Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userReverberation Mapping Measurements of Black Hole Masses and Broad-Line Region Kinematics in Mrk 817 and NGC 7469
197
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present the results from a spectroscopic monitoring campaign to obtain reverberation-mapping measurements and investigate the broad-line region kinematics for active galactic nuclei (AGN) of Mrk~817 and NGC~7469. This campaign was undertaken with the Lijiang 2.4-meter telescope, the median spectroscopic sampling is 2.0 days for Mrk~817 and 1.0 days for NGC~7469. We detect time lags of the broad emission lines including H$beta$, H$gamma$, He~{sc ii} and He~{sc i} for both AGNs, and including Fe~{sc ii} for Mrk~817 with respect to the varying AGN continuum at 5100~AA. Investigating the relationship between line widths and time lags of the broad emission lines, we find that the BLR dynamics of Mrk~817 and NGC~7469 are consistent with the virial prediction. We estimate the masses of central supermassive black hole (SMBH) and the accretion rates of both AGNs. Using the data of this campaign, we construct the velocity-resolved lag profiles of the broad H$gamma$, H$beta$, and He~{sc i} lines for Mrk~817, which show almost the same kinematic signatures that the time lags in the red wing are slightly larger than the time lags in the blue wing. For NGC~7469, we only clearly construct the velocity-resolved lag profiles of the broad H$gamma$ and H$beta$, which show very similar kinematic signatures to the BLR of Mrk~817. These signatures indicate that the BLR of Keplerian motion in both AGNs seemingly has outflowing components during the monitoring period. We discuss the kinematics of the BLR and the measurements including SMBH mass and accretion rates.
rate research
Read More
We report the results of a multi-year spectroscopic and photometric monitoring campaign of two luminous quasars, PG~0923+201 and PG~1001+291, both located at the high-luminosity end of the broad-line region (BLR) size-luminosity relation with optical luminosities above $10^{45}~{rm erg~s^{-1}}$. PG~0923+201 is for the first time monitored, and PG~1001+291 was previously monitored but our campaign has a much longer temporal baseline. We detect time lags of variations of the broad H$beta$, H$gamma$, Fe {sc ii} lines with respect to those of the 5100~{AA} continuum. The velocity-resolved delay map of H$beta$ in PG~0923+201 indicates a complicated structure with a mix of Keplerian disk-like motion and outflow, and the map of H$beta$ in PG~1001+291 shows a signature of Keplerian disk-like motion. Assuming a virial factor of $f_{rm BLR}=1$ and FWHM line widths, we measure the black hole mass to be $118_{-16}^{+11}times 10^7 M_{odot}$ for PG~0923+201 and $3.33_{-0.54}^{+0.62}times 10^7 M_{odot}$ for PG~1001+291. Their respective accretion rates are estimated to be $0.21_{-0.07}^{+0.06} times L_{rm Edd},c^{-2}$ and $679_{-227}^{+259}times L_{rm Edd},c^{-2}$, indicating that PG~0923+201 is a sub-Eddington accretor and PG~1001+291 is a super-Eddington accretor. While the H$beta$ time lag of PG~0923+201 agrees with the size-luminosity relation, the time lag of PG~1001+291 shows a significant deviation, confirming that in high-luminosity AGN the BLR size depends on both luminosity and Eddington ratio. Black hole mass estimates from single AGN spectra will be over-estimated at high luminosities and redshifts if this effect is not taken into account.
Reverberation results of a flat spectrum radio quasar PKS 1510-089 are presented from 8.5-years long spectroscopic monitoring carried out in 9 observing seasons between December 2008 to June 2017 at Steward Observatory. Optical spectra show strong H$beta$, H$gamma$, and Fe II emission lines overlaying on a blue continuum. All the continuum and emission line light curves show significant variability with a fractional root-mean-square variation of $37.30pm0.06$% ($f_{5100}$), $11.88pm0.29$% (H$beta$) and $9.61pm0.71$% (H$gamma$), however, along with thermal radiation from accretion disk non-thermal emission from jet also contribute to $f_{5100}$. Several methods of time series analysis (ICCF, DCF, von Neumann, Bartels, JAVELIN, $chi^2$) are used to measure lag between continuum and line light curves. The observed frame BLR size is found to be $61.1^{+4.0}_{-3.2}$ ($64.7^{+27.1}_{-10.6}$) light-days for H$beta$ (H$gamma$). Using $sigma_{mathrm{line}}$ of $1262pm247$ km s$^{-1}$ measured from the rms spectrum, the black hole mass of PKS 1510-089 is estimated to be $5.71^{+0.62}_{-0.58} times 10^{7} M_{odot}$.
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range ~10^6-10^7 M_sun and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hbeta emission. We present here the light curves for the objects in this sample and the subsequent Hbeta time lags for the nine objects where these measurements were possible. The Hbeta lag time is directly related to the size of the broad-line region, and by combining the lag time with the measured width of the Hbeta emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al. We also examine the time lag response as a function of velocity across the Hbeta line profile for six of the AGNs. The analysis of four leads to ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting broad-line region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on physical models of the BLR by the velocity-resolved response in these objects.
We present geometric and dynamical modeling of the broad line region for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The dataset includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H$beta$, C IV, and Ly$alpha$ broad emission lines. We find an extended disk-like H$beta$ BLR with a mixture of near-circular and outflowing gas trajectories, while the C IV and Ly$alpha$ BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C IV and Ly$alpha$ emission arising at smaller radii than the H$beta$ emission. Using the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of $log_{10}(M_{rm BH}/M_odot) = 7.64^{+0.21}_{-0.18}$. We examine the effect of using the $V$ band instead of the UV continuum light curve on the results and find a size difference that is consistent with the measured UV-optical time lag, but the other structural and kinematic parameters remain unchanged, suggesting that the $V$ band is a suitable proxy for the ionizing continuum when exploring the BLR structure and kinematics. Finally, we compare the H$beta$ results to similar models of data obtained in 2008 when the AGN was at a lower luminosity state. We find that the size of the emitting region increased during this time period, but the geometry and black hole mass remain unchanged, which confirms that the BLR kinematics suitably gauge the gravitational field of the central black hole.
Despite many decades of study, the kinematics of the broad-line region of 3C~273 are still poorly understood. We report a new, high signal-to-noise, reverberation mapping campaign carried out from November 2008 to March 2018 that allows the determination of time lags between emission lines and the variable continuum with high precision. The time lag of variations in H$beta$ relative to those of the 5100 Angstrom continuum is $146.8_{-12.1}^{+8.3}$ days in the rest frame, which agrees very well with the Paschen-$alpha$ region measured by the GRAVITY at The Very Large Telescope Interferometer. The time lag of the H$gamma$ emission line is found to be nearly the same as for H$beta$. The lag of the Fe II emission is $322.0_{-57.9}^{+55.5}$ days, longer by a factor of $sim$2 than that of the Balmer lines. The velocity-resolved lag measurements of the H$beta$ line show a complex structure which can be possibly explained by a rotation-dominated disk with some inflowing radial velocity in the H$beta$-emitting region. Taking the virial factor of $f_{rm BLR} = 1.3$, we derive a BH mass of $M_{bullet} = 4.1_{-0.4}^{+0.3} times 10^8 M_{odot}$ and an accretion rate of $9.3,L_{rm Edd},c^{-2}$ from the H$beta$ line. The decomposition of its $HST$ images yields a host stellar mass of $M_* = 10^{11.3 pm 0.7} M_odot$, and a ratio of $M_{bullet}/M_*approx 2.0times 10^{-3}$ in agreement with the Magorrian relation. In the near future, it is expected to compare the geometrically-thick BLR discovered by the GRAVITY in 3C 273 with its spatially-resolved torus in order to understand the potential connection between the BLR and the torus.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
