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Paper text:
the dwarf elliptical galaxy class has been a point of much interest in recent years .
photometric surveys have revealed a whole range of substructures : spiral arms , bars , disks , twists , lenses ( e.g. @xcite , @xcite , @xcite , @xcite , @xcite , @xcite ) . through the kinematic studies of , e.g. @xcite , @xcite , @xcite we have learned about the variety of rotation patterns , and stellar populations analyses
have shown a variety of ages , metallicities , and their gradients ( e.g. @xcite , @xcite , @xcite ) .
thus , des have come a long way from being considered simple low - mass extension of giant ellipticals to having their complicated structure and history unveiled in numerous studies which led to the conclusion that they are most likely environmentally - transformed late - type galaxies ( see e.g. the review in @xcite ) .
since the effect of such transformation processes depends on the local environment density , we would expect galaxy properties to change with clustrocentric distance .
indeed , such trends have been found for the shape and the degree of substructure in virgo ( @xcite ) , and for the ages and metallicities of both virgo ( @xcite ) and coma des ( @xcite ) . with our integral - field spectroscopic data for virgo des
we have now turned to investigating their dynamical properties and the connection thereof to the location in the cluster .
stellar velocity _ v _ maps of our full sample shown here together to emphasize the kinematic variety .
the level of rotation is not tied to flattening , we see kinematics twists ( vcc0523 , id0918 ) and kinematically - decoupled components ( id0650 and id0918 ) .
a full set of maps and profiles ( _ v _ , @xmath0 , and their errors ) can be found in @xcite .
, title="fig:",width=566 ]    details on data selection , observations and data reduction are presented in @xcite . in short
, we observed 12 des : 9 in the virgo cluster and 3 in the field .
our objects span a wide range of ellipticities and distances from the cluster s center .
the observations were carried out in jan 2010 and apr 2011 ( 8 nights in total ) using the wht / sauron instrument at the roque de los muchachos observatory in la palma , with each galaxy typically exposed for 5h .
for the extraction and calibration of the data we followed the procedures described in @xcite using the specifically designed xsauron software developed at the centre de recherche astrophysique de lyon ( cral ) .
the data were spatially binned to achieve the required minimum signal - to - noise ratio of 30 per pixel .
the stellar absorption - line kinematics were derived for each galaxy by directly fitting the spectra in the pixel space using the penalized pixel - fitting method ( ppxf ) of @xcite .
these velocity maps shown in figure  [ fig1 ] are the best example of the level of variety we are finding .
the maps show varying degrees of rotation : from @xmath140 km / s for vcc0523 to virtually no rotation for vcc1261 .
rotation seems to be uncorrelated with flattening since we see all possible combinations of both .
in addition to that , in two galaxies ( id0650 and id0918 ) we observe large - scale kinematically - decoupled components , counter - rotating with regard to the main bodies . also , kinematic twists are seen in vcc0523 and id0918 .    to relate this variety to the formation histories of these galaxies ,
we need to tie the results to the transformation mechanisms acting in cluster
. the combined influence of ram - pressure stripping and harassment is the most likely answer , given that they allow for the random shaping of galaxy properties , based on the variety initial infall parameters ( disk inclination and orbit type ) and the number of encounters with large galaxies .
since des used to be thought of as a low - luminosity extension of giant ellipticals ( es ) , we present here a comparison of the kinematic properties of our des and early - type giants ( etgs ) of @xcite . to estimate the amount of rotation in our objects we have therefore decided to use the new @xmath2 parameter defined in @xcite ( figure  [ fig2 ] ) .
@xmath2 is better suited for angular momentum estimate than the traditionally employed v/@xmath0 .    for the most part des
behave like the members of the fast - rotator family : their integrated @xmath3 values are above or on the line that divides the etg group into slow and fast rotators .
their @xmath2 profiles also tend to increase for larger r / r@xmath4 or lie in between those of slow- and fast - rotator groups .
a direct comparison is , however , tricky .
a range of differences stand behind each type that include photometric , kinematic , dynamic , and x - ray properties ( see , e.g. , @xcite , @xcite ) .
thus , the empirical dividing line can not be easily used to accommodate des in the same diagram . moreover , by their very nature the data for des are noisier , which will produce a positive offset in the calculated @xmath2 .
one , thus , needs to be cautious when devising their analysis approach in such cases as ours .
_ left _ : radial @xmath2 profiles for the combined sample of des from this study ( thick red lines ) and etgs of @xcite ( thin grey lines ) .
slow - rotating etgs have profiles that are decreasing or nearly flat and fast - rotators have increasing profiles . _
right _ : @xmath2 versus ellipticity for the same sample ( des  red diamonds , es  black triangles ) .
the green solid line corresponds to @xmath5 , the threshold separating the fast- and slow - rotator families defined by @xcite ) , title="fig:",width=275 ]   _ left _ : radial @xmath2 profiles for the combined sample of des from this study ( thick red lines ) and etgs of @xcite ( thin grey lines ) .
slow - rotating etgs have profiles that are decreasing or nearly flat and fast - rotators have increasing profiles . _
right _ : @xmath2 versus ellipticity for the same sample ( des  red diamonds , es  black triangles ) .
the green solid line corresponds to @xmath5 , the threshold separating the fast- and slow - rotator families defined by @xcite ) , title="fig:",width=275 ]    nevertheless , these results support the claim of des having late - type origin .
giant fast rotators ( most of which are s0s ) have properties more similar to those of late - type galaxies .
s0s are believed to be faded spirals ( e.g. @xcite ) , so the fact that our des show a similar level of variety as the sauron survey s fast rotators only strengthens the argument in favor of them being transformed late - type galaxies .      as we have already discussed in @xcite , the analysis of any property trends with clustrocentric distance , should be performed using intrinsic ( i.e. deprojected ) distances in order to minimize the projection bias when dealing with incomplete samples .
we show this effect in the left panel of figure  [ fig3 ] where a trend of rotational support versus virgocentric distance is shown for both projected and intrinsic distances .
our results , albeit based on a limited - size sample , tentatively show little if any relation between the two aforementioned quantities .
we have also investigated the relation between the dark matter fraction and the location in the cluster , motivated by the simulations of @xcite and @xcite who suggest that ( at a fixed radius ) dark matter might be lost more easily due to its different orbital distribution .
the preliminary results of this analysis are shown in the right panel of figure  [ fig3 ] .
the total ( dark+stellar ) masses come from jeans axisymmetric mge models @xcite which we constructed combining our sauron stellar kinematics and sdss r - band imaging . to obtain the stellar mass estimates we used the @xcite sdss g - r colors and the color - mass conversion of @xcite      _ left _ : specific angular momentum @xmath6 virgocentric distance . for all galaxies both intrinsic and projected distances
are shown .
no radial trend is found when intrinsic distances are used ( @xcite ) .
_ right _ : dark - to - stellar matter ratio as a function of virgocentric distance .
intrinsic distances are plotted where available , otherwise projected distances are provided .
a tentative trend is seen : the ratio increases with increasing distance ( ry et al .
, in prep . ) , title="fig:",width=275 ]
_ left _ : specific angular momentum @xmath6 virgocentric distance .
for all galaxies both intrinsic and projected distances are shown .
no radial trend is found when intrinsic distances are used ( @xcite ) .
_ right _ : dark - to - stellar matter ratio as a function of virgocentric distance .
intrinsic distances are plotted where available , otherwise projected distances are provided .
a tentative trend is seen : the ratio increases with increasing distance ( ry et al .
, in prep . )
, title="fig:",width=275 ]
the variety of properties we find does not mean that we should necessarily look for separate formation mechanisms for each de subclass .
the environmental reshaping processes are to a certain degree random processes that are able to produce different products from similar input objects .
therefore , an effort has to be made to create a big picture and build a fully consistent transformation scenario .
the results presented here are only indicative of possible trends , given the sample size and , in the case of dark matter trend , the uncertainties on the mass estimates . nevertheless , studying a small number of galaxies in great detail
has ( in fact , always ) been a necessary first step , as it is in this way that tentative trends are found that can later be investigated with larger samples .
it is also a good starting point for a discussion on what is actually expected in terms of trends from a theoretical point of view .
what is important is the predicted timescales of transformation events , and their comparison with the average cluster crossing times .
this information makes it possible to determine whether a given scenario is properly predicting the fate of infalling galaxies or not .
if the different timescales do not add up , then the simulations need to be revised and/or perhaps other scenarios considered .    drawing conclusions from comparing the different timescales
is not a straightforward task . to name a few problems , galaxies orbits in clusters differ from one another : at the same distance form the center one galaxy might be approaching the center on its first pass while another will have travelled across the cluster already more than once .
we do not know how long it has been since galaxies fell into a cluster , we are also limited in our analysis by projection effects : galaxies appearing to be in the center might in fact be located at any clustrocentric distance .    thus , in order to try to tackle the obstacles discussed above and have a chance at disentangling the importance of different processes , a holistic approach needs to be applied that combines dynamical and stellar populations studies of large data samples . with this approach in mind ,
we hope not only to give a qualitative assessment of various formation mechanisms , but also to disentangle the relative strength and contributions of each of them , thus quantitatively determining the actual transformation paths for these galaxies .
ar would like to thank the spanish astronomical society for financial assistance to attend the society s @xmath7 scientific meeting in valencia in july 2012 where this work was presented .
jfb acknowledges support from the ramn y cajal program financed by the spanish ministry of economy and competitiveness ( mineco ) .
this research has been supported by the spanish ministry of economy and competitiveness ( mineco ) under grants aya2010 - 21322-c03 - 02 and aib-2010-de-00227 .
ar acknowledges the repeated hospitality of the max planck institute for astronomy in heidelberg , to which collaborative visits contributed to the quality of this work .
we show the effects of environmental evolution on virgo cluster and field dwarf elliptical galaxies ( des ) , presenting the first large - scale integral - field spectroscopic data for this galaxy class . 
 the great variety of morphological , kinematic , and stellar population parameters seen in our data supports the claim that des are defunct dwarf spiral / irregular galaxies and points to a formation scenario that allows for a stochastic shaping of galaxy properties . 
 we further investigate the properties of our sample by analyzing its kinematic and dynamical properties . 
 we compare the level of rotational support of des and giant early - type galaxies and show that the properties of the former largely resemble those of giant fast - rotators . 
 based on our data , no trend exists between the level of rotational support in des and their location in the cluster . 
 however , a tentative trend is seen in dark matter fraction : it increases for larger virgocentric distances .