Searching High-z Supernovae with HSC and WFMOS Yutaka Ihara (U. Tokyo/IOA) Mamoru Doi, Naoki Yasuda, Tomoki Morokuma, Kohki Konishi, Kouich Tokita Subaru User’s Meeting 2009/01/14-16 @ Mitaka

Abstract We will search Type Ia supernovae with HSC and WFMOS. HSC (Imaging observations) Detect variable objects in high-z galaxies (5-10 nights (epochs) observations give SN light curves. ) →~1000 SNe Ia will be obtained for one year (two terms) survey. (2) WFMOS ・ ~500 spectra of SNe Ia will be obtained for one year. ・ ~1000 spectra of host galaxies of the detected SNe Ia Our Goal (1) For SN Ia properties ① SN rate study → Progenitor of SNe Ia ② SN Ia spectra → Diversity (2) For Cosmology ・Resolve the time variation of “Dark Energy” ・Obtain more accurate cosmological parameters (ΩM, ΩΛ, w)

Classification of SNe × × ○ ○ ○ Binary (WD) Ia Si line Core Collapse Ib × He line H line Ic × ○ Line shape IIn Narrow Plateau IIP Light curve Linear IIL

How to detect SNe ? (1) Detect variable objects with repeat imaging observations Example of a SN Ia at z=0.606 (Morokuma+2008) Reference Another Image Subtracted Image (2) Classify SNe ① From Spectra (Confirmed method) ② From Light Curves (with Uncertainty) II Ia Filippenko 1997

Why do SNe Ia are important? 　　　　　　　　　↓ Standard candle in the universe ・ Constant Maximum brightness ・ Uniform Light curves and spectra Very bright (MV~-19.3 mag) ・ Observable at cosmological distances (z~1.5) SN1994D © NASA / HST Measure the expansion of the universe using SNe Ia. On the contrary… Large systematic errors still exist on the cosmological parameter fit. Diversity of SNe Ia caused by Progenitors?, Metallicity of Host Galaxies?, Time evolution? or… → Need more spectra of SNe Ia from low-z to high-z

SN Ia survey Mid-z survey High-z survey ・ SNLS (0.2<z<0.9) ~700 SNe Ia obtained in 2003-07. Imaging: CFHT 4m ・ SDSS-II SN survey (0.1<z<0.4) ~500 SNe Ia obtained in 2005-07. Imaging: SDSS 2.5m ・ ESSENCE (0.2<z<0.9) ~200 SNe Ia obtained in 2002-07. Imaging: CTIO 4m High-z survey ・ SCP (0.3<z<1.4) ~30 SNe Ia obtained in 2002 and 2005,6. Imaging: Subaru 8m and HST ・ High-z Team (0.2<z<1.6) ~30 SNe Ia obtained in 2002-04 Imaging: HST HSC+WFMOS If using HSC (imaging) + WFMOS (spectroscopy), We will get ~1000 SNe Ia for one year survey. Out of them, ~500 SNe Ia are high-z SNe (z>1.0).

Science with SNe Ia

SN Ia rate study → Many SNe Ia samples are very useful. Motivation SN Ia rate is the clue of progenitors of SNe Ia Recently, large delay time distribution of SNe Ia are shown by rate studies. ( “Delay time” → time interval between star formation and SN explosion ) ★ Two populations of SNe Ia ? (Mannucci+2005, 2006) Sullivan+06 Nearby results (e.g. Cappellaro+99) “Prompt” : Short delay time (~0.1-1Gyr) “Tardy” : Long delay time (~1-10Gyr) High-z rate is important!! It is difficult to measure that from current SN surveys → HSC+WFMOS survey Neill+06 (SNLS work) Prompt Tardy

Results of our work and the others ( Detailed results will be shown in Joint Subaru/Gemini Science Conference) At highest-z (z>1.4), very large errors due to small statistics Ihara+09 (SXDS) Dahlen+08 (GOODS) Poznanski+07 (SDF) Neill+06 (73) (SNLS) z=0.47 Dilday+08 (17) (SDSS) z=0.12 Ihara+09 shows increasing rates toward z~1.2

Expecting Results ? ? If a major fraction of SNe Ia is “prompt”, SN Ia rates increase toward z~2 (SFR peak), else SN Ia rates decrease. HSC+WFMOS resolve SN Ia population!! ? ?

Diversity of SNe Though SNe Ia should have uniformed property, diversities of colors, light curves, or spectra are found by large surveys. → These diversities affect measuring cosmological parameters. Ex.1) Color-Color diagram of mid-z SNe Ia Ex.2) Diversity of Light curves -0.8 -0.4 0.0 0.4 -0.2 0.0 0.2 0.4 0.6 U-B B-V Conley et al. 2008 Kim et al.

Diversity of SNe Corrected diversities with stretch factor, epoch, and MW extinction → But the diversities still remain… → Extinction of host galaxies? Metallicity of hosts? Other unknown reasons? → Resolve that by large statistic samples of SN Ia spectra ( Need large amounts of SNe at each epoch and stretch factor) Red　sample Blue sample Tokita 2009 PhD thesis

Diversity of SNe Correlation of EW(FeII) and Color of SNe Ia (?) (see detail on Konishi’s Poster) → SN spectra may be useful to decide color terms of SNe SALT2 (Light curve fitting method) (Guy+2007) Color term A few spectra of SNe… Large statistical samples with WFMOS will find distinct correlations. ● Subaru(SDSS) ● Suspect At max Konishi+09 in prep

Cosmology Small statistics at z>1 Need more samples Kowalski’s work → Using all SNe Ia obtained by SN surveys or the other works → 307 SNe Ia (after selection cuts) Small statistics at z>1 Need more samples Enough statistics Errors depend on systematic

Cosmology ★ Need spectroscopic information Using WFMOS, Redshift should be determined well below 1% level Difficult only with photometric information ★ Need spectroscopic information Combine with photo-z of host galaxies? Different error properties are expected Spectroscopy of host galaxies Need large observing time Using WFMOS, Get ~50 SNe Ia spectra at once!! And, get spectra of their host galaxies at the same time.

Cosmology ○ Errors on ΩM and w ○ The time variation of Dark Energy reduce by a factor of 2 ○ The time variation of Dark Energy will be constrained Kowalski et al. 2008 HSC+WFMOS Contour : 1σ

Summary WFMOS → Spectra of ~500 SNe Ia and HSC → Detect ~1000 SNe Ia at z<1.5 WFMOS → Spectra of ~500 SNe Ia and all of the ~1000 host galaxies This survey will be the largest and the deepest SN survey for the next five years. ① Nature of SNe Ia and their evolution can be explored with large sample. → SN Ia rate study ( for progenitors) → Diversities ② Measure cosmological parameters → ΩM, ΩΛ, w → The time variation of Dark Energy (?)

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