Nathaniel R. Butler

The long rapid decay phase of the extended emission from the short GRB 080503 (2009)

Genet, Franck, Butler, Nathaniel R., Granot, Jonathan

GRB080503 was classified as a short GRB with extended emission (Perley et al. 2009). The origin of such extended emission (found in about a quarter of Swift short GRBs) is still unclear and may...

The Cosmic Rate, Luminosity Function and Intrinsic Correlations of Long GRBs (2009)

Butler, Nathaniel R., Bloom, Joshua S., Poznanski, Dovi

We calculate durations and spectral parameters for 207 Swift bursts detected by the BAT instrument from April 2007 to August 2009, including 67 events with measured redshifts. This is the first...

Limits on Radioactive-Powered Emission Associated With a Short-Hard GRB 070724A in a Star-Forming Galaxy (2009)

Kocevski, Daniel, Thone, Christina C, Ramirez-Ruiz, Enrico, Bloom, Joshua S., Granot, Jonathan, Butler, Nathaniel R., ...

We present results of an extensive observing campaign of the short duration, hard spectrum gamma-ray burst (GRB) 070724A, aimed at detecting the radioactively-powered emission that might follow from...

GRB 090426: The Environment of a Rest-Frame 0.35-second Gamma-Ray Burst at Redshift z=2.609 (2009)

Levesque, Emily M., Bloom, Joshua S., Butler, Nathaniel R., Perley, Daniel A., Cenko, S. Bradley, Prochaska, J. Xavier, ...

We present the discovery of an absorption-line redshift of z = 2.609 for GRB 090426, establishing the first firm lower limit to a redshift for a gamma-ray burst with an observed duration of 90%...

Gamma-ray Bursts, Classified Physically (2008)

Bloom, Joshua S., Butler, Nathaniel R., Perley, Daniel A.

From Galactic binary sources, to extragalactic magnetized neutron stars, to long-duration GRBs without associated supernovae, the types of sources we now believe capable of producing bursts of...

Generalized Tests for Selection Effects in GRB High-Energy Correlations (2008)

Butler, Nathaniel R., Kocevski, Daniel, Bloom, Joshua S.

Several correlations among parameters derived from modelling the high-energy properties of GRBs have been reported. We show that well-known examples of these have common features indicative of strong...

A Complete Catalog of Swift GRB Spectra and Durations: Demise of a Physical Origin for Pre-Swift High-Energy Correlations (2007)

Butler, Nathaniel R., Kocevski, Daniel, Bloom, Joshua S., Curtis, Jason L.

We calculate durations and spectral paramaters for 218 Swift bursts detected by the BAT instrument between and including GRBs 041220 and 070509, including 77 events with measured redshifts....

X-ray Hardness Variations as an Internal/External Shock Diagnostic (2007)

Butler, Nathaniel R., Kocevski, Daniel

The early, highly time-variable X-ray emission immediately following GRBs exhibits strong spectral variations that are unlike the temporally smoother emission which dominates after $t\sim 10^3$ s....

Multicolor Infrared Observations of SN 2006aj, the Supernova Associated with XRF 060218 - Paper I (2006)

Kocevski, Daniel, Modjaz, Maryam, Bloom, Joshua S., Foley, Ryan, Starr, Daniel, Blake, Cullen H., ...

We report simultaneous multicolor near-infrared (NIR) observations of the supernova associated with x-ray Flash 060218 during the first 16 days after the high energy event. We find that the light...

X-ray Hardness Evolution in GRB Afterglows and Flares: Late Time GRB Activity Without N_H Variations (2006)

Butler, Nathaniel R., Kocevski, Daniel

We show that the X-ray and $\gamma$-ray spectra of Swift GRBs and their afterglows are consistent with the emission characteristic of an expanding, relativistic fireball. The classical afterglow due...

On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission (2006)

Butler, Nathaniel R.

We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus...

The X-ray Afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: Possible Evidence for a Supernova Prior to GRB 020813 (2003)

Butler, Nathaniel R., Marshall, Herman L., Ricker, George R., Vanderspek, Roland K., Ford, Peter G., Crew, Geoffrey B., ...

We report on the detection of an emission line near 1.3 keV, which we associate with blue-shifted hydrogen-like sulfur (S XVI), in a 76.8 ksec Chandra HETGS spectrum of the afterglow of GRB 020813....