J/A+A/634/A9 PKS 1549-79 ALMA data cubes & continuum images (Maccagni+, 2020)
The flickering nuclear activity of Fornax A.
Maccagni F.M., Murgia M., Serra P., Govoni F., Morokuma-Matsui K.,
Kleiner D., Buchner S., Jozsa G.I.G., Kamphuis P., Makhathini S.,
Molnar D.Cs., Prokhorov D.A., Ramaila A., Ramatsoku M., Thorat K.,
Smirnov O.
<Astron. Astrophys. 634, A9 (2020)>
=2020A&A...634A...9M 2020A&A...634A...9M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Radio sources
Keywords: galaxies: individual: Fornax A - galaxies: individual: NGC 1316 -
galaxies: active - radio continuum: galaxies - galaxies: jets -
radiation mechanisms: non-thermal
Abstract:
We present new observations of Fornax A taken at ∼1GHz with the
MeerKAT telescope and at ∼6GHz with the Sardinia Radio Telescope
(SRT). The sensitive (noise ∼16uJy/beam), high-resolution (<10'')
MeerKAT images show that the lobes of Fornax A have a double-shell
morphology, where dense filaments are embedded in a diffuse and
extended cocoon. We study the spectral properties of these components
by combining the MeerKAT and SRT observations with archival data
between 84MHz and 217GHz.
For the first time, we show that multiple episodes of nuclear activity
must have formed the extended radio lobes. The modelling of the radio
spectrum suggests that the last episode of injection of relativistic
particles into the lobes started ∼24Myr ago and stopped 12Myr ago.
More recently (∼3Myr ago), a less powerful and short (<1Myr) phase
of nuclear activity generated the central jets. Currently, the core
may be in a new active phase. It appears that Fornax A is rapidly
flickering. The dense environment around Fornax A has lead to a
complex recent merger history for this galaxy, including mergers
spanning a range of gas contents and mass ratios, as shown by the
analysis of the galaxy's stellar- and cold-gas phases. This complex
recent history may be the cause of the rapid, recurrent nuclear
activity of Fornax A.
Description:
1GHz and 6GHz images of Fornax A taken with the MeerKAT and SRT
telescopes. Tables with the flux spectral flux density of different
components of Fornax A between 84MHz and 217GHz.
Objects:
---------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------
03 22 41.7 -37 12 30 Fornax A = NGC 1316
---------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 88 52 Flux densities of Fornax A between
84MHz and 217GHz
list.dat 119 9 List of fits images
fits/* . 9 Individual fits images
--------------------------------------------------------------------------------
Byte-by-byte Description of file:tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.4 GHz Freq Frequency of measured flux density of
Fornax A
11- 12 A2 --- n_Freq Note (1)
15- 19 F5.1 Jy FluxDens ? Flux density measured in this work
20 A1 --- u_FluxDens [)] Uncertainty flag on FluxDens
22- 26 F5.1 Jy e_FluxDens ? Error on flux density
28- 34 F7.1 Jy FluxDensMcK ? Flux density measured by
McKinley et al. 2015MNRAS.446.3478M 2015MNRAS.446.3478M
37- 38 I2 % e_FluxDensMcK ? Percentage error on flux density
41- 43 I3 Jy FluxDensPer ? Flux density measured by
Perley et al. 2017ApJS..230....7P 2017ApJS..230....7P,
Cat. J/ApJS/230/7
45- 46 I2 % e_FluxDensPer ? Percentage error on flux density
49- 88 A40 -- Ref Telescope used for the measurements, or the
reference to the published fluxes
--------------------------------------------------------------------------------
Note (1): Note on Freq as follows:
* = indicates flux densities that have not been included in the study
of the SED
** = WMAP: Wilkinson Microwave Anisotropy Probe
(Bennett et al. 2013ApJS..208...20B 2013ApJS..208...20B, Cat. J/ApJS/208/20)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 50 A21 "datime" Obs.date Observation date
52- 56 I5 Kibyte size Size of FITS file
58- 85 A28 --- FileName Name of FITS file, in subdirectory fits
87-119 A33 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Filippo Maccagni, filippo.maccagni(at)inaf.it
(End) Patricia Vannier [CDS] 23-Jan-2020