Direct observation of the cooling of the Cassiopeia A neutron star
Direct observation of the cooling of the Cassiopeia A neutron star
The cooling rate of young neutron stars (NSs) gives direct insight into their internal makeup. Although the temperatures of several young NSs have been measured, until now a young NS has never been observed to decrease in temperature over time. We fit nine years of archival Chandra ACIS spectra of the likely NS in the ~330 yr old Cassiopeia A supernova remnant with our non-magnetic carbon atmosphere model. Our fits show a relative decline in the surface temperature by 4% (5.4?, from (2.12 ± 0.01) × 106 K in 2000 to (2.04 ± 0.01) × 106 K in 2009) and the observed flux by 21%. Using a simple model for NS cooling, we show that this temperature decline could indicate that the NS became isothermal sometime between 1965 and 1980, and constrains some combinations of neutrino emission mechanisms and envelope compositions. However, the NS is likely to have become isothermal soon after formation, in which case the temperature history suggests episodes of additional heating or more rapid cooling. Observations over the next few years will allow us to test possible explanations for the temperature evolution
dense matter, neutrinos, pulsars, neutron, supernovae: individual, cassiopeia a, x-rays, stars
L167-L171
Heinke, Craig O.
d7382ed2-cb85-4e15-b2d9-296fc8b6221d
Ho, Wynn C. G.
d78d4c52-8f92-4846-876f-e04a8f803a45
20 August 2010
Heinke, Craig O.
d7382ed2-cb85-4e15-b2d9-296fc8b6221d
Ho, Wynn C. G.
d78d4c52-8f92-4846-876f-e04a8f803a45
Heinke, Craig O. and Ho, Wynn C. G.
(2010)
Direct observation of the cooling of the Cassiopeia A neutron star.
The Astrophysical Journal Letters, 719 (2), .
(doi:10.1088/2041-8205/719/2/L167).
Abstract
The cooling rate of young neutron stars (NSs) gives direct insight into their internal makeup. Although the temperatures of several young NSs have been measured, until now a young NS has never been observed to decrease in temperature over time. We fit nine years of archival Chandra ACIS spectra of the likely NS in the ~330 yr old Cassiopeia A supernova remnant with our non-magnetic carbon atmosphere model. Our fits show a relative decline in the surface temperature by 4% (5.4?, from (2.12 ± 0.01) × 106 K in 2000 to (2.04 ± 0.01) × 106 K in 2009) and the observed flux by 21%. Using a simple model for NS cooling, we show that this temperature decline could indicate that the NS became isothermal sometime between 1965 and 1980, and constrains some combinations of neutrino emission mechanisms and envelope compositions. However, the NS is likely to have become isothermal soon after formation, in which case the temperature history suggests episodes of additional heating or more rapid cooling. Observations over the next few years will allow us to test possible explanations for the temperature evolution
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Published date: 20 August 2010
Keywords:
dense matter, neutrinos, pulsars, neutron, supernovae: individual, cassiopeia a, x-rays, stars
Identifiers
Local EPrints ID: 173841
URI: http://eprints.soton.ac.uk/id/eprint/173841
ISSN: 2041-8205
PURE UUID: 5c767b01-8ba3-47da-9cf0-daedde9bdd05
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Date deposited: 09 Feb 2011 08:47
Last modified: 14 Mar 2024 02:31
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Author:
Craig O. Heinke
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