tereza jeŘÁbkovÁ · 2017. 9. 20. · kirk+2012, zonoozi+2016, haghi+2017,romano+(2017) centres...

STELLAR POPULATIONS IN EXTREME STAR BURST CLUSTERS AND ULTRA-COMPACT DWARF GALAXIES (UCD )

TEREZA JEŘÁBKOVÁ ESO GARCHING & UNIVERSITY OF BONN & CHARLES UNIVERSITY IN PRAGUE

MODEST UNDER PRAGUE’S STARRY SKIES CZECH REPUBLIC 18-22 OF SEPTEMBER 2017

www: sirrah.troja.mff.cuni.cz/~tereza email: [email protected]

TH

1

17

s

MOTIVATION STELLAR POPULATIONS WHAT WE CAN SEE NEARBY?

Galactic star forming regions

2

similar environments ( ) and basically solar metallicitywe observe very young objects (formation snapshot)

at similar initial conditions it is difficult to study environmental dependencies of star formation and stellar IMF

BUT

%, T, . . .

s



3

Older objects - Galactic star clusters and GCs and extragalactic UCDs

similar environments ( ) and basically solar metallicity

BUT

most likely formed under different physical conditions compared to local star formation

%, T, . . .

BUT highly evolved systems degenerate with age (initial conditions?)we observe only low mass stars and dynamically evolved systems

s s


we observe very young objects (formation snapshot)



4

Older objects - Galactic star clusters and GCs and extragalactic UCDs

similar environments ( ) and basically solar metallicity

BUT

most likely formed under different physical conditions compared to local star formation

%, T, . . .

BUT highly evolved systems degenerate with agewe observe only low mass stars and dynamically evolved systems

QUESTION: CAN WE OBSERVE PROGENITORS OF GC AND UCD ?s s


we observe very young objects (formation snapshot)

LAYOUT OF THE PROJECT

Jerabkova T., Kroupa P., Dabringhausen J., Hilker M., Bekki K., A&A, 2017, in press

5

https://arxiv.org/abs/1708.07127

Using PEGASE code (Fioc & Rocca-Volmerange 1997)1. Construction of stellar population models for progenitors of UCDs and GCs

Aim: How extreme star formation environments may appear at high redshifts.

(Predictions of observables with James Web Space Telescope)

2. Computation of photometric (magnitudes, colours) and other (SN rates, spectral slopes) diagnostics

With underlying question: Can a systematic variation of the stellar IMF in massive star-bursts be confirmed using observations with the JWST?

+ potential for constraining the formation of multiple stellar populations

see also (Renzini,A&A,2017)

see e.g Glazebrook+(2017,Nat.) & Vanzella+(2017,MNRAS)

https://arxiv.org/abs/1708.07127

ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE

1. Assumption: UCDs and GCs form by monolithic collapse6

(At least some need to Jerabkova +, A&A, 2017)+ formation channel through merged star cluster complexes can be constrained

2. Assumption: Red-shift computed based on CDM and Planck data⇤(Planck Collaboration +, 2016a,b)

3. Assumption: General shape of the IMF: multi-power lawCanonical IMF - nearby star forming regions (Kroupa 2001) - green in all plots

≠1 0 1 2log (m [M§])

≠4

≠2

0

2

log›

(m)[r

elat

ive]

Salpeter slope↵ =2.3

canonical IMF

↵1 = 1.3↵2 = 2.3

↵3 =

2.3

redshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang)


ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE 7

≠1 0 1 2log (m [M§])

≠4

≠2

0

2

log›

(m)[r

elat

ive]

BOTTOM-HEAVY

Salpeter slope

canonical IMF

↵1 = 1.3↵2 = 2.3

↵3 =

2.3

TOP-HEAVYmore massive stars per cluster mass

Top-heavy IMF if: large densities, small [Fe/H]

Bottom-heavy IMF if: metal rich (Marks+2012)

large densities (Conroy & van Dokkum)

Larson (1998), Adams+(1996), Dib+(2007), Papadopoulos (2010) Dabringhausen 2009&2010,Marks+2012, Kirk+2012, Zonoozi+2016, Haghi+2017,Romano+(2017)

centres of ellipticalsChabrier+(2014) - increased density leads to bottom heavy IMFBUT potential problems: Bertelli Motta+(2016), Liptai+(2017)

1. Assumption: UCDs and GCs form by monolithic collapse(At least some need to Jerabkova +, A&A, 2017)

+ formation channel through merged star cluster complexes can be constrained2. Assumption: Red-shift computed based on CDM and Planck data⇤

(Planck Collaboration +, 2016a,b)





≠1 0 1 2log (m [M§])

≠4

≠2

0

2

log›

(m)[r

elat

ive]

BOTTOM-HEAVY

Salpeter slope

canonical IMF

↵1 = 1.3↵2 = 2.3

↵3 =

2.3

TOP-HEAVYmore massive stars per cluster mass

Top-heavy IMF

Bottom-heavy IMF↵1 = ↵2 = ↵3 = 2.3

↵1 = ↵2 = ↵3 = 3.0Dabringhausen+(2008), SAL IMF

van Dokkum&Conroy+(2010), vDC IMF

varies with initial conditionsMarks+(2012), MKDP IMF↵3 < 2.3

CAN IMF↵1 = 1.3, ↵2 = ↵3 = 2.3








SAL IMF vDC IMF MKDP IMFCAN IMFKroupa(2001) Marks+(2012) Dabringhausen+(2008) van Dokkum&Conroy+(2010)




3. Assumption: General shape of the IMF: multi-power lawredshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang)

4. Assumption: other parameterstime grid: (1-10 Myr, 10-100 Myr, 100-1000 Myr, 1-13 Gyr)

Star formation history: simultaneous, constant over 5-10 Myr

initial stellar masses: , SFE = 0.33106, 107, 108, 109 M�Megeath+(2016), Banerjee(2017)

[Fe/H] = -2, 0

PEGASE time-dependent stellar population synthesis code Fioc&Rocca-Volmerange(1997) (comparison with SB99)


RESULTS

For the introduced parameters we construct a grid of SEDs which allow us to construct observables and other characteristic.

10

For the first time we predict how the progenitors of UCDs and massive GCs might look like when formed at high redshifts and compute observability with the JWST.

Luminosity, color-(color)magnitude diagrams, SED slopesMass-to-light ratios, supernovae rates for each set of parameters


103 104 105

⁄ [A]

10≠12

10≠11

F‹[(e

rgs≠

1 cm≠

2 Hz≠

1 )] 6Myr

7Myr

8Myr

9Myr

10Myr

20Myr

MKD IMF

Marks et al. (2012)

?

103 104 105

⁄ [A]

6Myr7Myr8Myr

9Myr10Myr20Myr

CAN IMF

0.0 0.1 0.2mJ ≠mK

6.5

7.0

7.5

8.0

mK≠mN

z=9zoomed plot

tmax|z=9 ¥ 0.6Gyr

0.01 Gyr

0.1 Gyr

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

log(

time[

Myr

])

MKDP IMF vDC IMF

J and K filter cover similar wavelength range as F115W and F200W (NIRCam)

N filter covers similar wavelength range as F1000W (MIRI)

RESULTS: BOLOMETRIC LUMINOSITY 11

100 101 102 103 104

time [Myr]

106

107

108

109

1010

1011

1012

1013

Lbol[L§]

MUCD = 108 M§

Lbol ÃMUCD (NOT for MKDP)

10 7M§

10 8M§

10 9M§

[Fe/H]=≠2

[Fe/H]= 0

MKDP IMFCAN IMFSAL IMFvDC IMF

≠27.5

≠25.0

≠22.5

≠20.0

≠17.5

≠15.0

≠12.5

≠10.0

Mbol[m

ag]

UC

DD

ATA

QUASARS

SUPE

RN

OVA

E

Consistency check

As bright as quasars!

larg

er st

ella

r mas

s

top-

heav

y IM

F

Degeneracies

Supernova explosions may cause photometric variability


age

of th

e sy

stem

RESULTS: COLOR-MAGNITUDE DIAGRAM 12

≠0.5 0.0 0.5 1.0 1.5MV ≠MIc

≠25

≠20

≠15

≠10M

V

vDC IMF109 M§108 M§107 M§

[Fe/H]=0 [Fe/H]=≠2

QUASARS

time

≠0.5 0.0 0.5 1.0 1.5MV ≠MIc

≠25

≠20

≠15

≠10

MV

QUASARS

UC

Dda

taMKDP IMF109 M§108 M§107 M§

time


QSO data: Dunlop+(1993),Dunlop+(2003),Souchay+(2015)high redshift quasars: Morltlock+(2011)

Also colours can be consistent with QSO!

dots/squares: 100 Myr, 500 Myr, 1 Gyr, 5 Gyr, 10 Gyr

RESULTS: MASS-TO-LIGHT RATIOS 13

100 101 102 103 104

time [Myr]

10≠4

10≠3

10≠2

10≠1

100

101

M/L

V

NO remnants10% remnants100% remnants

107 M§ 108 M§ 109 M§[Fe/H]=-2 M

BH

øvDC IMFSAL IMFCAN IMFMKDP IMF

100 101 102 103 104

time [Myr]

10≠4

10≠3

10≠2

10≠1

100

101

M/L

V


107 M§ 108 M§109 M§[Fe/H]=0 M

BH


no degeneracies, t < 100 Myr


SN kicks are not able to remove large fraction of BHs

See our paper (Jerabkova+2017)

and poster: The black hole retention fraction in star clusters (P2)

RESULTS: MASS-TO-LIGHT RATIOS 14

100 101 102 103 104

time [Myr]

10≠4

10≠3

10≠2

10≠1

100

101

M/L

V


107 M§ 108 M§ 109 M§[Fe/H]=-2 M

BH


100 101 102 103 104

time [Myr]

10≠4

10≠3

10≠2

10≠1

100

101

M/L

V


107 M§ 108 M§109 M§[Fe/H]=0 M

BH


no degeneracies, t < 100 Myr


106 107 108

LV [LV§]

5

10

15

20

25

M/L

V

5 Gyr10 Gyr13 Gyr

[Fe/H]=-2vDC IMFSAL IMFMKDP IMF

-10.17 -12.67 -15.17MV [mag]

106 107 108

LV [LV§]

5

10

15

20

25

M/L

V

[Fe/H]= 0

-10.17 -12.67 -15.17MV [mag]

observations

Results are sensitive to [Fe/H]

SN kicks are not able to remove large fraction of BHs

See our paper (Jerabkova+2017)

and poster: The black hole retention fraction in star clusters (P2)

109, 108, 107M�

RESULTS: SUMMARY AND CONCLUSIONS 15


1. Progenitors of UCDs and massive GCs are observable with JWST

2. For objects younger than 100 Myr we can constrain their IMF ( if we observe them)

3. Older objects suffer from degeneracies and constraining the IMF is more difficult

4. Some observed quasars have similar photometric properties as very young UCDs with top-heavy IMF (Are all quasars quasars?)

5. The kick retention fraction of stellar remnants is near to 100% for systems with birth masses larger than 107M�

In prep.: Similar analysis aiming at multiple populations in young GCsCan we disentangle different formation scenarios? What is the effect of binaries?See also: Bekki, Jerabkova, Kroupa, MNRAS, 2017 (variable IMF in GCs)and: Yan, Jerabkova, Kroupa, A&A, 2017 (systematic variation of the IMF in python - on Github)

RESULTS: REDSHIFTED SED 16

J and K filter cover similar wavelength range as F115W and F200W (NIRCam)

103 104 105 106 107

⁄ [A]

10≠33

10≠32

10≠31

10≠30

F‹[(e

rgs≠

1 cm≠

2 Hz≠

1 )]

z=3

z=6

z=9

top-heavy IMF8 Myr

Jfil

t.

Nfil

t.

Kfil

t.

8 Myr

MKD IMF

Marks et al. (2012)

103 104 105 106 107

⁄ [A]

z=3

z=6

z=9

canonical IMF

8 Myr

Jfil

t.

Nfil

t.

Kfil

t.

CAN IMF

N filter covers similar wavelength range as F1000W (MIRI)


RESULTS: FORMATION AND WHERE TO LOOK 17


The most massive clusters are near the centres of galaxies with high star formation rateFerrarese&Merritt (2002), Dabringhausen+(2012), Weidner+(2004), Randriamanakoto+(2013),Li+(2017)

Possible formation scenario

1. Formation of massive galaxies - large star formation rates (large densities, merging of proto-galactic gas clumps)

2. The most massive clusters are forming as monolithically collapsed in the deepest potential wells of these (decouple from gas when become stellar systems)

3. Merging proto-galaxies - many formed clusters ending up on orbits about the central galaxy

4. Under more benign conditions we expect to form stellar systems from mergers of star cluster complexes

tereza jeŘÁbkovÁ · 2017. 9. 20. · kirk+2012, zonoozi+2016, haghi+2017,romano+(2017) centres...

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