A 19952002 USAGE OF THE VLBA:

1
A 1995-2002 USAGE OF THE VLBA
GRAVITATIONAL LENSING AND COMPACT/MEDIUM
SYMMETRIC OBJECTS
Pedro Augusto1 (et al.2) 1Departamento de
Matemática e Centro de Ciências Matemáticas,
Universidade da Madeira, Caminho da Penteada,
9050 Funchal, Portugal 2Too many institutions
(see acknowledgments for names of collaborators)
0. Summary of the VLBA Observations
1
2
3

• The VLBA as the Last Word
• A 0.05-0.2 gravitational multiple imaging
  search

2. The First Unambiguous Double-Screen multiply
imaged system B2114022
Thirteen lens candidates have been ruled out with
the vital help of the VLBA (Augusto et al. 1998).
VLA (1991)
In the end of the project, no gravitational multip
le images were found...
... and the cosmological implications of
this result are presented in Augusto Wilkinson
(2001)...
MERLIN (1995)
... and the continued study of this sample
of sources is described below in a new
emerging project.
VLBA (1995-6)
The final clarification on two lens candidates,
with the vital help of the VLBA. Adapted from
Augusto et al. (1996).
3. The Ongoing Study of 1 kpc CSO/MSO Candidates
3.1 Confirmed
Although B2114022 was suspected as a lens system
since its 1991 VLA serendipitous discovery
(MERLINHST image on top), the VLBA was the
breakthrough (adapted from Augusto 1996 and
Augusto et al. 2001). The A D components are
believed to be the same multiple image, while B
C are probably physically related to the closest
of the two lenses seen with the HST (G1 at z
0.3157 G2 is at z 0.5883). For the model see
Chae et al. (2001) and Augusto et al. (2001) for
other details.
References
Augusto, P. (1996) A search for intermediate
scale gravitational lenses Ph.D. Thesis
University of Manchester (UK). Augusto,
P.,Wilkinson, P.N., Browne, I.W.A. Henstock,
D.R. (1996) The dark matter problem cannot be
solved by 106-1012 Mo black holes in Sources
and Detection of Dark Matter in the Universe
Nuclear Physics B (Proc. Supp.) 51B, 118 ed.
Cline, D.B. Elsevier Science. Augusto, P.,
Wilkinson, P.N., Browne, I.W.A. (1998)
Flat-spectrum radio sources with kpc-scale
structure MNRAS, 299, 1159-1192. Augusto, P.,
Wilkinson, P.N., Browne, I.W.A. (1999) The
population of kpc-scale flat-spectrum radio
sources in The non-Sleeping Universe Astroph.
Spa. Sc., vol. 261, p. 261-264 eds Lago,
M.T.V.T., Blanchard, A. Kluwer Academic
Pub. Augusto, P., Wilkinson, P.N. (2001) An
observational constraint on gravitational lensing
by objects of mass 109.51010..9 M0 MNRAS, 320,
L40-L44. Augusto, P. et al. (2001) B2114022
a distant radio source gravitationally lensed by
a starburst galaxy MNRAS, 326,
1007-1014. Augusto, P., Edge, A.C., Wilkinson,
P.N., Chandler, C. J. (2003a) The radio
properties of the cD galaxy of Abell 2390,
MNRAS, in prep. Augusto, P., Gonzalez-Serrano,
J.I., Edge, A.C., Perez-Fournon, I., Gonçalves,
A. L. (2003b) Compact-medium symmetric objects
with 1 kpc sizes II. Radio high resolution
imaging of 30 candidates, MNRAS, in prep. Chae,
K.-H., Mao, S., Augusto, P. (2001) Modelling
the first probable two plane lens system
B2114022 reproducing two compact radio cores A,
D MNRAS, 326, 1015-1026.
Two confirmed CSOs observed with the
MERLINVLBA (Augusto et al. 1999).
One confirmed MSO observed with the
MERLINVLBA (Augusto et al. 2003a).
3.2 Uncertain
3.3 Ruled out
Ackowledgments
Are these two sources, imaged by MERLINVLBA, a
nuclear core plus one sided jet or are they
double-hotspots (hence CSO/MSOs)?
This MERLINVLBA image shows one example of a
source that consists of a core plus
one-sided jet. Useless? Not at all.These are
excellent narrow- -line region probes via their
jets, which often show strong features.
I thank Fundação Calouste Gulbenkian (Portugal)
for the grant that allowed me to come to this
conference. I also acknowledge the Fundação para
a Ciência e a Tecnologia for the several
PhD/PostDoc/Project grants that have allowed
almost all of the work presented here to get
done. Finally, I would like to warmly acknowledge
the following collaborators (in alphabetical
order) without whom most of the work presented
would not have happened
3.4 Still reduction awaiting sources
Aparício, N., Blandford, R.D., Browne, I.W.A.,
Caires, N.B., Chae, K.-H., Chandler, C. J., de
Bruyn, A.G., Edge, A.C., Fassnacht, C.D.,
Garrett, M.A., Gizani, N.A.B., Gonçalves, A.L.,
Gonzalez-Serrano, J.I., Henstock, D.R., Hjorth,
J., Jackson, N., Jaunsen, A. O., Koopmans, L.,
Leahy, J.P., Mao, S., Marlow, D.R., Muxlow,
T.W.B., Myers, S.T., Nair, S., Patnaik, A.R.,
Pearson, T.J., Perez-Fournon, I., Polatidis,
A.G., Readhead, A.C.S., Taylor, G.B. Vermeulen,
R.C, Wilkinson, P.N., Womble, D., Xu, W.
Next month, after (lots of and prolonged)
technical problems at Univ. Madeira, data on 21
sources will be reduced. Results to be published
on Augusto et al (2003b).