Recombinational lines of P(S) (Positronium) as tracer of annihilation processes

Burdyuzha, V. V.; Kauts, V. L.

doi:10.1086/192013

Cited by 5 publications

(3 citation statements)

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“…Ps atoms, which consist of an electron and a positron , can be formed from an hydrogen (H) plasma once energy losses in the interstellar medium have reduced the gas temperature to (Burdyuzha & Kauts 1994). At these temperatures, Ps can form from recombination of electrons and positrons, or by charge exchange of positrons with H and other atoms and molecules with the relative formation rates being extremely sensitive to temperature and density (Bussard, Ramaty, & Drachman 1979).…”

Section: Positronium (Ps) Recombinationmentioning

confidence: 99%

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

Bond

Bekki

Westmeier

2022

Publ. Astron. Soc. Aust.

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A plausible formation scenario for the Galactic globular clusters 47 Tucanae (47 Tuc) and Omega Centauri $(\omega$ Cen) is that they are tidally stripped remnants of dwarf galaxies, in which case they are likely to have retained a fraction of their dark matter cores. In this study, we have used the ultra-wide band receiver on the Parkes telescope (Murriyang) to place upper limits on the annihilation rate of exotic Light Dark Matter particles $(\chi)$ via the $\chi\chi\rightarrow e^+e^-$ channel using measurements of the recombination rate of positronium (Ps). This is an extension of a technique previously used to search for Ps in the Galactic Centre. However, by stacking of spectral data at multiple line frequencies, we have been able to improve sensitivity. Our measurements have resulted in $3-\sigma$ flux density (recombination rate) upper limits of 1.7 mJy $\left(1.4\times 10^{43}\, \mathrm{s}^{-1}\right)$ and 0.8 mJy $\left(1.1 \times 10^{43} \mathrm{s}^{-1}\right)$ for 47 Tuc and $\omega$ Cen, respectively. Within the Parkes beam at the cluster distances, which varies from 10–23 pc depending on the frequency of the recombination line, and for an assumed annihilation cross-section $\langle\sigma v\rangle = 3\times 10^{-29} \mathrm{cm}^3\, \mathrm{s}^{-1}$ , we calculate upper limits to the dark matter mass and rms dark matter density of ${\lesssim} 1.2-1.3\times 10^5 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot}$ and ${\lesssim} 48-54 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot} \mathrm{pc}^{-3}$ for the clusters, where $f_n=R_n/R_p$ is the ratio of Ps recombination transitions to annihilations, estimated to be ${\sim}0.01$ . The radio limits for $\omega$ Cen suggest that, for a fiducial dark/luminous mass ratio of ${\sim}0.05$ , any contribution from Light Dark Matter is small unless $\langle\sigma v\rangle < 7.9\times 10^{-28}\ \left(m_\chi/\mathrm{MeV\, c}^{-2}\right)^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Owing to the compactness and proximity of the clusters, archival 511-keV measurements suggest even tighter limits than permitted by CMB anisotropies, $\langle\sigma v\rangle < 8.6\times 10^{-31}\ (m_\chi/\mathrm{MeV\, c}^{-2})^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Due to the very low synchrotron radiation background, our recombination rate limits substantially improve on previous radio limits for the Milky Way.

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Section: Positronium (Ps) Recombinationmentioning

confidence: 99%

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

Bond

Bekki

Westmeier

2022

Publ. Astron. Soc. Aust.

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“…Ps atoms, which consist of an electron (e -) and a positron (e + ), can be formed from an e -/e + /hydrogen (H) plasma once energy losses in the interstellar medium have reduced the gas temperature to T k < 10 6 K (Burdyuzha & Kauts, 1994). At these temperatures, Ps can form from recombination of electrons and positrons, or by charge exchange of positrons with H and other atoms and molecules, with the relative formation rates being extremely sensitive to temperature and density (Bussard et al, 1979).…”

Section: Positronium (Ps) Recombinationmentioning

confidence: 99%

A Search for Annihilating Dark Matter in 47 Tucanae and Omega Centauri

Staveley-Smith,

Bond,

Bekki

et al. 2022

Preprint

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A plausible formation scenario for the Galactic globular clusters 47 Tucanae (47 Tuc) and Omega Centauri (ω Cen) is that they are tidally stripped remnants of dwarf galaxies, in which case they are likely to have retained a fraction of their dark matter cores. In this study, we have used the ultra-wide band receiver on the Parkes telescope (Murriyang) to place upper limits on the annihilation rate of exotic Light Dark Matter particles (χ) via the χχ → e + echannel using measurements of the recombination rate of positronium (Ps). This is an extension of a technique previously used to search for Ps in the Galactic Centre. However, by stacking of spectral data at multiple line frequencies, we have been able to improve sensitivity. Our measurements have resulted in 3-σ flux density (recombination rate) upper limits of 1.7 mJy (1.4 × 10 43 s -1 ) and 0.8 mJy (1.1 × 10 43 s -1 ) for 47 Tuc and ω Cen, respectively. Within the Parkes beam at the cluster distances, which varies from 10-23 pc depending on the frequency of the recombination line, and for an assumed annihilation cross section σv = 3 × 10 -29 cm 3 s -1 , we calculate upper limits to the dark matter mass and rms dark matter density of 1.2 -1.3 × 10 5 f -0.5 n (mχ/MeV c -2 ) M and 48 -54f -0.5 n (mχ/MeV c -2 ) M pc -3 for the clusters, where fn = Rn/Rp is the ratio of Ps recombination transitions to annihilations, estimated to be ∼ 0.01. The radio limits for ω Cen suggest that, for a fiducial dark/luminous mass ratio of ∼ 0.05, any contribution from Light Dark Matter is small unless σv < 7.9 × 10 -28 (mχ/MeV c -2 ) 2 cm 3 s -1 . Owing to the compactness and proximity of the clusters, archival 511-keV measurements suggest even tighter limits than permitted by CMB anisotropies, σv < 8.6 × 10 -31 (mχ/MeV c -2 ) 2 cm 3 s -1 . Due to the very low synchrotron radiation background, our recombination rate limits substantially improve on previous radio limits for the Milky Way.

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“…Finally, Ps annihilates via 2 photon (511 keV) emission from the singlet S-state or via 3 photon (continuum 0 to 511 keV) emission from the triplet S-state. Probabilities of annihilation are [9,11]:…”

Section: A Laboratory Positroniummentioning

confidence: 99%

<i>L<sub>α</sub></i> Line of Dark Positronium as a Nongravitational Detection of DM

Burdyuzha¹,

Charugin²

2015

JMP

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An attempt to predict the new atomic dark matter lines is done on the example of a dark lepton atompositronium. Its Layman-alpha line with the energy near 3 GeV may be observable if the appropriate conditions realize. For this we have studied a γ-ray excess in the Center of our Galaxy. In principle, this excess may be produced by the L α line of a dark positronium in the medium with Compton scattering. The possibility of observations of an annihilation line (E~300 TeV) of dark positronium is also predicted. Other proposals to observe the atomic dark matter are shortly described. Besides, H α line (1.3μ) of usual positronum must be observable in the direction on the Center of our Galaxy.

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Recombinational lines of P(S) (Positronium) as tracer of annihilation processes

Cited by 5 publications

References 0 publications

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

A Search for Annihilating Dark Matter in 47 Tucanae and Omega Centauri

<i>L<sub>α</sub></i> Line of Dark Positronium as a Nongravitational Detection of DM

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Recombinational lines of P(S) (Positronium) as tracer of annihilation processes

Cited by 5 publications

References 0 publications

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

A Search for Annihilating Dark Matter in 47 Tucanae and Omega Centauri

&lt;i&gt;L&lt;sub&gt;α&lt;/sub&gt;&lt;/i&gt; Line of Dark Positronium as a Nongravitational Detection of DM

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<i>L<sub>α</sub></i> Line of Dark Positronium as a Nongravitational Detection of DM