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Ivanio Puerari

Publications and source records attributed to Ivanio Puerari.

At least 19 recordsLinked to original sources
arXiv2023

The cluster initial mass function of the M82 disk Super Star Clusters

The presence of a population of a large number ($\sim$400) of almost coeval (100--300 Myr) super star clusters (SSCs) in the disk of M82 offers an opportunity to construct the Cluster Initial Mass Function (CIMF) from the observed present-day Cluster Mass Function (CMF). We carry out the dynamical and photometric evolution of the CMF assuming the clusters move in circular orbits under the gravitational potential of the host galaxy using the semi-analytical simulation code EMACSS. We explore power-law and log-normal functions for the CIMFs, and populate the clusters in the disk assuming uniform, power-law, and exponential radial distribution functions. We find that the observed CMF is best produced by a CIMF that is power-law in form with an index of 1.8, for a power-law radial distribution function. More importantly, we establish that the observed turn-over in the present-day CMF is the result of observational incompleteness rather than due to dynamically induced effects, or an intrinsically log-normal CIMF, as was proposed for the fossil starburst region B of this galaxy. Our simulations naturally reproduce the mass-radius relation observed for a sub-sample of M82 SSCs.

astro-ph.GA↗
arXiv2022

SDSS IV MaNGA: Bar pattern speed in Milky Way Analogue galaxies

Most secular effects produced by stellar bars strongly depend on the pattern speed. Unfortunately, it is also the most difficult observational parameter to estimate. In this work, we measured the bar pattern speed of 97 Milky-Way Analogue galaxies from the MaNGA survey using the Tremaine-Weinberg method. The sample was selected by constraining the stellar mass and morphological type. We improve our measurements by weighting three independent estimates of the disc position angle. To recover the disc rotation curve, we fit a kinematic model to the H$_α$ velocity maps correcting for the non-circular motions produced by the bar. The complete sample has a smooth distribution of the bar pattern speed ($Ω_{Bar}=28.14^{+12.30}_{-9.55}$ km s$^{-1}$ kpc $^{-1}$), corotation radius ($R_{CR} = 7.82^{+3.99}_{-2.96}$ kpc) and the rotation rate ($\mathcal{R} = 1.35^{+0.60}_{-0.40}$). We found two sets of correlations: (i) between the bar pattern speed, the bar length and the logarithmic stellar mass (ii) between the bar pattern speed, the disc circular velocity and the bar rotation rate. If we constrain our sample by inclination within $30 \degree < i < 60 \degree$ and relative orientation $20\degree<|PA_{disc}-PA_{bar} |<70\degree$, the correlations become stronger and the fraction of ultra-fast bars is reduced from 20\% to 10\% of the sample. This suggest that a significant fraction of ultra-fast bars in our sample could be associated to the geometric limitations of the TW-method. By further constraining the bar size and disc circular velocity, we obtain a sub-sample of 25 Milky-Way analogues galaxies with distributions $Ω_{Bar}=30.48^{+10.94}_{-6.57}$ km s$^{-1}$ kpc$^{-1}$, $R_{CR} = 6.77^{+2.32}_{-1.91}$ kpc and $\mathcal{R} = 1.45^{+0.57}_{-0.43}$, in good agreement with the current estimations for our Galaxy.

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arXiv2015

Determination of resonance locations in barred spiral galaxies using multiband photometry

In this paper, we apply a method identified by Puerari & Dottori (1997) to find the corotation radii (CR) in spiral galaxies. We apply our method to 57 galaxies, 17 of which have already have their CR locations determined using other methods. The method we adopted entails taking Fourier transforms along radial cuts in the u, g, r, i, and z wavebands and comparing the phase angles as a function of radius between them. The radius at which the phase angles cross indicates the location of the corotation radius. We then calculated the relative bar pattern speed, $\mathcal{R}$, and classified the bar as "fast", where $\mathcal{R} < 1.4$, slow, where $\mathcal{R} \geq 1.4$, or intermediate, where the errors on $\mathcal{R}$ are consistent with the bar being "slow" or "fast". For the 17 galaxies that had their CR locations previously measured, we found that our results were consistent with the values of $\mathcal{R}$ obtained by the computer simulations of Rautiainen, Salo & Laurikainen (2008). For the larger sample, our results indicate that 34 out of 57 galaxies (~60%) have fast bars. We discuss these results in the context of its implications for dark matter concentrations in disk galaxies. We also discuss these results in the context of different models for spiral structure in disk galaxies.

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arXiv2013

Spiral Structure Dynamics in Pure Stellar Disk Models

In order to understand the physical mechanism underlying non-steady stellar spiral arms in disk galaxies we performed a series of N-body simulations with 1.2 and 8 million particles. The initial conditions were chosen to follow Kuijken-Dubinski models. In this work we present the results of a sub-sample of our simulations in which we experiment with different disk central radial velocity dispersion and the disk scale height.

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arXiv2013

Reviewing the observational evidence against long-lived spiral arms in galaxies

We review Foyle et al. (2011) previous results, by applying a Fourier intensity phases method to a nine object sample of galaxies. It was found that two of the objects (NGC 628 and NGC 5194), with strong two-arm patterns, present positive evidence for long-lived spirals. Only one of the objects (NGC 3627) shows the contrary evidence. As determined by an analysis of resolved mass maps, the rest of the objects can not be included in the analysis because they belong to flocculent and multi-arm type of spiral arms, which are not described by density wave theory.

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arXiv2010

The Large Magellanic Cloud: A power spectral analysis of Spitzer images

We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud. The power spectra of the FIR emission show two different power laws. At larger scales (kpc) the slope is ~ -1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with a value ~ -2.9. The break occurs at a scale around 100-200 pc. We interpret this break as the scale height of the dust disk of the LMC. We perform high resolution simulations with and without stellar feedback. Our AMR hydrodynamic simulations of model galaxies using the LMC mass and rotation curve, confirm that they have similar two-component power-laws for projected density and that the break does indeed occur at the disk thickness. Power spectral analysis of velocities betrays a single power law for in-plane components. The vertical component of the velocity shows a flat behavior for large structures and a power law similar to the in-plane velocities at small scales. The motions are highly anisotropic at large scales, with in-plane velocities being much more important than vertical ones. In contrast, at small scales, the motions become more isotropic.

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arXiv2010

ISM properties in hydrodynamic galaxy simulations: Turbulence cascades, cloud formation, role of gravity and feedback

We study the properties of ISM substructure and turbulence in hydrodynamic (AMR) galaxy simulations with resolutions up to 0.8 pc and 5x10^3 Msun. We analyse the power spectrum of the density distribution, and various components of the velocity field. We show that the disk thickness is about the average Jeans scale length, and is mainly regulated by gravitational instabilities. From this scale of energy injection, a turbulence cascade towards small-scale is observed, with almost isotropic small-scale motions. On scales larger than the disk thickness, density waves are observed, but there is also a full range of substructures with chaotic and strongly non-isotropic gas velocity dispersions. The power spectrum of vorticity in an LMC-sized model suggests that an inverse cascade of turbulence might be present, although energy input over a wide range of scales in the coupled gaseous+stellar fluid could also explain this quasi-2D regime on scales larger than the disk scale height. Similar regimes of gas turbulence are also found in massive high-redshift disks with high gas fractions. Disk properties and ISM turbulence appear to be mainly regulated by gravitational processes, both on large scales and inside dense clouds. Star formation feedback is however essential to maintain the ISM in a steady state by balancing a systematic gas dissipation into dense and small clumps. Our galaxy simulations employ a thermal model based on a barotropic Equation of State (EoS) aimed at modelling the equilibrium of gas between various heating and cooling processes. Denser gas is typically colder in this approach, which is shown to correctly reproduce the density structures of a star-forming, turbulent, unstable and cloudy ISM down to scales of a few parsecs.

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arXiv2007

Variation of Galactic Bar Length with Amplitude and Density as Evidence for Bar Growth over a Hubble Time

K_s-band images of 20 barred galaxies show an increase in the peak amplitude of the normalized m=2 Fourier component with the R_25-normalized radius at this peak. This implies that longer bars have higher $m=2$ amplitudes. The long bars also correlate with an increased density in the central parts of the disks, as measured by the luminosity inside 0.25R_25 divided by the cube of this radius in kpc. Because denser galaxies evolve faster, these correlations suggest that bars grow in length and amplitude over a Hubble time with the fastest evolution occurring in the densest galaxies. All but three of the sample have early-type flat bars; there is no clear correlation between the correlated quantities and the Hubble type.

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arXiv2007

Keck spectroscopy and Spitzer Space Telescope analysis of the outer disk of the Triangulum Spiral Galaxy M33

In an earlier study of the spiral galaxy M33, we photometrically identified arcs or outer spiral arms of intermediate age (0.6 Gyr - 2 Gyr) carbon stars precisely at the commencement of the HI-warp. Stars in the arcs were unresolved, but were likely thermally-pulsing asymptotic giant branch carbon stars. Here we present Keck I spectroscopy of seven intrinsically bright and red target stars in the outer, northern arc in M33. The target stars have estimated visual magnitudes as faint as V \sim 25 mag. Absorption bands of CN are seen in all seven spectra reported here, confirming their carbon star status. In addition, we present Keck II spectra of a small area 0.5 degree away from the centre of M33; the target stars there are also identified as carbon stars. We also study the non-stellar PAH dust morphology of M33 secured using IRAC on board the Spitzer Space Telescope. The Spitzer 8 micron image attests to a change of spiral phase at the start of the HI warp. The Keck spectra confirm that carbon stars may safely be identified on the basis of their red J-K_s colours in the outer, low metallicity disk of M33. We propose that the enhanced number of carbon stars in the outer arms are an indicator of recent star formation, fueled by gas accretion from the HI-warp reservoir.

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arXiv2004

Dust penetrated arm classes: insight from rising and falling rotation curves

We present near-infrared K-band images of 15 galaxies. We have performed a Fourier analysis on the spiral structure of these galaxies in order to determine their pitch angles and dust-penetrated arm classes. We have also obtained rotation curve data for these galaxies and calculated their shear rates. We show that there is a correlation between pitch angle and shear rate and conclude that the main determinant of pitch angle is the mass distribution within the galaxy. This correlation provides a physical basis for the dust-penetrated classification scheme of Block & Puerari (1999).

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arXiv2003

Penetration at high-z of the Greenberg "yellow stuff": Eyes to the Future with NGST

Quantitative morphological dust-penetrated templates for galaxies in our Local Universe may also serve as excellent templates for galaxies at high-z, because of partial/total decouplings expected between gaseous and stellar disks. NGC 922 is an optical irregular, which bears a striking resemblance to objects such as HDF2-86 (z=0.749) in the HDF north (Block et al. 2001). Its gaseous and stellar disk fully decouples; its stellar disk even presents modulation of spiral arms, usually only found in grand design spiral galaxies such as M81. Spiral galaxies in our Local Universe appear to be open systems, that are still forming and accreting mass, doubling their disk masses every 10 billion years (Block et al. 2002; Bournaud & Combes 2002). Likewise, galaxies at high-z may also be open systems, accreting mass, but herein NGST will provide pivotal answers. In this paper, we simulate the appearance of spiral galaxies (2--5" in angular diameter) with a class 6m Next Generation Space Telescope (NGST) in their dust penetrated restframe K' (2.1um) regime at redshifts of 0.7 and 1.2. Pitch angles, robustly derived from their Fourier spectra, remain unchanged from the present to when the Universe was roughly one half its present age. Furthermore, a ubiquity of low m (m=1 or m=2) spiral wavelets or modes is maintained in restframe K' images at z=0.7 and z=1.2, fully consistent with K' morphologies for spiral galaxies at z~0 in our local Universe. This paper is dedicated to the memory of J. Mayo Greenberg, whose final research delved into dust at high-z. Nominations for the 2004 Greenberg lecture are invited.

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arXiv2002

Gravitational torques in spiral galaxies: gas accretion as a driving mechanism of galactic evolution

The distribution of gravitational torques and bar strengths in the local Universe is derived from a detailed study of 163 galaxies observed in the near-infrared. The results are compared with numerical models for spiral galaxy evolution. It is found that the observed distribution of torques can be accounted for only with external accretion of gas onto spiral disks. Accretion is responsible for bar renewal - after the dissolution of primordial bars - as well as the maintenance of spiral structures. Models of isolated, non-accreting galaxies are ruled out. Moderate accretion rates do not explain the observational results: it is shown that galactic disks should double their mass in less than the Hubble time. The best fit is obtained if spiral galaxies are open systems, still forming today by continuous gas accretion, doubling their mass every 10 billion years.

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arXiv2002

Unveiling the Kinematics and Dynamics of Ionized Gas in the Nearby Irregular Galaxy NGC 4449

A detailed kinematic analysis of ionized gas in the nearby irregular galaxy NGC 4449 is presented. Observations are conducted in the spectral lines of Halpha and [SII]. Our scanning Fabry--Perot interferometric observations are presented from both a global as well as a local perspective. We have analysed the global velocity field, the spatially extended diffuse gaseous component (DIG), the HII region populations, and, furthermore, have determined the rotation curve based on the heliocentric radial velocities of the global Halpha spatial distribution. Our results for NGC 4449 show that the optical velocity field has a decreasing value in radial velocity along the optical bar from NE to SW. The DIG component that permeates the entire galaxy was analysed (up to a limiting surface brightness of ~ 3.165x10^-5 ergs cm$^-2 s^-1 steradian^-1). We find that the diffuse gas component presents peculiar kinematical features such as abrupt velocity gradients and highly supersonic velocity dispersions (sigma~4 times the values of the nearest HII regions) but that its kinematical and dynamical influence is important on both global and local scales. The optical rotation curve of this nearby irregular shows that the NE sector rotates like a solid body (V_rot~40 km s^-1 at R=2 kpc). For the SW side, our results are not conclusive; the behavior of the gas at those locations is chaotic. We conclude that the origin of such complex kinematics and dynamics is undoubtedly related to the aftermath of an interaction experienced by this galaxy in the past (abridged).

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arXiv2002

A Fabry-Perot Study of the Scd I galaxy NGC 5457

We have analyzed Halpha Fabry-Perot interferograms of NGC 5457 (M101) in order to calculate the rotation curve. We have also isolated a sample of 263 HII regions and we determined for each one its radial velocity and velocity dispersion. The rotation curve agrees with previous determinations and the mass derived from it is 9.8E10 solar mass. The distribution of velocity dispersion values of the HII regions presents a normal behavior, with a mean value of 30 km/sec.

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arXiv2000

Color Correlations in (S+S) Binary Galaxies I. The Holmberg Effect

Relying on his photometry of galaxies, Holmberg (1958) found, more than 40 years ago, that the color indices of paired galaxies were closely correlated. Our deep broad-band BVRI CCD photometry of 45 (S+S) pairs from the Karachentsev (1972) catalogue (see Hernandez Toledo and Puerari, this volume), and additional (B-V) color information from the literature (50 extra (S+S) pairs), help us to confirm the effect. This "Holmberg Effect" has long been remained unverified and not explained yet.

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arXiv2000

Analysis of resonances in grand design spiral galaxies

We have searched for corotations (CR) in three Southern grand design spiral galaxies: NGC 1365, NGC 1566 and NGC 2997. We have also introduced a method of quantifying errors in the phase diagram used to detect CR. We established the m=2 pattern CR at 12.1 kpc, 9.4 kpc and 7 kpc, for NGC 1365, NGC 1566 and NGC 2997, respectively. By using published rotation curves, we could determine spiral pattern angular speeds of 25.0 km/sec/kpc, 12.2 km/sec/kpc and 17.6 km/sec/kpc, respectively. A three armed component has been detected in NGC 2997, with the CR placed at 8.7 kpc with a pattern angular speed Omega_{CR_3}=12.7 km/sec/kpc. An m=1 component was detected in NGC 1566. We warily locate the CR at 7.1 kpc, with a pattern angular speed Omega_{CR} approx. 16.6 km/sec/kpc. This pattern does not present ILR. Ages have been determined by studying the radial density profile of the m=2 Fourier components in g (newly formed stars) and i (perturbing SDW supported by the disk of old stars), aided by the global aspect of the real spiral pattern in comparison with numerical simulations. The pattern is approx. 1200 Myr old in NGC 1365, approx. 800 Myr old in NGC 1566 and younger than 80 Myr in NGC 2997.

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arXiv2000

The detection of spiral arm modulation in the stellar disk of an optically flocculent and an optically grand design galaxy

Two dimensional Fourier spectra of near-infrared images of galaxies provide a powerful diagnostic tool for the detection of spiral arm modulation in stellar disks. Spiral arm modulation may be understood in terms of interference patterns of outgoing and incoming density wave packets or modes. The brightness along a spiral arm will be increased where two wave crests meet and constructively interfere, but will be decreased where a wave crest and a wave trough destructively interfere. Spiral arm modulation has hitherto only been detected in grand design spirals (such as Messier 81). Spiral arm amplitude variations have the potential to become a powerful constraint for the study of galactic dynamics. We illustrate our method in two galaxies: NGC 4062 and NGC 5248. In both cases, we have detected trailing and leading m=2 waves with similar pitch angles. This suggests that the amplification mechanism is the WASER type II. In this mechanism, the bulge region reflects (rather than refracts) incoming waves with no change of pitch angle, but only a change of their sense of winding. The ratio between the amplitudes of the leading and the trailing waves is about 0.5 in both cases, wherein the higher amplitude is consistently assigned to the trailing (as opposed to leading) mode. The results are particularly significant because NGC 5248 is an optically grand design galaxy, whereas NGC 4062 is optically flocculent. NGC 4062 represents the very first detection of spiral arm modulation in the stellar disk of an optically flocculent galaxy.

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