The cycle of life, death and rebirth in massive early-type galaxies; star formation, black-holes and feedback
Lead Research Organisation:
University of Hertfordshire
Department Name: Science and Technology RI
Abstract
My research focuses on understanding the biggest galaxies that exist around us in the local universe. These objects are interesting because they are thought to be the end point of galaxy evolution. They are made up of billions of old stars, have red optical colours, and are generally thought to be free of cold gas - the fuel for new stars. Thus they are often described as "red and dead". Astronomers still don't fully know what caused these galaxies to die off, or if they can come back to life again. It is these processes that I am investigating.
One of the ways astronomers think these massive galaxies become "red and dead" is due to the supermassive black-holes that lie at their cores. These enigmatic objects are clearly linked to galaxy formation, as they seem to grow in step with their galaxy host. In order to understand the role of black holes in the formation of galaxies, I developed a new technique to measure their masses, by tracing the motions of molecular gas clouds swirling around them. This technique is exciting, because it opens up the possibility of measuring black hole masses more accurately, and in more galaxies than ever before. As part of my Rutherford fellowship I aim to use this technique to reveal the dark monsters lurking at the hearts of nearby galaxies.
When black holes swallow matter they emit large amounts of high energy light, and can accelerate large jets of particles. Both of these processes can affect gas clouds, throwing them out of galaxies. These outflows are one mechanism that can help form the gas-poor massive galaxies I study. A few years ago I helped identify one of the nearest examples of a black hole expelling large amounts of gas in this way. During my Rutherford fellowship I will use the chemistry of the gas in this outflow to determine whether it is the extremely strong light from the black hole, or the jet of particles that is causing the outflow we see. This will give us one more piece of the puzzle, helping to explain why most massive galaxies with big black holes are gas poor.
Massive galaxies, like the ones I study, don't have to stay "red and dead". The can come back to life if material from dying stars can cool and become fuel for a new generation of stars. They can also merge with other small galaxies and steal their fuel. Around 1/4 of the massive "red and dead" galaxies around us today are currently in the process of being reborn. Understanding which process causes this, and what effect surrounding galaxies have, will allow us to determine whether these galaxies are destined to fail and go back to being "red and dead", or if they can eventually come back to life fully.
I have discovered that these objects that have obtained fuel for star-formation, don't seem to be using it very effectively. They are very inefficient at forming stars when compared to galaxies like our own Milky Way. I aim to find out why this is happening, and what this can tell us about the physics controlling star formation in the universe.
One of the ways astronomers think these massive galaxies become "red and dead" is due to the supermassive black-holes that lie at their cores. These enigmatic objects are clearly linked to galaxy formation, as they seem to grow in step with their galaxy host. In order to understand the role of black holes in the formation of galaxies, I developed a new technique to measure their masses, by tracing the motions of molecular gas clouds swirling around them. This technique is exciting, because it opens up the possibility of measuring black hole masses more accurately, and in more galaxies than ever before. As part of my Rutherford fellowship I aim to use this technique to reveal the dark monsters lurking at the hearts of nearby galaxies.
When black holes swallow matter they emit large amounts of high energy light, and can accelerate large jets of particles. Both of these processes can affect gas clouds, throwing them out of galaxies. These outflows are one mechanism that can help form the gas-poor massive galaxies I study. A few years ago I helped identify one of the nearest examples of a black hole expelling large amounts of gas in this way. During my Rutherford fellowship I will use the chemistry of the gas in this outflow to determine whether it is the extremely strong light from the black hole, or the jet of particles that is causing the outflow we see. This will give us one more piece of the puzzle, helping to explain why most massive galaxies with big black holes are gas poor.
Massive galaxies, like the ones I study, don't have to stay "red and dead". The can come back to life if material from dying stars can cool and become fuel for a new generation of stars. They can also merge with other small galaxies and steal their fuel. Around 1/4 of the massive "red and dead" galaxies around us today are currently in the process of being reborn. Understanding which process causes this, and what effect surrounding galaxies have, will allow us to determine whether these galaxies are destined to fail and go back to being "red and dead", or if they can eventually come back to life fully.
I have discovered that these objects that have obtained fuel for star-formation, don't seem to be using it very effectively. They are very inefficient at forming stars when compared to galaxies like our own Milky Way. I aim to find out why this is happening, and what this can tell us about the physics controlling star formation in the universe.
Organisations
- University of Hertfordshire (Lead Research Organisation)
- NRC Herzberg Institute of Astrophysics (NRC-HIA) (Collaboration)
- European Southern Observatory (ESO) (Collaboration)
- Graduate University for Advanced Studies (SOKENDAI), Okazaki (Collaboration)
- University of Hertfordshire (Collaboration)
- UNIVERSITY OF OXFORD (Collaboration)
- Princeton University (Collaboration)
- Max Planck Society (Collaboration)
- University of Cologne (Collaboration)
- University of California, Berkeley (Collaboration)
- Leibniz Association (Collaboration)
- Observatory of Paris (Collaboration)
- CARDIFF UNIVERSITY (Fellow)
Publications
Agius N
(2015)
H-ATLAS/GAMA and HeViCS - dusty early-type galaxies in different environments
in Monthly Notices of the Royal Astronomical Society
Alatalo K
(2014)
SUPPRESSION OF STAR FORMATION IN NGC 1266
in The Astrophysical Journal
Alatalo K
(2013)
NGC 1266 AS A LOCAL CANDIDATE FOR RAPID CESSATION OF STAR FORMATION
in The Astrophysical Journal
Alatalo K
(2015)
Evidence of boosted 13CO/12CO ratio in early-type galaxies in dense environments
in Monthly Notices of the Royal Astronomical Society
Davis T
(2014)
Systematic variation of the 12CO/13CO ratio as a function of star formation rate surface density
in Monthly Notices of the Royal Astronomical Society
Davis T
(2015)
The MASSIVE survey - III. Molecular gas and a broken Tully-Fisher relation in the most massive early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Davis T
(2017)
Spatially resolved variations of the IMF mass normalization in early-type galaxies as probed by molecular gas kinematics
in Monthly Notices of the Royal Astronomical Society
Davis T
(2014)
A figure of merit for black hole mass measurements with molecular gas
in Monthly Notices of the Royal Astronomical Society
Davis T
(2014)
The ATLAS3D Project - XXVIII. Dynamically driven star formation suppression in early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Davis T
(2015)
Molecular and atomic gas in dust lane early-type galaxies - I. Low star formation efficiencies in minor merger remnants
in Monthly Notices of the Royal Astronomical Society
Description | In this reporting period I discovered that the most massive galaxies in our universe have the same amount of cold gas as their lower mass compatriots. This gas appears to be primarily accreted from external sources, form stars very slowly, and takes a long time to relax into the galaxy potential. |
Exploitation Route | These findings are instrumental in understanding the evolution of the most massive galaxies in our universe, and their future evolution. This will allow future large surveys (such as SAMI and MANGA) to constrain the gas rich merger rate in the local universe, which is directly related to the LCDM model. |
Sectors | Other |
Title | KinMS_mcmc |
Description | Linking the KinMS tools to an MCMC wrapper to better fit SMBH masses as part of the WISDOM project |
Type Of Material | Data analysis technique |
Year Produced | 2014 |
Provided To Others? | Yes |
Impact | The model has been used by various other groups working in this field. |
URL | https://github.com/TimothyADavis/KinMS |
Description | CARS |
Organisation | European Southern Observatory (ESO) |
Country | Germany |
Sector | Charity/Non Profit |
PI Contribution | I lead the molecular followup of CARS sources, especially those with outflows. |
Collaborator Contribution | The other team members deal with the MUSE IFU data that forms the basis of the survey, and the ancillary data (radio, X-ray, etc). |
Impact | First papers incoming shortly. |
Start Year | 2015 |
Description | CARS |
Organisation | Leibniz Association |
Department | Leibniz Institute for Astrophysics Potsdam |
Country | Germany |
Sector | Academic/University |
PI Contribution | I lead the molecular followup of CARS sources, especially those with outflows. |
Collaborator Contribution | The other team members deal with the MUSE IFU data that forms the basis of the survey, and the ancillary data (radio, X-ray, etc). |
Impact | First papers incoming shortly. |
Start Year | 2015 |
Description | CARS |
Organisation | Observatory of Paris |
Country | France |
Sector | Academic/University |
PI Contribution | I lead the molecular followup of CARS sources, especially those with outflows. |
Collaborator Contribution | The other team members deal with the MUSE IFU data that forms the basis of the survey, and the ancillary data (radio, X-ray, etc). |
Impact | First papers incoming shortly. |
Start Year | 2015 |
Description | CARS |
Organisation | University of Cologne |
Department | Department of Physics |
Country | Germany |
Sector | Academic/University |
PI Contribution | I lead the molecular followup of CARS sources, especially those with outflows. |
Collaborator Contribution | The other team members deal with the MUSE IFU data that forms the basis of the survey, and the ancillary data (radio, X-ray, etc). |
Impact | First papers incoming shortly. |
Start Year | 2015 |
Description | CARS |
Organisation | University of Cologne |
Department | Department of Physics |
Country | Germany |
Sector | Academic/University |
PI Contribution | I lead the molecular followup of CARS sources, especially those with outflows. |
Collaborator Contribution | The other team members deal with the MUSE IFU data that forms the basis of the survey, and the ancillary data (radio, X-ray, etc). |
Impact | First papers incoming shortly. |
Start Year | 2015 |
Description | MASSIVE |
Organisation | Max Planck Society |
Department | Max Planck Institute For Extraterrestrial Physics (MPE) |
Country | Germany |
Sector | Academic/University |
PI Contribution | I lead the molecular gas aspects of the survey, providing crucial information on the cold phases of the ISM in the most massive galaxies in our universe. |
Collaborator Contribution | UCB and Princeton staff members primarily supplied the optical IFU information that the survey is based on, while other members provided analysis and ancillary data sets. |
Impact | 10.1088/0004-637X/795/2/158 10.1088/0004-637X/807/1/11 10.1093/mnras/stv2313 |
Start Year | 2014 |
Description | MASSIVE |
Organisation | NRC Herzberg Institute of Astrophysics (NRC-HIA) |
Country | Canada |
Sector | Academic/University |
PI Contribution | I lead the molecular gas aspects of the survey, providing crucial information on the cold phases of the ISM in the most massive galaxies in our universe. |
Collaborator Contribution | UCB and Princeton staff members primarily supplied the optical IFU information that the survey is based on, while other members provided analysis and ancillary data sets. |
Impact | 10.1088/0004-637X/795/2/158 10.1088/0004-637X/807/1/11 10.1093/mnras/stv2313 |
Start Year | 2014 |
Description | MASSIVE |
Organisation | Princeton University |
Department | Department of Astrophysical Sciences |
Country | United States |
Sector | Academic/University |
PI Contribution | I lead the molecular gas aspects of the survey, providing crucial information on the cold phases of the ISM in the most massive galaxies in our universe. |
Collaborator Contribution | UCB and Princeton staff members primarily supplied the optical IFU information that the survey is based on, while other members provided analysis and ancillary data sets. |
Impact | 10.1088/0004-637X/795/2/158 10.1088/0004-637X/807/1/11 10.1093/mnras/stv2313 |
Start Year | 2014 |
Description | MASSIVE |
Organisation | University of California, Berkeley |
Department | Department of Astronomy |
Country | United States |
Sector | Academic/University |
PI Contribution | I lead the molecular gas aspects of the survey, providing crucial information on the cold phases of the ISM in the most massive galaxies in our universe. |
Collaborator Contribution | UCB and Princeton staff members primarily supplied the optical IFU information that the survey is based on, while other members provided analysis and ancillary data sets. |
Impact | 10.1088/0004-637X/795/2/158 10.1088/0004-637X/807/1/11 10.1093/mnras/stv2313 |
Start Year | 2014 |
Description | WISDOM |
Organisation | Graduate University for Advanced Studies (SOKENDAI), Okazaki |
Country | Japan |
Sector | Academic/University |
PI Contribution | I co-lead the team, overseeing strategy, coordinating observing applications and distributing the workload. |
Collaborator Contribution | The other partners provide expertise, and work on the outputs of the observational program. Some of the research outputs are also being lead from these other institutes. |
Impact | A figure of merit for black hole mass measurements with molecular gas, MNRAS, 2014, Volume 443, Issue 1, p.911-918 A black-hole mass measurement from molecular gas kinematics in NGC4526. Nature, 2013, 494, 328-330 |
Start Year | 2013 |
Description | WISDOM |
Organisation | University of California, Berkeley |
Department | Department of Astronomy |
Country | United States |
Sector | Academic/University |
PI Contribution | I co-lead the team, overseeing strategy, coordinating observing applications and distributing the workload. |
Collaborator Contribution | The other partners provide expertise, and work on the outputs of the observational program. Some of the research outputs are also being lead from these other institutes. |
Impact | A figure of merit for black hole mass measurements with molecular gas, MNRAS, 2014, Volume 443, Issue 1, p.911-918 A black-hole mass measurement from molecular gas kinematics in NGC4526. Nature, 2013, 494, 328-330 |
Start Year | 2013 |
Description | WISDOM |
Organisation | University of Hertfordshire |
Department | Centre for Astrophysics Research (CAR) |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I co-lead the team, overseeing strategy, coordinating observing applications and distributing the workload. |
Collaborator Contribution | The other partners provide expertise, and work on the outputs of the observational program. Some of the research outputs are also being lead from these other institutes. |
Impact | A figure of merit for black hole mass measurements with molecular gas, MNRAS, 2014, Volume 443, Issue 1, p.911-918 A black-hole mass measurement from molecular gas kinematics in NGC4526. Nature, 2013, 494, 328-330 |
Start Year | 2013 |
Description | WISDOM |
Organisation | University of Oxford |
Department | Department of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I co-lead the team, overseeing strategy, coordinating observing applications and distributing the workload. |
Collaborator Contribution | The other partners provide expertise, and work on the outputs of the observational program. Some of the research outputs are also being lead from these other institutes. |
Impact | A figure of merit for black hole mass measurements with molecular gas, MNRAS, 2014, Volume 443, Issue 1, p.911-918 A black-hole mass measurement from molecular gas kinematics in NGC4526. Nature, 2013, 494, 328-330 |
Start Year | 2013 |