J/A+A/552/A135 Activity of the Seyfert galaxy neighbours (Koulouridis, 2013)
Activity of the Seyfert galaxy neighbours.
Koulouridis E., Plionis M., Chavushyan V., Dultzin D., Krongold Y.,
Georgantopoulos I., Leon-Tavares J.
<Astron. Astrophys. 552, A135 (2013)>
=2013A&A...552A.135K 2013A&A...552A.135K
ADC_Keywords: Active gal. nuclei ; Galaxies, Seyfert ; Galaxies, spectra ;
Equivalent widths
Keywords: galaxies: active - galaxies: Seyfert - galaxies: interactions -
galaxies: nuclei - large-scale structure of Universe -
X-rays: galaxies
Abstract :
We present a follow-up study of a series of papers concerning the role
of close interactions as a possible triggering mechanism of AGN
activity. We have already studied the close (<100kpc/h) and the
large-scale (<1Mpc/h) environment of a local sample of Sy1, Sy2, and
bright IRAS galaxies (BIRG) and of their respective control samples.
The results led us to the conclusion that a close encounter appears
capable of activating a sequence where an absorption line galaxy (ALG)
galaxy first becomes a starburst, then a Sy2, and finally a Sy1. Here
we investigate the activity of neighbouring galaxies of different
types of AGN, since both galaxies of an interacting pair should be
affected. To this end we present the optical spectroscopy and X-ray
imaging of 30 neighbouring galaxies around two local (z<0.034) samples
of 10 Sy1 and 13 Sy2 galaxies. Although this is a pilot study of a
small sample, various interesting trends have been discovered that
imply physical mechanisms that may lead to different Seyfert types.
Based on the optical spectroscopy we find that more than 70% of all
neighbouring galaxies exhibit star forming and/or nuclear activity
(namely recent star formation and/or AGN), while an additional X-ray
analysis showed that this percentage might be significantly higher.
Furthermore, we find a statistically significant correlation, at a
99.9% level, between the value of the neighbour's [OIII]/Hβ ratio
and the activity type of the central active galaxy, i.e. the
neighbours of Sy2 galaxies are systematically more ionized than the
neighbours of Sy1s. This result, in combination with trends found
using the Equivalent Width of the Hα emission line and the
stellar population synthesis code STARLIGHT, indicate differences in
the stellar mass, metallicity, and star formation history between the
samples. Our results point towards a link between close galaxy
interactions and activity and also provide more clues regarding the
possible evolutionary sequence inferred by our previous studies.
Description:
Spectra and spectral classification of all Seyfert galaxy neighbours.
Optical spectra were taken with the Boller & Chivens spectrograph
mounted on the 2.1m telescope at the Observatorio Astronomico Nacional
in San Pedro Martir (OAN-SPM). Observations were carried out during
photometric conditions. All spectra were obtained with a 2.5" slit.
The typical wavelength range was 4000-8000Å and the spectral
resolution R=8Å. Spectrophotometric standard stars were observed
every night.
The data reduction was carried out with the IRAF package following a
standard procedure. Spectra were bias-subtracted and corrected with
dome flat-field frames. Arc-lamp (CuHeNeAr) exposures were used for
wavelength calibration. We disentangled the spectral contribution of
the host galaxy from the observed spectra by using the stellar
population synthesis code STARLIGHT.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 30 Spectral properties
sp/* 18 19 Sub-directory with spectra of emission-line galaxies
(ELG nuclei) from SPM (San Pedro Martir observatory)
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See also:
II/306 : SDSS Photometric Catalog, Release 8 (Adelman-McCarthy+, 2011)
VII/173 : Catalogue of Seyfert Galaxies (Lipovetsky+, 1988)
J/ApJS/98/477 : Optical spectral atlas of Seyfert nuclei (Ho+ 1995)
J/A+A/366/771 : The Hamburg/SAO Survey for ELGs. IV (Kniazev+, 2001)
J/ApJS/145/199 : Opt. spectroscopic atlas of low-redshift AGN (Marziani+ 2003)
J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+ 2004)
J/AJ/130/2571 : KISS Hα-selected survey list 3 (Jangren+, 2005)
J/ApJ/639/37 : AGN Seyfert galaxies and close neighbors (Koulouridis+, 2006)
J/ApJS/166/498 : Atlas of HST STIS spectra of Seyfert (Spinelli+, 2006)
J/MNRAS/366/480 : Emission-line properties of Seyfert 2 nuclei (Gu+, 2006)
J/ApJ/660/1072 : Unified model of active galactic nuclei (Wang+, 2007)
J/ApJ/713/L11 : X-ray properties of Seyfert 1 galaxies (Zhou+, 2010)
J/ApJ/737/71 : The [OIII] emission line in SDSS AGN (Zhang+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Name Name in Tables 1 and 2 of Koulouridis et al.,
Cat. J/ApJ/639/37 (Galaxy_N[1/4]A)
20- 22 A3 --- Type Seyfert Type of the central AGN (Sy1 or Sy2)
24- 25 I2 h RAh Hour of right ascension (J2000)
27- 28 I2 min RAm Minute of right ascension (J2000)
30- 33 F4.1 s RAs Second of right ascension (J2000)
35 A1 --- DE- Declination sign
36- 37 I2 deg DEd Degree of declination (J2000)
39- 40 I2 arcmin DEm Arcminute of declination (J2000)
42- 43 I2 arcsec DEs Arcsecond of declination (J2000)
45- 48 A4 --- obs [SDSS/SPM ] Sloan (SDSS) / San Pedro Martir (SPM)
50- 53 F4.2 --- R1 ?=9.99 Ratio of [OIII]/Hβ
55- 58 F4.2 --- e_R1 ?=9.99 Error of the [OIII]/Hβ ratio
60- 63 F4.2 --- R2 ?=9.99 Ratio of [NII]/Hα
65- 68 F4.2 --- e_R2 ?=9.99 Error of the [NII]/Hα ratio
70- 73 F4.2 --- R3 ?=9.99 Ratio of [SII]/Hα
75- 78 F4.2 --- e_R3 ?=9.99 Error of the [SII]/Hα ratio
80- 83 F4.1 0.1nm EW [1.2/72.5]?=99.9 Equivalent Width of the
Hα (absolute value, in Å)
85- 87 F3.1 0.1nm e_EW ?=9.9 Error of the EW
89- 91 A3 --- SPT BPT Spectral classification of the neighbour (1)
93-104 A12 --- Sp ELG nuclei spectrum as an ASCII file in sp
subdirectory (2)
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Note (1): Classification as follows:
ALG = Absorption line galaxy
SFN = Star-forming nuclei
AGN = Active galactic nuclei
TO = Transition object
NO = No classification based on the BPT diagram (1981PASP...93....5B 1981PASP...93....5B)
Note (2): Stellar background not subtracted. SDSS spectra can be found
in the SDSS database.
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 9 F9.3 0.1nm lambda [3200/6900] Wavelength λ (Å)
11- 18 F8.3 --- Flux [0/1972.57] Flux density, in arbitrary units
of energy per wavelength interval
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Acknowledgements:
E. Koulouridis, ekoulour(at)astro.noa.gr
(End) E. Koulouridis [IAASARS, Nat. Obsorvatory Of Athens] 17-Feb-2013