Supermassive black holes and nuclear stellar disks, nuclear keys to galaxy formation and evolution
Lead Research Organisation:
University of Hertfordshire
Department Name: Science and Technology RI
Abstract
Like the pieces of a Cosmic Jigsaw, galaxies come in different shapes and colours. Understanding how galaxies evolved their present-day properties is one of the most important and longstanding issues in astronomy. Among the scientists in this field, common wisdom has it that galaxies formed from a combination of star-formation episodes, during which gas turns into young blue stars, and merging events, whereby galaxies collide and reassemble into different galactic configurations. If galaxies formed all at once, they would only become redder as their stellar population ages, without changing their shape. Whereas the star-formation history of galaxies has been measured by many observations, the pace at which galaxies merge through cosmic times remains largely unknown. In this respect, astronomers are left only with the predictions of their models. According to the widely accepted model of a Universe dominated by cold dark matter, because galaxies grow in mass over time by merging together, the largest galaxies have assembled just recently, whereas the smallest galaxies were already in place early on in the history of the Universe. Furthermore, galaxies in groups or clusters should have assembled before their counterparts in less densely populated environments. Galaxies can indeed find it difficult to merge once they crowd together. This is because they tend to swing by each other too fast for them to coalesce. As an Advanced Fellow I will test these theoretical predictions. For this investigation I will adopt as a record of the time when galaxies merged together the age of the stars in the small disks that are often found in the centre of galaxies. Numerical simulations show that such nuclear disks are easily destroyed when galaxies collides, so that their presence in a given galaxy indicates that no such a catastrophic event occurred since the disk formed. If the cold dark matter model is correct, I should find that nuclear disks are made of older stars in smaller galaxies, or in those living in the most crowded galactic environments. By the turn of the century, another puzzling component of galaxies turned out to have a key role in galaxy formation and evolution: Supermassive Black Holes. Once considered by astronomers only as a theoretical possibility, supermassive black holes have now been found to lurk at the center of many galaxies, including our Milky Way. Most importantly, the mass of the central black holes appears to scale with the mass of their host galaxies, or only to that of the bulge component of disk galaxies. Roughly speaking, central black holes have been found to be almost one thousand times less massive than their host galaxy or bulge. This striking coincidence between objects that are vastly different in size, with supermassive black holes extending at most to the size of our Solar system, strongly suggests that the evolution of supermassive black holes and galaxies is intimately related. The universality of this relationship, however, is not yet established. This is because the mass of supermassive black holes has been measured only in a limited number of galaxies, and almost exclusively in certain kinds. It would be surprising if galaxies that formed in different ways were found to share the same black-hole mass content. As an Advanced Fellow, I will complete the demography of supermassive black holes using large ground-based telescopes that can correct for the atmospheric blurring with the aid of bright reference stars or point sources created in the upper atmosphere by powerful lasers. This will allow me to measure the mass of supermassive black holes as if I were using the Hubble space telescope, and to observe precisely those galaxies for which there are very few black-hole mass measurements. Using these new data I will test the universality of the relationship between supermassive black holes and galaxies, and shed more light on the nature of this link.
People |
ORCID iD |
| Marc Sarzi (Principal Investigator / Fellow) |
Publications
Alatalo K
(2013)
The ATLAS3D project - XVIII. CARMA CO imaging survey of early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Alatalo K
(2013)
NGC 1266 AS A LOCAL CANDIDATE FOR RAPID CESSATION OF STAR FORMATION
in The Astrophysical Journal
Alatalo K
(2011)
DISCOVERY OF AN ACTIVE GALACTIC NUCLEUS DRIVEN MOLECULAR OUTFLOW IN THE LOCAL EARLY-TYPE GALAXY NGC 1266
in The Astrophysical Journal
Baes M
(2014)
An extremely low gas-to-dust ratio in the dust-lane lenticular galaxy NGC 5485?
in Monthly Notices of the Royal Astronomical Society: Letters
Bayet E
(2013)
The ATLAS3D project - XVI. Physical parameters and spectral line energy distributions of the molecular gas in gas-rich early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Beifiori A
(2009)
UPPER LIMITS ON THE MASSES OF 105 SUPERMASSIVE BLACK HOLES FROM HUBBLE SPACE TELESCOPE /SPACE TELESCOPE IMAGING SPECTROGRAPH ARCHIVAL DATA
in The Astrophysical Journal
Bois M
(2011)
The ATLAS3D project - VI. Simulations of binary galaxy mergers and the link with fast rotators, slow rotators and kinematically distinct cores The ATLAS3D project - VI. Binary galaxy mergers
in Monthly Notices of the Royal Astronomical Society
Bois M
(2010)
Formation of slowly rotating early-type galaxies via major mergers: a resolution study Formation of slowly rotating early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Bontà E
(2009)
THE HIGH-MASS END OF THE BLACK HOLE MASS FUNCTION: MASS ESTIMATES IN BRIGHTEST CLUSTER GALAXIES
in The Astrophysical Journal
Bureau M
(2011)
The SAURON project - XVIII. The integrated UV-line-strength relations of early-type galaxies The SAURON project - XVIII
in Monthly Notices of the Royal Astronomical Society
Cappellari M
(2012)
Systematic variation of the stellar initial mass function in early-type galaxies.
in Nature
Cappellari M
(2013)
The ATLAS3D project - XV. Benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, Fundamental Plane and Mass Plane
in Monthly Notices of the Royal Astronomical Society
Cappellari M
(2013)
The ATLAS3D project - XX. Mass-size and mass-s distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function
in Monthly Notices of the Royal Astronomical Society
Cappellari M
(2011)
The ATLAS3D project - VII. A new look at the morphology of nearby galaxies: the kinematic morphology-density relation The ATLAS3D project - VII. Morphology-density
in Monthly Notices of the Royal Astronomical Society
Cappellari M
(2011)
The ATLAS3D project - I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria The ATLAS3D project - I. The sample
in Monthly Notices of the Royal Astronomical Society
Cardamone C
(2009)
Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies
in Monthly Notices of the Royal Astronomical Society
Crocker A
(2012)
The ATLAS 3D project - XI. Dense molecular gas properties of CO-luminous early-type galaxies ? The ATLAS 3D project - XI. Dense molecular gas
in Monthly Notices of the Royal Astronomical Society
Darg D
(2010)
Galaxy Zoo: the properties of merging galaxies in the nearby Universe - local environments, colours, masses, star formation rates and AGN activity
in Monthly Notices of the Royal Astronomical Society
Darg D
(2010)
Galaxy Zoo: the fraction of merging galaxies in the SDSS and their morphologies
in Monthly Notices of the Royal Astronomical Society
Davis T
(2013)
The ATLAS3D Project - XIV. The extent and kinematics of the molecular gas in early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Davis T
(2011)
The ATLAS3D project - V. The CO Tully-Fisher relation of early-type galaxies The CO-TFR of early-type galaxies
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
(2012)
Gemini GMOS and WHT SAURON integral-field spectrograph observations of the AGN-driven outflow in NGC 1266 IFU observations of the outflow in NGC 1266
in Monthly Notices of the Royal Astronomical Society
Davis T
(2011)
The ATLAS3D project - X. On the origin of the molecular and ionized gas in early-type galaxies On the origin of gas in early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Davis TA
(2013)
A black-hole mass measurement from molecular gas kinematics in NGC4526.
in Nature
Duc P
(2015)
The ATLAS3D project - XXIX. The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
in Monthly Notices of the Royal Astronomical Society
Duc P
(2011)
The ATLAS3D project - IX. The merger origin of a fast- and a slow-rotating early-type galaxy revealed with deep optical imaging: first results The merger origin of NGC 680 and 5557
in Monthly Notices of the Royal Astronomical Society
Emsellem E
(2014)
A kinematically distinct core and minor-axis rotation: the MUSE perspective on M87
in Monthly Notices of the Royal Astronomical Society: Letters
Emsellem E
(2011)
The ATLAS3D project - III. A census of the stellar angular momentum within the effective radius of early-type galaxies: unveiling the distribution of fast and slow rotators Census of the stellar angular momentum in ETGs
in Monthly Notices of the Royal Astronomical Society
Falcón-Barroso J
(2011)
The SAURON project - XIX. Optical and near-infrared scaling relations of nearby elliptical, lenticular and Sa galaxies The SAURON project - XIX
in Monthly Notices of the Royal Astronomical Society
Jeong H
(2009)
The SAURON project - XIII. SAURON-GALEX study of early-type galaxies: the ultraviolet colour-magnitude relations and Fundamental Planes
in Monthly Notices of the Royal Astronomical Society
Jeong H
(2013)
ON THE NATURE OF SODIUM EXCESS OBJECTS. I. DATA AND OBSERVED TRENDS
in The Astrophysical Journal Supplement Series
Jeong H
(2012)
The SAURON project - XXI. The spatially resolved UV-line strength relations of early-type galaxies The SAURON project - XXI
in Monthly Notices of the Royal Astronomical Society
Johansson J
(2014)
Diffuse gas in galaxies sheds new light on the origin of Type Ia supernovae
in Monthly Notices of the Royal Astronomical Society
Khochfar S
(2011)
The ATLAS3D project - VIII. Modelling the formation and evolution of fast and slow rotator early-type galaxies within ?CDM Fast and slow rotators
in Monthly Notices of the Royal Astronomical Society
Krajnovic D
(2013)
The ATLAS3D Project - XXIII. Angular momentum and nuclear surface brightness profiles
in Monthly Notices of the Royal Astronomical Society
Krajnovic D
(2011)
The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies Morphologies, kinematics and alignment
in Monthly Notices of the Royal Astronomical Society
Krajnovic D
(2008)
The SAURON project - XII. Kinematic substructures in early-type galaxies: evidence for discs in fast rotators
in Monthly Notices of the Royal Astronomical Society
Krajnovic D
(2013)
The ATLAS3D project - XVII. Linking photometric and kinematic signatures of stellar discs in early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Kuntschner H
(2010)
The SAURON project - XVII. Stellar population analysis of the absorption line strength maps of 48 early-type galaxies The SAURON project - XVII
in Monthly Notices of the Royal Astronomical Society
Lablanche P
(2012)
The ATLAS project - XII. Recovery of the mass-to-light ratio of simulated early-type barred galaxies with axisymmetric dynamical models The ATLAS3D project - XII. M/L recovery
in Monthly Notices of the Royal Astronomical Society
Ledo H
(2010)
A census of nuclear stellar discs in early-type galaxies Nuclear stellar discs in early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Martig M
(2013)
The ATLAS3D project - XXII. Low-efficiency star formation in early-type galaxies: hydrodynamic models and observations
in Monthly Notices of the Royal Astronomical Society
McDermid R
(2014)
CONNECTION BETWEEN DYNAMICALLY DERIVED INITIAL MASS FUNCTION NORMALIZATION AND STELLAR POPULATION PARAMETERS
in The Astrophysical Journal
McDermid R
(2015)
The ATLAS3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Morelli L
(2010)
Multiband photometric decomposition of nuclear stellar disks
in Astronomy and Astrophysics
Naab T
(2014)
The ATLAS3D project - XXV. Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators
in Monthly Notices of the Royal Astronomical Society
Nyland K
(2016)
The atlas 3D Project - XXXI. Nuclear radio emission in nearby early-type galaxies
in Monthly Notices of the Royal Astronomical Society
Oh K
(2011)
IMPROVED AND QUALITY-ASSESSED EMISSION AND ABSORPTION LINE MEASUREMENTS IN SLOAN DIGITAL SKY SURVEY GALAXIES
in The Astrophysical Journal Supplement Series
Oosterloo T
(2010)
Early-type galaxies in different environments: an H i view Early-type galaxies in different environments
in Monthly Notices of the Royal Astronomical Society
| Description | There were several key findings from this grant. On Nuclear Stellar disks I eventually published papers demonstrating both their fragility and that their stellar age can be measured with high precision (Sarzi et al. 2015, 2016b). This allows therefore to use them as robust clocks for the assembly history of their host galaxies. During my fellowship I also explored further the nature of the ionised- and hot-gas in early type galaxies. In the first case I found that hot UV-bright stars are most likely responsible for ionising their case (Sarzi et al. 2010), whereas in the latter I found that the hot-gas content of early-type galaxies correlates with the degree of rotational support of these systems (Sarzi et al. 2013), in the sense that fast-rotating galaxies are less capable of retaining their hot gas. Related to the ionised-gas emission of early-type galaxies, I have also investigated the presence of the prime stellar candidates for powering such a nebular emission, and that is post-Asymptotic Red Giant branch (pAGB) stars, which are also known as the central stars of Planetary Nebulae (PNe). In this respect, in Sarzi et al. (2011) I have demonstrated for the first time that Integral-Field Spectroscopic data allow to detect PNe in the optical region of early-type galaxies - where the ionised-gas emission is observed. Furthermore, in Pastorello, Sarzi et al. (2013) I have found that the brightest PNe could be notably absent in metal-rich environment such as galactic nuclei and the most massive early-type galaxies, which in turn may go back to pose some problem for powering the nebular emission of early-type galaxies with pAGB stars. |
| Exploitation Route | I would hope that my results on Nuclear Stellar Disk (NSD) would set the basis for using these common sub-components in galaxies to help constraining more directly the assembly history of galaxies. Similarly, my work on PNes should provide some more constraints on our understanding of the late stages of stellar evolution, in particular in galactic environments unlike that of the Milky Way. Most recently the scietific justification for the part of this project concenrning NSDs has led to the award of an Erasmus+ student fellowship that allowed an MSc student (Andrea Incatasciato, working under the co-supervision of my colleague Massimo Dotti at Milano Bicocca) to work for six months on tailoring our numerical assessement for the fragility of NSDs at specific galaxies with state-of-the-art MUSE integral-field spectroscopic data. The results of this work should be published within the next year. |
| Sectors | Education,Other |
| Description | STFC Public Engagement Fellowship |
| Amount | £120,000 (GBP) |
| Organisation | Science and Technologies Facilities Council (STFC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 09/2014 |
| End | 10/2016 |
| Title | The GandALF spectral fitting code |
| Description | During my award I had the time to perfect my GandALF fitting code, which I released in 2007 (before my award) and which is now fairly commonly used to analyse the optical spectra of galaxies. More specifically GandALF (Gas and Absorption Line Fitting) allows to simultaneously describe the nebular and stellar parts of the optical spectra of external galaxies. |
| Type Of Material | Data analysis technique |
| Year Produced | 2007 |
| Provided To Others? | Yes |
| Impact | The code has now be used in over 100 refereed publications. A list of these publications (to May 2014) can be found at this link http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?library&libname=Gandalf+papers&libid=46e126f2ad |
| URL | http://star.herts.ac.uk/~sarzi/PaperV_nutshell/PaperV_nutshell.html |
| Description | Yonsei collaboration |
| Organisation | Yonsei University |
| Country | Korea, Republic of |
| Sector | Academic/University |
| PI Contribution | This is a collaboration with the group of Prof. Sukyoung Yi, at Yonsei University in Seoul. Much of my travel support from my STFC fellowship has been used to foster this collaboration, which most notably use the SDSS spectroscopic database to extract with my code "Gandalf" the basic properties of more than 600,000 galaxies within a redshift of 0.2. |
| Impact | At the moment, the most important output of this work, a complete catalogue of spectral measurements based on my "Gandalf" code for the entire SDSS-DR7 spectroscopic release, is being reviewed for publication on ApJ. We expect this paper to be published by 2011. |
| Start Year | 2009 |
| Description | Invited Speaker at the 2013 Norvegian Astronomy Society conference |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Type Of Presentation | Keynote/Invited Speaker |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Similar to the London Astrofest, I was invited to give a talk on the subject of Supermassive Black Hole, in Tromso, Norway A talk |
| Year(s) Of Engagement Activity | 2013 |
| Description | Invited Speaker at the London Astrofest 2012 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Type Of Presentation | Keynote/Invited Speaker |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | I was a plenary speaker at the London Astrofest, which is the biggest conference for Astronomy and Space Science enthusiasts, which takes place every year in Kensington, London. I gave a talk on the subject of Supermassive Black Holes |
| Year(s) Of Engagement Activity | 2012 |
| Description | Main Organiser of the Open Night at the Bayfordbury Observatory (since 2009) |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Since October 2009, I am the main organiser of the Open Night events that the Centre for Astrophysics Research organises at the Bayfordbury Observatory of the University of Hertfordshire. During such event, our guest can visit our optical and radio telescope, enjoy our Planetarium and partecipate in a number of lab and computer activities. Over the year, I have expanded the scope of these events, which are now routinely fully booked and see around 400 visitors per open night. With 5-6 events per year, this means that we reach more than 2000 visitors per year. |
| Year(s) Of Engagement Activity | 2009,2010,2011,2012,2013,2014 |
| Description | Radio Interviews on BBC Three Counties Radio (2013, 14) |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | On January 9, 2013 I was briefly interviewed by Roberto Perrone on BBC Three Counties Radio to describe the program of our Bayfordbury Open Night on that same day. Such an Open Night was indeed part of the BBC Stargazing activities that were promoted by the BBC during the months of January and February 2013. On March 24, 2014 I was briefly interviewed by Roberto Perrone on BBC Three Counties Radio to describe the program of our Bayfordbury Open Night, and in particular to talk about our special Art & Astronomy event, on the previous friday the 21st. This interviews certainly generated a great deal of publicity for our Open Night program at Bayfordbury, which are usually fully booked. |
| Year(s) Of Engagement Activity | 2013,2014 |