- ID:
- ivo://CDS.VizieR/J/ApJ/762/77
- Title:
- PM2GC mass-limited sample surface photometry
- Short Name:
- J/ApJ/762/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for massive and compact galaxies (superdense galaxies, hereafter SDGs) at z=0.03-0.11 in the Padova-Millennium Galaxy and Group Catalogue (PM2GC), a spectroscopically complete sample representative of the general field population of the local universe. We find that compact galaxies with radii and mass densities comparable to high-z massive and passive galaxies represent 4.4% of all galaxies with stellar masses above 3x10^10^M_{sun}_, yielding a number density of 4.3x10^-4^h^3^/Mpc^3^. Most of them are S0s (70%) or ellipticals (23%), are red, and have intermediate-to-old stellar populations, with a median luminosity-weighted age of 5.4Gyr and a median mass-weighted age of 9.2Gyr. Their velocity dispersions and dynamical masses are consistent with the small radii and high stellar mass estimates. Comparing with the WINGS sample of cluster galaxies at similar redshifts, the fraction of SDGs is three times smaller in the field than in clusters, and cluster SDGs are on average 4Gyr older than field SDGs. We confirm the existence of a universal trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. As a consequence, the median mass-size relation shifts toward smaller radii for galaxies with older stars, but the effect is much more pronounced in clusters than in the field. Our results show that, on top of the well-known dependence of stellar age on galaxy mass, the luminosity-weighted age of galaxies depends on galaxy compactness at fixed mass and, for a fixed mass and radius, on environment. This effect needs to be taken into account in order not to overestimate the evolution of galaxy sizes from high to low z. Our results and hierarchical simulations suggest that a significant fraction of the massive compact galaxies at high z have evolved into compact galaxies in galaxy clusters today. When stellar age and environmental effects are taken into account, the average amount of size evolution of individual galaxies between high and low z is mild, a factor ~1.6.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/548/A106
- Title:
- PMN J0948+0022 radio-to-gamma-ray monitoring
- Short Name:
- J/A+A/548/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present more than three years of observations at different frequencies, from radio to high-energy gamma-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.585). This source is the first NLS1 detected at energies above 100 MeV and therefore can be considered the prototype of this emerging new class of gamma-ray emitting active galactic nuclei (AGN). The observations performed from 2008 August 1 to 2011 December 31 confirmed that PMN J0948+0022 generates a powerful relativistic jet, able to develop an isotropic luminosity at gamma-rays of the order of 10^48^erg/s, at the level of powerful quasars. The evolution of the radiation emission of this source in 2009 and 2010 followed the canonical expectations of relativistic jets, with correlated multiwavelength variability (gamma-rays followed by radio emission after a few months), but it was difficult to retrieve a similar pattern in the light curves of 2011. The comparison of gamma-ray spectra before and including 2011 data suggested that there was a softening of the high-energy spectral slope. We selected five specific epochs to be studied by modelling the broad-band spectrum, characterised by an outburst at gamma-rays or very low/high flux at other wavelengths. The observed variability can largely be explained either by changes in the injected power, the bulk Lorentz factor of the jet or the electron spectrum. The characteristic time scale of doubling/halving flux ranges from a few days to a few months, depending on the frequency and the sampling rate. The shortest doubling time scale at gamma-rays is 2.3+/-0.5days. These small values underline the need of highly-sampled multiwavelength campaigns to better understand the physics of these sources.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A61
- Title:
- PM-selected stars of Hercules galaxy
- Short Name:
- J/A+A/570/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Discovered in the last decade as overdensities of resolved stars, the ultra-faint dwarfs (UFDs) are among the least luminous, most dark-matter dominated, and most metal-poor galaxies known today. They appear as sparse, loose objects with high mass-to-light ratios. Hercules is the prototype of the UFD galaxies. To date, there are still no firm constraints on its total luminosity due to the difficulty of disentangling Hercules bona-fide stars from the severe Galactic field contamination. To better constrain Hercules properties, we aim at removing foreground and background contaminants in the galaxy field using the proper motions of the Milky Way stars and the colour-colour diagram. We have obtained images of Hercules in the r_Sloan_ , B_Bessel_ and U_spec_ bands with the Large Binocular Telescope (LBT) and LBC-BIN mode capabilities. The r_Sloan_ new dataset combined with data from the LBT archive span a time baseline of about 5yr, allowing us to measure proper motions of stars in the Hercules direction for the first time. The U_spec_ data along with existing LBT photometry allowed us to use colour-colour diagram to further remove the field contamination. Description: The Hercules ultra-faint dwarf (UFD) galaxy (J2000 position 16:31:02.0+12:47:25.6) was observed with the Large Binocular Camera (LBC) at the LBT located on Mount Graham in Arizona. The LBC is a wide field imager (4 CCDs, 2Kx4.5K pixels each) with a FoV of ~23'x 23' and a resolution of 0.225"/pix. We employed both archival and proprietary data to have the longest available time baseline. File table2 contains the final catalogue of 528 PM-selected sources. From left to right we report: the source identity (Col. 1), right ascension and declination (Col. 2-3), U_spec_, B_Bessel_ and r_Sloan_ magnitudes with their uncertainty (Col. 4-6), displacement with its uncertainty (Col. 7)
- ID:
- ivo://CDS.VizieR/J/A+A/495/447
- Title:
- PN and HII regions in NGC6822
- Short Name:
- J/A+A/495/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Images obtained with the CTIO 4-m telescope and the MOSAIC-2 wide field camera in [OIII] 5007 and Halpha on-band and off-band filters are analyzed to search for emission line objects in the dwarf galaxy NGC 6822. In particular we search for planetary nebula (PN) candidates. In addition, imaging and spectroscopy of a sub-sample of objects obtained with the ESO VLT and FORS 2 spectrograph are used to calibrate the MOSAIC imaging. In the continuum-subtracted images, a large number of line emission regions were detected, for which we measured instrumental magnitudes in all the filters. The [OIII] 5007 and Halpha+[NII] magnitudes were calibrated with the spectroscopy.
2835. PNe in 5 nearby galaxies
- ID:
- ivo://CDS.VizieR/J/ApJ/703/894
- Title:
- PNe in 5 nearby galaxies
- Short Name:
- J/ApJ/703/894
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the second step in our investigation of the mass-to-light ratio of spiral disks, we present the results of a spectroscopic survey of planetary nebulae (PNe) in five nearby, low-inclination galaxies: IC 342, M74 (NGC 628), M83 (NGC 5236), M94 (NGC 4736), and M101 (NGC 5457). Using 50 setups of the WIYN/Hydra and Blanco/Hydra spectrographs, and 25 observations with the Hobby-Eberly Telescope's Medium Resolution Spectrograph, we determine the radial velocities of 99, 102, 162, 127, and 48 PNe, respectively, to a precision better than 15km/s. Although the main purpose of this data set is to facilitate dynamical mass measurements throughout the inner and outer disks of large spiral galaxies, our spectroscopy has other uses as well. Here, we co-add these spectra to show that, to first order, the [OIII] and Balmer line ratios of PNe vary little over the top ~1.5mag of the PN luminosity function.
2836. PNe in six galaxies
- ID:
- ivo://CDS.VizieR/J/ApJ/577/31
- Title:
- PNe in six galaxies
- Short Name:
- J/ApJ/577/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of [O III] {lambda}5007 surveys for planetary nebulae (PNe) in six galaxies: NGC 2403, NGC 3115, NGC 3351, NGC 3627, NGC 4258, and NGC 5866. Using on-band/off-band [O III] {lambda}5007 images, as well as images taken in H{alpha}, we identify samples of PNe in these galaxies and derive their distances using the planetary nebula luminosity function (PNLF).
- ID:
- ivo://CDS.VizieR/J/ApJ/721/369
- Title:
- PNe in the elliptical galaxy NGC 821
- Short Name:
- J/ApJ/721/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a slitless spectroscopy method with the 8.2m Subaru telescope and its FOCAS Cassegrain spectrograph, we have increased the number of planetary nebula (PN) detections and PN velocity measurements in the flattened elliptical galaxy NGC 821. A comparison with the detections reported previously by the Planetary Nebulae Spectrograph group indicates that we have confirmed most of their detections. The velocities measured by the two groups, using different telescopes, spectrographs, and slitless techniques, are in good agreement. We have built a combined sample of 167 PNs and have confirmed the Keplerian decline of the line-of-sight velocity dispersion reported previously. We also confirm misaligned rotation from the combined sample. A dark matter halo may exist around this galaxy, but it is not needed to keep the PN velocities below the local escape velocity as calculated from the visible mass. We have measured the m(5007) magnitudes of 145 PNs and produced a statistically complete sample of 40 PNs in NGC 821. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 31.4mag, equivalent to 19Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/65
- Title:
- PNe in the Virgo elliptical galaxy NGC 4649
- Short Name:
- J/ApJ/736/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a slitless spectroscopy method with (1) the 8.2m Subaru telescope and its FOCAS Cassegrain spectrograph and (2) the ESO Very Large Telescope unit 1 (Antu) and its FORS2 Cassegrain spectrograph, we have detected 326 planetary nebulae (PNs) in the giant Virgo elliptical galaxy NGC 4649 (M60) and measured their radial velocities. After rejecting some PNs more likely to belong to the companion galaxy NGC 4647, we have built a catalog with kinematic information for 298 PNs in M60. Using these radial velocities, we have concluded that they support the presence of a dark matter halo around M60. Based on an isotropic, two-component Hernquist model, we estimate the dark matter halo mass within 3R_e_ to be 4x10^11^M_{sun}_, which is almost one-half of the total mass of about 10^12^M_{sun}_ within 3R_e_. This total mass is similar to that estimated from globular cluster, XMM-Newton, and Chandra observations. The dark matter becomes dominant outside. More detailed dynamical modeling of the PN data is being published in a companion paper. We have also measured the m(5007) magnitudes of many of these PNs and built a statistically complete sample of 218 PNs. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 30.7+/-0.2mag, equivalent to 14+/-1Mpc. This confirms an earlier PNLF distance measurement based on a much smaller sample. The PNLF distance modulus remains smaller than the surface brightness fluctuation distance modulus by 0.4mag.
- ID:
- ivo://CDS.VizieR/J/MNRAS/351/1071
- Title:
- POINT-AGAPE Survey. M31 variables
- Short Name:
- J/MNRAS/351/1071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the purposes of identifying microlensing events, the POINT-AGAPE collaboration has been monitoring the Andromeda galaxy (M31) for three seasons (1999-2001) with the Wide Field Camera on the Isaac Newton Telescope. In each season, data are taken for one hour per night for roughly 60 nights during the six months that M31 is visible. The two 33x33arcmin^2^ fields of view straddle the central bulge, northwards and southwards. We have calculated the locations, periods and brightness of 35 414 variable stars in M31 as a by-product of the microlensing search. The variables are classified according to their period and brightness. Rough correspondences with classical types of variable star (such as Population I and II Cepheids, Miras and semiregular long-period variables) are established. The spatial distribution of Population I Cepheids is clearly associated with the spiral arms, while the central concentration of the Miras and long-period variables varies noticeably, the brighter and the shorter period Miras being much more centrally concentrated.
- ID:
- ivo://CDS.VizieR/J/AJ/154/268
- Title:
- Point & compact H{alpha} sources in the inner of M33
- Short Name:
- J/AJ/154/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A variety of interesting objects such as Wolf-Rayet stars, tight OB associations, planetary nebulae, X-ray binaries, etc., can be discovered as point or compact sources in H{alpha} surveys. How these objects distribute through a galaxy sheds light on the galaxy star formation rate and history, mass distribution, and dynamics. The nearby galaxy M33 is an excellent place to study the distribution of H{alpha}-bright point sources in a flocculant spiral galaxy. We have reprocessed an archived WIYN continuum-subtracted H{alpha} image of the inner 6.5'x6.5' of M33 and, employing both eye and machine searches, have tabulated sources with a flux greater than approximately 10^-15^ erg/cm^2^/s. We have effectively recovered previously mapped H II regions and have identified 152 unresolved point sources and 122 marginally resolved compact sources, of which 39 have not been previously identified in any archive. An additional 99 H{alpha} sources were found to have sufficient archival flux values to generate a Spectral Energy Distribution. Using the SED, flux values, H{alpha} flux value, and compactness, we classified 67 of these sources.
