J/ApJ/744/44 Hα and UV fluxes in nearby galaxies (Weisz+, 2012)
Modeling the effects of star formation histories on Hα and ultraviolet
fluxes in nearby dwarf galaxies.
Weisz D.R., Johnson B.D., Johnson L.C., Skillman E.D., Lee J.C.,
Kennicutt R.C., Calzetti D., van Zee L., Bothwell M.S., Dalcanton J.J.,
Dale D.A., Williams B.F.
<Astrophys. J., 744, 44 (2012)>
=2012ApJ...744...44W 2012ApJ...744...44W
ADC_Keywords: Galaxies, nearby ; Ultraviolet ; Photometry, surface ;
Magnitudes, absolute ; Photometry, H-alpha
Keywords: galaxies: dwarf - galaxies: evolution - galaxies: formation -
galaxies: star formation
Abstract:
We consider the effects of non-constant star formation histories
(SFHs) on Hα and GALEX far-ultraviolet (FUV) star formation rate
(SFR) indicators. Under the assumption of a fully populated Chabrier
initial mass function (IMF), we compare the distribution of
Hα-to-FUV flux ratios from ∼1500 simple, periodic model SFHs
with observations of 185 galaxies from the Spitzer Local Volume Legacy
survey. We find a set of SFH models that are well matched to the data,
such that more massive galaxies are best characterized by nearly
constant SFHs, while low-mass systems experience burst amplitudes of
∼30 (i.e., an increase in the SFR by a factor of 30 over the SFR
during the inter-burst period), burst durations of tens of Myr, and
periods of ∼250 Myr; these SFHs are broadly consistent with the
increased stochastic star formation expected in systems with lower
SFRs. We analyze the predicted temporal evolution of galaxy stellar
mass, R-band surface brightness, Hα-derived SFR, and blue
luminosity, and find that they provide a reasonable match to observed
flux distributions. We find that our model SFHs are generally able to
reproduce both the observed systematic decline and increased scatter
in Hα-to-FUV ratios toward low-mass systems, without invoking
other physical mechanisms.
Description:
Our final sample of 185 galaxies have observations of Hα and
GALEX FUV from 11HUGS (11Mpc Hα and UV Galaxy Survey; Kennicutt
et al. 2008, Cat. J/ApJS/178/247; Lee et al. 2011, Cat. J/ApJS/192/6),
Spitzer IR from LVL (Local Volume Legacy survey; Dale et al. 2009,
Cat. J/ApJ/703/517), and optical broadband imaging from either
SDSS-DR7 (Cat. II/294) or LVL.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 45 186 Basic properties of the Local Volume Legacy galaxies
--------------------------------------------------------------------------------
See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011)
J/ApJ/733/74 : GALEX-SDSS properties of local galaxies (Lemonias+, 2011)
J/ApJ/734/L22 : ACS Nearby Galaxy Survey Treasury (Williams+, 2011)
J/ApJ/714/1256 : Far-IR star formation rate indicators (Calzetti+, 2010)
J/ApJ/706/599 : Hα and UV SFR in the local volume (Lee+, 2009)
J/ApJ/706/553 : Fluxes in nearby star-forming galaxies (Boquien+, 2009)
J/ApJ/703/1672 : Far-IR and Hα fluxes in galaxies (Kennicutt+, 2009)
J/ApJ/703/517 : The Spitzer Local Volume Legacy: IR photometry (Dale+, 2009)
J/ApJ/693/1821 : The Spitzer infrared nearby galaxies survey (Dale+, 2009)
J/ApJS/178/247 : Hα and [NII] survey in local 11 Mpc (Kennicutt+, 2008)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Galaxy name
13- 17 F5.2 [Msun] logM* Log of galaxy stellar mass
19- 22 F4.2 [Lsun/kpc2] logSigR Log of R-band surface brightness
24- 29 F6.2 mag BMag Absolute B-band magnitude
31- 36 F6.3 [Msun/yr] logSFR Log of Hα star formation rate (1)
38- 43 F6.3 [-] logR+k Log of Hα/FUV fluxes plus κ (2)
45 I1 --- r_Name Optical observation source code reference (3)
--------------------------------------------------------------------------------
Note (1): Not been corrected for attenuation.
Note (2): Flux ratios have been dust corrected as detailed in Section 2.1. The
values in this column are listed relative to the value of fiducial,
whose value is reflected by the constant κ=-13.17.
Note (3): Reference code as follows:
1 = SDSS DR7 (Abazajian et al. 2009, cat. II/294);
2 = LVL (Local Volume Legacy survey; van Zee et al. 2012, in prep.).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 28-May-2013