WFIRSTとすばる望遠鏡を使った
宇宙再電離期の超新星探査守屋 尭 (国立天文台)

Transient survey in WFIRST•

Main science driver: Type Ia SN cosmology• every 5 day for 2 years• 30 hours/visit (imaging + IFU spectra)• 2700 SNe Ia in total
Spergel et al. (2015)

layerarea(deg2)

filters

wide

27.44

Y, J

medium

8.96

J, H

deep

5.04

J, H

depth / targetedvisit
SN Ia
24.5
z < 0.4
mag
25.5
z < 0.8mag
26.5
z < 1.7magWhat WFIRST wants from ground telescopes•••

low-redshift SNe Ia (pre-survey)• 800 SNe Ia at z<0.1
photo-z for candidate selection
coordinated observations not required• IFU for spectroscopy• better to have them• color selection• LSST field?

Spergel et al. (2015)

Science with Subaru
Supernovae at the reionization era and beyond
with Subaru/HSC

Superluminous supernovae (SLSNe)•a new member of SN family• started to be discovered from ca. 2005
• bright and blue

Gal-Yam (2012)

How can SNe become superluminous?
•large production of 56Ni (more than 5 Msun)• pair-instability supernovae (PISNe)• explosions of stars between ~150 Msun and ~250 Msun
• only exist in metal-poor environment (Z < ~ Zsun/3)• first massive stars!
Hirano et al. (2014)

Langer (2012)

How can SNe become superluminous?
•interaction between SN ejecta and dense CSM• ~ 10 Msun CSM required• pulsational pair-instability• or other mechanisms

Yoshida et al. (2016)!efotfDTNTO
fkfdubti

pdl

Woosley et al. (2007)

How can SNe become superluminous?
•magnetars• rapidly-rotating strongly-magnetized neutron stars• huge rotational energy can be emitted with a timescale of ~ 10 days

What SLSNe tell us?
••

massive star population• SLSNe are from massive stars
massive stars preferentially formed at high-z?
• reionization• are there PISNe?
• synergy with GW astronomy
Prajs et al. (2016)

Marchant et al. (2016)

Cosmology with SLSNe•

possible relation between peak luminosity and decline rate• like in Type Ia SNe
Inserra & Smartt (2014)•Hubble diagram and constraint on the dark energy equation of state

Scovacricchi et al. (2016)

Current highest-redshift SLSN•

z = 3.9 (Cooke et al. 2012)• with CFHT/MegaCam• redshift from the host galaxy

z<6 with Subaru (optical)•HSC SSP can reach z~4• from this November• only two SLSN (candidates) at z>2 are currently known• first SNe at z>2 with spectroscopic confirmation
Prajs et al. (2016)z<6 with Subaru (optical)

Tanaka, Moriya, & Yoshida (2013)

NIR transient survey

WFIRST

Tanaka, Moriya, & Yoshida (2013)

How to confirm the SNe at the reionization era•
•spectral observations for all candidates are difficult• faint (~26 mag in NIR)
host galaxies are too faint - they will be “hostless”• no photo-z

How to confirm the SNe at the reionization era•••

if we have very deep z band from HSC at the same time
• high-z SNe will not be detected in z band
• high-z SNe will be detected as “z-drop” hostless SNe• observe the same field as the NIR survey to find “z-drop” SNe
27 mag in z band (~ 11 hours for S/N = 5)
• ~55 hours for 5 deg2 (deep field)• x a few epochs• hard for LSST?
Y band is too shallow

z>10: towards the first explosions

WFIRST

Tanaka, Moriya, & Yoshida (2013)

WFIRST•
•
•

•

Depth
• 26.5 magArea• 5 deg2Duration• 2 years• 50 days at z~6 = 1 yearTime• 2024 or later• JWST is from 2018
• for ~5+ years• TMT from 2028

WFIRSTSummary•supernovae with WFIRST• main goal is SN Ia cosmology• low-z SNe Ia from ground-based optical survey• photo-z• SLSNe at the reionization era will be discovered with Subaru• coordinated deep observations in z band
• look for “z-drop” SNe• ~ 100 - 200 hours/epoch in z band for several epochs• deep z band images will be obtained as well• difficult with LSST?
• long survey period of WFIRST is good for high-z SNe• can be coordinated with TMT (2028 -) and JWST (2018 - ?)• optical observations coordinated with space are interesting!