Diffuse gas in galaxies sheds new light on the origin of type Ia supernovae
Diffuse gas in galaxies sheds new light on the origin of type Ia supernovae
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DOI：
10.1093/mnras/stu907
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发表时间：
2014-01
影响因子：
4.8
通讯作者：
J. Johansson;T. Woods;M. Gilfanov;M. Sarzi;Yan-Mei Chen;K. Oh
中科院分区：
文献类型：
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作者：
J. Johansson;T. Woods;M. Gilfanov;M. Sarzi;Yan-Mei Chen;K. Oh
我们测量了被动演化（“退休”）星系中HeII $\lambda$ 4686星云发射的强度，旨在限制它们在Ia型超新星（SNe Ia）单简并（SD）情景下的热吸积白矮星（WDs）数量。在SD情景中，当WD燃烧从伴星吸积的富氢物质时，它成为电离紫外线发射的强大来源。如果星系中存在大量这样的源，那么HeII的重组线中的强发射应该是来自星际介质的。为了探索这一猜想，我们从斯隆数字巡天（Sloan Digital Sky Survey）中选择了11500个恒星年龄为bbbb1gyr的发射线星系，这些星系没有AGN活动的迹象，并将它们的光谱加到恒星群年龄的桶中。我们首次在退休星系中探测到HeII $\lambda$ 4686星云的辐射，发现它明显弱于SD情景的预期，特别是在最年轻的年龄区（1-4 Gyr），那里的SN Ia率最高。相反，观测到的HeII $\lambda$ 4686星云发射的强度与渐近后巨大分支恒星是所有年龄区唯一的电离源是一致的。这些结果将光球温度（$T_{\rm eff}$）在（1.5-6）$\cdot 10^5$ K范围内的吸积WDs的数量限制在不超过5-10的水平% of the observed SN Ia rate. Conversely, should all WD progenitors of SN Ia go through the phase of steady nuclear burning with $T_{\rm eff}$~(1.5-6)$\cdot 10^5$ K, they do not increase their mass by more than ~0.03 $M_\odot$ in this regime.
We measure the strength of HeII$\lambda$4686 nebular emission in passively evolving ("retired") galaxies, aiming to constrain their populations of hot accreting white dwarfs (WDs) in the context of the single degenerate (SD) scenario of Type Ia supernovae (SNe Ia). In the SD scenario, as a WD burns hydrogen-rich material accreted from a companion star, it becomes a powerful source of ionizing UV emission. If significant populations of such sources exist in galaxies, strong emission in the recombination lines of HeII should be expected from the interstellar medium. To explore this conjecture, we select from the Sloan Digital Sky Survey ~11 500 emission line galaxies with stellar ages >1 Gyr showing no signs of AGN activity and co-add their spectra in bins of stellar population age. For the first time, we detect HeII$\lambda$4686 nebular emission in retired galaxies and find it to be significantly weaker than that expected in the SD scenario, especially in the youngest age bin (1-4 Gyr) where the SN Ia rate is the highest. Instead, the strength of the observed HeII$\lambda$4686 nebular emission is consistent with post-asymptotic giant branch stars being the sole ionizing source in all age bins. These results limit populations of accreting WDs with photospheric temperatures ($T_{\rm eff}$) in the range ~(1.5-6)$\cdot 10^5$ K to the level at which they can account for no more than ~5-10% of the observed SN Ia rate. Conversely, should all WD progenitors of SN Ia go through the phase of steady nuclear burning with $T_{\rm eff}$~(1.5-6)$\cdot 10^5$ K, they do not increase their mass by more than ~0.03 $M_\odot$ in this regime.