Browsing by Author "Cote, Patrick"

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    An evolutionary continuum from nucleated dwarf galaxies to star clusters
    (2023) Wang, Kaixiang; Peng, Eric W.; Liu, Chengze; Mihos, J. Christopher; Cote, Patrick; Ferrarese, Laura; Taylor, Matthew A.; Blakeslee, John P.; Cuillandre, Jean-Charles; Duc, Pierre-Alain; Guhathakurta, Puragra; Gwyn, Stephen; Ko, Youkyung; Lancon, Ariane; Lim, Sungsoon; Macarthur, Lauren A.; Puzia, Thomas; Roediger, Joel; Sales, Laura V.; Sanchez-Janssen, Ruben; Spengler, Chelsea; Toloba, Elisa; Zhang, Hongxin; Zhu, Mingcheng
    Systematic studies1-4 have revealed hundreds of ultra-compact dwarf galaxies (UCDs5) in the nearby Universe. With half-light radii rh of approximately 10-100 parsecs and stellar masses M* approximate to 106-108 solar masses, UCDs are among the densest known stellar systems6. Although similar in appearance to massive globular clusters7, the detection of extended stellar envelopes4,8,9, complex star formation histories10, elevated mass-to-light ratio11,12 and supermassive black holes13-16 suggest that some UCDs are remnant nuclear star clusters17 of tidally stripped dwarf galaxies18,19, or even ancient compact galaxies20. However, only a few objects have been found in the transient stage of tidal stripping21,22, and this assumed evolutionary path19 has never been fully traced by observations. Here we show that 106 galaxies in the Virgo cluster have morphologies that are intermediate between normal, nucleated dwarf galaxies and single-component UCDs, revealing a continuum that fully maps this morphological transition and fills the 'size gap' between star clusters and galaxies. Their spatial distribution and redder colour are also consistent with stripped satellite galaxies on their first few pericentric passages around massive galaxies23. The 'ultra-diffuse' tidal features around several of these galaxies directly show how UCDs are forming through tidal stripping and that this evolutionary path can include an early phase as a nucleated ultra-diffuse galaxy24,25. These UCDs represent substantial visible fossil remnants of ancient dwarf galaxies in galaxy clusters, and more low-mass remnants probably remain to be found.
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    Dark Matter in Ultra-diffuse Galaxies in the Virgo Cluster from Their Globular Cluster Populations
    (2018) Toloba, Elisa; Lim, Sungsoon; Peng, Eric; Sales, Laura V.; Guhathakurta, Puragra; Mihos, J. Christopher; Cote, Patrick; Boselli, Alessandro; Cuillandre, Jean-Charles; Ferrarese, Laura; Gwyn, Stephen; Lancon, Ariane; Munoz, Roberto; Puzia, Thomas H.
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    Detection of a White Dwarf Companion to a Blue Straggler Star in the Outskirts of Globular Cluster NGC 5466 with the Ultraviolet Imaging Telescope (UVIT)
    (2019) Sahu, Snehalata; Subramaniam, Annapurni; Simunovic, Mirko; Postma, J.; Cote, Patrick; Rao, N. Kameswera; Geller, Aaron M.; Leigh, Nathan; Shara, Michael; Puzia, Thomas H.; Stetson, Peter B.
    We report the discovery of a hot white dwarf (WD) companion to a blue straggler star (BSS) in the globular cluster (GC) NGC 5466, based on observations from the Ultra-Violet Imaging Telescope (UVIT) on board AstroSat. The Spectral Energy Distribution (SED) of the Far-UV detected BSS NH 84 was constructed by combining the flux measurements from four filters of UVIT, with GALEX, GALA, and other ground-based observations. The SED of NH 84 reveals the presence of a hot companion to the BSS. The temperature and radius of the BSS (T-eff = 8000(-250)(+1000) K, R/R-circle dot = 1.44 +/- 0.05) derived from Gemini spectra and SED fitting using Kurucz atmospheric models are consistent with each other. The temperature and radius of the hotter companion of NH 84 (T-eff = 32,000 +/- 2000 K, R/R-circle dot = 0.021 +/- 0.007) derived by fitting Koester WD models to the SED suggest that it is likely to be a hot WD. The radial velocity derived from the spectra along with the proper motion from GALA DR2 confirms NH 84 to be a kinematic member of the cluster. This is the second detection of a BSS-WD candidate in a GC, and the first in the outskirts of a low-density GC. The location of this BSS in NGC 5466 along with its dynamical age supports the mass-transfer pathway for BSS formation in low-density environments.
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    Evidence for the Hierarchical Formation of the Galactic Spheroid
    (2000) Cote, Patrick; Minniti, D.
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    Evidence for the Rapid Formation of Low-mass Early-type Galaxies in Dense Environments
    (2016) Liu, Yiqing; Peng, Eric W.; Blakeslee, John; Cote, Patrick; Ferrarese, Laura; Jordán Colzani, Andrés Cristóbal; Puzia, Thomas H.; Tolobar, Elisa; Zhang, Hongxin
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    Fresh Insights on the Kinematics of M49's Globular Cluster System with MMT/Hectospec Spectroscopy
    (2021) Taylor, Matthew A.; Ko, Youkyung; Cote, Patrick; Ferrarese, Laura; Peng, Eric W.; Zabludoff, Ann; Roediger, Joel; Sanchez-Janssen, Ruben; Hendel, David; Chilingarian, Igor; Liu, Chengze; Spengler, Chelsea; Zhang, Hongxin
    We present the first results of an MMT/Hectospec campaign to measure the kinematics of globular clusters (GCs) around M49-the brightest galaxy in the Virgo galaxy cluster, which dominates the Virgo B subcluster. The data include kinematic tracers beyond 95 kpc (similar to 5.2 effective radii) for M49 for the first time, enabling us to achieve three key insights reported here. First, beyond similar to 20 '-30 ' (similar to 100-150 kpc), the GC kinematics sampled along the minor photometric axis of M49 become increasingly hotter, indicating a transition from GCs related to M49 to those representing the Virgo B intra-cluster medium. Second, there is an anomaly in the line-of-sight radial velocity dispersion (sigma ( r,los)) profile in an annulus similar to 10-15 ' (similar to 50-90 kpc) from M49 in which the kinematics cool by Delta sigma ( r,los) approximate to 150 km s(-1) relative to those in- or outward. The kinematic fingerprint of a previous accretion event is hinted at in projected phase-space, and we isolate GCs that both give rise to this feature, and are spatially co-located with two prominent stellar shells in the halo of M49. Third, we find a subsample of GCs with velocities representative of the dwarf galaxy VCC 1249 that is currently interacting with M49. The spatial distribution of these GCs closely resembles the morphology of VCC 1249's isophotes, indicating that several of these GCs are likely in the act of being stripped from the dwarf during its passage through M49's halo. Taken together, these results point toward the opportunity of witnessing ongoing giant halo assembly in the depths of a cluster environment.
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    Globular Cluster UVIT Legacy Survey (GlobULeS) - I. FUV-optical colour-magnitude diagrams for eight globular clusters
    (2022) Sahu, Snehalata; Subramaniam, Annapurni; Singh, Gaurav; Yadav, Ramakant; Valcarce, Aldo R.; Choudhury, Samyaday; Rani, Sharmila; Prabhu, Deepthi S.; Chung, Chul; Cote, Patrick; Leigh, Nathan; Geller, Aaron M.; Chatterjee, Sourav; Rao, N. Kameswara; Bandyopadhyay, Avrajit; Shara, Michael; Dalessandro, Emanuele; Pandey, Gajendra; Postma, Joesph E.; Hutchings, John; Simunovic, Mirko; Stetson, Peter B.; Thirupathi, Sivarani; Puzia, Thomas; Sohn, Young-Jong
    We present the first results of eight globular clusters (GCs) from the AstroSat/UVIT Legacy Survey programme GlobULeS based on the observations carried out in two far-ultraviolet (FUV) filters (F148W and F169M). The FUV-optical and FUV-FUV colour-magnitude diagrams (CMDs) of GCs with the proper motion membership were constructed by combining the Ultra-Violet Imaging Telescope (UVIT) data with Hubble Space Telescope (HST) UV Globular Cluster Survey data for inner regions and Gaia Early Data Release for regions outside the HST's field. We detect sources as faint as F148W similar to 23.5 mag, which are classified based on their locations in CMDs by overlaying stellar evolutionary models. The CMDs of eight GCs are combined with the previous UVIT studies of three GCs to create stacked FUV-optical CMDs to highlight the features/peculiarities found in the different evolutionary sequences. The FUV (F148W) detected stellar populations of 11 GCs comprise 2816 horizontal branch (HB) stars [190 extreme HB (EHB) candidates], 46 post-HB (pHB), 221 blue straggler stars (BSSs), and 107 white dwarf (WD) candidates. We note that the blue HB colour extension obtained from F148W - G colour and the number of FUV detected EHB candidates are strongly correlated with the maximum internal helium (He) variation within each GC, suggesting that the FUV-optical plane is the most sensitive to He abundance variations in the HB. We discuss the potential science cases that will be addressed using these catalogues including HB morphologies, BSSs, pHB, and WD stars.
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    Globular Cluster UVIT Legacy Survey (GlobULeS). III. Omega Centauri in Far-ultraviolet
    (2022) Prabhu, Deepthi S.; Subramaniam, Annapurni; Sahu, Snehalata; Chung, Chul; Leigh, Nathan W. C.; Dalessandro, Emanuele; Chatterjee, Sourav; Rao, N. Kameswara; Shara, Michael; Cote, Patrick; Choudhury, Samyaday; Pandey, Gajendra; Valcarce, Aldo A. R.; Singh, Gaurav; Postma, Joesph E.; Rani, Sharmila; Bandyopadhyay, Avrajit; Geller, Aaron M.; Hutchings, John; Puzia, Thomas; Simunovic, Mirko; Sohn, Young-Jong; Thirupathi, Sivarani; Yadav, Ramakant Singh
    We present the first comprehensive study of the most massive globular cluster, Omega Centauri, in the far-ultraviolet (FUV), extending from the center to similar to 28% of the tidal radius using the Ultraviolet Imaging Telescope on board AstroSat. A comparison of the FUV-optical color-magnitude diagrams with available canonical models reveals that horizontal branch (HB) stars bluer than the knee (hHBs) and the white dwarfs (WDs) are fainter in the FUV by similar to 0.5 mag than model predictions. They are also fainter than their counterparts in M13, another massive cluster. We simulated HB with at least five subpopulations, including three He-rich populations with a substantial He enrichment of Y up to 0.43 dex, to reproduce the observed FUV distribution. We find the He-rich younger subpopulations to be radially more segregated than the He-normal older ones, suggesting an in situ enrichment from older generations. The omega Cen hHBs span the same T (eff) range as their M13 counterparts, but some have smaller radii and lower luminosities. This may suggest that a fraction of omega Cen hHBs are less massive than those of M13, similar to the result derived from earlier spectroscopic studies of outer extreme HB stars. The WDs in omega Cen and M13 have similar luminosity-radius-T (eff) parameters, and 0.44-0.46 M (circle dot) He-core WD model tracks evolving from progenitors with Y = 0.4 dex are found to fit the majority of these. This study provides constraints on the formation models of omega Cen based on the estimated range in age, [Fe/H], and Y (in particular) for the HB stars.
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    Pristine dwarf galaxy survey - I. A detailed photometric and spectroscopic study of the very metal-poor Draco II satellite
    (2018) Longeard, Nicolas; Martin, Nicolas; Starkenburg, Else; Ibata, Rodrigo A.; Collins, Michelle L. M.; Geha, Marla; Laevens, Benjamin P. M.; Rich, R. Michael; Aguado, David S.; Arentsen, Anke; Carlberg, Raymond G.; Cote, Patrick; Hill, Vanessa; Jablonka, Pascale; Gonzalez Hernandez, Jonay I.; Navarro, Julio F.; Sanchez-Janssen, Ruben; Tolstoy, Eline; Venn, Kim A.; Youakim, Kris
    We present a detailed study of the faint Milky Way satellite Draco II (Dra II) from deep CFHT/MegaCam broad-band g and i photometry and narrow-band metallicity-sensitive CaliK observations, along with follow-up Keck II/DEIMOS multi-object spectroscopy. Forward modelling of the deep photometry allows us to refine the structural and photometric properties of Dra II: the distribution of stars in colour-magnitude space implies Dra II is old (13.5 +/- 0.5 Gyr), very metal-poor, very faint (L-v = 180(-72)(+124) L-circle dot), and at a distance d = 21.5 +/- 0.4 kpc. The narrow-band, metallicity-sensitive Cal-IK Pristine photometry confirms this very low metallicity ([Fe/H] = -2.7 +/- 0.1 dex). Even though our study benefits from a doubling of the spectroscopic sample size compared to previous investigations, the velocity dispersion of the system is still only marginally resolved (sigma(vr) < 5.9 km s(-1) at the 95 per cent confidence level) and confirms that Dra II is a dynamically cold stellar system with a large recessional velocity (< v(r)> = -342.5(-1.2)(+1.1)km s(-)1). We further show that the spectroscopically confirmed members of Dra II have a mean proper motion of (mu(alpha)*, mu(delta)) = (1.26 +/- 0.27, 0.94 +/- 0.28) mas/yr in the Gaia DR2 data, which translates to an orbit with a pericentre and an apocentre of 21.3(-1.0)(+0.7) and 153.8(-34.7)(+56.7) kpc, respectively. Taken altogether, these properties favour the scenario of Dra II being a potentially disrupting dwarf galaxy. The low-significance extra-tidal features we map around the satellite tentatively support this scenario.
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    Supermassive black holes in a mass-limited galaxy sample
    (2023) Byrne, Zachary; Drinkwater, Michael J.; Baumgardt, Holger; Blyth, David; Cote, Patrick; Luetzgendorf, Nora; Spengler, Chelsea; Ferrarese, Laura; Mahajan, Smriti; Pfeffer, Joel; Sweet, Sarah
    The observed scaling relations between supermassive black hole masses and their host galaxy properties indicate that supermassive black holes influence the evolution of galaxies. However, the scaling relations may be affected by selection biases. We propose to measure black hole masses in a mass-limited galaxy sample including all non-detections to inpro v e constraints on galaxy mass - black hole mass scaling relations and test for selection bias. We use high-spatial resolution spectroscopy from the Keck and Gemini telescopes, and the Jeans Anisotropic Modelling method to measure black hole masses in early-type galaxies from the Virgo Cluster. We present four new black hole masses and one upper limit in our mass-selected sample of galaxies of galaxy mass (1.0-3.2) x10(10) M-circle dot. This brings the total measured to 11 galaxies out of a full sample of 18 galaxies, allowing us to constrain scaling relations. We calculate a lower limit for the average black hole mass in our sample of 3.7 x 10(7) M-circle dot. This is at an average galaxy stellar mass of (1.81 +/- 0.14) x 10(10) M-circle dot and an average bulge mass of (1.31 +/- 0.15) x 10(10) M-circle dot. This lower limit shows that black hole masses in early-type galaxies are not strongly affected by selection biases.
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    SURFACE BRIGHTNESS FLUCTUATIONS IN THE HUBBLE SPACE TELESCOPE ACS/WFC F814W BANDPASS AND AN UPDATE ON GALAXY DISTANCES
    (2010) Blakeslee, John P.; Cantiello, Michele; Mei, Simona; Cote, Patrick; DeGraaff, Regina Barber; Ferrarese, Laura; Jordan, Andres; Peng, Eric W.; Tonry, John L.; Worthey, Guy
    We measure surface brightness fluctuation (SBF) magnitudes in the F814W filter and (g(475)-I-814) colors for nine bright early-type Fornax cluster galaxies imaged with the Hubble Space Telescope Advanced Camera for Surveys (ACS). The goal is to achieve the first systematic SBF calibration for the ACS/F814W bandpass. Because of its much higher throughput, F814W is more efficient for SBF studies of distant galaxies than the ACS/F850LP bandpass that has been used to study nearby systems. Over the color range spanned by the sample galaxies, 1.06 < (g(475)-I-814) < 1.32 (AB mag), the dependence of SBF magnitude (m) over bar (814) on (g(475)-I-814) is linear to a good approximation, with slope similar to 2. When the F850LP SBF distance measurements from the ACS Fornax Cluster Survey are used to derive absolute (M) over bar (814) magnitudes, the dependence on (g(475)-I-814) becomes extremely tight, with a slope of 1.8 +/- 0.2 and a scatter of 0.03 mag. The small observed scatter indicates both that the estimated random errors are correct and that the intrinsic deviations from the SBF-color relation are strongly correlated between the F814W and F850LP bandpasses, as expected. The agreement with predictions from stellar population models is good, both in slope and zero point, indicating that our mean Fornax distance of 20 Mpc is accurate. The models predict curvature in the relation beyond the color limits of our sample; thus, the linear calibration should not be extrapolated naively. In the appendices, we reconsider the Tonry ground-based and Jensen NICMOS SBF distance catalogs; we provide a correction formula to ameliorate the small apparent bias in the former and the offset needed to make the latter consistent with other SBF studies. We also tabulate two new SBF distances to galaxies observed in the ACS Virgo Cluster Survey.
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    The ACS Fornax Cluster Survey. III. Globular Cluster Specific Frequencies of Early-type Galaxies
    (2019) Liu, Yiqing; Peng, Eric W.; Jordan, Andres; Blakeslee, John P.; Cote, Patrick; Ferrarese, Laura; Puzia, Thomas H.
    The globular cluster (GC) specific frequency (SN), defined as the number of GCs per unit galactic luminosity, represents the efficiency of GC formation (and survival) compared to field stars. Despite the naive expectation that star cluster formation should scale directly with star formation, this efficiency varies widely across galaxies. To explore this variation, we measure the z-band GC specific frequency (S-N,S- z) for 43 early-type galaxies (ETGs) from the Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) Fornax Cluster Survey. Combined with the homogeneous measurements of S-N,S- z in 100 ETGs from the HST/ACS Virgo Cluster Survey from Peng et al., we investigate the dependence of S-N,S- z on mass and environment over a range of galaxy properties. We find that S-N,S- z behaves similarly in the two galaxy clusters, despite the clusters' order-of-magnitude difference in mass density. The S-N,S- z is low in intermediate-mass ETGs (-20 < M-z < -23) and increases with galaxy luminosity. It is elevated at low masses, on average, but with a large scatter driven by galaxies in dense environments. The densest environments with the strongest tidal forces appear to strip the GC systems of low-mass galaxies. However, in low-mass galaxies that are not in strong tidal fields, denser environments correlate with enhanced GC formation efficiencies. Normalizing by inferred halo masses, the GC mass fraction, eta = (3.36 +/- 0.2) x 10(-5), is constant for ETGs with stellar masses M-star <= 3 x 10(10) M-circle dot, in agreement with previous studies. The lack of correlation between the fraction of GCs and the nuclear light implies only a weak link between the infall of GCs and the formation of nuclei.
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    THE ACS FORNAX CLUSTER SURVEY. IV. DEPROJECTION OF THE SURFACE BRIGHTNESS PROFILES OF EARLY-TYPE GALAXIES IN THE VIRGO AND FORNAX CLUSTERS: INVESTIGATING THE "CORE/POWER-LAW DICHOTOMY"
    (2011) Glass, Lisa; Ferrarese, Laura; Cote, Patrick; Jordan, Andres; Peng, Eric; Blakeslee, John P.; Chen, Chin-Wei; Infante, Leopoldo; Mei, Simona; Tonry, John L.; West, Michael J.
    Although early observations with the Hubble Space Telescope (HST) pointed to a sharp dichotomy among early-type galaxies in terms of the logarithmic slope gamma' of their central surface brightness profiles, several studies in the past few years have called this finding into question. In particular, recent imaging surveys of 143 early-type galaxies belonging to the Virgo and Fornax Clusters using the Advanced Camera for Surveys (ACS) on board HST have not found a dichotomy in gamma', but instead a systematic progression from central luminosity deficit to excess relative to the inward extrapolation of the best-fitting global Sersic model. Given that earlier studies also found that the dichotomy persisted when analyzing the deprojected density profile slopes, we investigate the distribution of the three-dimensional luminosity density profiles of the ACS Virgo and Fornax Cluster Survey galaxies. Having fitted the surface brightness profiles with modified Sersic models, we then deproject the galaxies using an Abel integral and measure the inner slopes gamma(3D) of the resulting luminosity density profiles at various fractions of the effective radius R-e. We find no evidence of a dichotomy, but rather, a continuous variation in the central luminosity profiles as a function of galaxy magnitude. We introduce a parameter, Delta(3D), that measures the central deviation of the deprojected luminosity profiles from the global Sersic fit, showing that this parameter varies smoothly and systematically along the luminosity function.
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    THE ACS FORNAX CLUSTER SURVEY. XI. CATALOG OF GLOBULAR CLUSTER CANDIDATES
    (2015) Jordán Colzani, Andrés Cristóbal; Peng, Eric W.; Blakeslee, John P.; Cote, Patrick; Eyheramendy Duerr, Susana; Ferrarese, Laura
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    The ACS Fornax Cluster Survey. XII. Diffuse Star Clusters in Early-type Galaxies
    (2016) Liu, Yiqing; Peng, Eric W.; Lim, Sungsoon; Jordán Colzani, Andrés Cristóbal; Blakeslee, John; Cote, Patrick; Ferrarese, Laura; Pattarakijwanich, Petchara
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    The ACS Fornax Cluster survey.: I.: Introduction to the survey and data reduction procedures
    (2007) Jordan, Andres; Blakeslee, John P.; Cote, Patrick; Ferrarese, Laura; Infante, Leopoldo; Mei, Simona; Merritt, David; Peng, Eric W.; Tonry, John L.; West, Michael J.
    The Fornax Cluster is a conspicuous cluster of galaxies in the southern hemisphere and the second largest collection of early-type galaxies within less than or similar to 20 Mpc after the Virgo Cluster. In this paper, we present a brief introduction to the ACS Fornax Cluster Survey - a program to image, in the F475W (g(475)) and F850LP (z(850)) bandpasses, 43 early-type galaxies in Fornax using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Combined with a companion survey of Virgo, the ACS Virgo Cluster Survey, this represents the most comprehensive imaging survey to date of early-type galaxies in cluster environments in terms of depth, spatial resolution, sample size, and homogeneity. We describe the selection of the program galaxies, their basic properties, and the main science objectives of the survey, which include the measurement of luminosities, colors, and structural parameters for globular clusters associated with these galaxies, an analysis of their isophotal properties and surface brightness profiles, and an accurate calibration of the surface brightness fluctuation distance indicator. Finally, we discuss the data reduction procedures adopted for the survey.
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    The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
    (2006) Cote, Patrick; Jordán Colzani, Andrés Cristóbal
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    The Color Gradients of the Globular Cluster Systems in M87 and M49
    (2022) Wu, Yiming; Liu, Chengze; Peng, Eric W.; Ko, Youkyung; Cote, Patrick; Jain, Rashi; Ferrarese, Laura; Yang, Xiaohu; Lancon, Ariane; Puzia, Thomas; Lim, Sungsoon
    Combining data from the ACS Virgo Cluster Survey and the Next Generation Virgo cluster Survey, we extend previous studies of color gradients of the globular cluster (GC) systems of the two most massive galaxies in the Virgo cluster, M87 and M49, to radii of similar to 15 R (e) (similar to 200 kpc for M87 and similar to 250 kpc for M49, where R (e) is the effective radius). We find significant negative color gradients, i.e., becoming bluer with increasing distance, out to these large radii. The gradients are driven mainly by the outward decrease in the ratio of red to blue GC numbers. The color gradients are also detected out to similar to 15 R (e) in the red and blue subpopulations of GCs taken separately. In addition, we find a negative color gradient when we consider the satellite low-mass elliptical galaxies as a system, i.e., the satellite galaxies closer to the center of the host galaxy usually have redder color indices, for both their stars and their GCs. According to the "two phase" formation scenario of massive early-type galaxies, the host galaxy accretes stars and GCs from low-mass satellite galaxies in the second phase. So an accreted GC system naturally inherits the negative color gradient present in the satellite population. This can explain why the color gradient of the GC system can still be observed at large radii after multiple minor mergers.
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    THE COLOR-MAGNITUDE RELATION FOR METAL-POOR GLOBULAR CLUSTERS IN M87: CONFIRMATION FROM DEEP HST/ACS IMAGING
    (2009) Peng, Eric W.; Jordan, Andres; Blakeslee, John P.; Mieske, Steffen; Cote, Patrick; Ferrarese, Laura; Harris, William E.; Madrid, Juan P.; Meurer, Gerhardt R.
    Metal-poor globular clusters (GCs) are our local link to the earliest epochs of star formation and galaxy building. Studies of extragalactic GC systems using deep, high-quality imaging have revealed a small but significant slope to the color-magnitude relation for metal-poor GCs in a number of galaxies. We present a study of the M87 GC system using deep, archival HST/ACS imaging with the F606W and F814W filters, in which we find a significant color-magnitude relation for the metal-poor GCs. The slope of this relation in the I versus V-I color-magnitude diagram (gamma(I) =-0.024 +/- 0.006) is perfectly consistent with expectations based on previously published results using data from the ACS Virgo Cluster Survey. The relation is driven by the most luminous GCs, those with M(I) less than or similar to -10, and its significance is largest when fitting metal-poor GCs brighter than M(I) = -7.8, a luminosity which is similar to 1 mag fainter than our fitted Gaussian mean for the luminosity function (LF) of blue, metalpoor GCs (similar to 0.8 mag fainter than the mean for all GCs). These results indicate that there is a mass scale at which the correlation begins, and is consistent with a scenario where self-enrichment drives a mass-metallicity relationship. We show that previously measured half-light radii of M87 GCs from best-fit PSF-convolved King models are consistent with the more accurate measurements in this study, and we also explain how the color magnitude relation for metal-poor GCs is real and cannot be an artifact of the photometry. We fit Gaussian and evolved Schechter functions to the luminosity distribution of GCs across all colors, as well as divided into blue and red subpopulations, finding that the blue GCs have a brighter mean luminosity and a narrower distribution than the red GCs. Finally, we present a catalog of astrometry and photometry for 2250 M87 GCs.