Dirty Fireballs and Orphan Afterglows: A Broader Landscape of Stellar Death

As presented at the GROWTH meeting in Milwaukee, Oct 2017

Transcript

1. Dirty Fireballs and Orphan Afterglows: Anna Ho, Caltech with S. Kulkarni (Caltech), D. Perley (LJMU), V. Ravi (Caltech), N. Kawai (Tokyo Tech), B. Cenko (UMD/ Goddard), and G. Cunningham (UMD) A Broader Landscape of Stellar Death ah@astro.caltech.edu
2. Afterglow afterglow prompt emission an w init ⇡ 100 ! -rays ✓jet ISM CSM init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? Classical long gamma ray bursts (GRBs): the exemplar engine-driven relativistic explosion image credit: Brittany Miller
3. Afterglow afterglow prompt emission an w init ⇡ 100 ! -rays ✓jet ISM CSM init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? Initial Lorentz factor could be between SNe and GRBs image credit: Brittany Miller
4. Afterglow afterglow prompt emission an w init ⇡ 100 ! -rays ✓jet ISM CSM init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? Off-axis observer sees jet as it broadens afterglow prompt emission orphan afterglow init ⇡ 100 ! -rays ISM CS init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? image credit: Brittany Miller
5. Afterglow afterglow prompt emission an w init ⇡ 100 ! -rays ✓jet ISM CSM init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? afterglow prompt emission orphan afterglow init ⇡ 100 ! -rays ISM CS init ⇡ 100: classical GRB init ⇡ 5: dirty fireball init ⇡ 5 ! X-rays? image credit: Brittany Miller GRBs may simply be one manifestation of a broader landscape of relativistic explosions that includes dirty fireballs and orphan afterglows. Off-axis observer sees jet as it broadens
6. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation)
7. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) Rapidly-fading afterglows w/o GRB trigger: iPTF14yb, ATLAS17aeu, PTF11agg Cenko et al. (2013) 1 day 2 hrs 10 days 100 days 1000 days Flux Density (µJy) 0.1 1 10 100 1000 PTF11agg
8. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) ZTF high-cadence survey (3x/night) well-matched to dirty fireballs.
9. Primary false positive: M-dwarf flares Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation)
10. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) FOV 160º x 3º 160º x 3º Image credit NASA adapted from Mihara et al. (2011) All-sky, 2-20 keV, localization 3 deg2 MAXI: Monitor of All-sky X-ray Image
11. MAXI: Monitor of All-sky X-ray Image All-sky, 2-20 keV, localization 3 deg2 Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) FOV 160º x 3º 160º x 3º Image credit NASA adapted from Sugizaki et al. (2011) Gas proportional counter +1.5º Slit -1.5º +40º -40º adapted from Mihara et al. (2011)
12. MAXI-only burst ~once every two months Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) Only MAXI MAXI + other Fig. from online MAXI database
13. “MAXI-only” events relatively soft and low-luminosity Fig. reproduced from Serino et al. (2014) Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation)
14. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation)
15. VLA follow up for two soft MAXI-only bursts (primary false positive: AGN) MAXI J0050+247 Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) VLA 2 GHz (S-band)
16. Observational predictions for dirty fireballs: rapidly-fading optical afterglow (ZTF), prompt X-Ray emission (MAXI), long-lived radio emission (confirmation) MAXI J0050+247: superflare from M-dwarf? • 0.02 deg-2 (Mooley et al. 2016) • Flare luminosity 6.25 x 1031 erg/s = 1000x quiescent luminosity • Quiescent X-ray / bolometric luminosity: 10-3 • Quiescent X-ray and radio luminosities obey Guedel-Benz relations
17. Observational predictions for orphan afterglows: rising and falling optical light curve (ZTF), long-lived radio emission (confirmation) log(time) log(flux density) Off-axis observer Post break universal light curve On-axis observer Hours Days Figure from Piran (2004)
18. Plans for ZTF: short-cadence search, filter, panchromatic rapid response Dirty Fireballs Wide search Orphan Afterglows High-Cadence Survey (1600 deg2, 3x/night) Ideally a nightly survey Filter Shape of light curve Host Spectral index from multi-band imaging (P60, LCO) Spectrum from SEDM Filter Gemini, Keck, DBSP Confirm extragalactic Detect emission at other wavelengths Swift/XRT, VLA
19. ZTF discovery 2nd detection 3rd detection if (1) rapidly fading and (2) hostless or near faint galaxy if r < 19 mag Imaging if spectrum is featureless Spectrum if spectral index -0.7 < α < -1 if (1) rapidly fading and (2) near faint galaxy iPTF14yb light curve Decision pathway for triggering Swift Hours Since Explosion r-band mag 4th detection Kafka alert issued Swift/XRT Swift/XRT