J/ApJ/716/942 Bulges of nearby galaxies with Spitzer (Fisher+, 2010) ================================================================================ Bulges of nearby galaxies with Spitzer: scaling relations in pseudobulges and classical bulges. Fisher D.B., Drory N. =2010ApJ...716..942F ================================================================================ ADC_Keywords: Galaxies, nearby ; Photometry, infrared ; Morphology Keywords: galaxies: bulges - galaxies: evolution - galaxies: formation - galaxies: fundamental parameters - galaxies: structure Abstract: We investigate scaling relations of bulges using bulge-disk decompositions at 3.6um and present bulge classifications for 173 E-Sd galaxies within 20Mpc. Pseudobulges and classical bulges are identified using Sersic index, Hubble Space Telescope morphology, and star formation activity (traced by 8um emission). In the near-IR pseudobulges have n_b_<2 and classical bulges have n_b_>2, as found in the optical. Sersic index and morphology are essentially equivalent properties for bulge classification purposes. We confirm, using a much more robust sample, that the Sersic index of pseudobulges is uncorrelated with other bulge structural properties, unlike for classical bulges and elliptical galaxies. Also, the half-light radius of pseudobulges is not correlated with any other bulge property. We also find a new correlation between surface brightness and pseudobulge luminosity; pseudobulges become more luminous as they become more dense. Description: We use data from Spitzer to perform bulge-disk decompositions at 3.6um, where the data are less affected by gradients in dust and stellar populations than in the optical bands. Also, we use 8um mid-IR data to estimate star formation rates. We also wish to compare the location of pseudobulges and classical bulges in parameter space to that of elliptical galaxies. We therefore include a set of elliptical galaxies as a control sample from Kormendy et al. (2009, Cat. J/ApJS/182/216). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 41 145 Sample galaxy properties table2.dat 92 145 Derived parameters -------------------------------------------------------------------------------- See also: VII/155 : Third Reference Cat. of Bright Galaxies (RC3) (de Vaucouleurs+ 1991) VII/145 : Nearby Galaxies Catalogue (NBG) (Tully 1988) J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009) J/AJ/136/773 : Structure of classical bulges and pseudobulges (Fisher+, 2008) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Name Galaxy name 10- 16 A7 --- Type Morphological type taken from RC3 18- 22 F5.2 Mpc Dist Distance 24 I1 --- r_Dist Distance reference (1) 26- 31 F6.2 mag BMag Absolute B-band magnitude 33- 36 F4.2 mag B-V ? B-V color index 38- 41 F4.2 [pc] logD25 Isophotal diameter -------------------------------------------------------------------------------- Note (1): Distance reference as follows: 1 = Tully & Fisher 1988cng..book.....T (see also VII/145); 2 = Tonry et al. 2001ApJ...546..681T; 3 = de Vaucouleurs et al. 1991, Cat. VII/155 (RC3) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Name Galaxy name 10 A1 --- B [P/C/ ] Bulge morphology: P=pseudobulge, C=classical bulge 12- 15 F4.2 --- nb The bulge Sersic index 17- 20 F4.2 --- e_nb nb uncertainty 22- 27 F6.2 mag M3.6 3.6um magnitude of the bulge (M_3.6_^Sersic^) 29- 32 F4.2 mag e_M3.6 M3.6 uncertainty 34- 37 F4.2 [pc] log(re) Log of the half-light radius r_e_ 39- 42 F4.2 [pc] e_log(re) log(re) uncertainty 44- 48 F5.2 mag/arcsec2 mue The average surface brightness within the half-light radius (2) 50- 53 F4.2 mag/arcsec2 e_mue mue uncertainty 55- 59 F5.2 mag/arcsec2 mud Surface brightness ({mu}^disk^_0,3.6_) 61- 64 F4.2 mag/arcsec2 e_mud mud uncertainty 66- 69 F4.2 [pc] log(h) Log of the scale length of the outer disk 71- 74 F4.2 [pc] e_log(h) log(h) uncertainty 76- 81 F6.2 mag M8 ? 8um magnitude of the bulge, dominated by dust emission (M_8,dust_) (3) 83- 87 F5.2 mag 3.6-8 ? M_3.6-M_8.0_ mid-IR color index 89- 92 F4.2 mag e_3.6-8 ? 3.6-8 uncertainty -------------------------------------------------------------------------------- Note (2): The average surface brightness within the half-light radius, <{mu}_e_> is given by <{mu}_e_>=m_3.6_+2.5log({pi}r_e_^2^) where m_3.6_ is the magnitude in 3.6um. See section 3.2 for further details. Note (3): We calculate M_8,dust_ using the relation from Helou et al. (2004ApJS..154..253H), where M_8,dust_=-2.5xlog_10_(L_8_-0.232xL_3.6_) where L_3.6_ is the bulge luminosity at 3.6um. See section 6.1 for further details. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Emmanuelle Perret [CDS] 31-May-2012