Cosmin Ilie Dallas, Dec. 9th, 2013nsm.utdallas.edu/texas2013/proceedings/1/4/g/Ilie.pdf · Cosmin...

Dark Stars and their detectabilityarXiv:1002.2233, 1110.6202

Cosmin Ilie

NASA-CADRE North Carolina Central University, Durham, NC

Dallas, Dec. 9th, 2013

Cosmin Ilie (NCCU) Supermassive Dark Stars Dallas, Dec. 9th, 2013 1 / 32

Outline

1 Introduction

2 Dark Stars Basic Picture

3 Numerical Model

4 Supermassive Dark Stars

5 Detectability of Supermassive Dark Stars

6 Conclusions


Introduction

Outline

1 Introduction


3 Numerical Model



6 Conclusions


Introduction

Cosmological History of the Universe


Introduction

Bird’s Eye View: First Stars Formation

First Luminous Objects.

Forming at the center of DMhaloes of ∼ 106M⊙.

At z = 10− 50.

Halo consists of 85% DM and15% baryons.

Baryons: mainly primordial Hand He.

H2 cooling is the dominantcooling mechanism.

Formation is a gentle process.


Introduction

Dark Matter Heating Effects on Star Formation

First Stars Form in a DMrich environment.

As densities increase →faster DM annihilation.

At critical core densityDM heating dominatesover cooling processes.

DM annihilation energyprevents further collapseof the core.

A “Dark Star” is born


Introduction

Dark Matter Heating Effects on Star Formation

First Stars Form in a DMrich environment.

As densities increase →faster DM annihilation.

At critical core densityDM heating dominatesover cooling processes.

DM annihilation energyprevents further collapseof the core.

A “Dark Star” is born Figure: From Spolyar et al. [2007], arXiv:0705.0521


Introduction

At the moment heating wins:

“Dark Star” supported byDM annihilation ratherthan fusion

They are giant diffuseproto-stars. For 100GeVWIMP core radius is17a.u. and M ∼ 0.6M⊙

DM is only 2% of themass but it provides theheat source.

L ∼ 140L⊙ when they areformed

Figure: Freese et al. ’08. With N. Yoshida


Dark Stars Basic Picture

Outline

1 Introduction


3 Numerical Model



6 Conclusions



Circular Orbits Only and No Capture

D. Spolyar et al., ApJ 705.1031S (2009). Annihilated DM is removed atevery stage

DM supplied via adiabatic contraction (AC). When it runs out →ZAMS.

Massive ∼ 1000M⊙

Large -a few a.u.

Luminous ∼ 107L⊙

Cool: 10, 000K vs. 100, 000K plus → will not reionize the universe

Long lived: ∼ 106yr

With Capture or non circular orbits, could be very different



Capture: More DM

Capture Rate per unit volume: Press, Spergel 85 & Gould 88

dCdV

(r) =(

6π

)1/2n(r)nχ(r)(σc v)

v(r)2

v2

[

1− 1−exp(−B2)B2

]

nχ: number density of DM

n: number density of H

v(r): escape velocity at r .

v : velocity dispersion of WIMPs in the DM halo.For 106M⊙ halo v ∼ 10km/h

σc : scattering cross section.

B2 ∝ v(r)2

v2

Term in the brackets can be neglected because v(R∗) ≫ v .



Minimal Capture case

Average Background DM density≃ 1010GeV /cm3

Adjusted such that as the DS →ZAMS equal contribution from DMheating and fusion

Properties similar to a MainSequence star

Capture does not greatly affect finalmain sequence mass

with capture 787M⊙ vs. withoutcapture 779M⊙

Fig. from Freese et al., New J.Phys.(09)


Numerical Model

Outline

1 Introduction


3 Numerical Model



6 Conclusions


Numerical Model

Equilibrium Structure

Hydrostatic Equilibrium

dPdr

= −ρGMr

r2and dMr

dr= 4πr2ρ(r)

Polytropic Assumption

P = Kρ1+1/n

n = [1.5− 3.0] for Fully Convective/Fully Radiative energy transport

Eq. of state used to solve for temperature

P(r) =Rgρ(r)T (r)

µ + 13aT (r)4

Define Photosphere at optical depth τ ∼ 1

κP = 23g


Numerical Model

Equilibrium Structure cont’d

Thermal equilibrium used to adjust the radius

L∗ = 4πσBR2∗T

4eff = Ltotal

Four possible energy sources

Ltot = LDM + Lgrav + Lnuc + Lcap

In early stages DM heating dominates

LDM = fQ∫

dV 〈σv〉ρ2χ/mχ

Feedback Effects

At Teff > 50, 000K feedback effects invoked.At Teff > 100, 000K accretion is completely turned off.


Supermassive Dark Stars

Outline

1 Introduction


3 Numerical Model



6 Conclusions



Beyond Minimal Capture

Similar Result with Umeda et al.’09

Case “with capture”.σc = 10−39cm3

Results depend only on theproduct σc ρχ

Spin Independent (SI) scattering?Ahmed et al. (09)

For mχ = 100GeVσc,SI < 3.8× 10−44

For mχ ∼ 10GeV SI scatteringcould contribute at high ρχ.



Is there enough DM?

Spherical Halos

DM orbits are planar rosettes (Binney& Tremaine ’08).

The Dark Star creates a loss cone thatcannot be refilled.

Halos are actually Prolate-Triaxial(Bardeen et al. ’86).

Two classes of centrophilic orbits. Boxand Chaotic orbits (Schwarzchild ’79).

Traversing arbitrarily close to thecenter and refilling the loss cone.

The loss cone could remain full for 104

times longer than in the case of aSpherical Halo (Merritt & Poon ’04).


Growth of Central Baryonic Components

Dubinski ’94, Evrad et al. ’94, Debattista et al. ’08

Central Baryonic Components → DM halos more axisymmetric.

Axisymetric models are not expected to contain centrophilic orbits.

Valluri et al. (2010)

Compact central baryonic component grown adiabatically inside a triaxial DM halo→ final halo is nearly oblate.

Yet, a significant fraction (10%) of orbits are centrophilic.

Strong chaotic scattering, a mechanism driving orbits closer to the center.

The more compact the baryonic core → greater fraction of chaotic orbits.

Extended Adiabatic Contraction

We will assume centrophilic orbits provide enough DM to allow the growth of theDS untill possible mergers (10− 100Myrs).

To do: Compute the refill rate of the “loss cone” for SMDS.


H-R diagram for Supermassive Dark Stars

Extended AdiabaticContraction

106M⊙ Halo andM = 10−3M⊙/yr

Extended Capture

σc ρχ = 10−39cm2×1013GeV /cm3

SMDSs are cool and large

Teff ∼< 105K and R∗ ∼ O(10) a.u.


Detectability of Supermassive Dark Stars

Outline

1 Introduction


3 Numerical Model



6 Conclusions



TLUSTY spectra for Dark Stars

SEDs of 106M⊙ SMDS formed via AC.

Teff = 1.9 × 104K. and log10(g/cm s−2)=2.20

SEDs of 106M⊙ SMDS formed “with capture”.


For the case “with capture” Teff is high → most H and He is ionized!



TLUSTY spectra for Dark Stars

H Lyman Break

He I absorption He II absorption

SEDs of 106M⊙ SMDS formed via AC.


SEDs of 106M⊙ SMDS formed “with capture”.


For the case “with capture” Teff is high → most H and He is ionized!


Detectability of Supermassive Dark Stars Using HST data to constrain Dark Stars

Dark Stars as J Band Dropouts (zobs ∼ 10) in HST

Compute apparent magnitudes (mAB) for DS.

Redshift SEDs from TLUSTY ≡ F (λobs ; z)[nJy]Flux reduction (set to zero) at wavelengths shortward of the Ly-α linefor z∼>6.

Using the H and J passbands throughput curves (TH,J(λ)) compute:

mJ,HAB = −2.5 log

(∫

dλTH,J(λ)F (λ; z)∫

dλTH,J(λ)

)

+ 31.4

Dropout selection criterion:

10.5 ∼> z ∼> 9.5 and mHAB −mJ

AB > 1.2



Dark Stars as J Band Dropouts in HST cont’d

Sensitivities from Oesch et al. 2011.In the legend we also list the area of eachsurvey in arcmin2.

J Band dropout criterion: H-J>1.2

The 106M⊙ DS formed via extended AC

could appear as a J Band dropout in the

three HUDF09 surveys.




Sensitivities from Oesch et al. 2011.In the legend we also list the area of eachsurvey in arcmin2


The 106M⊙ DS formed “with captured”

DM could appear as a J Band dropout only

in the deepest HUDF09 survey.






The 107M⊙ DS formed via extended AC

could appear as a J Band dropout in all of

the listed surveys.






The 107M⊙ DS formed “with captured”

DM could appear as a J Band dropout in all

of the listed surveys.



Placing constraints on the Number of Dark Stars

Null detection from HST and bounds on fSMDS :

N =dN

dzdθ2fSMDS(z = zstart)θ

2fsurv f∆t ≤ 1

fSMDS : the fraction of DM halos in the appropriate mass range hosting a DS

θ: angular area of HUDF surveys in which the DS could show as a J Band

dropout.

fsurv : the fraction of DS that survive until the redshift they could be

observed (zobs ∼ 10 in HST).

f∆t : the fraction of the observational window of time ∆t during which theDS is still alive.

For J band dropout: ∆t(10.5− 9.5) = 6.5× 107yr



Host Halos Formation Rates

NBody simulation data from Ilian Iliev and Paul Shapiro.

Parent Halo Formation Rates for MDS =106M⊙ Parent Halo Formation Rates for MDS =107M⊙





Parent Halo Formation Rates for MDS =106M⊙ Parent Halo Formation Rates for MDS =107M⊙

dN

dzdθ2= dn

dt(Vc(zstart + 0.5)− Vc(zstart − 0.5))

C

4π∆t(min;max)





MDS =106M⊙ Case A: zform =10 zstart =10.7 MDS =107M⊙ Case A: zform =10 zstart =13

dN

dzdθ2= dn


C

4π∆t(min;max)





MDS =106M⊙ Case B: zform =12 zstart =12.8 MDS =107M⊙ Case B: zform =12 zstart =16

dN

dzdθ2= dn


C

4π∆t(min;max)





MDS =106M⊙ Case C: zform =15 zstart =16 MDS =107M⊙ Case C: zform =15 zstart ≃20

dN

dzdθ2= dn


C

4π∆t(min;max)





MDS =106M⊙ Case C: zform =15 zstart =16 MDS =107M⊙ Case C: zform =15 zstart ≃20

∆t(min;max) = tH

∫ zstart−.5

zstart+.5

1

(1 + z) (Ωm(1 + z)3 +ΩΛ)12

.


Detectability of Supermassive Dark Stars Predictions for JWST

SMDS in JWST as J115 dropouts ( z∼ 10 detection)

Number of dropouts (N)in a JWST deep fieldsurvey. MDS =106M⊙

“extended AC”

θ2 ≃ 9.68 arcmin2

(instrument FOV)

N ∼< 1.

Similar to HST

null detection





“with capture”

Not detectable as

a J115 dropout for

104s exposures.

Observable if it

survives to z∼< 8





“extended AC”


(instrument FOV)

N ∼< 1.

Similar to HST

null detection





“with capture”


(instrument FOV)

N ∼< 1.

Similar to HST

null detection



SMDS in JWST as H150 dropouts ( z∼ 12 detection)

The MDS =106M⊙

“extended AC”

The DS is

detectable as

dropout at z∼12




Number of H150 dropouts for 106M⊙ SMDS “extended AC”

Nobs = (dN/dzdθ2)fSMDSθ2f∆t

Case I: bounds on fSMDS derived at z∼10 hold at z∼12

NFOVobs ∼< 1 for FOV 9.68 arcmin2 . Nmulti

obs ∼ 10 for θ2 ∼ 150

Case II: relax bounds on fSMDS derived at z∼10

More and longer living DS at higher z

At z∼10 nuclear fusion stars will disrupt DSParent DM Halo Mergers → shorter lifetime of DS

If f∆t =1.5×10−2 at z=10 and f∆t =1 at z=12 →NFOV

obs ∼ 45 and Nmultiobs ∼ 700




The MDS =106M⊙

“with capture”

The DS is notdetectable asdropout at z∼12for 104s exposures.However for 106s:

Case I.NFOV

obs ∼ 2andNmulti

obs ∼ 31Case II.NFOV

obs ∼ 137andNmulti

obs ∼ 2000




The MDS =107M⊙

“extended AC”

Case I.

NFOVobs ∼< 1 and

Nmultiobs ∼ 1

Case II.

NFOVobs ∼ 4 and

Nmultiobs ∼ 64




The MDS =107M⊙

“with capture”

Number of SMDSpredicted in a surveyis identical to the oneMDS =107M⊙

formed by extendedAC.



SMDS in JWST as K200 dropouts ( z∼ 15 detection)

The MDS =106M⊙

“extended AC”.AssumingfSMDS (10)∼fSMDS (15):

Case I.

NFOVobs ∼< 1 and

Nmultiobs ∼ 1

Case II.

NFOVobs ∼ 5 and

Nmultiobs ∼ 75



SMDS in JWST as K200 dropouts ( z∼ 15 detection)

The MDS =107M⊙

“extended AC”

Case I.

NFOVobs ≪ 1 and

Nmultiobs ≪ 1

Case II.

NFOVobs ≪ 1 and

Nmultiobs ∼< 1


Conclusions

Outline

1 Introduction


3 Numerical Model



6 Conclusions


Conclusions

Summary and Conclusions

SMDS are bright enough to be observable even at z∼>20

The lower mass SMDS is more detectable as a dropout

Detection of SMDS at z∼12

Both 106M⊙ and 107M⊙ SMDS have a significant chance of being detected as

H150 dropouts

Detection of SMDS at z∼15

106M⊙ SMDS could still be detected as K200 dropouts. There are too few 107M⊙

SMDS at those redshifts to be detectable as dropouts.

Distinct photometric signatures vs PopIII galaxies

PopIII Type A: red colors in the m356 −m444.

PopIII Type C: steeper slope of UV continuum than extended AC SMDS.Cosmin Ilie (NCCU) Supermassive Dark Stars Dallas, Dec. 9th, 2013 31 / 32

Conclusions

Thank you!


Conclusions

Acknowledgements

We would like to thank to Ilian Iliev and Paul Shapiro for sharing datafrom NBody simulations of cosmic structure formation at high redshift,which we have used to estimate the abundance of host DM halos.


Conclusions

Bibliography I

Greif, T. H., Glover, S. C. O., Bromm, V., & Klessen, R. S. 2010, ApJ,716, 510

Hosokawa, T., Omukai, K., Yoshida, N., & Yorke, H. W. 2011,arXiv:1111.3649, * Temporary entry *

Pawlik, A. H., Milosavljevic, M., & Bromm, V. 2011, Astrophys. J., 731,54

Raiter, A., Schaerer, D., & Fosbury, R. A. E. 2010, A&A, 523, A64+

Schaerer, D. 2002, A&A, 382, 28

Zackrisson, E., Rydberg, C.-E., Schaerer, D., Ostlin, G., & Tuli, M. 2011,ApJ, 740, 13


Conclusions

Protostar Formation in the Early Universe


Conclusions


H2 cooling and colapse

Gas Density:

n ≤ 104 cm−3 Γcool ∼ n2

n ≥ 104 cm−3 Γcool ∼ n

MolecularHAtomicH

∼ 10−3


Conclusions


Cooling

3 Body Reaction:n ≃ 108 cm−3

H + H + H → H2 + H

Becomes FULLY molecular.n ≃ 1010


Conclusions


Cooling to Collapse

Other cooling processes:

n ∼ 1014 cm−3 Collision

Induced Emmisions

n ∼ 1015 cm−3 Dissociation

n ∼ 1018 cm−3 Optically

Thick

Mini Core Forms at n ∼ 1022

cm−3.


Conclusions

Protostellar Feedback and stellar IMF

Credit:NASA / JPL-Caltech / Kyoto Univ.

Hosokawa et al. (2011) hasshown that UV feedback effectsessentially prevent the growth ofthe first stars beyond ∼ 43M⊙

Simulation box 60’000 AU

A pro-star with initial mass ∼ 0.01M⊙

After 20 kyrs, when the star is ∼ 20M⊙, UV

radiation starts to heat the surrounding gas to

T∼> 104K

After 70 kyrs, when the star is ∼ 43M⊙, most of

the gas cloud is evacuated.


Conclusions

Could a DS of M∗ ≃ 103M⊙ be observed with JWST?

Zackrisson et al. (2010),arXiv:1002.3368

Individual DS at z > 6 are toofaint to be detected

Gravitational lensing byforeground galaxy cluster →possible detectability up toz ≃ 10.

If Dark Stars are at least 1%of the total stellar mass of firstgalaxies → distinct signaturesin the integrated spectra


Conclusions

Deep field surveys vs. Gravitational Lensing

Photometric “dropouts” in HubbleUltra Deep Field

Look-back time to most distant object: 12.9-13.1

Gyrs.

Lensing Cluster Abell 383Credit: NASA, ESA, J. Richard, and J.P. Kneib.

Look-back time to lensed galaxy: 12.8 Gyrs.

Mature Stars: Formed when universe was 200 millionyears old!


Conclusions



Credit:Rychard Bouwens





Conclusions

Input parameters

Cosmological

106 − 108M⊙ DM haloes

85% Dark Matter

15% Baryons (X = 0.76,Y = 0.24)

z = 20− 15

Initial NFW profiles with c = 3.5

Use adiabatic contractionBlumenthal et. al [1986] method

Constant accretion rates10−3M⊙/yr − 10−1M⊙/yr

Dark Matter

fQ = 2/3

Ambient DM density:1010Gev/cm3 − 1013GeV /cm3

Scattering Cross Sectionσc = 10−39cm2

mχ = [10GeV , 100GeV , 1TeV ]

Annihilation cross section〈σv〉 = 3× 10−26cm3/s


Conclusions

Hubble Ultra Deep Field cont’d


Conclusions

Detectability with JWST

Black body spectra of two dark stars formed via extended adiabatic contraction.

Fluxes to the left of the Ly-α lines are significantly reduced by IGM absorption for z∼> 6.

107M⊙ DS would be observable in both NIRCam passbands considered. A 105M⊙ DS would be detectable only if it survives

till z∼< 10


Conclusions

Detectability with JWST cont’d

In the “extended capture” case the SMDS is more compact → smallerobserved fluxes


Conclusions

TLUSTY redshifted spectra and NIRCam sensitivities


Conclusions

TLUSTY redshifted spectra cont’d

105M⊙ DS formed at zform =20 in a 106M⊙ DMhalo

105M⊙ DS formed at zform =15 in a 108M⊙ DMhalo


Conclusions



N =dN

dzdθ2fSMDS(z = zstart)θ

2fsurv f∆t ≤ 1

fSMDS : the fraction of DM halos in the appropriate mass range hosting a DS

θ: angular area of HUDF surveys in which the DS could show as a J Band

dropout.

fsurv : the fraction of DS that survive until the redshift they could be

observed (zobs ∼ 10 in HST).

f∆t : the fraction of the observational window of time ∆t during which theDS is still alive.

For J band dropout: ∆t(10.5− 9.5) = 6.5× 107yr


Conclusions



Scenarios Considered

Scenario Name Halo Mass Range zform zstart dn/dt dN

dzdθ2

(M⊙) (Mpc−3yr−1 ) arcmin−2

A.I (1 − 2) × 108 10 13 5 × 10−9 235

B.I (1 − 2) × 108 12 16 7 × 10−10 16

C.I (1 − 2) × 108 15 22 1 × 10−10 0.77

A.I (1 − 2) × 107 10 10.7 5 × 10−8 4435

B.I (1 − 2) × 107 12 12.8 6 × 10−8 2965

C.I (1 − 2) × 107 15 16 2 × 10−8 466


Conclusions




Conclusions

Properties of SMDS

M∗ L∗ R∗ Teff ρc Tc Mχ ρχ,c MAnn

(M⊙) (106L⊙) (AU) (103K) (g/cm3) (105K) (M⊙) (g/cm3) (M⊙)

10 0.13 3.1 4.3 2.8 × 10−7 1.08 0.02 9.2 × 10−10 7 × 10−5

100 1.2 5.2 5.7 7.4 × 10−7 3.4 0.1 1.5 × 10−9 5.6 × 10−3

500 9.7 9.3 7.2 4.3 × 10−6 8.3 0.5 5.8 × 10−9 0.26

103 17 12 7.5 4.6 × 10−6 9.8 0.84 3.3 × 10−10 0.9

104 182 18 10.8 1.3 × 10−5 21 5.3 8.4 × 10−9 86

105 2100 26 16.5 4.1 × 10−5 46 31.2 1.6 × 10−8 10750

Table: Properties and evolution of dark stars for mχ = 100 GeV,

M = 10−3M⊙/yr for the case without capture but with extended adiabaticcontraction. The DM halo was taken to be at a redshift of 20 with aconcentration parameter of 3.5 and with a mass of 106M⊙. Shown are the stellarmass M∗, the DS luminosity L∗, the stellar radius R∗, the surface temperatureTeff , the central baryon density ρc , the central temperature Tc , the amount ofDM in the DS Mχ (due to both adiabatic contraction and capture), the centralWIMP density ρχ,c , and the amount of DM consumed by the DS MAnn.


Conclusions

Properties of SMDS cont’d


(M⊙) (106L⊙) (AU) (103K) (g/cm3) (105K) (M⊙) (g/cm3) (M⊙)

10.0 0.13 3.1 4.3 2.8 × 10−7 1.08 0.02 9.2 × 10−10 4.0 × 10−5

100 1.2 5.1 5.7 7.4 × 10−7 3.5 0.1 1.3 × 10−9 2.7 × 10−3

500 5.5 6.0 7.8 1.6 × 10−5 13 0.3 1.6 × 10−9 0.09

103 8.8 0.3 39 2.9 × 10−1 390 3.1 × 10−6 5.4 × 10−7 0.27

104 161 0.9 47 1.1 × 10−1 440 2.9 × 10−5 1.1 × 10−6 77

105 1950 2.7 50 3.8 × 10−2 450 1.3 × 10−4 3.0 × 10−6 9900

Table: Properties and evolution of dark stars for case “with capture”, formχ = 100 GeV, M = 10−3M⊙/yr, and product of scattering cross section timesambient DM density σc ρχ = 10−39cm2 × 1013 GeV/cm3. The Halo has the sameparameters as in Table 1. The quantities tabulated are the same as in Table 1.The double horizontal line delineates the transition from adiabatically contractedDM to captured DM once the DS reaches ∼ 1000M⊙ (after this point, the DMfrom AC has been annihilated away).


Conclusions

Properties of SMDS cont’d


(M⊙) (106L⊙) (AU) (103K) (g/cm3) (105K) (M⊙) (g/cm3) (M⊙)

12 0.19 3.6 4.3 1.6 × 10−7 0.90 0.03 8.4 × 10−10 1.1 × 10−6

100 1.9 6.5 5.7 3.8 × 10−7 2.7 0.2 1.3 × 10−9 7.6 × 10−5

103 23 15 7.1 2.3 × 10−6 7.8 1.4 4.0 × 10−9 1.2 × 10−2

104 172 28 8.6 3.5 × 10−6 14 9.7 4.3 × 10−9 0.9

105 2100 39 14 1.3 × 10−5 31 56 9.1 × 10−9 109

106 2.2 × 104 61 19 3.3 × 10−5 64 355 1.5 × 10−8 1.1 × 104

107 2.2 × 105 97 27 8.3 × 10−5 127 2200 2.3 × 10−8 1.2 × 106

Table: Properties and Evolution of dark stars for mχ = 100 GeV,

M = 10−1M⊙/yr for the case without capture but with extended adiabaticcontraction. The DM halo was taken to be at a redshift of 15 with aconcentration parameter of 3.5 and with a mass of 108M⊙. The quantitiestabulated are the same as in Table 1.


Conclusions


(M⊙) (106L⊙) (AU) (103K) (g/cm3) (105K) (M⊙) (g/cm3) (M⊙)

11 0.18 3.64 4.3 1.6 × 10−7 0.9 0.03 8.4 × 10−10 5.6 × 10−7

100 1.8 6.5 5.7 3.8 × 10−7 2.7 0.2 1.3 × 10−9 3.8 × 10−5

103 22 14 7.2 2.3 × 10−6 7.8 1.4 3.6 × 10−9 6.1 × 20−3

104 173 23 9.4 5.8 × 10−6 16 8.3 2.9 × 10−9 0.44

4.1 × 104 740 1.8 49 5.7 × 10−2 444 0.18 7.2 × 10−9 6.0

105 1.9 × 103 2.7 51 3.8 × 10−2 452 1.3 × 10−4 2.9 × 10−6 91

106 2.1 × 104 8.5 51 1.2 × 10−2 456 2.7 × 10−5 1.5 × 10−4 1.1 × 104

107 2.1 × 105 27 51 3.9 × 10−3 457 4.0 × 10−10 1.0 × 102 1.1 × 106

Table: Properties and evolution of dark stars for case “with capture”, formχ = 100 GeV, M = 10−1M⊙/yr, and product of scattering cross section timesambient DM density σc ρχ = 10−39cm2 × 1013 GeV/cm3. The DM halo has thesame parameters as in Table 3. The quantities tabulated are the same as in Table1. The double horizontal line delineates the transition from adiabaticallycontracted DM to captured DM once the DS reaches ∼ 4× 104M⊙ (after thispoint, the DM from AC has been annihilated away).


Conclusions

Table: Form Rates

Scenario Name Halo Mass Range zform zstart dn/dt dNdzdθ2

(M⊙) (Mpc−3yr−1 ) arcmin−2

A.I (1− 2)× 108 10 13 5× 10−9 235B.I (1− 2)× 108 12 16 7× 10−10 16C.I (1− 2)× 108 15 22 1× 10−10 0.77A.I (1− 2)× 107 10 10.7 5× 10−8 4435B.I (1− 2)× 107 12 12.8 6× 10−8 2965C.I (1− 2)× 107 15 16 2× 10−8 466

Table: DM halo formation rates: dn/dt expressed in Mpc−3yr−1 , and dNdzdθ2 as

number formed per unit redshift and arcmin2 for cases considered in the text.Values for the first three rows AI-CI are for a 107M⊙ SMDS forming in a (1-2)×108M⊙ DM halo; values for the last three rows, separated by the first three witha horizontal line, are for the 106M⊙ SMDS forming in a (1-2) ×107M⊙ DM halo.We have assumed that the DS started accreting baryons with a constant rate of10−1M⊙/yr at zstart and reached its SMDS mass by zform .


Conclusions

Hubble Ultra Deep Field


Conclusions

PopIII galaxies Yggdrasil model grids

We used the Yggdrasil model grids (Zackrisson et al., 2011) found athttp://ttt.astro.su.se/~ez/. Initial Mass Function (IMF) for PopIII galaxiesconsidered:

PopIII.1: Z=0 population with an extremely top heavy IMF and a Single StellarPopulation (SSP) from Schaerer (2002). Stellar masses: 50− 500M⊙ with aSalpeter slope.

PopIII.2: Z=0 population with a moderately top-heavy IMF. The characteristicmass is 10 M⊙. Wings of the mass function extend from 1 to 500M⊙. A SSPfrom Raiter et al. (2010) is used.

PopIII, Kroupa IMF: In view of recent simulations (e.g. Greif et al., 2010) the massof PopIII stars might be lower than previously predicted → normal Kroupa IMFwith stellar masses ranging in the 0.1− 100M⊙. SSP is a rescaled version of theone used in Schaerer (2002)

The nebular emission dominates the spectrum of PopIII galaxies even at z∼ 10− 15(Zackrisson et al., 2011) if tey are younger than ∼ 107 yrs. Cases for fcov considered:

Type A galaxies: fcov = 1, implying maximal nebular contribution to the SED andno escape of Lyman continuum photons.

Type C galaxies: fcov = 0, where there is no nebular contribution to the SEDs.


http://ttt.astro.su.se/~ez/

Conclusions

Detectability of PopIII galaxies and SMDS with JWST

For the PopIII galaxies we use the Yggdrasil model grids of Zackrisson et al. (2011). At z∼ 10 JWST could detect 105M⊙

stellar mass PopIII galaxies (Pawlik et al., 2011)


Conclusions

Colors of SMDS vs PopIII inst. burst galaxies in NIRCam

At z∼12 NIRCam is sensitive to λrest = [0.1216, 0.384]µm. Lyαabsorption renders fluxes to zero for λrest ∼< 0.1216µm

Features of the PopIII type A galaxies spectra in that interval:

The HeII line at 0.1640µm. Appears in F200W

The continuum limit of the Balmer series. Appears in F444W.

The slope of the UV continuum can be measured using F277W andF356W.


Conclusions



Conclusions


Differences

For the SMDS spectra we consider no nebular emission as they are cooland most of the baryons are already accreted onto the core.

The absence of recombination lines for SMDS → clustered close aline of slope 1 on the third quadrant of the color diagrams.


PopIII Type C: steeper slope of UV continuum than SMDS formed viaextended AC.

Difficult to differentiate SMDS formed “with capture” and Type CPopIII galaxies


Conclusions

PopIII galaxies Yggdrasil model grids

We used the Yggdrasil model grids (Zackrisson et al., 2011) found athttp://ttt.astro.su.se/~ez/. Initial Mass Function (IMF) for PopIII galaxiesconsidered:

PopIII.1: Z=0 population with an extremely top heavy IMF and a Single StellarPopulation (SSP) from Schaerer et al. 2002. Stellar masses: 50− 500M⊙ with aSalpeter slope.

PopIII.2: Z=0 population with a moderately top-heavy IMF. The characteristicmass is 10 M⊙. Wings of the mass function extend from 1 to 500M⊙. A SSPfrom Raiter et al. (2010) is used.

PopIII, Kroupa IMF: In view of recent simulations (e.g. Greif et al., 2010) the massof PopIII stars might be lower than previously predicted → normal Kroupa IMFwith stellar masses ranging in the 0.1− 100M⊙. SSP is a rescaled version of theone used in Schaerer (2002)

The nebular emission dominates the spectrum of PopIII galaxies even at z∼ 10− 15(Zackrisson et al., 2011) if tey are younger than ∼ 107 yrs. Cases for fcov considered:

Type A galaxies: fcov = 1, implying maximal nebular contribution to the SED andno escape of Lyman continuum photons.

Type C galaxies: fcov = 0, where there is no nebular contribution to the SEDs.


http://ttt.astro.su.se/~ez/

Conclusions

Detectability of PopIII galaxies and SMDS with JWST

For the PopIII galaxies we use the Yggdrasil model grids of Zackrisson et al. (2011). At z∼ 10 JWST could detect 105M⊙Cosmin Ilie (NCCU) Supermassive Dark Stars Dallas, Dec. 9th, 2013 56 / 32

Conclusions


At z∼12 NIRCam is sensitive to λrest = [0.1216, 0.384]µm. Lyαabsorption renders fluxes to zero for λrest ∼< 0.1216µm

Features of the PopIII type A galaxies spectra in that interval:

The HeII emission line at 0.1640µm. Appears in F200W

The Balmer edge. Appears in F444W.

The slope of the UV continuum ( fλ ∝ λβ) can be measured usingF277W and F356W:

β =1

2.5 logλpivot;F356W

λpivot;F277W

(m277 −m356)− 2.0,


Conclusions



Conclusions


Differences

For the SMDS spectra we consider no nebular emission as they are cooland most of the baryons are already accreted onto the core.

The absence of recombination lines for SMDS → clustered close aline of slope 1 on the third quadrant of the color diagrams.


PopIII Type C: steeper slope of UV continuum than SMDS formed viaextended AC.

Difficult to differentiate SMDS formed “with capture” and Type CPopIII galaxies


Conclusions



Look-back time to most distant object: 12.9-13.1

Gyrs.





Conclusions



Credit:Rychard Bouwens





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