J/ApJ/733/L51 Dark matter densities in cluster isochrones (Casanellas+, 2011)
Signatures of dark matter burning in nuclear star clusters.
Casanellas J., Lopes I.
<Astrophys. J., 733, L51 (2011)>
=2011ApJ...733L..51C 2011ApJ...733L..51C
ADC_Keywords: Clusters, open ; Models ; Isochrones
Keywords: dark matter - Hertzsprung-Russell and C-M diagrams - Galaxy: center -
galaxies: star clusters: general - stars: fundamental parameters
Abstract:
In order to characterize how dark matter (DM) annihilation inside
stars changes the aspect of a stellar cluster, we computed the
evolution until the ignition of the He burning of stars from
0.7M☉ to 3.5M☉ within halos of DM with different
characteristics. We found that, when a cluster is surrounded by a
dense DM halo, the positions of the cluster' stars in the H-R
diagram have a brighter and hotter turnoff point than in the classical
scenario without DM, therefore giving the cluster a younger
appearance. The high DM densities required to produce these effects
are expected only in very specific locations, such as near the center
of our Galaxy. In particular, if DM is formed by the 8 GeV weakly
interacting massive particles recently invoked to reconcile the
results from direct detection experiments, then this signature is
predicted for halos of DM with a density
ρχ=3x105GeV/cm3. A DM density gradient inside the
stellar cluster would result in a broader main sequence, turnoff, and
red giant branch regions. Moreover, we found that for very high DM
halo densities the bottom of the isochrones in the H-R diagram rises
to higher luminosities, leading to a characteristic signature on the
stellar cluster. We argue that this signature could be used to
indirectly probe the presence of DM particles in the location of a
cluster.
Description:
To compute our stellar models we used the stellar evolution code CESAM
(Morel 1997A&AS..124..597M 1997A&AS..124..597M). See section 2.
Table 1 shows a summary of the data used in Figures 2 and 3, which
corresponds to the isochrones of a classical stellar cluster and of
stellar clusters embedded in halos of dark matter (DM) particles with
densities ρχ=109GeV/cm3 and ρχ=1010GeV/cm3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 40 992 Isochrones of stellar clusters embedded in halos
of dark matter particles with different dark
matter densities
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See also:
J/ApJ/717/257 : Synthetic spectra of dark stars (Zackrisson+, 2010)
J/ApJ/703/1323 : Stars in the Galaxy's nuclear cluster (Do+ 2009
J/A+A/499/483 : NIR obs. of sources in galactic center (Buchholz+, 2009)
J/A+AS/141/371 : Low-mass stars evolutionary tracks+isochrones (Girardi+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 E7.1 GeV/cm3 rho [0,1.e10] Dark matter density ρ (1)
9- 13 I5 Myr Age [25/13000] Isochrone age
15 A1 --- f_Age [a] conservative estimation of Age (2)
17- 23 F7.5 Msun Mass [0.7/3.5] Isochrone mass
25- 31 F7.5 [K] logT log of the isochrone effective temperature
33- 40 F8.5 [Lsun] logL log of the isochrone luminosity
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Note (1): The dark matter particles are assumed to have a mass of 100GeV
and a spin-dependent (SD) scattering cross section with protons
σ(χ,SD)=10-38cm-2. The values are 0, 109 or 1010.
Note (2): In the case of {rho=}1010GeV/cm3, the post-MS segment of the
10Gyr isochrone is a conservative estimation (a lower limit on
luminosity) of the true isochrone. It corresponds to the evolutionary
track of a star of 1.482MSun.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 19-Nov-2012