arXiv subjects

Hugo Martel

Publications and source records attributed to Hugo Martel.

At least 19 recordsLinked to original sources

arXiv2026

Unveiling a cosmic tango: Integral field spectroscopy and numerical simulations of Arp 143's interaction

We present spectral data cubes of the interacting galaxy system Arp 143, composed of the ring galaxy NGC 2445 and the lenticular galaxy NGC 2444, obtained with the imaging Fourier transform spectrometer SITELLE at the Canada-France-Hawaii Telescope. Our data allow to probe the kinematics of the interaction and the chemical properties of the ionized gas. Star-forming regions are almost exclusively found in the ring and nucleus of NGC 2445 with the exception of a few very faint ones discovered at the base of the long tidal plume extending north of NGC 2444. Analysis of the H{\alpha} velocity map reveals strong non-circular flows in the ring of NGC 2445, which is expanding. Its nucleus is off-centered with respect to the ring. Oxygen abundance in the ring is on average slightly sub-solar whereas it is close to solar in the nucleus. Broad-band images obtained with the Dragonfly Telephoto array allow to identify the tenuous stellar counterpart of the radio tidal plume. The interaction between the two galaxies is simulated with a chemodynamical evolution code; these simulations suggest that Arp 143 has resulted from a head-on collision between a S0 and a Sc spiral galaxy following a flyby encounter that triggered the formation of the long plume from debris of the disk galaxy.

astro-ph.GA↗

arXiv2026

Integral field spectroscopy and numerical simulations of the NGC 2207/IC 2163 system

We present integral field spectroscopy of the interacting galaxy system NGC 2207/IC 2163 obtained with the imaging Fourier Transform Spectrometer SITELLE. Approximately 1000 HII region complexes are detected in both galaxies and analyzed using their strong optical emission lines. Their properties were studied via BPT diagrams and their luminosity function. We conducted a detailed study of the distribution of oxygen abundance across the system using a series of strong-line O/H indicators and calibrations. Both galaxies exhibit negative galactocentric abundance gradients with a slope -0.015 dex kpc$^{-1}$. There are marginal signs of discontinuities in the O/H gradients with some indicators while no significant azimuthal variations are seen. A shallower slope in the HII region luminosity function between the arm and inter-arm regions in IC 2163 is observed, supporting previous conclusion that the star formation process in this galaxy eyelids has been altered during the interaction. The kinematics of the ionised gas reveal disturbed velocity fields, AGN-like features in the nucleus of NGC 2207, and elevated velocity dispersion in turbulent or feedback-driven regions. To interpret these findings, we modeled the collision using the numerical algorithm GCD+. The simulation reproduces key features of the system and demonstrates how close passages drive enhanced star formation and localized chemical enrichment. Finally, two dwarf galaxies in the field are found to have very similar systemic velocities as their larger counterparts, and could well play a minor role in the global interaction based on their morphology and position.

astro-ph.GA↗

arXiv2022

The interacting pair of galaxies Arp 82: Integral field spectroscopy and numerical simulations

Spectral data cubes of the interacting pair of galaxies NGC 2535 and NGC 2536 (the Arp 82 system) targeting bright emission lines in the visible band, obtained with the imaging Fourier transform spectrometer (iFTS) SITELLE attached to the Canada-France-Hawaii Telescope (CFHT), are presented. Analysis of H$\upalpha$ velocity maps reveals a bar in $\rm NGC\,2536$. In $\rm NGC\,2535$, we find strong non-circular motions outside the ocular ring, in the elliptical arc and tidal tails of $\rm NGC\,2535$ and a misalignment between the kinematic and photometric position angles. We detect 155 HII region complexes in the interacting pair of galaxies and determine oxygen abundances for 66 of them using different calibrators. We find, regardless of the indicator used, that the oxygen abundance distribution in $\rm NGC\,2536$ is shallow whereas, in $\rm NGC\,2535$, it is best fitted by two slopes, the break occurring beyond the ocular ring. The inner slope is comparable to the one observed in isolated normal star-forming galaxies but the outer slope is shallow. We present a numerical simulation of the interaction that reproduces the observed tidal features, kinematics, and metallicity distribution, to investigate the effect of the interaction on the galaxies. The model indicates that the galaxies have undergone a close encounter, strongly prograde for the primary, and are half way in their course to a second close encounter.

astro-ph.GA↗

arXiv2020

The Evolution of Magellanic-like Galaxy Pairs and The Production of Magellanic Stream Analogues in Simulations with Tides, Ram Pressure, and Stellar Feedback

We present a series of chemodynamical simulations of Magellanic-like systems consisting of two interacting, equal-mass dwarf galaxies orbiting a massive host galaxy, including feedback and star formation, tides, and ram pressure. We study the star formation and chemical enrichment history of the dwarfs, and the production of a Magellanic Stream analogue. The dwarfs interact with each other through tidal forces, distorting their morphologies and triggering star formation. A stream is naturally produced as outflows, induced by feedback and interactions, are stretched by tidal forces. Counter to some recent simulations, we find that the leading arm persists even in the presence of ram pressure from the host galaxy. Interactions between the dwarfs and the host galaxies produce multiple kinematic components in the stream, as observed. A combination of ongoing star-formation and entrained low-metallicity gas causes the stream to have a complex chemical structure, with an average metallicity that is generally lower than that of the dwarfs.

astro-ph.GA↗

arXiv2019

Clocking the formation of today's largest galaxies: Wide field integral spectroscopy of Brightest Cluster Galaxies and their surroundings

The formation and evolution of local brightest cluster galaxies (BCGs) is investigated by determining the stellar populations and dynamics from the galaxy core, though the outskirts and into the intracluster light (ICL). Integral spectroscopy of 23 BCGs observed out to 4 r_e is collected and high signal-to-noise regions are identified. Stellar population synthesis codes are used to determine the age, metallicity, velocity, and velocity dispersion of stars within each region. The intracluster light (ICL) spectra are best modeled with populations that are younger and less metal-rich than those of the BCG cores. The average BCG core age of the sample is 13.3$\pm$ 2.8 Gyr and the average metallicity is [Fe/H] = 0.30 $\pm$ 0.09, whereas for the ICL the average age is 9.2$\pm$3.5 Gyr and the average metallicity is [Fe/H] = 0.18$\pm$0.16. The velocity dispersion profile is seen to be rising or flat in most of the sample (17/23), and those with rising values reach the value of the host cluster's velocity dispersion in several cases. The most extended BCGs are closest to the peak of the cluster's X-ray luminosity. The results are consistent with the idea that the BCG cores and inner regions formed quickly and long ago, with the outer regions and ICL forming more recently, and continuing to assemble through minor merging. Any recent star formation in the BCGs is a minor component, and is associated with the cluster cool core status.

astro-ph.GA↗

arXiv2018

Chemodynamics of dwarf galaxies under ram-pressure

By implementing a dynamic wind-tunnel model in a smoothed-particle chemodynamic/hydrodynamic simulation suite, we have investigated the effects of ram pressure and tidal forces on dwarf galaxies similar to the Magellanic Clouds, within host galaxies with gas and dark matter halos that are varied, to compare the relative effects of tides and ram pressure. We concentrate on how the distributions of metals are affected by interactions. We find that while ram pressure and tidal forces have some effect on dwarf galaxy outflows, these effects do not produce large differences in the metal distributions of the dwarf disks other than truncation in the outer regions in some cases, and that confinement from the host galaxy gas halo appears to be more significant than ram pressure stripping. We find that stochastic variations in the star formation rate can explain the remaining variations in disk metal properties. This raises questions on the cause of low metallicities in dwarf galaxies.

astro-ph.GA↗

arXiv2018

Chemical enrichment in isolated barred spiral galaxies

To investigate the role of bars in the chemical evolution of isolated disc galaxies, we performed a series of 39 gas dynamical simulations of isolated barred and unbarred galaxies with various masses, initial gas fractions, and AGN feedback models. The presence of a bar drives a substantial amount of gas toward the central region of the galaxy. In the most massive galaxies, this results in a violent starburst, followed by a drop in star formation resulting from gas exhaustion. The time delay between Type Ia and Type II supernovae explosions means that barred galaxies experience a rapid increase in [O/H] in the central region, and a much more gradual increase in [Fe/H]. In unbarred galaxies, star formation proceeds at a slow and steady rate, and oxygen and iron are produced at steady rates which are similar except for a time offset. Comparing the abundance ratios in barred and unbarred galaxies with the same central stellar mass $M_*$, we find in barred galaxies an enhancement of 0.07 dex in [O/H], 0.05 dex in [Fe/H], and 0.05 dex in [O/Fe]. The [O/H] enhancement is in excellent agreement with observations from the SDSS. The initial gas fraction has very little effect on the abundance ratios in barred and unbarred galaxies, unless the galaxies experience a starburst. We considered AGN-host galaxies located near the bottom of the AGN regime, $M_*>3\times10^{10}M_\odot$, where AGN feedback dominates over supernovae feedback. We found that the impact of AGN feedback on the central abundances is marginal.

astro-ph.GA↗

arXiv2017

Star Formation History in Barred Spiral Galaxies. AGN Feedback

We present a numerical study of the impact of AGN accretion and feedback on the star formation history of barred disc galaxies. Our goal is to determine whether the effect of feedback is positive (enhanced star formation) or negative (quenched star formation), and to what extent. We performed a series of 12 hydrodynamical simulations of disc galaxies, 10 barred and 2 unbarred, with various initial gas fractions and AGN feedback prescriptions. In barred galaxies, gas is driven toward the centre of the galaxy and causes a starburst, followed by a slow decay, while in unbarred galaxies the SFR increases slowly and steadily. AGN feedback suppresses star formation near the central black hole. Gas is pushed away from the black hole, and collides head-on with inflowing gas, forming a dense ring at a finite radius where star formation is enhanced. We conclude that both negative and positive feedback are present, and these effects mostly cancel out. There is no net quenching or enhancement in star formation, but rather a displacement of the star formation sites to larger radii. In unbarred galaxies, where the density of the central gas is lower, quenching of star formation near the black hole is more efficient, and enhancement of star formation at larger radii is less efficient. As a result, negative feedback dominates. Lowering the gas fraction reduces the star formation rate at all radii, whether or not there is a bar or an AGN.

astro-ph.GA↗

arXiv2016

The Mass Dependence of Star Formation Histories in Barred Spiral Galaxies

We performed a series of 29 gasdynamical simulations of disc galaxies, barred and unbarred, with various stellar masses, to study the impact of the bar on star formation history. Unbarred galaxies evolve very smoothly, with a star formation rate (SFR) that varies by at most a factor of three over a period of 2 Gyr. The evolution of barred galaxies is much more irregular, especially at high stellar masses. In these galaxies, the bar drives a substantial amount of gas toward the centre, resulting in a high SFR, and producing a starburst in the most massive galaxies. Most of the gas is converted into stars, and gas exhaustion leads to a rapid drop of star formation after the starburst. In massive barred galaxies (stellar mass M* > 2x10^10 Msun) the large amount of gas funnelled toward the centre is completely consumed by the starburst, while in lower-mass barred galaxies it is only partially consumed. Gas concentration is thus higher in lower-mass barred galaxies than it is in higher-mass ones. Even though unbarred galaxies funnelled less gas toward their centre, the lower SFR allows this gas to accumulate. At late times, the star formation efficiency is higher in barred galaxies than unbarred ones, enabling these galaxies to maintain a higher SFR with a smaller gas supply. Several properties, such as the global SFR, central SFR, or central gas concentration, vary monotonically with time for unbarred galaxies, but not for barred galaxies. Therefore one must be careful when comparing barred and unbarred galaxies that share one observational property, since these galaxies might be at very different stages of their respective evolution.

astro-ph.GA↗

arXiv2016

Chemodynamic evolution of dwarf galaxies in tidal fields

The mass-metallicity relation shows that the galaxies with the lowest mass have the lowest metallicities. As most dwarf galaxies are in group environments, interaction effects such as tides could contribute to this trend. We perform a series of smoothed particle hydrodynamics (SPH) simulations of dwarf galaxies in external tidal fields to examine the effects of tides on their metallicities and metallicity gradients. In our simulated galaxies, gravitational instabilities drive gas inwards and produce centralized star formation and a significant metallicity gradient. Strong tides can contribute to these instabilities, but their primary effect is to strip the outer low-metallicity gas, producing a truncated gas disk with a large metallicity. This suggests that the role of tides on the mass-metallicity relation is to move dwarf galaxies to higher metallicities.

astro-ph.GA↗

arXiv2016

Metal diffusion in smoothed particle hydrodynamics simulations of dwarf galaxies

We perform a series of smoothed particle hydrodynamics simulations of isolated dwarf galaxies to compare different metal mixing models. In particular, we examine the role of diffusion in the production of enriched outflows, and in determining the metallicity distributions of gas and stars. We investigate different diffusion strengths, by changing the pre-factor of the diffusion coefficient, by varying how the diffusion coefficient is calculated from the local velocity distribution, and by varying whether the speed of sound is included as a velocity term. Stronger diffusion produces a tighter [O/Fe]-[Fe/H] distribution in the gas, and cuts off the gas metallicity distribution function at lower metallicities. Diffusion suppresses the formation of low-metallicity stars, even with weak diffusion, and also strips metals from enriched outflows. This produces a remarkably tight correlation between "metal mass-loading" (mean metal outflow rate divided by mean metal production rate) and the strength of diffusion, even when the diffusion coefficient is calculated in different ways. The effectiveness of outflows at removing metals from dwarf galaxies and the metal distribution of the gas is thus dependent on the strength of diffusion. By contrast, we show that the metallicities of stars are not strongly dependent on the strength of diffusion, provided that some diffusion is present.

astro-ph.GA↗

arXiv2014

Major Cluster Mergers and the Location of the Brightest Cluster Galaxy

Using a large N-body cosmological simulation combined with a subgrid treatment of galaxy formation, we study the formation and evolution of the galaxy and cluster population in a comoving volume (100 Mpc)^3 in a LCDM universe. At z = 0, our computational volume contains 1788 clusters with mass M_cl > 1.1x10^12 Msun, including 18 massive clusters with M_cl > 10^14 Msun. It also contains 1 088 797 galaxies with mass M_gal > 2x10^9 Msun and luminosity L > 9.5x10^5 Lsun. For each cluster, we identified the brightest cluster galaxy (BCG). We then computed the fraction f_BNC of clusters in which the BCG is not the closest galaxy to the center of the cluster in projection, and the ratio Dv/s, where Dv is the difference in radial velocity between the BCG and the whole cluster, and s is the radial velocity dispersion of the cluster. f_BNC increases from 0.05 for low-mass clusters (M_cl ~ 10^12 Msun) to 0.5 for high-mass ones (M_cl > 10^14 Msun), with no dependence on cluster redshift. The values of Dv/s vary from 0 to 1.8. These results are consistent with previous observational studies, and indicate that the central galaxy paradigm, which states that the BCG should be at rest at the center of the cluster, is usually valid, but exceptions are too common to be ignored. Analysis of the merger trees for the 18 most massive clusters in the simulation reveals that 16 of these clusters have experienced major mergers in the past. These mergers leave each cluster in a non-equilibrium state, but eventually the cluster settles into an equilibrium configuration, unless it is disturbed by another major merger. We found evidence that these mergers are responsible for the off-center positions and peculiar velocities of some BCGs. Our results thus support the merging-group scenario, in which some clusters form by the merger of smaller groups in which the galaxies have already formed.

astro-ph.CO↗

arXiv2013

Investigating Bar Structure of Disc Galaxies via PRIMAL: A PaRtIcle-by-particle M2M ALgorithm

We have modified our particle-by-particle adaptation of the made-to-measure (M2M) method, with the aim of modelling the Galactic disc from upcoming Galactic stellar survey data. In our new particle-by-particle M2M algorithm, PRIMAL, the observables of the target system are compared with those of the model galaxy at the position of the target stars, i.e. particles. The mass of the model particles are adjusted to reproduce the observables of the target system, and the gravitational potential is automatically adjusted by the changing mass of the particles. This paper builds upon our previous work, introducing likelihood-based velocity constraints in PRIMAL. In this paper we apply PRIMAL to barred disc galaxies created by a N-body simulation in a known dark matter potential, with no error in the observables. This paper demonstrates that PRIMAL can recover the radial profiles of the surface density, velocity dispersion in the radial and perpendicular directions, and the rotational velocity of the target discs, along with the apparent bar structure and pattern speed of the bar, especially when the reference frame is adjusted so that the bar angle of the target galaxy is aligned to that of the model galaxy at every timestep.

astro-ph.GA↗

arXiv2013

The Connection between Star Formation and Metallicity Evolution in Barred Spiral Galaxies

We have performed a series of chemodynamical simulations of barred disc galaxies. Our goal is to determine the physical processes responsible for the increase in the central gas-phase metallicity and of the central SFR observed in SDSS. We define a 2kpc diameter central aperture to approximate the integrated spectroscopic fibre measurements from the SDSS. The chemical evolution observed within this central region depends critically upon the relative size of the bar and the aperture, which evolves strongly with time. At t~0.5Gyr, a strong bar forms, whose length is considerably longer than the 2kpc aperture. The stars and gas lose angular momentum and follow elongated orbits that cause an intense mixing of the gas between the central region and its surroundings. During the next 1.5Gyr, the orbits of the gas contract significantly until the entire gas bar is contained in the 2kpc aperture, resulting in a net flux of gas into the central region. During this period, the metallicity in the central region increases steadily, and this enrichment is dominated by metal-rich gas that is flowing into the central region. The main result of this work is therefore that the observed enrichment in the centres of barred galaxies is not dominated by in-situ enrichment by stars formed in the centre. Rather, star formation occurs along the full length of the bar, much of which occurs initially outside the 2kpc aperture. About 50% of the metals that end up in the central region originate from this extended bar-long star formation, but flow into the central region due to loss of angular momentum. We conclude that there is no direct connection between central SFR and central metallicity. The central metallicity does not originate exclusively from central stars. Instead, the global SFR (especially along the bar) and the large-scale flow of enriched gas play a major role.

astro-ph.CO↗

arXiv2012

Fragmentation and Evolution of Molecular Clouds. III: The Effect of Dust and Gas Energetics

Dust and gas energetics are incorporated into a cluster-scale simulation of star formation in order to study the effect of heating and cooling on the star formation process. We build on our previous work by calculating separately the dust and gas temperatures. The dust temperature is set by radiative equilibrium between heating by embedded stars and radiation from dust. The gas temperature is determined using an energy-rate balance algorithm which includes molecular cooling, dust-gas collisional energy transfer, and cosmic-ray ionization. The fragmentation proceeds roughly similarly to simulations in which the gas temperature is set to the dust temperature, but there are differences. The structure of regions around sink particles have properties similar to those of Class 0 objects, but the infall speeds and mass accretion rates were, on average, higher than those seen for regions forming only low-mass stars. The gas and dust temperature have complex distributions not well modeled by approximations that ignore the detailed thermal physics. There is no simple relationship between density and kinetic temperature. In particular, high density regions have a large range of temperatures, determined by their location relative to heating sources. The total luminosity underestimates the star formation rate at these early stages, before ionizing sources are included, by an order of magnitude. As predicted in our previous work, a larger number of intermediate mass objects form when improved thermal physics is included, but the resulting IMF still has too few low mass stars. However, if we consider recent evidence on core-to-star efficiencies, the match to the IMF is improved.

astro-ph.SR↗

arXiv2012

The Fate of Dwarf Galaxies in Clusters and the Origin of Intracluster Stars. II. Cosmological Simulations

We combine a N-body simulation algorithm with a subgrid treatment of galaxy formation, mergers, and tidal destruction, and an observed conditional luminosity function Phi(L|M), to study the origin and evolution of galactic and extragalactic light inside a cosmological volume of size (100 Mpc)^3, in a concordance LCDM model. This algorithm simulates the growth of large-scale structures and the formation of clusters, the evolution of the galaxy population in clusters, the destruction of galaxies by mergers and tides, and the evolution of the intracluster light. We find that destruction of galaxies by mergers dominates over destruction by tides by about an order of magnitude at all redshifts. However, tidal destruction is sufficient to produce intracluster light fractions f_ICL that are sufficiently high to match observations. The bulk of the intracluster light (60%) is provided by intermediate galaxies of total masses 10^11 Msun-10^12 Msun and stellar masses 6x10^8 Msun-3x10^10 Msun that were tidally destroyed by even more massive galaxies. The contribution of low-mass galaxies to the intracluster light is small and the contribution of dwarf galaxies is negligible, even though, by numbers, most galaxies that are tidally destroyed are dwarfs. Tracking clusters back in time, we find that their values of f_ICL tend to increase over time, but can experience sudden changes that are sometimes non-monotonic. These changes occur during major mergers involving clusters of comparable masses but very different intracluster luminosities. Most of the tidal destruction events take place in the central regions of clusters. As a result, the intracluster light is more centrally concentrated than the galactic light. Our results support tidal destruction of intermediate-mass galaxies as a plausible scenario for the origin of the intracluster light.

astro-ph.CO↗

arXiv2011

Galactic Outflows and Evolution of the Interstellar Medium

We present a model to self-consistently describe the joint evolution of starburst galaxies and the galactic wind resulting from this evolution. We combine the population synthesis code Starburst99 with a semi-analytical model of galactic outflows and a model for the distribution and abundances of chemical elements inside the outflows. Starting with a galaxy mass, formation redshift, and adopting a particular form for the star formation rate, we describe the evolution of the stellar populations in the galaxy, the evolution of the metallicity and chemical composition of the interstellar medium (ISM), the propagation of the galactic wind, and the metal-enrichment of the intergalactic medium (IGM). In this paper, we study the properties of the model, by varying the mass of the galaxy, the star formation rate, and the efficiency of star formation. Our main results are the following: (1) For a given star formation efficiency f*, a more extended period of active star formation tends to produce a galactic wind that reaches a larger extent. If f* is sufficiently large, the energy deposited by the stars completely expels the ISM. Eventually, the ISM is being replenished by mass loss from supernovae and stellar winds. (2) For galaxies with masses above 10^11 Msun, the material ejected in the IGM always falls back onto the galaxy. Hence lower-mass galaxies are the ones responsible for enriching the IGM. (3) Stellar winds play a minor role in the dynamical evolution of the galactic wind, because their energy input is small compared to supernovae. However, they contribute significantly to the chemical composition of the galactic wind. We conclude that the history of the ISM enrichment plays a determinant role in the chemical composition and extent of the galactic wind, and therefore its ability to enrich the IGM.

astro-ph.CO↗

arXiv2011

Numerical Simulations of Galactic Outflows and Evolution of the IGM

Galactic outflows play a major role in the evolution of galaxies and the intergalactic medium (IGM). The energy deposited into the interstellar medium by supernovae and active galactic nuclei can accelerate the gas past the escape velocity, and eject it into the IGM. This will affect the subsequent evolution of the galaxy, by reducing or eliminating star formation, and quenching the accretion of matter onto the central AGN. Galactic outflows is the main process by which energy and processed interstellar matter is transported into the IGM. This affects the subsequent formation of other galaxies. The energy carried by outflows can strip protogalactic halos of their gas, preventing galaxies from forming. Conversely, the metals carried by outflows can modify the composition and cooling rates of the gas in protogalactic halos, favoring the formation of galaxies. In this paper, I review the various techniques used to simulate galactic outflows and their impact on galaxy and IGM evolution.

astro-ph.CO↗