C. Westhues

Photometric AGN reverberation mapping – an efficient tool for BLR sizes, black hole masses, and host-subtracted AGN luminosities

Photometric reverberation mapping employs a wide band pass to measure the AGN continuum variations and a suitable narrow band to trace the echo of an emission line in the broad line region (BLR). The narrow band catches both the emission line and the underlying continuum, and one needs to extract the pure emission line light curve. We performed a test on two local AGNs, PG0003+199 and Ark120, by observing well-sampled broad- (B, V) and narrow-band light curves with the robotic 15 cm telescope VYSOS-6 on Cerro Armazones, Chile. We find that, as long as the emission line contributes 50% to the band pass, the pure emission line light curve can be reconstructed from photometric monitoring data so that the time lag τ can be measured. For both objects the lags are consistent with spectroscopic reverberation results. We calculated virial black hole masses in agreement with literature values, by combining the BLR size RBLR (τ) from photometric monitoring with the velocity dispersion of a single contemporaneous spectrum. Applying the flux variation gradient method, we estimate the host galaxy contribution in the apertures used and the host-subtracted restframe 5100 A luminosity LAGN .O urLAGN differs significantly from previous estimates, placing both sources ∼50% closer to the RBLR −LAGN relation. This suggests that the scatter in the current RBLR −LAGN relation is largely caused by uncertainties in RBLR due to undersampled light curves and by uncertainties in the host-subtracted AGN luminosities inferred so far. If the scatter can be reduced, then two quasar samples matching in RBLR should also match in intrinsic LAGN, independent of redshift, thus offering the prospect of probing cosmological models. Photometric reverberation mapping opens the door to efficiently measuring hundreds of BLR sizes and host-subtracted AGN luminosities even with small telescopes, but also routinely with upcoming large survey telescopes like the LSST.

Star formation in z > 1 3CR host galaxies as seen by Herschel

We present Herschel (PACS and SPIRE) far-infrared (FIR) photometry of a complete sample of z> 1 3CR sources, from the Herschel guaranteed time project The Herschel Legacy of distant radio-loud AGN. Combining these with existing Spitzer photometric data, we perform an infrared (IR) spectral energy distribution (SED) analysis of these landmark objects in extragalactic research to study the star formation in the hosts of some of the brightest active galactic nuclei (AGN) known at any epoch. Accounting for the contribution from an AGN-powered warm dust component to the IR SED, about 40% of our objects undergo episodes of prodigious, ULIRG-strength star formation, with rates of hundreds of solar masses per year, coeval with the growth of the central supermassive black hole. Median SEDs imply that the quasar and radio galaxy hosts have similar FIR properties, in agreement with the orientation-based unification for radio-loud AGN. The star-forming properties of the AGN hosts are similar to those of the general population of equally massive non-AGN galaxies at comparable redshifts, thus there is no strong evidence of universal quenching of star formation (negative feedback) within this sample. Massive galaxies at high redshift may be forming stars prodigiously, regardless of whether their supermassive black holes are accreting or not. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Tables 1, 2, 4 and Appendices are available in electronic form at http://www.aanda.org

Photometric reverberation mapping of 3C120

We present the results of a five month monitoring campaign of the local active galactic nuclei (AGN) 3C 120. Observations with a median sampling of two days were conducted with the robotic 15 cm telescope VYSOS-6 located near Cerro Armazones in Chile. Broad band (B, V) and narrow band (NB) filters were used in order to measure fluxes of the AGN and the Hβ broad line region (BLR) emission line. The NB flux is constituted by about 50% continuum and 50% Hβ emission line. To disentangle line and continuum flux, a synthetic Hβ light curve was created by subtracting a scaled V-band light curve from the NB light curve. Here we show that the Hβ emission line responds to continuum variations with a rest frame lag of 23.6 ± 1.69 days. We estimate a virial mass of the central black hole MBH = 57 ± 27 × 10 6 M� , by combining the obtained lag with the velocity dispersion of a single contemporaneous spectrum. Using the flux variation gradient method, we determined the host galaxy subtracted rest frame 5100 A luminosity at the time of our monitoring campaign with an uncertainty of 10% (LAGN = (6.94 ± 0.71) × 10 43 erg s −1 ). Compared with recent spectroscopic reverberation results, 3C 120 shifts in the RBLR − LAGN diagram remarkably close to the theoretically expected relation of R ∝ L 0.5 . Our results demonstrate the performance of photometric AGN reverberation mapping, in particular for efficiently determining the BLR size and the AGN luminosity.

Size and disk-like shape of the broad-line region of ESO 399-IG20

We present photometric reverberation mapping of the narrow-line Seyfert 1 galaxy ESO 399-IG20 performed with the robotic 15 cm telescope VYSOS-6 at the Cerro Armazones Observatory. Through the combination of broad- and narrow-band filters we determine the size of the broad-line emitting region (BLR) by measuring the time delay between the variability of the continuum and the Hα emission line. We use the flux variation gradient method to separate the host galaxy contribution from that of the active galactic nucleus (AGN), and to calculate the 5100 A luminosity LAGN of the AGN. Both measurements permit us to derive the position of ESO 399-IG20 in the BLR size – AGN luminosity RBLR ∝ L 0.5 AGN diagram. We infer the basic geometry of the BLR through modeling of the light curves. The pronounced sharp variability patterns in both the continuum and the emission line light curves allow us to reject a spherical BLR geometry. The light curves are best fitted by a disk-like BLR seen nearly face-on with an inclination angle of 6 ◦ ± 3 ◦ and with an extension from 16 to 20 light days.

New visual companions of solar-type stars within 25 pc

We report the discovery of faint common-proper-motion companions to the nearby southern solar-type stars HD43162, HD67199, HD114837, HD114853, HD129502, HD165185, HD197214, and HD212330 from near-infrared imaging and astrometry. We also confirm the previously identified tertiary components around HD165401 and HD188088. Since the majority of these stars were already known as binaries, they ascend now to higher-level systems. A particularly interesting case is the G6.5V BY Dratype variable HD43162, which harbors two common-proper-motion companions at distances of 410AU and 2740AU. Our limited study shows that the inventory of common-proper-motion companions around nearby bright stars is still not completely known.

Dust reverberation-mapping of the Seyfert 1 galaxy WPVS48

Using robotic telescopes of the Universitatssternwarte Bochum near Cerro Armazones in Chile, we monitored the z = 0.0377 Seyfert1 galaxy WPVS48 (2MASX J09594263-3112581) in the optical (B and R) and near-infrared (NIR, J and Ks) with a cadence of two days. The light curves show unprecedented variability details. The NIR variation features of WPVS48 are consistent with the corresponding optical variations, but the features appear sharper in the NIR than in the optical, suggesting that the optical photons undergo multiple scatterings. The J and Ks emission, tracing the hot (∼1600 K) dust echo, lags the B and R variations by on average τ = 64 ± 4 days and 71 ± 5 days, respectively (restframe). WPVS48 lies on the known τ − MV relationship. However, the observed lag τ is about three times shorter than expected from the dust sublimation radius rsub inferred from the optical-UV luminosity, and explanations for this common discrepancy are searched for. The sharp NIR echos argue for a face-on torus geometry and allow us to put forward two potential scenarios: 1) as previously proposed, in the equatorial plane of the accretion disk the inner region of the torus is flattened and may come closer to the accretion disk. 2) The dust torus with inner radius rsub is geometrically and optically thick, so that the observer only sees the facing rim of the torus wall, which lies closer to the observer than the torus equatorial plane and therefore leads to an observed foreshortened lag. Both scenarios are able to explain the factor three discrepancy between τ and rsub. Longer-wavelength dust reverberation data might enable one to distinguish between the scenarios.

The broad-line region and dust torus size of the Seyfert 1 galaxy PGC 50427

We present the results of a three years monitoring campaigns of the

Modelling photometric reverberation data: a disk-like broad-line region and a potentially larger black hole mass for 3C 120

z = 0.024

Brightness variations of the FUor-type eruptive star V346 Normae

type-1 active galactic nucleus (AGN) PGC50427. Through the use of Photometric Reverberation Mapping with broad and narrow band filters, we determine the size of the broad-line emitting region by measuring the time delay between the variability of the continuum and the H

Star Formation in 3CR Radio Galaxies and Quasars at z <1

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