The Dark Energy Survey and Operations: Year 6 – The Finale

Diehl, H. T.; Neilsen, Eric H.; Zenteno, A.; Marshall, J. L.; Sgeir, R.; Wang, Q.; Markwardt, Larissa; Walker, A. R.; Zhang, Y.; Turner, David J.; Allam, S.; García, A.; Plazas, A. A.; Huterer, Dragan; Abbott, T. M. C.; Petravick, D.; Johnson, _______; Martini, Paul; Tucker, D. L.; Bechtol, K.; Kent, Stephen M.; Gruen, D.; Flaugher, B.; Martı́nez-Vázquez, C. E.; Honscheid, K.; Soares-Santos, M.; James, D. J.; Reil, K.; Ávila, S.; Smith, J. A.; Hollowood, D. L.; Zhang, Z.; Chen, Y.C.; Yanny, B.; Bhargava, S.; Paz-Chinchón, F.; Gruendl, R. A.; Morgan, R.; Chen, A.; Kuropatkin, N.; Gill, M. S.; DeRose, J.; Bernstein, G. M.; Lathrop, A.; Palmese, A.; Campos, A.; Kirby, M.R.; Li, T.S.; Troja, A.; Prochaska, Travis; Costa, L. Da; Krön, Richard G.; Wilkinson, R. D.; Vivas, A. K.; Muir, J.; Herner, K.; Hutchinson, Timothy A.; Amon, A.; Everett, S.; Wagoner, Erika L.; Murphy, Michael T.; Jain, Bhuvnesh; Frieman, Joshua A.

doi:10.2172/1596042

“…Each night, our DECam observations covered the entire 90% localization area, and reached depths comparable to or deeper than all other follow-up teams issuing GCN circulars documenting their observations. The localization area falls entirely within the Dark Energy Survey (DES) footprint, a 5000 sq deg region of the southern sky that has been observed with DECam over the course of 6 yr (Diehl et al 2019). We searched for candidate EM counterparts by comparing the images collected during the real-time observations to archival DES data.…”

Section: Introductionmentioning

confidence: 99%

Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey

Morgan

¹

,

Soares-Santos

²

,

Annis

³

et al. 2020

ApJ

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On 2019 August 14, the LIGO and Virgo Collaborations detected gravitational waves from a black hole and a 2.6 solar mass compact object, possibly the first neutron star-black hole merger. In search of an optical counterpart, the Dark Energy Survey (DES) obtained deep imaging of the entire 90% confidence level localization area with Blanco/DECam 0, 1, 2, 3, 6, and 16 nights after the merger. Objects with varying brightness were detected by the DES Pipeline, and we systematically reduced the candidate counterparts through catalog matching, light-curve properties, host-galaxy photometric redshifts, Southern Astrophysical Research spectroscopic follow-up observations, and machine-learning-based photometric classification. All candidates were rejected as counterparts to the merger. To quantify the sensitivity of our search, we applied our selection criteria to full light-curve simulations of supernovae and kilonovae as they would appear in the DECam observations. Because the source class of the merger was uncertain, we utilized an agnostic, three-component kilonova model based on tidally disrupted neutron star (NS) ejecta properties to quantify our detection efficiency of a counterpart if the merger included an NS. We find that, if a kilonova occurred during this merger, configurations where the ejected matter is greater than 0.07 solar masses, has lanthanide abundance less than 10 −8.56 , and has a velocity between 0.18c and 0.21c are disfavored at the 2σ level. Furthermore, we estimate that our background reduction methods are capable of associating gravitational wave signals with a detected electromagnetic counterpart at the 4σ level in 95% of future follow-up observations.

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“…e-ASTROGAM will also detect a significant number of supernovae in nearby galaxies, thus addressing fundamental issues in the explosion mechanisms of both core-collapse and thermonuclear supernovae. The gamma-ray line data ( 56 Ni, 56 Co) will provide a much better understanding of Type Ia supernovae [7,10] and their evolution with look-back time and metallicity, which is a pre-requisite for their use as standard candles for precision cosmology.…”

Section: Nucleosynthesis and The Chemical Enrichment Of Our Galaxymentioning

confidence: 99%

“…Without a space telescope like e-ASTROGAM in orbit, the power of future multi-wavelength and multi-messenger synergy and scientific serendipity, will be depressed hindering potential important discoveries. This is particularly true in case of nearby supernovae or kilonovae explosions, because a MeV space observatory like e-ASTROGAM will represent the ground-breaking instrument able to directly probe nucleosynthesis, with the identification of the origin of key nuclear isotopes [7,10], thought to be responsible for the creation of approximately half the abundances of the nuclei heavier than iron, and shedding…”

Section: Introductionmentioning

confidence: 99%

The e-ASTROGAM space mission for MeV-GeV gamma-ray and multi-messenger astrophysics

Ciprini¹,

Angelis²,

Tatischeff³

2020

Proceedings of Accretion Processes in Cosmic Sources – II — PoS(APCS2018)

0

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Future high-energy, multi-frequency survey astronomy, time-domain and multi-parameters inference, multimessenger astro-particle physics, will not be able to grow in a really comprehensive, synergetic and serendipitous way, if an important, broad, electromagnetic window in the Universe, where interesting and multiple physical processes occur, is left unobserved. In this view e-ASTROGAM is a project of breakthrough space observatory mission, with large international interest, characterized by a detector composed by a silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the, so called, poorly-known MeV-energy sky, through the detection of photons from about 150 keV to 3 GeV energy. e-ASTROGAM is optimized for simultaneous detection of Compton and pair-producing photon events, with optimal capabilities in gammaray continuum, nuclear line spectroscopy, spatial imaging, gamma-ray polarization measurement, and with a large field of view, essential for survey/time-domain multi-messenger synergy. All these capabilities, will be able to open a rich, interdisciplinary, science menu in a electromagnetic band, the MeV Universe, probed only in a shallow way by previous satellites. e-ASTROGAM will be the groundbreaking instrument in case of nearby (about <20 Mpc) supernovae and kilonovae events, directly probing nucleosynthesis processes with a MeV line sensitivity one to two orders of magnitude better than previous/current instruments. The origin of key nuclear isotopes, responsible for the creation of ∼ 50% the abundances of the nuclei heavier than iron, and for radioactive/chemical evolution of our Galaxy will be accurately determined. e-ASTROGAM is also a general-purpose satellite for broad and different scientific communities, with a rich scientific potential, placed in the enormous spectral energy vacuum between the multitude of soft-X-ray satellites (Athena for example) and the (40 GeV) band of the Cherenkov Telescope Array (CTA). Powerful, multi-messenger experiments such as LISA, LIGO, Virgo, KAGRA, Einstein Telescope, Cosmic Explorer, IceCube-gen2, KM3NeT, SKA, ALMA, JWST, E-ELT, LSST, Athena, CTA will have a consistent leap in science results if coupled with e-ASTROGAM or similar all-sky/wide survey MeV space telescopes.

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“…DES obtained ∼ 10 × 90 s exposures in five broadband filters, grizY (Neilsen et al 2019). 2 DES observed with gri in dark time, iz in gray time, and zY in bright time, with each field of the footprint being observed 2-3 times per year (Diehl et al 2016(Diehl et al , 2019Neilsen et al 2019). The 5σ point-source depth of the DES exposures is estimated to be grizY ∼ (24.3, 24.1, 23.5, 22.9, 21.5) (Morganson et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Identifying RR Lyrae Variable Stars in Six Years of the Dark Energy Survey

Stringer

¹

,

Drlica-Wagner

²

,

Macri

³

et al. 2021

ApJ

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We present a search for RR Lyrae stars using the full six-year data set from the Dark Energy Survey covering ∼5000 deg2 of the southern sky. Using a multistage multivariate classification and light-curve template-fitting scheme, we identify RR Lyrae candidates with a median of 35 observations per candidate. We detect 6971 RR Lyrae candidates out to ∼335 kpc, and we estimate that our sample is >70% complete at ∼150 kpc. We find excellent agreement with other wide-area RR Lyrae catalogs and RR Lyrae studies targeting the Magellanic Clouds and other Milky Way satellite galaxies. We fit the smooth stellar halo density profile using a broken-power-law model with fixed halo flattening (q = 0.7), and we find strong evidence for a break at R 0 = 32.1 − 0.9 + 1.1 kpc with an inner slope of n 1 = − 2.54 − 0.09 + 0.09 and an outer slope of n 2 = − 5.42 − 0.14 + 0.13 . We use our catalog to perform a search for Milky Way satellite galaxies with large sizes and low luminosities. Using a set of simulated satellite galaxies, we find that our RR Lyrae-based search is more sensitive than those using resolved stellar populations in the regime of large (r h ≳ 500 pc), low-surface-brightness dwarf galaxies. A blind search for large, diffuse satellites yields three candidate substructures. The first can be confidently associated with the dwarf galaxy Eridanus II. The second has a distance and proper motion similar to the ultrafaint dwarf galaxy Tucana II but is separated by ∼5 deg. The third is close in projection to the globular cluster NGC 1851 but is ∼10 kpc more distant and appears to differ in proper motion.

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The Dark Energy Survey and Operations: Year 6 – The Finale

Cited by 20 publications

References 23 publications

Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey

Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey

The e-ASTROGAM space mission for MeV-GeV gamma-ray and multi-messenger astrophysics

Identifying RR Lyrae Variable Stars in Six Years of the Dark Energy Survey

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