Radio Astronomy Manuel Castillo ESA/ISDEFE Michel Breitfellner ESA/SERCO CTIF Workshop Oct 26th, 2016
Radio Astronomy What is Radio Astronomy? What its needed for RA? How do and what we observe with the antennas? Some Interesting Science Cases
Radio Astronomy: a first CONTACT Contact (1997): Jodie Foster at the Very Large Array (New Mexico, USA)
What is Radio Astronomy? States of Matter Solid Liquid Gas Plasma
What is Radio Astronomy?
What is Radio Astronomy? Electromagnetic Radiation
What is Radio Astronomy? Electromagnetic Radiation and the Earth Atmosphere
RADIO SKY (night and day)
What is Radio Astronomy? Closest Active Galaxy: interaction of an elliptical galaxy and a small spiral galaxy that formed a disk of gas and dust, birth of new stars.
What is Radio Astronomy?
What is Radio Astronomy? ABELL 2256 GALAXY CLUSTER: interaction between two galaxy clusters
ABELL 2256 GALAXY CLUSTER: unexpected physical processes in merging clusters long tails, halos, large relics What is Radio Astronomy?
RADIO SKY (night and day) Cygnus A Sagirarius A* RADIO GALAXIES GALACTIC CENTER QUASARS Cassiopeia A Orion Nebula SUPERNOVA REMNANTS STAR FORMING REGIONS
What we need for RA? Large size antennas Low noise amplifiers Large collecting area: better sensitivity Directional antennas (small beams): better resolution System noise reduced: better sensitivity
Radio Astronomy at the NASA s DSN PARTNeR educational antenna (34m) Geodesy (34m) DSS-63 (70m) DSS-54/55 (34m)
VIL-1 CESAR educational antenna CERT (15m) Radio Astronomy at ESAC
Radio Astronomy at the ESA s DSN VIL-1 CESAR educational antenna CERT (15m) Cassegrain antenna with altazimuthal mount Longitude: 3 o 57 5.70 W Latitude: 40 o 26 33.23 N Altitude: 655.15 m Azimuth range: 0-720 deg Elevation range: 0-90 deg Rate: 3 deg/s both axes
Services: Tracking Telemetry Telecommand Radiometric measurements (ranging, Doppler, meteo, autotrack angles) S-band antenna Radio Astronomy at Transmit the (2025-2120 ESA s MHz) DSN Receive (2200-2300 MHz) S-band beamwidth: 37 (at 2250MHz) Aperture efficiency: 65% Sensitivity (K/Jy): 0.042 (at 2250 MHz)
How do we observe with the antennas? SINGLE DISH Continuum observations Spectroscopy observations INTERFEROMETRIC OBSERVATIONS
How do we observe with the antennas? SINGLE DISH Continuum observations Spectroscopy observations Radio waves 10 5 x larger than optical waves: we need radio telescopes 10 5 larger to achieve same resolution. Several points from focal plane simultaneously: Just one point from focal plane: Airy disk
How do we observe with the antennas? SINGLE DISH 40m Yebes, ESP 64m Parkes, AUS 70m MDSCC, ESP 100m Effelsberg, DEU 100m Green Bank, USA 305m Arecibo, PRI 500m Guizhou, CHN
Continuum observations DEC scan DEC scan XDEC scan XDEC scan XDEC transit
Continuum emission THERMAL BLACK BODY RADIATION IONIZED GAS EMISSION (FREE-FREE) NON-THERMAL EMISSION (SYNCHROTON)
Continuum emission: Jupiter Thermal emission: black body Non-thermal emission: Synchrotron
Synchrotron Radiation Electromagnetic radiation emitted by electrons that are spiralling along, and therefore being constantly accelerated, in a magnetic field at a rate great enough for relativistic effects to be ATOMIC important. Predicted LINES: long HI ago, this radiation was first encountered in a particle accelerator called the synchrotron. Much of the radiation observed by radio astronomers originates in this fashion. MOLECULAR LINES: CO Synchrotron radiation from cosmic sources has a distinctive spectrum, or distribution of photons with energy. The radiation falls off with energy less rapidly than does the spectrum of radiation from a hot gas. When synchrotron radiation is observed in supernova remnants, cosmic jets, or other sources, it reveals information about the high-energy electrons and magnetic fields that are present.
Spectral line emission ATOMIC LINES: HI MOLECULAR LINES: CO
How do we observe with the antennas? INTERFEROMETRIC OBSERVATIONS
How do we observe with the antennas? INTERFEROMETRIC OBSERVATIONS
How do we observe with the antennas? YOUNG DOUBLE-SLIT INTERFEROMETRIC OBSERVATIONS Galaxy = torch Interferometric network = double-slit Visibility function = interference pattern on screen
How do we observe with the antennas? VLA NRAO New Mexico, USA ALMA ESO Atacama, CHL
How do we observe with the antennas? European VLBI Network (EVN) most sensitive interferometer thanks to the large antennas 32m Medicina 64m Sardinia 70m MDSCC 40m Yebes 76m Jodrell Bank 100m Effelsberg
How do we observe with the antennas? VLBA Interferometer for by 10 antennas (25m diameter) with same receivers.
How do we observe with the antennas? 10 m Radiastron (Spektr-R)
Some Interesting Science Cases Supernova remnants Radio galaxies and Quasars Star forming regions and beyond
RADIO SKY (night and day) Cygnus A Sagirarius A* RADIO GALAXIES GALACTIC CENTER QUASARS Cassiopeia A Orion Nebula SUPERNOVA REMNANTS STAR FORMING REGIONS
Supernova Remnant: Cassiopeia A 5 Image courtesy of Hubble Space Telescope/NRAO Strongest radio source in the sky! (apart from the Sun). Star died in ~1700 as a type II supernova. 10 light years across, 10000 ly away. UPV, February 12th, 2016
Galactic Centre: Sagittarius A* Sagittarius A* is a bright and very compact astronomical radio source at the center of the Milky Way, near the border of the constellations Sagittarius and Scorpius.. Sagittarius A* is thought to be the location of a supermassive black hole, like those that are now generally accepted to be at the centers of most spiral and elliptical galaxies. Image courtesy of Hubble Space Telescope/NRAO False-color (right) image of the radio wave emission covers the inner 10 arcseconds (0.3 pc) of the Milky Way. The compact radio source Sgr A* is the bright red spot at the center of the frame. The diffuse green-red emission strongest to the south of Sgr A* is from ionized material that may be spiraling inwards. Distance around 1400 light years.
Unified Standard Model for Active Galaxies and Quasars Active galaxy: 20-25% more luminous from central region, Radio Galaxy: very luminous in radio, non-thermal emission UPV, February 12th, 2016
Unified Standard Model for Active Galaxies and Quasars Active galaxy: 20-25% more luminous from central region, Radio Galaxy: very luminous in radio, non-thermal emission RADIO GALAXY QUASAR BLAZAR UPV, February 12th, 2016
Radio Galaxy: Cygnus A (3C405) Image courtesy of NRAO/IAU One of the most brilliant objects in the radio sky, double-lobe radio galaxy: 1 arcmin= 600 million light years (Milky Way is 180000 ly, 55Kpc, 1pc=3.3ly)
Quasar: 3C286 Image courtesy of Hubble Space Telescope/Merlin Bright Quasar at a distance of 3900 million ligh years
Star forming HII regions: Scutum 30 Image courtesy of NRO Ring of HII regions: formation sites of massive stars, located at the Galactic disk. Distribution of ionized gas from free-free emission. Distance around 1000 light years.
Beyond: Wow! signal On August 15, 1977, a strong narrowband radio signal was received by Ohio State University's Big Ear radio telescope, in the United States, then assigned to a SETI project. The signal appeared to come from the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin. Image courtesy of NRO