J/A+A/708/A46 NOCTURNE narrow-line Seyfert 1 radio spectrum (Berton+, 2026)
NOCTURNE. I. The radio spectrum of narrow-line Seyfert 1 galaxies.
Berton M., Jarvela E., Chen S., Crepaldi L., Varglund I., Coloma Puga M.,
Jimenez-Gallardo A., Lahteenmaki A., Panda S., Piscitelli C., Tortosa A.
<Astron. Astrophys. 708, A46 (2026)>
=2026A&A...708A..46B 2026A&A...708A..46B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Redshifts ; Spectroscopy
Keywords: radiation mechanisms: non-thermal - galaxies: active -
galaxies: jets - galaxies: Seyfert - radio continuum: galaxies
Abstract:
The origin of the radio emission in active galactic nuclei (AGN) is
still debated. Multiple physical mechanisms can contribute to the
spectrum at these frequencies, including relativistic jets, the jet
base, outflows, star formation, and synchrotron emission from the hot
corona. Recently, new extreme radio variability has been observed in
the class of low-mass/high-Eddington AGN known as narrow-line
Seyfert 1 (NLS1) galaxies, suggesting that another, more exotic
mechanism may also play a role, especially at frequencies above 10GHz.
To investigate this relatively unexplored area of the radio spectrum,
we observed a sample of 50 NLS1s with the Karl G. Jansky Very Large
Array (JVLA), and 20 of them were observed twice. In this sample, 24
sources were not detected, while the others are typically
characterized by a steep spectrum that can be modeled with a power
law. We also identified two new candidate jetted NLS1s, including a
high-frequency peaker, which is an extremely young relativistic jet.
We found no significant variability in the sources observed twice. We
conclude that the radio spectrum of NLS1s is typically dominated by
optically thin emission, likely from low-power outflows, or by
circumnuclear star formation, with a limited contribution from
relativistic jets. Further studies at different spatial scales and at
other wavelengths are necessary to fully constrain the origin of the
radio emission in this class of active galaxies.
Description:
In this paper, we report on our new JVLA observations of a sample of
50 NLS1s at 15, 22, and 33 GHz. Approximately half of the sources, 26,
were detected at least at one frequency. We studied their radio
properties by adding available data from the literature. Their
spectrum is almost always steep and can be reproduced by a power law.
The emission possibly originates in radiation pressure-driven
non-relativistic outflows or, less likely, in circumnuclear star
formation. The origin of these seemingly common outflows may lie in
the strong radiation pressure produced by the high accretion typical
of NLS1s. A couple of sources may harbor small-scale relativistic
jets, and one in particular may be a high-frequency peaker. It is
possible that more relativistic jets are present, but we cannot
confirm their presence with the available data. These results confirm
the complexity and diverse nature of the NLS1 class. Additional
multiwavelength studies are necessary to fully characterize these
sources, and understand their role in the AGN life cycle.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 50 The sample
table2.dat 83 46 Measurements for all the sources detected at
least at one frequency in one epoch
tablea1.dat 43 35 Upper limits for sources with no detection
tablea2.dat 146 50 Archival radio data for the sources with at
least one JVLA detection
tablea3.dat 85 46 Luminosity of the sources with at least one
detection at 15, 22, or 33GHz
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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- 10 A10 --- SName Short name of the source (JHHMM+DDMM)
12- 34 A23 --- 6dFGS Name of the source in the 6dFGS catalog
(6dFGSgJHHMMSS.s+DDMMSS)
36- 37 I2 h RAh Right ascension (J2000)
39- 40 I2 min RAm Right ascension (J2000)
42- 46 F5.2 s RAs Right ascension (J2000)
48 A1 --- DE- Declination sign (J2000)
49- 50 I2 deg DEd Declination (J2000)
52- 53 I2 arcmin DEm Declination (J2000)
55- 58 F4.1 arcsec DEs Declination (J2000)
60- 64 F5.3 --- z Redshift
66- 70 F5.3 kpc/arcsec Scale Spatial scale
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- SName Short name
12- 16 I5 d MJD Modified Julian date of the observation
18- 19 I2 --- rms(Ku) rms of the map at 15GHz
21 A1 --- l_Sp(Ku) Limit flag on Sp(Ku)
22- 25 I4 uJy/beam Sp(Ku) Peak flux density at 15GHz
27- 29 I3 uJy/beam e_Sp(Ku) ? Peak flux density at 15GHz error
31- 34 I4 uJy Si(Ku) ? Integrated flux density at 15GHz
36- 38 I3 uJy e_Si(Ku) ? Integrated flux density at 15GHz error
40- 41 I2 --- rms(K) ? rms of the map at 22GHz
42 A1 --- u_rms(K) [*] Note on rms(K) (1)
44 A1 --- l_Sp(K) Limit flag on Sp(K)
45- 48 I4 uJy/beam Sp(K) ? Peak flux density at 22GHz
50- 51 I2 uJy/beam e_Sp(K) ? Peak flux density at 22GHz error
52 A1 --- n_Sp(K) [*] Note on Sp(K) (1)
54- 57 I4 uJy Si(K) ? Integrated flux density at 22GHz
59- 61 I3 uJy e_Si(K) ? Integrated flux density at 22GHz error
62 A1 --- n_Si(K) [*] Note on Si(K) (1)
64- 65 I2 --- rms(Ka) rms of the map at 33GHz
67 A1 --- l_Sp(Ka) Limit flag on Sp(Ka)
68- 71 I4 uJy/beam Sp(Ka) Peak flux density at 33GHz
73- 74 I2 uJy/beam e_Sp(Ka) ? Peak flux density at 33GHz error
76- 79 I4 uJy Si(Ka) ? Integrated flux density at 33GHz
81- 83 I3 uJy e_Si(Ka) ? Integrated flux density at 33GHz error
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Note (1): The * sign indicates a technical problem with the 22GHz observations
of J0413-0050, where no data were taken.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- SName Shoer name
12- 16 I5 d MJD Modified Julian date of the observation
18- 20 I3 --- rms(Ku) rms of the map at 15GHz
22 A1 --- l_Sp(Ku) Limit flag on Sp(Ku)
23- 26 I4 uJy/beam Sp(Ku) Upper limit of the peak flux density at 15GHz
28- 30 I3 --- rms(K) rms of the map at 22GHz
32 A1 --- l_Sp(K) Limit flag on Sp(K)
33- 35 I3 uJy/beam Sp(K) Upper limit of the peak flux density at 22GHz
37- 38 I2 --- rms(Ka) rms of the map at 33GHz
40 A1 --- l_Sp(Ka) Limit flag on Sp(Ka)
41- 43 I3 uJy/beam Sp(Ka) Upper limit of the peak flux density at 33GHz
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- SName Source name
12- 15 F4.2 uJy/beam FIRp ?=- Peak flux density in FIRST
17- 20 F4.2 uJy FIRi ?=- Integrated flux density in FIRST
23- 27 F5.2 uJy NVSSi ?=- Peak flux density in NVSS
29- 31 F3.1 uJy e_NVSSi ? Peak flux density in NVSS error
33- 36 F4.2 uJy/beam VL1p ?=- Peak flux density in VL1
38- 41 F4.2 uJy/beam e_VL1p ?=- Peak flux density in VL1 error
43- 46 F4.2 uJy VL1i ?=- Integrated flux density in VL1
48- 51 F4.2 uJy e_VL1i ? Integrated flux density in VL1 error
53- 57 F5.2 uJy/beam VL2p ?=- Peak flux density in VL2
59- 62 F4.2 uJy/beam e_VL2p ? Peak flux density in VL2 error
64- 68 F5.2 uJy VL2i ?=- Integrated flux density in VL2
70- 73 F4.2 uJy e_VL2i ? Integrated flux density in VL2 error
75- 80 F6.1 uJy S5i ?=- Integrated flux density in S5
82- 86 F5.1 uJy e_S5i ? Integrated flux density in S5 error
88- 93 F6.1 uJy/beam S5p ?=- Peak flux density in S5
95- 98 F4.1 uJy/beam e_S5p ? Peak flux density in S5 error
100-102 I3 uJy/beam S9p ?=- Peak flux density in S9
104-105 I2 uJy/beam e_S9p ? Peak flux density in S9 error
107-111 F5.2 uJy RACSi ?=- Integrated flux density in RACS
113-116 F4.2 uJy e_RACSi ? Integrated flux density in RACS error
118-122 F5.2 uJy/beam RACSp ?=- Peak flux density in RACS
124-127 F4.2 uJy/beam e_RACSp ? Peak flux density in RACS error
129-132 F4.1 uJy TGSSi ?=- Integrated flux density in TGSS
134-137 F4.1 uJy e_TGSSi ?=- Integrated flux density in TGSS error
139-142 F4.1 uJy/beam TGSSp ?=- Peak flux density in TGSS
144-146 F3.1 uJy/beam e_TGSSp ?=- Peak flux density in TGSS error
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- SName Source name
12- 16 I5 d MJD Modified Julian date of the observation
18 A1 --- l_logLp(Ku) Limit flag on logLp(Ku)
19- 23 F5.2 [uJy/beam] logLp(Ku) logarithm of the peak luminosity
at 15GHz
25- 28 F4.2 [uJy/beam] e_logLp(Ku) ? logarithm of the peak luminosity
at 15GHz error
30- 34 F5.2 [uJy] logLi(Ku) ? logarithm of the integrated luminosity
at 15GHz
36- 39 F4.2 [uJy] e_logLi(Ku) ? logarithm of the integrated luminosity
at 15GHz error
41 A1 --- l_logLp(K) Limit flag on logLp(K)
42- 46 F5.2 [uJy/beam] logLp(K) ? logarithm of the peak luminosity
at 22GHz
48- 51 F4.2 [uJy/beam] e_logLp(K) ? logarithm of the peak luminosity
at 22GHz error
52 A1 --- n_logLp(K) [*] Note on logLp(K) (1)
53- 57 F5.2 [uJy] logLi(K) ? logarithm of the integrated luminosity
at 22GHz
59- 62 F4.2 [uJy] e_logLi(K) ? logarithm of the integrated luminosity
at 22GHz error
64 A1 --- l_logLp(Ka) Limt flag on logLp(Ka)
65- 69 F5.2 [uJy/beam] logLp(Ka) logarithm of the peak luminosity
at 33GHz
71- 74 F4.2 [uJy/beam] e_logLp(Ka) ? logarithm of the peak luminosity
at 33GHz
76- 80 F5.2 [uJy] logLi(Ka) ? logarithm of the integrated luminosity
at 33GHz
82- 85 F4.2 [uJy] e_logLi(Ka) ? logarithm of the integrated luminosity
at 33GHz error
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Note (1): The asterisk indicates a technical problem at 22GHz observation for
J0413-0050, no data were taken in this band.
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Acknowledgements:
Marco Berton, marco.berton(at)eso.org
(End) Patricia Vannier [CDS] 13-Feb-2026