21 research outputs found
Evolution of Galaxy Star Formation and Metallicity: Impact on Double Compact Object Mergers
In this paper, we study the impact of different galaxy statistics and empirical metallicity scaling relations on the
merging rates and properties of compact object binaries. Firstly, we analyze the similarities and differences of
using the star formation rate functions versus stellar mass functions as galaxy statistics for the computation of
cosmic star formation rate density. We then investigate the effects of adopting the Fundamental Metallicity
Relation versus a classic Mass Metallicity Relation to assign metallicity to galaxies with given properties. We find
that when the Fundamental Metallicity Relation is exploited, the bulk of the star formation occurs at relatively high
metallicities, even at high redshift; the opposite holds when the Mass Metallicity Relation is employed, since in this
case the metallicity at which most of the star formation takes place strongly decreases with redshift. We discuss the
various reasons and possible biases giving rise to this discrepancy. Finally, we show the impact of these different
astrophysical prescriptions on the merging rates and properties of compact object binaries; specifically, we present
results for the redshift-dependent merging rates and for the chirp mass and time delay distributions of the merging
binaries
Unveiling the nature of 11 dusty star-forming galaxies at the peak of cosmic star formation history
We present a panchromatic study of 11 (sub-)millimetre selected DSFGs with spectroscopically confirmed redshift (1.5 < zspec < 3) in the GOODS-S field, with the aim of constraining their astrophysical properties (e.g. age, stellar mass, dust, and gas content) and characterizing their role in the context of galaxy evolution. The multiwavelength coverage of GOODS-S, from X-rays to radio band, allow us to model galaxy SED by using cigale z with a novel approach, based on a physical motivated modelling of stellar light attenuation by dust. Median stellar mass (∼ 6.5 × 1010 M·) and SFR (∼ 241 M· yr-1) are consistent with galaxy main sequence at z ∼2. The galaxies are experiencing an intense and dusty burst of star formation (medianLIR ∼ 2 × 1012L·), with a median age of 750 Myr. The high median content of interstellar dust (Mdust ∼ 5 × 108 M·) suggests a rapid enrichment of the ISM (on time-scales ∼108 yr). We derived galaxy total and molecular gas content from CO spectroscopy and/or Rayleigh-Jeans dust continuum (1010 Mgas/M· 1011), depleted over a typical time-scale τdepl ∼200 Myr. X-ray and radio luminosities (LX = 1042-1044 erg s-1,L1.5, {
m GHz}}=1030-C1 erg s-1,L 6, rm GHz=1029-C0 erg s-1) suggest that most of the galaxies hosts an accreting radio-silent/quiet SMBH. This evidence, along with their compact multiwavelength sizes (median rALMA ∼rVLA = 1.8 kpc, rHST = 2.3 kpc) measured from high-resolution imaging (θres 1 arcsec), indicates these objects as the high-z star-forming counterparts of massive quiescent galaxies, as predicted e.g. by the in situ scenario. Four objects show some signatures of a forthcoming/ongoing AGN feedback, which is thought to trigger the morphological transition from star-forming discs to ETGs
An ALMA view of 11 dusty star-forming galaxies at the peak of cosmic star formation history
We present the ALMA view of 11 main-sequence dusty star-forming galaxies (DSFGs) (sub-)millimetre selected in the Great Observatories Origins Survey South (GOODS-S) field and spectroscopically confirmed to be at the peak of cosmic star formation history (z ∼2). Our study combines the analysis of galaxy spectral energy distribution with ALMA continuum and CO spectral emission by using ALMA Science Archive products at the highest spatial resolution currently available for our sample (Δθ 1 arcsec). We include galaxy multiband images and photometry (in the optical, radio, and X-rays) to investigate the interlink between dusty, gaseous, and stellar components and the eventual presence of AGN. We use multiband sizes and morphologies to gain an insight on the processes that lead galaxy evolution, e.g. gas condensation, star formation, AGN feedback. The 11 DSFGs are very compact in the (sub-)millimetre (median rALMA = 1.15 kpc), while the optical emission extends to larger radii (median rH/rALMA = 2.05). CO lines reveal the presence of a rotating disc of molecular gas, but we cannot exclude the presence of interactions and/or molecular outflows. Images at higher (spectral and spatial) resolution are needed to disentangle from the possible scenarios. Most of the galaxies are caught in the compaction phase, when gas cools and falls into galaxy centre, fuelling the dusty burst of star formation and the growing nucleus. We expect these DSFGs to be the high-z star-forming counterparts of massive quiescent galaxies. Some features of CO emission in three galaxies are suggestive of forthcoming/ongoing AGN feedback, which is thought to trigger the morphological transition from star-forming discs to early-type galaxies
Evidence of extended [CII] and dust emission in local dwarf galaxies
The evolution of dwarf galaxies is dramatically affected by gaseous and dusty
outflows, which can easily deprive their interstellar medium of the material
needed for the formation of new stars, simultaneously enriching their
surrounding circumgalactic medium (CGM). In this letter, we present the first
evidence of extended [CII] 158 m line and dust continuum emission in local
dwarf galaxies hosting star-formation-driven outflows. By stacking the [CII],
far-infrared, and near-UV (NUV) emission obtained from Herschel and GALEX data,
we derived the average radial profiles, and compared the spatial extension of
gas, dust, and stellar activity in dwarf galaxies. We find that [CII] and dust
emissions are comparable to each other, and more extended than the NUV
continuum. The [CII] size is in agreement with that measured for
star-forming galaxies, suggesting that similar mechanisms could be at the
origin of the observed atomic carbon reservoir around local and high-
sources. The cold dust follows the [CII] emission, going beyond the stellar
continuum as opposed to what is typically observed in the early Universe where
measurements can be affected by the poor sensitivity and faintness of dust
emission in the CGM of high- galaxies. We attribute the extended [CII] and
dust continuum emission to the presence of galactic outflows. As local dwarf
galaxies are considered analogs of primordial sources, we expect that
comparable feedback processes can be at the origin of the observed [CII] halos
at , dominating over other possible formation mechanisms.Comment: 8 pages, 4 figures, accepted for publication in A&
In pursuit of giants: I. The evolution of the dust-to-stellar mass ratio in distant dusty galaxies
The dust-to-stellar mass ratio (Mdust/M?) is a crucial, albeit poorly constrained, parameter for improving our understanding of the
complex physical processes involved in the production of dust, metals, and stars in galaxy evolution. In this work, we explore trends
of Mdust/M? with dierent physical parameters and using observations of 300 massive dusty star-forming galaxies detected with
ALMA up to z 5. Additionally, we interpret our findings with dierent models of dusty galaxy formation. We find that Mdust/M?
evolves with redshift, stellar mass, specific star formation rates, and integrated dust size, but that evolution is dierent for mainsequence
galaxies than it is for starburst galaxies. In both galaxy populations, Mdust/M? increases until z 2, followed by a roughly
flat trend towards higher redshifts, suggesting ecient dust growth in the distant universe. We confirm that the inverse relation
between Mdust/M? and M? holds up to z 5 and can be interpreted as an evolutionary transition from early to late starburst phases.
We demonstrate that the Mdust/M? in starbursts reflects the increase in molecular gas fraction with redshift and attains the highest
values for sources with the most compact dusty star formation. State-of-the-art cosmological simulations that include self-consistent
dust growth have the capacity to broadly reproduce the evolution of Mdust/M? in main-sequence galaxies, but underestimating it in
starbursts. The latter is found to be linked to lower gas-phase metallicities and longer dust-growth timescales relative to observations.
The results of phenomenological models based on the main-sequence and starburst dichotomy as well as analytical models that include
recipes for rapid metal enrichment are consistent with our observations. Therefore, our results strongly suggest that high Mdust/M?
is due to rapid dust grain growth in the metal-enriched interstellar medium. This work highlights the multi-fold benefits of using
Mdust/M? as a diagnostic tool for: (1) disentangling main-sequence and starburst galaxies up to z 5; (2) probing the evolutionary
phase of massive objects; and (3) refining the treatment of the dust life cycle in simulations
Variation of optical and infrared properties of galaxies with their surface brightness
Although low surface brightness galaxies (LSBs) contribute a large fraction
to the number density of galaxies, their properties are still poorly known.
LSBs are often considered dust poor, based only on a few studies. We use, for
the first time, a large sample of LSBs and high surface brightness galaxies
(HSBs) with deep observational data to study their dust properties as a
function of surface brightness. Our sample consists of 1631 optically selected
galaxies at from the North Ecliptic Pole (NEP) wide field. We use the
large set of data available in this field, from UV to FIR. We measured the
optical size and the surface brightness of the targets, and analyzed their
spectral energy distribution using the CIGALE fitting code. We found that the
specific star formation rate and specific infrared luminosity (total infrared
luminosity per stellar mass) remain mostly flat as a function of surface
brightness for both LSBs and HSBs that are star-forming but decline steeply for
the quiescent galaxies. The majority of LSBs in our sample have negligible dust
attenuation (A mag), except for about 4% of them that show
significant attenuation with a mean A of 0.8 mag. We found that these
LSBs also have a high -band mass-to-light ratio (
M/L), and show similarity to the extreme giant LSBs from
the literature, indicating a possibly higher dust attenuation in giant LSBs as
well. This work provides a large catalog of LSBs and HSBs with detailed
measurements of their several optical and infrared physical properties. Our
results suggest that the dust content of LSBs is more varied than previously
thought, with some of them having significant attenuation making them fainter
than their intrinsic value. This will have serious implications for the
observation and analysis of LSBs with current/upcoming surveys like JWST and
LSST.Comment: 16 pages, 12 figures, accepted for publication in A&
An ALMA view of 11 dusty star-forming galaxies at the peak of cosmic star formation history
We present the ALMA view of 11 main-sequence dusty star-forming galaxies (DSFGs) (sub-)millimetre selected in the Great Observatories Origins Survey South (GOODS-S) field and spectroscopically confirmed to be at the peak of cosmic star formation history (z ~ 2). Our study combines the analysis of galaxy spectral energy distribution with ALMA continuum and CO spectral emission by using ALMA Science Archive products at the highest spatial resolution currently available for our sample (Δθ ≲ 1 arcsec). We include galaxy multiband images and photometry (in the optical, radio, and X-rays) to investigate the interlink between dusty, gaseous, and stellar components and the eventual presence of AGN. We use multiband sizes and morphologies to gain an insight on the processes that lead galaxy evolution, e.g. gas condensation, star formation, AGN feedback. The 11 DSFGs are very compact in the (sub-)millimetre (median rALMA = 1.15 kpc), while the optical emission extends to larger radii (median rH/rALMA = 2.05). CO lines reveal the presence of a rotating disc of molecular gas, but we cannot exclude the presence of interactions and/or molecular outflows. Images at higher (spectral and spatial) resolution are needed to disentangle from the possible scenarios. Most of the galaxies are caught in the compaction phase, when gas cools and falls into galaxy centre, fuelling the dusty burst of star formation and the growing nucleus. We expect these DSFGs to be the high-z star-forming counterparts of massive quiescent galaxies. Some features of CO emission in three galaxies are suggestive of forthcoming/ongoing AGN feedback, which is thought to trigger the morphological transition from star-forming discs to early-type galaxies
Attenuation proxy hidden in surface brightness-colour diagrams. A new strategy for the LSST era
Large future sky surveys, such as the LSST, will provide optical photometry
for billions of objects. This paper aims to construct a proxy for the far
ultraviolet attenuation (AFUVp) from the optical data alone, enabling the rapid
estimation of the star formation rate (SFR) for galaxies that lack UV or IR
data. To mimic LSST observations, we use the deep panchromatic optical coverage
of the SDSS Photometric Catalogue DR~12, complemented by the estimated physical
properties for the SDSS galaxies from the GALEX-SDSS-WISE Legacy Catalog
(GSWLC) and inclination information obtained from the SDSS DR7. We restricted
our sample to the 0.025-0.1 z-spec range and investigated relations among
surface brightness, colours, and dust attenuation in the far UV range for
star-forming galaxies obtained from the spectral energy distribution (SED).
{Dust attenuation is best correlated with (u-r) colour and the surface
brightness in the u band (). We provide a dust attenuation proxy
for galaxies on the star-forming main sequence, which can be used for the LSST
or any other type of broadband optical survey. The mean ratio between the
catalogue values of SFR and those estimated using optical-only SDSS data with
the AFUVp prior calculated as SFR=log(SFR_{\tiny{\mbox{this
work}}}/SFR) is found to be less than 0.1~dex, while
runs without priors result in an SFR overestimation larger than 0.3~dex. The
presence or absence of theAFUVp has a negligible influence on the stellar mass
estimation (with M in the range from 0 to dex).
Forthcoming deep optical observations of the LSST Deep Drilling Fields, which
also have multi-wavelength data, will enable one to calibrate the obtained
relation for higher redshift galaxies and, possibly, extend the study towards
other types of galaxies, such as early-type galaxies off the main sequence.Comment: 18 pages, accepted for publication in Astronomy and Astrophysic
(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. II. The spatial extent of the radio-emitting regions
Radio emission at centimetre wavelengths from highly star-forming galaxies, like submillimetre galaxies (SMGs), is dominated by synchrotron radiation arising from supernova activity. Hence, radio continuum imaging has the potential to determine the spatial extent of star formation in these types of galaxies. Using deep, high-resolution (1σ = 2.3 μJy beam-1; 0.75 arcsec) centimetre radio-continuum observations taken by the Karl G. Jansky Very Large Array (VLA)-COSMOS 3 GHz Large Project, we studied the radio-emitting sizes of a flux-limited sample of SMGs in the COSMOS field. The target SMGs were originally discovered in a 1.1 mm continuum survey carried out with the AzTEC bolometer, and followed up with higher resolution interferometric (sub)millimetre continuum observations. Of the 39 SMGs studied here, 3 GHz emission was detected towards 18 of them (~46 ± 11%) with signal-to-noise ratios in the range of S/N = 4.2-37.4. Towards four SMGs (AzTEC2, 5, 8, and 11), we detected two separate 3 GHz sources with projected separations of ~1''&dotbelow;5-6''&dotbelow;6, but they might be physically related in only one or two cases (AzTEC2 and 11). Using two-dimensional elliptical Gaussian fits, we derived a median deconvolved major axis FWHM size of 0''&dotbelow;54±0''&dotbelow;11 for our 18 SMGs detected at 3 GHz. For the 15 SMGs with known redshift we derived a median linear major axis FWHM of 4.2 ± 0.9 kpc. No clear correlation was found between the radio-emitting size and the 3 GHz or submm flux density, or the redshift of the SMG. However, there is a hint of larger radio sizes at z ~ 2.5-5 compared to lower redshifts. The sizes we derived are consistent with previous SMG sizes measured at 1.4 GHz and in mid-J CO emission, but significantly larger than those seen in the (sub)mm continuum emission (typically probing the rest-frame far-infrared with median FWHM sizes of only ~1.5-2.5 kpc). One possible scenario is that SMGs have i) an extended gas component with a low dust temperature, which can be traced by low- to mid-J CO line emission and radio continuum emission; and ii) a warmer, compact starburst region giving rise to the high-excitation line emission of CO, which could dominate the dust continuum size measurements. Because of the rapid cooling of cosmic-ray electrons in dense starburst galaxies (~104-105 yr), the more extended synchrotron radio-emitting size being a result of cosmic-ray diffusion seems unlikely. Instead, if SMGs are driven by galaxy mergers - a process where the galactic magnetic fields can be pulled out to larger spatial scales - the radio synchrotron emission might arise from more extended magnetised interstellar medium around the starburst region