RECON

A method for measuring spectral power and reconstructing time series in active galactic nuclei

reference: Yan-Rong Li & Jian-Min Wang, 2018, MNRAS Letter 476, 55, NASA ADS Link

Compiling

To compile RECON, the following third-party packages are required:

MPICH, an MPI implementation (version 1.0 or higher), available at http://www-unix.mcs.anl.gov/mpi/mpich/
FFTW, a fast Fourier transform library (version 3.0 or higher), available at http://www.fftw.org/
GSL, the GNU Scientific Library (version 2.2.1 or higher), available at http://www.gnu.org/software/gsl
DNest, the diffusive nested sampling library, developed by Yan-Rong Li, which is a C version of the DNest code by Brendon Brewer (https://github.com/eggplantbren/DNest3), available at https://github.com/LiyrAstroph/DNest_C

After installing the above packages, edit the corresponding library paths in Makefile, and then use make to compile the RECON.

Running

mpiexec -n np ./recon param

where np is the number of cores and param is the parameter file.

Command-line Options

RECON provides several command-line options:

-g, generate a mock light curve using the PSD specified in param file, e.g.,

mpiexec -n 4 ./recon param -g

-s, set a seed for random number generator, e.g., set a seed with a value of 100,

mpiexec -n 4 ./recon param -s100

-l, implement level-dependent sampling, which usually improves sampling efficiency, e.g.,

mpiexec -n 4 ./recon param -l

-p, only do posterior processing when MCMC sampling is available, e.g.,

mpiexec -n 4 ./recon param -p

-t, set a temperature for posterior processing, e.g.,

mpiexec -n 4 ./recon param -t2

-d, calculate the periodogram (PSD) of input data, e.g.,

mpiexec -n 4 ./recon param -d

Once can also combine the above options, e.g.,

mpiexec -n 4 ./recon param -ls100

mpiexec -n 4 ./recon param -pt2

Parameter File

A typical parameter file looks like,

# parameter file
# lines beginning with '#' are regarded as comments and are neglected
#

PSDType    0                # psd type

#===============================================
# data

FileDir         .                # file direcotry

FileName        data/ngc5548.txt     # file name

V               2.0              # factor for extension of time interval in term of data
W               2.0              # factor for time resolution in terms of data  

FreqLimit       5.0e-4           # frequency limit below which PSD flattens off
FlagEndMatch    0                # end matching to reduce leakage
#===============================================
# only for simulation (-g option turned on)

FileSim         data/sim.txt       #
ND_Sim          200                # number of points
DT              1.0                # time resolution
FBad            0.33                # fraction of bad points
FErr            0.1                # measurement noise

# PSD argument
PSDArg          1.0e-3:2.5:0.0                # type 0, single power-law:  A:alpha:noise
#PSDArg          1.0e3:1.0e-2:0.0            # type 1, DRW: A:fknee:noise                         
#PSDArg           1.0e1:2.5:1.5:1.5e-2:0.01   # type 2, bending power-law: A:a1:a2:freq:noise
#===============================================

Outputs

RECON generates posterior samples posterior_sample.txt for PSD parameters and frequency series for reconstructing input time series. The reconstructions based on posterior samples are stored in recon.txt.

RECON also calculates evidence at the end of running, printed out on terminal screen.

MCMC Sampling

RECON employs diffusive nested sampling technique (DNest; Brewer et al. 2011, Stat. Comput. 21, 649) to generate MCMC sample. The configuration for DNest is specified in file OPTIONS.

An Exemplary Case

Application to the 5100A light curve of NGC 5548, see Yan-Rong Li & Jian-Min Wang, 2018, MNRAS Letter 476, 55.

A more detailed usage guideline is coming.

LiyrAstroph/RECON