DRAFT VERSION OCTOBER 25, 2018 Preprint typeset using LATEX style emulateapj v. 08/22/09 A QUINTET OF BLACK HOLE MASS DETERMINATIONS1 KAYHAN GULTEKIN¨ 2,DOUGLAS O. RICHSTONE2,KARL GEBHARDT3,TOD R. LAUER4,JASON PINKNEY5, M. C. ALLER6,RALF BENDER7,ALAN DRESSLER8, S. M. FABER9,ALEXEI V. FILIPPENKO10,RICHARD GREEN11,LUIS C. HO8,JOHN KORMENDY3, CHRISTOS SIOPIS12 Draft version October 25, 2018 ABSTRACT We report five new measurements of central black hole masses based on STIS and WFPC2 observations with the Hubble Space Telescope and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy’s sphere of influence based on the predicted value of the black hole mass from the +1:5 8 M–s relation. We find masses for the following galaxies: NGC 3585, MBH = 3:4−0:6 × 10 M ; NGC 3607, +0:4 8 +0:7 8 +0:3 8 MBH = 1:2−0:4 × 10 M ; NGC 4026, MBH = 2:1−0:4 × 10 M ; and NGC 5576, MBH = 1:8−0:4 × 10 M , +17 6 all significantly excluding MBH = 0. For NGC 3945, MBH = 9−21 × 10 M , which is significantly below predictions from M–s and M–L relations and consistent with MBH = 0, though the presence of a double bar in this galaxy may present problems for our axisymmetric code. Subject headings: black hole physics — galaxies: general — galaxies:nuclei — stellar dynamics 1. INTRODUCTION TO BLACK HOLE MASS MEASUREMENTS have also been derived from stellar proper motions in our This paper is the latest in a campaign to model the cen- Galaxy (Genzel et al. 2000; Ghez et al. 2005), from mega- tral regions of galaxies to determine masses of putative black maser measurements of gas disks around central black holes holes from images and spectra taken with the Hubble Space (e.g., Miyoshi et al. 1995), and from gas velocity measure- Telescope (HST). The discovery of the presence of a massive ments (e.g., Barth et al. 2001). Reverberation mapping has dark object (probably a black hole) in almost all galaxies hav- also been used to find virial products in variable active galac- ing bulges, and the scaling relations found versus host-galaxy tic nuclei (AGNs; e.g., Peterson et al. 2004). properties, will stand as one of the important legacies of this Direct dynamical masses are the foundation for all scal- great observatory. ing relations used to infer black hole masses in active galax- Masses were first determined from stellar velocity mea- ies; all measures of black hole mass are derived from the di- surements made with ground-based telescopes having the best rect, dynamical measurements. Indirect mass indicators, such possible spatial resolution, together with isotropic kinematic as AGN line widths, are calibrated to reverberation mapping models (Dressler & Richstone 1988). When combined with measurements (Bentz et al. 2006), which are themselves nor- the spatial resolution of HST, this method has become the malized against the direct dynamical measurements (Onken standard for black hole mass measurements (e.g., van der et al. 2004). Marel et al. 1998; Gebhardt et al. 2000b). Black hole masses A central goal of a companion paper (Gultekin¨ et al. 2009) is the accurate measurement of the intrinsic or cosmic scat- 1 Based on observations made with the Hubble Space Telescope, obtained ter in the M–s and M-L relationships (Magorrian et al. 1998; at the Space Telescope Science Institute, which is operated by the Associa- Gebhardt et al. 2000a). We have thus chosen to augment the tion of Universities for Research in Astronomy, Inc., under NASA contract existing sample of MBH measurements with new determina- NAS 5-26555. These observations are associated with GO proposals 5999, tions of M for five galaxies selected to fall within a narrow 6587, 6633, 7468, and 9107. BH 2 Department of Astronomy, University of Michigan, Ann Arbor, MI, range in velocity dispersion. Along with results from the lit- 48109; Send correspondence to [email protected]. erature, this provides a number of galaxies in a narrow range arXiv:0901.4162v2 [astro-ph.GA] 1 May 2009 3 Department of Astronomy, University of Texas, Austin, TX, 78712. in velocity dispersion large enough that we may probe the in- 4 National Optical Astronomy Observatory, Tucson, AZ 85726. trinsic scatter in the relation without biases incurred by, for 5 Department of Physics and Astronomy, Ohio Northern University, Ada, example, looking only at residuals to power-law fits. OH 45810. 6 Department of Physics, Institute of Astronomy, ETH Zurich, CH-8093 We present observations of the centers of five early-type Zurich, Switzerland. galaxies in x 2, including HST observations in x 2.3, ground- 7 Universitaets-Sternwarte der Ludwig-Maximilians-Universitat,¨ Schein- based imaging in x 2.4, and ground-based spectra in x 2.5. We erstr. 1, D-81679 Munchen,¨ Germany. report results of dynamical models and black hole masses in 8 Observatories of the Carnegie Institution of Washington, Pasadena, CA x 3, and summarize in x 4. In the Appendix, we provide our 91101. 9 University of California Observatories/Lick Observatory, Board of Stud- data tables. ies in Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064. M 10 Department of Astronomy, University of California, Berkeley, CA 2. OBSERVATIONS FOR NEW BH DETERMINATIONS 94720-3411. 2.1. Observational Sample 11 LBT Observatory, University of Arizona, Tucson, AZ 85721. 12 Institut d’Astronomie et d’Astrophysique, Universite´ Libre de Brux- The five galaxies in this study were selected to come from a elles, B-1050 Bruxelles, Belgium. narrow range in velocity dispersion (180 < s < 200 km s−1) 2 Gultekin¨ et al. based on HyperLEDA13 central velocity dispersion measures 234). Reciprocal dispersion measured using our own wave- (Paturel et al. 2003). We chose this range because (1) it in- length solutions was 0.554 A˚ pixel−1. The distribution of dis- cludes galaxies with MB ≈ −20 mag where both core and persion solutions for a given data set had a s ≈ 1:5 × 10−4 power-law surface-brightness profiles exist and (2) it includes A˚ pixel−1. The average dispersion given in the Handbook for both late- and early-type galaxies. We selected galaxies with G750M is 0.56 A˚ pixel−1. We found a comparison line width distances such that the predicted radius of influence was larger ˚ −1 than 0:001. The radius of influence is defined as of s = 0:45 A = 17:5 km s . Instrumental line widths were measured by fitting Gaussians to emission lines on compari- GMBH son lamp exposures. This gives an estimate of the instrumen- Rinfl ≡ 2 ; (1) s (Rinfl) tal line width for extended sources. We use approximately five lines per exposure, and at least five measurements per where the velocity dispersion s is evaluated at the radius of line. While the comparison lamp exposures were unbinned, influence. This obviously requires an iterative solution, but it the galaxy spectra were binned, which increases the measured converges quickly. The predicted mass comes from the central widths by ∼25% for the 0:001 slit and by ∼ 3% for the 0:002 slit velocity dispersion measurement and the M–s fit of Tremaine at 8561 A.˚ Leitherer et al. (2001, p. 300) give the follow- et al.(2002). ing instrumental line widths for point sources: s=13.3, 15.0, The sample of new galaxies and their properties are pre- 16.7 km s−1 for the first three G750M setups in Table2. The sented in Table1. Distances are calculated assuming a Hubble 00 −1 −1 −1 spatial scale is 0: 05597 pixel for G750M at 8561 A.˚ constant of H0 = 70 km s Mpc . We also provide “Nuker Law” surface-brightness profile parameters as a function of The STIS data reduction was done with our own programs radius given by and FITSIO subroutines (Pence 1998; Pinkney et al. 2003). The raw spectra were extracted from the multidimensional (g−b)=a r g r a FITS file, and a constant fit was subtracted from the over- I (r) = 2(b−g)=aI b 1 + ; (2) scan region to remove the bias level. Because the STIS CCD b r r b has warm and hot pixels that evolve on timescales of . 1 d, which is a broken power-law profile (Lauer et al. 1995). In the dark-current subtraction needs to be accurate. We used addition to the five galaxies whose black hole masses are re- the iterative self-dark method described by Pinkney et al. ported in this paper, we observed five others with HST as part (2003). After flat fielding, we vertically shifted the spectra of the same observing proposal. Two of these (NGC 1374 and to a common dither, combined them, and then rotated. One- NGC 7213) had very low signal-to-noise ratio (S/N). The re- dimensional spectra were extracted from the final spectro- maining three (NGC 2434, NGC 4382, and NGC 7727) will gram using a biweight combination of rows. A 1-pixel wide be presented in a future paper. binning scheme was used near the galaxy center to optimize spatial resolution. We present Gauss–Hermite moments of the 2.2. WFPC2 Imaging velocity profiles in the Appendix. The high-resolution photometry of the central regions of Ground-Based Imaging the galaxies comes from Wide Field Planetary Camera 2 2.4. (WFPC2) observations on HST using filters F555W (V) and CCD images of one of our galaxies, NGC 3945, were ob- F814W (I).