Swift-BAT

Swift-BAT is a repository containing the analysis pipeline for searching and placing fluence limits on associated $\gamma$-ray emission from CHIME/FRBs.

If the corresponding SWIFT/BAT data does not exist locally, the pipeline will automatically download it. (Key flag argument).

The pipeline uses a boxcar search convolution over user-set time scales and energy bands around a user-set search window (centered on the CHIME trigger time). To search for FRBs.

To produce fluence limits. The analysis pipeline produces a noise image, and a background subtracted count image for the search window. It then using the KBN method in astropy to determine a countlimit at 95%. It generates a SWIFT/BAT RSP file, and fits using XSPEC.

For more information see the SWIFT_CHIME_report.pdf in the repo.

Outputs

The pipeline produces two main outputs a diagnostic plot for each target, and a outcatalog json. Examples are in the main directory:

Diagnostic plot

A diagnostic plot containing 5-6 figures per target, including:

• A signal-to-noise ratio (SNR) lightcurve
• A zoomed-in SNR lightcurve for the search window
• A peak SNR vs time scale plot
• A sky image (if one is produced)
• A histogram of the photon energy for the data
• A histogram of the photon energy for the search window

Outcatalog JSON file

An outcatalog.json file containing the results of the analysis.

Requirements

Swift-BAT requires the following Python packages:

• NumPy
• Matplotlib
• Astropy
• Re
• swifttools
• subprocess
• tqdm
• xspec

In addition, Swift-BAT requires the following software package:

• HEASoft

Getting Started

To use Swift-BAT, you can clone the repository and run the pipeline on your local machine. Before running the pipeline, make sure you have installed the required Python and software packages listed above.

To run the pipeline, simply execute the swift-bat.py script with the appropriate command-line arguments. The incatalog is expected as a .csv file formatted as "swift_id, trig_time, chime,id, ra , dec". With the ra, dec in degrees, and the trig_time being the CHIME trigger time.

Acknowledgments

This pipeline was developed by Maxwell A. Fine as part of AST425 (Undergraduate Thesis Class) at the University of Toronto. I was co-supervised by Ziggy Pleunis and Paul Scholz, as well as Professor Bryan Gaensler. Aaron Tohuvavohu was instrumental in understanding HEASoft and working with BAT data.

Known Bugs/Issues

• SWIFT API sometimes bugs out, this is protected for the downloading data but not for converting into MET/ SWIFT time
• pipeline does not work for all cases, known failures:
  • wrong type of bat .evt file
  • multiple SWIFT dumps using the same ID
  • some issue in the boxcar search for targets
  • failure to generate .RSP file or taret is out of frame of the sky image

Next Steps

• investigate and correct pipeline failures
• triple check that the events should be the background subtracted events from the sky image, and background is the noise image for the KBN method. (As opposed to using non-background subtracted events for the events in the sky image).
• add argparse arguments for XSPEC settings, and confidence level for KBN method
• Try Source Stacking

Contact

If you have any questions or feedback, please contact Maxwell Fine:

• Website: https://afinemax.github.io/afinemax1/
• GitHub: https://github.com/afinemax
• Email: [email protected]