First Direct Measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Mg</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>22</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>α</mml:mi><mml:mo>,</mml:mo><mml:mi>p</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mrow><mml:mi>Al</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>25</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> and Implications for X-Ray Burst Model-Observation Comparisons
J.S. Randhawa, Y. Ayyad, W. Mittig, Z. Meisel, T. Ahn, Sérgio Luiz Cruz Aguilar, H. Álvarez-Pol, D. W. Bardayan, D. Bazin, S. Beceiro-Novo, D. Blankstein, Liz P. Carpenter, M. Cortesi, D. Cortina‐Gil, P. Gastis, M. R. Hall, S. L. Henderson, J. J. Kolata, T. Mijatović, F. Ndayisabye, Patrick J. O’Malley, J. Pereira, AGUEMON Dourodjayé Pierre, H Robert, C. Santamaria, H. Schatz, J. K. Smith, N. Watwood, J. C. Zamora
Abstract
Type-I x-ray bursts can reveal the properties of an accreting neutron star system when compared with astrophysics model calculations. However, model results are sensitive to a handful of uncertain nuclear reaction rates, such as ^{22}Mg(α,p). We report the first direct measurement of ^{22}Mg(α,p), performed with the Active Target Time Projection Chamber. The corresponding astrophysical reaction rate is orders of magnitude larger than determined from a previous indirect measurement in a broad temperature range. Our new measurement suggests a less-compact neutron star in the source GS1826-24.