NASA Hubble: New precise mass map of a distant galaxy cluster

This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MCS J0416.1-2403. 

This is one of six being studied by the Hubble Frontier Fields programme. 

This programme seeks to analyse the mass distribution in these huge clusters and to use the gravitational lensing effect of these clusters, to peer even deeper into the distant Universe. 

Credit: ESA/Hubble, NASA, HST Frontier Fields

Astronomers using the NASA/ESA Hubble Space Telescope have mapped the mass within a galaxy cluster more precisely than ever before.

Created using observations from Hubble Frontier Fields observing programme, the map shows the amount and distribution of mass within MCS J0416.1-2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun.

The detail in this mass map was made possible thanks to the unprecedented depth of data provided by new Hubble observations, and the cosmic phenomenon known as strong gravitational lensing.

Measuring the amount and distribution of mass within distant objects in the Universe can be very difficult.

A trick often used by astronomers is to explore the contents of large clusters of galaxies by studying the gravitational effects they have on the light from very distant objects beyond them.

This is one of the main goals of Hubble Frontier Fields, an ambitious observing programme scanning six different galaxy clusters, including MCS J0416.1-2403, the cluster shown in this stunning new image.

Large clumps of mass in the Universe warp and distort the space-time around them. Acting like lenses, they appear to magnify and bend light that travels through them from more distant objects.

Despite their large masses, the effect of galaxy clusters on their surroundings is usually quite minimal.

For the most part they cause what is known as weak lensing, making even more distant sources appear as only slightly more elliptical or smeared across the sky.

However, when the cluster is large and dense enough and the alignment of cluster and distant object is just right, the effects can be more dramatic.

The images of normal galaxies can be transformed into rings and sweeping arcs of light, even appearing several times within the same image.

This effect is known as strong lensing, and it is this phenomenon, seen around the six galaxy clusters targeted by the Hubble Frontier Fields programme, that has been used to map the mass distribution of MCS J0416.1-2403, using the new Hubble data.

"The depth of the data lets us see very faint objects and has allowed us to identify more strongly lensed galaxies than ever before," explains Mathilde Jauzac of Durham University, UK, and Astrophysics & Cosmology Research Unit, South Africa, lead author of the new Frontier Fields paper.

"Even though strong lensing magnifies the background galaxies they are still very far away and very faint. The depth of these data means that we can identify incredibly distant background galaxies."

"We now know of more than four times as many strongly lensed galaxies in the cluster than we did before."

Using Hubble's Advanced Camera for Surveys, the astronomers identified 51 new multiply imaged galaxies around the cluster, quadrupling the number found in previous surveys and bringing the grand total of lensed galaxies to 68.

Because these galaxies are seen several times this equates to almost 200 individual strongly lensed images which can be seen across the frame.

This effect has allowed Jauzac and her colleagues to calculate the distribution of visible and dark matter in the cluster and produce a highly constrained map of its mass.