Seoul National University - Eric Y....

Improving Type Ia supernova cosmologyEric Y. Hsiao Florida State University

on behalf of the Carnegie Supernova Project and collaborationsM. M. Phillips, C. Contreras, N. Morrell, C. R. Burns, M. Stritzinger,G. H. Marion, D. J. Sand, P. Hoeflich, T. Diamond et al.

Eric Y. Hsiao [email protected] EAMA Seoul, September, 2016

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Type Ia supernova cosmology Calibration of supernova luminosity is achieved through empirical relations.

Credit: Mark Phillips

mailto:[email protected]

Eric Y. Hsiao [email protected] FSU, October 20153

■ Type Ia supernova cosmology is currently systematic limited.■ On their origins, “they are explosions of C/O white dwarfs in binary systems”

is about the only thing we can agree on.



How to improve improve Type Ia supernova cosmology?

Go to the near infrared!

Outline1. Why near infrared?2. Probing the physics.

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Why near infrared? Theory and observation agree they are better standard candles in the NIR.

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Theory Observation

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Why near infrared? Observations in the NIR suffer little dust extinction.

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Why near infrared? There is mounting evidence for its utility in the NIR.

■ Krisciunas et al. 2004Dispersion in near infrared < 0.2 mag.

■ Wood-Vasey et al. 2008Dispersion of 0.16 mag in H.

■ Folatelli et al. 2010Dispersion of 0.18 mag in J.

■ Mandel et al. 2011Near infrared provide independent information.

■ Kattner et al. 2012Slight near-infrared decline rate relation detected.

■ Barone-Nugent et al. 201212 supernovae in the Hubble flow show dispersion < 0.010 in H.

■ Weyant et al. 2014Can achieve low dispersion with 1-3 light-curve points.

■ Friedman et al. 2015Near-infrared light curves of 92 nearby supernovae.

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1985ApJ...296..379E

Elias et al. (1985)



Why near infrared? CSP II aims to produce the definitive low-redshift reference with emphasis in NIR.

Carnegie Supernova Project II (CSP II) PI: Mark Phillips

■ Well-understood and stable photometric system.

■ Allocated in 2011-2015:800 nights on 1-m Swope for optical light curves 300 nights on 2.5-m du Pont for NIR light curves 70 nights on 6.5-m Magellan for NIR spectroscopy

■ Observations completed in 2011-2015:NIR light curves of 123 Type Ia supernovae in the Hubble flow. 624 NIR spectra of 151 Type Ia supernovae.

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Credit: Yuri Beletsky



Why near infrared? NIR is also the ideal region to probe the physics of supernovae.

Improve Type Ia supernovae cosmology through 2 routes:

■ Avoid things we do not understand.

■ Probe the physics.

We do not know the nature of the explosion and the companion star.

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Credit: ESO

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Why near infrared? NIR provides independent information unavailable in the optical.

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Hsiao et al. in prep

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Probing the physics NIR spectra contain many physical diagnostics.

■ Unburned material Pre-maximum C I 1.0693

■ Boundary between C/O burningPre-maximum Mg II 1.0927

■ Mass and distribution of radioactive nickelPost-maximum H-band break

■ Stable nickel Transitional phase [Ni II]

■ Companion signaturePost-maximum hydrogen P-beta

■ Progenitor central density and magnetic field,explosion (a)symmetryNebular phase [Fe II] 1.6440

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Probing the physics Carbon represents pristine material from the progenitor white dwarf.

■ Detection of carbon indicates incomplete burning and provides constraints for explosion models.

■ Optical surveys detected C II 6580in 20-30% of supernovae.Thomas et al. (2011) Folatelli et al. (2012)Silverman et al. (2012)

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Thomas et al. (2011)



Probing the physics Carbon appears to be ubiquitous, contrary to findings in the optical.

■ Near-infrared C I 1.0693 is always stronger and lasts longer than its optical counterpart.

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Hsiao et al. (2013, 2015)

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Probing the physics So far, no stripped hydrogen from companion has been detected.

■ Hydrogen stripped off the companion star is embedded at low velocity.

■ NIR P-beta is stronger and appear above photosphere earlierthan optical H-alpha (Maeda et al. 2014).

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Sand, Hsiao et al. (2016)



How to improve improve Type Ia supernova cosmology?

Go to the near infrared!

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Conclusion


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