DESIVAST: A Catalog of Low-Redshift Voids using Data from the DESI DR1 Bright Galaxy Survey
We present three separate void catalogs created using a volume-limited sample of the DESI Year 1 Bright Galaxy Survey. We use the algorithms VoidFinder and V2 to construct void catalogs out to a redshift of z=0.24. We obtain 1,461 interior voids with VoidFinder, 420 with V2 using REVOLVER pruning, and 295 with V2 using VIDE pruning. Comparing our catalog with an overlapping SDSS void catalog, we find generally consistent void properties but significant differences in the void volume overlap, which we attribute to differences in the galaxy selection and survey masks. These catalogs are suitable for studying the variation in galaxy properties with cosmic environment and for cosmological studies.
Great Nature News Feature article on the recent DESI Survey results on dark energy
With a final quote by Jim Peebles: “I find it very difficult to imagine that ΛCDM is the end of the story. It’s too simple.”
https://www.nature.com/articles/d41586-024-01273-4
#Cosmology #DarkEnergy #ΛCDM #JimPeebles #DESI #survey #DESIsurvey #BAO #BaryonAcousticOscillations #galaxies #astronomy #astrophysics #astrodon #Nature #news #science
Dark energy is tearing the Universe apart. What if the force is weakening?
The first set of results from a pioneering cosmic-mapping project hints that the repulsive force known as dark energy has changed over 11 billion years, which would alter ideas about how the Universe has evolved and what its future will be.
A search for dwarf galaxies in the Local Void, using data of the DESI Legacy Imaging Surveys
by Igor Karachentsev and co-authors
https://arxiv.org/abs/2312.04930
📷 Images of 12 new dwarf galaxies from DESI Legacy Imaging Surveys found in the Local Void region. Each image size is 2′ × 2′. North is to the top and East is to the left.
#galaxies #dwarfgalaxies #localvoid #void #voids #desi #survey #desisurvey #cosmology #cosmography #astronomy #astrophysics #astodon #space #science #research
A search for new dwarf galaxies outside the nearby groups
We undertook a search for new nearby dwarf galaxies outside the known groups in the Local Volume using the data on DESI Legacy Imaging Surveys. In a wide sky area of $\sim$5000 square degrees directed toward the Local Void, we found only 12 candidates to nearby low mass galaxies. Almost all of them are classified as irregular or transition type dwarfs. Additionally, we examined areas of the sky exposed with the Hyper Suprime Camera of the Subaru telescope ($\sim$700 square degrees) and found nine more candidates to nearby dwarfs. Finally, nine candidates to the Local Volume were selected by us from the Zaritsky's SMUDG catalog that contains 7070 ultra-diffuse objects automatically detected in the whole area of the DESI surveys. We estimated a fraction of quiescent dSph galaxies in the general cosmic field to be less than 10 percent.
Congratulations to DESI (Dark Energy Spectroscopic Instrument) for their first detection of the baryon acoustic oscillations (BAO) signal using early data.
https://arxiv.org/abs/2304.08427
#universe #cosmology #bao #desi #survey #desisurvey #darkenergy #astronomy #astrophysics #astrodon #space #science #research
First Detection of the BAO Signal from Early DESI Data
We present the first detection of the baryon acoustic oscillations (BAO) signal obtained using unblinded data collected during the initial two months of operations of the Stage-IV ground-based Dark Energy Spectroscopic Instrument (DESI). From a selected sample of 261,291 Luminous Red Galaxies spanning the redshift interval 0.4 < z < 1.1 and covering 1651 square degrees with a 57.9% completeness level, we report a ~5 sigma level BAO detection and the measurement of the BAO location at a precision of 1.7%. Using a Bright Galaxy Sample of 109,523 galaxies in the redshift range 0.1 < z < 0.5, over 3677 square degrees with a 50.0% completeness, we also detect the BAO feature at ~3 sigma significance with a 2.6% precision. These first BAO measurements represent an important milestone, acting as a quality control on the optimal performance of the complex robotically-actuated, fiber-fed DESI spectrograph, as well as an early validation of the DESI spectroscopic pipeline and data management system. Based on these first promising results, we forecast that DESI is on target to achieve a high-significance BAO detection at sub-percent precision with the completed 5-year survey data, meeting the top-level science requirements on BAO measurements. This exquisite level of precision will set new standards in cosmology and confirm DESI as the most competitive BAO experiment for the remainder of this decade.
The DESI Peculiar Velocity Survey, the largest survey of galaxies peculiar velocities planned to date. Great stuff for the future of mapping the universe with cosmic flows!
https://arxiv.org/abs/2302.13760
More on DESI the Dark Energy Spectroscopic Instrument: https://www.desi.lbl.gov/
#universe #cosmology #cosmicflows #cosmography #desi #survey #desisurvey #darkenergy #astronomy #astrophysics #astrodon #space #science #research
Target Selection for the DESI Peculiar Velocity Survey
We describe the target selection and characteristics of the DESI Peculiar
Velocity Survey, the largest survey of peculiar velocities (PVs) using both the
fundamental plane (FP) and the Tully-Fisher (TF) relationship planned to date.
We detail how we identify suitable early-type galaxies (ETGs) for the FP and
suitable late-type galaxies (LTGs) for the TF relation using the photometric
data provided by the DESI Legacy Imaging Survey DR9. Subsequently, we provide
targets for 373 533 ETGs and 118 637 LTGs within the DESI 5-year footprint. We
validate these photometric selections using existing morphological
classifications. Furthermore, we demonstrate using survey validation data that
DESI is able to measure the spectroscopic properties to sufficient precision to
obtain PVs for our targets. Based on realistic DESI fiber assignment
simulations and spectroscopic success rates, we predict the final DESI PV
Survey will obtain $\sim$133 000 FP-based and $\sim$53 000 TF-based PV
measurements over an area of 14 000 $\mathrm{deg^{2}}$. We forecast the ability
of using these data to measure the clustering of galaxy positions and PVs from
the combined DESI PV and Bright Galaxy Surveys (BGS), which allows for
cancellation of cosmic variance at low redshifts. With these forecasts, we
anticipate a $4\%$ statistical measurement on the growth rate of structure at
$z<0.15$. This is over two times better than achievable with redshifts from the
BGS alone. The combined DESI PV and BGS will enable the most precise tests to
date of the time and scale dependence of large-scale structure growth at
$z<0.15$.
Daniel Pomarède
