The evolving slope of the stellar mass function at 0.6 ≤ z< 4.5 from deep WFC3 data

Abstract

We used Early Release Science (ERS) observations taken with the Wide Field Camera 3 (WFC3) in the GOODS-S field to study the galaxy stellar mass function (GSMF) at 0.6 ≤ z < 4.5. Deep WFC3 near-IR data (for Y as faint as 27.3, J and H as faint as 27.4 AB mag at 5σ), as well as deep K S (as faint as 25.5 at 5σ) Hawk-I band data, provide an exquisite data set with which determine in an unprecedented way the low-mass end of the GSMF, allowing an accurate probe of masses as low as M * 7.6 × 10 9 M at z ∼ 3. Although the area used is relatively small (∼33 arcmin 2 ), we found generally good agreement with previous studies on the entire mass range. Our results show that the slope of the faint-end increases with redshift, from α = −1.44 ± 0.03 at z ∼ 0.8 to α = −1.86 ± 0.16 at z ∼ 3, although indications exist that it does not steepen further between z ∼ 3 and z ∼ 4. This result is insensitive to any uncertainty in the M * parameter. The steepness of the GSMF faint-end solves the well-known disagreement between the stellar mass density (SMD) and the integrated star-formation history at z > 2. However, we confirm that there appears to be an excess of integrated star formation with respect to the SMD at z < 2, by a factor of ∼2−3. Our comparison of the observations with theoretical predictions shows that the models forecast a greater abundance of low mass galaxies, at least up to z ∼ 3, as well as a dearth of massive galaxies at z ∼ 4 with respect to the data, and that the predicted SMD is generally overestimated at z < ∼ 2.

The interaction-driven starburst contribution to the cosmic star formation rate density

“…Hopkins & Beacom 2006;Fardal et al 2007;Wilkins et al 2008;Santini et al 2012). In principle, these two observables represent independent approaches to studying the mass assembly history from different points of view.…”

Formation of disc galaxies in preheated media: a preventative feedback model

“…Figure 12 shows the predicted number density of galaxies in this stellar mass range as a function of redshift in comparison with observational data. The pink band shows the data compiled in Weinmann et al (2012), and the points with error bars are our own compilation from various recent observations: Baldry, Glazebrook & Driver (2008) and Baldry et al (2012) for local galaxies; Moustakas et al (2013) for galaxies out to z = 1; Santini et al (2012) and Tomczak et al (2013) for galaxies out to z ≈ 3; and Lee et al (2012), González et al (2011) and Stark et al (2013) for galaxies at higher redshifts. The Santini et al results give a higher number density of galaxies in this stellar mass range than the data sets adopted in Weinmann et al In particular, the data of Santini et al show a very steep low-mass end slope at z ≈ 2, leading to an exceptionally high number density at this redshift.…”

Dark-ages reionization and galaxy formation simulation – X. The small contribution of quasars to reionization

“…(i) the observed evolution of the galaxy stellar mass function (Pozzetti et al 2007;Drory et al 2009;Marchesini et al 2009;González et al 2011;Mortlock et al 2011;Santini et al 2012;Ilbert et al 2013;Muzzin et al 2013;Duncan et al 2014;Tomczak et al 2014;Grazian et al 2015;Song et al 2015;Huertas-Company et al 2016;Stefanon et al 2016;Davidzon et al 2017) between z∼0.6 and 7. We note that the observed stellar mass functions, based on a diet Salpeter IMF, a Chabrier (2003) IMF or a Kroupa (2001) IMF, were all converted into a standard Salpeter IMF by adding −0.15, 0.22 or 0.18 dex, respectively, to the logarithm of the stellar masses;…”

“…Galaxy stellar mass functions at z ∼ 7 − 0.6 from the fiducial ( ), M16 ( ) and M16BH ( ) models compared to the observational data ( Pozzetti et al 2007, ×Drory et al 2009, Marchesini et al 2009, •Mortlock et al 2011, González et al 2011, Santini et al 2012, Ilbert et al 2013, Muzzin et al 2013, Tomczak et al 2014, Duncan et al 2014, Song et al 2015, Grazian et al 2015, Huertas-Company et al 2016, Stefanon et al 2016, Davidzon et al 2017. The ratios of M16BH to the M16 result are shown in the bottom subpanels.…”