NASA’s Fermi Satellite Kicks Off a Blazar-detecting Bonanza

A long time ago in a galaxy half the universe away, a flood of high-energy gamma rays began its journey to Earth. When they arrived in April, NASA’s Fermi Gamma-ray Space Telescope caught the outburst, which helped two ground-based gamma-ray observatories detect some of the highest-energy light ever seen from a galaxy so distant. The observations provide a surprising look into the environment near a supermassive black hole at the galaxy’s center and offer a glimpse into the state of the cosmos 7 billion years ago.

“When we looked at all the data from this event, from gamma rays to radio, we realized the measurements told us something we didn’t expect about how the black hole produced this energy,” said Jonathan Biteau at the Nuclear Physics Institute of Orsay, France. He led the study of results from the Very Energetic Radiation Imaging Telescope Array System (VERITAS), a gamma-ray telescope in Arizona. Continue reading NASA’s Fermi Satellite Kicks Off a Blazar-detecting Bonanza

Appearances of the Refsdal supernova

This video shows the three appearances of the Refsdal supernova in the galaxy cluster MACS J1149.5+2223. Calculations showed that the first image of the supernova appeared in 1998 — an event not observed with a telescope. The second image produced an almost perfect Einstein Cross, which was observed in November 2014 (heic1505). The latest appearance was observed by the NASA/ESA Hubble Space telescope on 11 December 2015, as correctly predicted by seven different models.
The positions of all three events are highlighted in this video with animated supernovae, even though the Einstein Cross event is also visible in the original image.
http://www.spacetelescope.org/videos/heic1525a/

The hottest white dwarf in the Galaxy

The hottest white dwarf in the Galaxy

Diagram of the Milky Way showing our Sun, the white dwarf, and the gas cloud relative to our neighbor galaxy, the Large Magellanic Cloud (adajcent to it the Small Magellanic Cloud). The white dwarf RX J0439.8-6809 and the gas cloud are between us and the Large Magellanic Cloud. Credit: Philipp Richter/University of Potsdam

Astronomers at the Universities of Tübingen and Potsdam have identified the hottest white dwarf ever discovered in our Galaxy. With a temperature of 250,000 degrees Celsius, this dying star at the outskirts of the Milky Way has already even entered its cooling phase. The researchers also were the first to observe an intergalactic gas cloud moving towards the Milky Way — indicating that galaxies collect fresh material from deep space, which they can use to make new stars. These findings are published in the latest Astronomy & Astrophysics [Analysis of HST/COS spectra of the bare C–O stellar core H1504+65 and a high-velocity twin in the Galactic halo].
Read more at www.sciencedaily.com

A supermassive black hole in action

Copyright NASA, ESA, S. Baum & C. O’Dea (RIT), R. Perley & W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Copyright NASA, ESA, S. Baum & C. O’Dea (RIT), R. Perley & W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Scientists often use the combined power of multiple telescopes to reveal the secrets of the Universe – and this image is a prime example of when this technique is strikingly effective.

The yellow-hued object at the centre of the frame is an elliptical galaxy known as Hercules A, seen by the Earth-orbiting NASA/ESA Hubble Space Telescope. In normal light, an observer would only see this object floating in the inky blackness of space.

However, view Hercules A with a radio telescope, and the entire region is completely transformed. Stunning red–pink jets of material can be seen billowing outwards from the galaxy – jets that are completely invisible in visible light. They are shown here as seen by the Karl G. Jansky Very Large Array radio observatory in New Mexico, USA. These radio observations were combined with the Hubble visible-light data obtained with the Wide Field Camera 3 to create this striking composite.

The two jets are composed of hot, high-energy plasma that has been flung from the centre of Hercules A, a process that is driven by a supermassive black hole lurking at the galaxy’s heart. This black hole is some 2.5 billion times the mass of the Sun, and around a thousand times more massive than the black hole at the centre of our Milky Way galaxy.

Hercules A’s black hole heats material and accelerates it to nearly the speed of light, sending it flying out into space at phenomenally high speeds. These highly focused jets lose energy as they travel, eventually slowing down and spreading out to form the cloud-like lobes seen here.

The multiple bright rings and knots seen within these lobes suggest that the black hole has sent out numerous successive bursts of material over the course of its history. The jets stretch for around 1.5 million light-years – roughly 15 times the size of the Milky Way.

Hercules A, also known as 3C 348, lies around two billion light-years away. It is one of the brightest sources of radio emission outside our Galaxy.

This image was originally published in November 2012.

Read more at www.esa.int

Oxymoronic Black Hole Provides Clues to Growth

A Sloan Digital Sky Survey image of RGG 118, a galaxy containing the smallest supermassive black hole ever detected. The inset is a Chandra image showing hot gas around the black hole. Credits: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS

A Sloan Digital Sky Survey image of RGG 118, a galaxy containing the smallest supermassive black hole ever detected. The inset is a Chandra image showing hot gas around the black hole.
Credits: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS

Astronomers using NASA’s Chandra X-ray Observatory and the 6.5-meter Clay Telescope in Chile have identified the smallest supermassive black hole ever detected in the center of a galaxy. This oxymoronic object could provide clues to how larger black holes formed along with their host galaxies 13 billion years or more in the past.

Astronomers estimate this supermassive black hole is about 50,000 times the mass of the sun. This is less than half the mass of the previous smallest black hole at the center of a galaxy. Continue reading Oxymoronic Black Hole Provides Clues to Growth

Gravitational Constant Appears Universally Constant, Pulsar Study Suggests

The NSF's Robert C. Byrd Green Bank Telescope, part of the National Radio Astronomy Observatory. Credit: NRAO/AUI/NSF

The NSF’s Robert C. Byrd Green Bank Telescope, part of the National Radio Astronomy Observatory. Credit: NRAO/AUI/NSF

Gravity, one of the four fundamental forces of nature, appears reassuringly constant across the Universe, according to a decades-long study of a distant pulsar. This research helps to answer a long-standing question in cosmology: Is the force of gravity the same everywhere and at all times? The answer, so far, appears to be yes.

Astronomers using the National Science Foundation’s (NSF) Green Bank Telescope (GBT) in West Virginia and its Arecibo Observatory in Puerto Rico conducted a 21-year study to precisely measure the steady “tick-tick-tick” of a pulsar known as PSR J1713+0747. This painstaking research produced the best constraint ever of the gravitational constant measured outside of our Solar System. Continue reading Gravitational Constant Appears Universally Constant, Pulsar Study Suggests