These postage-stamp-size images reveal 36 young galaxies caught in the act of merging with other galaxies. These galaxies appear as they existed many billions of years ago. Astronomers have dubbed them "tadpole galaxies" because of their distinct knot-and-tail shapes, which suggest that they are engaging in galactic mergers.
The galaxies were captured in 2004 in the Hubble Space Telescope's Ultra Deep Field (HUDF) survey of thousands of distant galaxies. They are part of more than 165 tadpole galaxies in the HUDF studied recently by a team of astronomers. The team was looking for indications of black hole activity in these young galaxies. A characteristic signature of such activity is a fluctuation in brightness over time, an indication that a black hole is feasting on surrounding stars and gas. The flickering light does not come from the black hole itself but from the area immediately surrounding the black hole. Astronomers did not see brightness fluctuations in any of the tadpole galaxies they surveyed. They did, however, observe the fluctuations in 46 different faint galaxies in the HUDF. These galaxies existed millions of years after the tadpole galaxies. This result suggests that black holes did not begin eating when galaxies merged. Rather, it took several hundred million years for the gas and stars from the merger to arrive on the black hole's dinner plate and become visible as flickering light. This finding agrees with recent computer models which predicted that the feeding habits of black holes would become visible after galactic mergers.
Each postage-stamp image is roughly 84,000 light-years on a side, which is about the size of our Milky Way Galaxy today. The tadpole galaxies are shown in the middle of each image and are considerably smaller than today's giant galaxies. The image was taken by Hubble's Advanced Camera for Surveys.
Credits
NASA, A. Straughn, S. Cohen, and R. Windhorst (Arizona State University), and the HUDF team (Space Telescope Science Institute)| About The Object | |
|---|---|
| Object Name | Tadpole Galaxies in the Hubble Ultra Deep Field (HUDF) |
| Object Description | Young galaxies, Tadpole Galaxies |
| R.A. Position | 03h 31m 59.99s |
| Dec. Position | -27° 48' 0.0" |
| Constellation | Fornax |
| About The Data | |
| Data Description | This image of the HUDF was created from HST data from the following proposal: : S. Beckwith, S. Malhotra, M. Giavalisco, N. Panagia, J. Rhoads, M. Stiavelli, R. Somerville, S. Casertano, B. Margon, C. Blades, J. Caldwell, and M. Clampin (STScI), M. Corbin (CSC), M. Dickinson, H. Ferguson, and A. Fruchter (STScI), R. Hook (STScI/ECF), S. Jogee, A. Koekemoer, R. Lucas, M. Sosey, and L. Bergeron (STScI). The science team includes: A.N. Straughn, S.H. Cohen, R.E. Ryan Jr, N.P. Hathi, R.A. Windhorst, & R.A. Jansen (Arizona State University), A.M. Koekemoer, N. Pirzkal, C. Xu, B. Mobasher, S. Malhotra, L.-G.Strolger, and J.E. Rhoads (STScI). |
| Instrument | HST>ACS/WFC |
| Exposure Dates | September 24, 2003 - January 16, 2004, Exposure Time: 11.3 days |
| Filters | F435W (B), F606W (V), F775W (i), F850LP (z) |
| About The Image | |
| Color Info | Blue: F435W (B) Green: F606W (V), F775W (i) Red: F850LP (z) |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
