Publications by Michele Cappellari


The fifteenth data release of the Sloan Digital Sky Surveys: First release of MaNGA-derived quantities, data visualization tools, and Stellar Library

Astrophysical Journal Supplement Institute of Physics 240 (2019)

DS Aguado, R Ahumada, A Almeida, M Cappellari, R Davies, C Lintott

Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.


Improved dynamical constraints on the masses of the central black holes in nearby low-mass early-type galactic nuclei and the first black hole determination for NGC 205

Astrophysical Journal American Astronomical Society 872 (2019) 104

DD Nguyen, AC Seth, N Neumayer, M Cappellari, E al.

We improve the dynamical black hole (BH) mass estimates in three nearby low-mass early-type galaxies: NGC 205, NGC 5102, and NGC 5206. We use new Hubble Space Telescope (HST)/STIS spectroscopy to fit the star formation histories of the nuclei in these galaxies, and use these measurements to create local color–mass-to-light ratio (M/L) relations. We then create new mass models from HST imaging and combined with adaptive optics kinematics, we use Jeans dynamical models to constrain their BH masses. The masses of the central BHs in NGC 5102 and NGC 5206 are both below one million solar masses and are consistent with our previous estimates, ${9.12}_{-1.53}^{+1.84}\times {10}^{5}$ M ⊙ and ${6.31}_{-2.74}^{+1.06}\times {10}^{5}$ M ⊙ (3σ errors), respectively. However, for NGC 205, the improved models suggest the presence of a BH for the first time, with a best-fit mass of ${6.8}_{-6.7}^{+95.6}\times {10}^{3}$ M ⊙ (3σ errors). This is the least massive central BH mass in a galaxy detected using any method. We discuss the possible systematic errors of this measurement in detail. Using this BH mass, the existing upper limits of both X-ray, and radio emissions in the nucleus of NGC 205 suggest an accretion rate lesssim10−5 of the Eddington rate. We also discuss the color–M/L eff relations in our nuclei and find that the slopes of these vary significantly between nuclei. Nuclei with significant young stellar populations have steeper color–M/L eff relations than some previously published galaxy color–M/L eff relations.


Recovering stellar population parameters via different population models and stellar libraries

Monthly Notices of the Royal Astronomical Society Oxford University Press 485 (2019) 1675-1693

J Ge, S Mao, Y Lu, M Cappellari, R Yan

Three basic ingredients are required to generate a simple stellar population (SSP) library, i.e. an initial mass function (IMF), a stellar evolution model/isochrones, and an empirical/theoretical stellar spectral library. However, there are still some uncertainties to the determination and understanding of these ingredients. We perform the spectral fitting to test the relative parameter offsets between these uncertainties using two different stellar population models, two different empirical stellar libraries, two different isochrones, and the Salpeter and Chabrier IMFs. Based on these setups, we select five SSP libraries generated with the Galaxev/STELIB and Vazdekis/MILES models, and apply them to the pPXF full-spectrum fitting of both MaNGA and mock spectra. We find that: (1) Compared to the Galaxev/STELIB model, spectral fitting qualities with the Vazdekis/MILES model have significant improvements for those metal-rich (especially oversolar) spectra, which cause better reduced χ 2 distributions and more precisely fitted absorption lines. This might due to the lack of metal-rich stars in the empirical STELIB library, or code improvement of the Vazdekis model. (2) When applying the Vazdekis/MILES model for spectral fitting, the IMF variation will lead to not only a systematic offset in M ∗ /L r , but also offsets in age and metallicity, and these offsets increase with increasing stellar population ages. However, the IMF variation caused metallicity offsets disappear in the case of Galaxev/STELIB based libraries. (3) The Padova2000 model provides a better match to the MaNGA galaxy spectra at [M/H] L < −1.0, while the BaSTI model match the local galaxy spectra better at [M/H] L > −1.0. Current tests suggest that spectral fitting with the Vazdekis/MILES + BaSTI combination would be a better choice for local galaxies.


WISDOM project – IV. A molecular gas dynamical measurement of the supermassive black hole mass in NGC 524

Monthly Notices of the Royal Astronomical Society Oxford University Press 485 (2019) 4359–4374-

MD Smith, M Bureau, TA Davis, M Cappellari, L Liu, EV North, K Onishi, S Iguchi, M Sarzi

We present high angular resolution (0.3 arcsec or 37 pc) Atacama Large Millimeter/submillimeter Array observations of the CO(2–1) line emission from a central disc in the early-type galaxy NGC 524. This disc is shown to be dynamically relaxed, exhibiting ordered rotation about a compact 1.3 mm continuum source, which we identify as emission from an active supermassive black hole (SMBH). There is a hole at the centre of the disc slightly larger than the SMBH sphere of influence. An azimuthal distortion of the observed velocity field is found to be due to either a position angle warp or radial gas flow over the inner 2. 5. By forward-modelling the observations, we obtain an estimate of the SMBH mass of 4.0+3.5 −2.0 × 108 M, where the uncertainties are at the 3σ level. The uncertainties are dominated by the poorly constrained inclination and the stellar mass-to-light ratio of this galaxy, and our measurement is consistent with the established correlation between SMBH mass and stellar velocity dispersion. Our result is roughly half that of the previous stellar dynamical measurement, but is consistent within the uncertainties of both. We also present and apply a new tool for modelling complex molecular gas distributions.


The data analysis pipeline for the SDSS-IV MaNGA IFU galaxy survey: Emission-line modeling

Astronomical Journal American Astronomical Society 158 (2019) 160

F Belfiore, KB Westfall, A Schaefer, M Cappellari, E al.

SDSS-IV MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is the largest integral-field unit (IFU) spectroscopy survey to date, aiming to observe a statistically representative sample of 10,000 low-redshift galaxies. In this paper, we study the reliability of the emission-line fluxes and kinematic properties derived by the MaNGA Data Analysis Pipeline (DAP). We describe the algorithmic choices made in the DAP with regards to measuring emission-line properties, and the effect of our adopted strategy of simultaneously fitting the continuum and line emission. The effects of random errors are quantified by studying various fit-quality metrics, idealized recovery simulations, and repeat observations. This analysis demonstrates that the emission lines are well fit in the vast majority of the MaNGA data set and the derived fluxes and errors are statistically robust. The systematic uncertainty on emission-line properties introduced by the choice of continuum templates is also discussed. In particular, we test the effect of using different stellar libraries and simple stellar-population models on the derived emission-line fluxes and the effect of introducing different tying prescriptions for the emission-line kinematics. We show that these effects can generate large (>0.2 dex) discrepancies at low signal-to-noise ratio and for lines with low equivalent width (EW); however, the combined effect is noticeable even for Hα EW > 6 Å. We provide suggestions for optimal use of the data provided by SDSS data release 15 and propose refinements on the DAP for future MaNGA data releases.


WISDOM project – V. Resolving molecular gas in Keplerian rotation around the supermassive black hole in NGC 0383

Monthly Notices of the Royal Astronomical Society Oxford University Press 490 (2019) 319-330

L Liu, EV North, TA Davis, M Bureau, M Cappellari, S Iguchi, K Onishi, M Sarzi, TG Williams

As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), we present a measurement of the mass of the supermassive black hole (SMBH) in the nearby early-type galaxy NGC 0383 (radio source 3C 031). This measurement is based on Atacama Large Millimeter/sub-millimeter Array (ALMA) cycle 4 and 5 observations of the 12CO(2–1) emission line with a spatial resolution of 58 × 32 pc2 (0.18 arcsec × 0.1 arcsec). This resolution, combined with a channel width of 10 km s−1, allows us to well resolve the radius of the black hole sphere of influence (measured as RSOI = 316 pc  =  0.98 arcsec), where we detect a clear Keplerian increase of the rotation velocities. NGC 0383 has a kinematically relaxed, smooth nuclear molecular gas disc with weak ring/spiral features. We forward model the ALMA data cube with the Kinematic Molecular Simulation (KinMS) tool and a Bayesian Markov Chain Monte Carlo method to measure an SMBH mass of (4.2 ± 0.7) × 109 M⊙, a F160W-band stellar mass-to-light ratio that varies from 2.8 ± 0.6 M⊙/L$_{\odot ,\, \mathrm{F160W}}$ in the centre to 2.4 ± 0.3 M⊙$/\rm L_{\odot ,\, \mathrm{F160W}}$ at the outer edge of the disc and a molecular gas velocity dispersion of 8.3 ± 2.1 km s−1(all 3σ uncertainties). We also detect unresolved continuum emission across the full bandwidth, consistent with synchrotron emission from an active galactic nucleus. This work demonstrates that low-J CO emission can resolve gas very close to the SMBH ($\approx 140\, 000$ Schwarzschild radii) and hence that the molecular gas method is highly complimentary to megamaser observations, as it can probe the same emitting material.


Rejuvenated galaxies with very old bulges at the origin of the bending of the main sequence and of the ‘green valley’

Monthly Notices of the Royal Astronomical Society Oxford University Press 489 (2019) 1265-1290

C Mancini, E Daddi, S Juneau, A Renzini, G Rodighiero, M Cappellari, L Rodríguez-Muñoz, D Liu, M Pannella, I Baronchelli, A Franceschini, P Bergamini, C D’Eugenio, A Puglisi

We investigate the nature of star-forming galaxies with reduced specific star formation rate (sSFR) and high stellar masses, those ‘green valley’ objects that seemingly cause a reported bending, or flattening, of the star-forming main sequence. The fact that such objects host large bulges recently led some to suggest that the internal formation of bulges was a late event that induced the sSFRs of massive galaxies to drop in a slow downfall, and thus the main sequence to bend. We have studied in detail a sample of 10 galaxies at 0.45 < z < 1 with secure SFR from Herschel, deep Keck optical spectroscopy, and HST imaging from CANDELS allowing us to perform multiwavelength bulge to disc decomposition, and to derive star formation histories for the separated bulge and disc components. We find that the bulges hosted in these systems below main sequence are virtually all maximally old, with ages approaching the age of the Universe at the time of observation, while discs are young (〈 T50〉 ∼ 1.5 Gyr). We conclude that, at least based on our sample, the bending of the main sequence is, for a major part, due to rejuvenation, and we disfavour mechanisms that postulate the internal formation of bulges at late times. The very old stellar ages of our bulges suggest a number density of early-type galaxies at z = 1–3 higher than actually observed. If confirmed, this might represent one of the first direct validations of hierarchical assembly of bulges at high redshifts.


The impact of AGN on stellar kinematics and orbits in simulated massive galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 489 (2019) 2702-2722

M Frigo, T Naab, M Hirschmann, E Choi, R Davé, RS Somerville, D Krajnovic, M Cappellari

We present a series of 10 × 2 cosmological zoom simulations of the formation of massive galaxies with and without a model for active galactic nucleus (AGN) feedback. Differences in stellar population and kinematic properties are evaluated by constructing mock integral field unit maps. The impact of the AGN is weak at high redshift when all systems are mostly fast rotating and disc-like. After z ∼ 1 the AGN simulations result in lower mass, older, less metal rich, and slower rotating systems with less discy isophotes – in general agreement with observations. 2D kinematic maps of in situ and accreted stars show that these differences result from reduced in-situ star formation due to AGN feedback. A full analysis of stellar orbits indicates that galaxies simulated with AGN are typically more triaxial and have higher fractions of x-tubes and box orbits and lower fractions of z-tubes. This trend can also be explained by reduced late in-situ star formation. We introduce a global parameter, ξ3, to characterize the anticorrelation between the third-order kinematic moment h3 and the line-of-sight velocity (Vavg/σ), and compare to ATLAS3D observations. The kinematic correlation parameter ξ3 might be a useful diagnostic for large integral field surveys as it is a kinematic indicator for intrinsic shape and orbital content.


The data analysis pipeline for the SDSS-IV MaNGA IFU galaxy survey: Overview

Astronomical Journal American Astronomical Society 158 (2019) 231

KB Westfall, M Cappellari, MA Bershady


Six new supermassive black hole mass determinations from adaptive-optics assisted SINFONI observations

Astronomy and Astrophysics EDP Sciences 625 (2019) A62

S Thater, D Krajnovic, M Cappellari, PT De Zeeuw, TA Davis, RM McDermid, M Sarzi


Detecting radio-AGN signatures in red geysers

Astrophysical Journal Institute of Physics 869 (2018) 117-

D Bizyaev, K Masters, D Thomas, C Li, RA Riffel, K Bundy, W Rujopakarn, E Cheung, M Cappellari, F Belfiore, R Yan, T Heckman, J Greene, K Westfall, K Rubin, N Drory, D Law, K Zhang, J Gelfand, M Bershady, N Roy

A new class of quiescent galaxies harboring possible AGN-driven winds has been discovered using spatially resolved optical spectroscopy from the ongoing SDSS-IV MaNGA survey. These galaxies, termed “red geysers”, constitute 5 - 10% of the local quiescent population and are characterized by narrow bisymmetric patterns in ionized gas emission features. Cheung et al. argued that these galaxies host large-scale AGN-driven winds that may play a role in suppressing star formation at late times. In this work, we test the hypothesis that AGN activity is ultimately responsible for the red geyser phenomenon. We compare the nuclear radio activity of the red geysers to a matched control sample with similar stellar mass, redshift, rest frame NUV -r color, axis ratio and presence of ionized gas. We have used the 1.4 GHz radio continuum data from VLA FIRST survey to stack the radio flux from the red geyser and control samples. In addition to a 3 times higher FIRST detection rate, we find that red geysers have a 5σ higher level of average radio flux than control galaxies. After restricting to rest-frame NUV - r color > 5 and checking mid-IR WISE photometry, we rule out star formation contamination and conclude that red geysers are associated with more active AGN. Red geysers and a possibly-related class with disturbed Hα emission account for 40% of all radio-detected red galaxies with log (M*/M⊙) < 11. Our results support a picture in which episodic AGN activity drives large-scale-relatively weak ionized winds that may provide a feedback mechanism for many early-type galaxies.


A quartet of black holes and a missing duo: probing the low end of the M-BH-sigma relation with the adaptive optics assisted integral-field spectroscopy

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 477 (2018) 3030-3064

D Krajnovic, M Cappellari, RM McDermid, S Thater, K Nyland, PT de Zeeuw, J Falcon-Barroso, S Khochfar, H Kuntschner, M Sarzi, LM Young


SDSS-IV MaNGA: Stellar angular momentum of about 2300 galaxies: unveiling the bimodality of massive galaxy properties

Monthly Notices of the Royal Astronomical Society Oxford University Press 477 (2018) 4711–4737-

M Cappellari, MT Graham, S Mao, H Li, M Bershady, D Bizyaev, J Brinkmann, K Bundy, N Drory, K Pan, D Thomas, DA Wake, A-M Weijmans, KB Westfall, R Yan

We measure λRe, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ∈, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the MaNGA survey, the largest such sample to date. We use the (λRe; ∈) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λRe measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λRe . Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λRe; ∈) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λRe and ∈ < 0:4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90° in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above a stellar mass of 2 x 10^11 M⊙ where a significant number of high-mass fast rotators also exist.


The KMOS Cluster Survey (KCS). II. The effect of environment on the structural properties of massive cluster galaxies at redshift 1.39 < z < 1.61

Astrophysical Journal American Astronomical Society 856 (2018) 8

RP Saglia, A Beifiori, J Stott, JT Mendel, A Galametz, R Bender, DJ Wilman, M Cappellari, JCC Chan, R Davies, R Houghton, L Prichard, I Lewis, R Sharples, M Wegner

We present results on the structural properties of massive passive galaxies in three clusters at 1.39 < z < 1.61 from the KMOS Cluster Survey. We measure light-weighted and mass-weighted sizes from optical and near-infrared Hubble Space Telescope imaging and spatially resolved stellar mass maps. The rest-frame R-band sizes of these galaxies are a factor of ∼2-3 smaller than their local counterparts. The slopes of the relation between the stellar mass and the light-weighted size are consistent with recent studies in clusters and the field. Their mass-weighted sizes are smaller than the rest-frame R-band sizes, with an average mass-weighted to light-weighted size ratio that varies between ∼0.45 and 0.8 among the clusters. We find that the median light-weighted size of the passive galaxies in the two more evolved clusters is ∼24% larger than that for field galaxies, independent of the use of circularized effective radii or semimajor axes. These two clusters also show a smaller size ratio than the less evolved cluster, which we investigate using color gradients to probe the underlying gradients. The median color gradients are ∇z - H ∼ -0.4 mag dex -1 , twice the local value. Using stellar populations models, these gradients are best reproduced by a combination of age and metallicity gradients. Our results favor the minor merger scenario as the dominant process responsible for the observed galaxy properties and the environmental differences at this redshift. The environmental differences support that clusters experience accelerated structural evolution compared to the field, likely via an epoch of enhanced minor merger activity during cluster assembly.


The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 235 (2018) ARTN 42

B Abolfathi, DS Aguado, G Aguilar, CA Prieto, A Almeida, TT Ananna, F Anders, SF Anderson, BH Andrews, B Anguiano, A Aragon-Salamanca, M Argudo-Fernandez, E Armengaud, M Ata, E Aubourg, V Avila-Reese, C Badenes, S Bailey, C Balland, KA Barger, J Barrera-Ballesteros, C Bartosz, F Bastien, D Bates, F Baumgarten, J Bautista, R Beaton, TC Beers, F Belfiore, CF Bender, M Bernardi, MA Bershady, F Beutler, JC Bird, D Bizyaev, GA Blanc, MR Blanton, M Blomqvist, AS Bolton, M Boquien, J Borissova, J Bovy, CAB Diaz, WN Brandt, J Brinkmann, JR Brownstein, K Bundy, AJ Burgasser, E Burtin, NG Busca, CI Canas, M Cano-Diaz, M Cappellari, R Carrera, AR Casey, BC Sodi, Y Chen, B Cherinka, C Chiappini, PD Choi, D Chojnowski, C-H Chuang, H Chung, N Clerc, RE Cohen, JM Comerford, J Comparat, JC do Nascimento, L da Costa, M-C Cousinou, K Covey, JD Crane, I Cruz-Gonzalez, K Cunha, GDS Ilha, GJ Damke, J Darling, DJW Jr, K Dawson, MAC de Icaza Lizaola, A de la Macorra, S de la Torre, N de Lee, V de Sainte Agathe, AD Machado, F Dell'Agli, T Delubac, AM Diamond-Stanic, J Donor, JJ Downes, N Drory, HDMD Bourboux, CJ Duckworth, T Dwelly, J Dyer, G Ebelke, AD Eigenbrot, DJ Eisenstein, YP Elsworth, E Emsellem, M Eracleous, G Erfanianfar, S Escoffier, X Fan, EF Alvar, JG Fernandez-Trincado, RF Cirolini, D Feuillet, A Finoguenov, SW Fleming, A Font-Ribera, G Freischlad, P Frinchaboy, H Fu, YG Maqueo Chew, L Galbany, AEG Perez, R Garcia-Dias, DA Garcia-Hernandez, LA Garma Oehmichen, P Gaulme, J Gelfand, H Gil-Marin, BA Gillespie, D Goddard, JI Gonzalez Hernandez, V Gonzalez-Perez, K Grabowski, PJ Green, CJ Grier, A Gueguen, H Guo, J Guy, A Hagen, P Hall, P Harding, S Hasselquist, S Hawley, CR Hayes, F Hearty, S Hekker, J Hernandez, HH Toledo, DW Hogg, K Holley-Bockelmann, JA Holtzman, J Hou, B-C Hsieh, JAS Hunt, TA Hutchinson, HS Hwang, CE Jimenez Angel, JA Johnson, A Jones, H Jonsson, E Jullo, FS Khan, K Kinemuchi, D Kirkby, CC Kirkpatrick, F-S Kitaura, GR Knapp, J-P Kneib, JA Kollmeier, I Lacerna, RR Lane, D Lang, DR Law, J-M Le Goff, Y-B Lee, H Li, C Li, J Lian, Y Liang, M Lima, L Lin, D Long, S Lucatello, B Lundgren, JT Mackereth, CL MacLeod, S Mahadevan, MAG Maia, S Majewski, C Maraston, V Mariappan, R Marques-Chaves, T Masseron, KL Masters, RM McDermid, ID McGreer, M Melendez, S Meneses-Goytia, A Merloni, MR Merrifield, S Meszaros, A Meza, I Minchev, D Minniti, E-M Mueller, F Muller-Sanchez, D Muna, RR Munoz, AD Myers, P Nair, K Nandra, M Ness, JA Newman, RC Nichol, DL Nidever, C Nitschelm, P Noterdaeme, J O'Connell, RJ Oelkers, A Oravetz, D Oravetz, EA Ortiz, Y Osorio, Z Pace, N Padilla, N Palanque-Delabrouille, PA Palicio, H-A Pan, K Pan, T Parikh, I Paris, C Park, S Peirani, M Pellejero-Ibanez, S Penny, WJ Percival, I Perez-Fournon, P Petitjean, MM Pieri, M Pinsonneault, A Pisani, F Prada, A Prakash, AB de Andrade Queiroz, MJ Raddick, A Raichoor, SB Rembold, H Richstein, RA Riffel, H-W Rix, AC Robin, SR Torres, C Roman-Zuniga, AJ Ross, G Rossi, J Ruan, R Ruggeri, J Ruiz, M Salvato, AG Sanchez, SF Sanchez, JS Almeida, JR Sanchez-Gallego, FA Santana Rojas, BX Santiago, RP Schiavon, JS Schimoia, E Schlafly, D Schlegel, DP Schneider, WJ Schuster, A Schwope, H-J Seo, A Serenelli, S Shen, Y Shen, M Shetrone, M Shull, VS Aguirre, JD Simon, M Skrutskie, A Slosar, R Smethurst, V Smith, J Sobeck, G Somers, BJ Souter, D Souto, A Spindler, DV Stark, K Stassun, M Steinmetz, D Stello, T Storchi-Bergmann, A Streblyanska, GS Stringfellow, G Suarez, J Sun, L Szigeti, M Taghizadeh-Popp, MS Talbot, B Tang, C Tao, J Tayar, M Tembe, J Teske, AR Thakar, D Thomas, P Tissera, R Tojeiro, C Tremonti, NW Troup, M Urry, O Valenzuela, R Van den Bosch, J Vargas-Gonzalez, M Vargas-Magana, JA Vazquez, S Villanova, N Vogt, D Wake, Y Wang, BA Weaver, A-M Weijmans, DH Weinberg, KB Westfall, DG Whelan, E Wilcots, V Wild, RA Williams, J Wilson, WM Wood-Vasey, D Wylezalek, T Xiao, R Yan, M Yang, JE Ybarra, C Yeche, N Zakamska, O Zamora, P Zarrouk, G Zasowski, K Zhang, C Zhao, G-B Zhao, Z Zheng, Z Zheng, Z-M Zhou, G Zhu, JC Zinn, H Zou


SDSS-IV MaNGA: The intrinsic shape of slow rotator early-type galaxies

Astrophysical Journal Letters American Astronomical Society 863 (2018) L19

M Cappellari, MT Graham, E Emsellem, RJ Long, H Li, S Mao

By inverting the distributions of galaxies' apparent ellipticities and misalignment angles (measured around the projected half-light radius R e) between their photometric and kinematic axes, we study the intrinsic shape distribution of 189 slow rotator early-type galaxies with stellar masses 2 × 1011 M ⊙ < M * < 2 × 1012 M ⊙, extracted from a sample of about 2200 galaxies with integral-field stellar kinematics from the data release 14 (DR14) of the fourth-generation Sloan Digital Sky Survey IV (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) integral field unit (IFU) survey. Thanks to the large sample of slow rotators, Graham et al. showed that there is clear structure in the misalignment angle distribution, with two peaks at both 0° and 90° misalignment (characteristic of oblate and prolate rotation, respectively). Here we invert the observed distribution from Graham et al. The large sample allows us to go beyond the known fact that slow rotators are weakly triaxial and to place useful constraints on their intrinsic triaxiality distribution (around 1 R e) for the first time. The shape inversion is generally non-unique. However, we find that, for a wide set of model assumptions, the observed distribution clearly requires a dominant triaxial-oblate population. For some of our models, the data suggest a minor triaxial-prolate population, but a dominant prolate population is ruled out.


Stellar populations and star formation histories of the nuclear star clusters in six nearby galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press 480 (2018) 1973–1998-

N Kacharov, N Neumayer, AC Seth, M Cappellari, R McDermid, CJ Walcher, T Böker

The majority of spiral and elliptical galaxies in the Universe host very dense and compact stellar systems at their centres known as nuclear star clusters (NSCs). In this work we study the stellar populations and star formation histories (SFH) of the NSCs of six nearby galaxies with stellar masses ranging between 2 and 8×109M⊙ (four late-type spirals and two early-types) with high resolution spectroscopy. Our observations are taken with the X-Shooter spectrograph at the VLT. We make use of an empirical simple stellar population (SSP) model grid to fit composite stellar populations to the data and recover the SFHs of the nuclei. We find that the nuclei of all late-type galaxies experienced a prolonged SFH, while the NSCs of the two early-types are consistent with SSPs. The NSCs in the late-type galaxies sample appear to have formed a significant fraction of their stellar mass already more than 10 Gyr ago, while the NSCs in the two early-type galaxies are surprisingly younger. Stars younger than 100 Myr are present in at least two nuclei: NGC 247 & NGC 7793, with some evidence for young star formation in NGC 300’s NSC. The NSCs of the spirals NGC 247 and NGC 300 are consistent with prolonged in situ star formation with a gradual metallicity enrichment from ∼−1.5 dex more than 10 Gyr ago, reaching super-Solar values few hundred Myr ago. NGC 3621 appears to be very metal rich already in the early Universe and NGC 7793 presents us with a very complex SFH, likely dominated by merging of various massive star clusters coming from different environments.


Recovering stellar population parameters via two full-spectrum fitting algorithms in the absence of model uncertainties

Monthly Notices of the Royal Astronomical Society Oxford University Press 478 (2018) 2633–2649-

S Mao, H Li, Y Lu, J Ge, M Cappellari, R Yan

Using mock spectra based on Vazdekis/MILES library fitted within the wavelength region 3600-7350\AA, we analyze the bias and scatter on the resulting physical parameters induced by the choice of fitting algorithms and observational uncertainties, but avoid effects of those model uncertainties. We consider two full-spectrum fitting codes: pPXF and STARLIGHT, in fitting for stellar population age, metallicity, mass-to-light ratio, and dust extinction. With pPXF we find that both the bias in the population parameters and the scatter in the recovered logarithmic values follows the expected trend. The bias increases for younger ages and systematically makes recovered ages older, M∗/Lr larger and metallicities lower than the true values. For reference, at S/N=30, and for the worst case (t=108yr), the bias is 0.06 dex in M∗/Lr, 0.03 dex in both age and [M/H]. There is no significant dependence on either E(B-V) or the shape of the error spectrum. Moreover, the results are consistent for both our 1-SSP and 2-SSP tests. With the STARLIGHT algorithm, we find trends similar to pPXF, when the input E(B-V)<0.2 mag. However, with larger input E(B-V), the biases of the output parameter do not converge to zero even at the highest S/N and are strongly affected by the shape of the error spectra. This effect is particularly dramatic for youngest age, for which all population parameters can be strongly different from the input values, with significantly underestimated dust extinction and [M/H], and larger ages and M∗/Lr. Results degrade when moving from our 1-SSP to the 2-SSP tests. The STARLIGHT convergence to the true values can be improved by increasing Markov Chains and annealing loops to the "slow mode". For the same input spectrum, pPXF is about two order of magnitudes faster than STARLIGHT's "default mode" and about three order of magnitude faster than STARLIGHT's "slow mode".


The black hole in the most massive ultracompact dwarf galaxy M59-UCD3

Astrophysical Journal American Astronomical Society 858 (2018) 102

CP Ahn, AC Seth, M Cappellari, E al.

We examine the internal properties of the most massive ultracompact dwarf galaxy (UCD), M59-UCD3, by combining adaptive-optics-assisted near-IR integral field spectroscopy from Gemini/NIFS and Hubble Space Telescope (HST) imaging. We use the multiband HST imaging to create a mass model that suggests and accounts for the presence of multiple stellar populations and structural components. We combine these mass models with kinematics measurements from Gemini/NIFS to find a best-fit stellar mass-to-light ratio (M/L) and black hole (BH) mass using Jeans anisotropic models (JAMs), axisymmetric Schwarzschild models, and triaxial Schwarzschild models. The best-fit parameters in the JAM and axisymmetric Schwarzschild models have BHs between 2.5 and 5.9 million solar masses. The triaxial Schwarzschild models point toward a similar BH mass but show a minimum χ 2 at a BH mass of ~0. Models with a BH in all three techniques provide better fits to the central V rms profiles, and thus we estimate the BH mass to be ${4.2}_{-1.7}^{+2.1}\times {10}^{6}$ M ⊙ (estimated 1σ uncertainties). We also present deep radio imaging of M59-UCD3 and two other UCDs in Virgo with dynamical BH mass measurements, and we compare these to X-ray measurements to check for consistency with the fundamental plane of BH accretion. We detect faint radio emission in M59cO but find only upper limits for M60-UCD1 and M59-UCD3 despite X-ray detections in both these sources. The BH mass and nuclear light profile of M59-UCD3 suggest that it is the tidally stripped remnant of a ~109–1010 M ⊙ galaxy.


Nearby Early-type Galactic Nuclei at High Resolution: Dynamical Black Hole and Nuclear Star Cluster Mass Measurements

ASTROPHYSICAL JOURNAL 858 (2018) ARTN 118

DD Nguyen, AC Seth, N Neumayer, S Kamann, KT Voggel, M Cappellari, A Picotti, PM Nguyen, T Boker, V Debattista, N Caldwell, R McDermid, N Bastian, CC Ahn, R Pechetti

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