Artist's Concept Dark Energy Universe Acceleration

New proof reveals that the important thing assumption made within the discovery of darkish power is in error.

Excessive precision age relationship of supernova host galaxies reveals that the luminosity evolution of supernovae is critical sufficient to query the very existence of darkish power.

Essentially the most direct and strongest proof for the accelerating universe with darkish power is supplied by the gap measurements utilizing sort Ia supernovae (SN Ia) for the galaxies at excessive redshift. This result’s primarily based on the idea that the corrected luminosity of SN Ia by way of the empirical standardization wouldn’t evolve with redshift. 

New observations and evaluation made by a group of astronomers at Yonsei College (Seoul, South Korea), along with their collaborators at Lyon College and KASI, present, nevertheless, that this key assumption is almost certainly in error. The group has carried out very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cowl many of the reported close by early-type host galaxies of SN Ia, from which they obtained probably the most direct and dependable measurements of inhabitants ages for these host galaxies. They discover a vital correlation between SN luminosity and stellar inhabitants age at a 99.5% confidence degree.

As such, that is probably the most direct and stringent check ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting youthful with redshift (look-back time), this outcome inevitably signifies a severe systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is critical sufficient to query the very existence of darkish power. When the luminosity evolution of SN is correctly taken under consideration, the group discovered that the proof for the existence of darkish power merely goes away (see Determine 1).

Luminosity Evolution Mimicking Dark Energy

Determine 1. Luminosity evolution mimicking darkish power in supernova (SN) cosmology.
The Hubble residual is the distinction in SN luminosity with respect to the cosmological mannequin with out darkish power (the black dotted line). The cyan circles are the binned SN knowledge from Betoule et al. (2014). The pink line is the evolution curve primarily based on our age relationship of early-type host galaxies. The comparability of our evolution curve with SN knowledge reveals that the luminosity evolution can mimic Hubble residuals used within the discovery and inference of the darkish power (the black stable line). Credit score: Yonsei College

Commenting on the outcome, Prof. Younger-Wook Lee (Yonsei Univ., Seoul) who was main the venture mentioned; “Quoting Carl Sagan, extraordinary claims require extraordinary proof, however I’m not certain we have now such extraordinary proof for darkish power. Our outcome illustrates that darkish power from SN cosmology, which led to the 2011 Nobel Prize in Physics, is likely to be an artifact of a fragile and false assumption.”

Different cosmological probes, comparable to CMB (Cosmic Microwave Background) and BAO (Baryonic Acoustic Oscillations), are additionally recognized to supply some oblique and “circumstantial” proof for darkish power, but it surely was just lately steered that CMB from Planck mission now not helps the concordance cosmological mannequin which can require new physics (Di Valentino, Melchiorri, & Silk 2019). Some investigators have additionally proven that BAO and different low-redshift cosmological probes may be per a non-accelerating universe with out darkish power (see, for instance, Tutusaus et al. 2017). On this respect, the current outcome exhibiting the luminosity evolution mimicking darkish power in SN cosmology is essential and could be very well timed.

This result’s harking back to the well-known Tinsley-Sandage debate within the 1970s on luminosity evolution in observational cosmology, which led to the termination of the Sandage venture initially designed to find out the destiny of the universe.

This work primarily based on the group’s 9-year effort at Las Campanas Observatory 2.5-m telescope and at MMT 6.5-m telescope was introduced on the 235th assembly of the American Astronomical Society held in Honolulu on January fifth (2:50 PM in cosmology session, presentation No. 153.05). Their paper was additionally accepted for publication in The Astrophysical Journal and was printed in January 2020 difficulty.

Reference: “Early-Kind Host Galaxies of Kind Ia Supernovae. II. Proof for Luminosity Evolution in Supernova Cosmology” by Yijung Kang, Younger-Wook Lee (Yonsei Univ., South Korea), Younger-Lo Kim (Lyon Univ., France), Chul Chung (Yonsei Univ.), & Chang Hee Ree (KASI, South Korea), 20 January 2020, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ab5afc
arXiv: 1912.04903

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