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Astron. Astrophys. 358, 841-844 (2000)

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2. Correlation

2.1. Data

Since blazars are known to be strongly variable in [FORMULA]-rays, we use both maximum and average [FORMULA]-ray fluxes from Hartman et al. (1999). For the maximum fluxes, we use only those with significance level [FORMULA]. For the averages, we use the flux for the sum of all EGRET observation (denoted P1234 in Hartman et al. 1999); for the cases in which P1234 has only an upper limit, half of the (2[FORMULA]) limit value was used. For the emission line information, we used the data listed in the paper by Cao & Jiang (1999) except for the marked items. The relevant data are listed in Table 1, where Column 1 gives the name of the source; Column 2, classification, FQ for flat spectrum radio quasar and BL for BL Lacertae object; Column 3, the redshift; Column. 4 and 5, the maximum and the average [FORMULA]-ray flux in units of [FORMULA] photon cm-2 s-1 (the points with a star are half the upper limit while those with a dagger show a [FORMULA]); Column 6, the [FORMULA]-ray photon spectral index (from Hartman et al. 1999); Column 7, the flux of the emission line [FORMULA] in units of erg cm-2 s-1; Column 8 and 9, the maximum and the average [FORMULA]-ray luminosities at 0.4 GeV in units of erg s-1; Column 10, the luminosity of emission line in units of erg s-1.


[TABLE]

Table 1. Observation data for [FORMULA]-ray loud blazars.
Notes:
Col. 1, Name; Col. 2, Classification, FQ for flat spectrum radio quasar and BL for BL Lacertae object; Col. 3, the redshift; Col. 4, the maximum [FORMULA]-ray flux in units of [FORMULA] photon cm-2 s-1; Col. 5, the average [FORMULA]-ray flux in units of [FORMULA] photon cm-2 s-1, Col. 6, the photon spectral index; Col. 7, the flux of the emission line in units of erg cm-2 s-1; Col. 8, the maximum [FORMULA]-ray luminosity at 0.4 GeV in units of erg s-1; Col. 9, the average [FORMULA]-ray luminosity at 0.4 GeV in units of erg s-1; Col. 10, the luminosity of emission line in units of erg s-1.
) Half value of the upper limit
[FORMULA]) 3.0 [FORMULA] 4.0
a) Scarpa & Falomo (1997) b) Morganti et al. (1992); c) Stockton & MacKenty (1987); d) Baker et al. (1994), Gondhalekar et al. (1986) e) Junkkarinen (1984); f) Vermeulen et al. (1995); g) Baldwin et al. (1989)


2.2. Result

The observed photons are converted to flux densities at E GeV as follows. Let

[EQUATION]

where [FORMULA] is the normalization and [FORMULA] is the photon spectral index given in Column 6. Integrating the above relation from 100 MeV to 10 GeV and setting it equal the observed photon flux given in Column 4 or 5, we obtain [FORMULA]. We calculate the flux density at 0.4 GeV, since that is about the average energy of the photons. The flux density is k-corrected according to [FORMULA], where [FORMULA] is the spectral index ([FORMULA] and [FORMULA]). Adopting H0 = 75 km s-1 Mpc-1 and q0 = 0.5, the distance at redshift z is [FORMULA] cm. Assuming an isotropic emission, then the luminosities can be calculated.

When the linear regression analysis is performed (excluding 3C 273) for the maximum [FORMULA]-luminosities, a correlation

[EQUATION]

is found, with a correlation coefficient [FORMULA] and a chance probability [FORMULA]. For the average [FORMULA]-luminosities, a correlation is (excluding 3C 273 again)

[EQUATION]

with a correlation coefficient [FORMULA] and a chance probability [FORMULA].

Fig. 1 shows the correlation for the average [FORMULA]-luminosities; open circles are for flat spectrum radio quasars while the filled points for BL Lacertae objects. The solid line is the best fit.

[FIGURE] Fig. 1. The [FORMULA]-ray luminosity vs. emission line luminosity using the average [FORMULA]-ray flux. The open circles are for flat spectrum radio quasars and the filled points for BL Lacertae objects

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© European Southern Observatory (ESO) 2000

Online publication: June 20, 2000
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