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Tsinghua University Supernova Program. Xiaofeng Wang Physics Department & THCA Tsinghua University. Supernova Classification and Explosion Mechanism. Thermonuclear Explosion. Core-Collapse Explosion.
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Tsinghua UniversitySupernova 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. “Phillipsrelation”: 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
TypeIa Supernovae— Lighthouse of the Universe Image credit from NASA
The Accelerating Universe Nobel Prize for Physics in 2011! Riess et al., 1998 Perlmutter et al., 1999
Challenges for Precise Cosmology with SNe Ia B. Schmidt, 2005 Needed mag ~ 0.01 !!!
Discovery of a Supernova (Automatic pipeline)
Systematic Errors in SN Ia distances Dust Absorptions Phillips Relation Tausenbeger etal. 2011
CSM Dust? Very blue echo spectrum; Dust with grain size between 0.01-0.1m is required (Wang et al. 2008b)
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 SNeIaEvolution of Na I D lines SN 2006X Changes in CSM Ionization due to variable SN radiationfield 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
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 Tsinghua Univ. Supernova Program
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.
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
2.4m 2.16m TNT 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 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
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
Thank you! Enjoy your stay in Tsinghua Univ.!