The early Universe just around the corner: Fornax · PDF fileThe early Universe just around the corner: Fornax dSph ... A unique oportunity ... (km s 1) 55.3 0.1 Luminosity, L V (L

The early Universe just around thecorner: Fornax dSph

Andres del Pino MolinaUniversidad de La Laguna; Instituto de Astrofısica de Canarias, 2012

Outline

1 Introduction

2 The data

3 Obtaining the SFH and the spatial distribution

4 Results

5 Discussion and Conclusion

2/34

Outline

1 Introduction

2 The data


4 Results


Introduction 3/34

A dark matter UniverseVery brief description

Nowadays the most accepted scenario.

ΛCDM

Small systems =⇒ Big structures.

Dwarf galaxies survivors.

But there are some issues.

The missing satellites problem

Few found dwarf galaxies.

Models predict much more halos.

Introduction 4/34

A dark matter UniverseVery brief description

Nowadays the most accepted scenario.

ΛCDM

Small systems =⇒ Big structures.

Dwarf galaxies survivors.

But there are some issues.

The missing satellites problem

Few found dwarf galaxies.

Models predict much more halos.

Introduction 4/34

A dark matter UniverseQuenching the star formation: Dark halos

Three main processes proposed as inhibitors of SF:

Heating from the UV radiation arising from cosmicreionization (Barkana & Loeb 2001).

Effects from UV

{SF suppression. M . 109M�keep forming stars. M & 109M�

SNe feedback mass ejection (Mac Low & Ferrara 1999).

Effects from SNe

{Gas completely blown away. Mb . 107M�Galaxy conserve gas. Mb & 108M�

Tidal stirring ( Lokas et al. 2011, Mayer et al. 2006, 2008).

Observed galaxies below these limits

These galaxies must be dark!

Introduction 5/34

A dark matter UniverseQuenching the star formation: Dark halos

Three main processes proposed as inhibitors of SF:

Heating from the UV radiation arising from cosmicreionization (Barkana & Loeb 2001).

Effects from UV

{SF suppression. M . 109M�keep forming stars. M & 109M�

SNe feedback mass ejection (Mac Low & Ferrara 1999).

Effects from SNe

{Gas completely blown away. Mb . 107M�Galaxy conserve gas. Mb & 108M�

Tidal stirring ( Lokas et al. 2011, Mayer et al. 2006, 2008).

Observed galaxies below these limits

These galaxies must be dark!

Introduction 5/34

A dark matter UniverseQuenching too much.

Several theories have been proposed to overcome this apparentcontradiction:

Bullock et al. (2001): Halos formed during theprereionization era. 90% below observable limits.

Stoehr et al. (2002): Masses of dark matter halos larger thanthose measured at the optical limit.

Kravtsov et al. (2004): Larger halos in the pass.

Susa & Umemura (2004): Self-Shielding effect.

Busha et al. (2010): Inhomogeneous reionization.

Introduction 6/34

Local Group GalaxiesA unique oportunity

Their proximity allow us to resolve their stars individually.

Dwarf Spheroidal Galaxies (dSph)

The most common.

Low surface luminosity (∑

v . 0.002L�pc−2).

Small sizes (a few hundred of parsecs).

Lack of gas.

Relatively large velocity dispersion (>7 km s−1)

Abundant presence of dark matter.M/L ∼ 5− 500 In solar units (virialized).

Introduction 7/34

Local Group GalaxiesA unique oportunity

Their proximity allow us to resolve their stars individually.

Dwarf Spheroidal Galaxies (dSph)

The most common.

Low surface luminosity (∑

v . 0.002L�pc−2).

Small sizes (a few hundred of parsecs).

Lack of gas.

Relatively large velocity dispersion (>7 km s−1)

Abundant presence of dark matter.M/L ∼ 5− 500 In solar units (virialized).

Introduction 7/34

Local Group GalaxiesThe Milky Way satellites

Figure: The Milky Way classic satellites

Introduction 8/34

Fornax dSphOur particular object

Introduction 9/34

Fornax dSphSome data

A quick look

Complex system.

The largest and most luminous of the dSphscompanion of the MW.

It host globular clusters.

Shows two shell structures.

Introduction 10/34


Fornax at glance

RA, α (J2000.0) 2h 39’ 53.1”Dec, δ (J2000.0) -34o 30’ 16.0”Galactic longitude, l (deg) 237.245Galactic latitude, b (deg) -65.663Heliocentric distance (kpc) 138±8Heliocentric radial velocity (km s−1) 55.3±0.1Luminosity, LV (L�) 15.5× 106

Ellipticity, e 0.30± 0.01Position angle (deg) 41±6Core radius (pc) ∼460 (13.8±0.8 arcmin)Tidal radius (kpc) ∼2.4 (71±4 arcmin)

Table: Fornax main data.

Introduction 11/34


Fornax at glance

RA, α (J2000.0) 2h 39’ 53.1”Dec, δ (J2000.0) -34o 30’ 16.0”Galactic longitude, l (deg) 237.245Galactic latitude, b (deg) -65.663Heliocentric distance (kpc) 138±8Heliocentric radial velocity (km s−1) 55.3±0.1Luminosity, LV (L�) 15.5× 106

Ellipticity, e 0.30± 0.01Position angle (deg) 41±6Core radius (pc) ∼460 (13.8±0.8 arcmin)Tidal radius (kpc) ∼2.4 (71±4 arcmin)

Table: Fornax main data.

Introduction 11/34

Outline

1 Introduction

2 The data


4 Results


The data 12/34

Data setsThree kind of observations

−34◦ 50′

−34◦ 40′

−34◦ 30′

−34◦ 20′

δ 2000

2h 39m2h 40m2h 41m

α2000

2

4Hip 12393

3

E

N

Wide field photometry (Stetson2000, 2005)

mI . 23

∼ 0.7 degrees2 covered

Deep FORS1@VLT photometry

mI . 25

∼ 135 arcmin2 covered

Spectroscopy (Battaglia et al.2006)

CaT metallicities of RGB stars

The data 13/34


−34◦ 50′

−34◦ 40′

−34◦ 30′

−34◦ 20′

δ 2000

2h 39m2h 40m2h 41m

α2000

Hip 12393

3

4

2E

N


mI . 23



mI . 25




The data 13/34


−34◦ 50′

−34◦ 40′

−34◦ 30′

−34◦ 20′

δ 2000

2h 39m2h 40m2h 41m

α2000

2

4Hip 12393

3

E

N


mI . 23



mI . 25




The data 13/34

Outline

1 Introduction

2 The data


4 Results


Obtaining the SFH and the spatial distribution 14/34

Wide field photometryObtaining the spatial distribution maps

Five regions in the CMD

HB: Old (& 11− 12Gyrs).

RGB: Intermediate-old(& 1− 2Gyrs).

RC: Intermediate-young.

BP: Young (& 1Gyr ,. 4Gyrs).

BBP: Very young(. 1− 2Gyrs).

Spatial distribution maps

2d histogram of 142 x 128 pixels.

Normalized & convolved with a gaussian filter.


Wide field photometryObtaining the spatial distribution maps

Five regions in the CMD

HB: Old (& 11− 12Gyrs).

RGB: Intermediate-old(& 1− 2Gyrs).

RC: Intermediate-young.

BP: Young (& 1Gyr ,. 4Gyrs).

BBP: Very young(. 1− 2Gyrs).

Spatial distribution maps

2d histogram of 142 x 128 pixels.

Normalized & convolved with a gaussian filter.


Deep photometryThe stars position

Deep photometric list selection

We define three regions:

Name of Region Surface (pc2) Galactocentric dist. (pc) No. of stars

Inside the Core 1 (IC1) 75770.1 56.8 69590Inside the Core 2 (IC2) 84248.6 360.4 69712Outside the Core (OC) 59181.5 473.6 38643

−34◦ 50′

−34◦ 40′

−34◦ 30′

−34◦ 20′

δ 2000

2h 39m2h 40m2h 41m

α2000

Hip 12393

3

4

2E

N


Deep photometryThe stars position

Deep photometric list selection

We define three regions:

Name of Region Surface (pc2) Galactocentric dist. (pc) No. of stars

Inside the Core 1 (IC1) 75770.1 56.8 69590Inside the Core 2 (IC2) 84248.6 360.4 69712Outside the Core (OC) 59181.5 473.6 38643

−34◦ 50′

−34◦ 40′

−34◦ 30′

−34◦ 20′

δ 2000

2h 39m2h 40m2h 41m

α2000

OC

3

4

2

Hip 12393IC1

IC2

E

N


Deep photometryObserved CMDs

Isochrones from BaSTI stellar evolution library: Z=0.004, 1Gyr(dotted-dashed green) and Z=0.001, 13.5 Gyr (red solid line).


Deep photometryObserved CMDs

Isochrones from BaSTI stellar evolution library: Z=0.004, 1Gyr(dotted-dashed green) and Z=0.001, 13.5 Gyr (red solid line).


Deep photometryObtaining the SFH

Synthetyc CMDs fitting techniques (Aparicio & Hidalgo 2009; Hidalgo etal. 2011).

Basic functions.

SFH defined as ψ(t, z), ψ(t, z)dtdz is the mass transformed in starsin t ′ (t < t ′ < t + dt) with z ′ (z < z ′ < z + dz).

IMF, Frequency and distribution of binary stars masses β(f , q), etc.

sCMD

We created a sCMD populated by millions of stars.

Stars distributed in n ×m simple populations.



Synthetyc CMDs fitting techniques (Aparicio & Hidalgo 2009; Hidalgo etal. 2011).

Basic functions.

SFH defined as ψ(t, z), ψ(t, z)dtdz is the mass transformed in starsin t ′ (t < t ′ < t + dt) with z ′ (z < z ′ < z + dz).

IMF, Frequency and distribution of binary stars masses β(f , q), etc.

sCMD

We created a sCMD populated by millions of stars.

Stars distributed in n ×m simple populations.



Simulating observational effects in the sCMD

Information provided by the completeness test.

S/N limitations.

Detector defects.

Stellar crowding.

etc.



Simulating observational effects in the sCMD

Information provided by the completeness test.

S/N limitations.

Detector defects.

Stellar crowding.

etc.



Sample and comparison of both CMDs

Observed CMD (ψ(t, z)) vs. synthetic CMD (∑n×m

i ψi ).

Process ends with the best solution found: ψ(t, z) = A∑

i αiψi .

We used χ2γ defined by Mighell (1999) as merit function.

Used codes

Four main codes are the mainstays of this method:

IAC-star (Aparicio & Gallart 2004).Obsersin (Hidalgo et al. 2011).IAC-pop (Aparicio & Hidalgo 2009).MinnIAC (Hidalgo et al. 2011).


CaT spectroscopyObtaining the AMR and the metallicity map.

−35◦ 30′

−35◦ 00′

−34◦ 30′

−34◦ 00′

−33◦ 30′

δ 2000

2h 36m2h 40m2h 44m

α2000

4

3

2

15

E

N

Metallicity and age Maps

2d histograms of 30 x 33pixels.

Obtaining the AMR

Stars lying inside the core.

Combining metallicities fromCaT with positions in CMD.

Polynomial relationship(Carrera et al. 2008).


CaT spectroscopyObtaining the AMR and the metallicity map.

−35◦ 30′

−35◦ 00′

−34◦ 30′

−34◦ 00′

−33◦ 30′

δ 2000

2h 36m2h 40m2h 44m

α2000

4

31

5

2

E

N

Metallicity and age Maps

2d histograms of 30 x 33pixels.

Obtaining the AMR

Stars lying inside the core.

Combining metallicities fromCaT with positions in CMD.

Polynomial relationship(Carrera et al. 2008).


Outline

1 Introduction

2 The data


4 Results


Results 22/34

Spatial distributionStrong differences between populations

−15

0

15

∆δ 2

000

[′ ]

Hip

3

2

4

HB

E

N

3

Hip4

2

RGB

E

N

Hip4

3

2

RC

E

N

−15

0

15

∆δ 2

000

[′ ]

−15015

∆α2000 [′]

2

4Hip

3BP

E

N

−15015

∆α2000 [′]

3

2

Hip4

BBP

E

N

−15015

∆α2000 [′]

Hip4

3

2

Total

E

N

Strong asymetries found in the young populations.

Shell like structures of young stars (∼ 2− 3Gyrs).

Results 23/34

The star formation historyGeneral view

Summary

Spread old population.

Narrower metallicityrange in the outskirts.

Results 24/34

The star formation historyGeneral view

Summary

Spread old population.

Narrower metallicityrange in the outskirts.

Results 24/34

The star formation historyDetailed view

0

2

4ψ

(10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1

Look−back time (Gyr)

Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Differences between regions

Last burst located in thecore.

Small differences in theAMR.

SF ends before as we moveoutwards.

Results 25/34

The star formation historyDetailed view

0

2

4ψ

(10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Differences between regions

Last burst located in thecore.

Small differences in theAMR.

SF ends before as we moveoutwards.

Results 25/34

The star formation historyGlobal and cosmological evolution

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Reionization and SNe effects

∼ 90% stars formed afterUV.

Has retained gas againstSNe feedback.

Results 26/34

The star formation historyGlobal and cosmological evolution

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Reionization and SNe effects

∼ 90% stars formed afterUV.

Has retained gas againstSNe feedback.

Results 26/34

The star formation historyPossible tidal interactions

0

2

4ψ

(10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Tidal interaction with the MW?

118 kpc of perigalacticon.

152 kpc apogalacticon.

3.2 Gyr of orbital period.

(Piatek et al. 2007)

Results 27/34

CaT spectroscopyMetallicity and Age map

Metallicity map:

−35◦ 30′

−35◦ 00′

−34◦ 30′

−34◦ 00′

−33◦ 30′

δ 2000

2h 36m2h 39m2h 42m2h 45m

α2000

4

31

5

2

E

N

−2.50

−2.25

−2.00

−1.75

−1.50

−1.25

−1.00

−0.75

−0.50

[Fe/H

]

Age map:

−35◦ 30′

−35◦ 00′

−34◦ 30′

−34◦ 00′

−33◦ 30′

δ 2000

2h 36m2h 39m2h 42m2h 45m

α2000

2

4

15

3

E

N

1.5

3.0

4.5

6.0

7.5

9.0

10.5

12.0

Age

Metallicity and age distributions do not follow opticalshape.

Results 28/34

CaT spectroscopyThe AMR

024681012

−1.5

−1

−0.5


[M/H

]redshift

1

3

5

8

Z ×

10

−3

0.5124611

Results 29/34

CaT spectroscopyComparison between results

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC1

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

358 Z

× 1

0−

3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

IC2

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

0

2

4

ψ (

10

−9 M

yr−

1 p

c−2)

⊙

redshift

OC

−1.5

−1

−0.5

[M/H

]

0246810120

0.5

1


Ψ(t

)

1

3

58

Z ×

10

−3

0.5124611

Fit perfectly!

We can use photometryinstead of spectroscopy.

Results 30/34

Outline

1 Introduction

2 The data


4 Results


Discussion and Conclusion 31/34

Global and local considerations

Reionization and SNe effects on Fornax

� ∼ 90% stars formed after UV.

� Has retained gas against SNe feedback.

}M & 108 − 109M�

(Self-Shielding effect)

Possible tidal interactions

� Our results favored an interaction with a smaller system (∼ 3 Gyrs ago)� Strong asymetries found in the young populations.� Shell like structures of young stars (∼ 2− 3Gyrs).� Z = 0.004 for Clump stars (Olszewski et al. 2006).� Random motion kinematic (Walker & Mateo, 2006).


Global and local considerations

Reionization and SNe effects on Fornax

� ∼ 90% stars formed after UV.

� Has retained gas against SNe feedback.

}M & 108 − 109M�

(Self-Shielding effect)

Possible tidal interactions

� Our results favored an interaction with a smaller system (∼ 3 Gyrs ago)� Strong asymetries found in the young populations.� Shell like structures of young stars (∼ 2− 3Gyrs).� Z = 0.004 for Clump stars (Olszewski et al. 2006).� Random motion kinematic (Walker & Mateo, 2006).


Conclusions

Fornax has been forming stars continiously up to less than 1Gyr.

There exist strong differences as a function of the position.

Last burst located mostly at the center (. 4 Gyrs).Old population uniformly distributed well beyond the core(& 11 Gyrs, z . 0.002).Mean metallicity higher in the innermost regions.

Both, reionization and SNe feedback do not show decisiveeffects.

Our results favored an interaction with a smaller system (∼ 3Gyrs ago), and do not discard a tidal interaction with theMW.


And...

Thank you!


Documents

The early Universe just around the corner: Fornax · PDF fileThe early Universe just around the corner: Fornax dSph ... A unique oportunity ... (km s 1) 55.3 0.1 Luminosity, L V (L