The spectral index study for Fermi blazars

Is there a blazar behind GLIMPSE-C01?

“…The resulting typical two-bump appearance seems consistent with a flat spectrum radio quasars (FSRQs), with a spectral index 𝛼 = 0.50 ± 0.01 for both synchrotron and Compton bumps. The use of the classification method based on broad-band effective spectral indices [23] reinforces the FSRQ hypothesis. Moreover, energetic considerations points in this direction, as gamma flux from our analysis is 𝐹 𝛾 = (1.97 ± 0.03) × 10 −10 erg cm −2 s −1 , while its luminosity may be assumed to be of the order of the mean luminosity of bright Fermi blazars, 𝑖.𝑒.1.38 × 10 47 erg s −1 [24].…”

A blazar candidate for the Fermi source 4FGL J1848.7–0129

“…Arsioli et al 2015;Ouyang et al 2021). At this distance the K-corrected X-ray luminosity, using a typical FSRQ spectral index 𝛼 = −0.78 (Ouyang et al 2021), is 6.8 × 10 42 erg s −1 for the narrow 2 -10 keV range, while for radio, with a flat spectral index, we get 4.9 × 10 43 erg s −1 . These values seem to be compatible with those of blazars (e.g.…”

“…The blazar FSRQ hypothesis may be tested if we try to apply a classification method based on broad-band effective spectral indices, defined as 𝛼 12 = − log( 𝑓 2 )−log( 𝑓 2 ) log(𝜈 2 )−log(𝜈 2 ) , where 𝑓 1 and 𝑓 2 are flux densities at 𝜈 1 and 𝜈 2 , respectively. Following the work of Ouyang et al (2021), three energy bands are considered (radio at 5 GHz, optical at 5100 Å, and X-ray at 1 keV) to calculate two effective spectral indices (𝛼 𝑟 𝑜 = 1.3 and 𝛼 𝑜𝑥 = 0.9), converting the observed data to those wavelengths by assuming power laws with canonical empirical effective spectral indices for radio, optical and X-rays (as, for instance, in Abdo et al 2010a). As in our case the optical data is only a limit, so will be the corresponding 𝛼 𝑟 𝑜 and 𝛼 𝑜𝑥 .…”

“…As in our case the optical data is only a limit, so will be the corresponding 𝛼 𝑟 𝑜 and 𝛼 𝑜𝑥 . In spite of that, the classification of the source according to the criteria in Ouyang et al (2021) is always a FSRQ.…”

“…Taking a Hubble constant of 𝐻 0 = 69.6 km s −1 Mpc −1 , and assuming a flat Universe with Ω 𝑣 𝑎𝑐 = 0.714, this luminosity distance is equivalent to a redshift 𝑧 0.43, which seems plausible (e.g. Arsioli et al 2015;Ouyang et al 2021). At this distance the K-corrected X-ray luminosity, using a typical FSRQ spectral index 𝛼 = −0.78 (Ouyang et al 2021), is 6.8 × 10 42 erg s −1 for the narrow 2 -10 keV range, while for radio, with a flat spectral index, we get 4.9 × 10 43 erg s −1 .…”