Using gravitational lensing, EPFL researchers have actually boosted the accuracy of measuring quasar host galaxy mass, offering much deeper insights into early universe galaxy advancement and black hole formation.
A group of scientists from EPFL have discovered a technique to make use of the phenomenon of strong gravitational lensing, achieving an accuracy around 3 times remarkable to any existing strategy, to properly estimate the mass of a galaxy real estate a quasar and track its development through cosmic time.
This understanding relating to the mass of galaxies that host quasars adds to our understanding of galaxy development in the early universe, assisting in the building and construction of models for galaxy formation and great void development. The findings were recently published in the journal Nature Astronomy.
” The unprecedented precision and accuracy achieved with gravitational lensing supply a new opportunity for getting robust mass quotes in the distant Universe, where traditional techniques do not have precision and are prone to predispositions,” says EPFL astrophysicist Frédéric Courbin, senior author of the research study.
The one on the left is a brilliant quasar, within a host galaxy too dim to be observed. The brilliant item on the right is another galaxy, the main gravitational lens.” In the local Universe, we observe that the most huge galaxies likewise host the most enormous black holes at their. Gravitational lensing occasions are extremely uncommon, with one galaxy in a thousand revealing the phenomenon. Given that quasars are seen in about one every thousand galaxies a quasar acting as a lens is one in a million.
” The masses of host galaxies have actually been measured in the past, but thanks to gravitational lensing, this is the very first time that the measurement is so exact in the distant Universe,” explains Martin Millon, lead author of the research study and currently at Stanford University on an SNF grant.
Integrating gravitational lensing and quasars
A quasar is a luminous manifestation of a supermassive black hole that accretes surrounding matter, sitting at the center of a host galaxy. It is generally challenging to measure how heavy a quasars host galaxy is due to the fact that quasars are very remote things, and also due to the fact that they are so brilliant that they overshine anything within its vicinity.
Gravitational lensing enables us to compute the mass of the lensing object. Thanks to Einsteins theory of gravitation, we know how enormous objects in the foreground of the night sky– the gravitational lens– can bend light coming from background things. Resulting are strange rings of light, that are actually distortions of the background thingss light by the gravitational lens.
SDSS J0919 +2720. Credit: NASA, ESA, and F. Courbin (EPFL, Switzerland).
Courbin was cycling to the Sauverny Observatory, over a decade back, when he recognized that he could combine the 2– quasars and gravitational lensing– to measure the mass of a quasars host galaxy. For this, he needed to discover a quasar in a galaxy that likewise serves as a gravitational lens.
A handful of gravitational lensing quasars observed up until now.
The Sloan Digital Sky Survey (SDSS) database was a fantastic location to browse for gravitational lensing quasars prospects, but to be sure, Courbin had to see the lensing rings. In 2010, he and associates commissioned time on the Hubble Space Telescope to observe 4 candidates of which 3 revealed lensing. Of the three, one stood apart due to its particular gravitational lensing rings: SDSS J0919 +2720.
The HST picture of SDSS J0919 +2720 reveals 2 brilliant objects in the foreground that each function as a gravitational lens, “probably 2 galaxies in the procedure of merging,” describes Courbin. The one on the left is an intense quasar, within a host galaxy too dim to be observed. The intense things on the right is another galaxy, the primary gravitational lens. A faint object on the far left is a companion galaxy. The characteristic rings are warped light originating from a background galaxy.
Computational lens modeling to the rescue.
By thoroughly examining the gravitationally lensed rings in SDSS J0919 +2720, it is possible to determine the mass of the two bright objects … in principle. Disentangling the masses of the numerous things would have been difficult without the current development of a wavelet-based lens modeling technique by co-author Aymeric Galan, currently at the Technical University of Münich (TUM), also on an SNF grant.
” One of the greatest difficulties in astrophysics is to comprehend how a supermassive black hole types,” discusses Galan. “Knowing its mass, how it compares to its host galaxy and how it evolves through cosmic times, are what enables us to discard or confirm particular formation theories.”.
” In the local Universe, we observe that the most enormous galaxies likewise host the most enormous great voids at their center. This could recommend that the development of galaxies is regulated by the amount of energy radiated by their central great void and injected into the galaxy. To evaluate this theory, we still require to study these interactions not just locally but also in the far-off Universe”, describes Millon.
Gravitational lensing events are extremely rare, with one galaxy in a thousand unveiling the phenomenon. Since quasars are seen in about one every thousand galaxies a quasar acting as a lens is one in a million. The researchers expect to spot hundreds of these lensing quasars with the ESA-NASA mission Euclid, to be launched this summer with a Falcon-9 SpaceX rocket.
Reference: “Strong gravitational lensing by AGNs as a probe of the quasar– host relations in the far-off Universe” by Martin Millon, Frédéric Courbin, Aymeric Galan, Dominique Sluse, Xuheng Ding, Malte Tewes and S. G. Djorgovski, 1 June 2023, Nature Astronomy.DOI: 10.1038/ s41550-023-01982-2.