J/MNRAS/489/1572ivo://CDS.VizieR/J/MNRAS/489/1572doi:10.26093/cds/vizier.74891572CDSLandt H.Ward M.J.Kynoch D.Packham C.Ferland G.J.Lawrence A.,Pott J.-U.Esser J.Horne K.Starkey D.A.Malhotra D.Fausnaugh M.M.,Peterson B.M.Wilman R.J.Riffel R.A.Storchi-Bergmann T.Barth A.J.,Villforth C.Winkler H.2024-08-20T20:12:35Z2023-02-10T12:20:37ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiseyfert-galaxiesinfrared-astronomyspectroscopyaccretionWe have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dust response times. Here we report results from a 1 yr campaign on NGC5548. The hot dust responds to changes in the irradiating flux with a lag time of ~70 light-days, similar to what was previously found in photometric reverberation campaigns. The mean and rms spectra are similar, implying that the same dust component dominates both the emission and the variations. The dust lag time is consistent with the luminosity-based dust radius only if we assume a wavelength-independent dust emissivity law, i.e. a blackbody, which is appropriate for grains of large sizes (of a few {mu}m). For such grains the dust temperature is ~1450K. Therefore, silicate grains have most likely evaporated and carbon is the main chemical component. But the hot dust is not close to its sublimation temperature, contrary to popular belief. This is further supported by our observation of temperature variations largely consistent with a heating/cooling process. Therefore, the inner dust-free region is enlarged and the dusty torus rather a 'dusty wall', whose inner radius is expected to be luminosity-invariant. The dust-destruction mechanism that enlarges the dust-free region seems to also partly affect the dusty region. We observe a cyclical decrease in dust mass with implied dust reformation times of ~5-6 months.2019MNRAS.489.1572Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/489/1572CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/489/1572https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/489/1572http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/489/1572https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/489/1572https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/489/1572http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/489/1572GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/489/1572/ngc5548 (NGC 5548)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/489/1572/ngc5548?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/489/1572/ngc5548?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/489/1572/ngc5548?GETtext/xml+votable180.050000true214.498083325.13683330.0055555555555555566/8922https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/489/1572?format=asciiInfrareddefaultJ/MNRAS/489/1572/ngc5548NGC 5548recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSimbadSimbad column added by the CDSmeta.ref.urlcharNameAGN name (NGC 5548)meta.id;meta.maincharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainLCac8700Accretion disc light curves in the 8700-9000{AA} bandmeta.ref.urlcharLCac9730Accretion disc light curves in the 9730-9790{AA} bandmeta.ref.urlcharLChd1.55Hot dust light curves in the 1.55-1.60{mu}m bandmeta.ref.urlcharLChd2.34Hot dust light curves in the 2.34-2.39{mu}m bandmeta.ref.urlcharJ/MNRAS/489/1572/tables4Near-IR spectral light curves corresponding to the accretion discrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableHJDHeliocentric Julian Date; JD-2400000dtime.epochdoublef8700Flux in the 8700-9000{AA} NIR band1e-17W.m**-2.nm**-1phot.fluxfloate_f8700Error on f87001e-17W.m**-2.nm**-1stat.errorfloatf8700corrCorrected flux in the 8700-9000{AA} NIR band (1)1e-17W.m**-2.nm**-1phot.fluxfloate_f8700corrError on f8700corr1e-17W.m**-2.nm**-1stat.errorfloatf9730Flux in the 9730-9790{AA} NIR band1e-17W.m**-2.nm**-1phot.fluxfloate_f9730Error on f97301e-17W.m**-2.nm**-1stat.errorfloatf9730corrCorrected flux in the 9730-9790{AA} NIR band (1)1e-17W.m**-2.nm**-1phot.fluxfloate_f9730corrError on f9730corr1e-17W.m**-2.nm**-1stat.errorfloatJ/MNRAS/489/1572/tables5Near-IR spectral light curves corresponding to the hot duste_f2.34subsError on f2.34subs1e-17W.m**-2.nm**-1stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableHJDHeliocentric Julian Date; JD-2400000dtime.epochdoublef1.55Flux in the 1.55-1.60{mu}m NIR band1e-17W.m**-2.nm**-1phot.fluxfloate_f1.55Error on f1.551e-17W.m**-2.nm**-1stat.errorfloatf1.55corrCorrected flux in the 1.55-1.60{mu}m NIR band (1)1e-17W.m**-2.nm**-1phot.fluxfloate_f1.55corrError on f1.55corr1e-17W.m**-2.nm**-1stat.errorfloatf1.55subsCorrected and substracted flux in the 1.55-1.60{mu}m NIR band (2)1e-17W.m**-2.nm**-1phot.fluxfloate_f1.55subsError on f1.55subs1e-17W.m**-2.nm**-1stat.errorfloatf2.34Flux in the 2.34-2.39{mu}m NIR band1e-17W.m**-2.nm**-1phot.fluxfloate_f2.34Error on f2.341e-17W.m**-2.nm**-1stat.errorfloatf2.34corrCorrected flux in the 2.34-2.39{mu}m NIR band (1)1e-17W.m**-2.nm**-1phot.fluxfloate_f2.34corrError on f2.34corr1e-17W.m**-2.nm**-1stat.errorfloatf2.34subsCorrected and substracted flux in the 2.34-2.39{mu}m NIR band (2)1e-17W.m**-2.nm**-1phot.fluxfloat