The Classification of Blazar Candidates of Uncertain Types

In this work, the support vector machine (SVM) method is adopted to separate BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs) in the plots of the photon spectrum index against the photon flux, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi></mrow></semantics></math></inline-formula>, those of the photon spectrum index against the variability index, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mi mathvariant="italic">V</mi><mspace width="-0.166667em"></mspace><mi mathvariant="italic">I</mi></mrow></semantics></math></inline-formula> and those of the variability index against the photon flux, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>log</mi><mspace width="0.166667em"></mspace><mrow><mi>V</mi><mspace width="-0.166667em"></mspace><mi>I</mi></mrow><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi></mrow></semantics></math></inline-formula>. Then, we used the dividing lines to distinguish BL Lacs from FSRQs in the blazar candidates of uncertain types from the <i>Fermi</i>/LAT catalogue. Our main conclusions are: 1. We separate BL Lacs and FSRQs by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>=</mo><mo>−</mo><mn>0.123</mn><mspace width="0.166667em"></mspace><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi><mo>+</mo><mn>1.170</mn></mrow></semantics></math></inline-formula> in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi></mrow></semantics></math></inline-formula> plot, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>=</mo><mo>−</mo><mn>0.161</mn><mspace width="0.166667em"></mspace><mi>log</mi><mspace width="0.166667em"></mspace><mrow><mi>V</mi><mspace width="-0.166667em"></mspace><mi>I</mi></mrow><mo>+</mo><mn>2.594</mn></mrow></semantics></math></inline-formula> in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>α</mi><mi>ph</mi></msub><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mrow><mi>V</mi><mspace width="-0.166667em"></mspace><mi>I</mi></mrow></mrow></semantics></math></inline-formula> plot and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>log</mi><mspace width="0.166667em"></mspace><mrow><mi>V</mi><mspace width="-0.166667em"></mspace><mi>I</mi></mrow><mo>=</mo><mn>0.792</mn><mspace width="0.166667em"></mspace><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi><mo>+</mo><mn>9.203</mn></mrow></semantics></math></inline-formula> in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>log</mi><mspace width="0.166667em"></mspace><mrow><mi>V</mi><mspace width="-0.166667em"></mspace><mi>I</mi></mrow><mo>∼</mo><mi>log</mi><mspace width="0.166667em"></mspace><mi>F</mi></mrow></semantics></math></inline-formula> plot. 2. We obtain 932 BL Lac candidates and possible BL Lac candidates, and 585 FSRQ candidates and possible FSRQ candidates. 3. Discussion is given regarding comparisons with the literature.