J/A+A/679/A30 Reduced GTC spectrum towards Q1218+0832 (Fynbo+, 2023)
The galaxy counterpart and environment of the dusty damped Lyman-alpha absorber
at z=2.226 towards Q1218+0832.
Fynbo J.P.U., Christensen L.B., Geier S.J., Heintz K.E., Krogager J.-K.,
Ledoux C., Milvang-Jensen B., Moller P., Vejlgaard S., Viuho J., Ostlin G.
<Astron. Astrophys. 679, A30 (2023)>
=2023A&A...679A..30F 2023A&A...679A..30F (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Galaxies
Keywords: quasars: general - quasars: absorption lines
Abstract:
We report on further observations of the field of the quasar
Q1218+0832. Geier et al. (2019A&A...625L...9G 2019A&A...625L...9G) presented the discovery
of the quasar resulting from a search for quasars reddened and dimmed
by dust in foreground Damped Lyman-alpha Absorbers (DLAs). The DLA is
remarkable by having a very large HI column density close to
1022cm-2. Its dust extinction curve shows the 2175Å-bump known
from the Local Group. It also shows absorption from cold gas
exemplified by CI and CO-molecules. We here present narrow-band
observations of the field of Q1218+0832 and also use archival HST
image to search for the galaxy counterpart of the DLA. No emission
from the DLA galaxy is found neither in the narrow-band imaging nor in
the HST image. In the HST image, we can probe down to an impact
parameter of 0.3arcsec and a 3-sigma detection limit of 26.8 mag per
arcsec2. In the narrow-band image, we probe down to 0 arcsec impact
parameter and detect nothing down to a 3-sigma detection limit of
about 3*10-17erg/s/cm2. We do detect a bright Lyman-alpha emitter
59arcsec south of Q1218+0832 with a flux of 3*10-16erg/s/cm2. We
conclude that the DLA galaxy must be located at very small impact
parameter (<0.3arcsec, 2.5kpc) or is optically dark. Also, the DLA
galaxy most likely is part of a galaxy group.
Description:
Spectrum of a galaxy in the field.
Those observations were obtained with the Optical System for Imaging
and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at
the Gran Telescopio Canarias (GTC). We used the R1000B grism and a
1.23 arcsec-wide slit providing a resolution of
λ/{DELTA}λ=500 and a wavelength coverage of
3600-7770Å. The spectrum was taken at a high airmass of 2.0, as the
object was only observable briefly at the beginning of the night, but
otherwise under excellent observing conditions.
Objects:
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RA (2000) DE Designation(s)
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12 18 30.09 +08 32 15.4 Q1218+0832 = SDSS J121830.09+083215.4
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gtcspec.dat 40 2047 Reduced GTC spectrum
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Byte-by-byte Description of file: gtcspec.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda Wavelength (vacuum)
11- 25 E15.9 10mW/m2/nm Flux Flux (in erg/s/cm2/Å)
27- 40 E14.9 10mW/m2/nm e_Flux Flux error (in erg/s/cm2/Å)
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Acknowledgements:
Johan Fynbo, jfynbo(at)nbi.ku.dk
(End) Patricia Vannier [CDS] 11-Sep-2023