cosmic rays and gamma ray bursts (grb’s)

Cosmic rays and Gamma Ray Bursts (GRB’s)

Prepared by Brant Carlson, Morris Cohen, and Benjamin CottsStanford University, Stanford, CA

IHY Workshop on Advancing VLF through the Global AWESOME Network

Gamma Rays and the Ionosphere

Solar ionization disappears at night Recombination rates on the order of ms Nighttime density maintained by cosmic ray flux

Gamma-ray bursts

Associated with very energetic explosions Collapsing star

Supernova formation

Typically lasts a few ms to several minutes

Accidentally discovered by Vela-3 spacecraft in 1967

Gamma-ray waveform

Broad variety of durations and shapes

Gamma-ray burst on the ionosphere

From Fishman et al. 1988

Massive gamma-ray burst

From Inan et al. 2007

Second timescale characteristics

From Inan et al. 2007

-25 dB disturbance!!

From Inan et al. 2007

Minutes timescale characteristic

From Inan et al. 1988

Slow recovery

Hour timescale characteristic

From Inan et al. 2007

Recovery lasts for over 1 hour!

ELF emissions generated

From Inan et al. 2007

Mechanism for ELF emissions in question….

GRBs/SGRs and VLF sensing

VLF remote sensing of D-region ionosphere

GRBs repeatedly disturb ionosphere

NLK: 16-hour observationsLargest disturbances

NLK: most spectacular cases

SGR-Illuminated hemisphere

January 22nd, 2009, 6:48 UT Calculated using http://home.att.net/~srschmitt/script_celestial2horizon.html

Sunrise position

0250 UT

0650 UT

1050 UT