David ElbazTracing back the history of galaxies Page 1 Tracing back the history of galaxies from...

David Elbaz Tracing back the history of galaxies

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


Deriving a SFR from a luminosity…

SFR = C x L(UV) , where C is in M yr-1 L-1


SFR vs age, metallicity and extinction…

Worthey (1994, ApJS 95, 107)


SFR vs age, metallicity and extinction…

Devriendt et al. 99

Visible Infrared mmUV

wavelength

inte

nsit

é

dust


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


Braking the age - metallicity degeneracy using supernovae

Ferreras & Silk 02


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


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)


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)


CGRB

Blazars

300m 3m 300nm 0.4keV 40keV 4MeV 400MeV

Hasinger ‘00

obscured AGNs

Compton thin

unobscured AGNs

Compton Thick AGNs

Gilli et al.


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.


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


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.


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


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


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]


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 ?


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


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


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)


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


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


Differential counts at 15 m from ISOCAM

Elbaz (2005)

Euclidean no k-correction

Euclidean with k-correction


Differential counts in Spitzer passbands

15 m 24 m 70 m

160m 850m

Le Borgne, Elbaz, Ocvirck, Pichon 2008



15 m 24 m 70 m

160m 850m


Origin and interpretation of galaxy number counts

GOODS-N24m

Spitzer


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


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


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


Comoving volume (Mpc3) / arcmin2

2

comoving volume per square arcmin (or V/4sr-1) and redshift bin (dz)


Luminosity function

Analystical Schechter LF (1976, ApJ 203, 297; 13 galaxy clusters) for local Universe :

~(L/L*)

~exp-(L/L*)

(L)

(L)xL/L*


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*


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)


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


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


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


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 ElbazTracing back the history of galaxies Page 1 Tracing back the history of galaxies from...

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