifetime= 20-450 Myr
Thomas et al. 05
SNIa:O-> Si28-> Ni56-> Co56-> Fe56
Braking the age - metallicity degeneracy using supernovae
David Elbaz Tracing back the history of galaxies Page 6
Braking the age - metallicity degeneracy using supernovae
Ferreras & Silk 02
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4000 Å break and Balmer absorption lines
H
CaIIH&K
H8
H9
H10
OII
H
H
H
OIII
OIII
Elliptical early-type Spiral (Sa)(with proeminent bulge)
late-type Spiral (Sc)(with open arms)
Irregular
David Elbaz Tracing back the history of galaxies Page 8
D4000 from accumulation of metallic lines and Balmer absorption lines: break more important with decreasing surface temperature of star (less ionization, more opacity), i.e with increasing age.
EW(H)
4000 Å break and Balmer absorption lines
Gyr
EW(H)
SDSS data
Kauffmann et al 03
Marcillac, Elbaz et al (2006, A&A 458, 369)
David Elbaz Tracing back the history of galaxies Page 9
SDSS : 104 °2, North Hem. ugriz, 106
spectra r < 17.77(Sloan Digital Sky Survey)
RedRed
BlueBlue
(Kauffmann et al. 2003)
4x104x1010 10 MM
Galaxy bimodality: a clear and mysterious dichotomy between 2 galaxy groups, red-old-dead vs blue-active
David Elbaz Latest news from deep infrared surveys 10
CGRB
Blazars
300m 3m 300nm 0.4keV 40keV 4MeV 400MeV
Hasinger ‘00
15m (Elbaz et al. 02)
David Elbaz Latest news from deep infrared surveys 11
CGRB
Blazars
300m 3m 300nm 0.4keV 40keV 4MeV 400MeV
Hasinger ‘00
obscured AGNs
Compton thin
unobscured AGNs
Compton Thick AGNs
Gilli et al.
David Elbaz Tracing back the history of galaxies Page 12
Energetic budget
Nucleosynthesis get its energy from:
p -> He -> C, N, O, Fe…mp= 0.93828 GeVmn= 0.93857 GeV
Binding energy from H to He: 7 MeV
p -> He: radiates 7MeV per unit 0.93828
GeV -> 0.74 % of mass converted in
lightfor He, then an extra 0.1% for C, N, O, Fe. In practice, ~60%
of the metals are in the form of Oxygen (8 MeV), about 7 % in Fe (8.6 MeV), and the rest in C,
N mostly (7.5 MeV)
Globally the budget of nucleosynthesis is such that :Energy radiated = 0.0084 x mass of metals x c2 [ Joules ]
per unit time, when dM metals are produced in dt :Luminosity radiated = d [ 0.0084 MZc2 ] / dt
Hence globally, 0.84 % of the mass in the form of metals today was radiated (E=Mc2) over the history of the Universe.
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Energetic budgetWhen dM metals are produced in dt, the luminosity radiated is:
L = d [ 0.0084 MZc2 ] / dt = 0.0084c2 dMZ/dt [W]Per unit volume:L= 0.0084c2 dZ/dt [Wm-3]
Over the history of the Universe, metals have been produced through nucleosynthesis in all stars, leading to an average metal content per unit volume, Z(z~0).The energy density generated by stars over the history of the Universe is:
L=∫Ldt = 0.0084 Z c2 [ J m-3]
On earth, we measure fluxes per unit solid angle in: W m-2 sr-1.The cosmic background, or extragalactic background light (IGL) is measured in those units, it measures :the number of photons which have an energy hobserved [ J ] that we collect per unit telescope area [m-2] and per unit time [s-1] over a given solid angle [sr-1].Photons arrive to us at a speed of "c" [ms-1], hence when we integrate during "dt", we get all the light contained in a tube of "c dt" length.Hence, when we observe "d/4" of the sky during "dt", we get:
Lx cdt x d/4or per unit time : Lx c / 4
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Energetic budget
So :L=∫Ldt = 0.0084 Z c2 [ J m-3]
And when we observe "d/4" of the sky during "dt", we get: Lx cdt x d/4or per unit time : Lx c / 4[W m-2 sr-
1]
But we measure hobserved [ J ] and what was produced is: hemitted hobserved = hemitted / (1+zemitted)
So finally, the measured background is:IGL = Lx c / 4/ (1+zem) = 0.0084 Z c3 / [4x (1+zem)] [W m-2 sr-1]
Where: Z is the local metal density
zem is the redshift at which these metals were produced
To know the total amount of light ever produced by stars, we need to determine these two numbers.
David Elbaz Tracing back the history of galaxies Page 15
Computation of the local metal density
Baryons in the form of stars (+ stellar remnants) make locally:
Ωbulges = bulges/c ~ 0.002600 h-1 (Fukugita, Hogan, Peebles
1998)
Ωdisks = disks/c ~ 0.000860 h-1
Ωirregulars = irregulars/c ~ 0.000069 h-1
where: =/c with ρc = 9.47 x 10-27 kg m-3= 3H02/(8G)
(H0=71 km s-1Mpc-1 ; G=6.67x10-11 m3 kg-1 s-2 ; h=H0/100=0.71)
bulges ~ 3.5 x 10-29 kg m-3, Zbulges ~2 x Z= 0.04 => bulgesmetals~ 14.0 x
10-31 kg m-3
disks ~ 1.1 x 10-29 kg m-3, Zdisks~1 x Z= 0.02 => diskmetals ~ 2.3 x
10-31 kg m-3
irregulars~ 0.09 x 10-29 kg m-3, Zirregulars ~ 0.02 => irregulmetals ~ 0.2 x
10-31 kg m-3
=> * galaxiesmetals ~ 1.8 x 10-30 kg m-3
Intergalactic medium:
In galaxy clusters= intra-cluster medium: ΩICM=ICM/c~0.0026 h-1
Where: ZICM=0.3 x Z= 0.006 => ICMmetals ~ 2.1 x 10-31 kg m-3
In galaxy groups= intra-group medium: Ωgroups= groups/c ~ 0.0056 h-1
Where: ZICM=0.3 x Z= 0.006 => groupsmetals ~ 4.5 x 10-31 kg m-3
=> IGMmetals ~ 0.7 x 10-30 kg m-3
=> TOTAL: Z ~ 2.5 x 10-30 kg
m-3
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The local cosmic metal density
• From previous considerations, we get:Z = 25 x 10-31 kg m-3
• Calura & Matteucci (2004, MNRAS 350, 351) : Z= 9.37 x 106 M Mpc-3
= 9.37 x 106 x 1.989 x 1030 / (3.0856 x 1022)3 kg m-3
Z = 6.34 x 10-31 kg m-3
• Mushotzky & Lowenstein (1997) : Z= 1.4 x 107 M Mpc-3 = 9.5 x 10-31 kg m-3
• Zepf & Silk (1996) : Z= 4 x 107 M Mpc-3 = 27 x 10-31 kg m-3
• Madau et al. (1996) : Z= 5.4 x 106 M Mpc-3 = 3.7 x 10-31 kg m-3
• So globally, we get : Z = [4 - 27] x 10-31 kg m-3
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The integrated galaxy light from nucleosynthesis
• So globally, we get : Z = [4 - 27] x 10-31 kg m-3
IGL = 0.0084 Z c2 / [4x (1+zem)] [W m-2 sr-1]
= ( Z /10-31 kg m-3) x 1.8 / (1+zem) [nW m-2 sr-1]
IGL = [7 - 49] / (1+zem) [nW m-2 sr-1]
The stellar mass density per unit comoving volume is ~half the present-day one around z~1, so we can assume and average: zem
~ 1
IGL = 3.5 - 25 [nW m-2 sr-1]
With our estimate, we get: IGL = 25 [nW m-2 sr-1]
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The integrated galaxy light from nucleosynthesis
• So globally, we get : IGL = 25 [nW m-2 sr-1] possibly ( 3 - 25 )
Dole et al (2006)
~24 nWm-2sr-1~23 nWm-2sr-1
This is the good order of magnitude !A factor 2 below: missing metals ? (extragalactic stars ? IGM ?) Other source of energy ?
David Elbaz Tracing back the history of galaxies Page 19
Marconi & Hunt Tremaine et al.
MBH~2x10-3 x M*bulge
Gebhardt et al. (2000), Ferrarese & Merritt (2000) c.f. Magorrian (1998)
MBH = 1.5x108 2004 M
where 200=/200 km s-1
Every galaxy contains a central supermassive black hole
David Elbaz Tracing back the history of galaxies Page 20
Contribution of "Black Holes" to the cosmic background light
MBH ~ 2x10-3 x M*(bulges) & bulges ~ 3.5 x 10-29 kg m-3 BH ~ 7
x 10-32 kg m-3
During the gravitational accretion through which supermassive black hole
grow,
the gravitational potential energy is converted into light with a given
efficiency .
Instead of "0.0084 x m" for nucleosynthesis, we have here: " x BH".
Typical value generally assumed : ~5-10 %
IGLSMBH = x BH c3 / (4x (1+z)) = [7.5 - 15] /(1+z) nW
m-2 sr-1
For z~1, we get : IGLSMBH ~ 4 - 8 nW m-2 sr-1
To be compared to: IGLnucleosynthesis ~ 25 nW m-2 sr-1
On average nucleosynthesis produces 3-5 times more energy than
accretion.
The observed cosmic background is : EBL ~ 47 nW m-2 sr-1
David Elbaz Tracing back the history of galaxies Page 21
Application to the Milky Way
The total energy radiated by stars in the MW has been : 0.0084 x (ZM*) c2
Where : Z=0.02 et M*~ 7x1010M
This energy was radiated over its lifetime : T = 12 Gyr
If the rate of star formation had been constant, we would expect a luminosity of :
L = 0.0084 x (ZM*) c2 / T => L~1.3x1010 L
Observation:
LV(disk)=1.2x1010 L, LB(bulge)=0.25x1010 L => L~1.45x1010 L (Binney &
Tremaine)
L(MW)=[3.8±0.6]x1010 L (Flynn et al 06)
The present SFR of the MW is : SFR(V.L.)=3.8 ± 2.2 M
(Diehl et al. 2006, Nature 439, 45, radioactive decay of Al26 in photons in
supernovae), agrees with OB associations (McKee & Williams 1997, ApJ 476, 144):
If it had been the same over 12 Gyr: M* < SFR x 12Gyr = 4.6x1010 M
=> the SFR the MW was at least ~1.7 times larger in the past to explain its present
stellar mass.
Logical since we observe : SFR~gaz1.4 (Schmidt-Kennicutt law)
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Galaxy countsThe cosmic background collects the mixed contribution of all galaxies projected on the sky= extragalactic background light (EBL)
Deep surveys can spatially resolve the background into individual galaxies contributions= integrated galaxy light (IGL)
Differential counts: number of galaxies per flux density interval, i.e. dN/dS.Integral counts: number of galaxies brighter than a given flux density limit, i.e. N(≥S).where:
- N= number of galaxies / square armin (steradians)- S = flux density in W m-2 sr-1 (or in apparent magnitude)
EBL IGL
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A reference case : Euclidean countsBasic assumptions:- number of galaxies/unit volume at given luminosity L is: (L)= dN/dL(L) x dL (# Mpc-3)
(L) = luminosity function- sources are homogeneously distributed in euclidean Universe (no expansion)
An image of the sky (survey) with a given depth "Slim" only detects objects closer than :
dlim = (L/4Slim)1/2
Over the whole sky, the total number of galaxies of luminosity "L" visible in the survey is
N(≥S,L)dL = (L) (4/3) dlim3 = (L) (4/3) dlim
3 Over the solid angle of the survey, one gets :
N(≥S,L)dL = (L) (/3) dlim3 = (L) (/3) (L/4Slim)3/2
The total number of sources detected in the survey, including all luminosities is:
Hence the euclidean integral counts: N(≥S) ~ S-3/2
The power "3" comes from the increasing volume with distance -> larger # of galaxies
The power "-1/2" comes from the dilution of flux with increasing distanceThe differantial euclidean counts= derivative of N(>S): dN/dS ~ S-5/2
With apparent magnitudes, one gets : N(≤m) ~ 100.6m
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Differential counts at 15 m from ISOCAM
Elbaz (2005)
Euclidean no k-correction
Euclidean with k-correction
David Elbaz Latest news from deep infrared surveys 25
Differential counts in Spitzer passbands
15 m 24 m 70 m
160m 850m
Le Borgne, Elbaz, Ocvirck, Pichon 2008
David Elbaz Latest news from deep infrared surveys 26
Differential counts in Spitzer passbands
15 m 24 m 70 m
160m 850m
David Elbaz Latest news from deep infrared surveys 27
Differential counts in Spitzer passbands
15 m 24 m 70 m
160m 850m
David Elbaz Latest news from deep infrared surveys 28
Origin and interpretation of galaxy number counts
GOODS-N24m
Spitzer
David Elbaz Latest news from deep infrared surveys 29
The average sources responsible for the cosmic bkg
• In the far IR: z~0.8 , LIR~3x1011 L , SFR ~ 50 M yr-1
• In optical-near IR: z~0.5, mAB~19 , L(0.5 m)~7x1010 L
Pozzetti & Madau 01
50% from z~0.5
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Luminosity function
In comoving volume: necessary to test the evolution of the number density of galaxies (e.g. merging rate)
Luminosity function = number of galaxies/unit volume at given luminosity(L)= dN/dL(L) x dL (# Mpc-3)
An image of the sky (survey) with a given depth "Slim" only detects objects closer than :
dlim = (L/4Slim)1/2
Hence in a limited volume which depends on luminosity:each luminosity bin must therefore be weighted by its associated "maximum volume"= V/Vmax technique
The luminosity density is = where
Volume = comoving volume 4/3 [ Dm3(z+dz/2) - Dm
3(z-dz/2) ]
where Dm is the radial comoving distance.
max
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Angular diameter distance, DA, and radial comoving distance, Dm
• DA: connects the apparent size of a galaxy, arcseconds, to its physical size, dkpc. dkpc=DA
• DM : follows the Universe expansion : Dm=(1+z)DA
c dt = distance travelled by light x1/R(t) = during dt the Universe expanded (R(t)= scale factor= 1/(1+z) )• DL: luminosity distance DL=(1+z)Dm=(1+z)2DA , when z is small, DL ≈Dm ≈ DA ≈ cz/H0
scale factor: R(t)=1/(1+ z) => z=1/R - 1 => dz/dt = - dR/dt /R2
And the Hubble "constant" is: H= dR/dt / R , hence: dz/dt = - H(z) / R or dt/R= - dz /H(z)Friedmann equation:
comoving volume per square arcmin (or V/4sr-1) and redshift bin (dz)
2
David Elbaz Tracing back the history of galaxies Page 32
Comoving volume (Mpc3) / arcmin2
2
comoving volume per square arcmin (or V/4sr-1) and redshift bin (dz)
David Elbaz Tracing back the history of galaxies Page 33
Luminosity function
Analystical Schechter LF (1976, ApJ 203, 297; 13 galaxy clusters) for local Universe :
~(L/L*)
~exp-(L/L*)
(L)
(L)xL/L*
David Elbaz Tracing back the history of galaxies Page 34
Total luminosity density
≈[-0.9,-1.16] => +2)≈0.84)≈1=> Ltot≈ *L* where 0.0153h3Mpc-3 h=H0/100 ≈ 0.7 => 0.00525 Mpc-3
1 galaxy/190Mpc3, i.e. /6 Mpc on a side and L*≈ 1.4 x 1010 L(~MW) so :
Ltot = L* ≈ 7.3x107 LMpc-3
≈ *L*
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Bolometric luminosity function
LIR=L(8-1000m)"luminous IR galaxies" (LIRGs) : 11≤log(LIR/L)<12 "ultra-luminous IR galaxies" (ULIRGs) : 12≤log(LIR/L)<13 "hyper-luminous IR galaxies" (HyLIRGs) : 13≤log(LIR/L)
Sanders & Mirabel (1996, ARAA 34, 749)
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The cosmic SFR history derived from the UV light
Madau et al (1996)Lilly et al (1996)
Madau et al (1996)
Metal production
Star production
David Elbaz Latest news from deep infrared surveys 37
Cosmic history of star formation
13% of local * density13% of local * density50%50% 23%23%
43%43% 24%24% 16% of Universe age16% of Universe age
>20M>20Myryr-1-1>200M>200Myryr-1-1
David Elbaz Latest news from deep infrared surveys 38
Cosmic history of star formation
Density of AGNs (Wall et al 05)Density of AGNs (Wall et al 05)
13% of local * density13% of local * density50%50% 23%23%
43%43% 24%24% 16% of Universe age16% of Universe age
David Elbaz Tracing back the history of galaxies Page 39
Tracing back the history of galaxies from fossil records (metals, cosmic background,...) and direct measurements (deep surveys, galaxy counts,
luminosity funct., cosmic SFR history)
• Fossil record:– stellar diagnostics– metals– cosmic background
• "direct" measurement of "past" activity / deep extragalactic surveys:– number counts = resolving the background in
projection– luminosity functions = resolving the background in time– cosmic SFR history = integrating the luminosity function / z bin
• Are the 2 methods consistent ?…– cosmic stellar mass building history = integrating the cosmic SFR
history– cosmic density of metals = global energy budget of
nucleosynthesis– cosmic density of supermassive black holes= energy budget of
accretion
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