The Transient Sky

Eran Ofek CALTECH

Shri KulkarniArne RauMansi KasliwalBrian CameronAvishay Gal-YamDale Frail

Collaborators:

Talk LayoutTransients along the EM spectrum (review)

Motivation & the future

Ongoing optical searches

Individual transients (optical)

M85 OT 2006-1

SN2006gy

Kulkarni, Ofek et al. (2006 Nature submitted)Rau et al. (2006)Ofek et al. in prep

Ofek et al. (2006 ApJL submitted)

Transients along the EM (-rays)

Gamma rays

Long-GRBs

Short GRBs

Soft -ray repeaters

Massive stars

NS mergers?

Neutron Stars (NS)

?

Transients along the EM (-rays)Ofek et al. (2006 ApJ accepted)

Z=0.09

Progenitor age<10Myr

if NS merger:for kick velocity>35km/s

velocity

sizeregionage

Transients along the EM (~cm)

RadioSearching for radio transients

Levinson, Ofek et al. (2002)

Future: ATA SKA

Comparison of 2 radio surveys

Found: 2 genuine transients

Transients in nearby galaxies

Gal-Yam, Ofek et al. (2006)

Ofek et al. in prep

Transients along the EM (visible)

Many searches

But usually focused on specific classes…

Solar systemSupernovaeMicrolensing…

Motivation

New / rare kind of transients

Peculiar members of known families

Test models

Standard candle systematics

Summary of physical motivation

The future - LSST

8.4m mirror6.5m effective diameter

Field of view = 9.65 sq. deg

The future - LSST

LSST details

6 filters: ugrizY

~7000 sq. deg. per night

First light: 2013, Cerro Pachon

~1min transients alert

Single image: r~24 mag After 10yrs r~28 mag

Sky for everyone - No proprietary period!

Back to the present(Our) ongoing searches

Nearby clusters

Fornax, Perseus

SDSS-II

cadence improvingFollow up

Palomar 5mMPG 2.2mLCO 2.5m

Palomar robotic 60”

Palomar 48” (10 sq. deg)

Nearby galaxies surveyPalomar robotic 60”

Kulkarni, Ofek, Rau, Kasliwal

Another strategy…

Individual transients

M85 OT 2006-1

SN2006gy

Kulkarni, Ofek et al. (2006)Rau et al. (2006)Ofek et al. in prep

Ofek et al. (2006; ApJL submitted)

In the past year:

Follow-up of 6 transients

Examples:

M85 Optical Transient 2006-1Kulkarni, Ofek et al. (2006; Nature submitted)Rau et al. (2006; ApJL submitted)Ofek et al. in prep

M85 Optical Transient 2006-1

M85 Optical Transient 2006-1

Width~350km/s

M85 Optical Transient 2006-1Late time Spitzer observation

M85 Optical Transient 2006-1Late time Spitzer observation

M85 Optical Transient 2006-1

Green to red color evolution

60 day plateau

Peak abs. mag I~-13

Expansion velocity ~350 km/s

Cool black-body at late time

E~1047 erg (in 3 months)

a-spherical expansion?

M85 Optical Transient 2006-1

…like: M31-RV & V838 Mon

M85 Optical Transient 2006-1

…like: M31-RV & V838 Mon

Favored model:

Stellar merger(Soker & Tylenda)

M85 Optical Transient 2006-1

Searching for his brothers

SN 2006gy Ofek et al. (2006 ApJL submitted)

Discovered: 2006 Sep 18 (Quimby et al.)

H line

AGN(?) - Prieto et al. (2006)

Type-IIn supernova (SN) ? Harutyunyan et al.Foley et al. (2006)

However,early type galaxyAbs mag @ peak ~-22~50 days rise time

SN Nucleus

Dust lane

FWHM ~0.”1

SN 2006gy Ofek et al. (2006 ApJL submitted)

SN 2006gy Ofek et al. (2006 ApJL submitted)

SN 2006gy Ofek et al. (2006 ApJL submitted)

S0 template with EB-V=0.16 extinction

SN+galaxy @ day~45

SN+galaxy @ day~7

SN 2006gy Ofek et al. (2006 ApJL submitted)

SN 2006gy Ofek et al. (2006 ApJL submitted)

VLA – no detection

Swift/XRT – no detection

Chandra (PI: Pooly)

VariableX-ray source @ galaxy center

Hybrid IIn/Ia SN (Type-IIa)

SN 2002ic -20.1 ~20 late type galaxy

SN 2005gj -20.4 ~55 blue Irr. MB~-17

SN 1997cy -20.1 <30 blue LSB MB~-17.7

SN 1999E <-19.5 <140 MB~-15 spiral

SN 2006gy -22.2 ~50 S0 galaxy

NameAbs V-m

ag

Rise time [d]

Environment

SN 2006gy Ofek et al. (2006 ApJL submitted)

energy

Total radiated energy ~1.2x1051 erg during 2 months

Type-Ia SN features in spectra

Assuming SN2006gy is a type-Ia SN

kinetic energy of a Ia SN (~1-2x1051 erg)

radiation

SN 2006gy Ofek et al. (2006 ApJL submitted)

Assuming SN2006gy is a type-Ia SN

kinetic energy of a Ia SN (~1-2x1051 erg)

radiationRequires:

Mass-loss rate ~10-2 M /yr

Over ~100yr

Common envelope? (Livio & Riess 2003)

SN 2006gy Ofek et al. (2006 ApJL submitted)

Summary

First year – “listening” mode:

The “known”: 1 LBV(?), 2+1(?) dwarf novae

The “known unknown”:

Out of 6 targets:

The “unknown unknown”

M85 OT 2006-1

SN 2006gy

Still waiting…

End

Transients along the EM (-rays)Ofek (2006b); Ofek et al. (2006a)

Extragalactic SGRs

M85 Optical Transient 2006-1

M85 Optical Transient 2006-1Comparison with other types of transients

Transients along the EM (~cm)

VLA J172059+38

VLA J121550+13 in NGC 4216

SN 2006gy Ofek et al. (2006)

Peak absolute V-band magnitude ~-22.2

Summary

Total radiated energy ~1.2x1051 erg during 2 months

Type-Ia SN features in spectra

SDSS-15207

SDSS-15207

Chandra (PI: Pooley)

XRT – no detectionVLA – no detection

SN 2006gy Ofek et al. (2006 ApJL submitted)

M85 Optical Transient 2006-1

Searching for his brothersin nearby galaxies…