# Evaluating Optical Classification for {\em Fermi} Blazar Candidates with a Statistical method using Broadband Spectral Indices

## TL;DR

This study uses broadband spectral indices to statistically classify uncertain Fermi blazar candidates as BL Lac objects or FSRQs, demonstrating good agreement with spectroscopic identifications and highlighting selection effects.

## Contribution

The paper introduces a statistical method based on broadband spectral indices for classifying Fermi blazar candidates, validated against spectroscopic data.

## Key findings

- 34% of radio-selected BCUs are BL Lac-like
- 77.3% of X-ray selected BCUs are BL Lac-like
- High consistency with optical spectroscopic classifications

## Abstract

We aim to test if a blazar candidate of uncertain-type (BCU) in the third Fermi active galactic nuclei catalog (3LAC) can be potentially classified as a BL Lac object or a flat spectrum radio quasar (FSRQ) by performing a statistical analysis of its broadband spectral properties. We find that 34% of the radio-selected BCUs (583 BCUs) are BL Lac-like and 20% of them are FSRQ-like, which maybe within 90% level of confidence. Similarly, 77.3% of the X-ray selected BCUs (176 BCUs) are evaluated as BL Lac-like and 6.8% of them may be FSRQ-like sources. And 88.7% of the BL Lac-like BCUs that have synchrotron peak frequencies available are high synchrotron peaked BL Lacs in the X-ray selected BCUs. The percentages are accordingly 62% and 7.3% in the sample of 124 optical-selected BCUs. The high ratio of source numbers of the BL Lac-like to the FSRQ-like BCUs in the X-ray and optically selected BCU samples is due to the selection effect. Examining the consistency between our evaluation and spectroscopic identification case by case with a sample of 78 radio-selected BCUs, it is found that the statistical analysis and its resulting classifications agree with the results of the optical follow-up spectroscopic observations. Our observation campaign for high-|\rho_{s}| BCUs , i.e., |\rho_{s}|>0.8, selected with our method is ongoing.

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Source: https://tomesphere.com/paper/1702.08604