J/A+A/708/A340ivo://CDS.VizieR/J/A+A/708/A340CDSSibani F.Marchesi S.Bronzini E.Ajello M.Doro M.Marcotulli L.,Prandini E.Vignali C.2026-05-04T07:43:19Z2026-04-23T09:10:57ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frbl-lacertae-objectsx-ray-sourcesWe present the results of a multi-wavelength study of a population of X-ray bright (log(F(0.2-12keV))>-12.5), non-Gamma-ray detected high and extreme high synchrotron peak (HSP, EHSP; log(Nu,peak,Hz)>16) BL Lacs to i) put stronger constraints on the synchrotron peak location and shape and ii) model their expected behaviour in the very high-energy band. First, we performed an X-ray spectral analysis, using XMM-Newton, Chandra, Swift-XRT, and eROSITA data, and fitting the spectra using both a power law and a log parabola model. Out of 78 sources in the initial sample, 17 were best described by a log parabola model, a result that supports a scenario where the synchrotron peak falls in the X-ray band. Among these 17 sources, we further selected the 10 objects dominated by the jet emission, with no significant contamination of the host galaxy. We performed a gamma-ray analysis of Fermi-LAT data for these objects, obtaining upper limits providing information on their flux in the 100MeV-300GeV energy range. We then modelled the broadband SED of these objects with JetSeT using two models: one assuming a log parabola for the electron distribution and the other one with a broken power law electron distribution, using parameters consistent with those describing the emission of the prototypical EHSP 1ES 0229+200. We found the models to be generally consistent with the available multi-wavelength detections and upper limits. Furthermore, they confirmed that a subsample of sources could display relevant emission in the TeV energy range, even potentially reaching the threshold for detectability by the Cherenkov Telescope Array Observatory.2026A&A...708A.340Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/708/A340CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/708/A340https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/708/A340http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/708/A340https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/708/A340https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/708/A340http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/708/A340GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/708/A340/catalog (Catalog of 95 X-ray spectral fits of 78 high synchrotron peak blazars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/708/A340/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/708/A340/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/708/A340/catalog?GETtext/xml+votable180.050000true10.0683333-27.31988890.0055555555555555566/975 4141 4612 4638 5349 5676 5698 5800 6242 6487 6529 6848 8714 9104 9168 9406 9455 9732 10061 10510 10748 10805 11064 11126 11514 16649 16952 18324 18749 18852 19099 19411 20550 23181 24681 24870 26087 26221 26247 26282 26335 26520 26596 26650 27145 27246-27247 27428 27653 27659 27726 27797 28343 28478 28481 30772 31389 31472 34531 36117 38199 43945 46481 46510 46629 46736 46994 48316 48975 49019https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/708/A340?format=asciiX-raydefaultJ/A+A/708/A340/catalogCatalog of 95 X-ray spectral fits of 78 high synchrotron peak blazarsSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension (J2000), 5BZCAT source (RA_5BZCAT)pos.eq.ra;meta.mainDEJ2000Declination (J2000), 5BZCAT source (DEC_5BZCAT)pos.eq.dec;meta.mainz? Source redshift (Redshift)src.redshiftfloatnullableSpecIDSpectrum ID for sources where multiple X-ray spectra where analysed; if a single observation was available, the flag is 0 (Spec_ID)meta.idintrefsrcIDSource ID from the given X-ray source catalog, when available (Reference_src_ID)meta.ref;pos.framecharlognuPeakLogarithm of the blazar SED synchrotron peak computed using the Blazar Synchrotron Tool, BlaST. From Marchesi et al. (2025A&A...693A.142M, Cat. J/A+A/693/A142) (nu_peak)log(Hz)em.freqfloatGamma? Best-fit photon index from a power law fit of the X-ray spectrum (Gamma)meta.code;spect.index;meta.modelledfloatnullablecstat-pl? Best-fit Cstat value from the power law fit (cstat_pl)stat.fit.paramfloatnullablee_Gamma[] 90% confidence level lower error on the photon index (Gamma_err_lo)stat.errorfloatE_Gamma90% confidence level upper error on the photon index (Gamma_err_up)stat.error;stat.maxfloatdof-pl? Degrees of freedom from the power law fit (dof_pl)stat.fit.dofintnullablealpha? Best-fit alpha parameter from a logparabola fit of the X-ray spectrum (alpha)stat.fit.paramfloatnullablee_alpha[] 90% confidence level lower error on the alpha parameter (alpha_err_lo)stat.error;pos.eq.rafloatE_alpha90% confidence level upper error on the alpha parameter (alpha_err_up)stat.error;stat.maxfloatbeta? Best-fit beta parameter from a logparabola fit of the X-ray spectrum (beta)stat.fit.paramdoublenullablee_beta[] 90% confidence level lower error on the beta parameter (beta_err_lo)stat.errorfloatE_beta90% confidence level lower error on the beta parameter (beta_err_up)stat.error;stat.maxfloatcstat-lp? Best-fit Cstat value from the logparabola fit (cstat_lp)stat.fit.paramfloatnullabledof-lp? Degrees of freedom from the logparabola fit (dof_lp)stat.fit.dofintnullableFlux03-8keV? Best-fit value of the observed 0.3-8keV flux from the logparabola fit (flux_03_8_keV)log(1e-15W.m**-2)phot.flux;em.X-raydoublenullableb_Flux03-8keV90% confidence level lower boundary of the observed 0.3-8keV flux from the logparabola fit (flux_03_8_keV_low_bound)log(1e-15W.m**-2)phot.flux;em.X-ray.medium;phys.atmol.leveldoubleB_Flux03-8keV90% confidence level upper boundary of the observed 0.3-8keV flux from the logparabola fit (flux_03_8_keV_up_bound)log(1e-15W.m**-2)phot.flux;em.X-ray.medium;phys.atmol.leveldoublelogLX2-10keV? Best-fit value of the logarithm of the rest-frame, intrinsic 2-10keV luminosity from the logparabola fit (logLx_2_10_keV)log(1e-07W)phot.flux;em.X-rayfloatnullablee_logLX2-10keV[] 90% confidence level lower error on the logarithm of the rest-frame, intrinsic 2-10keV luminosity from the logparabola fit (logLx_2_10_keV_err_lo)log(1e-07W)stat.errorfloatE_logLX2-10keV90% confidence level upper error on the logarithm of the rest-frame, intrinsic 2-10 keV luminosity from the logparabola fit (logLx_2_10_keV_err_up)log(1e-07W)stat.error;stat.maxfloatDeltaCstat? Difference in Cstat between the power law and the logparabola best fits (DeltaCstat)stat.fit.paramfloatnullable5BZCAT5BZCAT source ID, from Massaro et al. (2015Ap&SS.357...75M, Cat. VII/274) (ID_5BZCAT)meta.id;meta.maincharInstX-ray telescope used to obtain the spectrum (Instrument)instr.setupcharObsIDObservation ID for sources with multiple observations from the same instrument (ObsID)meta.id;obschar