J/A+AS/132/181 Very luminous IRAS galaxies spectra. II. (Wu+ 1998)
A statistical study of the spectra of very luminous IRAS galaxies.
II. Spectral and environmental analysis
Wu H., Zou Z.L., Xia X.Y., Deng Z.G.
<Astron. Astrophys. Suppl. Ser. 132, 181 (1998)>
=1998A&AS..132..181W 1998A&AS..132..181W (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Infrared sources ; Spectroscopy
Keywords: infrared: galaxies - galaxies: active; starburst; interaction
Abstract:
Spectroscopic observations of a sample of 73 very luminous IRAS
galaxies (log(LIR/L☉)≥11.5 for H0=50km/s/Mpc, q0=0.5)
from the 2Jy redshift survey catalogue were carried out using the
2.16m telescope at the Beijing Astronomical Observatory. The
observational data, including the optical images (extracted from
Digital Sky Survey) and spectra for these galaxies, are presented in
paper I (Wu et al., 1998, Cat. J/A+AS/127/521). In this paper, we
give the spectral and morphological classifications for these very
luminous IRAS galaxies (VLIRGs). We show that about 60% of VLIRGs
exhibit AGN-like spectra (Seyfert 1s, Seyfert 2s, LINER-like
galaxies). This fraction goes up to 82% for the ultraluminous IRAS
galaxies (ULIRGs) subsample (Log(LIR/ L☉)≥12.0). 56% of the
VLIRGs show strong interaction or merging signatures; this fraction
rises to 91% for the ULIRGs. These statistical results strongly
suggest that interaction triggers nuclear activities and enhances the
infrared luminosity. We find that LINER and a mixture type which have
optical properties of both HII galaxies and LINERs could be at the
transition stage from infrared luminous HII galaxies to AGNs; their
main energy production is from starbursts as well as AGNs.
Both infrared luminosities and Ha equivalent widths increase
dramatically as nuclear separations between VLIRGs and their nearest
neighbors decrease. There is little doubt that strong starbursts
happen in the nuclei of VLIRGs. Assuming class 0 as advanced merger,
we construct a simple merger sequence, from morphological classes 1 to
4 (with near or far companions), to class 5 and 6 (interacting pairs
and mergers) and then to class 0 (isolated galaxies). Along this
sequence, VLIRGs evolve from HII galaxies to AGNs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 123 Reddenings, observed and dereddened line ratios
and spectral classification
table3.dat 71 123 Environmental and morphological parameters
tables.tex 206 592 LaTeX version of the tables
tables.ps 72 1295 PostSript version of the tables
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See also:
J/A+AS/127/521 : Very luminous IRAS galaxies spectra. I. (Wu+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- n_IRAS [(] Note on the source origin (1)
2- 11 A10 --- IRAS Source name
12 A1 --- m_IRAS Companion galaxies
14- 17 F4.2 mag E(B-V) Galactic extinction E(B-V)
19- 23 F5.2 --- Ha/Hb ? Observed Hα to Hβ ratio
24 A1 --- u_Ha/Hb [:;] Uncertainty flag on Ha/Hb (2)
26- 29 F4.2 mag E(B-V)o ? Color excess of VLIRGs from
observed Ha/Hb
30 A1 --- u_E(B-V)o [:;] Uncertainty flag on E(B-V)o (2)
32- 36 F5.2 --- log([OIII]/Hb) ? Logarithm of [OIII]5007/Hb
37 A1 --- u_log([OIII]/Hb) [:;] Uncertainty flag on
log([OIII]/Hb) (2)
39- 43 F5.2 --- log([OI]/Ha) ? Logarithm of [OI]6300/Ha
44 A1 --- u_log([OI]/Ha) [:;] Uncertainty flag on
log([OI]/Ha) (2)
46- 50 F5.2 --- log([NII]/Ha) ? Logarithm of [NII]6584/Ha
51 A1 --- u_log([NII]/Ha) [:;] Uncertainty flag on
log([NII]/Ha) (2)
53- 57 F5.2 --- log([SII]/Ha) ? Logarithm of [SII]6716+6731/Ha
58 A1 --- u_log([SII]/Ha) [:;] Uncertainty flag on
log([SII]/Ha) (2)
60- 63 F4.2 --- 6563/4861 Continuum color ratio at 6563A and 4861A
64 A1 --- u_6563/4861 [:;] Uncertainty flag on 6563/4861 (2)
66- 67 A2 --- SpType Spectral types (3)
69- 71 A3 --- Class Classification in Verons Catalog
(1993, Cat. VII/166) (4)
73- 76 F4.2 --- Ha/Hbth ? Theoretical Ha and Hb ratio
78- 82 F5.2 --- log([OIII]/Hb)0 ? Logarithm of dereddened [OIII]5007/Hb
83 A1 --- u_log([OIII]/Hb)0 [:;] Uncertainty flag on
log([OIII]/Hb)0 (2)
85- 89 F5.2 --- log([OI]/Ha)0 ? Logarithm of dereddened [OI]6300/Ha
90 A1 --- u_log([OI]/Ha)0 [:;] Uncertainty flag on
log([OI]/Ha)0 (2)
92- 96 F5.2 --- log([NII]/Ha)0 ? Logarithm of dereddened [NII]6584/Ha
97 A1 --- u_log([NII]/Ha)0 [:;] Uncertainty flag on
log([NII]/Ha)0 (2)
99-103 F5.2 --- log([SII]/Ha)0 ? Logarithm of dereddened
[SII]6716+6731/Ha
104 A1 --- u_log([SII]/Ha)0 [:;] Uncertainty flag on
log([SII]/Ha)0 (2)
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Note (1): A bracket indicates the sources that not belong to the 73
complete sample
Note (2): The uncertainty is about 15%.
(:): mean uncertainties 30%
(;): mean uncertainties 50%
Note (3): S1: Seyfert 1
S2: Seyfert 2
L: LINER
H: HII galaxy
LH: mixture type with properties of both LINER and HII galaxy
S?: Seyfert 2 or LINER
Note (4): Classification in Verons (1993, Cat. VII/166):
S1: Seyfert 1
S2: Seyfert 2
H2: HII galaxy
S or S?: Could be Seyfert or LINER.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- n_IRAS [(] Note on source origin (1)
2- 11 A10 --- IRAS Source name
12 A1 --- m_IRAS Companion galaxies
14- 20 F7.2 Mpc Dist Distance of VLIRGs (H0=50km/s/Mpc,q0=0.5)
22 I1 --- MType ? Morphological types (2)
24- 29 F6.2 kpc Sep ? Projected separation between the nearest companions
31- 36 F6.4 --- Dz ? Redshift difference of the nearest companion
39- 71 A33 --- --- Comments
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Note (1): A bracket indicates the sources that not belong to the 73
complete sample
Note (2): Morphological classification (Lawrence et al., 1989MNRAS.240..329L 1989MNRAS.240..329L)
0: isolated
1: distant faint companion
2: distant bright companion
3: near faint companion
4: near bright companion
5: interacting pair
6: merger or highly peculiar
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Acknowledgements: Hong Wu
(End) Patricia Bauer [CDS] 03-Apr-1998