Astron. Astrophys. 356, 11-22 (2000)
5. Summary and conclusions
We have presented the results of our ROSAT, ASCA and optical
observations of the enigmatic soft X-ray AGN RX J0134.2-4258. We
RX J0134.2-4258 has shown a dramatic change in its ROSAT PSPC
spectra between its RASS and a pointed PSPC observation made two years
Optically, RX J0134.2-4258 is a Narrow-Line Seyfert 1 galaxy with
very strong FeII emission, extremely weak emission from the NLR and
with a very blue optical continuum.
The slopes of the hard component of the ROSAT spectra and the ASCA
spectra are consistent, and the ASCA slope is notably flat compared
with other NLS1s.
It is the normalization of the hard X-ray component that varies the
most and is primarily responsible for the dramatic spectral
RX J0134.2-4258 has been found to be one of the few NLS1s that are
radio loud, and currently holds the record for radio-to-optical flux
ratio in NLS1s.
Physical reasons for the strange spectral behaviour might be a
variable warm absorber, the loss and regrowth of a corona above the
accretion disk, or an increase in flux from a component associated
with a possible jet as indicated by the radio-loudness of this
One important problem that applies to most transient AGN is that it
is difficult to monitor their behaviour. Often years lapsed between
RASS and later pointed observations. Hopefully, in the future with new
survey missions it will be easier and faster to discover transients.
Then they could be monitored using next-generation all sky monitor
experiments such as the approved mission MAXI which will be mounted on
the Japanese Experimental Module of the International Space Station,
or the proposed Lobster-Eye satellite.
© European Southern Observatory (ESO) 2000
Online publication: March 28, 2000