arXiv subjects

Andrea Lapi

Publications and source records attributed to Andrea Lapi.

At least 55 records · Page 3Linked to original sources

arXiv2024

Constraining the Initial-Mass Function via Stellar Transients

The stellar initial-mass function (IMF) represents a fundamental quantity in astrophysics and cosmology, describing the mass distribution of stars from low to very-high masses. It is intimately linked to a wide variety of topics, including stellar and binary evolution, galaxy evolution, chemical enrichment, and cosmological reionization. Nonetheless, the IMF still remains highly uncertain. In this work, we aim at determining the IMF with a novel approach based on the observed rates of transients of stellar origin. We parametrize the IMF with a simple, but flexible, Larson shape, and insert it into a parametric model for the cosmic UV luminosity density, local stellar mass density, type Ia supernova (SN Ia), core-collapse supernova (CCSN), and long gamma-ray burst (LGRB) rates as function of redshift. We constrain our free parameters by matching the model predictions to a set of empirical determinations for the corresponding quantities, via a Bayesian Markov-Chain Monte Carlo method. Remarkably, we are able to provide an independent IMF determination, with characteristic mass $m_c=0.10^{+0.24}_{-0.08}\:M_{\odot}$, and high-mass slope $ξ=-2.53^{+0.24}_{-0.27}$, that is in accordance with the widely-used IMF parameterizations (e.g. Salpeter, Kroupa, Chabrier). Moreover, the adoption of an up-to-date recipe for the cosmic metallicity evolution, allows us to constrain the maximum metallicity of LGRB progenitors to $Z_{max}=0.12^{+0.29}_{-0.05}\:Z_{\odot}$. We also find what progenitor fraction actually leads to SN Ia or LGRB emission, put constraints on the CCSN and LGRB progenitor mass ranges, and test the IMF universality. These results show the potential of this kind of approach for studying the IMF, its putative evolution with galactic environment and cosmic history, and the properties of SN Ia, CCSN and LGRB progenitors, especially considering the wealth of data incoming in the future.

astro-ph.HE↗

arXiv2024

The cosmic rate of Pair-Instability Supernovae

Pair-instability supernovae (PISNe) have crucial implications for many astrophysical topics, including the search for very massive stars, the black hole mass spectrum, and galaxy chemical enrichment. To this end, we need to understand where PISNe are across cosmic time, and what are their favourable galactic environments. We present a new determination of the PISN rate as a function of redshift, obtained by combining up-to-date stellar evolution tracks from the PARSEC and FRANEC codes, with an up-to-date semi-empirical determination of the star formation rate and metallicity evolution of star-forming galaxies throughout cosmic history. We find the PISN rate to exhibit a huge dependence on the model assumptions, including the criterion to identify stars unstable to pair production, and the upper limit of the stellar initial mass function. Remarkably, the interplay between the maximum metallicity at which stars explode as PISNe, and the dispersion of the galaxy metallicity distribution, dominates the uncertainties, causing a $\sim$ seven-orders-of-magnitude PISN rate range. Furthermore, we show a comparison with the core-collapse supernova rate, and study the properties of the favourable PISN host galaxies. According to our results, the main contribution to the PISN rate comes from metallicities between $\sim 10^{-3}$ and $10^{-2}$, against the common assumption that views very-low-metallicity, Population III stars as exclusive or dominant PISN progenitors. The strong dependencies we find offer the opportunity to constrain stellar and galaxy evolution models based on possible future (or the lack of) PISN observations.

astro-ph.HE↗

arXiv2024

Semi-empirical Estimates of the Cosmic Planet Formation Rate

We devise and exploit a data-driven, semi-empirical framework of galaxy formation and evolution, coupling it to recipes for planet formation from stellar and planetary science, to compute the cosmic planet formation rate, and the properties of the planets' preferred host stellar and galactic environments. We also discuss how the rates and formation sites of planets are affected when considering their habitability, and when including possible threatening sources related to star formation and nuclear activity. Overall, we conservatively estimate a cumulative number of some $10^{20}$ Earth-like planets and around $10^{18}$ habitable Earths in our past lightcone. Finally, we find that a few $10^{17}$ are older than our own Earth, an occurrence which places a loose lower limit a few $10^{-18}$ to the odds for a habitable world to ever hosting a civilization in the observable Universe.

astro-ph.GA↗

arXiv2024

Semi-Empirical Approach to [CII] Line Intensity Mapping

The line intensity mapping technique involves measuring the cumulative emission from specific spectral lines emitted by galaxies and intergalactic gas. This method provides a way to study the matter distribution and the evolution of large-scale structures throughout the history of the Universe. However, modeling intensity mapping from ab-initio approaches can be challenging due to significant astrophysical uncertainties and noticeable degeneracies among astrophysical and cosmological parameters. To address these challenges, we develop a semi-empirical, data-driven framework for galaxy evolution, which features a minimal set of assumptions and parameters gauged on observations. By integrating this with stellar evolution and radiative transfer prescriptions for line emissions, we derive the cosmic [CII] intensity over an extended redshift range $0 \lesssim z \lesssim 10$. Our approach is quite general and can be easily applied to other key lines used in intensity mapping studies, such as [OIII] and the CO ladder. We then evaluate the detectability of the [CII] power spectra using current and forthcoming observational facilities. Our findings offer critical insights into the feasibility and potential contributions of intensity mapping for probing the large-scale structure of the Universe and understanding galaxy evolution.

astro-ph.GA↗

arXiv2024

A Relativistic Scalar Model for Fractional Interaction between Dark Matter and Gravity

In a series of recent papers we put forward a ``fractional gravity'' framework striking an intermediate course between a modified gravity theory and an exotic dark matter (DM) scenario, which envisages the DM component in virialized halos to feel a non-local interaction mediated by gravity. The remarkable success of this model in reproducing several aspects of DM phenomenology motivates us to look for a general relativistic extension. Specifically, we propose a theory, dubbed Relativistic Scalar Fractional Gravity or RSFG, in which the trace of the DM stress-energy tensor couples to the scalar curvature via a non-local operator constructed with a fractional power of the d'Alembertian. We derive the field equations starting from an action principle, and then we investigate their weak field limit, demonstrating that in the Newtonian approximation the fractional gravity setup of our previous works is recovered. We compute the first-order post-Newtonian parameter $γ$ and its relation with weak lensing, showing that although in RSFG the former deviates from its GR values of unity, the latter is unaffected. We also perform a standard scalar-vector-tensor-decomposition of RSFG in the weak field limit, to highlight that gravitational waves propagate at the speed of light, though also an additional scalar mode becomes dynamical. Finally, we derive the modified conservation laws of the DM stress energy tensor in RSFG, showing that a new non-local force emerges, and hence that the DM fluid deviates from the geodesic solutions of the field equations.

gr-qc↗

arXiv2024

The miniJPAS Survey: The radial distribution of star formation rates in faint X-ray active galactic nuclei

We study the impact of black hole nuclear activity on both the global and radial star formation rate (SFR) profiles in X-ray-selected active galactic nuclei (AGN) in the field of miniJPAS, the precursor of the much wider J-PAS project. Our sample includes 32 AGN with z < 0.3 detected via the XMM-Newton and Chandra surveys. For comparison, we assembled a control sample of 71 star-forming (SF) galaxies with similar magnitudes, sizes, and redshifts. To derive the global properties of both the AGN and the control SF sample, we used CIGALE to fit the spectral energy distributions derived from the 56 narrowband and 4 broadband filters from miniJPAS. We find that AGN tend to reside in more massive galaxies than their SF counterparts. After matching samples based on stellar mass and comparing their SFRs and specific SFRs (sSFRs), no significant differences appear. This suggests that the presence of AGN does not strongly influence overall star formation. However, when we used miniJPAS as an integral field unit (IFU) to dissect galaxies along their position angle, a different picture emerges. We find that AGN tend to be more centrally concentrated in mass with respect to SF galaxies. Moreover, we find a suppression of the sSFR up to 1Re and then an enhancement beyond 1Re , strongly contrasting with the decreasing radial profile of sSFRs in SF galaxies. This could point to an inside-out quenching of AGN host galaxies. These findings suggest that the reason we do not see differences on a global scale is because star formation is suppressed in the central regions and enhanced in the outer regions of AGN host galaxies. While limited in terms of sample size, this work highlights the potential of the upcoming J-PAS as a wide-field low-resolution IFU for thousands of nearby galaxies and AGN.

astro-ph.GA↗

arXiv2024

The resolved star formation law in NGC 7469 from JWST, ALMA and VLA

We investigate the star formation process within the central 3.3 kpc region of the nearby luminous infrared Seyfert NGC 7469, probing scales ranging from 88 to 330 pc. We combine JWST/MIRI imaging with the F770W filter, with CO(2-1) and the underlying 1.3 mm dust continuum data from ALMA, along with VLA radio continuum observations at 22 GHz. NGC 7469 hosts a starburst ring which dominates the overall star formation activity. We estimate a global star formation rate SFR $\sim 11.5$ $\rm M_{\odot}~yr^{-1}$ from the radio at 22 GHz, and a cold molecular gas mass M(H2) $\sim$ 6.4 $\times$ $\rm 10^9 M_{\odot}$ from the CO(2-1) emission. We find that the 1.3 mm map shows a morphology remarkably similar to those traced by the 22 GHz and the 7.7 $\rm μm$ polycyclic aromatic hydrocarbon (PAH) emission observed with JWST. The three tracers reproduce the morphology of the starburst ring with good agreement. We further investigate the correlations between the PAHs, the star formation rate and the cold molecular gas. We find a stronger correlation of the PAHs with the star formation than with the CO, with steeper correlations within the starburst ring ($n > 2$) than in the outer region ($n < 1$). We derive the correlation between the star formation rate and the cold molecular gas mass surface densities, the Kennicutt-Schmidt star formation law. Comparisons with other galaxy populations, including starburst galaxies and active galactic nuclei, highlighted that NGC 7469 exhibits an intermediate behavior to the Kennicutt-Schmidt relations found for these galaxy populations.

astro-ph.GA↗

arXiv2024

Unveiling the (in)consistencies among the galaxy stellar mass function, star formation histories, satellite abundances and intracluster light from a semi-empirical perspective

In a hierarchical, dark matter-dominated Universe, stellar mass functions (SMFs), galaxy merger rates, star formation histories (SFHs), satellite abundances, and intracluster light, should all be intimately connected observables. However, the systematics affecting observations still prevent universal and uniform measurements of, for example, the SMF and the SFHs, inevitably preventing theoretical models to compare with multiple data sets robustly and simultaneously. We here present our holistic semi-empirical model DECODE (Discrete statistical sEmi-empiriCal mODEl) that converts via abundance matching dark matter merger trees into galaxy assembly histories, using different SMFs in input and predicting all other observables in output in a fully data-driven and self-consistent fashion with minimal assumptions. We find that: 1) weakly evolving or nearly constant SMFs below the knee ($M_\star \lesssim 10^{11} \, M_\odot$) are the best suited to generate star formation histories aligned with those inferred from MaNGA, SDSS, GAMA, and, more recently, JWST; 2) the evolution of satellites after infall only affects the satellite abundances and star formation histories of massive central galaxies but not their merger histories; 3) the resulting SFR-$M_\star$ relation is lower in normalization by a factor of $\sim 2$ with respect to observations, with a flattening at high masses more pronounced in the presence of mergers; 4) the latest data on intracluster light can be reproduced if mass loss from mergers is included in the models. Our findings are pivotal in acting as pathfinder to test the self-consistency of the high-quality data from, e.g., JWST and Euclid.

astro-ph.GA↗

arXiv2024

Dark progenitors and massive descendants: A first ALMA perspective on Radio-Selected NIRdark galaxies in the COSMOS field

We present the first spectroscopic ALMA follow-up for a pilot sample of nine Radio-Selected NIRdark galaxies in the COSMOS field. These sources were initially selected as radio-detected sources (S(3GHz)>12.65 uJy), lacking an optical/NIR counterpart in the COSMOS2015 catalog (Ks>24.7 mag), with just three of them subsequently detected in the deeper COSMOS2020. Several studies highlighted how this selection could provide a population of highly dust-obscured, massive, and star-bursting galaxies. With these new ALMA observations, we assess the spectroscopic redshifts of this pilot sample of sources and improve the quality of the physical properties estimated through SED-fitting. Moreover, we measure the quantity of molecular gas present inside these galaxies and forecast their potential evolutionary path, finding that the RS-NIRdark galaxies could represent a likely population of high-z progenitors of the massive and passive galaxies discovered at z~3. Finally, we present some initial constraints on the kinematics of the ISM within the analyzed galaxies, reporting a high fraction (~55%) of double-peaked lines that can be interpreted as the signature of a rotating structure in our targets or with the presence of major mergers in our sample. Our results presented in this paper showcase the scientific potential of (sub)mm observations for this elusive population of galaxies and highlight the potential contribution of these sources in the evolution of the massive and passive galaxies at high-z.

astro-ph.GA↗

arXiv2024

Methodological refinement of the submillimeter galaxy magnification bias. I. Cosmological analysis with a single redshift bin

The main goal of this work, the second in a three-paper series, is to test the impact of a methodological improvement in measuring the magnification bias signal on a sample of submillimeter galaxies and its implications for constraining cosmological parameters. The analysis considers the angular cross-correlation function between a foreground sample of GAMA galaxies ($0.2<z<0.8$) and a background sample of H-ATLAS submillimeter galaxies ($1.2<z<4.0$). A refined methodology, discussed extensively in Paper I, is used. By interpreting the weak lensing signal within the halo model and employing an MCMC algorithm, the posterior distribution of the halo occupation distribution (HOD) and cosmological parameters is obtained for a flat $Λ$CDM model. The analysis incorporates the foreground angular auto-correlation function to account for galaxy clustering. The results demonstrate a remarkable improvement in uncertainties for both HOD and cosmological parameters compared to previous studies. However, when using the cross-correlation data alone, the estimation of $σ_8$ depends on prior knowledge of $β$, the logarithmic slope of the background number counts. Assuming a physically motivated prior distribution for $β$, mean values of $Ω_m=0.18^{+0.03}{-0.03}$ and $σ_8=1.04^{+0.11}{-0.07}$ are obtained. These results may however be subject to an inherent bias in the data due to anomalous behavior observed in the G15 field. After excluding the G15 region, the mean values shift to $Ω_m=0.30^{+0.05}{-0.06}$ and $σ_8=0.92^{+0.07}{-0.07}$. This becomes more apparent when adding the clustering of the foreground sample, but the dependence on $β$ information disappears, mitigating the aforementioned issue. Excluding the G15 region, the joint analysis yields mean values of $Ω_m=0.36^{+0.03}{-0.07}$, $σ_8=0.90^{+0.03}{-0.03}$, and $h=0.76^{+0.14}_{-0.14}$.

astro-ph.CO↗

arXiv2024

Ionised AGN outflows in the Goldfish galaxy -- The illuminating and interacting red quasar eFEDSJ091157.4+014327 at z $\sim$ 0.6

Evolutionary models suggest that the initial growth phases of active galactic nuclei (AGN) are dust-enshrouded, and characterised by jet/wind outflows that should gradually clear the interstellar medium (ISM) in the host by heating and/or expelling the surrounding gas. eFEDSJ091157.4$+$014327 (z$\sim$0.6) was selected from X-ray samples for its characteristics that are similar to sources with outflows which include red, obscured and X-ray luminous. We aim to explore the environment around this red quasar and characterise kinematics within the system. We used spatially resolved spectroscopic data from Multi Unit Spectroscopic Explorer (MUSE) with an average seeing of 0.6" to construct flux, velocity and velocity dispersions maps. We found that the quasar is embedded in an interacting and merging system with three other galaxies $\sim$ 50 kpc from its nucleus. Spatially resolved kinematics reveal that the quasar has extended ionised outflows of up to 9.2 kpc with positive and negative velocities up to 1000 km s$^{-1}$ and -1200 km s$^{-1}$, respectively. The velocity dispersion (W$_{80}$) ranges from 600-1800 km s$^{-1}$. We associate the presence of turbulent and high-velocity components with the outflow. The total mass outflow rate is estimated to be $\sim$ 10 M$_{\odot}$ yr$^{-1}$ and kinetic power of 2x10$^{42}$ erg s$^{-1}$. The kinetic coupling efficiencies range from 0.01%-0.03% and the momentum boosts are $\sim$ 0.2. These low values indicate that the ionised outflow is not energetically relevant. These values don't align with the theoretical predictions of both radiation-pressure-driven outflows and energy-conserving mechanisms. However, note that our results are based only on the ionised phase while theoretical predictions are multiphase. Moreover, the mass loading factor of $\sim$ 5 is an indication that these outflows are more likely AGN-driven than star formation-driven.

astro-ph.GA↗

arXiv2024

Astrochemistry of the molecular gas in Dusty Star-Forming Galaxies at the Cosmic Noon

FIR and submm observations have established the fundamental role of dust-obscured star formation in the assembly of stellar mass over the past 12 billion years. At z between 2 and 4, the bulk of star formation is enshrouded in dust, and dusty star forming galaxies (DSFGs) contain about half of the total stellar mass density. Star formation develops in dense molecular clouds, and is regulated by a complex interplay between all the ISM components that contribute to the energy budget of a galaxy: gas, dust, cosmic rays, interstellar electromagnetic fields, gravitational field, dark matter. Molecular gas is the actual link between star forming gas and its complex environment, providing by far the richest amount of information about the star formation process. However, molecular lines interpretation requires complex modeling of astrochemical networks, which regulate the molecular formation and establishes molecular abundances in a cloud, and a modeling of the physical conditions of the gas in which molecular energy levels become populated. This paper critically reviews the main astrochemical parameters needed to get predictions about molecular signals in DSFGs. We review the current knowledge and the open questions about the interstellar medium of DSFGs, outlying the key role of molecular gas as a tracer and shaper of the star formation process.

astro-ph.GA↗

arXiv2024

Astrophysical and Cosmological Relevance of the High-Frequency Features in the Stochastic Gravitational-Wave Background

The stochastic gravitational-wave background (SGWB) produced by merging neutron stars exhibits a peak in the kHz band. In this paper, we develop a theoretical framework to exploit this distinctive feature through a Markov Chain Monte Carlo analysis using a simulated dataset of SGWB measurements within this frequency range. The aim is to use the SGWB peak as an observable to constrain a set of astrophysical and cosmological parameters that accurately describe the sources of the SGWB. We examine how variations in these parameters impact the morphology of the SGWB and investigate the necessary sensitivity to effectively constrain them. Given our priors on astrophysical and cosmological parameters, and assuming a power-law integrated sensitivity curve of the order of $10^{-11}$ between 1 kHz and 5 kHz, we show that the values of the chirp mass and common envelope efficiency of the binary systems are retrieved with percent accuracy. Furthermore, the method allows for the reconstruction of the cosmological expansion history populated by these binaries, encompassing the Hubble constant, matter abundance, and the effective equation of state of dark energy.

gr-qc↗

arXiv2024

Teaming-up radio and submm-FIR observations to probe dusty star-forming galaxies

In this paper, we investigate the benefits of teaming up data from the radio to the far- 1 infrared (FIR) regime for the characterization of Dusty Star-Forming Galaxies (DSFGs). These galaxies 2 are thought to be the star-forming progenitors of local massive quiescent galaxies, and play a pivotal 3 role in the reconstruction of the cosmic star formation rate density up to high redshift. Due to their 4 dust-enshrouded nature, DSFGs are often invisible in the near-infrared/Optical/UV bands. Therefore, 5 they necessitate observations at longer wavelengths, primarily the FIR, where dust emission occurs, 6 and radio, which is not affected by dust absorption. Combining data from these two spectral windows 7 makes it possible to characterize even the dustiest objects, enabling the retrieval of information about 8 their age, dust temperature, and star-formation status, and facilitates the differentiation between 9 various galaxy populations that evolve throughout cosmic history. Despite the detection of faint radio 10 sources being a challenging task, this study demonstrates that an effective strategy to build statistically 11 relevant samples of DSFGs would be reaching deep sensitivities in the radio band, even restricted to 12 smaller areas, and then combining these radio observations with FIR/submm data. Additionally, 13 the paper quantifies the improvement in the Spectral Energy Distribution (SED) reconstruction of 14 DSFGs by incorporating ALMA band measurements, in particular, in its upgraded status thanks to 15 the anticipated Wideband Sensitivity Upgrade.

astro-ph.GA↗

arXiv2024

Star Formation and Dust in the Cosmic Web

The large-scale environment of the cosmic web is believed to impact galaxy evolution, but there is still no consensus regarding the mechanisms. We use a semi-analytic model (SAM) galaxy catalog to study the star formation and dust content of local galaxies in different cosmic environments of the cosmic web, namely voids, filaments, walls, and nodes. We find a strong impact of the environment only for galaxies with $M_{\rm stars}\lesssim10^{10.8}\, M_\odot$: the less dense the environment, the larger the star formation rate and dust content at fixed stellar mass. This is attributed to the fact that galaxies in less dense environments typically feature younger stellar populations, a slower evolution of their stellar mass and a delayed star formation compared to galaxies in denser environments. As for galaxies with $M_{\rm stars}\gtrsim 10^{10.8}\, M_\odot$ differences among environments are milder due to the disc instability (DI) driven supermassive black hole (SMBH) growth implemented in the SAM, which makes SMBH growth, and thus galaxy quenching, environment insensitive. We qualitatively test our predictions against observations by identifying environments in the SDSS-DR16 using dust masses derived from the GAMA survey. The agreement is encouraging, particularly at ${\rm log} \, M_{\rm stars}/M_\odot\gtrsim 10.5-11$, where sSFRs and dust masses appear quite environment-insensitive. This result confirms the importance of in situ growth channels of SMBHs.

astro-ph.GA↗

arXiv2024

Scrutinising evidence for the triggering of Active Galactic Nuclei in the outskirts of massive galaxy clusters at $z\approx1$

Environmental effects are believed to play an important yet poorly understood role in triggering accretion events onto the supermassive black holes (SMBHs) of galaxies (Active Galactic Nuclei; AGN). Massive clusters, which represent the densest structures in the Universe, provide an excellent laboratory to isolate environmental effects and study their impact on black hole growth. In this work, we critically review observational evidence for the preferential activation of SMBHs in the outskirts of galaxy clusters. We develop a semi-empirical model under the assumption that the incidence of AGN in galaxies is independent of environment. We demonstrate that the model is broadly consistent with recent observations on the AGN halo occupation at $z=0.2$, although it may overpredict satellite AGN in massive halos at that low redshift. We then use this model to interpret the projected radial distribution of X-ray sources around high redshift ($z\approx1$) massive ($>5 \times 10^{14} \, M_\odot$) clusters, which show excess counts outside their virial radius. Such an excess naturally arises in our model as a result of sample variance. Up to 20% of the simulated projected radial distributions show excess counts similar to the observations, which are however, because of background/foreground AGN and hence, not physically associated with the cluster. Our analysis emphasises the importance of projection effects and shows that current observations of $z\approx1$ clusters remain inconclusive on the activation of SMBHs during infall.

astro-ph.GA↗

arXiv2024

Caustic and hydrostatic mass bias: Implications for modified gravity

We propose and perform a joint analysis of the two different mass estimates of galaxy clusters, namely the hydrostatic and caustic techniques. Firstly, we show comprehensively that the mass bias between these two techniques can be possibly alleviated when cluster-specific assumptions constrained using the hydrostatic technique are utilized within the caustic technique. While at face value this demotes the caustic technique from a completely independent method, this allows one to further tighten the constraints on the cluster mass and subsequently, allow us to test modifications to gravity. Implementing the aforementioned formalism for two well-observed massive galaxy clusters, A2029 and A2142, we highlight the proof of concept. In the current implementation, we use this method to constrain the Chameleon screening and Vainshtein screening. As anticipated, we show that the joint analysis can help improve the constraints on these modified gravity scenarios.

astro-ph.CO↗

arXiv2024

Observing Dusty Star-Forming Galaxies at the Cosmic Noon through Gravitational Lensing: Perspectives from New Generation Telescopes

Gravitational lensing, a compelling physical phenomenon, offers a unique avenue to investigate the morphology and physical properties of distant and faint celestial objects. This paper seeks to provide a comprehensive overview of the current state of observations concerning strongly lensed Dusty Star-Forming Galaxies. Emphasis is placed on the pivotal role played by cutting-edge facilities like the James Webb Space Telescope and the Square Kilometer Array Observatory. These advanced instruments, operating at disparate ends of the electromagnetic spectrum, in conjunction with the amplifying effect of gravitational lensing, promise significant steps in our understanding of these sources. The synergy between these observatories operating at two opposite ends of the spectrum, is poised to unlock crucial insights into the evolutionary path of high-redshift, dust-obscured systems and unravel the intricate interplay between Active Galactic Nuclei and their host galaxies.

astro-ph.GA↗