tsinghua university supernova program xiaofeng wang physics department & thca tsinghua...

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.!