From IAC via Manu Garcia: “OTHELLO reveals a population of “ghost galaxies” in the Universe”

From Manu Garcia, a friend from IAC.

The universe around us.
Astronomy, everything you wanted to know about our local universe and never dared to ask.


From Instituto de Astrofísica de Canarias – IAC

The census OTELO (OSIRIS Tunable Emission Line Object survey)

Composite image of OTELO field. Field explored covers less than 50 arc minutes square -the that resembles a 13 times smaller area than the full Moon and enrolled in known as Extended Groth Strip, an area of ​​the sky between the constellations Osa Major and Bootes has been deeply observed by other telescopes and instruments in complementary branches of the electromagnetic spectrum. In the description of the image the color red is assigned to the integrated data OTELO using tunable filters of OSIRIS in the GTC, while the blue and green colors correspond to the bands graphic Canada-France-Hawaii, respectively. Credit: OTHELLO.

CFHT Telescope, Maunakea, Hawaii, USA, at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

Thanks to the OSIRIS instrument, installed in the Gran Telescopio Canarias, has been conducting the census deeper galaxies to date (OTELO), the results could affect what we now know about the formation and evolution of galaxies.

IAC Gran Telescopio Canarias OSIRIS spectrograph

OTHELLO, which gets its name “OSIRIS Tunable Emission Line Object survey” is the census of galaxies with emission lines deeper than has been done until today. This record, which includes more than 11,000 of these objects, has been performed using the OSIRIS (Optical System for Imaging and low Resolution Integrated-Intermediate-Spectroscopy) instrument installed in the Gran Telescopio Canarias (GTC). The GTC is the largest optical telescope and fully adjustable infrared world, because the collection capacity in light of its primary mirror 10.4 meters in diameter, so it is an excellent window into the depths of the Cosmos.

“OSIRIS was designed to be able to detect a hypothetical population of galaxies which had hitherto remained hidden. These are objects that can not be seen in other surveys of galaxies, but appearing in images obtained with OSIRIS, through the use of its tunable filters, which make it unique among the instruments for telescopes class 8-10 meters ” explains Jordi Cepa, principal investigator of this census, the first results will be published shortly in the journal Astronomy and Astrophysics.

OSIRIS tunable filters detect galaxies with emission lines, ie, galaxies possessing ionized gas (such as low consumption lamps that are in our homes). This gas can be ionized by a stellar star formation much larger than the sun, or by violent processes around supermassive black holes at the centers of galaxies mass. Some of these galaxies, however, do not emit enough light to be detected with conventional filters, so have remained hidden until now. Without a complete census, you can not understand how they evolve the properties of galaxies, in the same way it would not be possible to study the evolution of humans being restricted only to persons over 50 years.

The Great Canary Telescope. Credit: IAC.

Built in collaboration with IAC in Mexico, OSIRIS observed the sky in the optical range of the spectrum, ie, with the light of heaven that is capable of perceiving the human eye, but extended to the ultraviolet and infrared ends. From the Roque de los Muchachos Observatory (Garafía, La Palma), this instrument has been responsible for the discovery of this galactic population, whose analysis could change our current knowledge about the formation and evolution of galaxies.

The OTELO project involves researchers from various institutions in Spain (Institute of Astrophysics of the Canary Islands Institute of Astrophysics of Andalusia-CSIC, IFCA-University of Cantabria, Center for Astrobiology (INTA-CSIC), ISDEFE and Universidad Complutense de Madrid) and other countries (Mexico, ESO-Chile, Denmark, Canada and Australia).

It has been funded by the Ministry of Economy and Competitiveness (MINECO) through projects AYA2013-46724-P, AYA2014-58861-C3-1-P, AYA2014-58861-C3-2-P, AYA2014-58861-C3-3- P, AYA2016-75808-R, AYA2016-75931-C2-2-P, AYA2017-88007-C3-1-P and AYA2017-88007-C3-2-P.

Article: The OTELO survey: I. Presentation, multiwavelength data reduction and catalog, The OTELO survey: II. The impact of Tunable narrow band Filters in surveys,

Contact the IAC: Jordi Cepa ( )

Science article
OTELO reveals a population of “ghost galaxies” in the Universe
Sep. 10, 2018

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
The Centro de Astrofísica en La Palma (CALP)
The Observatorio del Teide (OT), in Izaña (Tenerife).
The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, at an altitude of 2,396 m (7,861 ft)

These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

The IAC’s research programme includes astrophysical research and technological development projects.

The IAC is also involved in researcher training, university teaching and outreachactivities.

The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC