Late-type Spiral Galaxies Research Articles

JVLA Observations of IC 342: Probing Star Formation in the Nucleus

Abstract IC 342 is a nearby, late-type spiral galaxy with a young nuclear star cluster surrounded by several giant molecular clouds. The IC 342 nuclear region is similar to the Milky Way and therefore provides an interesting comparison. We explore star formation in the nucleus using radio recombination line (RRL) and continuum emission at 5, 6.7, 33, and 35 GHz with the JVLA. These radio tracers are largely unaffected by dust and therefore sensitive to all of the thermal emission from the ionized gas produced by early-type stars. We resolve two components in the RRL and continuum emission within the nuclear region that lie east and west of the central star cluster. These components are associated both spatially and kinematically with two giant molecular clouds. We model these regions in two ways: a simple model consisting of uniform gas radiating in spontaneous emission, or as a collection of many compact H ii regions in non-local thermodynamic equilibrium. The multiple H ii region model provides a better fit to the data and predicts many dense ( ), compact ( pc) H ii regions. For the whole nuclear region as defined by RRL emission, we estimate a hydrogen-ionizing rate of , corresponding to the equivalent of ∼2000 O6 stars and a star formation rate of ∼0.15 M ⊙ yr−1. We detect radio continuum emission west of the southern mini molecular spiral arm, consistent with trailing spiral arms.

Implications for the Origin of Early-type Dwarf Galaxies: A Detailed Look at the Isolated Rotating Early-type Dwarf Galaxy LEDA 2108986 (CG 611), Ramifications for the Fundamental Plane’s Kinematic Scaling, and the Spin–Ellipticity Diagram

Abstract Selected from a sample of nine, isolated, dwarf early-type galaxies (ETGs) with the same range of kinematic properties as dwarf ETGs in clusters, we use LEDA 2108986 (CG 611) to address the nature versus nurture debate regarding the formation of dwarf ETGs. The presence of faint disk structures and rotation within some cluster dwarf ETGs has often been heralded as evidence that they were once late-type spiral or dwarf irregular galaxies prior to experiencing a cluster-induced transformation into an ETG. However, CG 611 also contains significant stellar rotation (≈20 km s−1) over its inner half-light radius ( kpc), and its stellar structure and kinematics resemble those of cluster ETGs. In addition to hosting a faint young nuclear spiral within a possible intermediate-scale stellar disk, CG 611 has accreted an intermediate-scale, counter-rotating gas disk. It is therefore apparent that dwarf ETGs can be built by accretion events, as opposed to disk-stripping scenarios. We go on to discuss how both dwarf and ordinary ETGs with intermediate-scale disks, whether under (de)construction or not, are not fully represented by the kinematic scaling , and we also introduce a modified spin–ellipticity diagram – with the potential to track galaxies with such disks.

The role of environment on the star formation history of disc galaxies

NGC\,2403, NGC\,300 and M33 are three nearby pure-disc galaxies with similar stellar mass in different environments, they are benchmarks for understanding late-type spiral galaxies in different environments. The chemical evolution and growth of their discs are investigated by using the simple chemical evolution model, in which their discs are assumed to originate and grow through the accretion of the primordial gas, and the gas outflow process is also taken into account. Through comparative study of the best-fitting model predicted star formation histories for them, we hope to derive a picture of the local environment on the evolution and star formation histories of galaxies and whether or not the isolated galaxies follow similar evolution history. Our results show that these three galaxies accumulated more than 50 percent of their stellar mass at $z\,<\,1$. It can be also found that the metallicity gradients in isolated spiral galaxies NGC\,2403 and NGC\,300 are similar and obviously steeper than that in M33, when the metallicity gradients are expressed in ${\rm dex}\,R_{\rm 25}^{-1}$. The similar metallicity gradients in NGC\,2403 and NGC\,300 indicate that they may experience similar chemical evolutionary histories. The principal epoch of star formation on the discs of NGC\,2403 and NGC\,300 is earlier than that on the disc of M33, and the mean age of stellar populations along the discs of both NGC\,2403 and NGC\,300 is older than that of M33. Our results indicates that the evolution and star formation history of a galaxy indeed depends on its local environment, at least for galaxies with stellar mass of $10^{9.2}\,\rm M_{\odot}\sim10^{9.7}\,\rm M_{\odot}$.

Galaxy And Mass Assembly (GAMA): Gas Fueling of Spiral Galaxies in the Local Universe. I. The Effect of the Group Environment on Star Formation in Spiral Galaxies

Abstract We quantify the effect of the galaxy group environment (for group masses of 1012.5–1014.0 M ⊙) on the current star formation rate (SFR) of a pure, morphologically selected sample of disk-dominated (i.e., late-type spiral) galaxies with redshift ≤0.13. The sample embraces a full representation of quiescent and star-forming disks with stellar mass M * ≥ 109.5 M ⊙. We focus on the effects on SFR of interactions between grouped galaxies and the putative intrahalo medium (IHM) of their host group dark matter halos, isolating these effects from those induced through galaxy–galaxy interactions, and utilizing a radiation transfer analysis to remove the inclination dependence of derived SFRs. The dependence of SFR on M * is controlled for by measuring offsets Δlog(ψ *) of grouped galaxies about a single power-law relation in specific SFR, , exhibited by non-grouped “field” galaxies in the sample. While a small minority of the group satellites are strongly quenched, the group centrals and a large majority of satellites exhibit levels of ψ * statistically indistinguishable from their field counterparts, for all M *, albeit with a higher scatter of 0.44 dex about the field reference relation (versus 0.27 dex for the field). Modeling the distributions in Δlog(ψ *), we find that (i) after infall into groups, disk-dominated galaxies continue to be characterized by a similar rapid cycling of gas into and out of their interstellar medium shown prior to infall, with inflows and outflows of ∼1.5–5 x SFR and ∼1–4 x SFR, respectively; and (ii) the independence of the continuity of these gas flow cycles on M * appears inconsistent with the required fueling being sourced from gas in the circumgalactic medium on scales of ∼100 kpc. Instead, our data favor ongoing fueling of satellites from the IHM of the host group halo on ∼Mpc scales, i.e., from gas not initially associated with the galaxies upon infall. Consequently, the color–density relation of the galaxy population as a whole would appear to be primarily due to a change in the mix of disk- and spheroid-dominated morphologies in the denser group environment compared to the field, rather than to a reduced propensity of the IHM in higher-mass structures to cool and accrete onto galaxies. We also suggest that the required substantial accretion of IHM gas by satellite disk-dominated galaxies will lead to a progressive reduction in the specific angular momentum of these systems, thereby representing an efficient secular mechanism to transform morphology from star-forming disk-dominated types to more passive spheroid-dominated types.

THE LOCAL BLACK HOLE MASS FUNCTION DERIVED FROM THE MBH–P AND THE MBH–n RELATIONS

ABSTRACT We present a determination of the supermassive black hole (SMBH) mass function for early- and late-type galaxies in the nearby universe (z &lt; 0.0057), established from a volume-limited sample consisting of a statistically complete collection of the brightest spiral galaxies in the southern hemisphere. The sample is defined by limiting luminosity (redshift-independent) distance, D L = 25.4 Mpc, and a limiting absolute B-band magnitude, . These limits define a sample of 140 spiral, 30 elliptical (E), and 38 lenticular (S0) galaxies. We established the Sérsic index distribution for early-type (E/S0) galaxies in our sample. Davis et al. established the pitch angle distribution for their sample, which is identical to our late-type (spiral) galaxy sample. We then used the pitch angle and the Sérsic index distributions in order to estimate the SMBH mass function for our volume-limited sample. The observational simplicity of our approach relies on the empirical relation between the mass of the central SMBH and the Sérsic index for an early-type galaxy or the logarithmic spiral-arm pitch angle for a spiral galaxy. Our SMBH mass function agrees well at the high-mass end with previous values in the literature. At the low-mass end, although inconsistencies exist in previous works that still need to be resolved, our work is more in line with expectations based on modeling of black hole evolution.

The inner mass distribution of late-type spiral galaxies fromSAURONstellar kinematic maps

We infer the central mass distributions within 0.4-1.2 disc scale lengths of 18 late-type spiral galaxies using two different dynamical modelling approaches - the Asymmetric Drift Correction (ADC) and axisymmetric Jeans Anisotropic Multi-gaussian expansion (JAM) model. ADC adopts a thin disc assumption, whereas JAM does a full line-of-sight velocity integration. We use stellar kinematics maps obtained with the integral-field spectrograph SAURON to derive the corresponding circular velocity curves from the two models. To find their best-fit values, we apply Markov Chain Monte Carlo (MCMC) method. ADC and JAM modelling approaches are consistent within 5% uncertainty when the ordered motions are significant comparable to the random motions, i.e, $\overline{v_{\phi}}/\sigma_R$ is locally greater than 1.5. Below this value, the ratio $v_\mathrm{c,JAM}/v_\mathrm{c,ADC}$ gradually increases with decreasing $\overline{v_{\phi}}/\sigma_R$, reaching $v_\mathrm{c,JAM}\approx 2 \times v_\mathrm{c,ADC}$. Such conditions indicate that the stellar masses of the galaxies in our sample are not confined to their disk planes and likely have a non-negligible contribution from their bulges and thick disks.

SUPERMASSIVE BLACK HOLES AND THEIR HOST SPHEROIDS. III. THE MBH–nsph CORRELATION

ABSTRACT The Sérsic R 1 / n model is the best approximation known to date for describing the light distribution of stellar spheroidal and disk components, with the Sérsic index n providing a direct measure of the central radial concentration of stars. The Sérsic index of a galaxy’s spheroidal component, n sph, has been shown to tightly correlate with the mass of the central supermassive black hole, M BH. The M BH – n sph correlation is also expected from other two well known scaling relations involving the spheroid luminosity, L sph: the L sph – n sph and the M BH – L sph . Obtaining an accurate estimate of the spheroid Sérsic index requires a careful modeling of a galaxy’s light distribution and some studies have failed to recover a statistically significant M BH – n sph correlation. With the aim of re-investigating the M BH – n sph and other black hole mass scaling relations, we performed a detailed (i.e., bulge, disks, bars, spiral arms, rings, halo, nucleus, etc.) decomposition of 66 galaxies, with directly measured black hole masses, that had been imaged at 3.6 μm with Spitzer. In this paper, the third of this series, we present an analysis of the L sph – n sph and M BH – n sph diagrams. While early-type (elliptical+lenticular) and late-type (spiral) galaxies split into two separate relations in the L sph – n sph and M BH – L sph diagrams, they reunite into a single M BH ∝ n sph 3.39 ± 0.15 sequence with relatively small intrinsic scatter ( ϵ ≃ 0.25 dex ). The black hole mass appears to be closely related to the spheroid central concentration of stars, which mirrors the inner gradient of the spheroid gravitational potential.

Understanding biases when fitting disk truncations

AbstractTruncations in the stellar population at the edges of disk galaxies are thought to be a common morphological feature (e.g., Erwin et al. 2005; and more recently Marino et al. 2016). In fact, using imaging data from the SDSS, Pohlen &amp; Trujillo (2006) showed that only ~ 10% of face-on to intermediate inclined, nearby, late-type (Sb-Sdm) spiral galaxies have a normal/standard purely exponential disk down to the noise limit. In situations like these, the simultaneous fit of two lines, joined or not at an intermediate point (the break radius), constitutes a natural step towards the modelling of radial variation in surface brightness, metallicity, or any other relevant parameter. This work shows the results of simple simulations in which the simultaneous fit to two joined lines is compared to the simultaneous fit of two independent lines (i.e., two lines that do not necessarily coincide at an intermediate point), and also to the traditional single ordinary least squares fit. These simulations reveal some biases that should be taken into account when facing these kind of fitting procedures.

DETECTION OF MOLECULAR GAS IN VOID GALAXIES: IMPLICATIONS FOR STAR FORMATION IN ISOLATED ENVIRONMENTS

We present the detection of molecular gas from galaxies located in nearby voids using the CO line emission as a tracer. The observations were done using the 45m Nobeyama Radio Telescope. Void galaxies lie in the most under dense parts of our universe and a significant fraction of them are gas rich, late type spiral galaxies. Although isolated, they have ongoing star formation but appear to be slowly evolving compared to galaxies in denser environments. Not much is known about their star formation properties or cold gas content. In this study we searched for molecular gas in five void galaxies. The galaxies were selected based on their relatively high IRAS fluxes or Ha line luminosities, both of which signify ongoing star formation. All five galaxies appear to be isolated and two lie within the Bootes void. We detected CO line emission from four of the five galaxies in our sample and the molecular gas masses lie between 10^8 to 10^9 Msolar. We did follow-up Ha imaging observations of three detected galaxies using the Himalayan Chandra Telescope and determined their star formation rates (SFRs). The SFR varies from 0.2 to 1 Msolar/yr, which is similar to that observed in local galaxies. Our study indicates that although void galaxies reside in under dense regions, their disks contain molecular gas and have star formation rates similar to galaxies in denser environments.

The abundance of satellites depends strongly on the morphology of the host galaxy

Using the spectroscopic catalogue of the Sloan Digital Survey Data Release 10, we have explored the abundance of satellites around a sample of 254 massive (10^11< M_star < 2 x 10^11 M_sun) local (z < 0.025) galaxies. We have divided our sample into four morphological groups (E, S0, Sa, Sb/c). We find that the number of satellites with M_star > 10^9 M_sun and R < 300 kpc depends drastically on the morphology of the central galaxy. The average number of satellites per galaxy host (N_Sat/N_Host) down to a mass ratio of 1:100 is 4.5 +/- 0.3 for E hosts, 2.6 +/- 0.2 for S0, 1.5 +/- 0.1 for Sa and 1.2 +/- 0.2 for Sb/c. The amount of stellar mass enclosed by the satellites around massive E-type galaxies is a factor of 2, 4 and 5 larger than the mass in the satellites of S0, Sa and Sb/c types, respectively. If these satellites would eventually infall into the host galaxies, for all the morphological types, the merger channel will be largely dominated by satellites with a mass ratio satellite-host $\mu$ > 0.1. The fact that massive elliptical galaxies have a significant larger number of satellites than massive spirals could point out that elliptical galaxies inhabit heavier dark matter haloes than equally massive galaxies with later morphological types. If this hypothesis is correct, the dark matter haloes of late-type spiral galaxies are a factor ~2-3 more efficient on producing galaxies with the same stellar mass than those dark matter haloes of early-type galaxies.

A LUMINOUS X-RAY FLARE FROM THE NUCLEUS OF THE DORMANT BULGELESS SPIRAL GALAXY NGC 247

NGC 247 is a nearby late-type bulgeless spiral galaxy that contains an inactive nucleus. We report a serendipitous discovery of an X-ray flare from the galaxy center with a luminosity up to 2*10^39 erg/s in the 0.3-10 keV band with XMM-Newton. A Chandra observation confirms that the new X-ray source is spatially coincident with the galaxy nucleus. The XMM-Newton data revealed a hard power-law spectrum with a spectral break near 3-4 keV, no pulsations on timescales longer than 150 ms, and a flat power spectrum consistent with Poisson noise from 1 mHz to nearly 10 Hz. Follow-up observations with Swift detected a second flux peak followed by a luminosity drop by factor of almost 20. The spectral and temporal behaviors of the nuclear source are well consistent with the scenario that the flare was due to an outburst of a low-mass X-ray binary that contains a stellar-mass black hole emitting near its Eddington limit at the peak. However, it cannot be ruled out that the sudden brightening in the nucleus was due to accretion onto a possible low-mass nuclear black hole, fed by a tidally disrupted star or a gas cloud; the MAXI observations limit the peak luminosity of the flare to less than ~10^43 erg/s, suggesting that it is either a low mass black hole or an inefficient tidal disruption event (TDE).

Formation of S0 galaxies through mergers

The CALIFA team has recently found that the stellar angular momentum and concentration of late-type spiral galaxies are incompatible with those of lenticular galaxies (S0s), concluding that fading alone cannot satisfactorily explain the evolution from spirals into S0s. Here we explore whether major mergers can provide an alternative way to transform spirals into S0s by analysing the spiral-spiral major mergers from the GalMer database that lead to realistic, relaxed S0-like galaxies. We find that the change in stellar angular momentum and concentration can explain the differences in the $\lambda_\mathrm{Re}$--$R_{90}/R_{50}$ plane found by the CALIFA team. Major mergers thus offer a feasible explanation for the transformation of spirals into S0s.

A double molecular disc in the triple-barred starburst galaxy NGC 6946: structure and stability

The late-type spiral galaxy NGC 6946 is a prime example of molecular gas dynamics driven by ‘bars within bars’. Here, we use data from the BIMA Survey of Nearby Galaxies and HERA CO-Line Extragalactic Survey to analyse the structure and stability of its molecular disc. Our radial profiles exhibit a clear transition at distance R ∼ 1 kpc from the galaxy centre. In particular, the surface density profile breaks at R ≈ 0.8 kpc and is well fitted by a double exponential distribution with scalelengths R1 ≈ 200 pc and R2 ≈ 3 kpc, while the 1D velocity dispersion σ decreases steeply in the central kpc and is approximately constant at larger radii. The fact that we derive and use the full radial profile of σ rather than a constant value is perhaps the most novel feature of our stability analysis. We show that the profile of the Q stability parameter traced by CO emission is remarkably flat and well above unity, while the characteristic instability wavelength exhibits clear signatures of the nuclear starburst and inner bar within bar. We also show that CO-dark molecular gas, stars and other factors can play a significant role in the stability scenario of NGC 6946. Our results provide strong evidence that gravitational instability, radial inflow and disc heating have driven the formation of the inner structures and the dynamics of molecular gas in the central kpc.

THE STRUCTURE OF NUCLEAR STAR CLUSTERS IN NEARBY LATE-TYPE SPIRAL GALAXIES FROMHUBBLE SPACE TELESCOPEWIDE FIELD CAMERA 3 IMAGING

We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters residing in late-type spiral galaxies, in seven bands that span the near-ultraviolet to the near-infrared. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties. For six of the ten clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population which is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer wavelengths, as well as a correlation between the axis ratios of the NCs and their host galaxies. These observations indicate that blue disks aligned with the host galaxy plane are a common feature of nuclear clusters in late-type galaxies, but are difficult to detect in galaxies that are close to face-on. In color-color diagrams spanning the near-UV through the near-IR, most of the clusters lie far from single-burst evolutionary tracks, showing evidence for multi-age populations. Most of the clusters have integrated colors consistent with a mix of an old population (> 1 Gyr) and a young population (~100-300 Myr). The wide wavelength coverage of our data provides a sensitivity to populations with a mix of ages that would not be possible to achieve with imaging in optical bands only.

BUILDING LATE-TYPE SPIRAL GALAXIES BY IN-SITU AND EX-SITU STAR FORMATION

We analyze the formation and evolution of the stellar components in "Eris", a 120 pc-resolution cosmological hydrodynamic simulation of a late-type spiral galaxy. The simulation includes the effects of a uniform UV background, a delayed-radiative-cooling scheme for supernova feedback, and a star formation recipe based on a high gas density threshold. It allows a detailed study of the relative contributions of "in-situ" (within the main host) and "ex-situ" (within satellite galaxies) star formation to each major Galactic component in a close Milky Way analog. We investigate these two star-formation channels as a function of galactocentric distance, along different lines of sight above and along the disk plane, and as a function of cosmic time. We find that: 1) approximately 70 percent of today's stars formed in-situ; 2) more than two thirds of the ex-situ stars formed within satellites after infall; 3) the majority of ex-situ stars are found today in the disk and in the bulge; 4) the stellar halo is dominated by ex-situ stars, whereas in-situ stars dominate the mass profile at distances < 5 kpc from the center at high latitudes; and 5) approximately 25% of the inner, r < 20 kpc, halo is composed of in-situ stars that have been displaced from their original birth sites during Eris' early assembly history.

AGN III—primordial activity in the nuclei of disk galaxies with pseudobulges

Observational data on the evolution of quasars and galaxies of various morphological types and numerical simulations carried out by various groups are used to argue that low-redshift (z < 0.5) quasars of types I and II, identified with massive elliptical and spiral galaxies with classical bulges, cannot be undergoing a single, late phase of activity; i.e., their activity cannot be “primordial,” and must have “flared up” at multiple times in the past. This means that their appearance at low z is associated with recurrence of their activity—i.e., with major mergers of gas-rich galaxies (so-called wet major mergers)—since their lifetimes in the active phase do not exceed a few times 107 yrs. Only objects we have referred to earlier as AGN III, which are associated with the nuclei of isolated, late-type spiral galaxies with low-mass, rapidly-rotating “pseudobulges,” could represent primordial AGNs at low z. The black holes in such galaxies have masses M BH < 107 M ⊙, and the peculiarities of their nuclear spectra suggest that they may have very high specific rotational angular momenta per unit mass. Type I narrow-line (widths less than 2000 km/s) Seyfert galaxies (NLSyIs) with pseudobulges and black-hole masses M BH < 107 M ⊙ may be characteristic representatives of the AGN III population. Since NLSyI galaxies have pseudobulges while Type I broad-line Seyfert galaxies have classical bulges, these two types of galaxies cannot represent different evolutionary stages of a single type of object. It is possible that the precursors of NLSyIs are “Population A” quasars.

Luminosity-dependent star formation history of S0 galaxies: evidence from GALEX–SDSS–2MASS–WISE colours

We combine UV/optical/near-IR/mid-IR data on a sample of ∼240 S0 galaxies to examine various star formation related processes in them. We split the sample into bright and faint S0 galaxies based on their K-band luminosity. Comparing the far-ultraviolet (FUV)−near-ultraviolet (NUV) versus NUV−K colour–colour diagram with a simple stellar population model shows that ellipticals and bright S0 galaxies are dominated by a stellar population of age >109 yr while faint S0 galaxies may contain stars as young as 108 yr, providing evidence for relatively recent star formation activity. The strength of the 4000 Å break is also systematically higher in brighter S0 galaxies, again indicating the presence of an old stellar population. Their mid-IR colours indicate that bright S0 colours are like those of ellipticals while faint S0 colours are more like spirals. All these observations are consistent with a scenario in which low-luminosity S0 galaxies likely formed by the stripping of gas from the discs of late-type spiral galaxies, which in turn formed their pseudo-bulges through secular evolution processes, possibly involving multiple episodes of star formation. On the other hand, more luminous S0 galaxies likely formed the bulk of their stars at early epochs, similar to the star formation in elliptical galaxies, and are characterized by an old coeval stellar population and classical bulges.

Giant Low Surface Brightness Galaxies: Evolution in Isolation

Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in surface brightness. They often have bright bulges that are similar to those found in early type galaxies. The bulges can host low luminosity Active Galactic Nuclei (AGN) that have relatively low mass black holes. GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies. In fact many GLSB galaxies are found under dense regions close to the edges of voids. These galaxies have very massive dark matter halos that also contribute to their stability and lack of evolution. In this paper we briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive dark matter halos have led to the low star formation rates and the slower rate of evolution in these galaxies.

THE NOVA RATE IN NGC 2403

A multi-epoch H-alpha survey of the late-type spiral galaxy NGC 2403 has been completed in order to determine its nova rate. A total of 9 nova candidates were discovered in 48 nights of observation with two different telescopes over the period from February 2001 to April 2012. After making corrections for temporal coverage and spatial completeness, a nova rate of 2.0 (+0.5,-0.3) per year was determined. This rate corresponds to a luminosity-specific nova rate of 2.5+/-0.7 novae per year per 10^{10} solar luminosities in K. This value is consistent with that of the similar Hubble type galaxy, M33, and is typical of those of other galaxies with measured nova rates, which range from 1-3 novae per year per 10^{10} solar luminosities in K.

HOT DIFFUSE EMISSION IN THE NUCLEAR STARBURST REGION OF NGC 2903

(Abridged) We present a deep Chandra observation of the late-type barred spiral galaxy NGC 2903. The Chandra data reveal soft (kT_e ~ 0.2-0.5keV) diffuse emission in the nuclear starburst region and extending ~5kpc to the north and west of the nucleus. Much of this soft hot gas is likely to be from local active star-forming regions; however, besides the nuclear region, the morphology of hot gas does not strongly correlate with sites of active star formation. The central ~650 pc radius starburst zone exhibits much higher surface brightness diffuse emission than the surrounding regions and a harder spectral component in addition to its soft component. We interpret the hard component as being of thermal origin with kT_e~3.6keV and to be directly associated with a wind fluid produced by supernovae and massive star winds. The inferred terminal velocity for this hard component, ~1100 km/s, exceeds the local galaxy escape velocity suggesting a potential outflow. The softer extended emission does not display an obvious outflow geometry. However, the column density through which the X-rays are transmitted is lower to the west of the nucleus compared to the east and the surface brightness is higher there suggesting some soft hot gas originates from above the disk; viewed directly from the western zone but through the intervening galaxy disk from the eastern zone. There are several point-like sources in the nuclear region with X-ray spectra typical of compact binaries. None of these are coincident with the mass center of the galaxy and we place an upper limit luminosity from any point-like nuclear source to be < 2x10^38 ergs/s in the 0.5-8.0keV band which indicates that NGC 2903 lacks an active galactic nucleus. Heating from the nuclear starburst and a galactic wind may be responsible for preventing cold gas from accreting onto the galactic center.