J/ApJS/222/25 Long-term optical monitoring of E1821+643 (Shapovalova+, 2016)
First long-term optical spectral monitoring of a binary black hole candidate
E1821+643.
I. Variability of spectral lines and continuum.
Shapovalova A.I., Popovic L.C., Chavushyan V.H., Burenkov A.N., Ilic D.,
Kollatschny W., Kovacevic A., Valdes J.R., Patino-Alvarez V.,
Leon-Tavares J., Torrealba J., Zhdanova V.E.
<Astrophys. J. Suppl. Ser., 222, 25 (2016)>
=2016ApJS..222...25S 2016ApJS..222...25S (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Line Profiles ; Spectroscopy ; Photometry, UBVRI
Keywords: galaxies: active; line: profiles; quasars: emission lines;
quasars: (QSO E1821+643); galaxies: active; line: profiles;
quasars: emission lines quasars: (QSO E1821+643)
Abstract:
We report the results of the first long-term (1990-2014) optical
spectrophotometric monitoring of a binary black hole candidate
QSO E1821+643, a low-redshift, high-luminosity, radio-quiet quasar. In
the monitored period, the continua and Hγ fluxes changed about
two times, while the Hβ flux changed about 1.4 times. We found
periodical variations in the photometric flux with periods of 1200,
1850, and 4000 days, and 4500-day periodicity in the spectroscopic
variations. However, the periodicity of 4000-4500 days covers only one
cycle of variation and should be confirmed with a longer monitoring
campaign. There is an indication of the period around 1300 days in the
spectroscopic light curves, but with small significance level, while
the 1850-day period could not be clearly identified in the
spectroscopic light curves. The line profiles have not significantly
changed, showing an important red asymmetry and broad line peak
redshifted around +1000km/s. However, Hβ shows a broader mean
profile and has a larger time lag (τ∼120 days) than Hγ
(τ∼60 days). We estimate that the mass of the black hole is
∼2.6x109M☉. The obtained results are discussed in the frame of
the binary black hole hypothesis. To explain the periodicity in the
flux variability and high redshift of the broad lines, we discuss a
scenario where dense, gas-rich, cloudy-like structures are orbiting
around a recoiling black hole.
Description:
The photometry in BVR filters of E1821+643 was performed at the
Special Astrophysical Observatory of the Russian Academy of Science
(SAO RAS) during the 2003-2014 period (98 nights) with the 1m Zeiss
telescope. The photometric system of this instrument resembles those
of Johnson in the B and V filters and of Cousins in the R filter.
Spectra of E1821+643 (∼140 nights) were acquired with two telescopes
(6m and 1m) at SAO RAS, Russia (during 1998-2014), one telescope
(INAOE's 2.1m) at Guillermo Haro Observatory (GHO) Cananea, Sonora,
Mexico (during 1998-2007 and 2013), and two telescopes (3.5m and 2.2m)
at Calar Alto Observatory, Spain (during 1990-1994).
Objects:
--------------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------------
18 21 57.24 +64 20 36.2 E1821+643 = QSO B1821+6419
--------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 64 98 The measured photometric magnitudes
table3.dat 56 127 Log of spectroscopic observations
table5.dat 65 127 Measured line and continuum fluxes
table7.dat 73 127 Measured broad-line and line-segment fluxes
of Hβ
--------------------------------------------------------------------------------
See also:
J/A+A/583/A75 : Large Quasar Astrometric Catalogue 3 (LQAC-3) (Souchay+, 2015)
J/A+A/573/A101 : Generalised Lomb-Scargle periodogram code (Mortier+, 2015)
J/MNRAS/445/2061 : Absorption in circumgalactic medium (Liang+, 2014)
J/A+A/559/A10 : Arp 102B spectral optical monitoring (Shapovalova+, 2013)
J/ApJS/189/15 : FeII emission in a sample of AGN spectra (Kovacevic+, 2010)
J/ApJ/716/993 : LAMP: reverberation mapping of H and He lines (Bentz+, 2010)
J/ApJ/702/1353 : Hβ and V-band light curves of NGC 4051 (Denney+, 2009)
J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)
J/AJ/138/845 : BVRI observations of 235 bright quasars (Ojha+, 2009)
J/A+A/422/925 : Profile variability in lines of NGC 5548 (Shapovalova+ 2004)
J/A+A/412/707 : Absorption-line systems in QSO spectra (Ryabinkov+, 2003)
J/ApJS/143/257 : AGN emission line properties (Kuraszkiewicz+, 2002)
J/A+A/376/775 : UBVRI and H-beta observations of 3C 390.3 (Shapovalova+ 2001)
J/ApJS/97/1 : HST Quasar Absorption Line Key Project. X. (Lockman+ 1995)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Photometric Observation Running Number
4- 13 A10 "D/M/Y" Date UT observation date
15- 21 F7.1 d JD Modified Julian Date, JD-2400000
23- 25 F3.1 arcsec Seeing [1/4.1] Mean Photometric Observation Seeing
27- 32 F6.3 mag Rmag [13.4/14]? R band magnitude
34- 38 F5.3 mag e_Rmag [0.009/0.04]? Uncertainty in Rmag
40- 45 F6.3 mag Vmag [14.6/15.3] V band magnitude
47- 51 F5.3 mag e_Vmag [0.008/0.04] Uncertainty in Vmag
53- 58 F6.3 mag Bmag [13.7/14.6] B band magnitude
60- 64 F5.3 mag e_Bmag [0.009/0.04] Uncertainty in Bmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Spectroscopic Observation Running Number
5- 14 A10 "D/M/Y" Date UT observation date
16- 22 F7.1 d JD Modified Julian Date, JD-2400000
24- 28 A5 --- Code Spectroscopic Observation Code (1)
30- 32 F3.1 arcsec ApX Projected spectrograph entrance aperture in X
34- 38 F5.2 arcsec ApY Projected spectrograph entrance aperture in Y
40- 43 I4 0.1nm Spmin [3700/6060] Spectral Range, minimum in Angstroms
45- 48 I4 0.1nm Spmax [6630/7690] Spectral Range, maximum in Angstroms
50- 52 F3.1 arcsec Seeing [1/5.5]? Mean Spectroscopic Observation Seeing
54- 56 F3.1 arcsec B_Seeing [2.5]? Spectroscopic Observation Seeing, Maximum
--------------------------------------------------------------------------------
Note (1): Spectroscopic Observation Code (from Table 2) as follows:
L(N) = SAO (Russia), 6m + Long slit Nasmith
L(U) = SAO (Russia), 6m + UAGS Prime
L(Sc) = SAO (Russia), 6m + Scorpio Prime
GHO = Guillermo Haro Obs (Mexico), 2.1m + B&C Cassegrain
Z1 = SAO (Russia), 1m + GAD Cassegrain
Z2K = SAO (Russia), 1m + GAD Cassegrain
CA1 = Calar Alto (Spain), 3.5m + B&C/TWIN Cassegrain
CA2 = Calar Alto (Spain), 2.2m + B&C Cassegrain
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Spectroscopic Observation Running Number
5- 14 A10 "D/M/Y" Date UT observation date
16- 22 F7.1 d JD Modified Julian Date, JD-2400000
24- 28 F5.2 10-17W/m2/nm F(5100) [4.9/10.7] Continuum flux at 5100Å,
rest frame, in 10-15erg/cm2/s/A
30- 33 F4.2 10-17W/m2/nm e_F(5100) [0.1/0.3] Uncertainty in F(5100),
in 10-15erg/cm2/s/A
35- 39 F5.2 10-16W/m2 Hbeta [10.8/15.2] Hβ line flux,
in 10-13erg/cm2/s
41- 44 F4.2 10-16W/m2 e_Hbeta [0.3/0.5] Uncertainty in Hbeta,
in 10-13erg/cm2/s
46- 50 F5.2 10-17W/m2/nm F(4200) [6.5/14]? Continuum flux at 4200Å,
rest frame, in 10-15 erg/cm2/s/A
52- 55 F4.2 10-17W/m2/nm e_F(4200) [0.2/0.5]? Uncertainty in F(4200),
in 10-15 erg/cm2/s/A
57- 60 F4.2 10-16W/m2 Hgamma [1.9/4.2]? Hγ line flux,
in 10-13erg/cm2/s
62- 65 F4.2 10-16W/m2 e_Hgamma [0.1/0.3]? Uncertainty in Hgamma,
in 10-13erg/cm2/s
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Spectroscopic Observation Running Number
5- 11 F7.1 d JD Modified Julian Date, JD-2400000
14- 19 F6.3 10-13mW/m2 Hb-broad [6.4/11.3] Flux of broad Hβ,
total line
21- 25 F5.3 10-13mW/m2 e_Hb-broad [0.1/0.4] Uncertainty in Hb-broad
27- 31 F5.3 10-13mW/m2 Hb-blue [0.6/1.2] Flux of broad Hβ
line-segments, blue
33- 37 F5.3 10-13mW/m2 e_Hb-blue Uncertainty in Hb-blue
39- 43 F5.3 10-13mW/m2 Hb-core [3.2/5.9] Flux of broad Hβ
line-segments, core
45- 49 F5.3 10-13mW/m2 e_Hb-core Uncertainty in Hb-core
51- 55 F5.3 10-13mW/m2 Hb-red [1.5/3] Flux of broad Hβ
line-segments, red
57- 61 F5.3 10-13mW/m2 e_Hb-red Uncertainty in Hb-red
63- 67 F5.3 10-13mW/m2 Hb-far [0.5/1.2] Flux of broad Hβ
line-segments, far red
69- 73 F5.3 10-13mW/m2 e_Hb-far Uncertainty in Hb-far
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Mar-2016