We present the first cosmological parameter constraints using measurements of type Ia supernovae ( SNe Ia ) from the Dark Energy Survey Supernova Program ( DES-SN ) .
The analysis uses a subsample of 207 spectroscopically confirmed SNe Ia from the first three years of DES-SN , combined with a low-redshift sample of 122 SNe from the literature .
Our “ DES-SN3YR ” result from these 329 SNe Ia is based on a series of companion analyses and improvements covering SN Ia discovery , spectroscopic selection , photometry , calibration , distance bias corrections , and evaluation of systematic uncertainties .
For a flat \Lambda CDM model we find a matter density \Omega _ { m } = 0.331 \pm 0.038 .
For a flat w CDM model , and combining our SN Ia constraints with those from the cosmic microwave background ( CMB ) , we find a dark energy equation of state w = -0.978 \pm 0.059 , and \Omega _ { m } = 0.321 \pm 0.018 .
For a flat w _ { 0 } w _ { a } CDM model , and combining probes from SN Ia , CMB and baryon acoustic oscillations , we find w _ { 0 } = -0.885 \pm 0.114 and w _ { a } = -0.387 \pm 0.430 .
These results are in agreement with a cosmological constant and with previous constraints using SNe Ia ( Pantheon , JLA ) .