Constraining White Dwarf Structure and Neutrino Physics in 47 Tucanae

Goldsbury, Ryan; Richer, Harvey B.; Kalirai, Jason; Tremblay, Pier-Emmanuel

doi:10.3847/0004-637x/821/1/27

Cited by 11 publications

(17 citation statements)

References 33 publications

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“…Bottom: UV data used in this paper. Artificial star tests described in Goldsbury et al (2016). match the stars between the F336W and F475W images, providing a baseline of ∼ 11 yr over which to calculate proper motions.…”

Section: Proper Motionsmentioning

confidence: 99%

“…Figure 1 displays the higher core completeness of the bluer filters. For a detailed description of the observations and completeness correction process, see Goldsbury et al (2016).…”

Section: Proper Motionsmentioning

confidence: 99%

“…The large number of predicted low-mass WD progenitors does agree with observed WD counts when one considers the WD birth rate, the time a WD takes to cool below detection thresholds, and the age of the cluster (Goldsbury et al 2016). Completeness corrections were done with artificial star tests (also see Goldsbury et al 2016) est mass functions, and assuming some fraction of the 0.85 M stars have been lost would only serve to raise the IMF and increase the remnant estimates. By keeping our estimates conservative the final predicted IMBH mass is likely to be an overestimate, as there is potentially more remnant mass that we have not accounted for.…”

Section: Stellar Remnantsmentioning

confidence: 99%

“…Furthermore, we ignore the constant offset introduced to the ln L value by Gaussian normalization. For a full derivation and explanation of the entire unbinned likelihood technique, see Goldsbury et al (2016). The specific parameters that went into our model are shown in Table 2 and the resulting velocity dispersion profiles are plotted in Figure 6.…”

Section: Binned Vs Unbinned Analysismentioning

confidence: 99%

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A Multimass Velocity Dispersion Model of 47 Tucanae Indicates No Evidence for an Intermediate-mass Black Hole

Mann

Richer

Heyl

et al. 2019

ApJ

139

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In this paper, we analyze stellar proper motions in the core of the globular cluster 47 Tucanae to explore the possibility of an intermediate-mass black hole (IMBH) influence on the stellar dynamics. Our use of short-wavelength photometry affords us an exceedingly clear view of stellar motions into the very center of the crowded core, yielding proper motions for >50,000 stars in the central 2 . We model the velocity dispersion profile of the cluster using an isotropic Jeans model. The density distribution is taken as a central IMBH point mass added to a combination of King templates. We individually model the general low-mass cluster objects (main-sequence/giant stars), as well as the concentrated populations of heavy binary systems and dark stellar remnants. Using unbinned likelihood model fitting, we find that the inclusion of the concentrated populations in our model plays a crucial role in fitting for an IMBH mass. The concentrated binaries and stellar-mass black holes (BHs) produce a sufficient velocity dispersion signal in the core so as to make an IMBH unnecessary to fit the observations. We additionally determine that a stellar-mass BH retention fraction of 8.5% becomes incompatible with our observed velocities in the core.

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Section: Proper Motionsmentioning

confidence: 99%

“…Figure 1 displays the higher core completeness of the bluer filters. For a detailed description of the observations and completeness correction process, see Goldsbury et al (2016).…”

Section: Proper Motionsmentioning

confidence: 99%

Section: Stellar Remnantsmentioning

confidence: 99%

Section: Binned Vs Unbinned Analysismentioning

confidence: 99%

See 2 more Smart Citations

A Multimass Velocity Dispersion Model of 47 Tucanae Indicates No Evidence for an Intermediate-mass Black Hole

Mann

Richer

Heyl

et al. 2019

ApJ

139

View full text Add to dashboard Cite

show abstract

“…Furthermore, if DFSZ axions exist and have masses in the range of a few meV, as suggested by this study, they will introduce subtle but detectable changes in the evolution of stars as is the case of red giants (Viaux et al 2013), horizontal branch stars (Ayala et al 2014), and globular clusters (Hansen et al 2015;Goldsbury et al 2012Goldsbury et al , 2016. Additionally, it is expected that the direct measurement of the characteristic cooling time of white dwarfs employing the secular variation of the pulsation periods of ZZ Ceti stars will be much improved in a near future (Córsico et al 2012a(Córsico et al ,b, 2016.…”

Section: Results and Conclusionmentioning

confidence: 74%

Axions and the luminosity function of white dwarfs: the thin and thick discs, and the halo

Isern

Garcı́a–Berro

Torres

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The evolution of white dwarfs is a simple gravothermal process of cooling. Since the shape of their luminosity function is sensitive to the characteristic cooling time, it is possible to use its slope to test the existence of additional sources or sinks of energy, such as those predicted by alternative physical theories. The aim of this paper is to study if the changes in the slope of the white dwarf luminosity function around bolometric magnitudes ranging from 8 to 10 and previously attributed to axion emission are, effectively, a consequence of the existence of axions and not an artifact introduced by the star formation rate. We compute theoretical luminosity functions of the thin and thick disk, and of the stellar halo including axion emission and we compare them with the existing observed luminosity functions. Since these stellar populations have different star formation histories, the slope change should be present in all of them at the same place if it is due to axions or any other intrinsic cooling mechanism. The signature of an unexpected cooling seems to be present in the luminosity functions of the thin and thick disks, as well as in the halo luminosity function. This additional cooling is compatible with axion emission, thus supporting to the idea that DFSZ axions, with a mass in the range of 4 to 10 meV, could exist. If this were the case, these axions could be detected by the future solar axioscope IAXO.

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Could compact stars in globular clusters constrain dark matter?

Garani

Raj

Reynoso-Cordova

2023

J. Cosmol. Astropart. Phys.

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The dark matter content of globular clusters, highly compact gravity-bound stellar systems, is unknown. It is also generally unknowable, due to their mass-to-light ratios typically ranging between 1-3 in solar units, accommodating a dynamical mass of dark matter at best comparable to the stellar mass. That said, recent claims in the literature assume densities of dark matter around 1000 GeV/cm3 to set constraints on its capture and annihilation in white dwarfs residing in the globular cluster M4, and to study a number of other effects of dark matter on compact stars. Motivated by these studies, we use measurements of stellar kinematics and luminosities in M4 to look for a dark matter component via a spherical Jeans analysis; we find no evidence for it, and set the first empirical limits on M4's dark matter distribution. Our density upper limits, a few × 104 GeV/cm3 at 1 parsec from the center of M4, do not negate the claims (nor confirm them), but do preclude the use of M4 for setting limits on non-annihilating dark matter kinetically heating white dwarfs, which require at least 105 GeV/cm3 densities. The non-robust nature of globular clusters as dynamical systems, combined with evidence showing that they may originate from molecular gas clouds in the absence of dark matter, make them unsuitable as laboratories to unveil dark matter's microscopic nature in current or planned observations.

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Constraining White Dwarf Structure and Neutrino Physics in 47 Tucanae

Cited by 11 publications

References 33 publications

A Multimass Velocity Dispersion Model of 47 Tucanae Indicates No Evidence for an Intermediate-mass Black Hole

A Multimass Velocity Dispersion Model of 47 Tucanae Indicates No Evidence for an Intermediate-mass Black Hole

Axions and the luminosity function of white dwarfs: the thin and thick discs, and the halo

Could compact stars in globular clusters constrain dark matter?

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