Improper desire

Davidson, Harriet J.

doi:10.1017/ccol0521420806.009

Cited by 13 publications

(7 citation statements)

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“…For the QCD axion, we obtain M 0 5×10 −10 M based on the axion mass parameterization used in Buschmann et al (2019) and the the effective number of relativistic degrees of freedom presented by Husdal (2016) (see Appendix A). After accounting for a factor of 4 π 4 /3 ≈ 130 larger in our definition, this number is compatible with the characteristic masses for the first gravitationally collapsed axion minihalos quoted in other references (Davidson & Schwetz 2016;Hardy 2017;Fairbairn et al 2018). We therefore estimate that the typical mass for the first collapsed axion minihalos is ∼ 0.01 M 0 , and is ∼ 5 × 10 −12 M for QCD axions.…”

Section: Isocurvature Density Fluctuations In Axion Cosmologysupporting

confidence: 85%

“…We note that our definition of M 0 is adopted from Fairbairn et al (2018), which is a factor 4 π 4 /3 larger than what is used in several other references (e.g. Davidson & Schwetz 2016;Hardy 2017). Following the definition of the latter authors, the typical mass for the smallest minihalos that collapse the earliest from gravitational instability should be two orders of magnitude smaller than M 0 .…”

Section: Resultsmentioning

confidence: 98%

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Gravitational Lensing Signatures of Axion Dark Matter Minihalos in Highly Magnified Stars

Dai

Miralda-Escudé

2020

122

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Axions are a viable candidate for Cold Dark Matter (CDM) which should generically form minihalos of sub-planetary masses from white-noise isocurvature density fluctuations if the Peccei-Quinn phase transition occurs after inflation. Despite being denser than the larger halos formed out of adiabatic fluctuations from inflation, axion minihalos have surface densities much smaller than the critical value required for gravitational lensing to produce multiple images or high magnification, and hence are practically undetectable as lenses in isolation. However, their lensing effect can be enhanced when superposed near critical curves of other lenses. We propose a method to detect them through photometric monitoring of recently discovered caustic transiting stars behind cluster lenses, under extreme magnification factors µ 10 3 -10 4 as the lensed stars cross microlensing caustics induced by intracluster stars. For masses of the first gravitationally collapsed minihalos in the range ∼ 10 −15 -10 −8 h −1 M , we show that axion minihalos in galaxy clusters should collectively produce subtle surface density fluctuations of amplitude ∼ 10 −4 -10 −3 on projected length scales of ∼ 10-10 4 AU, which imprint irregularities in the microlensing light curves of caustic transiting stars. We estimate that, inside a cluster halo and over the age of the Universe, most of these minihalos are likely to avoid dynamic disruption by encounters with stars or other minihalos.

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Section: Isocurvature Density Fluctuations In Axion Cosmologysupporting

confidence: 85%

Section: Resultsmentioning

confidence: 98%

Gravitational Lensing Signatures of Axion Dark Matter Minihalos in Highly Magnified Stars

Dai

Miralda-Escudé

2020

122

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“…When this happens, the commonly made assumption that the axion fluid obeys classical field equations is unjustified. Classical field equations are still valid, of course, as a description of stable or metastable objects in the axion fluid such as flat domain walls [13], straight strings [14] and Bose stars [15], [6], [7], [16] since thermalization plays no role for them.…”

mentioning

confidence: 99%

Duration of classicality in highly degenerate interacting Bosonic systems

Sikivie

Todarello

2017

Physics Letters B

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“…For some references on possible consequences and observations connected with axion miniclusters and axion stars see refs. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], and for work on their structure and stability see refs [23,41,[45][46][47][48][49][50][51][52]. For work on the possible unique signatures of axion structure formation due to their quantum mechanical properties as light degenerate bosons see refs.…”

Section: Introductionmentioning

confidence: 99%

Axion cosmology with early matter domination

Nelson

Xiao

2018

Phys. Rev. D

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The default assumption of early universe cosmology is that the postinflationary universe was radiation dominated until it was about 47000 years old. Direct evidence for the radiation dominated epoch extends back until nucleosynthesis, which began during the first second. However there are theoretical reasons to prefer a period of earlier matter domination, prior to nucleosynthesis, e.g. due to late decaying massive particles needed to explain baryogenesis. Axion cosmology is quantitatively affected by an early period of matter domination, with a different axion mass range preferred and greater inhomogeneity produced on small scales. In this work we show that such increased inhomogeneity can lead to the formation of axion miniclusters in axion parameter ranges that are different from those usually assumed. If the reheating temperature is below 58 MeV, axion miniclusters can form even if the axion field is present during inflation and has been previously homogenized. The upper bound on the typical initial axion minicluster mass is raised from 10 −10 M⊙ to 10 −7 M⊙, where M⊙ is a solar mass. These results may have consequences for indirect detection of axion miniclusters, and could conceivably probe the thermal history of the universe before nucleosynthesis.PACS numbers:

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Improper desire

Cited by 13 publications

References 0 publications

Gravitational Lensing Signatures of Axion Dark Matter Minihalos in Highly Magnified Stars

Gravitational Lensing Signatures of Axion Dark Matter Minihalos in Highly Magnified Stars

Duration of classicality in highly degenerate interacting Bosonic systems

Axion cosmology with early matter domination

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