Publications by Chris Lintott

SDSS-IV MaNGA: the different quenching histories of fast and slow rotatorsSDSS-IV MaNGA: the different quenching histories of fast and slow rotators


RJ Smethurst, KL Masters, CJ Lintott, A Weijmans, M Merrifield, SJ Penny, A Aragon-Salamanca, J Brownstein, K Bundy, N Drory, DR Law, RC Nichol

The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists


JL Christiansen, IJM Crossfield, G Barentsen, CJ Lintott, T Barclay, BD Simmons, E Petigura, JE Schlieder, CD Dressing, A Vanderburg, C Allen, A McMaster, G Miller, M Veldthuis, S Allen, Z Wolfenbarger, B Cox, J Zemiro, AW Howard, J Livingston, E Sinukoff, T Catron, A Grey, JJE Kusch, I Terentev, M Vales, MH Kristiansen

The First Post-Kepler Brightness Dips of KIC 8462852


TS Boyajian, R Alonso, A Ammerman, D Armstrong, AA Ramos, K Barkaoui, TG Beatty, Z Benkhaldoun, P Benni, RO Bentley, A Berdyugin, S Berdyugina, S Bergeron, A Bieryla, MG Blain, AC Blanco, EHL Bodman, A Boucher, M Bradley, SM Brincat, TG Brink, J Briol, DJA Brown, J Budaj, A Burdanov, B Cale, MA Carbo, RC Garcia, WJ Clark, GC Clayton, JL Clem, PH Coker, EM Cook, CM Copperwheat, JL Curtis, RM Cutri, B Cseh, CH Cynamon, AJ Daniels, JRA Davenport, HJ Deeg, R De Lorenzo, T De Jaeger, J-B Desrosiers, J Dolan, DJ Dowhos, F Dubois, R Durkee, S Dvorak, L Easley, N Edwards, TG Ellis, E Erdelyi, S Ertel, RG Farfan, J Farihi, AV Filippenko, E Foxell, D Gandolfi, F Garcia, F Giddens, M Gillon, J-L Gonzalez-Carballo, C Gonzalez-Fernandez, JIG Hernandez, KA Graham, KA Greene, J Gregorio, N Hallakoun, O Hanyecz, GR Harp, GW Henry, E Herrero, CF Hildbold, D Hinzel, G Holgado, B Ignacz, I Ilyin, VD Ivanov, E Jehin, HE Jermak, S Johnston, S Kafka, C Kalup, E Kardasis, S Kaspi, GM Kennedy, F Kiefer, CL Kielty, D Kessler, H Kiiskinen, TL Killestein, RA King, V Kollar, H Korhonen, C Kotnik, R Konyves-Toth, L Kriskovics, N Krumm, V Krushinsky, E Kundra, F-R Lachapelle, D LaCourse, P Lake, K Lam, GP Lamb, D Lane, MW Lau, P Lewin, C Lintott, C Lisse, L Logie, N Longeard, ML Villanueva, EW Ludington, A Mainzer, L Malo, C Maloney, A Mann, A Mantero, M Marengo, J Marchant, MJM Gonzalez, JR Masiero, JC Mauerhan, J McCormac, A McNeely, HYA Meng, M Miller, LA Molnar, JC Morales, BM Morris, MW Muterspaugh, D Nespral, CR Nugent, KM Nugent, A Odasso, D O'Keeffe, A Oksanen, JM O'Meara, A Ordasi, H Osborn, JJ Ott, JR Parks, DR Perez, V Petriew, R Pickard, A Pal, P Plavchan, D Pollacco, FP Nunez, FJ Pozuelos, S Rau, S Redfield, H Relles, I Ribas, J Richards, JLO Saario, EJ Safron, JM Sallai, K Sarneczky, BE Schaefer, CF Schumer, M Schwartzendruber, MH Siegel, APV Siemion, BD Simmons, JD Simon, S Simon-Diaz, ML Sitko, H Socas-Navarro, A Sodor, D Starkey, IA Steele, G Stone, KG Strassmeier, RA Street, T Sullivan, J Suomela, JJ Swift, GM Szabo, R Szabo, R Szakats, T Szalai, AM Tanner, B Toledo-Padron, T Tordai, AHMJ Triaud, JD Turner, JH Ulowetz, M Urbanik, S Vanaverbeke, A Vanderburg, K Vida, BP Vietje, J Vinko, K Von Braun, EO Waagen, D Walsh, CA Watson, RC Weir, K Wenzel, CW Plaza, MW Williamson, JT Wright, MC Wyatt, W Zheng, G Zsidi

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies


AD Kapinska, I Terentev, OI Wong, SS Shabala, H Andernach, L Rudnick, L Storer, JK Banfield, KW Willett, F de Gasperin, CJ Lintott, AR Lopez-Sanchez, E Middelberg, RP Norris, K Schawinski, N Seymour, B Simmons

Galaxy Zoo: the interplay of quenching mechanisms in the group environment

Monthly Notices of the Royal Astronomical Society Oxford University Press 469 (2017) 3670-3687

RJ Smethurst, C Lintott, SP Bamford, RE Hart, SJ Kruk, KL Masters, RC Nichol, BD Simmons

Does the environment of a galaxy directly influence the quenching history of a galaxy? Here we investigate the detailed morphological structures and star formation histories of a sample of SDSS group galaxies with both classifications from Galaxy Zoo 2 and NUV detections in GALEX. We use the optical and NUV colours to infer the quenching time and rate describing a simple exponentially declining SFH for each galaxy, along with a control sample of field galaxies. We find that the time since quenching and the rate of quenching do not correlate with the relative velocity of a satellite but are correlated with the group potential. This quenching occurs within an average quenching timescale of ∼2.5 Gyr from star forming to complete quiescence, during an average infall time (from ∼10R200 to 0.01R200) of ∼2.6 Gyr. Our results suggest that the environment does play a direct role in galaxy quenching through quenching mechanisms which are correlated with the group potential, such as harassment, interactions or starvation. Environmental quenching mechanisms which are correlated with satellite velocity, such as ram pressure stripping, are not the main cause of quenching in the group environment. We find that no single mechanism dominates over another, except in the most extreme environments or masses. Instead an interplay of mergers, mass & morphological quenching and environment driven quenching mechanisms dependent on the group potential drive galaxy evolution in groups.

Galaxy Zoo: Finding offset discs and bars in SDSS galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 469 (2017) 3363-3373

SI Kruk, CJ Lintott, BD Simmons, SP Bamford, CN Cardamone, L Fortson, RE Hart, B Häußler, KL Masters, RC Nichol, K Schawinski, RJ Smethurst

We use multi-wavelength SDSS images and Galaxy Zoo morphologies to identify a sample of $\sim$$270$ late-type galaxies with an off-centre bar. We measure offsets in the range 0.2-2.5 kpc between the photometric centres of the stellar disc and stellar bar. The measured offsets correlate with global asymmetries of the galaxies, with those with largest offsets showing higher lopsidedness. These findings are in good agreement with predictions from simulations of dwarf-dwarf tidal interactions producing off-centre bars. We find that the majority of galaxies with off-centre bars are of Magellanic type, with a median mass of $10^{9.6} M_{\odot}$, and 91% of them having $M_{\star}<3\times10^{10} M_{\odot}$, the characteristic mass at which galaxies start having higher central concentrations attributed to the presence of bulges. We conduct a search for companions to test the hypothesis of tidal interactions, but find that a similar fraction of galaxies with offset bars have companions within 100 kpc as galaxies with centred bars. Although this may be due to the incompleteness of the SDSS spectroscopic survey at the faint end, alternative scenarios that give rise to offset bars such as interactions with dark companions or the effect of lopsided halo potentials should be considered. Future observations are needed to confirm possible low mass companion candidates and to determine the shape of the dark matter halo, in order to find the explanation for the off-centre bars in these galaxies.

A transient search using combined human and machine classifications


DE Wright, CJ Lintott, SJ Smartt, KW Smith, L Fortson, L Trouille, CR Allen, M Beck, MC Bouslog, A Boyer, KC Chambers, H Flewelling, W Granger, EA Magnier, A McMaster, GRM Miller, JE O'Donnell, B Simmons, H Spiers, JL Tonry, M Veldthuis, RJ Wainscoat, C Waters, M Willman, Z Wolfenbarger, DR Young

Galaxy Zoo: star-formation versus spiral arm number

Monthly Notices of the Royal Astronomical Society Oxford University Press 468 (2017) 1850-1863

RE Hart, SP Bamford, KRV Casteels, SJ Kruk, C Lintott, KL Masters

Spiral arms are common features in low-redshift disc galaxies, and are prominent sites of star-formation and dust obscuration. However, spiral structure can take many forms: from galaxies displaying two strong `grand design' arms, to those with many `flocculent' arms. We investigate how these different arm types are related to a galaxy's star-formation and gas properties by making use of visual spiral arm number measurements from Galaxy Zoo 2. We combine UV and mid-IR photometry from GALEX and WISE to measure the rates and relative fractions of obscured and unobscured star formation in a sample of low-redshift SDSS spirals. Total star formation rate has little dependence on spiral arm multiplicity, but two-armed spirals convert their gas to stars more efficiently. We find significant differences in the fraction of obscured star-formation: an additional $\sim 10$ per cent of star-formation in two-armed galaxies is identified via mid-IR dust emission, compared to that in many-armed galaxies. The latter are also significantly offset below the IRX-$\beta$ relation for low-redshift star-forming galaxies. We present several explanations for these differences versus arm number: variations in the spatial distribution, sizes or clearing timescales of star-forming regions (i.e., molecular clouds), or contrasting recent star-formation histories.

Supermassive black holes in disk-dominated galaxies outgrow their bulges and co-evolve with their host galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 470 (2017) 1559-1569

BD Simmons, RJ Smethurst, C Lintott

The deep connection between galaxies and their supermassive black holes is central to modern astrophysics and cosmology. The observed correlation between galaxy and black hole mass is usually attributed to the contribution of major mergers to both. We make use of a sample of galaxies whose disk-dominated morphologies indicate a major-merger-free history and show that such systems are capable of growing supermassive black holes at rates similar to quasars. Comparing black hole masses to conservative upper limits on bulge masses, we show that the black holes in the sample are typically larger than expected if processes creating bulges are also the primary driver of black hole growth. The same relation between black hole and total stellar mass of the galaxy is found for the merger-free sample as for a sample which has experienced substantial mergers, indicating that major mergers do not play a significant role in controlling the coevolution of galaxies and black holes. We suggest that more fundamental processes which contribute to galaxy assembly are also responsible for black hole growth.

Fading AGN Candidates: AGN Histories and Outflow Signatures

Astrophysical Journal 835 (2017)

WC Keel, CJ Lintott, WP Maksym, VN Bennert, SD Chojnowski, A Moiseev, A Smirnova, K Schawinski, LF Sartori, CM Urry, A Pancoast, M Schirmer, B Scott, C Showley, K Flatland

� 2017. The American Astronomical Society. All rights reserved. We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q ion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar-Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2 � 10 4 yr before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission, morphologically suggestive of outflow, are common, their kinematic structure shows some to be in regular rotation. UGC 7342 exhibits local signatures of outflows < 300 km s -1 , largely associated with very diffuse emission, and possibly entraining gas in one of the clouds seen in Hubble Space Telescope images. Only in the Teacup AGN do we see outflow signatures of the order of 1000 km s -1 . In contrast to the extended emission regions around many radio-loud AGNs, the clouds around these fading AGNs consist largely of tidal debris being externally illuminated but not displaced by AGN outflows.

Galaxy Zoo and SpArcFiRe: Constraints on spiral arm formation mechanisms from spiral arm number and pitch angles

Monthly Notices of the Royal Astronomical Society Oxford University Press 472 (2017) 2263–2279-

RE Hart, SP Bamford, WB Hayes, CN Cardamone, WC Keel, SJ Kruk, C Lintott, KL Masters, BD Simmons, RJ Smethurst

In this paper we study the morphological properties of spiral galaxies, including measurements of spiral arm number and pitch angle. Using Galaxy Zoo 2, a stellar mass-complete sample of 6,222 SDSS spiral galaxies is selected. We use the machine vision algorithm SpArcFiRe to identify spiral arm features and measure their associated geometries. A support vector machine classifier is employed to identify reliable spiral features, with which we are able to estimate pitch angles for half of our sample. We use these machine measurements to calibrate visual estimates of arm tightness, and hence estimate pitch angles for our entire sample. The properties of spiral arms are compared with respect to various galaxy properties. The star formation properties of galaxies vary significantly with arm number, but not pitch angle. We find that galaxies hosting strong bars have spiral arms substantially (4-6) looser than unbarred galaxies. Accounting for this, spiral arms associated with many-arm structures are looser (by 2) than those in two-arm galaxies. In contrast to this average trend, galaxies with greater bulge-to-total stellar mass ratios display both fewer and looser spiral arms. This effect is primarily driven by the galaxy disc, such that galaxies with more massive discs contain more spiral arms with tighter pitch angles. This implies that galaxy central mass concentration is not the dominant cause of pitch angle and arm number variations between galaxies, which in turn suggests that not all spiral arms are governed by classical density waves or modal theories.

Gravity Spy: integrating advanced LIGO detector characterization, machine learning, and citizen science.

Classical and quantum gravity 34 (2017)

M Zevin, S Coughlin, S Bahaadini, E Besler, N Rohani, S Allen, M Cabero, K Crowston, AK Katsaggelos, SL Larson, TK Lee, C Lintott, TB Littenberg, A Lundgren, C Østerlund, JR Smith, L Trouille, V Kalogera

With the first direct detection of gravitational waves, the advanced laser interferometer gravitational-wave observatory (LIGO) has initiated a new field of astronomy by providing an alternative means of sensing the universe. The extreme sensitivity required to make such detections is achieved through exquisite isolation of all sensitive components of LIGO from non-gravitational-wave disturbances. Nonetheless, LIGO is still susceptible to a variety of instrumental and environmental sources of noise that contaminate the data. Of particular concern are noise features known as glitches, which are transient and non-Gaussian in their nature, and occur at a high enough rate so that accidental coincidence between the two LIGO detectors is non-negligible. Glitches come in a wide range of time-frequency-amplitude morphologies, with new morphologies appearing as the detector evolves. Since they can obscure or mimic true gravitational-wave signals, a robust characterization of glitches is paramount in the effort to achieve the gravitational-wave detection rates that are predicted by the design sensitivity of LIGO. This proves a daunting task for members of the LIGO Scientific Collaboration alone due to the sheer amount of data. In this paper we describe an innovative project that combines crowdsourcing with machine learning to aid in the challenging task of categorizing all of the glitches recorded by the LIGO detectors. Through the Zooniverse platform, we engage and recruit volunteers from the public to categorize images of time-frequency representations of glitches into pre-identified morphological classes and to discover new classes that appear as the detectors evolve. In addition, machine learning algorithms are used to categorize images after being trained on human-classified examples of the morphological classes. Leveraging the strengths of both classification methods, we create a combined method with the aim of improving the efficiency and accuracy of each individual classifier. The resulting classification and characterization should help LIGO scientists to identify causes of glitches and subsequently eliminate them from the data or the detector entirely, thereby improving the rate and accuracy of gravitational-wave observations. We demonstrate these methods using a small subset of data from LIGO's first observing run.

Galaxy Zoo: Quantitative Visual Morphological Classifications for 48,000 galaxies from CANDELS

Monthly Notices of the Royal Astronomical Society Oxford University Press 464 (2016) 4420-4447

AM Koekemoer, A Mortlock, JA Newman, BD Simmons, C Krawczyk, SJ Kruk, DH McIntosh, RJ Smethurst, RC Nichol, HC Ferguson, KW Willett, KL Masters, JS Kartaltepe, B Häußler, S Kaviraj, L Fortson, ADJ Ownsworth, SM Faber, SL Finkelstein, A Fontana, A Galametz, R Grützbauch, D Koo, J Lotz, M Salvato

We present quantified visual morphologies of approximately 48 000 galaxies observed in three Hubble Space Telescope legacy fields by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and classified by participants in the Galaxy Zoo project. 90 per cent of galaxies have z ≤ 3 and are observed in rest-frame optical wavelengths by CANDELS. Each galaxy received an average of 40 independent classifications, which we combine into detailed morphological information on galaxy features such as clumpiness, bar instabilities, spiral structure, and merger and tidal signatures. We apply a consensus-based classifier weighting method that preserves classifier independence while effectively down-weighting significantly outlying classifications. After analysing the effect of varying image depth on reported classifications, we also provide depth-corrected classifications which both preserve the information in the deepest observations and also enable the use of classifications at comparable depths across the full survey. Comparing the Galaxy Zoo classifications to previous classifications of the same galaxies shows very good agreement; for some applications, the high number of independent classifications provided by Galaxy Zoo provides an advantage in selecting galaxies with a particular morphological profile, while in others the combination of Galaxy Zoo with other classifications is a more promising approach than using any one method alone. We combine the Galaxy Zoo classifications of ‘smooth’ galaxies with parametric morphologies to select a sample of featureless discs at 1 ≤ z ≤ 3, which may represent a dynamically warmer progenitor population to the settled disc galaxies seen at later epochs.

Galaxy Zoo: Major Galaxy Mergers Are Not a Significant Quenching Pathway


AK Weigel, K Schawinski, N Caplar, A Carpineti, RE Hart, S Kaviraj, WC Keel, SJ Kruk, CJ Lintott, RC Nichol, BD Simmons, RJ Smethurst

Transforming Libraries and Archives through Crowdsourcing

D-Lib Magazine 23 (2017)

V Van Hyning, S Blickhan, L Trouille, C Lintott

This article will showcase the aims and research goals of the project entitled "Transforming Libraries and Archives through Crowdsourcing", recipient of a 2016 Institute for Museum and Library Services grant. This grant will be used to fund the creation of four bespoke text and audio transcription projects which will be hosted on the Zooniverse, the world-leading research crowdsourcing platform. These transcription projects, while supporting the research of four separate institutions, will also function as a means to expand and enhance the Zooniverse platform to better support galleries, libraries, archives and museums (GLAM institutions) in unlocking their data and engaging the public through crowdsourcing.

SDSS IV MaNGA: Discovery of an Ha Blob Associated with a Dry Galaxy Pair-Ejected Gas or a "Dark" Galaxy Candidate?


L Lin, J-H Lin, C-H Hsu, H Fu, S Huang, SF Sanchez, S Gwyn, JD Gelfand, E Cheung, K Masters, S Peirani, W Rujopakarn, DV Stark, F Belfiore, MS Bothwell, K Bundy, A Hagen, L Hao, S Huang, D Law, C Li, C Lintott, R Maiolino, A Roman-Lopes, W-H Wang, T Xiao, F Yuan, D Bizyaev, E Malanushenko, N Drory, JG Fernandez-Trincado, Z Pace, K Pan, D Thomas

Galaxy Zoo: comparing the demographics of spiral arm number and a new method for correcting redshift bias


RE Hart, SP Bamford, KW Willett, KL Masters, C Cardamone, CJ Lintott, RJ Mackay, RC Nichol, CK Rosslowe, BD Simmons, RJ Smethurst

The milky way project and atlasgal: The distribution and physical properties of cold clumps near infrared bubbles

Astrophysical Journal 825 (2016)

S Kendrew, H Beuther, R Simpson, T Csengeri, M Wienen, CJ Lintott, MS Povich, C Beaumont, F Schuller

© 2016. The American Astronomical Society. All rights reserved. We present a statistical study of the distribution and physical properties of cold, dense material in and around the inner Galactic Plane near-infrared bubbles as cataloged by the Milky Way Project citizen scientists. Using data from the Atacama Pathfinder Experiment (APEX) Telescope Large Area Survey of the Galaxy 870 μm survey, we show that 48 ± 2% of all cold clumps in the studied survey region (|l| ≤ 65°, |b| ≤ 1°) are found in close proximity to a bubble, and 25 ± 2% appear directly projected toward a bubble rim. A two-point correlation analysis confirms the strong correlation of massive cold clumps with expanding bubbles. It shows an overdensity of clumps along bubble rims that grows with increasing bubble size, which shows how interstellar medium material is reordered on large scales by bubble expansion around regions of massive star formation. The highest column density clumps appear to be resistent to the expansion, remaining overdense toward the bubbles' interior rather than being swept up by the expanding edge. Spectroscopic observations in ammonia show that cold dust clumps near bubbles appear to be denser, hotter, and more turbulent than those in the field, offering circumstantial evidence that bubble-associated clumps are more likely to be forming stars. These observed differences in physical conditions persist beyond the region of the bubble rims.

Galaxy Zoo: Evidence for rapid, recent quenching within a population of AGN host galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 463 (2016) 2986-2996

RJ Smethurst, C Lintott, BD Simmons, K Schawinski, SP Bamford, CN Cardamone, SI Kruk, KL Masters, CM Urry, KW Willett, OI Wong

We present a population study of the star formation history of 1244 Type 2 AGN host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualise the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.



MJ Kuchner, SM Silverberg, AS Bans, S Bhattacharjee, SJ Kenyon, JH Debes, T Currie, L Garcia, D Jung, C Lintott, M McElwain, DL Padgett, LM Rebull, JP Wisniewski, E Nesvold, K Schawinski, ML Thaller, CA Grady, J Biggs, M Bosch, T Cernohous, HAD Luca, M Hyogo, LLW Wah, A Piipuu, F Pineiro, DD Collaboration