We present a two-dimensional (2D) fitting algorithm (GALFIT, ver. 3) with new capabilities to study the structural components of galaxies and other astronomical objects in digital images. Our technique improves on previous 2D fitting algorithms by allowing for irregular, curved, logarithmic and power-law spirals, ring, and truncated shapes in otherwise traditional parametric functions like the Sersic, Moffat, King, Ferrer, etc., profiles. One can mix and match these new shape features freely, with or without constraints, and apply them to an arbitrary number of model components of numerous profile types, so as to produce realistic-looking galaxy model images. Yet, despite the potential for extreme complexity, the meaning of the key parameters like the Sersic index, effective radius, or luminosity remains intuitive and essentially unchanged. The new features have an interesting potential for use to quantify the degree of asymmetry of galaxies, to quantify low surface brightness tidal features beneath and beyond luminous galaxies, to allow more realistic decompositions of galaxy subcomponents in the presence of strong rings and spiral arms, and to enable ways to gauge the uncertainties when decomposing galaxy subcomponents. We illustrate these new features by way of several case studies that display various levels of complexity.

https://iopscience.iop.org/article/10.1088/0004-6256/139/6/2097/pdf

Detailed decomposition of galaxy images. ii. beyond axisymmetric models

We derive improved versions of the relations between supermassive black hole mass (M BH) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M-σ and M-L relations), based on 49 M BH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (e0) in both relations. We find log(M BH/M) = α + βlog(σ/200 km s-1) with (α, β, e0) = (8.12 0.08, 4.24 0.41, 0.44 0.06) for all galaxies and (α, β, e0) = (8.23 0.08, 3.96 0.42, 0.31 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-σ relation, and further implies that there may be substantial selection bias in studies of the evolution of the M-σ relation. We estimate the M-L relationship as log(M BH/M) = α + βlog(LV /1011 L V) of (α, β, e0) = (8.95 0.11, 1.11 0.18, 0.38 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole's sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals. © 2009. The American Astronomical Society.

https://iopscience.iop.org/article/10.1088/0004-637X/698/1/198/pdf

The M-σ and M-L Relations in Galactic Bulges, and Determinations of Their Intrinsic Scatter

We derive improved versions of the relations between supermassive black hole mass (M_BH) and host-galaxy bulge velocity dispersion (sigma) and luminosity (L) (the M-sigma and M-L relations), based on 49 M_BH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (epsilon_0) in both relations. We find log(M_BH / M_sun) = alpha + beta * log(sigma / 200 km/s) with (alpha, beta, epsilon_0) = (8.12 +/- 0.08, 4.24 +/- 0.41, 0.44 +/- 0.06) for all galaxies and (alpha, beta, epsilon_0) = (8.23 +/- 0.08, 3.96 +/- 0.42, 0.31 +/- 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-sigma relation, and further implies that there may be substantial selection bias in studies of the evolution of the M-sigma relation. We estimate the M-L relationship as log(M_BH / M_sun) = alpha + beta * log(L_V / 10^11 L_sun,V) of (alpha, beta, epsilon_0) = (8.95 +/- 0.11, 1.11 +/- 0.18, 0.38 +/- 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole's sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.

The M-sigma and M-L Relations in Galactic Bulges and Determinations of their Intrinsic Scatter

New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges These provide enough leverage to show that S?rsic log I r 1/n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation Two kinds of departures are seen at small radii All 10 of our ellipticals with total absolute magnitudes MVT ? ?2166 have cuspy cores?missing light?at small radii Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless (dry) mergers All 17 ellipticals with ?2154 ? MVT ? ?1553 do not have cores We find a new distinct component in these galaxies: all coreless ellipticals in our sample have extra light at the center above the inward extrapolation of the outer S?rsic profile In large ellipticals, the excess light is spatially resolved and resembles the central components predicted in numerical simulations of mergers of galaxies that contain gas In the simulations, the gas dissipates, falls toward the center, undergoes a starburst, and builds a compact stellar component that, as in our observations, is distinct from the S?rsic-function main body of the elliptical But ellipticals with extra light also contain supermassive BHs We suggest that the starburst has swamped core scouring by binary BHs That is, we interpret extra light components as a signature of formation in dissipative (wet) mergers Besides extra light, we find three new aspects to the (E-E) dichotomy into two types of elliptical galaxies Core galaxies are known to be slowly rotating, to have relatively anisotropic velocity distributions, and to have boxy isophotes We show that they have S?rsic indices n > 4 uncorrelated with MVT  They also are ?-element enhanced, implying short star-formation timescales And their stellar populations have a variety of ages but mostly are very old Extra light ellipticals generally rotate rapidly, are more isotropic than core Es, and have disky isophotes We show that they have n 3 ? 1 almost uncorrelated with MVT and younger and less ?-enhanced stellar populations These are new clues to galaxy formation We suggest that extra light ellipticals got their low S?rsic indices by forming in relatively few binary mergers, whereas giant ellipticals have n > 4 because they formed in larger numbers of mergers of more galaxies at once plus later heating during hierarchical clustering We confirm that core Es contain X-ray-emitting gas whereas extra light Es generally do not This leads us to suggest why the E-E dichotomy arose If energy feedback from active galactic nuclei (AGNs) requires a working surface of hot gas, then this is present in core galaxies but absent in extra light galaxies We suggest that AGN energy feedback is a strong function of galaxy mass: it is weak enough in small Es not to prevent merger starbursts but strong enough in giant Es and their progenitors to make dry mergers dry and to protect old stellar populations from late star formation Finally, we verify that there is a strong dichotomy between elliptical and spheroidal galaxies Their properties are consistent with our understanding of their different formation processes: mergers for ellipticals and conversion of late-type galaxies into spheroidals by environmental effects and by energy feedback from supernovae In an appendix, we develop machinery to get realistic error estimates for S?rsic parameters even when they are strongly coupled And we discuss photometric dynamic ranges necessary to get robust results from S?rsic fits

https://iopscience.iop.org/article/10.1088/0067-0049/182/1/216/pdf

Structure and formation of elliptical and spheroidal galaxies

The transformations that take place in late‐type galaxies in the environment of rich clusters of galaxies at \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $z=0$ \end{document} are reviewed. From the handful of late‐type galaxies that inhabit local clusters, whether they were formed in situ and survived as such, avoiding transformation or even destruction, or if they are newcomers that have recently fallen in from outside, we can learn an important lesson on the latest stages of galaxy evolution. We start by reviewing t...

https://iopscience.iop.org/article/10.1086/500691/pdf

Environmental Effects on Late-Type Galaxies in Nearby Clusters

Structure and origin of S0 galaxies. II. Disk-to-bulge ratios.

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Structure and origin of S0 galaxies. II. Disk-to-bulge ratios.