J/A+A/581/A33 Nearby radio galaxies FUV to MIR properties (De Ruiter+, 2015)
Far-UV to mid-IR properties of nearby radio galaxies.
De Ruiter H.R., Parma P., Fanti R., Fanti C.
<Astron. Astrophys., 581, A33-33 (2015)>
=2015A&A...581A..33D 2015A&A...581A..33D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Galaxies, radio ; Photometry, ultraviolet ;
Photometry, SDSS ; Photometry, infrared
Keywords: galaxies: active - galaxies: photometry - radio continuum: galaxies -
ultraviolet: galaxies
Abstract:
We investigate whether the far-UV continuum of nearby radio galaxies
is due solely to the parent galaxy that passively evolves, or if it
reveals evidence for the presence of other star-forming or non-stellar
components. If the UV excess is due to an additional radiation
component, we compare this with other properties such as radio power,
optical spectral type (e.g. high- and low-excitation galaxies), and
the strength of the emission lines. We also discuss the possible
correlation between the ultraviolet flux, IR properties, and the
central black hole mass. We used a sample of low-luminosity B2 radio
galaxies and a small sample of higher luminosity 3C radio galaxies at
comparable redshift (z<0.2). Spectral energy distributions (SEDs) were
constructed using a number of on-line databases that are freely
available now: GALEX, SDSS, 2MASS, and WISE. These were compared with
model SEDs of early-type galaxies with passively evolving stellar
populations at various ages (typically 0.5-1.3x109 years). We
established whether a second component was needed to obtain a
satisfactory fit with the observed overall SED. We introduce the
parameter XUV, which measures the excess slope of the UV continuum
between 4500 and 2000Å with respect to the UV radiation produced by
the underlying old galaxy component. We find that the UV excess as
measured by XUV is usually small or absent in low-luminosity (FR I)
sources, but sets in abruptly at the transition radio power, above
which we find mostly FRII sources. XUV behaves very similarly to the
strength of the optical emission lines (in particular Hα). Below
P1.4GHz<1024W/Hz XUV is close to zero. XUV correlates strongly
with the Hα line strength, but only in sources with strong
Hα emission. We discuss whether the line emission might be due
to photoionization by radiation from the parent galaxy, possibly with
additional star formation, or if it requires the presence of a
non-stellar active galactic nucleus component. XUV and the slope of
the mid-IR are strongly correlated, as measured by the WISE bands in
the interval 3.4 to 22µm, in the sense that sources with a strong
UV excess also have stronger IR emission. There is an inverse
correlation between XUV and central black hole mass: the MBH of
objects with strong UV excess is on average two to three times less
massive than that of objects without UV excess. Low-luminosity radio
galaxies tend to be more massive and contain more massive black holes.
Description:
As the basis for our analysis, we selected two samples of low-redshift
(z<0.2) radio galaxies in the area covered by the SDSS: first, B2
radio galaxies (Fanti et al., 1987A&AS...69...57F 1987A&AS...69...57F; de Ruiter et al.,
1990A&A...227..351D 1990A&A...227..351D). They are mostly low-luminosity FR I sources
identified with early-type galaxies. Second, a sample extracted from
the 3CR catalogue (Laing et al., 1962MNRAS.125...75B 1962MNRAS.125...75B).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 56 78 WISE magnitudes of B2 and 3C radio galaxies
table3.dat 97 82 GALEX, SDSS, and 2MASS magnitudes of B2 and
3C radio galaxies
table4.dat 106 90 Radio and optical parameters
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See also:
VIII/1 : The 3C and 3CR Catalogues (Edge+ 1959-1962)
VIII/36 : The Second Bologna Survey (Colla+ 1970-1974)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Source name (B2 HHMM+DDA or 3C NNN.N)
14- 18 F5.2 mag W1mag Wise W1 magnitude
20- 23 F4.2 mag e_W1mag rms uncertainty on W1mag
25- 29 F5.2 mag W2mag Wise W2 magnitude
31- 34 F4.2 mag e_W2mag rms uncertainty on W2mag
36- 40 F5.2 mag W3mag Wise W3 magnitude
42- 45 F4.2 mag e_W3mag rms uncertainty on W3mag
47- 51 F5.2 mag W4mag ?=- Wise W4 magnitude
53- 56 F4.2 mag e_W4mag ?=- rms uncertainty on W4mag
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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- 11 A11 --- Name Source name (B2 HHMM+DDA or 3C NNN.N)
14- 18 F5.2 mag FUV ?=- GALEX FUV magnitude
20- 23 F4.2 mag e_FUV ?=- rms uncertainty on FUV
25- 29 F5.2 mag NUV ?=- GALEX NUV magnitude
31- 34 F4.2 mag e_NUV ?=- rms uncertainty on NUV
36- 40 F5.2 mag umag SDSS u magnitude
42- 46 F5.2 mag gmag SDSS g magnitude
48- 52 F5.2 mag rmag SDSS r magnitude
54- 58 F5.2 mag imag SDSS i magnitude
60- 64 F5.2 mag zmag SDSS z magnitude
66- 70 F5.2 mag Jmag 2MASS J magnitude
72- 75 F4.2 mag e_Jmag rms uncertainty on Jmag
77- 81 F5.2 mag Hmag 2MASS H magnitude
83- 86 F4.2 mag e_Hmag rms uncertainty on Hmag
88- 92 F5.2 mag Kmag 2MASS K magnitude
94- 97 F4.2 mag e_Kmag rms uncertainty on Kmag
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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- 11 A11 --- Name Source name (B2 HHMM+DDA or 3C NNN.N)
14- 19 F6.3 [Msun] logM Galaxy mass
21- 24 F4.1 10+9yr Age Galaxy age
26- 31 F6.3 [Msun] C1g ? 2nd galaxy component logM for a (young)
galaxy model
33- 37 E5.2 yr C2g ? 2nd component Age for a (young) galaxy
model
39 A1 --- g [g] g for galaxy model
41- 45 F5.3 [10Lsun/nm] C1p ? 2nd galaxy component luminosity density
(in L_☉/Å), at the reference point
λ=2000Å, Lp.l2000Å,
for a power law
47- 50 F4.2 --- C2p ? 2nd galaxy component slope of power-law
(lambda-alpha), for a power law
52 A1 --- p [p] p for power law
54- 59 F6.1 --- chi2min Reduced minimum chi2 value
60 A1 --- n_chi2min [cd] Note on chi2min (1)
62- 66 F5.2 [-] logP ? Total power at 1.4GHz
68- 70 F3.1 --- FR ? FR type (2)
72 I1 --- SpCode [0/4]?=- Spectral type code (3)
74- 75 A2 --- Class Classification of the spectral type
according to the emission line ratios
determined here (4)
77 A1 --- l_LHa Limit flag on LHa
78- 83 F6.2 10+33W LHa ?=- Luminosity of Hα emission
85- 89 F5.2 mag XUV ?=- Ultraviolet excess
91- 93 F3.2 mag e_XUV ? rms uncertainty on XUV
96-100 F5.2 [-] logRw ?=- Logarithm of the ratio of the two
near-IR (W1 plus W2) and the two MIR
(W3 and W4) WISE luminosities,
log[L(W1+W2)/L(W3+W4)]
102-105 F4.2 [Msun] logMBH ? Black hole mass
106 A1 --- r_logMBH [efg] reference for logMBH (5)
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Note (1): Note as follows:
c = J, H, K systematically higher than the other bands, in many cases
resulting in high χ2 values
d = J, H, K systematically lower than the other bands, resulting in high
χ2 value
Note (2): Note that FR 3 refers to compact sources, while in a few cases
no FR type could be assigned
Note (3): Spectral type as follows:
0 = overall spectrum shows the typical absorption features of an inactive
early-type galaxy
1 = only very weak emission in Hα or [NII] but not much else
2 = low-excitation galaxies (LEGs; but with enough emission lines present
to allow the use of diagnostic diagrams)
3 = high-excitation galaxies (HEGs)
4 = if broad-line components are present as well
Note (4): Classification of the spectral type according to the emission line
ratios determined here as follows:
H = HII star forming
L = LINER
S = Seyfert
S1 = Seyfert type 1
A = AGN
C = Composite spectra, in which there is probably both star
formation and an AGN
Note (5): References as follows:
e = Hyperleda
f = Mezcua et al. (2011A&A...527A..38M 2011A&A...527A..38M)
g = Snellen et al. (2003MNRAS.342..889S 2003MNRAS.342..889S)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Nov-2015