Dominant Galaxy Research Articles

ORIGIN AND EVOLUTION OF STRUCTURE FOR GALAXIES IN THE LOCAL GROUP

The Milky Way did not form in isolation, but is the product of a complex evolution of generations of mergers, collapses, star formation, supernovae and collisional heating, radiative and collisional cooling, and ejected nucleosynthesis. Moreover, all of this occurs in the context of the cosmic expansion, the formation of cosmic laments, dark-matter haloes, spiral density waves, and emerging dark energy. This paper summarizes a review of recent attempts to reconstruct this complex evolution. We compare simulated properties with various observed properties of the Local Group. Among the generic features of simulated systems is the tendency for galactic halos to form within the dark matter laments that dene a supergalactic plane. Gravitational interaction along this structure leads to a streaming ow toward the two dominant galaxies in the cluster. We analyze this alignment and streaming ow and compare with the observed properties of Local-Group galaxies. Our comparison with Local Group properties suggests that some dwarf galaxies in the Local Group are part of a local streaming ow. These simulations also suggest that a signicant fraction of the Galactic halo formed at large distances and arrived later along these streaming ows.

Characteristics of transonic spherical symmetric accretion flow in Schwarzschild-de Sitter and Schwarzschild anti-de Sitter backgrounds, in pseudo-general relativistic paradigm

In this paper, we present a complete work on steady state spherically symmetric Bondi type accretion flow in the presence of cosmological constant (Λ) in both Schwarzschild-de Sitter (SDS) and Schwarzschild anti-de Sitter (SADS) backgrounds considering an isolated supermassive black hole (SMBH), with the inclusion of a simple radiative transfer scheme, in the pseudo-general relativistic paradigm. We do an extensive analysis on the transonic behavior of the Bondi type accretion flow onto the cosmological BHs including a complete analysis of the global parameter space and the stability of flow, and do a complete study of the global family of solutions for a generic polytropic flow. Bondi type accretion flow in SADS background renders multiplicity in its transonic behavior with inner "saddle" type and outer "center" type sonic points, with the transonic solutions forming closed loops or contours. There is always a limiting value for ∣Λ∣ up to which we obtain valid stationary transonic solutions, which correspond to both SDS and SADS geometries; this limiting value moderately increases with the increasing radiative efficiency of the flow, especially correspond to Bondi type accretion flow in SADS background. Repulsive Λ suppresses the Bondi accretion rate by an order of magnitude for relativistic Bondi type accretion flow for a certain range in temperature, and with a marginal increase in the Bondi accretion rate if the corresponding accretion flow occurs in SADS background. However, for a strongly radiative Bondi type accretion flow with high mass accretion rate, the presence of cosmological constant do not much influence the corresponding Bondi accretion rate of the flow. Our analysis show that the relic cosmological constant has a substantial effect on Bondi type accretion flow onto isolated SMBHs and their transonic solutions beyond length-scale of kiloparsecs, especially if the Bondi type accretion occurs onto the host supergiant ellipticals or central dominant (CD) galaxies directly from ambient intercluster medium (ICM). However, for high mass accretion rate, the influence of cosmological constant on Bondi accretion dynamics, generically, diminishes. As active galactic nuclei (AGN)/ICM feedback can be advertently linked to Bondi type spherical accretion, any proper modeling of AGN feedback or megaparsecs-scale jet dynamics or accretion flow from ICM onto the central regions of host galaxies should take into account the relevant information of repulsive Λ, especially in context to supergiant elliptical galaxies or CD galaxies present in rich galaxy clusters. This could also explore the feasibility to limit the value of Λ, from the kinematics in local galactic-scales.

The Rotation of Galaxy Clusters

The method for detection of the galaxy cluster rotation based on the study of distribution of member galaxies with velocities lower and higher of the cluster mean velocity over the cluster image is proposed. The search for rotation is made for flat clusters with $a/b>1.8$ and BMI type clusters which are expected to be rotating. For comparison there were studied also round clusters and clusters of NBMI type, the second by brightness galaxy in which does not differ significantly from the cluster cD galaxy. Seventeen out of studied 65 clusters are found to be rotating. It was found that the detection rate is sufficiently high for flat clusters, over 60\%, and clusters of BMI type with dominant cD galaxy, ~ 35%. The obtained results show that clusters were formed from the huge primordial gas clouds and preserved the rotation of the primordial clouds, unless they did not have merging with other clusters and groups of galaxies, in the result of which the rotation has been prevented.

Companions around the nearest luminous galaxies: Segregation and selection effects

AbstractUsing the “Updated Nearby Galaxy Catalog”, we consider different properties of companion galaxies around luminous hosts in the Local Volume. The data on stellar masses, linear diameters, surface brightnesses, HI‐richness, specific star formation rate (sSFR), and morphological types are discussed for members of the nearest groups, including the Milky Way and M 31 groups, as a function of their separation from the hosts. Companion galaxies in groups tend to have lower stellar masses, smaller linear diameters, and fainter mean surface brightnesses as the distance to their host decreases. The hydrogen‐to‐stellar mass ratio of the companions increases with their linear projected separation from the dominant luminous galaxy. This tendency is more expressed around the bulge‐dominated hosts. While linear separation of the companions decreases, their mean sSFR becomes lower, accompanied with the increasing sSFR scatter. the typical linear projected separation of dSphs around the bulge‐dominated hosts, 350 kpc, is substantially larger than that around the disk‐dominated ones, 130 kpc. This difference probably indicates the presence of larger hot/warm gas haloes around the early‐type host galaxies. The mean fraction of dSph (quenched) companions in the 11 nearest groups as a function of their projected separation Rp can be expressed as ƒ(E) = (0.55–0.69)×Rp. The fraction of dSphs around the Milky Way and M 31 looks much higher than in other nearby groups because the quenching efficiency dramatically increases towards the ultra‐low mass companions. We emphasize that the observed properties of the Local Group are not typical for other groups in the Local Volume due to the role of selection effects caused by our location inside the Local Group. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Discovery of O vii line emitting gas in elliptical galaxies

In the cores of ellipticals, clusters, and groups of galaxies, the gas has a cooling time shorter than 1 Gyr. It is possible to probe cooling flows through the detection of Fe XVII and O VII emission lines, but so far O VII has not been detected in any individual object. The Reflection Grating Spectrometers (RGS) aboard XMM-Newton are currently the only instruments able to detect O VII in extended objects such as elliptical galaxies and galaxy clusters. We searched for evidence of O VII through all the archival RGS observations of galaxy clusters, groups of galaxies, and elliptical galaxies focusing on those with core temperatures below 1 keV. We have discovered O VII resonance (21.6A) and forbidden (22.1A) lines for the first time in the spectra of individual objects. O VII was detected at a level higher than three sigma in six elliptical galaxies: M 84, M 86, M 89, NGC 1316, NGC 4636, and NGC 5846. M 84, M 86 and M 89 are members of the Virgo Cluster, the others are central dominant galaxies of groups, and most them show evidence of O VI in UV spectra. We detect no significant trend between the Fe XVII and O VII resonance-to-forbidden line ratios, possibly because of the limited statistics. The observed line ratios <Fe(r/f), O(r/f)>= (0.52+/-0.02, 0.9+/-0.2) indicate that the spectra of all these ellipticals are affected by resonance scattering, suggesting low turbulence. Deeper exposures will help to understand whether the Fe XVII and O VII lines are both produced by the same cooling gas or by multiphase gas. Our O VII luminosities correspond to 0.2-2 Msun/yr, which agree with the predictions for ellipticals. Such weak cooling rates would not be detected in clusters because their spectra are dominated by the emission of hotter gas, and owing to their greater distance, the expected O VII line flux would be undetectable.

The GALEX Ultraviolet Virgo Cluster Survey (GUViCS)

We study the role of the environment on galaxy evolution using a sample of 868 galaxies in the Virgo cluster and in its surrounding regions selected from the GUViCS Survey with the purpose of understanding the origin of the red sequence in dense environments. We collected multifrequency data covering the whole electromagnetic spectrum for most of the galaxies. We identify the different dynamical substructures composing the Virgo cluster and we calculate the local density of galaxies using different methods. We then study the distribution of galaxies belonging to the red sequence, the green valley, and the blue cloud within the different cluster substructures. Our analysis indicates that all the most massive galaxies are slow rotators and are the dominant galaxies of the different cluster substructures generally associated with a diffuse X-ray emission. They are probably the result of major merging events that occurred at early epochs. Slow rotators of lower stellar mass are also preferentially located within the different high-density substructures of the cluster. They are virialised within the cluster, thus Virgo members since its formation. They have been shaped by gravitational perturbations occurring within the infalling groups that later formed the cluster. On the contrary, low-mass star-forming systems are extremely rare in the inner regions of the Virgo cluster A, where the density of the intergalactic medium is at its maximum. Our ram pressure stripping models consistently indicate that these star-forming systems can be rapidly deprived of their interstellar medium during their interaction with the intergalactic medium. The lack of gas quenches their star formation activity transforming them into quiescent dwarf ellipticals. This mild transformation does not perturb the kinematic properties of these galaxies which still have rotation curves typical of star-forming systems.

A 30 kpc CHAIN OF “BEADS ON A STRING” STAR FORMATION BETWEEN TWO MERGING EARLY TYPE GALAXIES IN THE CORE OF A STRONG-LENSING GALAXY CLUSTER

New Hubble Space Telescope ultraviolet and optical imaging of the strong-lensing galaxy cluster SDSS J1531+3414 (z=0.335) reveals two centrally dominant elliptical galaxies participating in an ongoing major merger. The interaction is at least somewhat rich in cool gas, as the merger is associated with a complex network of nineteen massive superclusters of young stars (or small tidal dwarf galaxies) separated by ~1 kpc in projection from one another, combining to an estimated total star formation rate of ~5 solar masses per year. The resolved young stellar superclusters are threaded by narrow H-alpha, [O II], and blue excess filaments arranged in a network spanning ~27 kpc across the two merging galaxies. This morphology is strongly reminiscent of the well-known "beads on a string" mode of star formation observed on kpc-scales in the arms of spiral galaxies, resonance rings, and in tidal tails between interacting galaxies. Nevertheless, the arrangement of this star formation relative to the nuclei of the two galaxies is difficult to interpret in a dynamical sense, as no known "beads on a string" systems associated with kpc-scale tidal interactions exhibit such lopsided morphology relative to the merger participants. In this Letter we present the images and follow-up spectroscopy, and discuss possible physical interpretations for the unique arrangement of the young stellar clusters. While we suggest that this morphology is likely to be dynamically short-lived, a more quantitative understanding awaits necessary multiwavelength follow-up, including optical integral field spectroscopy, ALMA sub-mm interferometry, and Chandra X-ray imaging.

SMA OBSERVATIONS ON FAINT SUBMILLIMETER GALAXIES WITHS850&lt; 2 mJy: ULTRA DUSTY LOW-LUMINOSITY GALAXIES AT HIGH REDSHIFT

We obtained SMA observations of eight faint (intrinsic 850 $\mu$m fluxes $<$ 2 mJy) submillimeter galaxies (SMGs) discovered in SCUBA images of the massive lensing cluster fields A370, A2390, and A1689 and detected five. In total, we obtain 5 SMA detections, all of which have de-lensed fluxes $<$1 mJy with estimated total infrared luminosities 10$^{10}-10^{12}$ $L_\odot$, comparable to luminous infrared galaxies (LIRGs) and normal star-forming galaxies. Based on the latest number counts, these galaxies contribute $\sim$70% of the 850 $\mu$m extragalactic background light and represent the dominant star-forming galaxy population in the dusty universe. However, only 40$^{+30}_{-16}$% of our faint SMGs would be detected in deep optical or near-infrared surveys, which suggests many of these sources are at high redshifts ($z \gtrsim 3$) or extremely dusty, and they are not included in current star formation history estimates.

Origin and evolution of structure and nucleosynthesis for galaxies in the local group

The Milky Way is the product of a complex evolution of generations of mergers, collapse, star formation, supernova and collisional heating, radiative and collisional cooling, and ejected nucleosynthesis. Moreover, all of this occurs in the context of the cosmic expansion, the formation of cosmic filaments, dark matter halos, spiral density waves, and emerging dark energy. In this review we summarize observational evidence and discuss recent calculations concerning the formation, evolution nucleosynthesis in the galaxies of the Local Group (LG). In particular, we will briefly summarize observations and simulations for the dwarf galaxies and the two large spirals of the LG. We discuss how galactic halos form within the dark matter filaments that define a super-galactic plane. Gravitational interaction along this structure leads to streaming flows toward the two dominant galaxies in the cluster. These simulations and observations also suggest that a significant fraction of the Galactic halo formed as at large distances and then arrived later along these streaming flows. We also consider the insight provided by observations and simulations of nucleosynthesis both within the galactic halo and dwarf galaxies in the LG.

Emission from the galaxy NGC 1275 at high and very high energies and its origin

The Seyfert galaxy NGC 1275 is the central, dominant galaxy in the Perseus cluster of galaxies. NGC1275 is known as a powerful source of radio and X-ray emission. The well-known extragalactic object NGC 1275 has been observed by the SHALON high-altitude mirror Cherenkov telescopes within the framework of long-term studies of metagalactic gamma-ray sources. In 1996, the SHALON observations revealed a new metagalactic source of very high energy gamma-ray emission coincident in its coordinates with the galaxy NGC 1275. Having analyzed the SHALON data, we have determined such characteristics of NGC 1275 as the spectral energy distributions and images at energies >800 GeV for the first time. The results obtained at high and very high energies are needed for understanding the emission generation processes in an entire wide energy range.

Strong lensing analysis of PLCK G004.5–19.5, aPlanck-discovered cluster hosting a radio relic atz= 0.52

The recent discovery of a large number of galaxy clusters using the Sunyaev-Zel'dovich (SZ) effect has opened a new era on the study of the most massive clusters in the Universe. Multi-wavelength analyses are required to understand the properties of these new sets of clusters, which are a sensitive probe of cosmology. We aim at a multi-wavelength characterization of PLCK G004.5$-$19.5, one of the most massive X-ray validated SZ effect-selected galaxy clusters discovered by the Planck satellite. We have observed PLCK G004.5$-$19.5 with GMOS on Gemini South for optical imaging and spectroscopy, and performed a strong lensing analysis. We also searched for associated radio emission in published catalogs. An analysis of the optical images confirms that this is a massive cluster, with a dominant central galaxy (the BCG) and an accompanying red sequence of galaxies, plus a $14''$-long strong lensing arc. Longslit pectroscopy of 6 cluster members shows that the cluster is at $z=0.516\pm0.002$. We also targeted the strongly lensed arc, and found $z_{\rm arc}=1.601$. We use LensTool to carry out a strong lensing analysis, from which we measure a median Einstein radius $\theta_E(z_s=1.6)\simeq30''$ and estimate an enclosed mass $M_E=2.45_{-0.47}^{+0.45}\times10^{14}\,M_\odot$. By extrapolating an NFW profile we find a total mass $M_{500}^{SL}=4.0_{-1.0}^{+2.1}\times10^{14}M_\odot$. Including a constraint on the mass from previous X-ray observations yields a slightly higher mass, $M_{500}^{SL+X}=6.7_{-1.3}^{+2.6}\times10^{14}M_\odot$, marginally consistent with the value from strong lensing alone. High-resolution radio images from TGSS at 150~MHz reveal that PLCK G004.5$-$19.5 hosts a powerful radio relic on scales $\lesssim500$ kpc. Emission at the same location is also detected in low resolution images at 843~MHz and 1.4~GHz. This is one of the higher redshift radio relics known to date.

X-ray bright active galactic nuclei in massive galaxy clusters – II. The fraction of galaxies hosting active nuclei

We present a measurement of the fraction of cluster galaxies hosting X-ray bright active galactic nuclei (AGN) as a function of clustercentric distance scaled in units of r500. Our analysis employs high-quality Chandra X-ray and Subaru optical imaging for 42 massive X-ray-selected galaxy cluster fields spanning the redshift range 0.2 < z < 0.7. In total, our study involves 176 AGN with bright (R < 23) optical counterparts above a 0.5–8.0 keV flux limit of 10-14 erg cm-2 s-1. When excluding central dominant galaxies from the calculation, we measure a cluster galaxy AGN fraction in the central regions of the clusters that is ∼3 times lower than the field value. This fraction increases with clustercentric distance before becoming consistent with the field at ∼2.5r500. Our data exhibit similar radial trends to those observed for star formation and optically selected AGN in cluster member galaxies, both of which are also suppressed near cluster centres to a comparable extent. These results strongly support the idea that X-ray AGN activity and strong star formation are linked through their common dependence on available reservoirs of cold gas.

IGM Heating and AGN activity in Fossil Galaxy Groups

AbstractFossil galaxy groups are energetically and morphologically ideal environments to study the intergalactic medium (IGM) heating, because their inter-galactic gas is undisturbed due to the lack of recent group scale mergers. We study the role of active galactic nuclei (AGN) in heating the IGM in a sample of five fossil galaxy groups by employing properties at 610 MHz and 1.4 GHz. We find that two of the dominant galaxies in fossil groups, ESO 3060170 and RX J1416.4+2315, are associated with the radio lobes. We evaluate the PdV work of the radio lobes and their corresponding heating power and compare to the X-ray emission loss within cooling radius. Our results show that the power due to mechanical heating is not sufficiently high to suppress the cooling.

HUBBLE SPACE TELESCOPEACS IMAGING OF THE GOALS SAMPLE: QUANTITATIVE STRUCTURAL PROPERTIES OF NEARBY LUMINOUS INFRARED GALAXIES WITHLIR&gt; 1011.4L☉

A {\it Hubble Space Telescope} ({\it HST}) / Advanced Camera for Surveys (ACS) study of the structural properties of 85 luminous and ultraluminous ($L_{\rm IR} > 10^{11.4}$ L$_\odot$) infrared galaxies (LIRGs and ULIRGs) in the Great Observatories All-sky LIRG Survey (GOALS) sample is presented. Two-dimensional GALFIT analysis has been performed on F814W "{\it I}-band" images to decompose each galaxy, as appropriate, into bulge, disk, central PSF and stellar bar components. The fraction of bulge-less disk systems is observed to be higher in LIRGs (35%) than in ULIRGs (20%), with the disk+bulge systems making up the dominant fraction of both LIRGs (55%) and ULIRGs (45%). Further, bulge+disk systems are the dominant late-stage merger galaxy type and are the dominant type for LIRGs and ULIRGs at almost every stage of galaxy-galaxy nuclear separation. The mean {\it I}-band host absolute magnitude of the GOALS galaxies is $-22.64\pm$0.62 mag (1.8$^{+1.4}_{-0.4}$ L$^*_I$), and the mean bulge absolute magnitude in GOALS galaxies is about 1.1 magnitude fainter than the mean host magnitude. Almost all ULIRGs have bulge magnitudes at the high end (-20.6 to - 23.5 mag) of the GOALS bulge magnitude range. Mass ratios in the GOALS binary systems are consistent with most of the galaxies being the result of major mergers, and an examination of the residual-to-host intensity ratios in GOALS binary systems suggests that smaller companions suffer more tidal distortion than the larger companions. We find approximately twice as many bars in GOALS disk+bulge systems (32.8%) than in pure-disk mergers (15.9%) but most of the disk+bulge systems that contain bars are disk-dominated with small bulges. The bar-to-host intensity ratio, bar half-light radius, and bar ellipticity in GOALS galaxies are similar to those found in nearby spiral galaxies.(abridged)

THE NATURE OF FILAMENTARY COLD GAS IN THE CORE OF THE VIRGO CLUSTER

We present a multi-wavelength study of the emission-line nebulae located southeast of the nucleus of M87, the central dominant galaxy of the Virgo Cluster. We report the detection of far-infrared (FIR) [CII] line emission from the nebulae using observations made with Herschel PACS. The infrared line emission is extended and cospatial with optical H{\alpha}+[NII], far-ultraviolet CIV lines, and soft X-ray emission. The filamentary nebulae evidently contain multi-phase material spanning a temperature range of at least 5 orders of magnitude, from ~100 K to ~10^7 K. This material has most likely been uplifted by the AGN from the center of M87. The thermal pressure of the 10^4 K phase appears to be significantly lower than that of the surrounding hot intra-cluster medium (ICM) indicating the presence of additional turbulent and magnetic pressure in the filaments. If the turbulence in the filaments is subsonic then the magnetic field strength required to balance the pressure of the surrounding ICM is B~30-70 {\mu}G. The spectral properties of the soft X-ray emission from the filaments indicate that it is due to thermal plasma with kT~0.5-1 keV, which is cooling by mixing with the cold gas and/or radiatively. Charge exchange can be ruled out as a significant source of soft X-rays. Both cooling and mixing scenarios predict gas with a range of temperatures. This is at first glance inconsistent with the apparent lack of X-ray emitting gas with kT<0.5 keV. However, we show that the missing very soft X-ray emission could be absorbed by the cold gas in the filaments with an integrated hydrogen column density of ~1.6x10^21 cm^-2, providing a natural explanation for the apparent temperature floor to the X-ray emission at kT~0.5 keV. The FIR through ultra-violet line emission is most likely primarily powered by the ICM particles penetrating the cold gas following a shearing induced mixing process.

Galaxy And Mass Assembly (GAMA): the life and times of L★ galaxies

In this work we investigate in detail the effects local environment (groups and pairs) has on galaxies with stellar mass similar to the Milky-Way (L* galaxies). A volume limited sample of 6,150 galaxies is classified to determine emission features, morphological type and presence of a disk. This sample allows for characteristics of galaxies to be isolated (e.g. stellar mass and group halo mass), and their codependencies determined. We observe that galaxy-galaxy interactions play the most important role in shaping the evolution within a group halo, the main role of halo mass is in gathering the galaxies together to encourage such interactions. Dominant pair galaxies find their overall star formation enhanced when the pair's mass ratio is close to 1, otherwise we observe the same galaxies as we would in an unpaired system. The minor galaxy in a pair is greatly affected by its companion galaxy, and whilst the star forming fraction is always suppressed relative to equivalent stellar mass unpaired galaxies, it becomes lower still when the mass ratio of a pair system increases. We find that, in general, the close galaxy-galaxy interaction rate drops as a function of halo mass for a given amount of stellar mass. We find evidence of a local peak of interactions for Milky-Way stellar mass galaxies in Milky-Way halo mass groups. Low mass halos, and in particular Local Group mass halos, are an important environment for understanding the typical evolutionary path of a unit of stellar mass. We find compelling evidence for galaxy conformity in both groups and pairs, where morphological type conformity is dominant in groups, and emission class conformity is dominant in pairs. This suggests that group scale conformity is the result of many galaxy encounters over an extended period of time, whilst pair conformity is a fairly instantaneous response to a transitory interaction.

Long-term observation of Seyfert Galaxies NGC 1275 and 3c 382 at TeV energies by SHALON

Galaxy NGC 1275 is the central dominant galaxy of the Perseus Cluster of Galaxies and is of Seyfert galaxy class. NGC 1275 is known as powerful X-ray and radio source. In 1996 year a new metagalactic source was detected by SHALON at TeV energies. This object was identified with Seyfert galaxy NGC1275. The image and spectral energy distribution of NGC 1275 as well as 3c382 are presented. The recent detection by the Fermi LAT of gamma-rays from the NGC1275 makes the observation of the energy E > 100 GeV part of its broadband spectrum particularly interesting. The available high and very high energy data for NGC 1275 are well fitted in this model with three components.

Very high energy gamma-ray emission of NGC 1275 and 3c382 and the possible activity nature of the Seyfert Galaxies

Galaxy NGC 1275 is the central dominant galaxy of the Perseus Cluster of Galaxies and is of Seyfert galaxy class. NGC 1275 is known as powerful X-ray and radio source. In 1996 year a new metagalactic source was detected by SHALON at TeV energies. This object was identified with Seyfert galaxy NGC1275. The image and spectral energy distribution of NGC 1275 as well as 3c382 are presented. The recent detection by the Fermi LAT of gamma-rays from the NGC1275 makes the observation of the energy E > 100 GeV part of its broadband spectrum particularly interesting. The available high and very high energy data for NGC 1275 are well fitted in this model with three components.

Long-term observations of the Seyfert galaxy NGC 1275 at ultrahigh energies by SHALON mirror Cherenkov telescopes

The Seyfert galaxy NGC 1275 is a central dominant galaxy in the Perseus cluster of galaxies. NGC 1275 is known as a powerful source of radio and X-ray radiations. In 1996, in SHALON telescope observations, a new metagalactic source of gamma radiation of ultrahigh energy > 800 GeV was detected. The position of the radiation source detected in our experiment is consistent in its coordinates with the Seyfert Galaxy NGC 1275. The results obtained at high and ultrahigh energies are necessary to understand the radiation generation processes in the entire wide energy range.

The Herschel Virgo Cluster Survey – XII. FIR properties of optically selected Virgo cluster galaxies

The Herschel Virgo Cluster Survey (HeViCS) is the deepest, confusion-limited survey of the Virgo Cluster at far-infrared (FIR) wavelengths. The entire survey at full depth covers $\sim$55 sq. deg. in 5 bands (100-500 \micron), encompassing the areas around the central dominant elliptical galaxies (M87, M86 & M49) and extends as far as the NW cloud, the W cloud and the Southern extension. The survey extends beyond this region with lower sensitivity so that the total area covered is 84 sq. deg. In this paper we describe the data, the data acquisition techniques and present the detection rates of the optically selected Virgo Cluster Catalogue (VCC). We detect 254 (34%) of 750 VCC galaxies found within the survey boundary in at least one band and 171 galaxies are detected in all five bands. For the remainder of the galaxies we have measured strict upper limits for their FIR emission. The population of detected galaxies contains early- as well as late-types although the latter dominate the detection statistics. We have modelled 168 galaxies, showing no evidence of a strong synchrotron component in their FIR spectra, using a single-temperature modified blackbody spectrum with a fixed emissivity index ($\beta = 2$). A study of the $\chi^2$ distribution indicates that this model is not appropriate in all cases, and this is supported by the FIR colours which indicate a spread in $\beta$=1--2. Statistical comparison of the dust mass and temperature distributions from 140 galaxies with $\chi^2_{dof=3} < 7.8$ (95% confidence level) shows that late-types have typically colder, more massive dust reservoirs; the early-type dust masses have a mean of ${\rm log}(<M> / M_{\sun}) = 6.3 \pm 0.3 $, while for late-types ${\rm log}(<M> / M_{\sun}) =7.1 \pm 0.1$... (abridged)