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285 results on '"Bond, Emma"'

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

Author

Staveley-Smith, Lister, Bond, Emma, Bekki, Kenji, and Westmeier, Tobias

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

A plausible formation scenario for the Galactic globular clusters 47 Tuc and 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 (X) via the XX/$e^+e^-$ 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 (1.4x10$^{43}$ s$^{-1}$) and 0.8 mJy (1.1x10$^{43}$ s$^{-1}$) for 47 Tuc and Omega Cen, respectively. Within the Parkes beam at the cluster distances, which varies from 10 to 23 pc depending on the frequency of the recombination line, we calculate upper limits to the dark matter mass and rms dark matter density of <1.2-1.3x10$^5$ fn$^{-0.5}$ (mX/MeV c$^{-2}$) solar masses and <48-54 fn$^{-0.5}$ (mX/MeV c$^{-2}$) solar masses 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 Omega Cen suggest that, for a fiducial dark/luminous mass ratio of 0.05, any contribution from Light Dark Matter is small unless the cross section <7.9x10$^{-28}$ (mX/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, <8.6x10$^{-31}$ (mX/MeV c$^{-2}$)$^2$ cm$^3$ s$^{-1}$. Our recombination rate limits substantially improve on previous radio limits for the Milky Way., Comment: 11 pages, 4 figures, 3 tables; accepted by Publications of the Astronomical Society of Australia 2 May 2022; abbreviated arXiv abstract; minor corrections to match proofs; CUP open source publication

Published
2022
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5. A Progressive Future?

Author

Phippen, Andy, Bond, Emma, Aston, Elizabeth, Series Editor, Rowe, Michael, Series Editor, Phippen, Andy, and Bond, Emma

Published
2023
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7. Legal Challenges

Author

Phippen, Andy, Bond, Emma, Aston, Elizabeth, Series Editor, Rowe, Michael, Series Editor, Phippen, Andy, and Bond, Emma

Published
2023
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10. Introduction

Author

Phippen, Andy, Bond, Emma, Aston, Elizabeth, Series Editor, Rowe, Michael, Series Editor, Phippen, Andy, and Bond, Emma

Published
2023
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12. Fighting the Tide—GPT and an Alarming Sense of Déjà Vu

Author

Phippen, Andy, Bond, Emma, Masys, Anthony J., Editor-in-Chief, Bichler, Gisela, Advisory Editor, Bourlai, Thirimachos, Advisory Editor, Johnson, Chris, Advisory Editor, Karampelas, Panagiotis, Advisory Editor, Leuprecht, Christian, Advisory Editor, Morse, Edward C., Advisory Editor, Skillicorn, David, Advisory Editor, Yamagata, Yoshiki, Advisory Editor, Jahankhani, Hamid, editor, Jamal, Arshad, editor, Brown, Guy, editor, Sainidis, Eustathios, editor, Fong, Rose, editor, and Butt, Usman J., editor

Published
2023
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36. Image Recognition in Child Sexual Exploitation Material—Capabilities, Ethics and Rights

Author

Phippen, Andy, Bond, Emma, Masys, Anthony J., Series Editor, Bichler, Gisela, Advisory Editor, Bourlai, Thirimachos, Advisory Editor, Johnson, Chris, Advisory Editor, Karampelas, Panagiotis, Advisory Editor, Leuprecht, Christian, Advisory Editor, Morse, Edward C., Advisory Editor, Skillicorn, David, Advisory Editor, Yamagata, Yoshiki, Advisory Editor, Jahankhani, Hamid, editor, Akhgar, Babak, editor, Cochrane, Peter, editor, and Dastbaz, Mohammad, editor

Published
2020
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37. Tackling Teen Sexting—Policing Challenges When Society and Technology Outpace Legislation

Author

Bond, Emma, Phippen, Andy, Masys, Anthony J., Series Editor, Bichler, Gisela, Advisory Editor, Bourlai, Thirimachos, Advisory Editor, Johnson, Chris, Advisory Editor, Karampelas, Panagiotis, Advisory Editor, Leuprecht, Christian, Advisory Editor, Morse, Edward C., Advisory Editor, Skillicorn, David, Advisory Editor, Yamagata, Yoshiki, Advisory Editor, Jahankhani, Hamid, editor, Akhgar, Babak, editor, Cochrane, Peter, editor, and Dastbaz, Mohammad, editor

Published
2020
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42. Afterword

Author

Bond, Emma, Aguiar, Marian, Series Editor, Mathieson, Charlotte, Series Editor, Pearce, Lynne, Series Editor, and Bond, Emma

Published
2018
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48. Why do legislators keep failing victims in online harms?

Author

Phippen, Andy and Bond, Emma

Subjects
*COMPUTER crimes, *COMPUTER crime laws, *DIGITAL technology, *CRIME victims
Abstract

Online harms policy debates, and subsequent legislation, take, as their starting point, a prohibitive perspective which assumes that harms that occur online can be prevented, and, because they are facilitated with digital technology, they can be prevented with such. By exploring current debates around the pinnacle of online harms legislation in the UK, the Online Safety Bill, we propose that this prohibitive mindset, along with a failure to appreciate online harms as a social ill, rather than a technical one, will emerged poorly developed without a victim centric focus. In exploring the development of legislation around the non-consensual sharing of intimate images, we illustrate the failures in victim centric policy development, and argue that there are many parallels with the 'war of drugs' and the failures to tackle these social problems with prohibitive legislation, and suggest there is much to learn from these issues should policy makers care to look. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Contributors

Author

Akintunde, Stephen, primary, Antunes, Maria Luz, additional, Atkinson, Jeremy, additional, Azeroual, Otmane, additional, Baker, David, additional, Bond, Emma, additional, Brenton, Sam, additional, Buck, Ellen, additional, Caplan, Victoria F., additional, Chan, Diana L.H., additional, Ellis, Lucy, additional, Fulkerson, Melissa, additional, Glimstedt, Amanda, additional, Hamilton, Martin, additional, Hawley, Graeme, additional, Henderson, Scott, additional, Johannsen, Carl Gustav, additional, Kirkham, Paul, additional, Kjellin, David, additional, Lopes, Carlos, additional, Machin-Mastromatteo, Juan D., additional, Maidment-Otlet, Richard, additional, Mann, Rosanna, additional, May, Rob, additional, Mears, Sarah, additional, Michnik, Katarina, additional, Moniarou-Papaconstantinou, Valentini, additional, Nunn, Anna, additional, Phippen, Andy, additional, Romo-González, José Refugio, additional, Rylance, Rick, additional, Sanches, Tatiana, additional, Schöpfel, Joachim, additional, Shackleton, Lucy, additional, Shen, Yi, additional, Smith, Daniella, additional, Szekely, Bulcsu, additional, Tarango, Javier, additional, Tury, Sandra, additional, Vassilakaki, Evgenia, additional, Wales, Tim, additional, Winters, Jane, additional, and Zain, Sayeda, additional

Published
2021
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