J/A+A/699/A159 ESPRESSO Redshift Drift Experiment. I. (Trost+, 2025)
The ESPRESSO Redshift Drift Experiment:
I. High-resolution spectra of the Lyman-alpha forest of QSO J052915.80-435152.0.
Trost A., Marques C.M.J., Cristiani S., Cupani G., Di Stefano S.,
D'Odorico V., Guarneri F., Martins C.J.A.P., Milakovic Dinko , Pasquini L.,
Genova Santos R., Molaro P., Murphy M.T., Nunes N.J., Schmidt T.M.,
Alibert Y., Boutsia K., Calderone G., Gonzalez Hernandez J.I., Grazian A.,
Lo Curto G., Palle E., Pepe F., Porru M., Santos N.C., Sozzetti A.,
Suarez Mascareno A., Zapatero Osorio M.R.
<Astron. Astrophys. 699, A159 (2025)>
=2025A&A...699A.159T 2025A&A...699A.159T (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Spectroscopy
Keywords: instrumentation: spectrographs - quasars: absorption lines -
cosmology: observations - quasars: individual: J052915.80-435152.0
Abstract:
The measurement of the temporal evolution in the redshift of distant
objects, the redshift drift, is a probe of universal expansion and
cosmology.
We perform the first steps towards a measurement of such effect using
the Lyman-alpha forest in the spectra of bright quasars as a tracer of
cosmological expansion. Our goal is to determine to which precision a
velocity shift measurement can be carried out with the signal-to-noise
(S/N) level currently available and whether this precision aligns with
previous theoretical expectations. A precise assessment of the
achievable measurement precision is fundamental for estimating the
time required to carry out the whole project.
We acquire 12 hours of ESPRESSO observations distributed over 0.875
years of the brightest quasar known, J052915.80-435152.0 (z=3.962), to
obtain high-resolution spectra of the Lyman-alpha forest, with median
S/N of ∼86 per 1km/s pixel at the continuum. We divide the
observations into two epochs and analyse them using both a
pixel-by-pixel method and a model-based approach. This comparison
allows us to estimate the velocity shift between the epochs, as well
as the velocity precision that can be achieved at this S/N. The
model-based method is calibrated using high-resolution simulations of
the intergalactic medium, and it provides greater accuracy compared to
the pixel-by-pixel approach.
We measure a velocity drift of the Lyman-alpha forest consistent with
zero: {DELTA}v=-1.25±4.45m/s, equivalent to a cosmological drift of
dv/dt=-1.43±5.09m/s/yr or dz/dt=(-2.19±7.77)x10-8yr-1. The
measurement uncertainties are on par with the expected precision. We
estimate that reaching a 99% detection of the cosmic drift requires a
monitoring campaign of 5400 hours of integration time over 54 years
with an ELT and an ANDES-like high-resolution spectrograph.
Description:
We set out to assess the feasibility of measuring the redshift drift
signal using Lyman-alpha forest spectroscopy, based on the
highest-quality data available prior to the commissioning of
ELT/ANDES. We used new, high-resolution and high-S/N spectra of the
most luminous known quasar in the Universe, J052915.80-435152.0 (SB2;
zem = 3.962), obtained with ESPRESSO at the VLT.
Objects:
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RA (2000) DE Designation(s)
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05 29 15.80 -43 51 52.0 QSO J052915.80-435152.0 = SMSS J052915.80-435152.0
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 74 210 Parameters obtained from the fit of all detected
metal transitions with λ>603nm
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 29 A29 --- Trans Atomic transition
31- 39 F9.7 --- z Redshift of absorption line
41- 48 E8.3 --- e_z Uncertainty on redshift
50- 55 F6.3 [cm-2] logN Logarithmic column density of absorption line
57- 61 F5.3 [cm-2] e_logN Uncertainty on logarithmic column density
63- 68 F6.3 km/s b Doppler parameter of absorption line
70- 74 F5.3 km/s e_b Uncertainty on Doppler parameter
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Acknowledgements:
Andrea Trost, andrea.trost(a)inaf.it
(End) Patricia Vannier [CDS] 02-Jun-2025