I'm Mike Jones, a Juan de la Cierva post-doctoral fellow at the Instituto de Astrofísica de Andalucía working with Lourdes Verdes-Montenegro on the AMIGA project. My research is in extragalactic astronomy, focusing mostly on galaxy surveys in the local Universe, in particular on the neutral gas content of galaxies as a function of their surrounding environments. I graduated with a PhD in Astronomy from Cornell University in 2016 after 5 years working with Martha Haynes and Riccardo Giovanelli on the ALFALFA survey. I gained my undergraduate degree in Natural Sciences (Astrophysics) from the University of Cambridge in 2011. I'm very active and regularly play football (soccer), cycle, hike and occasionally rock climb. I am also fond of photography, including astrophotography.
AMIGA:The AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies) focuses on a population of carefully selected isolated galaxies and has collected a rich multi-wavelength dataset to characterise their properties. This sample defines a benchmark for galaxies that reside in an almost nurture-free environment and thus acts as a control sample for studies of the impact on interactions on galaxy properties, whether it be star formation rates, gas content, AGN activity, or numerous others. In addition, these galaxies form an ideal laboratory for investigating secular evolution in galaxies, as the influence of neighbours is minimised.
In Jones et al. 2018a I used the global HI profiles of several hundred isolated galaxies, observed by the AMIGA team or gathered from the literature, to define a new standard for the HI content of galaxies in the absence of interactions. The resulting optical to HI scaling relations had not been updated for the most isolated galaxies since Haynes & Giovanelli 1984, with most of the other recent scaling relation being measured with sources from HI surveys, which are intrinsically biased towards gas-rich galaxies. The increased sample size, morphological diversity, and improved maximum likelihood fitting method also gave more self-consistent relations than found previously.
ALFALFA: During my PhD I worked with Professors Martha Haynes and Riccardo Giovanelli on the ALFALFA HI survey, a blind 21 cm survey out to a maximum redshift of 0.06 and covering 7,000 square degrees of the sky. ALFALFA represents the cutting edge of large area, blind HI surveys. It used the Arecibo radio telescope in Puerto Rico, the largest single dish telescope in the world at the time, and a 7 pixel feed array (ALFA). The final HI source catalogue contains over 30,000 extragalactic source and can be found here.
My research focused on the global properties of the survey, investigating the statistical trends and biases present in the dataset. This included a quantification of the impact of source confusion on current and future HI surveys (Jones et al. 2015) and the construction of a generic model for the contribution of confusion noise to deep HI stacking experiments (Jones et al. 2016a). I also investigated the role environment plays in influencing the shape of the HI mass function of galaxies (HIMF), finding that the ‘knee’ mass increases towards denser regions, but not finding any evidence of a change in the low-mass slope (Jones et al. 2016b).
My work on ALFALFA, and in particular the HIMF, has continued as a post-doc. In Jones et al. 2018b I calculated the HIMF for the final ALFALFA sample (Haynes et al. 2018). This is the most precise measurement of the HIMF to date. However, while the ‘knee’ is determined over a cosmologically fair volume and varies little across the survey footprint, the low-mass slope is only measurable in the relatively nearby Universe (D < 60 Mpc) with ALFALFA. Hence we see large shifts in the gradient of the low-mass slope in different regions of the sky. There is tentative evidence that the low-mass slope steepens within the large scale overdensity surrounding the Virgo cluster, perhaps due to the presence of gas-rich inflowing filaments, and flattens in the void in the foreground of the Pisces-Perseus supercluster. However, more investigation is required.
Ultra-diffuse galaxies: Ultra-diffuse galaxies, or UDGs, are a class of recently identified extremely low surface brightness (LSB) galaxies which have been principally found in galaxy clusters. While astronomers have been studying LSB galaxies for decades, including some which are now classified as UDGs, the striking results of van Dokkum et al. 2015 and Koda et al. 2015 was just how prevalent they are, even at the lowest surface brightnesses and in the dense cluster environments. There are many open questions about the formation and survival of these galaxies and their connection to the other LSB galaxies and normal galaxies.
While the vast majority of UDGs are red, spheroidal objects located in or around groups and clusters, Leisman et al. 2017 identified a sample of isolated, blue, HI-bearing UDGs (HUDs) that were strongly detected as HI sources in ALFALFA, but have almost invisible optical counterparts in the Sloan Digital Sky Survey. In Jones et al. 2018c we measured the cosmic number density of these source by comparison with the global ALFALFA population, and found that although many fewer HUDs than red UDGs have been found to date, their overall abundances are likely quite similar. However, the connection between HUDs and red UDGs remains uncertain; they may be two phases of one population or two completely separate populations. Further investigation of the stellar properties of HUDs is on-going with the aim of directly addressing this open question.
APPSS: I am the co-PI (along with Rebecca Koopmann) of the Arecibo Pisces-Perseus Supercluster Survey (APPSS). This is an ALFALFA follow-up program to observe dwarf galaxies, below the ALFALFA sensitivity limit, in order to increase the source density of galaxies with known redshifts and velocity widths in the vicinity of PPS. With this dataset we aim to measure with high signal-to-noise the the radial inflow of galaxies onto the supercluster filament through the use of the baryonic Tully-Fisher relation. The majority of the work for this project is being conducted by the student and faculty members of the Undergraduate ALFALFA Team (UAT, organised by Martha Haynes and Rebecca Koopmann), a network of undergraduate-focused institutions across the USA that contribute and gain research experience within the wider ALFALFA project.
Teaching: I was a teaching assistant for Cornell's Astro1101 and Astro1102 courses for two years. I led two weekly sections, typically with around 20-30 students, as well as performing a guest lecture to the full class (around 200 students). I have written and graded both homeworks and exams for these courses. Additionally, another graduate student (Michael Lam) and I took on a volunteer project to bring the lab component of these courses up to date. I have also given guest lectures for Cornell's first-year writing seminars in astronomy.
Undergraduate Workshops: I've co-written and led workshops as part of Cornell Astronomy's REU program: A Brief Introduction to Python, and Exploring Early Galaxies with the CCAT (an introduction to blind galaxy surveys). I have also demonstrated observing, lectured and mentored students at the Undergraduate ALFALFA Team workshop at Arecibo, and undergraduate researchers in the ALFALFA team at Cornell.
Department contributions: While a PhD student I was both the treasurer and vice president of the Cornell astronomy graduate student society. As a post-doc in Granada I started and coordinated a journal club for the students and post-docs at the IAA.
Outreach: While in Spain my public outreach options have been limited, but as a PhD student I was involved in a number of local and online outreach events/programs, including: Focus for Teens, Museum in the Dark, Ask an Astronomer, Ask an Astronomer - Podcast, and Ask an Astronomer - Reddit AMA.
Ask an Astronomer: Cornell astronomy department's public service for anyone curious about astronomy, planetary science, astrophysics or cosmology. So if you have any burning questions please visit our website.
Physics at Exeter guest lecture: I appeared as a guest on the University of Exeter "Physics at Exeter" YouTube channel.