1999A&AS..135..477R


Query : 1999A&AS..135..477R

1999A&AS..135..477R - Astron. Astrophys., Suppl. Ser., 135, 477-486 (1999/March-2)

Optical microvariability of southern AGNs.

ROMERO G.E., CELLONE S.A. and COMBI J.A.

Abstract (from CDS):

We present results of a search for optical microvariability in a selected sample of 23 southern AGNs, which includes both radio-quiet and radio-loud objects. Microvariations were clearly detected in 60% of the radio-loud sources, with amplitudes from 2.2% up to 8% within a single night. Night-to-night variability with amplitudes of ∼20% was also observed in the BL Lac object 0537-441. On the contrary, no rapid variability was detected at all in 8 radio-quiet quasars. We have used microvariability data previously reported for northern objects along with our new results for southern AGNs in order to estimate duty cycles of each class of objects from the largest possible sample. Most of the microvariability in radio-loud objects could be originating in interactions between relativistic shocks and features in the inner jets, although contributions from superluminal microlensing and accretion disk instabilities can be present in some sources. It is possible that the latter phenomenon is responsible for the microvariability observed in northern radio-quiet quasars. We suggest that the difference in the microvariability behaviour of radio and X-ray selected BL Lacs could be due to the effect of stronger magnetic fields in the latter group of objects, fields that can prevent the formation of features like density inhomogeneities and bends in the base of the jets by Kelvin-Helmholtz macroscopic instabilities.

Abstract Copyright:

Journal keyword(s): galaxies: active - BL Lacertae objects: general - quasars: general - galaxies: photometry

CDS comments: Fig. 1 : comparison stars not in SIMBAD.

Simbad objects: 22

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Number of rows : 22
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 QSO B0537-441 BLL 05 38 50.36155950 -44 05 08.9390233   15.77 16.48 16   ~ 888 2
2 QSO J0635-7516 Bla 06 35 46.5079301472 -75 16 16.816418256   15.96 15.75 15.82   ~ 595 1
3 QSO B1034-293 QSO 10 37 16.07974265 -29 34 02.8134977   16.46 16.46 17.54   ~ 343 1
4 QSO J1103-2329 BLL 11 03 37.6150845072 -23 29 31.203773520   17.00 16.55 16.61   ~ 382 2
5 QSO B1120-272 QSO 11 23 02.2875547152 -27 30 04.264832952     16.8     ~ 9 0
6 HE 1125-3028 QSO 11 27 31.8118748328 -30 44 45.688753644     16.3     ~ 9 0
7 QSO J1130-1449 Bla 11 30 07.0523452128 -14 49 27.388021944   17.17 16.90 16 16.97 ~ 713 1
8 QSO B1144-3755 BLL 11 47 01.37071212 -38 12 11.0235229   19.03 16.2 16.72   ~ 303 1
9 HE 1157-2955 QSO 11 59 43.3607510688 -30 11 52.204369344     16.4     ~ 14 0
10 QSO J1246-2547 QSO 12 46 46.80203943 -25 47 49.2889822   17.65 17.41 16.96 15.5 ~ 289 1
11 QSO B1256-229 BLL 12 59 08.46204170 -23 10 38.6543799   18.0   15.9   ~ 52 1
12 LEDA 3096297 Sy1 13 52 59.7241134936 -44 13 26.171526972     15.45     ~ 21 2
13 QSO J1512-0906 Bla 15 12 50.53293048 -09 05 59.8297908   16.74 16.54     ~ 1324 1
14 QSO B1519-273 BLL 15 22 37.67599511 -27 30 10.7855131   18.72 18.5 17.42   ~ 298 1
15 QSO B2005-489 BLL 20 09 25.3903899240 -48 49 53.725051056   15.75 12.81 11.41   ~ 579 2
16 QSO B2155-304 BLL 21 58 52.0652249880 -30 13 32.118447792   13.36 13.09 12.62   ~ 1743 1
17 EC 22004-1816 HS* 22 03 11.5438329552 -18 01 43.957998480       15.60   sdO 15 1
18 MCG-07-47-031 BLL 23 19 05.8954756632 -42 06 48.297034584   16.60 15.46     ~ 114 0
19 [VV96] J234313.6-464003 QSO 23 43 13.5844609152 -46 40 02.985365892   16.4 16.4     ~ 6 0
20 [VV96] J234347.0-440719 QSO 23 43 46.9576016592 -44 07 19.152759612   16.5 16.5     ~ 6 0
21 [VV96] J234640.5-461230 QSO 23 46 40.6001055168 -46 12 30.113800452   16.4 16.4     ~ 6 0
22 QSO B2347-4342 QSO 23 50 34.2593744544 -43 25 59.683985652   16.3 16.3     ~ 170 0

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