Context. We have carried out a semi-automated search for planetary nebulae (PNe) in the INT photometric H-alpha survey (IPHAS) catalogue. We present the PN search and the list of selected candidates. ...We cross correlate the selected candidates with a number of existing infrared galactic surveys in order to gain further insight into the nature of the candidates. Spectroscopy of a subset of objects is used to estimate the number of PNe present in the entire candidate list. Aims. The overall aim of the IPHAS PN project is to carry out a deep census of PNe in the northern Galactic plane, an area where PN detections are clearly lacking. Methods. The PN search is carried out on the IPHAS photometric catalogue. The candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the objects and the final candidate selection is made visually. Results. From the original list of ~600 million IPHAS detections we have selected a total of 1005 objects. Of these, 224 are known objects, leaving us with 781 PN candidates. Based on the initial follow-up spectroscopy, we expect the list to include very young and proto-PNe in addition to genuine, normal PNe (~16%) and emission line objects other than PNe. We present additional criteria to select the most probable PN candidates from our candidate list.
As part of the Herschel Multi-tiered Extragalactic Survey we have investigated the rest-frame far-infrared (FIR) properties of a sample of more than 4800 Lyman break galaxies (LBGs) in the Great ...Observatories Origins Deep Survey North field. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z < 1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV -- U and U -- R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. The UV-to-FIR spectral energy distributions of the objects detected in the rest-frame FIR are investigated using the code CIGALE to estimate physical parameters. We find that LBGs detected by SPIRE are high-mass, luminous infrared galaxies. It appears that LBGs are located in a triangle-shaped region in the A FUV versus log L FUV = 0 diagram limited by A FUV = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom right to the top left of the diagram. This upper envelop can be used as upper limits for the UV dust attenuation as a function of L FUV. The limits of this region are well explained using a closed-box model, where the chemical evolution of galaxies produces metals, which in turn lead to higher dust attenuation when the galaxies age.
We present the results of a gravitational lensing analysis of the bright z s = 2.957 submillimeter galaxy (SMG) HERMES found in the Herschel/SPIRE science demonstration phase data from the Herschel ...Multi-tiered Extragalactic Survey (HerMES) project. The high-resolution imaging available in optical and near-IR channels, along with CO emission obtained with the Plateau de Bure Interferometer, allows us to precisely estimate the intrinsic source extension and hence estimate the total lensing magnification to be Delta *m = 10.9 ? 0.7. We measure the half-light radius R eff of the source in the rest-frame near-UV and V bands that characterize the unobscured light coming from stars and find R eff, * = 2.0 ? 0.1 kpc, in good agreement with recent studies on the SMG population. This lens model is also used to estimate the size of the gas distribution (R eff, gas = 1.1 ? 0.5 kpc) by mapping back in the source plane the CO (J = 5 -> 4) transition line emission. The lens modeling yields a relatively large Einstein radius R Ein = 410 ? 002, corresponding to a deflector velocity dispersion of 483 ? 16 km s--1. This shows that HERMES is lensed by a galaxy group-size dark matter halo at redshift z l ~ 0.6. The projected dark matter contribution largely dominates the mass budget within the Einstein radius with f dm(< R Ein) ~ 80%. This fraction reduces to f dm(< R eff, G1 4.5 kpc) ~ 47% within the effective radius of the main deflecting galaxy of stellar mass M *, G1 = 8.5 ? 1.6 X 1011 M . At this smaller scale the dark matter fraction is consistent with results already found for massive lensing ellipticals at z ~ 0.2 from the Sloan Lens ACS Survey.
Aims. The aim of the project is to improve our current knowledge of the density of T dwarfs and the shape of the substellar initial mass function by identifying a magnitude-limited sample of T dwarfs ...in the full southern sky. Methods. We present the results of a photometric search aimed at discovering cool brown dwarfs in the southern sky imaged at infrared wavelengths by the Visible and Infrared Survey Telescope for Astronomy (VISTA) and the Wide Infrared Survey Explorer (WISE) satellite mission. We combined the first data release (DR1) of the VISTA Hemisphere Survey (VHS) and the WISE preliminary data release to extract candidates with red mid-infrared colours and near- to mid-infrared colours characteristics of cool brown dwarfs. Results. The VHS DR1 vs. WISE search returned tens of T dwarf candidates, 13 of which are presented here, including two previously published in the literature and five new ones confirmed spectroscopically with spectral types between T4.5 and T8. We estimate that the two T6 dwarfs lie within 16 pc and the T4.5 within 25 pc. The remaining three are 30–50 pc distant. The only T7 dwarf in our sample is the faintest of its spectral class with J = 19.28 mag. The other six T dwarf candidates remain without spectroscopic follow-up. We also improve our knowledge on the proper motion accuracy for three bright T dwarfs by combining multi-epoch data from public databases (DENIS, 2MASS, VHS, WISE, Spitzer).
ABSTRACT
We present a combined galaxy–quasar approach to template‐fitting photometric redshift techniques and show the method to be a powerful one.
The code (ImpZ) is presented, developed and applied ...to two spectroscopic redshift catalogues, namely the Isaac Newton Telescope Wide‐Angle Survey ELAIS N1 and N2 fields and the Chandra Deep Field North. In particular, optical size information is used to improve the redshift determination. The success of the code is shown to be very good, with Δz/(1 +z) constrained to within 0.1 for 92 per cent of the galaxies in our sample.
The extension of template fitting to quasars is found to be reasonable, with Δz/(1 +z) constrained to within 0.25 for 68 per cent of the quasars in our sample. Various template extensions into the far‐ultraviolet are also tested.
Context. The extensive stellar spectroscopic datasets that are available for studies in Galactic Archeaology thanks to, for example, the Gaia-ESO Survey, now benefit from having a significant number ...of targets that overlap with asteroseismology projects such as Kepler, K2, and CoRoT. Combining the measurements from spectroscopy and asteroseismology allows us to attain greater accuracy with regard to the stellar parameters needed to characterise the stellar populations of the Milky Way. Aims. The aim of this Gaia-ESO Survey special project is to produce a catalogue of self-consistent stellar parameters by combining measurements from high-resolution spectroscopy and precision asteroseismology. Methods. We carried out an iterative analysis of 90 K2@Gaia-ESO red giants. The spectroscopic values of Teff were used as input in the seismic analysis to obtain log g values. The seismic estimates of log g were then used to re-determine the spectroscopic values of Teff and Fe/H. Only one iteration was required to obtain parameters that are in good agreement for both methods and, thus, to obtain the final stellar parameters. A detailed analysis of outliers was carried out to ensure a robust determination of the parameters. The results were then combined with Gaia DR2 data to compare the seismic log g with a parallax-based log g and to investigate instances of variations in the velocity and possible binaries within the dataset. Results. This analysis produced a high-quality catalogue of stellar parameters for 90 red giant stars from K2@Gaia-ESO that were determined through iterations between spectroscopy and asteroseismology. We compared the seismic gravities with those based on Gaia parallaxes to find an offset which is similar to other studies that have used asteroseismology. Our catalogue also includes spectroscopic chemical abundances and radial velocities, as well as indicators for possible binary detections.
We analyse the first publicly released deep field of the UK Infrared Deep Sky Survey (UKIDSS) Deep eXtragalactic Survey to identify candidate galaxy overdensities at z∼ 1 across ∼1 deg2 in the ...ELAIS-N1 field. Using I−K, J−K and K− 3.6 μm colours, we identify and spectroscopically follow up five candidate structures with Gemini/Gemini Multi-Object Spectrograph and confirm that they are all true overdensities with between five and 19 members each. Surprisingly, all five structures lie in a narrow redshift range at z= 0.89 ± 0.01, although they are spread across 30 Mpc on the sky. We also find a more distant overdensity at z= 1.09 in one of the spectroscopic survey regions. These five overdense regions lying in a narrow redshift range indicate the presence of a supercluster in this field and by comparing with mock cluster catalogues from N-body simulations we discuss the likely properties of this structure. Overall, we show that the properties of this supercluster are similar to the well-studied Shapley and Hercules superclusters at lower redshift.
We have analysed the rest-frame far-infrared properties of a sample of massive (M★ > 1011 M⊙) galaxies at 2 ≲z≲ 3 in the Great Observatories Origins Deep Survey-North (GOODS-N) field using the ...Spectral and Photometric Imaging Receiver (SPIRE) instrument aboard the Herschel Space Observatory. To conduct this analysis we take advantage of the data from the Herschel Multi-tiered Extragalactic Survey (HerMES) key programme. The sample comprises 45 massive galaxies with structural parameters characterized with HST NICMOS-3. We study detections at submm Herschel bands, together with Spitzer 24-μm data, as a function of the morphological type, mass and size. We find that 26/45 sources are detected at MIPS 24 μm and 15/45 (all MIPS 24-μm detections) are detected at SPIRE 250 μm, with disc-like galaxies more easily detected. We derive star formation rates (SFRs) and specific star formation rates (sSFRs) by fitting the spectral energy distribution of our sources, taking into account non-detections for SPIRE and systematic effects for MIPS derived quantities. We find that the mean SFR for the spheroidal galaxies (∼50–100 M⊙ yr−1) is substantially (a factor ∼3) lower than the mean value presented by disc-like galaxies (∼250–300 M⊙ yr−1).
We present the final band-merged European Large-Area ISO Survey (ELAIS) Catalogue at 6.7, 15, 90 and 175 μm, and the associated data at U, g′, r′, i′, Z, J, H, K and 20 cm. The origin of the survey, ...infrared and radio observations, data-reduction and optical identifications are briefly reviewed, and a summary of the area covered and the completeness limit for each infrared band is given. A detailed discussion of the band-merging and optical association strategy is given. The total Catalogue consists of 3762 sources. 23 per cent of the 15-μm sources and 75 per cent of the 6.7-μm sources are stars. For extragalactic sources observed in three or more infrared bands, colour–colour diagrams are presented and discussed in terms of the contributing infrared populations. Spectral energy distributions (SEDs) are shown for selected sources and compared with cirrus, M82 and Arp220 starburst, and active galactic nuclei (AGN) dust torus models. Spectroscopic redshifts are tabulated, where available. For the N1 and N2 areas, the Isaac Newton Telescope ugriz Wide Field Survey permits photometric redshifts to be estimated for galaxies and quasars. These agree well with the spectroscopic redshifts, within the uncertainty of the photometric method ∼10 per cent in (1 +z) for galaxies. The redshift distribution is given for selected ELAIS bands and colour–redshift diagrams are discussed. There is a high proportion of ultraluminous infrared galaxies (log10 of 1–1000 μm luminosity Lir > 12.22) in the ELAIS Catalogue (14 per cent of 15-μm galaxies with known z), many with Arp220-like SEDs. 10 per cent of the 15-μm sources are genuine optically blank fields to r′= 24: these must have very high infrared-to-optical ratios and probably have z > 0.6, so are high-luminosity dusty starbursts or Type 2 AGN. Nine hyperluminous infrared galaxies (Lir > 13.22) and nine extremely red objects (EROs) (r−K > 6) are found in the survey. The latter are interpreted as ultraluminous dusty infrared galaxies at z∼ 1. The large numbers of ultraluminous galaxies imply very strong evolution in the star formation rate between z= 0 and 1. There is also a surprisingly large population of luminous (Lir > 11.5), cool (cirrus-type SEDs) galaxies, with Lir−Lopt > 0, implying AV > 1.
This paper presents a study of the environments of SDSS quasi-stellar objects (QSOs) in the Spitzer Extragalactic Representative Volume Survey (SERVS). We concentrate on the high-redshift QSOs as ...these have not been studied in large numbers with data of this depth before. We use the IRAC 3.6-4.5 Delta *mm color of objects and ancillary r-band data to filter out as much foreground contamination as possible. This technique allows us to find a significant (>4 Delta *s) overdensity of galaxies around QSOs in a redshift bin centered on z ~ 2.0 and an (>2 Delta *s) overdensity of galaxies around QSOs in a redshift bin centered on z ~ 3.3. We compare our findings to the predictions of a semi-analytic galaxy formation model, based on the Delta *LCDM MILLENNIUM simulation, and find for both redshift bins that the model predictions match well the source density we have measured from the SERVS data.
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