Swift Ultraviolet Image Gallery

M81 - UVOT
M81 Image from the Ultra Violet/Optical Telescope (UVOT)
Image Credit: NASA / Swift / E. Hoversten, Penn State University (PSU)

M81 - SDSS
M81 Image from the Sloan Digital Sky Survey (SDSS)
Image Credit: Sloan Digital Sky Survey (SDSS)

NASA and Penn State University have released new images from the Swift Gamma Ray Burst Explorer. The ability to see exquisite details in the ultraviolet is illustrated in the images above.

At left, is a three-filter (uvw1, uvm2 and uvw2) ultraviolet image of Messier 81, a spiral galaxy 12 million light-years away in the Ursa Major constellation. At right is a visible image from the Sloan Digital Sky Survey. M81’s companion galaxy, Holmberg IX, is barely visible in the optical, but its young stars shine brightly in the ultraviolet.

Swift carries three instruments for detailed observations of gamma ray bursts. The X-ray Telescope (XRT) and the UV/Optical Telescope (UVOT) were built by Penn State, Leicester University and the Mullard Space Science Laboratory (both in England) and at the Osservatorio Astronomico di Brera (in Italy). The third instrument is the Burst Alert Telescope (BAT). Swift was launched into a low-Earth orbit on a Delta 7320 rocket on November 20, 2004.

Sloan Digital Sky Survey 3D Map And Dark Energy

Baryon Acoustic Vibrations
Baryon Acoustic Vibrations at 5.5 Billion Light Years From SDSS Data
Image Credit: E.M. Huff, the SDSS-III team, and the South Pole Telescope team.
Graphic by Zosia Rostomian.

Dark Energy drives the accelerating expansion of the Universe, and the imprint can be found in the distribution of galaxies.

Now, researchers, including several associated with the University of Arizona in Tucson, have published a series of six papers (see below) concerning the distribution of galaxies 5.5 billion light years from Earth, using data from the Sloan Digital Sky Survey.

The papers detail how mapping the position of galaxies can measure how fast the Universe was expanding six billion years ago. The expansion is the result of Dark Energy, which makes up 72% of the universe in which we live (the remainder is Dark Matter (23%) and atoms (5%), found in intergalactic gas and stars).

The image above illustrates how variations in the cosmic microwave background (due to baryon acoustic vibrations during inflation, which followed the Big Bang) are reflected by later distribution of galaxies, and measuring the distribution of galaxies at different times reflects the accelerating expansion of the universe. The original work on the accelerating expansion came from observations of type Ia supernovae in 1998 and and 1999, and led to the Nobel Prize in 2011.

The Baryon Oscillation Spectroscopic Survey (BOSS) is one of four SDSS surveys, and the team of scientists and engineers that make up the team are the authors of these six papers.

Will Percival, a professor at the University of Portsmouth in the United Kingdom, and one of the leaders of the analysis team noted that:

We have only one-third of the data that BOSS will deliver, and that has already allowed us to measure how fast the Universe was expanding six billion years ago — to an accuracy of two percent.

This coupled with the previously released data on the distribution of galaxies at 3.8 billion light years, shows the accelerating expansion: the rate at 3.8 billion light years is more than the earlier rate at 5.5 billion light years.

Due to the original oscillations in the universe, theory predicts that the average distance between galaxies would be 500 million light years. And this is what the BOSS results have shown. They are the best measurements to date.

From the SDSS article we have the references to the arxiv papers:

Hanny’s Voorwerp

Hanny's Voorwerp

Original Galaxy Zoo image
of Hanny’s Voorwerp from the
Sloan Digital Sky Survey (SDSS) 2007
Image Credit: Galaxy Zoo

Dutch schoolteacher Hanny van Arkel, discovered the strange green “voorwerp” (Dutch for “object”) in 2007 while working on the Galaxy Zoo Project. Today, she presented the Hubble image seen below at the AAS meeting in Seattle.

The Hubble Site press release comments that:

Galaxy Zoo enlists the public to help classify more than a million galaxies cataloged in the Sloan Digital Sky Survey. The project has expanded to include the Hubble Zoo, in which the public is asked to assess tens of thousands of galaxies in deep imagery from the Hubble Space Telescope.

The object is located near IC 2497, a spiral galaxy about 700 million light years from the Earth.

It appears that the giant galaxy began tidally shredding a dwarf galaxy a billion years ago. The result is a trail of stars, gas and dust extending from IC 2497. At the end of this 300-light-year-long gaseous streamer is Hanny’s Voorwerp.

What makes the situation unusual is that the process of shredding the dwarf galaxy fed the quasar at the heart of IC 2497, spewing intense ultraviolet light and X-rays. These bombarded the Voorwerp and heated the gas.

The quasar turned off, apparently quite suddenly, between 70,000 and 100,000 years ago. The green color is attributed to glowing oxygen energized by the now quiet quasar.

Hanny's Voorwerp

Hanny’s Voorwerp in the green band of SDSS
Image Credit: Galaxy Zoo / ING

The Hubble Space Telescope image below from the Wide Field Camera 3 and Advanced Camera for Surveys, shows the yellow and orange star forming region in the upper right portion of the Voorwerp. Observations show that the quasar’s beam caused the collapse of the region and triggered the star formation, the youngest of which are only several million years old.

Professor William C. Keel is a member of the Galaxy Zoo team and leader of the Hubble study. He teaches at the University of Alabama. Keel notes:

The star clusters are localized, confined to an area that is over a few thousand light-years wide. The region may have been churning out stars for several million years. They are so dim that they have previously been lost in the brilliant light of the surrounding gas.

What we’re seeing is the afterglow from the quasar. This implies that it might flicker on and off, which is typical of quasars, but we’ve never seen such a dramatic change happen so rapidly.

Radio astronomy shows that the green pod of gas is part of a large structure that wraps around the nearby spiral galaxy. The Voorwerp is the only optically visible portion of this structure.

Hanny's Voorwerp
Hanny’s Voorwerp from the Hubble Space Telescope
Image Credit: NASA / ESA / W. Keel (University of Alabama), and the Galaxy Zoo team.