ICCF-Cut

ICCF-Cut, proposed by Ma et al. 2023, is a tool designed for broadband PRM. It extracts the emission line lightcurve with two broadband lightcurves.

ICCF-Cut simply needs two broadband lightcurves:

• a line band which contains the broad emission line Halpha;
• a continuum band which is adjacent to the line band and nearly contains no emission line components.

In addition, ICCF-Cut needs the ratio of the broad emission line in the line band, i.e. the flux of the broad emission line divided by the total flux of the line band. This can be determined from a single-epoch spectrum of the AGN.

Then, you can try:

$ python iccfcut.py [continuum band filename] [line band filename] [ratio]

to extract the Halpha lightcurve. Each input lightcurve file should contain 3 columns: MJD, FLux and Flux error. The output lightcurve file for the emission line is Halpha.txt.

Please note that there is a variable gap that needs to be set manually in iccfcut.py. It should be a list with:

• length equal to the observational seasons of the lightcurves;
• the i th value of gap should be larger than the last observation date of the i th season, but less than the first observation date of the i+1 th season.

We provide an example of Mrk 841 in the Example directory. To extract the Halpha lightcurve of Mrk 841, you can try:

$ python iccfcut.py Mrk841g.txt Mrk841r.txt 0.18

We provide the data of the final lightcurves used for the delay estimations of 23 AGNs in Ma et al. 2024 (submitted) in the lightcurves directory.

You are welcome to use and modify ICCF-Cut. If you do, please acknowledge its use with a citation to:

• Ma et al. 2023
• Ma et al. 2024 (ApJ accepted).