J/AJ/121/97 K-band spectroscopy of ULIRGs (Murphy+, 2001)
K-band spectroscopy of ultraluminous infrared galaxies: the 2 Jy sample.
Murphy T.W.JR, Soifer B.T., Matthews K., Armus L., Kiger J.R.
<Astron. J., 121, 97-127 (2001)>
=2001AJ....121...97M 2001AJ....121...97M
ADC_Keywords: Galaxies, IR ; Galaxies, spectra
Keywords: Galaxies: Active, Galaxies: Starburst
Abstract:
We present near-infrared spectroscopy for a complete sample of 33
ultraluminous infrared galaxies at a resolution of R∼1000. Most of the
wavelength range from 1.80-2.20µm in the rest frame is covered,
including the Paα and Brγ hydrogen recombination lines,
and the molecular hydrogen vibration-rotation 1-0 S(1) and S(3) lines.
Other species, such as He I, [Fe II], and [Si VI] appear in the
spectra as well, in addition to a number of weaker molecular hydrogen
lines. Nuclear extractions for each of the individual galaxies are
presented here, along with spectra of secondary nuclei, where
available. The Paα emission is seen to be highly concentrated on
the nuclei, typically with very little emission extending beyond a
radius of 1kpc.
This survey was carried out primarily to search for signatures of
active nuclei via velocity-broadened hydrogen recombination or the
presence of the [Si VI] coronal line. These signatures are rare in
the present sample, occurring in only two of the 33 galaxies. The
extinction to the hydrogen recombination lines is investigated via the
Paα/Brγ line ratio. It is found that visual extinctions to
the nuclei in excess of 10mag are relatively common among ULIRGs and
that visual extinctions greater than 25mag are necessary to conceal a
QSO emitting half the total bolometric luminosity. The ionized
hydrogen regions in many ULIRGs are sufficiently obscured that
dust-enshrouded active galactic nuclei would remain hidden at 2µm
at the current level of sensitivity. The vibration-rotation lines of
molecular hydrogen appear to be predominantly thermal in origin, with
effective temperatures generally around 2200K. The relative nuclear
velocities between double nucleus ULIRGs are investigated, through
which it is inferred that the maximum deprojected velocity difference
is ∼200km.s-1. This figure is lower than the velocities predicted by
physical models of strong interactions/mergers of large, gas-rich
galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 37 33 Spectroscopic Survey Sample
table5.dat 57 33 Derived Properties
table6.dat 30 12 Relative Nuclear Radial Velocities
table7.dat 29 15 Physical Parameters of H2 Transitions
table8.dat 40 15 Expected H2 Line Strengths
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Galaxy Name
17- 18 A2 --- n_Name Note (1)
20- 24 I5 km/s cz Galaxy redshift
26- 30 F5.2 [solLum] LumIR IR luminosity in solar units
32- 35 F4.1 arcsec Sep ? Separation of nuclei
37 A1 --- n_Sep [SD] Nucleus structure (2)
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Note (1):
b = Galaxies with ``warm'' infrared colors:
Fν(25um)/Fν(60um) > 0.2;
c = Contained in the Bright Galaxy Sample (BGS) of
Soifer et al. 1987 (1987ApJ...320..238S 1987ApJ...320..238S).
Note (2):
S = Denotes a single nucleus;
D = Denotes a double nucleus system for which only the primary nucleus
spectrum is presented, generally because the separation exceeds the
slit length.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Galaxy name
17- 21 F5.1 mag Av Extinction based on Paα/Brγ
23- 26 F4.1 mag e_Av Uncertainty in Av
28 A1 --- f_Av [d] Indicates apertures for the Paα &
Brγ spectral extractions differ by
at least 50%
30 A1 --- l_Trot Limit flag on Trot
31- 34 I4 K Trot H2 line rotational temperature
36- 38 I3 K e_Trot ? Uncertainty in Trot
40- 43 I4 K Tvib ? H2 line vibrational temperature (1)
45- 48 I4 K e_Tvib ? Uncertainty in Tvib
50- 57 A8 --- Mech H2 excitation Mechanism (2)
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Note (1): Given only for definite thermal/fluorescent mixtures and for
likely mixtures (when both of the observed 2-1 lines are above the
rotation temperature prediction). The vibration temperature assumes
an ortho-to-para ratio of 2:1 in the 2-1 transition states.
Note (2):
thermal = Classified as consistent with purely thermal;
mixture = Classified as definite mixture of thermal and fluorescence;
thermal* = Classified as possible mixture of thermal and fluorescence.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 15 A15 ---- Name Galaxy name
17- 20 I4 km/s Vel Relative velocity
22- 23 I2 km/s e_Vel Uncertainty in Vel
25 A1 --- f_Vel Flag on Vel (1)
27- 30 F4.1 kpc Sep Projected separation
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Note (1): From Murphy et al. 2000b (2000AJ....120.1675M 2000AJ....120.1675M). The current data
set yields -22±169.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Trans H2 transition
10- 16 F7.5 um Wave Wavelength in air
18 I1 --- J1 The J1 rotation state
20- 23 F4.2 10-7/s Prob Transition probability from Turner,
Kirby-Docken, & Dalgarno 1977
25- 29 I5 K E1/k Energy divided by the Boltzmann constant
from Dabrowski 1984
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Trans H2 transition (1)
10- 16 F7.5 um Wave Wavelength in air
18- 22 F5.3 --- S15 H2 line strength relative to H2 1-0 S(1)
at Trot=1500 K
24- 28 F5.3 --- S20 H2 line strength relative to H2 1-0 S(1)
at Trot=2000 K
30- 34 F5.3 --- S25 H2 line strength relative to H2 1-0 S(1)
at Trot=2500 K
36- 40 F5.3 --- S40 H2 line strength relative to H2 1-0 S(1)
at Trot=4000 K
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Note (1): This table assumes that T{rot}=0.8T{vib}. To recover a
strictly thermal regime (T{rot}=T{vib}=T), multiply the 2-1
transitions by exp(-1107/T) and the 3-2 transition by exp(-2144/T).
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History:
From electronic version of the journal
* 08-May-2005: IRAS 14352-1954 has been corrected into IRAS 14351-1954
(End) Greg Schwarz [AAS], Laurent Cambresy [CDS] 22-Jul-2004