Tsinghua University Supernova Program Xiaofeng Wang Physics Department & THCA Tsinghua University

Supernova Classification and Explosion Mechanism Thermonuclear Explosion Core-Collapse Explosion

Galactic Supernovae in the past millennium SN 1006 (brightest) SN 1054 (Crab Nebula) Visible during the day SN 1572 (Tycho’s SN) SN 1604 (Kepler’s SN) Nearest ones can be seen with naked eyes: rare! 8 in 2000 years

Type Ia supernovae as standard candles 1. “Phillips relation”: A correction to SN Ia light-curves based on light-curve shape drastically improves the quality of the standard candle. 20% Brightness  2. SN colour: A correction to the SN luminosity based on the SN colour Many methods: Stretch – Perlmutter 97, 99 (M)LCS(2k2) – Riess, 95,96, Jha 07 SALT(2) – Guy 05, 07 ΔC12 – Wang X. 05 CMAGIC – Wang L. 03; Conley 06 Δm15 – Phillips 93; Hamuy 95; Prieto 06 Brightness  8%! Time 

Type Ia Supernovae— Lighthouse of the Universe Ia型超新星像标准烛光一样可以用来测宇宙学距离，这就好比同等亮度的蜡烛，放地越远看起来就越暗（出自NASA）。 Image credit from NASA

The Accelerating Universe  Nobel Prize for Physics in 2011! 在地球上抛一个苹果上去，其上升的速度不可能越来越大，但在宇宙尺度上，确实是这样的现象。 Riess et al., 1998 Perlmutter et al., 1999

Challenges for Precise Cosmology with SNe Ia B. Schmidt, 2005 Needed mag ~ 0.01 !!!

Debate on SNe Ia Progenitor System

Systematic uncertainties in SN Ia distances

Discovery of a Supernova (Automatic pipeline)

Systematic Errors in SN Ia distances Dust Absorptions Phillips Relation Tausenbeger etal. 2011

Circumstellar Dust？ （Wang X F, et al. ApJ, 2008a, 675, 626)

CSM Dust? Very blue echo spectrum; Dust with grain size between 0.01-0.1m is required (Wang et al. 2008b)

Spectroscopic Diversity of SNe Ia (Benetti et al. 2005; Branch et al Spectroscopic Diversity of SNe Ia (Benetti et al. 2005; Branch et al. 2006; Wang et al. 2009) (Wang et al. 2009)

Two SN Ia populations? Wang et al. 2009

Other common features in HV SNeIa Evolution of Na I D lines SN 2006X Changes in CSM Ionization due to variable SN radiation field CSM around a Normal SN Ia 50 km/s Ejected 50 days before explosion Patat et al. Science 07

Similar variable Na I D in SNe 1999cl and 2007le Blondin et al. 2009 Simon et al. 2007, 2009

Outflow from Na ID Sternberg et al. 2011, science

Outflow from Na ID Sternberg et al. 2011, science

HVG SNe Ia are reported to have systematically positive (redshifted) emission line shift in the nebular phase, while the LVG usually have negative shift (Maeda et al. 2010). This discrepancy was argued to be geometric effect for HVG and LVG SNe Ia. Maeda et al. 2010

Geometric effect? Maeda et al. 2010,nature

PTF11kly/SN 2011fe in M101 Nugent et al. 2011, nature

Constraints on progenitor of SN 2011fe Nugent et al. 2011, nature

HST archive image of the site of sn2011fe Li et al. 2011, nature

Tsinghua Univ. Supernova Program Collaborators: NAOC: Tianmeng Zhang, Zhou Xu, Jingsong Deng, Chao Wu, Lingzhi Wang PMO: Haibin Zhao, Xueguang Zhang CCAA: Lifan Wang, Zhaohui Shang BNU: Fang Huang, Zhen Liu

1. TNT monitoring of bright SNe (~150 SNe:100 SNe Ia)

2. Spectroscopic Identification and follow up at NAOC 2. 16-m & YNAO 2 2. Spectroscopic Identification and follow up at NAOC 2.16-m & YNAO 2.4-m telescopes In 2011: 12 nights on NAOC 2.16-m telescope (OMR+BFOSC) In 2012:7 nights on NAOC 2.16, 10 nights on YNAO 2.4 In 2013, ~30 nights (22 + 8 ToO) on NAOC 2.16, ~15 nights on YNAO 2.4 At present: ~200 spectra have been obtained for 60 SNe. Next year: ~200 spectra will be expected.

Early Spectra of SN 2011fe Wang et al. 2012a, in prep.

SYNOW Fit to t = -16 d Spectrum of SN 2011fe

HV vs. LV (Early Spectra) Wang et al. 2012a, in prep.

Type IIn: SN 2010jl Zhang, T., Wang, X., Wu, C., et al. 2012.

Type IIn: SN 2010jl Zhang, T., Wang, X., et al. 2012, AJ

Type IIn: SN 2010jl

2.4m TNT 2.16m 3. Transient Survey Xuyi AST3 BATC

Discovery of a Nova in images @NAOC 60/90 schmidt telescope

Facility: PMO 1.2-m schmidt @Xuyi Telescope: 1.04/1.20m Schmidt, f/1.8, 3.14o FoV Location: 118.465°E, 32.737°N Sea level: 219m Observable night: 194 Best seeing: θ = 0.81″ Sky Light: 20.78 Mag (V), 21.38 Mag (B) Temperature: -20o— +40o Wind Velocity: <20 m/s Excellent image quality A very high quality CCD Good seeing and sky background

Antarctic Survey Telescope

Antarctic Survey Telescope 1) Adjustable tower height (preliminary designed to be about 1.5m); 2) Foldable dome; 3) Active snow removing; 4) Auto-focusing.

Spectral identification of AST3 transients from telescopes in Australia Collaboration with Brian Schmidt’s group Siding Spring Observatory, ANU 2.3 m 2017/4/24

AST3 CCD Camera No shutter To be operated in Frame Transfer mode，10k x 5k FOV: ～4.3 sq. degree 16 readout channels

Observing Facilities For our Transient Survey BATC (0.6-m schmidt), Xuyi (1.05m), AST3(0.5m)  discovering SNe TNT, Skymapper  photometry NAOC 2.16m, YNAO 2.4m, ANU 2.3m, SNIFS?  identification, spectroscopic follow up

Phase-Space of various transients in the Universe Cooks Branch

Science Goals Key Projects Type Ia SNe Dwarf novae Transients in nearby galaxies Core collapse SNe RR Lyrae Solar system objects CVs AGN AM CVn Blazars Flare stars Hostless transients

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