The survival of dust grains in galaxies depends on various processes. Dust can be produced in stars, it can grow in the interstellar medium and be destroyed by astration and interstellar shocks. In ...this paper, we assemble a few data samples of local and distant star-forming galaxies to analyse various dust-related quantities in low- and high-redshift galaxies, and to study how the relations linking the dust mass to the stellar mass and star formation rate evolve with redshift. We interpret the available data by means of chemical evolution models for discs and proto-spheroid (PSPH) starburst galaxies. In particular, we focus on the dust-to-stellar mass (DTS) ratio, as this quantity represents a true measure of how much dust per unit stellar mass survives the various destruction processes in galaxies and is observable. The theoretical models outline the strong dependence of this quantity on the underlying star formation history. Spiral galaxies are characterized by a nearly constant DTS as a function of the stellar mass and cosmic time, whereas PSPHs present an early steep increase of the DTS, which stops at a maximal value and decreases in the latest stages. In their late starburst phase, these models show a decrease of the DTS with their mass, which allows us to explain the observed anti-correlation between the DTS and the stellar mass. The observed redshift evolution of the DTS ratio shows an increase from z ~ 0 to z ~ 1, followed by a roughly constant behaviour at ... Our models indicate a steep decrease of the global DTS at early times, which implies an expected decrease of the DTS at larger redshift. (ProQuest: ... denotes formulae/symbols omitted.)
The dust mass function from z ∼0 to z ∼2.5 Pozzi, F; Calura, F; Zamorani, G ...
Monthly notices of the Royal Astronomical Society,
02/2020, Letnik:
491, Številka:
4
Journal Article
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ABSTRACT
We derive for the first time the dust mass function (DMF) in a wide redshift range, from z ∼ 0.2 up to z ∼ 2.5. In order to trace the dust emission, we start from a far-IR (160-μm) Herschel ...selected catalogue in the COSMOS field. We estimate the dust masses by fitting the far-IR data (λrest$\,\, \buildrel\gt \over \sim \,\,$50 μm) with a modified black body function and we present a detailed analysis to take into account the incompleteness in dust masses from a far-IR perspective. By parametrizing the observed DMF with a Schechter function in the redshift range 0.1 < z ≤ 0.25, where we are able to sample faint dust masses, we measure a steep slope (α ∼1.48), as found by the majority of works in the Local Universe. We detect a strong dust mass evolution, with $M_{\rm d}^{\star }$ at z ∼ 2.5 almost 1 dex larger than in the local Universe, combined with a decrease in their number density. Integrating our DMFs, we estimate the dust mass density (DMD), finding a broad peak at z ∼ 1, with a decrease by a factor of ∼ 3 towards z ∼ 0 and z ∼ 2.5. In general, the trend found for the DMD mostly agrees with the derivation of Driver et al., another DMD determination based also on far-IR detections, and with other measures based on indirect tracers.
ABSTRACT
We study the impact of active galactic nuclei (AGNs) on the CO spectral line energy distribution (SLED) of high-z galaxies. In particular, we want to assess if the CO SLED can be used as a ...probe of AGN activity. To this purpose, we develop a semi-analytical model that takes into account the radiative transfer and the clumpy structure of giant molecular clouds where the CO lines are excited, their distribution in the galaxy disc, and the torus obscuration of the AGN radiation. We study the joint effect on the CO SLED excitation of (i) the X-ray luminosity from the AGNs (LX), (ii) the size of the molecular disc, (iii) the inclination angle (Ω) of the torus with respect to the molecular disc, and (iv) the Giant Molecular Cloud (GMC) mean density. We also discuss the possibility of an enhanced cosmic ray ionization rate (CRIR). We find that the X-ray-dominated region (XDR) generated by the AGNs in every case enhances the CO SLED for J > 5, with increasing excitation of high-J CO lines for increasing X-ray luminosity. Because high-z galaxies are compact, the XDR typically encloses the whole disc, thus its effect can be more important with respect to lower redshift objects. The impact of the XDR can be disentangled from an enhanced CRIR either if $L_\mathrm{ X}\,\gt\, 10^{44} \rm \, erg\, s^{-1}$, or if Ω ≥ 60°. We finally provide predictions on the CO(7–6)/C ii and CO(17–16)/C ii ratios as a function of LX, which can be relevant for ALMA follow-up of galaxies and quasars previously detected in C ii.
Abstract
We present ALMA observations at 107.291 GHz (band 3) and 214.532 GHz (band 6) of GMASS 0953, a star-forming galaxy at z = 2.226 hosting an obscured active galactic nucleus (AGN) that has ...been proposed as a progenitor of compact quiescent galaxies (QGs). We measure for the first time the size of the dust and molecular gas emission of GMASS 0953 that we find to be extremely compact (∼1 kpc). This result, coupled with a very high interstellar medium (ISM) density (n ∼ 105.5 cm−3), a low gas mass fraction (∼0.2), and a short gas depletion time-scale (∼150 Myr), implies that GMASS 0953 is experiencing an episode of intense star formation in its central region that will rapidly exhaust its gas reservoirs, likely aided by AGN-induced feedback, confirming its fate as a compact QG. Kinematic analysis of the CO(6–5) line shows evidence of rapidly rotating gas (Vrot = 320$^{+92}_{-53}$ km s−1), as observed also in a handful of similar sources at the same redshift. On-going quenching mechanisms could either destroy the rotation or leave it intact leading the galaxy to evolve into a rotating QG.
Aims.
We study the coevolution between the black hole accretion rate (BHAR) and the star formation rate (SFR) in different phases of galaxy life: main-sequence star-forming galaxies, quiescent ...galaxies, and starburst galaxies at different cosmic epochs.
Methods.
We exploited the unique combination of depth and area in the COSMOS field and took advantage of the X-ray data from the
Chandra
COSMOS-Legacy survey and the extensive multiwavelength ancillary data presented in the COSMOS2015 catalog, including in particular the UVista Ultra-deep observations. These large datasets allowed us to perform an X-ray stacking analysis and combine it with detected sources in a broad redshift interval (0.1 <
z
< 3.5) with unprecedented statistics for normal star-forming, quiescent, and starburst galaxies. The X-ray luminosity was used to predict the black holeAR, and a similar stacking analysis on far-infrared
Herschel
maps was used to measure the corresponding obscured SFR for statistical samples of sources in different redshifts and stellar mass bins.
Results.
We focus on the evolution of the average SFR-stellar mass (
M
*
) relation and compare it with the BHAR-
M
*
relation. This extends previous works that pointed toward the existence of almost linear correlations in both cases. We find that the ratio between BHAR and SFR does not evolve with redshift, although it depends on stellar mass. For the star-forming populations, this dependence on
M
*
has a logarithmic slope of ∼0.6 and for the starburst sample, the slope is ∼0.4. These slopes are both at odds with quiescent sources, where the dependence remains constant (log(BHAR/SFR) ∼ −3.4). By studying the specific BHAR and specific SFR, we find signs of downsizing for
M
*
and black hole mass (
M
BH
) in galaxies in all evolutionary phases. The increase in black hole mass-doubling timescale was particularly fast for quiescents, whose super-massive black holes grew at very early times, while accretion in star-forming and starburst galaxies continued until more recent times.
Conclusions.
Our results support the idea that the same physical processes feed and sustain star formation and black hole accretion in star-forming galaxies while the starburst phase plays a lesser role in driving the growth of the supermassive black holes, especially at high redshift. Our integrated estimates of the
M
*
−
M
BH
relation at all redshifts are consistent with independent determinations of the local
M
*
−
M
BH
relation for samples of active galactic nuclei. This adds key evidence that the evolution in the BHAR/SFR is weak and its normalization is relatively lower than that of local dynamical
M
*
−
M
BH
relations.
Abstract
We present a detailed analysis of the X-ray and molecular gas emission in the nearby galaxy NGC 34, to constrain the properties of molecular gas, and assess whether, and to what extent, the ...radiation produced by the accretion on to the central black hole affects the CO line emission. We analyse the CO spectral line energy distribution (SLED) as resulting mainly from Herschel and ALMA data, along with X-ray data from NuSTAR and XMM–Newton. The X-ray data analysis suggests the presence of a heavily obscured active galactic nucleus (AGN) with an intrinsic luminosity of L1–100 keV ≃ 4.0 × 1042 erg s−1. ALMA high-resolution data (θ ≃ 0.2 arcsec) allow us to scan the nuclear region down to a spatial scale of ≈100 pc for the CO(6–5) transition. We model the observed SLED using photodissociation region (PDR), X-ray-dominated region (XDR), and shock models, finding that a combination of a PDR and an XDR provides the best fit to the observations. The PDR component, characterized by gas density log(n/cm−3) = 2.5 and temperature T = 30 K, reproduces the low-J CO line luminosities. The XDR is instead characterized by a denser and warmer gas (log(n/cm−3) = 4.5, T = 65 K), and is necessary to fit the high-J transitions. The addition of a third component to account for the presence of shocks has been also tested but does not improve the fit of the CO SLED. We conclude that the AGN contribution is significant in heating the molecular gas in NGC 34.
The Atacama Large Millimeter Array (ALMA) Large Program to INvestigate CII at Early times (ALPINE) targets the CII 158
μ
m line and the far-infrared continuum in 118 spectroscopically confirmed ...star-forming galaxies between
z
= 4.4 and
z
= 5.9. It represents the first large CII statistical sample built in this redshift range. We present details regarding the data processing and the construction of the catalogs. We detected 23 of our targets in the continuum. To derive accurate infrared luminosities and obscured star formation rates (SFRs), we measured the conversion factor from the ALMA 158
μ
m rest-frame dust continuum luminosity to the total infrared luminosity (
L
IR
) after constraining the dust spectral energy distribution by stacking a photometric sample similar to ALPINE in ancillary single-dish far-infrared data. We found that our continuum detections have a median
L
IR
of 4.4 × 10
11
L
⊙
. We also detected 57 additional continuum sources in our ALMA pointings. They are at a lower redshift than the ALPINE targets, with a mean photometric redshift of 2.5 ± 0.2. We measured the 850
μ
m number counts between 0.35 and 3.5 mJy, thus improving the current interferometric constraints in this flux density range. We found a slope break in the number counts around 3 mJy with a shallower slope below this value. More than 40% of the cosmic infrared background is emitted by sources brighter than 0.35 mJy. Finally, we detected the CII line in 75 of our targets. Their median CII luminosity is 4.8 × 10
8
L
⊙
and their median full width at half maximum is 252 km s
−1
. After measuring the mean obscured SFR in various CII luminosity bins by stacking ALPINE continuum data, we find a good agreement between our data and the local and predicted SFR–
L
CII
relations.
We compare various star formation rate (SFR) indicators for star-forming galaxies at 1.4 < z < 2.5 in the COSMOS field. The main focus is on the SFRs from the far-IR (PACS-Herschel data) with those ...from the ultraviolet, for galaxies selected according to the BzK criterion. FIR-selected samples lead to a vastly different slope of the SFR–stellar mass (M
*) relation, compared to that of the dominant main-sequence population as measured from the UV, since the FIR selection picks predominantly only a minority of outliers. However, there is overall agreement between the main sequences derived with the two SFR indicators, when stacking on the PACS maps the BzK-selected galaxies. The resulting logarithmic slope of the SFR–M
* relation is ∼0.8–0.9, in agreement with that derived from the dust-corrected UV luminosity. Exploiting deeper 24 μm Spitzer data, we have characterized a subsample of galaxies with reddening and SFRs poorly constrained, as they are very faint in the B band. The combination of Herschel with Spitzer data has allowed us to largely break the age/reddening degeneracy for these intriguing sources, by distinguishing whether a galaxy is very red in B-z because of being heavily dust reddened, or whether because star formation has been (or is being) quenched. Finally, we have compared our SFR(UV) to the SFRs derived by stacking the radio data and to those derived from the Hα luminosity of a sample of star-forming galaxies at 1.4 < z < 1.7. The two sets of SFRs are broadly consistent as they are with the SFRs derived from the UV and by stacking the corresponding PACS data in various mass bins.
We study the relation of AGN accretion, star formation rate (SFR) and stellar mass (M
*) using a sample of ≈8600 star-forming galaxies up to z = 2.5 selected with Herschel imaging in the GOODS and ...COSMOS fields. For each of them we derive SFR and M
*, both corrected, when necessary, for emission from an active galactic nucleus (AGN), through the decomposition of their spectral energy distributions (SEDs). About 10 per cent of the sample are detected individually in Chandra observations of the fields. For the rest of the sample, we stack the X-ray maps to get average X-ray properties. After subtracting the X-ray luminosity expected from star formation and correcting for nuclear obscuration, we derive the average AGN accretion rate for both detected sources and stacks, as a function of M
*, SFR and redshift. The average accretion rate correlates with SFR and with M
*. The dependence on SFR becomes progressively more significant at z > 0.8. This may suggest that SFR is the original driver of these correlations. We find that average AGN accretion and star formation increase in a similar fashion with offset from the star-forming ‘main-sequence’. Our interpretation is that accretion on to the central black hole and star formation broadly trace each other, irrespective of whether the galaxy is evolving steadily on the main-sequence or bursting.
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