# 2010A&A...516A..59C

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 Query : 2010A&A...516A..59C

2010A&A...516A..59C - Astronomy and Astrophysics, volume 516, A59-59 (2010/6-2)

Is BL Lacertae an orphan'' AGN? Multiband and spectroscopic constraints on the parent population.

CAPETTI A., RAITERI C.M. and BUTTIGLIONE S.

Abstract (from CDS):

We have analysed optical spectra of BL Lacertae, the prototype of its blazar subclass, to verify the broad Hα emission line detected more than a decade ago and its possible flux variation. We used the spectroscopic information to investigate the question of the BL Lacertae parent population. Low- and high-resolution optical spectra of BL Lacertae were acquired with the DOLORES spectrograph at the 3.58m telescopio nazionale Galileo (TNG) during four nights in 2007-2008, when the source was in a relatively faint state. In three cases we were able to fit the complex Hα spectral range with multiple line components and to measure both the broad Hα and several narrow emission line fluxes. A critical comparison with previous results suggests that the broad Hα flux has increased by about 50% in ten years. This might be due to an addition of gas in the broad line region (BLR), or to a strengthening of the disc luminosity, but such flux changes are not unusual in Broad Lined active nuclei. We estimated the BL Lacertae black hole mass by means of its relation with the bulge luminosity, finding 4-6x108M. The virial mass estimated from the spectroscopic data gives instead a value 20-30 times lower. An analysis of the disc and BLR properties in different AGNs suggests that this discrepancy is due to an underluminosity of the BL Lacertae BLR. Finally, we addressed the problem of the BL Lacertae parent population, comparing its isotropic quantities with those of other AGN classes. From the point of view of the narrow emission line spectrum, the source is located close to low-excitation radio galaxies. When one also considers its diffuse radio power, an association with FR I radio galaxies is severely questioned due to the lower radio luminosity (at a given line luminosity) of BL Lacertae. The narrow line and radio luminosities of BL Lacertae instead match those of a sample of miniature radio galaxies, which however do not show a BLR. Yet, if existing, misaligned BL Lacertae'' objects should have entered that sample. We also rule out the possibility that they were excluded because of a QSO optical appearance. The observational constraints suggest that BL Lacertae is caught in a short term transient stage, which does not leave a detectable evolutionary trace'' in the AGN population. We present a scenario that can account for the observed properties.

Journal keyword(s): galaxies: active - BL Lacertae objects: general - BL Lacertae objects: individual: BL Lacertae - galaxies: jets

Full paper

 Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 ESO 113-45 Sy1 01 23 45.7631533440 -58 48 20.808928944   14.08 13.83 13.34   ~ 835 0
2 QSO B0235+1624 BLL 02 38 38.93010450 +16 36 59.2745528   16.46 15.50 15.92   ~ 1476 2
3 3C 84 Sy2 03 19 48.1599902040 +41 30 42.108850836   13.10 12.48 11.09   ~ 3857 3
4 Mrk 1506 Sy1 04 33 11.0956735296 +05 21 15.619461552   15.72 15.05 10.08   ~ 1947 2
5 Mrk 1095 Sy1 05 16 11.4092471904 -00 08 59.157166920   14.30 13.92     ~ 848 1
6 Ton 951 Sy1 08 47 42.4485615096 +34 45 04.482515304   14.83 14.50     ~ 451 0
7 NAME OKM2018 SWIFT J1224.1+4073 Sy1 12 23 58.9755962928 +40 44 09.288088260   16.97 16.76     ~ 30 0
8 M 84 Sy2 12 25 03.74333 +12 53 13.1393 12.67 12.09 10.49     ~ 1715 2
9 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5637 1
10 Mrk 771 Sy1 12 32 03.6223710000 +20 09 29.495834136   15.57 15.30     ~ 472 0
11 M 58 SyG 12 37 43.597 +11 49 05.12 10.80 10.48 9.66     ~ 1036 2
12 3C 279 Bla 12 56 11.16657958 -05 47 21.5251510   18.01 17.75 15.87   ~ 2922 2
13 QSO J1512-0906 Bla 15 12 50.53293048 -09 05 59.8297908   16.74 16.54     ~ 1255 1
14 3C 345 QSO 16 42 58.80997043 +39 48 36.9939552   16.81 16.59 16.84   ~ 1653 2
15 3C 371 BLL 18 06 50.6802916920 +69 49 28.109609256   14.77 14.22 11.39   ~ 829 2
16 ICRF J184208.9+794617 Sy1 18 42 08.9904975672 +79 46 17.127835104   16.06 15.38     ~ 1275 0
17 Mrk 509 Sy1 20 44 09.7504483224 -10 43 24.727155528   13.35 13.12 10.7   ~ 1223 0
18 Mrk 1513 Sy1 21 32 27.8162556672 +10 08 19.252365396   14.92 14.64     ~ 580 0
19 BD+28 4211 HS* 21 51 11.0221915656 +28 51 50.367627468 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 775 0
20 NAME BL Lac BLL 22 02 43.2913536816 +42 16 39.979416792   15.66 14.72     ~ 2169 1
21 3C 454.3 Bla 22 53 57.7480438728 +16 08 53.561508864   16.57 16.10 15.22   ~ 2727 2

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2023.01.27-18:52:19