Dr. John Regan’s group works on trying to understand both the formation mechanisms and population demographics of massive black holes. Super massive black holes are typically defined as those with masses in excess of 1 million times the mass of the Sun. These SMBHs are found at the heart of most, if not all, galaxies and we also observe them as extremely luminous quasars out to very large distances (and equivalently redshifts). The existence of such bright and therefore massive objects at high redshift poses a significant theoretical challenge. How could such massive objects emerge so early in the lifetime of the cosmos?
Equally interesting and important – particularly with the planned launch of the LISA observatory in the mid-2030's is the existence of intermediate mass black holes (IMBHs). These are black holes typically with masses in the range 1,000 – 1,000,000 times the mass of the Sun. These objects should populate less massive (so-called dwarf galaxies) and may also be the progenitors of the SMBHs. Observations of IMBHs are difficult – IMBHs are inherently less luminous than their more massive cousins and may also be located off-nuclear i.e. they may not necessarily be located at galactic centres making their detection even more challenging. Understanding the population demographics of IMBHs is hugely important in terms of predicting merger rates for LISA and for understanding the origin of SMBHs.
Our research on cosmology and the large-scale structure of the Universe, focusses specifically on theoretical models that try to account for the properties of the observable universe, including the cosmic microwave background and galaxy clusters. In more detail our current work lies in the following areas:
- Euclid. The European Space Agency's Euclid mission, launched in July 2023, is intended to better understand dark energy and dark matter by accurately measuring the acceleration of the universe using several complementary approaches. Professor Coles is the only member of the Euclid Consortium based in Ireland. Research in this area is within the Science Working Group on Galaxy Clustering. The analysis of data from Euclid will take many years after the survey is itself completed.
- Cosmic Anomalies. The current standard cosmological model fits most currently available cosmological observations, but some of this data suggests features that may need revisions or additions to the standard model to explain them. Among the questions being addressed by this research are: is there evidence of departures from the standard model in the Planck observations of the cosmic microwave background; and how can we resolve the apparent tension between different determinations of cosmological parameters (e.g., the Hubble constant) from different data sets?
- Wave Mechanics and Large-scale Structure. This work investigates the application of an idea that involves representing the large-scale distribution of matter using a wave-mechanics, specifically using the Schrödinger-Poisson description. This approach has numerous technical advantages over the standard methods but is far less widely studied. We will be applying it to problems involving dark matter in the form of ultra-light particles as well as the problem of redshift-space distortions and velocity-density reconstruction.
Dr. Patrick Kavanagh’s group works on multi-wavelength observations of various components of the matter cycle in galaxies. The evolution of galaxies is governed by the formation of stars out of molecular clouds in the interstellar medium (ISM) which in turn act as feedback engines that shape the ISM through their mechanical and radiative output, and chemically enrich the ISM over cosmic time. Active research areas and technical activities in the group are:
- Massive stellar feedback and supernovae. When a single massive star explodes as a supernova, the ejecta will interact with the ambient medium to form a supernova remnant (SNR). Since massive stars usually form and evolve in groups, their collective mechanical output into the surrounding ISM creates so-called `superbubbles'. Our group works on X-ray observations of SNRs and superbubbles with the XMM-Newton and Chandra observatories, and Dr. Kavanagh is involved in the Stellar Feedback working group of the Line Emission Mapper concept Probe mission.
SN1987A in the Large Magellanic Cloud (LMC) is the closest observed supernova explosion observed since Kepler's SN1604, making it a unique target to study supernova physics. The group works on observations of SN1987A with the James Webb Space Telescope (JWST) which are providing crucial insights into the evolution of this young supernova, including the nature of the progenitor and the origin of the iconic three-ring system, the fate of dust in the progenitor wind and supernova, and the presence of a compact object.
- Protostars and extragalactic star formation. The protostellar phase of star formation is a crucial period in the evolution of a young star and has direct implications on the likelihood of planet formation in the disk. The group works on IR observations of this phase and Dr. Kavanagh is a member of the JWST Observations of Young Protostars (JOYs) programme to investigate the physical and chemical properties of protostars and their environment.
Observations of galaxies across cosmic time have shown that the star-formation rate peaked at a redshift of ~1.5, well before galaxies with the metal content of the Milky Way existed. However, observational studies have predominantly been on young stellar objects (YSOs) in solar metallicity Milky Way star-forming regions. It is essential to investigate/understand differences in the star-formation process for planet harbouring stars such as our Sun at lower metallicities when the Universe was most actively forming stars. The group works on observations of star forming regions in the low metallicity Magellanic Clouds with the JWST.
- Calibration and data analysis software for JWST . Dr. Kavanagh worked on calibration and software development for the Mid-Infrared Instrument (MIRI) on JWST. As part of the MIRI team he worked on the development of MIRI, the JWST calibration pipeline, and the post-launch commissioning of MIRI at the JWST Mission Operations Centre at the Space Telescope Science Institute. With his group he continues to support and develop tools for the calibration and analysis of JWST data.
The Microwave Kinetic Inductance Detector (MKID) research group is developing novel superconducting detector arrays for applications in astronomy and cosmology. The current project is funded under Science Foundation Ireland’s Frontier for the Future programme (Grant number - 21/FFP-P/10213). The detector technology relies upon the kinetic inductance principle, and employs frequency-division multiplexing (FDM) for their readout. The extremely small superconducting bandgap in certain materials allows for inherent energy resolution in each pixel of an array of MKIDs at UV/optical/near-IR wavelengths, which opens the door to many interesting astronomical science targets. In more detail, our current work lies in the following areas:
- Materials Science. High quality MKID devices require materials with a high kinetic inductance fraction, while arrays with large pixel-number require good homogeneity across the sample. We are currently focussing on TiN/Ti/TiN tri-layers, by investigating the parameter space of layer thickness. Our samples are fabricated at Tyndall National Institute.
- Cryogenic Measurement and Test. Maynooth collaborate with the Dublin Institute for Advanced Studies’ MKID laboratory. Using DIAS’ state-of-the-art sub-Kelvin cryogenic infrastructure, we can cool our MKID samples to as low as 20 mK – we typically operate at 100 mK. Currently we are characterising the critical temperature (Tc), sample homogeneity, and kinetic inductance fraction of various tri-layer recipes. We are also characterising prototype MKID pixels and small arrays. Once an optimal recipe is found, we will scale up the pixel number to a few kilopixels for characterisation, with longer term plans to commission a full science instrument.
- Readout Electronics. A unique feature of MKID arrays is their inherent suitability for frequency-division multiplexing (FDM) readout. This arises by designing each pixel as a thin-film LC resonator with unique resonant frequency. This FDM approach allows thousands of pixels to be readout/monitored simultaneously with just a single feedline. This extremely fast readout, coupled with the inherent energy resolution of each pixel, opens-up very interesting astronomy/cosmology science targets.
The Star and Planet Formation group is led by Dr. Emma Whelan, an observational astrophysicist focussed on high angular resolution optical and near infrared observations. She has particular knowledge of the technique of spectro-astrometry. The question of “How do the stars and planets form?” is one of the oldest questions in the field of astrophysics and yet it remains one of the main topics driving current research. This is evidenced by the on-going large-scale investment in projects which cite an understanding of star formation and related activity as one of their main scientific goals. For example, the “Birth of Stars and Protoplanetary Systems” is one of the four themes on which the James Webb Space Telescope, will focus.
The accretion and outflow phases are important stages in the formation of a star and the accretion disks in which planets may eventually form are also widely studied. However, not all the mass in a star forming region will go into making stars. Typically 5 % will form the sub-stellar brown dwarfs. Brown dwarfs are the so-called “failed stars”, that never manage to reach masses, and therefore temperatures, high enough for hydrogen fusion to occur. The BD mass range lies just below the normal hydrogen burning mass limit and as such, brown dwarfs are the link between stars and planets. The question of how brown dwarfs form is still an open one in the field of star formation and an important step towards understanding this came when it was found that brown dwarfs were strong accretors, had accretion disks and could drive outflows.
The expertise of Dr. Emma Whelan’s group is in high angular resolution spectroscopic observations of outflow and accretion activity in young stars and brown dwarfs. The group is particularly interested in the question of how angular momentum is removed from a young star and how the jets and winds launched from young stars impact future planet formation. Related to this is the question of how early in the lifetime of a star planet formation begins. The group also investigates how outflow and accretion activity compares in brown dwarfs and young stars. They are involved in several projects on these topics. Dr. Whelan mainly works with the instruments of the European Southern Observatory’s Very Large Telescope and most recently the JWST. She also has experience in the radio and X-ray regimes and is very much focussed on the arrival of the European Southern Observatory’s Extremely Large Telescope.
Our research seeks to understand the properties of matter at extremely high temperatures and densities, such as could be found in the first millisecond of the Big Bang, in supernova explosions, and in neutron stars and neutron star mergers. At these temperatures and densities, quarks and gluons rather than hadrons (protons, neutrons, pions etc) are the relevant degrees of freedom.
Through computer simulations of the theory of strong interactions (quantum chromodynamics) we study the thermodynamic and transport properties of matter and the properties of whatever particles exist in these conditions, and aim to relate these to what can be observed for example in the structure of neutron stars and their cooling.
Research on the cosmic microwave background (CMB) is led by Dr Créidhe O’Sullivan and Dr Neil Trappe. The CMB is relic radiation from the Big Bang and contains very faint temperature and polarization features, or anisotropies, imprinted on it in the early Universe. The European Space Agency’s Planck satellite, a space mission dedicated to the study of CMB anisotropies, measured the temperature anisotropies to fundamental limits. These anisotropies were caused by structures forming in the early Universe and so provided some of our most important constraints on models of cosmology and fundamental physics. The standard model of cosmology, the ΛCDM model, with just 6 cosmological parameters, continues to give an excellent fit to CMB data and has passed all tests since it was developed more than three decades ago. Planck has placed stringent constraints on our models of the early Universe and its large-scale structure and yet questions remain, in particular how fluctuations in the early Universe were first generated. The theory of Inflation, considered an extension to the Big Bang theory, provides a mechanism for generating small departures from uniformity that can seed formation of subsequent structures. According to Inflation, the Universe underwent a brief period of exponential expansion 10-36 seconds after the Big Bang. The basic inflationary paradigm is accepted by most physicists because of its ability to solve fine-tuning problems of big bang cosmology as well as explain the origin of large-scale structure. Despite these successes however, we have as yet no proof for inflation. If Inflation is correct, then gravitational waves produced in the very early Universe will imprint a very faint polarization pattern on the CMB, known as the primordial B-modes. The next ambitious goal for CMB astronomy is to detect and map this polarization signature.
As well as the CMB anisotropies, the absolute CMB frequency spectrum is a second key observable to challenge the accepted standard cosmological model. Departures from a blackbody spectrum, i.e., spectral distortions, encode information about the thermal history of the Universe from the early stages (with primordial distortions due to inflation and cosmological recombination lines) up until today.
Current projects include:
The Q & U Bolometric Interferometer for Cosmology (QUBIC) is a novel ground-based telescope that is designed to measure very faint B-mode polarisation fluctuations, a goal that demands exquisite sensitivity and control of instrumental systematic errors since the signal is expected to be extremely small, of the order of a few tens of nK. QUBIC exploits a very promising technique to do this – bolometric interferometry combined with spectral imaging.
BISOU (Balloon Interferometer for Spectral Observations of the Universe) is a study of the viability of a balloon-borne spectrometer, a pathfinder for a future space mission dedicated to the measurements of the CMB spectral distortions, while consolidating the instrumental concept and improving the readiness of some of its key sub-systems. The BISOU concept is based on a Fourier Transform Spectrometer (FTS), covering a spectral range from about 90 GHz to 2 THz, adapted from previous mission proposals such as PIXIE and FOSSIL.