Observational aspects of Cosmological Transient Objects Poonam Chandra Royal Military College of Canada

Outline Supernovae and Gamma Ray Bursts – Introduction Supernovae : Physics from multiwaveband observations Ongoing and Future projects Gamma Ray Bursts – afterglows Multiwaveband modeling of afterglows Importance of radio observations Future of GRB afterglows in view of ALMA and EVLA

Supernovae and Gamma Ray Bursts: Stellar deaths

8M Θ ≤ M ≤ 30M Θ Supernova M ≥ 30M Θ Gamma Ray Burst

Supernovae

Circumstellar interaction in supernovae CS wind Explosion center Reverse Shock Forward Shock Ejecta

Trace back the history of the progenitor star since wind velocity ~10 km/s and ejecta speeds ~10,000 km/s. Supernova observed one year after explosion gives information about the progenitor star 1000 years before explosion!!! Forward Shock Reverse Shock CS wind

X-ray and Radio emission Information about the mass loss rate of the star, density of the shocked ejecta, temperatures, density of the CSM Radio X-ray

Radio absorption process. Synchrotron self absorption (SSA): magnetic field, size of the shell. Free-free absorption (FFA): Mass loss rate of the progenitor star. FFA SSA

More fundamental properties, such as microphysics of acceleration of electron, equipartition energy density distribution. Radio

GMRT VLA Synchrotron cooling break at 4 GHz Frequency FluxmJyFluxmJy Synchrotron cooling break at ~ 5.5 GHz GMRT VLA Frequency FluxmJyFluxmJy SN 1993J Chandra et al. 2004a, 2004b On day 3200 B=330 mG On day 3770 B=280 mG

SN 2010jl: Chandra Observations Chandra et al. 2012a Dec 2010 Oct 2011 Column density=3E+23 cm-2 Column density=1E+24 cm-2 Temperature 80 KeV Speed 7000 km/s External X-ray absorption

Suggested by Schlegel Unusual optical characteristics: – Very high bolometric and H  luminosities – H  emission, a narrow peak sitting atop of broad emission – Slow evolution and blue spectral continuum Late infrared excess Indicative of dense circumstellar medium. Very diverse in nature

Peak radio and X-ray luminosities

Multiwaveband Study Radio: circumstellar medium characteristics X-ray: Shock temperature, ejecta structure. Optical: Temporal evolution, chemical composition, explosion, distance IR: circumstellar dust nebula surrounding SN.

Multiwaveband campaign to understand Type IIn supernovae Observe all the Type IIN supernovae with the Very Large Array within 150 Mpc distance (PI: Chandra). If bright enough, do spectroscopy with XMM- Newton (PI: Chandra). Follow radio bright and/or Swift detected Type IIN supernova with ChandraXO. Get spectroscopy, separate from nearby contamination (PI: Chandra). If detected in radio, follow with Swift-XRT (PI: Soderberg). NIR photometry with PAIRITEL (PI: Soderberg). Observe all the Type IIN supernovae with the Very Large Array within 150 Mpc distance (PI: Chandra). If bright enough, do spectroscopy with XMM- Newton (PI: Chandra). Follow radio bright and/or Swift detected Type IIN supernova with ChandraXO. Get spectroscopy, separate from nearby contamination (PI: Chandra). If detected in radio, follow with Swift-XRT (PI: Soderberg). NIR photometry with PAIRITEL (PI: Soderberg). Chandra, Soderberg, Chevalier, Fransson, Chugai

VLA observations of Type IIn supernovae

Absorption Mechanism: SN 2006jd (Chandra et al. 2012b)

FLAT DENSITY PROFILE -1.45, Chandra et al. 2012b

X-ray light curves (Chandra et al. 2012b)

TWO SEPARATE KINDS OF TYPE IIN SUPERNOVAE!!!!

Gamma Ray Bursts

AG is synchrotron emission produced by electrons accelerated in a relativistic shock interacting with the circumburst medium. Entire temporal and spectral evolution is governed by simple physical parameters – Blast kinetic energy: E k – Circumburst density: n(r) – Shock microphysics: p, ε e, ε b

Long lived afterglow with powerlaw decays Spectrum broadly consistent with the synchrotron. Measure F m, m, a, c and obtain E k (Kinetic energy), n (density),  e,  b (micro parameters), theta (jet break), p (electron spectral index). GRB (Chandra et al. 2008) GRB (Chandra et al. 2010)

Radio Observations Late time follow up- accurate calorimetry Eg Frail et al. Scintillation- constraint on size (GRB ) VLBI- fireball expansion (GRB ) Density structure: wind-type versus constant

GRB : Scintillation (fireball >2 microarcsec) (Chandra et al. 2008)

Detectable at high redshifts in radio bands due to negative K-correction Effect was first noted by Ciardi & Loeb (2000) Steep synchrotron self-absorption ( ν 2 ) partially counteracts d L 2 diming Time dilation (1+z) helps to probe the early epoch of reverse shock From z=2 to z=10 flux density drops only 40% 28 Frail et al. (2006)

Reverse shock emission from GRB (Chandra et al. 2010) Reverse shock seen in GRB (z=6.26) too RS seen in PdBI data too on day 1.87

GRB (Chandra et al. 2010) Highest redshift GRB at z=8.2 Highest redshift object of any kind known in our Universe. Must have exploded just 630 million years after the Big Bang.

Last Chandra measurement

Swift Era: Missing Jets? Fewer than 10% of all Swift X-ray light curves show breaks consistent with a jet-like outflow. Koceveski & Butler (2008)

Swift Complications: Soft Energy Response keV BAT bandpass provides limited spectral coverage Often miss E peak Leads to large uncertainties in E γ,iso Abdo et al., 2009 GRB B Swift energy response

Swift Complications: Redshift 35 Median Swift redshift 2X higher. Shifts t jet to later times. From Palli Jakobssson webpage Complete to November 2009

Swift Complications: Energy Injection Bright flares and long- lived plateau phases in X-ray afterglows Can inject significant amount of energy into forward shock (Ek) Falcone et al. 2005

Inverse-Compton in X-rays: GRB (Chandra et al. 2008)

Detection rate in radio – 30% (Chandra et al. 2012, accepted in ApJ)

Post Swift detection rate– 30% (redshift independent) (Chandra et al )

(Chandra et al. 2012, accepted in ApJ)

Radio detectability of GRB afterglows Dependence on fluence Dependence on Isotropic Energy Dependence on X-ray flux Dependence on optical flux

(Chandra et al. 2012, accepted in ApJ)

Future of GRB Physics: A seismic shift in radio afterglow studies Expanded Very Large Array (EVLA) 20 times more sensitive than the VLA.

(Chandra et al. 2012, accepted in ApJ) SHB XRF SN-GRB LGRB

ALMA. What can we expect? Years of (painful) mm/submm work at BIMA, OVRO, PdBI, JCMT, IRAM 30-m, CSO and CARMA. A 30% detection rate. – Radio & optical selected sample – ~2.5 mJy at t=7-14 days (too late) 47

Future: Atacama Large Millimeter Array (ALMA) Accurate determination of kinetic energy

Future: ALMA Debate between wind versus ISM solved

Swift had expected to find many RS At most, 1:25 optical AG have RS Does not explain why prompt radio emission is seen more frequently. About 1:4 radio AG may be RS Possible Explanation: The RS spectral peak is shifted out of the optical band to lower frequencies 50 Kulkarni et al. (1999) Reverse shock in radio GRBs Chandra et al. (to be submitted)

Swift had expected to find many RS At most, 1:25 optical AG have RS Does not explain why prompt radio emission is seen more frequently. About 1:4 radio AG may be RS Possible Explanation: The RS spectral peak is shifted out of the optical band to lower frequencies 51 Kulkarni et al. (1999) Reverse shock in radio GRBs Chandra et al. (to be submitted)

mm emission from RS if observed few hours after the burst is bright, redshift-independent as effects of time-dilation compensates for frequency-redshift. (no extinction or scintillation). ALMA will be ideal with 75 uJy/4 min sensitivity. 52 Inoue, Omukai, Ciardi (2007) Reverse shock emission from high-z GRBs and implications for future observations Inoue, Omuka & Ciardi (2006).

Molecular and Atomic Absorption Lines Optical/NIR spectroscopy of bright GRB AGs has measured Z, T g, n and Δ V of high z SF ALMA (z>5) – HD 112 um (Pop III coolant) – [OI] 63.2 um (higher Z coolant) – [CII] 158 um (will replace CO) – H um (too hard?) ALMA (z=1-4) – CO lower transitions – HCN, HCO+, etc Eventually the AG goes away – Probe global galaxy properties – Image dust and line emission Inoue, Omuka & Ciardi (2006). 53

(Chandra et al. 2012, accepted in ApJ) Density Kinetic Energy Redshift

Collaborators Dale Frail Roger Chevalier Alak Ray Alicia Soderberg Shri Kulkarni Brad Cenko Claes Fransson Nikolai Chugai Edo Berger