Monitoring of the optical and 2.5-11.7 mu m spectrum and mid-IR imaging of the Seyfert 1 galaxy Mrk 279 with ISO
European Space Research and Technology Centre1, European Southern Observatory2, Harvard University3, University of Arizona4, Ohio State University5, Goddard Space Flight Center6, University of Leicester7, Tel Aviv University8, University of St Andrews9, Space Telescope Science Institute10, Johns Hopkins University11, University of California, Los Angeles12, Isaac Newton Institute13, Shanghai Astronomical Observatory14, European University of Madrid15
01 Apr 2001-Vol. 369, Iss: 1, pp 57-64
TL;DR: In this article, mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 mum spectrum.
Abstract: Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 mum spectrum. Contemporaneous optical photometric and spectrophotometric observations are also presented. The galaxy appears as a point-like source at the resolution of the ISOCAM instrument (4-5 "). The 2.5-11.7 mum average spectrum of the nucleus in Mrk 279 shows a strong power law continuum with alpha = -0.80 +/- 0.05 (F nu proportional to nu (alpha)) and weak PAK emission features. The Mrk 279 spectral energy distribution shows a mid-IR bump, which extends from 2 to 15-20 mum The mid-IR bump is consistent with thermal emission from dust grains at a distance of greater than or similar to 100 It-d. No significant variations of the mid-IR flux have been detected during our observing campaign, consistent with the relatively low amplitude (similar to 10% rms) of the optical variability during the campaign. The time delay for H beta line emission in response to the optical continuum variations is tau = 16.7(-5.6)(+5.3), days, consistent with previous measurements.
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University of California, Los Angeles1, Harvard University2, University of Auckland3, University of California, Irvine4, California Polytechnic State University5, University of Utah6, Brigham Young University7, University of California, Riverside8, Goddard Space Flight Center9, University of Maryland, College Park10, University of California, Berkeley11, University of Southampton12, Western Kentucky University13, University of Northern Colorado14, Space Telescope Science Institute15, Texas A&M University16, Seoul National University17
TL;DR: In this paper, the authors present models of the Hβ-emitting broadline region (BLR) in seven Seyfert 1 galaxies from the Lick AGN Monitoring Project 2011 sample, drawing inferences on the BLR structure and dynamics as well as the mass of the central supermassive black hole.
Abstract: We present models of the Hβ-emitting broad-line region (BLR) in seven Seyfert 1 galaxies from the Lick AGN Monitoring Project 2011 sample, drawing inferences on the BLR structure and dynamics as well as the mass of the central supermassive black hole. We find that the BLR is generally a thick disk, viewed close to face-on, with preferential emission back toward the ionizing source. The dynamics in our sample range from near-circular elliptical orbits to inflowing or outflowing trajectories. We measure black hole masses of for PG 1310-108, for Mrk 50, for Mrk 141, for Mrk 279, for Mrk 1511, for NGC 4593, and for Zw 229-015. We use these black hole mass measurements along with cross-correlation time lags and line widths to recover the scale factor f used in traditional reverberation mapping measurements. Combining our results with other studies that use this modeling technique, which brings our sample size to 16, we calculate a scale factor that can be used for measuring black hole masses in other reverberation mapping campaigns. When using the root-mean-square (rms) spectrum and using the line dispersion to measure the line width, we find pred = 0.57 0.19. Finally, we search for correlations between f and other AGN and BLR parameters and find marginal evidence that f is correlated with M BH and the BLR inclination angle, but no significant evidence of a correlation with the AGN luminosity or Eddington ratio.
73 citations
Cites background from "Monitoring of the optical and 2.5-1..."
...Santos-Lleó et al. (2001) observed Mrk 279 from 1996 to 1997 and measured an Hβ time lag of τ = 16+5.3−5.6 days....
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TL;DR: In this paper, a comparison of six high-redshift quasar spectra obtained with the Large Binocular Telescope (LBT) with previous observations from the Sloan Digital Sky Survey (SDS) showed that failure to correctly identify absorption and other problems with accurate characterization of the C IV λ1549 emission line profile in low signal-to-noise (S/N) data can severely limit the reliability of single-epoch mass estimates based on the CIV emission line.
Abstract: Comparison of six high-redshift quasar spectra obtained with the Large Binocular Telescope with previous observations from the Sloan Digital Sky Survey shows that failure to correctly identify absorption and other problems with accurate characterization of the C IV λ1549 emission line profile in low signal-to-noise (S/N) data can severely limit the reliability of single-epoch mass estimates based on the C IV emission line. We combine the analysis of these new high-quality data with a reanalysis of three other samples based on high-S/N spectra of the C IV emission line region. We find that a large scatter between the Hβ- and C IV-based masses remains even for this high-S/N sample when using the FWHM to characterize the broad-line region velocity dispersion and the standard virial assumption to calculate the mass. However, we demonstrate that using high-quality data and the line dispersion to characterize the C IV line width leads to a high level of consistency between C IV- and Hβ-based masses, with <0.3 dex of observed scatter and an estimated ~0.2 dex intrinsic scatter, in the mass residuals.
70 citations
TL;DR: In this paper, two new empirical relations were introduced to estimate the central black hole masses of radio-loud high-redshift (z> 0.5) AGNs.
Abstract: Based on measuredbroad line region sizes in the reverberation-mappingAGN sam- ple, two new empirical relations are introduced to estimate the central black hole masses of radio-loud high-redshift ( z> 0.5) AGNs. First, using the archival IUE /HST spectroscopy data at UV band for the reverberation-mapping objects, we obtained two new empirical re- lations between the BLR size and Mg II/C IV emission line luminosity. Secondly, using the newly determined black hole masses of the reverberation-mappingsample as calibration, we found two new relationships for determining the black hole mass with the full width at half maximum and the luminosity of Mg II/C IV line. We then apply the relations to estimate the black hole masses of the AGNs in the Large Bright Quasar Survey and a sample of radio-loud quasars. For the objects with small radio-loudness, the black hole mass estimated using the RBLR-LMg II/ CI Vrelation is consistent with that from the RBLR-L 3000 ˚ A/1350 ˚ A relation. For radio-loud AGNs, however, the mass estimated from the R BLR-LMg II/ CI V relation is sys- tematically lower than that from the continuumluminosity L 3000 ˚ A/1350 ˚ A. Because jets could have significant contributions to the UV/optical continuum luminosity of radio-loud AGNs, we emphasize once again that for radio-loud AGNs, the emission line luminosity may be a better tracer of the ionizing luminosity than the continuum luminosity, so that the relations between the BLR size and UV emission line luminosities should be used to estimate the black hole masses of high redshift radio-loud AGNs.
67 citations
TL;DR: In this article, the optical variability of six narrow-line Seyfert 1 (NLS1) galaxies observed at 172 epochs was studied. But the authors found that the variability in NLS1's is rare and of low amplitude.
Abstract: We present results of a broadband photometric study of the optical variability of six narrow-line Seyfert 1 (NLS1) galaxies observed at 172 epochs. We searched for microvariability on 33 nights. Strong evidence for microvariability was found only for our lowest luminosity object, NGC 4051, on one night. Weaker evidence suggests such variability on a few other nights for two other objects, but the data are not as convincing. Intranight variability in NLS1's is thus concluded to be rare and of low amplitude. We give illustrations of how variable image quality can produce spurious variability. We find that for well-studied non-NLS1's there is a spread in the amplitude of seasonal variability (i.e., in some years an active galactic nucleus [AGN] is more variable than in others). We find that the means of the variability amplitudes of non-NLS1's over several seasons vary from object to object (i.e., some AGNs are, on average, more variable than others). NLS1's also show a spread in seasonal variabilities. The best-studied NLS1, Ark 564, shows a range of amplitudes of variability from season to season that is comparable to the range found in broad-line Seyfert 1 galaxies (BLS1's), and in one season Ark 564 was as variable as the most variable non-NLS1. The seasonal amplitudes of variability for NLS1's are mostly in the lower half of the range of non-BLS1 seasonal amplitudes, but the absence of a suitable control sample makes a precise comparison difficult. However, on long timescales (weeks to years) NLS1's as a class are not more variable than non-NLS1's. The extreme variability seen in the X-rays was not seen in the optical. This has consequences for the models of AGNs in general as well as NLS1's in particular.
61 citations
University of Padua1, Space Telescope Science Institute2, Ohio State University3, Georgia State University4, Pennsylvania State University5, University of Connecticut6, University of Arizona7, York University8, University of St Andrews9, Peking University10, University of Illinois at Urbana–Champaign11, University of Atacama12, University of Copenhagen13
TL;DR: In this paper, the authors compare mass estimates based on line dispersion and FWHM, and show that the luminosity of the Hbeta broad component can be used instead without any loss of precision, thus eliminating the difficulty of accurately accounting for the host-galaxy contribution to the observed luminosity.
Abstract: It is well known that reverberation mapping of active galactic nuclei (AGN) reveals a relationship between AGN luminosity and the size of the broad-line region, and that use of this relationship, combined with the Doppler width of the broad emission line, enables an estimate of the mass of the black hole at the center of the active nucleus based on a single spectrum. An unresolved key issue is the choice of parameter used to characterize the line width, either FWHM or line dispersion (the square root of the second moment of the line profile). We argue here that use of FWHM introduces a bias, stretching the mass scale such that high masses are overestimated and low masses are underestimated. Here we investigate estimation of black hole masses in AGNs based on individual or "single epoch" observations, with a particular emphasis in comparing mass estimates based on line dispersion and FWHM. We confirm the recent findings that, in addition to luminosity and line width, a third parameter is required to obtain accurate masses and that parameter seems to be Eddington ratio. We present simplified empirical formulae for estimating black hole masses from the Hbeta 4861 A and C IV 1549 A emission lines. While the AGN continuum luminosity at 5100 A is usually used to predict the Hbeta reverberation lag, we show that the luminosity of the Hbeta broad component can be used instead without any loss of precision, thus eliminating the difficulty of accurately accounting for the host-galaxy contribution to the observed luminosity.
56 citations
References
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TL;DR: In this article, a method for measuring correlation functions without interpolating in the temporal domain is proposed which provides an assumption-free representation of the correlation measured in the data and allows meaningful error estimates.
Abstract: A method for measuring correlation functions without interpolating in the temporal domain is proposed which provides an assumption-free representation of the correlation measured in the data and allows meaningful error estimates. Physical interpretation of the cross-correlation function of two series believed to be related by a convolution is shown to require knowledge of the input function's fluctuation power spectrum. Application of the method to two systems reveals no correlation for the optical data of Akn 120, but a strong correlation for the UV data of NGC 4151, placing bounds of between 1.2 and 20 light days on the size of the line-emitting region.
1,139 citations
TL;DR: In this paper, a procedure is described for analyzing a time series of measurements of both the continuum and the emission lines, and it is shown that if the emission line region has a high degree of symmetry, then it is possible to invert the time-dependent line profiles and obtain the phase space distribution of the emission-line gas.
Abstract: Variations in the strengths of the central photoionization source in a quasar or Seyfert galaxy will generate variations in the strengths and profiles of the emission lines. These ''reverberations'' in the emission lines will lag behind the continuum variations due to light travel time effects. A procedure is described for analyzing a time series of measurements of both the continuum and the lines. This procedure permits direct verification of the assumed causal connection of the lines to the continuum. We demonstrate that if the emission line region has a high degree of symmetry, then it is possible to invert the time-dependent line profiles and obtain the phase space distribution of the emission-line gas: i.e., its emissivity and the moments of its velocity distributions as functions of position. The cases of spherical and disk symmetry are considered in detail; the case of a straight jet, which may be relevent to correlated optical and radio variations, is discussed briefly. Explicit calculations of expected line variations have been carried out for several simple models. We suggest that with recently developed instrumentation it should now be possible to apply this technique to Seyfert galaxies. Long term, highly accurate observations will be required for themore » application to quasars.« less
1,034 citations
"Monitoring of the optical and 2.5-1..." refers methods in this paper
...Reverberation-mapping techniques (Blandford & McKee 1982) have been used extensively to map the BLR in several AGN, on scales of light days to light months, notably by the International AGN Watch1 consortium (Alloin et al. 1994)....
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01 Jun 1988
TL;DR: It is shown that physical interpretation of active galactic nuclei cross-correlation functions requires knowledge of the input function's fluctuation power spectrum, involves model-dependence in the form of symmetry assumptions, and must take into account intrinsic scale bias.
Abstract: A method of measuring correlation functions without interpolating in the temporal domain, the discrete correlation function, is introduced. It provides an assumption-free representation of the correlation measured in the data, and allows meaningful error estimates. This method does not produce spurious correlations at zero lag due to correlated errors. It is shown that physical interpretation of active galactic nuclei cross-correlation functions requires knowledge of the input function's fluctuation power spectrum, involves model-dependence in the form of symmetry assumptions, and must take into account intrinsic scale bias. This technique was used to find a correlation in published IUE data for NGC 4151, which indicates that the broad C IV feature emanates from a shell 15 to 75 light-days in radius, assuming spherical symmetry.
818 citations
"Monitoring of the optical and 2.5-1..." refers methods in this paper
...We used both the interpolation method of Gaskell & Sparke (1986) and the discretecorrelation function (DCF) method of Edelson & Krolik (1988), in both cases employing the specific implementation described by White & Peterson (1994)....
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TL;DR: In this article, the authors show that most of the bright quasars from the Palomar-Green (PG) survey appear to emit the bulk of their luminosity (typically more than 90%) between 3 nm and 300 μm (10.7-10^(18) Hz).
Abstract: Continuum observations from ~0.3 nm to 6 cm (10^(9.7)-10^(18) Hz) are presented for 109 bright quasars from the Palomar-Green (PG) survey. Two-thirds of the quasars have been detected in the infrared at wavelengths
between 10 and 100 μm. All of the PG quasars appear to emit the bulk of their luminosity (typically more than 90%) between 3 nm and 300 μm (10^(12)-10^(17) Hz). The total luminosity at wavelengths longer than 1 μm is typically 20%-40% of that at wavelengths shortward of 1 μm. The gross shape of the energy distributions between 3 nm and 300 μm is remarkably similar for all the quasars except the flat-spectrum radio-loud quasars like 3C 273 and can plausibly be fitted by two broad components of thermal emission. In this interpretation the emission in the spectral range ~ 10 nm to 0.3 μm, the "big blue bump," is dominated by 10,00-100,000 K thermal emission from an accretion disk. The emission between 2 μm and 1 mm, the "infrared bump," is made up of reradiation from dust in a distorted disk extending from 0.1 pc to more than 1 kpc. The fairly small range in the relative sizes of the bumps suggests that the covering factor in most of the PG quasars is similar. There is no obvious connection between the strengths of the blue and infrared peaks and whether or not the quasar is radio quiet or radio loud. The mass
of infrared emitting dust is estimated to be ~0.01 M_☉ at 2 μm and ~ 10^5 M_☉ at 60 μm. The radiation from 0.5 μm is thermal emission from the portion of the disk between 0.1 and 1 pc, illuminated primarily by the clouds of the broad-line region. The radiation from 5 μm to 1 mm is reradiation from a warped disk at distances greater than 1 pc from the central source, which is heated directly by radiation from the central source. Optically thin atomic emission (free-free and partially thermalized lines and bound-free) from gas within 1 pc of the central source, whose dust has sublimated, probably contributes to the flux from 0.5 to 2 μm. We believe that there is no convincing evidence for energetically significant nonthermal radiation in the wavelength range 3 nm to 300 μm in the continua of the radio-quiet and steep-spectrum radio-loud PG quasars.
648 citations
"Monitoring of the optical and 2.5-1..." refers background in this paper
...The presence of a universal inflection point near 1.2µm in the spectral energy distribution of radio-quiet AGN’s strongly suggests that the bulk of the near IR flux arises from dust thermal emission (e.g., Barvainis 1987; Sanders et al. 1989)....
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TL;DR: In this paper, thermal radiation by dust can reproduce the overall shape of the bump seen in the near-infrared continua of many QSOs and AGN, and a simple model in which dust grains are heated by the primary nuclear optical/ultraviolet continuum produces the required emission at short wavelengths.
Abstract: It is shown here that thermal radiation by dust can reproduce the overall shape of the bump seen in the near-infrared continua of many QSOs and AGN. A simple model in which dust grains are heated by the primary nuclear optical/ultraviolet continuum produces the required emission at short wavelengths. The model naturally explains the onset of the bump at about 2 microns. This wavelength corresponds to the optically thin emission peak for the hottest possible grains, i.e., graphite grains at their evaporation temperature near 1500 K. Emission longward of 2 microns is due to cooler grains farther from the central source. 33 references.
644 citations
"Monitoring of the optical and 2.5-1..." refers background in this paper
...The presence of a universal inflection point near 1.2µm in the spectral energy distribution of radio-quiet AGN’s strongly suggests that the bulk of the near IR flux arises from dust thermal emission (e.g., Barvainis 1987; Sanders et al. 1989)....
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