An ASCA observation of the radio-loud narrow-line Seyfert 1 galaxy RGB J0044+193

Narrow-line Seyfert 1 galaxies are generally found to be radio-quiet and th ere was only one radio-loud object known so far (PKS 0558-504). Here we pre sent the results of a 50 ksec ASCA observation of the recently discovered s econd radio-loud NLS1 galaxy RGB J0044+193. The X-ray data are complemented by radio observations and a new optical spectrum for this source. We find evidence for variable radio emission and an inverted radio spectrum of RGB J0044+193. The optical continuum turned out to be extremely blue. T his may either indicate additional line emission, for example from Fe I, or scattering of a blue intrinsic continuum. The X-ray spectrum shows a clear break around 1.8 keV. Above this energy the spectrum is characterized by a power law with a photon index of Gamma approximate to 2.1. For energies be low 2 keV the spectrum is much softer and it can either be modeled with a s teeper power law (Gamma approximate to 2.7) or a blackbody component with a temperature around 0.2 keV. The X-ray count rate of the source decreased b y a factor of two within one day and there is evidence for low amplitude va riability on much shorter time scales. Given its average 2-10 keV X-ray lum inosity of (1.35 +/- 0.05) x 10(44) erg s(-1), RGB J0044+193 is significant ly more variable than a typical broad line Seyfert 1 galaxy of comparable X -ray luminosity, but consistent with the bulk of NLS1 galaxies. The spectral as well as the variability properties of RGB J0044+193 are ind istinguishable from those of radio-quiet NLS1s. In particular, we find no e vidence for a flat X-ray component due to inverse Compton emission related to the putative non-thermal radio emission from RGB J0044+193. We argue, ho wever, that this does nut rule out a pole-on orientation for RGB J0044+193.