English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We have searched 4.5 deg 2  of archival  Hubble Space Telescope /Advanced Camera for Surveys ( HST /ACS) images for cosmic strings, identifying close pairs of similar, faint galaxies and selecting groups whose alignment is consistent with gravitational lensing by a long, straight string. We find no evidence for cosmic strings in five large‐area  HST  treasury surveys (covering a total of 2.22 deg 2 ) or in any of 346 multifilter guest observer images (1.18 deg 2 ). Assuming that simulations accurately predict the number of cosmic strings in the Universe, this non‐detection allows us to place upper limits on the dimensionless Universal cosmic string tension of   G μ/ c  2  &lt; 2.3 × 10 −6   and cosmic string density of  Ω s  &lt; 2.1 × 10 −5   at the 95 per cent confidence level (marginalizing over the other parameter in each case). We find four dubious cosmic string candidates in 318 single‐filter guest observer images (1.08 deg 2 ), which we are unable to conclusively eliminate with existing data. The confirmation of any of these candidates as cosmic strings would imply   G μ/ c  2 ≈ 10 −6   and  Ω s ≈ 10 −5  . However, we estimate that there is at least a 92 per cent chance that these string candidates are random alignments of galaxies. If we assume that these candidates are indeed false detections, our final limits on   G μ/ c  2   and  Ω s   fall to  6.5 × 10 −7   and  7.3 × 10 −6  , respectively. Due to the extensive sky coverage of the  HST /ACS image archive, the above limits are universal. They are quite sensitive to the number of fields being searched and could be further reduced by more than a factor of 2 using forthcoming  HST  data.

Direct observation of cosmic strings via their strong gravitational lensing effect – II. Results from the HST /ACS image archive