Teo Muñoz Darias, Marie Curie Fellow, University of Southampton

OPTICAL TRANSIENTS: counterparts of Radio Transients

1. OPTICAL TRANSIENTS counterparts of Radio Transients Teo Muñoz Darias Marie Curie Fellow University of Southampton 4-PI-SKY Together with Adam Stewart Wednesday, June 13, 12
2. Motivation Optical/Infrared counterparts can provide key inputs to identify the nature of the radio transient • Radio/optical spectral slopes • Optical/Infrared colors (slopes) It is going to be difficult to follow up ALL the transients • Optical identification can be useful to discriminate. Wednesday, June 13, 12
3. Optical Astronomy Optical magnitudes • Logarithmic scale (as the human eye) • M = -2.5 Log (Flux) + Constant (the bigger the fainter) • Several bands (UBVRI / u’g’r’i’z’) Orders of magnitude (300 seconds exposure) • V ~ 26 ( 0.2 µJy ) 10 m Telescopes (Keck / GTC / SALT) • V ~ 24 ( 1 µJy ) 4m telescopes (WHT) • V ~ 23 ( 2 µJy ) 2m telescopes (Liverpool Telescope) • V ~ 6 ( 15 Jy ) Human eye 3 x 108 -- 109 GHz 300 nm -- 1µm Wednesday, June 13, 12
4. Rates for optical transients The Deep Lens Survey (DLS) 1.1 deg-2 days; 1000s time scales • Rate ~ 6.5 events deg-2 day-1 (18.6<B<23.8) Becker et al. 2004 • Three detections in B but Zero detections en R band (very blue) • M dwarf stars Kulkarni & Rau 2006 • 106 events per year 6000 in a 10 deg2 survey MPG/ESO survey 0.24 deg-2 days Rau et al. 2004 • Rate ~ 10-15 events deg-2 day-1 (3sigma <28; 16<R<23) • R band: 1 M dwarf; 2 CV/dwarf nova; Maybe one extragalactic Wednesday, June 13, 12
5. Usual suspects Supernovae • SN can be detected in radio at Z=0.01-0.1 • Well defined time scales (weeks - years) . • Associated with host galaxies AGNs: • They can be strong radio sources (~Jy) • R~23 we should reach Z~2 ( Z=5 requires V~26) CVs (e.g. dwarf Novae) • Much brighter in the optical • Spectroscopy Wednesday, June 13, 12
6. X-ray binaries • Bright optical sources outside the galactic plane. • Well know X-rays/optical/IR/radio correlations GRBs • 2 per day (all sky) • Day-week time scales (mJy radio sources ) e.g. Chandra et al. 2007 • R=23.6 mean magnitude of host galaxies Ovaldsen et al. 2007 Active stars Usual suspects Wednesday, June 13, 12
7. X-ray binaries • Bright optical sources outside the galactic plane. • Well know X-rays/optical/IR/radio correlations GRBs • 2 per day (all sky) • Day-week time scales (mJy radio sources ) e.g. Chandra et al. 2007 • R=23.6 mean magnitude of host galaxies Ovaldsen et al. 2007 Active stars Güdel et al. 2002 Usual suspects Wednesday, June 13, 12
8. RADIO/OPTICAL IDENTIFICATION Diagrams using Optical/IR/Radio fluxes and colours • The simpler the better • Quick identification of the nature of the transients: follow up? • Future population studies Radio (few GHz), optical (V/R bands) of a number of populations ★ Super Novae, GRBs ★ AGNs, X-ray binaries, different flavours of pulsars ★ Active stars ( Thanks to Manuel Güdel) CURRENT STATUS Wednesday, June 13, 12
9. Optical Vs Radio OPTICAL (mJy) RADIO (mJy) Wednesday, June 13, 12
10. Optical Vs Radio OPTICAL (mJy) RADIO (mJy) Wednesday, June 13, 12
11. Optical Vs Radio OPTICAL (mJy) RADIO (mJy) Wednesday, June 13, 12
12. “Independent” of distance RADIO/OPTICAL OPTICAL COLOUR Wednesday, June 13, 12
13. Summary and Future • MANY interesting TRANSIENTS are coming • We are investigating OPTICAL/RADIO ratios for several populations • Still some important caveats (biases, reddening...) • SOME IDEAS... • Optical colors • Infrared data Wednesday, June 13, 12