Tsinghua University Supernova Program Xiaofeng Wang Physics Department & THCA
Jan 16, 2016
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 millenniumSN 1006 (brightest)
SN 1604 (Kepler’s SN)SN 1572 (Tycho’s SN)
SN 1054 (Crab Nebula)
Visible during the day
Nearest ones can be seen with naked eyes: rare! 8 in 2000 years
Type Ia supernovae as standard candles
1. “PhillipsPhillips relationrelation”: A correction to SN Ia light-curves based on light-curve shape drastically improves the quality of the standard candle.
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20%20%
8%!8%!
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
2. SN colour: A correction to the SN luminosity based on the SN colour
Image credit from NASA
Type Ia Supernovae— Lighthouse of the Universe
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, 2005Needed 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
Phillips RelationDust Absorptions
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 0.01-0.1m 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
Changes in CSM Ionization due to variable SN radiation field
Patat et al. Science 07
CSM around a Normal SN Ia
50 km/s Ejected 50 days before explosion
SN 2006X
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
1. TNT monitoring of bright SNe(~150 SNe:100 SNe Ia)
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.
Zhang, T., Wang, X., et al. 2012, AJ
Type IIn: SN 2010jl
Type IIn: SN 2010jl
TNT 2.16m 2.4m
BATC Xuyi AST3
3. Transient Survey
Discovery of a Nova in images @NAOC 60/90 schmidt telescope
• Telescope: 1.04/1.20m Schmidt, f/1.8, 3.14Telescope: 1.04/1.20m Schmidt, f/1.8, 3.14oo FoV FoV• Location: 118.465Location: 118.465°°E, 32.737E, 32.737°°NN• Sea level: 219mSea level: 219m• Observable night: 194Observable night: 194• Best seeing: Best seeing: θ θ = 0.81= 0.81″″ • Sky Light: 20.78 Mag (V), 21.38 Mag (B)Sky Light: 20.78 Mag (V), 21.38 Mag (B)• Temperature:Temperature: 2020oo—— +40 +40oo
• Wind Velocity: <20 m/sWind Velocity: <20 m/s
Facility: PMO 1.2-m schmidt @Xuyi
• Excellent image quality • A very high quality CCD• Good seeing and sky background
Antarctic Survey Telescope
Antarctic Survey Telescope1) 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
23/4/21 Siding Spring Observatory, ANU 2.3 m
Collaboration with Brian Schmidt’s group
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
Cooks Branch
Phase-Space of various transients in the Universe
Science Goals
Key ProjectsKey Projects
Type Ia SNeType Ia SNe Dwarf novaeDwarf novae
Transients in nearby galaxiesTransients in nearby galaxies Core collapse SNeCore collapse SNe
RR LyraeRR Lyrae Solar system objectsSolar system objects
CVsCVs AGNAGN
AM CVnAM CVn BlazarsBlazars
Flare starsFlare stars Hostless transientsHostless transients
Thank you!Enjoy your stay in Tsinghua Univ.!