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    Category Astronomy/Space

    Non-detection of Key Signal allows Astronomers to Determine what the First Galaxies were – and weren’t – like

    November 29, 2022, Categories  Astronomy/Space

    Observations by the NASA/ESA Hubble Space Telescope have taken advantage of gravitational lensing to reveal the largest sample of the faintest and earliest known galaxies in the universe.
    Early galaxies capture by the NASA/ESA Hubble Telescope
    Credit: NASA Goddard

    Researchers have been able to make some key determinations about the first galaxies to exist, in one of the first astrophysical studies of the period in the early Universe when the first stars and galaxies formed, known as the cosmic dawn.

    Using data from India’s SARAS3 radio telescope, researchers led by the University of Cambridge were able to look at the very early Universe — just 200 million years after the Big Bang — and place limits on the mass and energy output of the first stars and galaxies.

    Counterintuitively, the researchers were able to place these limits on the earliest galaxies by not finding the signal they had been looking for, known as the 21-centimetre hydrogen line.

    This non-detectio...

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    NASA’s IXPE helps Solve Black Hole Jet mystery

    November 25, 2022, Categories  Astronomy/Space

    This illustration shows NASA’s IXPE spacecraft, at right, observing blazar Markarian 501, at left. A blazar is a black hole surrounded by a disk of gas and dust with a bright jet of high-energy particles pointed toward Earth. The inset illustration shows high-energy particles in the jet (blue). When the particles hit the shock wave, depicted as a white bar, the particles become energized and emit X-rays as they accelerate. Moving away from the shock, they emit lower-energy light: first visible, then infrared, and radio waves. Farther from the shock, the magnetic field lines are more chaotic, causing more turbulence in the particle stream.
    Credits: NASA/Pablo Garcia

    Some of the brightest objects in the sky are called blazars...

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    Astronomers Observe Intra-Group Light – the elusive glow between distant galaxies

    November 24, 2022, Categories  Astronomy/Space

    igl_between_galaxies_400138.jpg
    Light ‘between’ the galaxies – the ‘intra-group light’ – however dim, is radiated from stars stripped from their home galaxy. Image: Supplied.

    Pioneering a new technique, researchers have peered into the extremely faint light that exists between galaxies to describe the history and state of orphan stars. An international team of astronomers have turned a new technique onto a group of galaxies and the faint light between them — known as ‘intra-group light’ — to characterise the stars that dwell there.

    Lead author of the study published in MNRAS, Dr Cristina Martínez-Lombilla from the School of Physics at UNSW Science, said “We know almost nothing about intra-group light.

    “The brightest parts of the intra-group light are ~50 times fainter than the darkest night sky on Earth...

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    International team observes Innermost Structure of Quasar Jet

    November 24, 2022, Categories  Astronomy/Space

    Radio astronomy images of the 3C 273 jet
    Radio astronomy images of the 3C 273 jet. The close-up view on the left is the deepest look yet into the plasma jet of the quasar 3C 273. The image in the center shows the extended structure of the jet. The image on the right is a visible light image of the quasar taken by the Hubble Space Telescope. The radio observations were made by the Global Millimeter VLBI Array (GMVA) joined by the Atacama Large Millimeter/submillimeter Array (ALMA) and the High Sensitivity Array (HSA). (Credits: Hiroki Okino and Kazunori Akiyama; GMVA+ALMA and HSA images: Okino et al.; HST Image: ESA/Hubble & NASA) Original size (1.1MB)

    An international team of scientists has observed the narrowing of a quasar jet for the first time by using a network of radio telescopes across the world...

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