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Register a new userReverberation Mapping of the Seyfert 1 Galaxy NGC 7469
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Added by
Bradley M. Peterson
Publication date
2014
fields
Physics
and research's language is
English
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A large reverberation mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hbeta 4861 and He II 4686 and a central black hole mass measurement of about 10 million solar masses, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hbeta measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hbeta-emitting broad-line region and the AGN luminosity. It was necessary to detrend the continuum and Hbeta and He II 4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results.
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We report results of the first reverberation mapping campaign of I Zwicky 1 during $2014$-$2016$, which showed unambiguous reverberations of the broad H$beta$ line emission to the varying optical continuum. From analysis using several methods, we obtain a reverberation lag of $tau_{rm Hbeta}=37.2^{+4.5}_{-4.9},$ days. Taking a virial factor of $f_{_{rm BLR}}=1$, we find a black hole mass of $M_{bullet}=9.30_{-1.38}^{+1.26}times 10^6 M_{odot}$ from the mean spectra. The accretion rate is estimated to be $203.9_{-65.8}^{+61.0},L_{rm Edd}c^{-2}$, suggesting a super-Eddington accretor, where $L_{rm Edd}$ is the Eddington luminosity and $c$ is the speed of light. By decomposing {it Hubble Space Telescope} images, we find that the stellar mass of the bulge of its host galaxy is $log (M_{rm bulge}/M_{odot}) = rm 10.92pm 0.07$. This leads to a black hole to bulge mass ratio of $sim 10^{-4}$, which is significantly smaller than that of classical bulges and elliptical galaxies. After subtracting the host contamination from the observed luminosity, we find that I Zw 1 follows the empirical $R_{rm BLR}propto L_{5100}^{1/2}$ relation.
NGC 7469 is a well known Luminous IR Galaxy, with a circumnuclear star formation ring ($sim 830$ pc radius) surrounding a Seyfert 1 AGN. Nuclear unresolved winds were previously detected in X-rays and UV, as well as an extended biconical outflow in IR coronal lines. We search for extended outflows by measuring the kinematics of the $mathrm{Hbeta}$ and [O III] $lambda 5007$ optical emission lines, in data of the VLT/MUSE integral field spectrograph. We find evidence of two outflow kinematic regimes: one slower regime extending across most of the star formation ring -- possibly driven by the massive star formation -- and a faster regime (with a maximum velocity of $-715 mathrm{km s^{-1}}$), only observed in [O III], in the western region between the AGN and the massive star forming regions of the ring, likely AGN-driven. This work shows a case where combined AGN/star-formation feedback can be effectively spatially-resolved, opening up a promising path toward a deeper understanding of feedback processes in the central kiloparsec of AGN.
We present our analysis of X-ray spectral properties observed from the Seyfrert 1 galactic nucleus NGC~7469 using the RXTE and ASCA observations. We demonstrate strong observational evidence that NGC~7469 undergoes spectral transitions from the low hard state (LHS) to the intermediate state (IS) during these observations. The RXTE observations (1996--2009) show that the source was in the IS ~ 75 % of the time only, ~ 25 % of the time in the LHS. The spectra of NGC~7469 are well fitted by the so-called bulk motion Comptonization (BMC) model for all spectral states. We have established the photon index saturation level, Gamma_{sat}+2.1+/-0.1, in the Gamma versus mass accretion rate, Mdot correlation. This Gamma- Mdot correlation allows us to estimate the black hole (BH) mass in NGC~7469 to be M__BH> 3 x 10^6 solar masses assuming the distance to NGC~7469 of 70 Mpc. For this BH mass estimate, we use the scaling method taking Galactic BHs, GRO~J1655--40, Cyg~ X--1 and an extragalactic BH source, NGC~4051 as reference sources. The Gamma versus Mdot correlation revealed in NGC~7469 is similar to those in a number of Galactic and extragalactic BHs and it clearly shows the correlation along with the strong Gamma saturation at ~2.1. This is robust observational evidence for the presence of a BH in NGC~7469. We also find that the seed photon temperatures are quite low, of the order of 140-200 eV, which are consistent with a high BH mass in NGC~7469 that is more than 3x10^6 solar masses.
We present new observations leading to an improved black hole mass estimate for the Seyfert 1 galaxy NGC 4593 as part of a reverberation-mapping campaign conducted at the MDM Observatory. Cross-correlation analysis of the H_beta emission-line light curve with the optical continuum light curve reveals an emission-line time delay of 3.73 (+-0.75) days. By combining this time delay with the H_beta line width, we derive a central black hole mass of M_BH = 9.8(+-2.1)x10^6 M_sun, an improvement in precision of a factor of several over past results.
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one AGN (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-Hbeta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure Hbeta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity dependent Hbeta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
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