Long-term Swift and multiwavelength observations of two TeV-detected blazars with unknown redshifts

**Authors:** Sergo Kapanadze **Affiliations:** Georgian National Astrophysical Observatory, Abastumani 0301, Georgia The paper presents the spectral and timing results for two TeV-detected blazars of unknown redshift RGB J0136+391 and H1722+119, which are based on long-term multiwavelength (MWL) observations carried out with several space and ground-based instruments. The sources showed a strong variability in the 0.3-12 keV energy range. The X-ray spectra were generally soft with a photon index higher than 2.0 and exhibited a synchrotron peak position in the UV—soft X-ray range (Ep<2 keV). H1722+119 demonstrated a very weak harder-when-brighter spectral trend that could be related to the emergence of soft X-ray components during the 0.3-10 keV flares. While the source mostly showed power-law spectra in this band (possibly formed by the first-order Fermi mechanism), RGB J0136+391 demonstrated the importance of stochastic acceleration and logparabolic spectra with low curvatures (a curvature parameter b∼0.3), as well as a significantly stronger harder-when-brighter spectral evolution.