2MTF – VI. Measuring the velocity power spectrum Howlett, Cullan; Staveley-Smith, Lister; Elahi, Pascal J ...
Monthly Notices of the Royal Astronomical Society,
11/2017, Volume:
471, Issue:
3
Journal Article
Peer reviewed
Open access
Abstract
We present measurements of the velocity power spectrum and constraints on the growth rate of structure fσ8, at redshift zero, using the peculiar motions of 2062 galaxies in the completed ...2MASS Tully–Fisher survey (2MTF). To accomplish this we introduce a model for fitting the velocity power spectrum including the effects of non-linear redshift space distortions (RSD), allowing us to recover unbiased fits down to scales k = 0.2 h Mpc−1 without the need to smooth or grid the data. Our fitting methods are validated using a set of simulated 2MTF surveys. Using these simulations we also identify that the Gaussian distributed estimator for peculiar velocities of Watkins & Feldman is suitable for measuring the velocity power spectrum, but sub-optimal for the 2MTF data compared to using magnitude fluctuations δm, and that, whilst our fits are robust to a change in fiducial cosmology, future peculiar velocity surveys with more constraining power may have to marginalize over this. We obtain scale-dependent constraints on the growth rate of structure in two bins, finding
$f\sigma _{8} = 0.55^{+0.16}_{-0.13},0.40^{+0.16}_{-0.17}$
in the ranges k = 0.007–0.055, 0.55–0.150 h Mpc−1. We also find consistent results using four bins. Assuming scale-independence we find a value
$f\sigma _{8} = 0.51^{+0.09}_{-0.08}$
, a ∼16 per cent measurement of the growth rate. Performing a consistency check of general relativity (GR) and combining our results with cosmic microwave background data only we find
$\gamma = 0.45^{+0.10}_{-0.11}$
, a remarkable constraint considering the small number of galaxies. All of our results are completely independent of the effects of galaxy bias, and fully consistent with the predictions of GR (scale-independent fσ8 and γ ≈ 0.55).
Abstract
We built a multiwavelength data set for galaxies from the Local Volume H i Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of 10 large galaxies for investigating ...properties in the galactic outskirts. The LVHIS sample covers nearly four orders of magnitude in stellar mass and two orders of magnitude in H i mass fraction (
$f_{\rm {H\,\small {I}}}$
). The radial distribution of H i gas with respect to the stellar disc is correlated with
$f_{\rm {H\,\small {I}}}$
but with a large scatter. We confirm the previously found correlations between the total H i mass and star formation rate (SFR), and between H i surface densities and SFR surface densities beyond R25. However, the former correlation becomes much weaker when the average surface densities rather than total mass or rate are considered, and the latter correlation also becomes much weaker when the effect of stellar mass is removed or controlled. Hence, the link between SFR and H i is intrinsically weak in these regions, consistent with what was found on kiloparsecs scales in the galactic inner regions. We find a strong correlation between the SFR surface density and the stellar mass surface density, which is consistent with the star formation models where the gas is in quasi-equilibrium with the mid-plane pressure. We find no evidence for H i warps to be linked with decreasing star-forming efficiencies.
We present the results of applying a percolation algorithm to the initial release of the Two Micron All Sky Survey Extended Source Catalog, using subsequently measured redshifts for almost all of the ...galaxies with K < 11.25 mag. This group catalog is based on the first near-IR all-sky flux-limited survey that is complete to 'b' = 5. We explore the dependence of the clustering on the length and velocity scales involved. The paper describes a group catalog, complete to a limiting redshift of 10 super(4) km s super(-1), created by maximizing the number of groups containing three or more members. A second catalog is also presented, created by requiring a minimum density contrast of dP/P . 80 to identify groups. We identify known nearby clusters in the catalogs and contrast the groups identified in the two catalogs. We examine and compare the properties of the determined groups and verify that the results are consistent with the UZC-SSRS2 and northern CfA redshift survey group catalogs. The all-sky nature of the catalog will allow the development of a flow-field model based on the density field inferred from the estimated cluster masses.
We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky (|b| > 10°). Its 136 304 spectra have yielded 110 256 new ...extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with (K, H, J, rF, bJ) ≤ (12.65, 12.95, 13.75, 15.60, 16.75). The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with z≤ 0.1, showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS.
We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from active galactic nuclei (AGNs) in their rest-frame UV spectra. We ...use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10 super(12) L sub(middot in circle) in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGNs can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.
2MTF – V. Cosmography, β, and the residual bulk flow Springob, Christopher M; Hong, Tao; Staveley-Smith, Lister ...
Monthly Notices of the Royal Astronomical Society,
02/2016, Volume:
456, Issue:
2
Journal Article
Peer reviewed
Open access
Using the Tully–Fisher relation, we derive peculiar velocities for the 2MASS Tully–Fisher survey and describe the velocity field of the nearby Universe. We use adaptive kernel smoothing to map the ...velocity field, and compare it to reconstructions based on the redshift space galaxy distributions of the 2MASS Redshift Survey (2MRS) and the IRAS Point Source Catalog Redshift Survey (PSCz). With a standard χ2 minimization fit to the models, we find that the PSCz model provides a better fit to the 2MTF velocity field data than does the 2MRS model, and provides a value of β in greater agreement with literature values. However, when we subtract away the monopole deviation in the velocity zero-point between data and model, the 2MRS model also produces a value of β in agreement with literature values. We also calculate the ‘residual bulk flow’: the component of the bulk flow not accounted for by the models. This is ∼250 km s−1 when performing the standard fit, but drops to ∼150 km s−1 for both models when the aforementioned monopole offset between data and models is removed. This smaller number is more in line with theoretical expectations, and suggests that the models largely account for the major structures in the nearby Universe responsible for the bulk velocity.
Using the 2MASS near-infrared photometry and high-signal-to-noise H i 21-cm data from the Arecibo, Green Bank, Nancay, and Parkes telescopes, we calculate the redshift-independent distances and ...peculiar velocities of 2018 bright inclined spiral galaxies over the whole sky. This project is part of the 2MASS Tully-Fisher survey (2MTF), aiming to map the galaxy peculiar velocity field within 100 h
−1 Mpc, with an all-sky coverage apart from Galactic latitudes |b| < 5°. A χ2 minimization method was adopted to analyse the Tully–Fisher peculiar velocity field in J, H, and K bands, using a Gaussian filter. We combine information from the three wavebands, to provide bulk flow measurements of 310.9 ± 33.9 , 280.8 ± 25.0, and 292.3 ± 27.8 km s−1 at depths of 20, 30, and 40 h
−1 Mpc, respectively. Each of these bulk flow vectors points in a direction similar to those found by previous measurements. At each of the three depths, the bulk flow magnitude is consistent with predictions made by the Λ cold dark matter (ΛCDM) model at the 1σ level. The maximum likelihood and minimum variance method were also used to analyse the 2MTF samples, giving similar results.
We present Hubble Space Telescope WFC3 F160W imaging and infrared spectral energy distributions for 12 extremely luminous, obscured active galactic nuclei (AGNs) at 1.8 < z < 2.7 selected via "hot, ...dust-obscured" mid-infrared colors. Their infrared luminosities span (2-15) × 1013 L , making them among the most luminous objects in the universe at z ∼ 2. In all cases, the infrared emission is consistent with arising at least for the most part from AGN activity. The AGN fractional luminosities are higher than those in either submillimeter galaxies or AGNs selected via other mid-infrared criteria. Adopting the G, M20, and A morphological parameters, together with traditional classification boundaries, infers that three-quarters of the sample are mergers. Our sample does not, however, show any correlation between the considered morphological parameters and either infrared luminosity or AGN fractional luminosity. Moreover, the asymmetries and effective radii of our sample are distributed identically to those of massive galaxies at z ∼ 2. We conclude that our sample is not preferentially associated with mergers, though a significant merger fraction is still plausible. Instead, we propose that our sample includes examples of the massive galaxy population at z ∼ 2 that harbor a briefly luminous, "flickering" AGN and in which the G and M20 values have been perturbed due to either the AGN and/or the earliest formation stages of a bulge in an inside-out manner. Furthermore, we find that the mass assembly of the central black holes in our sample leads the mass assembly of any bulge component. Finally, we speculate that our sample represents a small fraction of the immediate antecedents of compact star-forming galaxies at z ∼ 2.
We present new 21-cm neutral hydrogen (H i) observations of spiral galaxies for the 2MASS Tully-Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high ...signal-to-noise ratio H i spectra from which we extract 148 high-accuracy (<5 per cent error) velocity widths and derive reliable rotation velocities. The observed sample consists of 303 southern (δ < −40°) galaxies selected from the 2MASS Redshift Survey with K
s < 11.25 mag, cz < 10 000 km s−1 and axis ratio b/a < 0.5. The H i observations reported in this paper will be combined with new H i spectra from the Green Bank and Arecibo telescopes, together producing the most uniform Tully-Fisher survey ever constructed (in terms of sky coverage). In particular, due to its near-infrared selection, 2MTF will be significantly more complete at low Galactic latitude (|b| < 15°) and will provide a more reliable map of peculiar velocities in the local Universe.
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