SLIDE 1
Polarimetry as a Window into Supernova Explosions and Progenitors
Jennifer L. Hoffman University of Denver @astroprofhoff
SN 1994D
SLIDE 2 (Linear) polarization results from asphericity, so…
- It yields insight into collapse/explosion mechanisms.
- It tells us about the stellar winds and circumstellar material
- f progenitor stars.
- It helps us probe stellar evolution in
faraway galaxies.
- It has potential implications for
the use of some supernovae as cosmological probes.
SN 2008aq
Why do we care about supernova polarization?
SLIDE 3
All types of supernovae can be polarized!
< 10 M
SLIDE 4
Leonard+ 2007
Very hot ejecta ⇒ electron scattering is the polarizing mechanism.
SLIDE 5
SN 2004dj (II-P)
A polarized SN continuum indicates aspherical ejecta.
Leonard+ 2006
SLIDE 6
Polarization in spectral lines probes distribution of elements in the ejecta and surroundings.
SN 2001el (Ia) Kasen+ 2003
SLIDE 7
Rel. Flux Pol. (%) PA (º) Wavelength (Å) Hα
Next frontier in SN studies : time-domain spectropolarimetry!
Hoffman+ 2008 SN 1997eg (IIn)
SLIDE 8
SN 1997eg (IIn) Hoffman+ 2008
Next frontier in SN studies : time-domain spectropolarimetry!
SLIDE 9
SN 1997eg (IIn) Hoffman+ 2008
Next frontier in SN studies : time-domain spectropolarimetry!
SLIDE 10
SN 1997eg (IIn) Hoffman+ 2008
Next frontier in SN studies : time-domain spectropolarimetry!
SLIDE 11
SN 1997eg (IIn) Hoffman+ 2008
Next frontier in SN studies : time-domain spectropolarimetry! With this technique, we can probe pre-existing CSM and infer progenitor properties.
SLIDE 12
6.5-m MMT, Mt. Hopkins 2.3-m Bok, Kitt Peak 61” Kuiper, Mt. Bigelow
The SNSPOL project (led by U. Arizona) is creating the largest database of supernova polarization evolution to date.
DU grad student Leah Huk @MMT
SLIDE 13
50+ SNe of all types observed so far, most at multiple epochs.
Ia SN 2011 fe (16) SN 2012cg (11) SN 2012ht (3) SN 2013fw (1) SN 2014ao (4) SN 2014J (7) Ib SN 2012 au (19) iPTF13bvn (3) Ic PTF12gzk (5) SN 2012ej (8) SN 2012fh (16) SN 2013ff (7) SN 2013ge (8) SN 2014as (2) SN 2014ad (7) SN 2014L (10) II SN 2011bv (2) SN 2013am (12) SN 2013bu (9) SN 2013ee (5) SN 2013hj (3) IIb SN 2011dh (4) SN 2012fg (12) SN 2013ak (5) SN 2013df (4) ASASSN-14az (5) II-P SN 2012A (22) SN 2012aw (24) SN 2012ch (2) SH 2012ec (20) SH 2012ho (1) SN 2013ab (12) SN 2013bi (11) SN 2013ej (11) SN 2013fs (9) SN 2014A (3) SN 2014bc (1) IIn SN 2009ip (12) SN 2010jl (30) SN 2011cc (1) SN 2011ht (7) PTF11iqb (1) SN 2012ab (2) SN 2014ab (17) II-L SN 2014G (8)
SLIDE 14
2012a Vabs=-14.5 2012b Vabs=-18
Mauerhan+ 2013
SN 2009ip: Multiple maxima over several years suggest pre-explosion LBV eruptions. What caused the two 2012 peaks?
2012a Vabs=-14.5 2012b Vabs=-18
SLIDE 15
The two 2012 maxima showed orthogonal polarization angles, implying they were not due to successive shell ejections.
Mauerhan+ 2014
High %P at 2012b is typical of CSM interaction.
SN 2009ip, V band
SLIDE 16
Mauerhan+ 2014
The picture from spectropolarimetry: ejecta asphericity plus interaction with pre-existing equatorial CSM.
Torus geometry is often seen around LBVs, B[e] supergiants, etc.
SLIDE 17
- Modeling: individual objects, object classes,
time evolution
- Better statistics: more objects, greater
wavelength and time coverage
- Classification: illuminate relationships
among subtypes
SN 2004dj
- Late stellar evolution: draw connections
with potential progenitors What’s next for polarized supernovae?
- GMT polarimetry not ruled out, but needs
community push! (Want to help?)
SLIDE 18
0.0 0.5 1.0 1.5
Pol (%)
90 100 110
Position Angle (deg)
O III Bowen H I N III Bowen N II
1.8 1.0 0.2
Intensity (arb units) Wavelength (Ang)
3000 3500 4000 4500 5000 5500 6000 6500
What’s next for polarized supernovae?
Robert Stobie Spectrograph (RSS) at SALT (11-m): Polarimetry commissioning will start in 2015. ← T Pyx 2011 nova outburst, R ~ 800.
Nordsieck 2012
SLIDE 19 Polarimetry as a Window into Supernova Explosions and Progenitors
Jennifer L. Hoffman University of Denver @astroprofhoff
SN 1994D
SNSPOL:
Chris Bilinski (Steward Obs) Luc Dessart (U. de Nice) Douglas C. Leonard (SDSU) Jon Mauerhan (UC Berkeley) Peter A. Milne (Steward Obs) Nathan Smith (Steward Obs.) Paul S. Smith (Steward Obs.) NSF AST-1210599 RSS: Kenneth H. Nordsieck (U. Wisconsin) Marsha Wolf (U. Wisconsin) Jeff W. Percival (U. Wisconsin) Kurt P. Jaehnig (U. Wisconsin) Michael P. Smith (U. Wisconsin)
