J/ApJ/827/118 A new reverberation mapping campaign on NGC 5548 (Lu+, 2016)
Reverberation mapping of the broad-line region in NGC 5548: evidence for
radiation pressure?
Lu K.-X., Du P., Hu C., Li Y.-R., Zhang Z.-X., Wang K., Huang Y.-K.,
Bi S.-L., Bai J.-M., Ho L.C., Wang J.-M.
<Astrophys. J., 827, 118-118 (2016)>
=2016ApJ...827..118L 2016ApJ...827..118L (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Spectroscopy ; Velocity dispersion ;
Photometry
Keywords: galaxies: active; galaxies: individual: NGC 5548; galaxies: nuclei
Abstract:
NGC 5548 is the best-observed reverberation-mapped active galactic
nucleus with long-term, intensive monitoring. Here we report results
from a new observational campaign between 2015 January and July. We
measure the centroid time lag of the broad Hβ emission line with
respect to the 5100Å continuum and obtain
τcent=7.20-0.35+1.33days in the rest frame. This yields a
black hole mass of M.=8.71-2.61+3.21x107M☉ using a broad
Hβ line dispersion of 3124±302km/s and a virial factor of
fBLR=6.3±1.5 for the broad-line region (BLR), consistent with the
mass measurements from previous Hβ campaigns. The high-quality
data allow us to construct a velocity-binned delay map for the broad
Hβ line, which shows a symmetric response pattern around the line
center, a plausible kinematic signature of virialized motion of the
BLR. Combining all the available measurements of Hβ time lags and
the associated mean 5100Å luminosities over 18 campaigns between
1989 and 2015, we find that the Hβ BLR size varies with the mean
optical luminosity, but, interestingly, with a possible delay of
2.35-1.25+3.47 years. This delay coincides with the typical BLR
dynamical timescale of NGC 5548, indicating that the BLR undergoes
dynamical changes, possibly driven by radiation pressure.
Description:
The spectroscopic and photometric observations of NGC 5548 were made
using the Yunnan Faint Object Spectrograph and Camera (YFOSC), mounted
on the Lijiang 2.4m telescope at Yunnan Observatory, Chinese Academy
of Sciences. Our observations started on 2015 January 7, and ended on
2015 July 11. We used Grism 14, which provides a resolution of
92Å/mm (1.8Å/pixel) and covers the wavelength range 3800-7200Å.
To verify the calibration of the spectroscopic data, we also made
photometric observations using a Johnson V filter. We took three
consecutive exposures of 90s each. In total, we obtained 62
spectroscopic observations and 61 photometric observations, spanning a
time period of 180 days.
Objects:
-------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------
14 17 59.51 +25 08 12.5 NGC 5548 = UGC 9149
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 62 Continuum and Hβ fluxes for NGC 5548
table4.dat 138 18 All the RM measurements of NGC 5548
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See also:
J/ApJS/225/29 : NGC 5548 43 year-long monitoring in Hβ (Bon+, 2016)
J/ApJ/825/126 : SEAMBHs. V. The third year (Du+, 2016)
J/ApJ/821/56 : Space telescope RM project III. NGC 5548 LC (Fausnaugh+, 2016)
J/ApJ/806/129 : Space telescope RM project II. Swift data (Edelson+, 2015)
J/ApJ/806/128 : Space telescope RM project I. NGC5548 (De Rosa+, 2015)
J/ApJ/806/22 : SEAMBHs IV. Hβ time lags (Du+, 2015)
J/ApJ/782/45 : SEAMBHs. I. Mrk 142, Mrk 335, and IRAS F12397+3333 (Du+, 2014)
J/ApJ/779/109 : Long-term monitoring of NGC 5548 (Peterson+, 2013)
J/ApJ/702/1353 : Hβ and V-band light curves of NGC 4051 (Denney+, 2009)
J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)
J/A+A/422/925 : Profile variability in lines of NGC 5548 (Shapovalova+ 2004)
J/A+A/371/79 : NGC 5548 UBVRI phot. & Halpha, Hbeta fluxes (Dietrich+, 2001)
J/ApJ/510/659 : Size and Structure of AGN in NGC 5548 (Peterson+, 1999)
J/A+A/314/43 : NGC 5548 Profile variability (Kollatschny+ 1996)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 d JD1 Spectroscopic (F5100, Hβ)
observation date; JD-2450000
9- 12 F4.2 10-17W/m2/nm F5100 [2.7/6.5] 5100A continuum spectroscopic
flux; 10-15erg/s/cm2^/Angstrom
14- 17 F4.2 10-17W/m2/nm e_F5100 [0.2/0.5] Uncertainty in F5100
19- 22 F4.2 10-16W/m2 FHb [5.6/8.7] Hβ spectroscopic flux;
10-13erg/s/cm2^
24- 27 F4.2 10-16W/m2 e_FHb [0.2/0.4] Uncertainty in FHb
29- 35 F7.2 d JD2 ? Photometric (V-band) observation date;
JD-2450000
37- 40 F4.2 mag Vmag [1.3/1.7]? Johnson V-band; instrumental
magnitude, arbitrary zeropoint
42- 45 F4.2 mag e_Vmag [0.01/0.08]? Uncertainty in Vmag
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [Year]
6- 7 I2 --- Yr Data set year number
9- 16 A8 "Y/M" Date1 UT date of starting observations
17 A1 --- --- [-]
18- 25 A8 "Y/M" Date2 UT date of ending observations
27- 33 F7.2 yr T Observation time in decimal years
35- 39 F5.3 --- Fvar [0.1/0.5]? Variability amplitude (1)
41- 45 F5.2 [10-7W] logL5100 [42.5/43.6] Log of 5100Å luminosity
47- 50 F4.2 [10-7W] e_logL5100 [0.08/0.2] logL5100 uncertainty
52- 56 F5.2 [10-7W] logLHb [41/42]? Log of Hβ luminosity
58- 61 F4.2 [10-7W] e_logLHb [0.03/0.1]? logLHb uncertainty
63- 67 F5.2 d Hblag [4/27] Hβ lag
69- 72 F4.2 d e_Hblag [0.3/7.3] Negative uncertainty on Hblag
74- 77 F4.2 d E_Hblag [0.6/6] Positive uncertainty on Hblag
79- 83 I5 km/s FWHM [4674/12771]? Full width half maximum of
Hβ line from mean spectra
85- 87 I3 km/s e_FWHM [36/574]? FWHM uncertainty
89- 92 I4 km/s Sig [1934/4266]? Dispersion velocity of
Hβ line from mean spectra
94- 96 I3 km/s e_Sig [5/642]? Sig uncertainty
98-102 I5 km/s FWHM2 [4044/11177]? Full width half maximum of
Hβ line from rms spectra
104-107 I4 km/s e_FWHM2 [112/2266]? FWHM2 uncertainty
109-112 I4 km/s Sig2 [1687/4270]? Dispersion velocity of
Hβ line from rms spectra
114-116 I3 km/s e_Sig2 [30/768]? Sig2 uncertainty
118-121 F4.2 [Msun] logM [7.4/8.2]? BH mass (logM{dot}) (2)
123-126 F4.2 [Msun] e_logM [0.1/0.3]? Negative uncertainty on logM
128-131 F4.2 [Msun] E_logM [0.1/0.4]? Positive uncertainty on logM
133-137 A5 --- Ref Reference(s) (3)
138 A1 --- f_Ref Flag on Ref (4)
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Note (1): Following standard practice (e.g.,
Rodriguez-Pascual+ 1997ApJS..110....9R 1997ApJS..110....9R), we calculate the variability
amplitude of the light curves of the 5100Å continuum and
Hβ emission line using Equation (1):
Fvar=(σ2-Δ2)0.5/
where =N-1Σi=1NFi is the average flux, Fi is the
flux of the ith observation of the light curve, N is the total number
of observations, σ2=Σi=1N(Fi-)2/(N-1),
Δ2=Σi=1NΔi2/N, and Δi is the
uncertainty of Fi. See section 3.1 for further explanations.
Note (2): M{dot} is calculated from the line dispersion of the rms spectrum
with a virial factor of fBLR=6.3±1.5
(Ho & Kim 2014ApJ...789...17H 2014ApJ...789...17H). These campaigns yield a mean BH mass
of <M{dot}> =8.39±0.72x107M☉.
Note (3): References as follows:
1 = Kilerci Eser et al. (2015ApJ...801....8K 2015ApJ...801....8K),
2 = Collin et al. (2006A&A...456...75C 2006A&A...456...75C),
3 = Peterson et al. (2004, J/ApJ/613/682),
4 = Bentz et al. (2007ApJ...662..205B 2007ApJ...662..205B),
5 = Denney et al. (2010ApJ...721..715D 2010ApJ...721..715D),
6 = Bentz et al. (2010ApJ...720L..46B 2010ApJ...720L..46B),
7 = Fausnaugh et al. (2016, J/ApJ/821/56),
8 = This work.
Note (4): Flag as follows:
a = "Year 12" is compiled from the 12th RM observation in the AGN Watch
project (Peterson+ 2002ApJ...581..197P 2002ApJ...581..197P). The cross-correlation analysis is
very ambiguous (see Figure 2 of Peterson+ 2002ApJ...581..197P 2002ApJ...581..197P), and we
excluded this data set in our analysis.
b = Pancoast+ (2014MNRAS.445.3073P 2014MNRAS.445.3073P) modeled the data and provided the
model-dependent Hβ lag of 3.22-0.54+0.66days, which is consistent
(within the uncertainties) with 4.17-1.33+0.90days determined by the
cross correlation analysis in Bentz+ (2010ApJ...720L..46B 2010ApJ...720L..46B). We use the
Hβ lag of Bentz+ (2010ApJ...720L..46B 2010ApJ...720L..46B) for consistency.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Nov-2016