Energy News  
STELLAR CHEMISTRY
Unraveling formation time-scales of galactic bulges
by Staff Writers
Lisbon, Portugal (SPX) Apr 14, 2020

Artist's impression of an active galaxy that has jets.

Using data from the CALIFA1 Integral Field Spectroscopy (IFS2) survey and advanced modeling tools, researchers from Instituto de Astrofisica e Ciencias do Espaco (IA3) have obtained important results about the central spherical component (the bulge) in spiral galaxies like the Milky Way, shedding new light on our understanding of galactic evolution. The result was published in the latest issue of Astronomy and Astrophysics4.

It took several years and a lot of computational power to analyze approximately half a million spectra from a sample that covers all morphological types of non-interacting spiral galaxies. The team5 was able to measure, for the first time, the age variation of the stars in the bulge, from the center to the periphery, and understand the way this age difference relates to other galaxy properties, like the existence of Active Galactic Nuclei6 (AGN) or the total mass of stars in the galaxy.

This work revealed that the stellar population at the center of the most massive spiral galaxies is older than the stars at the edge of the bulge, while in low mass galaxies the opposite happens - the youngest stars populate the center of the bulge, and the older are in the periphery.

This result is in agreement with a previous study by the team, which had already found strong evidence for a unified scenario for the formation of spiral galaxies. Contrary to what is established, low and high mass spiral galaxies appear to be formed in the same manner, although high mass galaxies pass the same formation stages earlier and quicker than their lower mass counterparts.

These measurements can be used to estimate the impact of an AGN, on bulge (and therefore galactic) evolution. The fact that the mass of a bulge is tightly connected to that of the super massive black hole that powers the AGN, points to an intimate physical link between the growth of galaxies and their super massive black holes. Understanding bulge formation and evolution is therefore indispensable for the understanding of how super massive black holes were born in the Era of Reionization7 and how they influenced the evolution of galaxies.

According to IA researcher Iris Breda, the leading author of the paper: "There are many important lessons one can take from our study, the most relevant one being that bulges that are hosted by massive spiral galaxies cannot have formed in a quick and violent star-formation episode as it is commonly thought. To the contrary, these results support a scenario where these bulges are formed gradually within 2 to 4 billions of years."

Breda, who developed most of this work during her recently finished PhD at IA and the Science Faculty of the University of Porto, concludes: "Together with our previous results, our recent study lends support to the hypothesis that the least massive galaxies, which are now actively forming stars in the very center of their bulges, currently resemble a scaled-down version of the most massive spiral galaxies at their early evolutionary stages."

To FCT investigator Polychronis Papaderos, leader of the thematic line The assembly history of galaxies resolved in space and time at IA: "An AGN evacuates the bulge from cold gas, therefore shuts off star formation, first in its central part and, as time progresses, also in its periphery.

This phenomenon results in a decrease in the mean age of stellar populations as we move from the center to the periphery of the bulge. By taking advantage of this fact, we invented a method to estimate the average velocity for the inside-out star formation quenching driven by the AGN. The relatively low velocity we infer (1-2 km/s) implies that the rise of AGN activity does not lead to a catastrophic episode of sudden removal of gas and an abrupt termination of star formation throughout the bulge."

The leading participation of IA's team in radio surveys, such as the "Evolutionary Map of the Universe" (EMU), offers ideal conditions for an unprecedented detailed study of the interaction of AGN with the ambient gas in galactic nuclei through deep radio-interferometry. This will allow them to look for small-scale radio-jets in bulges, which they believe went undetected from previous low-resolution radio interferometry observations.

The study of AGN activity since the Era of Reionization and its impact on galaxy evolution constitutes one of the main axes of research at IA.

To IA coordinator Jose Afonso (IA and Science Faculty of the University of Lisbon): "The finer details of galaxy formation and evolution are finally being explored, aligning unprecedented observations with revolutionary computational tools and modelling. These techniques will soon be taken to the next level, as we will be installing a new, powerful spectrograph, MOONS, at ESO's Very Large Telescope. We will then have access to detailed observations of millions of galaxies during the heyday of galaxy evolution in the Universe, when the Universe was less than half its current age. IA researchers will be there, exploring those new observations and helping to better understand the assembly history of galaxies."

Research Report: "Stellar age gradients and inside-out star formation quenching in galaxy bulges"


Related Links
Instituto de Astrofisica e Ciencias do Espaco
Stellar Chemistry, The Universe And All Within It


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


STELLAR CHEMISTRY
Beyond the Brim, Sombrero galaxy's halo suggests turbulent past
Baltimore MD (SPX) Feb 21, 2020
Surprising new data from NASA's Hubble Space Telescope suggests the smooth, settled "brim" of the Sombrero galaxy's disk may be concealing a turbulent past. Hubble's sharpness and sensitivity resolves tens of thousands of individual stars in the Sombrero's vast, extended halo, the region beyond a galaxy's central portion, typically made of older stars. These latest observations of the Sombrero are turning conventional theory on its head, showing only a tiny fraction of older, metal-poor stars in t ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

STELLAR CHEMISTRY
Brussels tries to inoculate EU Green Deal against virus

Uncertain climate future could disrupt energy systems

Smaller scale solutions needed for rapid progress towards emissions targets

Brussels not dropping Green Deal despite virus

STELLAR CHEMISTRY
USC scientists develop a better redox flow battery

Clean Power Alliance signs large-scale 100MW battery Energy Storage Agreement

Scientists tap unused energy source to power smart sensor networks

Scientists see energy gap modulations in a cuprate superconductor

STELLAR CHEMISTRY
Opportunity blows for offshore wind in China

Alphabet cuts cord on power-generating kite business

Iberdrola will build its next wind farm in Spain with the most powerful wind turbine

UK looks to offshore wind for green energy transition

STELLAR CHEMISTRY
Azuri helping off-grid kids across Kenya continue classes while schools closed

Longroad Energy completes financing for 215 MWdc Little Bear Solar Projects

Eindhoven researchers present revolutionary light-emitting silicon

Next gen solar cells perform better when there's a camera around

STELLAR CHEMISTRY
Framatome to deliver reactor protection system to Kursk Nuclear Power Plant II in Russia

Framatome earns high safety marks from US nuclear commission

Framatome opens new research and operations center and expands Intercontrole in Cadarache, France

Visual inspection in nuclear environments

STELLAR CHEMISTRY
Making biofuels cheaper by putting plants to work

A novel biofuel system for hydrogen production from biomass

Recovering phosphorus from corn ethanol production can help reduce groundwater pollution

Deceptively simple process could boost plastics recycling

STELLAR CHEMISTRY
Top oil producers except Mexico agree to output cuts: OPEC

OPEC, allies consider output cut after price crash

G20 ministers vow to calm oil markets but quiet on output cuts

Oil prices rebound on hopes for output cut deal

STELLAR CHEMISTRY
Brazil, US 'rolling back' on climate: UN rights chief

March 2020 among hottest on record: EU

Coronavirus having little impact on climate; COP26 postponed

The right dose of geoengineering could reduce climate change risks









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.