J/A+A/671/A43 PKS1413+135 OH and HI at z=0.247 with MeerKAT (Combes+, 2023)
PKS 1413+135: OH and HI at z=0.247 with MeerKAT.
Combes F., Gupta N., Muller S., Balashev S., Deka P., Emig K.L.,
Kloeckner H.-R., Klutse D., Knowles K., Mohapatra A., Momjian E.,
Noterdaeme P., Petitjean P., Salas P., Srianand R., Wagenveld J.D.
<Astron. Astrophys. 671, A43 (2023)>
=2023A&A...671A..43C 2023A&A...671A..43C (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; BL Lac objects ; Spectra, radio
Keywords: BL Lacertae objects: individual: PKS1413+135 - galaxies: general -
galaxies: kinematics and dynamics - quasars: absorption lines -
galaxies: ISM
Abstract:
The BL Lac PKS 1413+135 was observed by the Large Survey Project
"MeerKAT Absorption Line Survey" (MALS) in the L-band, at 1139MHz and
1293-1379MHz, targeting the Hi and OH lines in absorption at
z=0.24671. The radio continuum is thought to come from a background
object at redshift lower than 0.5, as suggested by the absence of
gravitational images. The Hi absorption line is detected at high
signal-to-noise, with a narrow central component, and a red wing,
confirming previous results. The OH 1720MHz line is clearly detected
in (maser) emission, peaking at a velocity shifted by -10 to -15km/s
with respect to the HI peak. The 1612MHz line is lost due to radio
interferences. The OH 1667MHz main line is tentatively detected in
absorption, but not the 1665MHz one. Over 30 years, a high variability
is observed in optical depths, due to the rapid changes of the line of
sight, caused by the superluminal motions of the radio knots. The HI
line has varied by 20% in depth, while the OH-1720MHz depth has varied
by a factor 4. The position of the central velocity and the widths
also varied. The absorbing galaxy is an early-type spiral (maybe S0)
seen edge-on, with a prominent dust lane, covering the whole disk.
Given the measured mass concentration, and the radio continuum size at
centimeter wavelengths (100 mas corresponding to 400pc at z=0.25), the
width of absorption lines from the nuclear regions are expected up to
250km/s. The narrowness of the observed lines (<15km/s) suggest that
the absorption comes from an outer gas ring, as frequently observed in
S0 galaxies. The millimetric lines are even narrower (<1km/s), which
corresponds to the continuum size restricted to the core. The core
source is covered by individual 1pc molecular clouds, of column
density a few 1022cm-2, which is compatible with the gas screen
detected in X-rays.
Description:
The field centered at PKS 1413+135 was observed in the frame
of MALS on October 16, 2020, using 59 antennas of the MeerKAT-64 array
and 32K mode of the SKA Reconfigurable Application Board (SKARAB)
correlator. The total bandwidth of 856MHz centered at 1283.9869MHz
was split into 32,768 frequency channels. The resultant frequency
resolution is 26.123kHz, or 6.1km/s, at the center of the band.
3 ascii spectra from MeerKAT, HI and OH main and satellite lines.
Objects:
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RA (2000) DE Designation(s)
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14 15 58.81 +13 20 23.7 PKS1413+135 = QSO B1413+135
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hi-all.dat 40 2304 MeerKAT HI-21cm spectrum
oh-main.dat 40 2304 MeerKAT OH-main lines spectrum
oh-1720.dat 15 17 MeerKAT OH-1720 spectrum
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Byte-by-byte Description of file: hi-all.dat oh-main.dat
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Bytes Format Units Label Explanations
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5- 20 E16.10 Hz Freq Frequency
24- 40 E17.11 Jy Flux Flux, continuum subtracted
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Byte-by-byte Description of file: oh-1720.dat
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Bytes Format Units Label Explanations
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1- 4 F4.0 km/s Vel Velocity
7- 15 E9.4 Jy Flux Flux, continuum subtracted
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Acknowledgements:
Francoise Combes, francoise.combes(at)obspm.fr
(End) Patricia Vannier [CDS] 13-Dec-2022