ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Jun Okumura (Kyoto U)
Title: The Type~Ia supernovae rate with Subaru/XMM-Newton Deep Survey
Date (JST): Thu, Mar 27, 2014, 13:30 - 15:00
Place: Seminar Room A
Abstract: Though type Ia supernovae (SNe Ia) are remarkable objects as cosmological distance indicators, their progenitors are yet to be conclusively identified. There are two widely discussed scenarios for the progenitor, the single degenerate (SD) scenario and the double degenerate (DD) scenario. In the SD scenario, a C+O white dwarf accretes gas from a companion star in a binary system. Its mass increases up to the Chandrasekhar limit where it explodes as an SN~Ia. In the other hand, in the DD scenario, a merger of two C+O white dwarfs leads to an SN~Ia explosion.
To investigate this problem, ``delay time'', which is the time between binary system formation and subsequent SN explosion, is one of the promising signature for understanding the progenitor scenario of SNe Ia. Many studies have derived the SN~Ia delay time distribution (DTD) from observations.
In this context, high-redshift SN Ia rates (z>1) play an important role in investigating the DTD, especially for the short delay time regime, especially for the short delay time regime. We present measurements of the rates of high-redshift Type Ia supernovae derived from the Subaru/XMM-Newton Deep Survey (SXDS). We carried out repeat deep imaging observations with Suprime-Cam on the Subaru Telescope, and detected 1040 variable objects over 0.918 deg^2 in the Subaru/XMM-Newton Deep Field. From the imaging observations, light curves in the observed i'-band are constructed for all objects, and we fit the observed light curves with template light curves. Out of the 1040 variable objects detected by the SXDS, 39 objects over the redshift range 0.2 < z < 1.4 are classified as Type Ia supernovae using the light curves. These are among the most distant SN~Ia rate measurements to date. We find that the Type Ia supernova rate increase up to z~0.8 and may then flatten at higher redshift.