{"id":216,"date":"2015-11-10T12:00:42","date_gmt":"2015-11-10T11:00:42","guid":{"rendered":"http:\/\/markus-kromer.de\/wordpress\/?p=216"},"modified":"2016-05-05T20:42:14","modified_gmt":"2016-05-05T19:42:14","slug":"type-ia-supernovae-from-violent-mergers-of-carbon-oxygen-white-dwarfs-polarization-signatures","status":"publish","type":"post","link":"https:\/\/markus-kromer.de\/wordpress\/type-ia-supernovae-from-violent-mergers-of-carbon-oxygen-white-dwarfs-polarization-signatures\/","title":{"rendered":"Type Ia supernovae from violent mergers of carbon\u2013oxygen white dwarfs: polarization signatures"},"content":{"rendered":"<p>The violent merger of two carbon\u2013oxygen white dwarfs has been proposed as a viable progenitor for some Type Ia supernovae. However, it has been argued that the strong ejecta asymmetries produced by this model might be inconsistent with the low degree of polarization typically observed in Type Ia supernova explosions. In this paper, we test this claim by carrying out a spectropolarimetric analysis for the model proposed by Pakmor et\u00a0al. for an explosion triggered during the merger of a 1.1 and 0.9\u2009M<sub>\u2299<\/sub>\u00a0carbon\u2013oxygen white dwarf binary system.\u00a0Owing to the asymmetries of the ejecta, the polarization signal varies significantly with viewing angle. We find that polarization levels for observers in the equatorial plane are modest (\u22721\u00a0per\u00a0cent) and show clear evidence for a dominant axis, as a consequence of the ejecta symmetry about the orbital plane. In contrast, orientations out of the plane are associated with higher degrees of polarization and departures from a dominant axis.<\/p>\n<p><img loading=\"lazy\" class=\"aligncenter size-full wp-image-217\" src=\"http:\/\/markus-kromer.de\/wordpress\/wp-content\/uploads\/2016\/05\/merger_pol.png\" alt=\"merger_pol\" width=\"2070\" height=\"1030\" srcset=\"https:\/\/markus-kromer.de\/wordpress\/wp-content\/uploads\/2016\/05\/merger_pol.png 2070w, https:\/\/markus-kromer.de\/wordpress\/wp-content\/uploads\/2016\/05\/merger_pol-250x124.png 250w, https:\/\/markus-kromer.de\/wordpress\/wp-content\/uploads\/2016\/05\/merger_pol-1024x510.png 1024w, https:\/\/markus-kromer.de\/wordpress\/wp-content\/uploads\/2016\/05\/merger_pol-624x310.png 624w\" sizes=\"(max-width: 2070px) 100vw, 2070px\" \/>While the particular model studied here gives a good match to highly polarized events such as SN 2004dt, it has difficulties in reproducing the low polarization levels commonly observed in normal Type Ia supernovae. Specifically, we find that significant asymmetries in the element distribution result in a wealth of strong polarization features that are not observed in the majority of currently available spectropolarimetric data of Type Ia supernovae.<\/p>\n<p>Paper published in\u00a0<a href=\"http:\/\/dx.doi.org\/10.1093\/mnras\/stw962\">Monthly Notices of the Royal Astronomical Society<\/a>, full text available at\u00a0<a href=\"http:\/\/arxiv.org\/abs\/1510.04128\">http:\/\/arxiv.org\/abs\/1510.04128<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The violent merger of two carbon\u2013oxygen white dwarfs has been proposed as a viable progenitor for some Type Ia supernovae. However, it has been argued that the strong ejecta asymmetries produced by this model might be inconsistent with the low &hellip; <a href=\"https:\/\/markus-kromer.de\/wordpress\/type-ia-supernovae-from-violent-mergers-of-carbon-oxygen-white-dwarfs-polarization-signatures\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/posts\/216"}],"collection":[{"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/comments?post=216"}],"version-history":[{"count":3,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/posts\/216\/revisions"}],"predecessor-version":[{"id":220,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/posts\/216\/revisions\/220"}],"wp:attachment":[{"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/media?parent=216"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/categories?post=216"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/markus-kromer.de\/wordpress\/wp-json\/wp\/v2\/tags?post=216"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}