Optical spectral characterization of the gamma-ray blazars S4 0954+65, TXS 1515-273 and RX J0812.0+0237

Abstract

The study of gamma-ray blazars is usually hindered due to the lack of information on their redshifts and on their low energy photon fields. This information is key to understand the effect on the gamma-ray absorption due to either extragalactic background light and/or intrinsic absorption and emission processes. All this information has also an impact on the determination of the location of the emitting region within the relativistic jets. In this work a new optical spectroscopic characterization is presented for three gamma-ray blazars: S4 0954+65, TXS 1515-273 and RX J0812.0+0237. For all the three targets the redshift determination is successful, and for the first time in the case of TXS 1515-273 and RX J0812.0+0237. Their classification as BL~Lac type is confirmed based on these new optical spectra. For S4 0954+65 (z=$0.3694\pm 0.0011$) an estimation on the disk, broad line region and torus luminosities is performed based on the observed optical emission lines. The results from this study are compatible with the nature of S4 0954+65 as a transitional blazar. In the case of TXS 1515-273 ($z=0.1281\pm 0.0004$), although its optical spectrum is dominated by the continuum emission from the jet, applying the pPXF technique, the stellar population can be unveiled and is compatible with an old and metallic population. It is also the case of RX J0812.0+0237 ($z=0.1721\pm 0.0002$). Moreover, this work confirms that the optical spectrum from RX J0812.0+0237 is compatible with an extreme blazar classification.

Submitted to MNRAS

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Cited by in corpus (11)

• MOJAVE XIX: Brightness Temperatures and Intrinsic Properties of Blazar Jets
• The complex variability of blazars: Time-scales and periodicity analysis in S4 0954+65
• Optical spectroscopy of Blazars for the Cherenkov Telescope Array
• Two Transient Quasi-periodic Oscillations in $\gamma$-Ray Emission from the Blazar S4 0954+658
• Detection of Quasi-Periodic Oscillations in the Blazar S4 0954+658 with TESS
• IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare
• Electron-beam interaction with emission-line clouds in blazars
• First detection of VHE gamma-ray emission from TXS~1515--273, study of its X-ray variability and spectral energy distribution
• Optical and Radio Variability of the Blazar S4 0954+658
• Investigating the origin of optical flares from the TeV blazar S4 0954+65
• Extreme Blazars Observed with MAGIC: Second Catalog Release