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Subject: ELFT HÍRADÓ
[Fizinfo] MTA CSFK CSI RENDKÍVÜLI SZEMINÁRIUM, 2013. 12. 10. (kedd) 14:00
- From: Uhlár Karola <uhlar AT konkoly.hu>
- To: szeminar AT konkoly.hu, fizinfo AT lists.kfki.hu
- Subject: [Fizinfo] MTA CSFK CSI RENDKÍVÜLI SZEMINÁRIUM, 2013. 12. 10. (kedd) 14:00
- Date: Fri, 06 Dec 2013 10:11:16 +0100
*MTA CSFK CSI RENDKÍVÜLI SZEMINÁRIUM*
Előadó:***Alejandro H. Córsico* (Universidad Nacional de La Plata, Argentina)
Előadás címe: *Constraining the axion mass through white dwarf asteroseismology*
Axions are (still conjectural) non-baryonic particles considered as candidates for dark matter of the Universe. Their contribution to the dark matter depends on their mass, a quantity that is not given by the theory that predicts their existence. At the typical temperatures and densities found in the cores of white dwarfs, it is expected that copious emission of axions through bremsstrahlung processes takes place at the deepest regions of these stars. The mass of the axions determines how strongly they couple with electrons and, then, how large the axion emissivity is. Since axions can (almost) freely escape from the interior of white dwarfs, their existence would increase the cooling rate, with more massive axions producing larger additional cooling. Pulsating white dwarfs with hydrogen-rich atmospheres, also known as DAV or ZZ Ceti stars, can be used as astrophysical laboratories to constrain the properties of fundamental particles like axions by comparing the measured rates of period changes of these stars with the expected values from theoretical models.
In this talk, I will review the use of DAV white dwarfs as a tool to constrain the mass of the axion, and compare the predictions from this method with the results obtained through other approach that employs the white dwarf luminosity function (WDLF). In particular, the mass of the axion derived from pulsating white dwarfs is more than 3 times larger than the limit derived from the WDLF method. While the origin of this discrepancy is still unknown, I will focus on the fact that, in order that the results derived from pulsating white dwarfs be robust, it is necessary that the modes considered in the analysis be modes trapped in the outer H envelope of the star. I enumerate a few possibilities connected with the modeling of the previous evolutionary history of DA white dwarfs that could lead to these modes be non-trapped.
Előadás időpontja: *2013. december 10. (kedd), 14:00**
Előadás helyszíne: MTA CSFK CSI Előadóterme
1121 Budapest, Konkoly T. M. út 15-17.
begin:vcard fn:Karola Uhlar n:Uhlar;Karola org:Konkoly Observatory adr:;;Konkoly Thege M. u. 13-17.;Budapest;;1121;Hungary email;internet:uhlar AT konkoly.hu title:secretary tel;work:+3613919322 tel;fax:+3612754668 version:2.1 end:vcard
- [Fizinfo] MTA CSFK CSI RENDKÍVÜLI SZEMINÁRIUM, 2013. 12. 10. (kedd) 14:00, Uhlár Karola, 12/06/2013
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