Depto. de Astronomía (UGto)
Download
1 / 30

Astronomía Extragaláctica y Cosmología Observacional - PowerPoint PPT Presentation


  • 96 Views
  • Uploaded on

Depto. de Astronomía (UGto). Astronomía Extragaláctica y Cosmología Observacional. Lecture 9 Groups and Clusters of Galaxies – I (Galaxies). Definition – Richness Catalogs rich clusters groups compact groups pairs Morphology and Classification Radial Profiles Substructuring

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Astronomía Extragaláctica y Cosmología Observacional' - cassandra-brady


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Depto. de Astronomía (UGto)

Astronomía Extragaláctica y Cosmología Observacional

Lecture 9

Groups and Clusters of Galaxies – I (Galaxies)

  • Definition – Richness

  • Catalogs

    • rich clusters

    • groups

    • compact groups

    • pairs

      Morphology and Classification

      Radial Profiles

      Substructuring

      Environmental Effects and Segregation

    • cDs

    • morphological segregation (morphology-density relation)

    • Red Sequence and Butcher-Oemler effect

    • ram pressure and galaxy harassment


Pair → 2 galaxies (~ 1012 M)

Group → ~ 10 galaxies (~ 1012-1013 M)

Poor Cluster → ~ 100 galaxies (~ 1013-1014 M)

Rich Cluster → ~ 1 000 galaxies (~ 1014-1015 M)

Supercluster→ ~ 10 000 galaxies (~ 1015-1016 M)

Hercules/A2151 (Cl)

Stephan Quintet (CGr)

M51 (GPair)


Interacting Galaxies

[Arp & Madore 1982, JRASC 76, 315

Toomre & Toomre 1972, ApJ 178, 623 ]

Dumbbell

[Matthews et al. 1964, ApJ 140, 35 ]

Wirth et al. 1982, AJ 87, 602,

Gregory et al. 1994, A&A 106, 1]

[Alonso et al. 2005, MNRAS 375, 1017]


  • 1958 – G. Abell [ApJS 3, 211]: first systematic search (by visual inspection) for rich clusters

    • Palomar Observatory Sky Survey (POSS, Schmidt 1.2m, δ > 27°, |b|  30°, 879 pairs of plates)

      • blue band → 103a-O emulsion, mO,lim = 21.1

      • red band →103a-E emulsion, mE,lim= 20.0

    • criteria:

      • richness→Ngal  50 galaxies, between m3 and m3+2 mag (local sky subtraction)

      • compactness→ r < RA = 1.5 h-1 Mpc = (1.72/zest) arcmin zest = f(m10)

      • distance→0.02 (plate size limit) < z < 0.2 (mag limit  m3 ≤ 17.5)

    • Ncl = 2712 (statistical sample: Ncl= 1682)

  • 1989 – Abell, Corwin & Olowin [ACO, ApJS 70, 1]: extension to southern celestial hemisphere

    • ESO/SERC Southern Sky Survey [UK Schmidt 1.2m (AAO) + ESO Schmidt 1.0m (La Silla),

      δ < 17°, |b|  30°, 606 pairs of plates]

      • blue band → IIIa-J emulsion + GG395 filter, mJ,lim = 22.5

      • red band → IIIa-F emulsion + RG610 filter, mF,lim= 21.5

    • same criteria (except for a “universal” sky subtractions, based on a field LF)

    • Ncl = 1361 (rich) + 1174(supplementary – less rich, R = 0, or D > 6)


[ACO 1989, ApJS 70, 1]

Field LF

z = f(m10)

Zone of Avoidance


Richness Classes (R )

0 30 – 49

1 50 – 79

2 80 – 129

3 130 – 199

4 200 – 300

5 300 or more

R (Ngal)

Distance Classes (D)

1 13.3 – 14.0 0.0283

2 14.1 – 14.8 0.0400

3 14.9 – 15.6 0.0577

4 15.7 – 16.4 0.0787

5 16.5 – 17.2 0.1310

6 17.3 – 18.0 0.1980

D (range of m10) (mean zest)

Limitations: - projection effects [incompleteness (?) and contamination (about 10%)]

- Scott (1957) effect: R increases with zest


Abell

ACO

Ncl = 4073

Complete to z ~ 0.2 (zmax ~ 0.4)

n(R  1) = 10-5h3 Mpc-3  <r> ~ 50 h-1 Mpc


  • 1961-1968 – Zwicky et al. [Catalogue of Galaxies and Clusters of Galaxies]:

    • POSS

    • criteria:

      • richness→Ngal  50 galaxies, between m1 and m1+3 mag

      • density → isopleth: ngal > 2 nfield

    • Ncl = 9134

  • 1985 – Shectman [ApJS 57, 77]: based on

  • Shane & Wirtanen [1954] counts

    • Lick Galaxy Survey (b  40°, δ  -22.5°)

    • Ncl = 646


  • 1992 – Lumsden et al. [MNRAS 258, 1]: Edinburgh-Durham Cluster Catalog (EDCC)

    • COSMOS (Coordinates and Magnitudes Object Survey) machine

    • Ncl = 737

  • 1997 – Dalton et al. [MNRAS 289, 263]:

  • APM Cluster Catalogue (APMCC)

    • APM (Automatic Plate Measuring)

      machine

    • Ncl = 937


  • 2003 – Gal et al. [AJ 125, 2064]: Northern Sky Optical Cluster Survey (NoSOCS)

    • POSS-2 (2nd Epoch) – DPOSS (digitized at STScI – PDS)

    • SExtractor, photometric redshifts

    • Ncl = 8155


NoSOCS

AqrCC

EDCC

APMCC

ACO Supl.


Compact:

  • Loose:

  • usually detected by

    percolation analysis

  • Ngal 3 (or 5)

  • 1982 – Hickson [ApJ 255, 382]: the most

  • known catalog of compact groups (HCG)

    • criteria:

      • richness→ Ngal 4, in a magnitude range ≤ 3 mag

      • concentration → <Σgal> ≤ 26 μR

      • isolation → no galaxy with m < m1+3 inside 3Rcg

    • Ncg = 100

(1948)

(1877)


  • Are compact groups real bound systems?

  • they contain more spirals than expected from the usual morphology-density relation

  • they have very short predicted lifetimes against merging

  • the number of “members” with discordant redshifts is very high (~ 1/3)

Stephan Quintet (CGr)


Catalog Ngr zlim mlim Area Ref.

  • Hickson 100 POSSI Hickson et al. 1989

  • SCG 59 COSMOS Prandoni et al. 1994

  • P-PS 188 0.05 B ≤ 15.5 P-P Trasarti-Battistoni et al. 1998

  • WBL 732 0.03 mph≤ 15.7 POSSI White et al. 1999

  • UZC-SSRS 1 168 0.04 B ≤ 15.5 4.7 sr Ramella et al. 2002

  • ESP 231 0.16 bJ≤ 19.4 0.01 sr Ramella et al. 1999

  • LCRS 1 495 0.15 R ≤ 17.5 0.21 sr Tucker et al. 2000

  • 2PIGG (2dFGRS) 12 566 0.20 bJ≤ 19.5 0.61 sr Eke et al. 2004

  • C4CC (SDSS-DR2) 748 0.17 r ≤ 17.7 1.01 sr Miller et al. 2005

  • 2MGrC (2MASS) ~ 1 500 0.05 Ks ≤ 11.3 all-sky Crook et al. 2007

  • Abell/ACO 4 073 0.20 mph≤ 20.0~8.2 sr Abell 1958, ACO 1989

  • EDCC 737 0.19 bJ≤ 20.5 0.5 sr Lumsden et al. 1992

  • APMCC 937 0.13 bJ≤ 20.5 1.31 sr Dalton et al. 1997

  • NoSOCs 16 546 0.25 rF≤ 19.5 3.35 sr Gal et al. 2008


  • Criteria:

  • richness (Abell R )

  • shape of the galaxy distribution (Abell)

  • concentration (Zwicky)

  • distribution of the brightest members (10, RS)

  • presence or absence of a cD galaxy (BM)

  • morphology of the dominant galaxy (BM)

  • subclustering

  • galaxy content...

  • Bautz & Morgan:

  • I → central cD galaxy

  • II → intermediate E/cD

  • III → no dominant galaxy

  • also intermediate types

    I-II and II-III

Rood & Sastry:

  • Abell:

  • regular

  • irregular

  • Zwicky:

  • compact

  • semi-compact

  • open

  • cD → single dominant cD

  • B → dominant binary

  • L → linear array of galaxies

  • C → single core of galaxies

  • F → flattened distribution

  • I → irregular distribution



[Geller & Beers 1982, PASP 94, 421]


  • Many models have been proposed in order to describe the radial distribution of galaxies in a

    cluster, the classical ones been the Hubble profile and the de Vaucouleurs profile

    (originally proposed for ellipticals)

    1962 – I. King [AJ 71, 64]: proposed a radial profile (for globular clusters) derived from

  • solutions of the Fokker-Planck equation (isothermal sphere),

  • that fits quite well the distribution of galaxies in a cluster:

  • Σ(r) = Σ0 [1 + (r/Rc)2]-γ(in 2D)

  • n(r) = n0 [1 + (r/Rc)2]-3γ/2 (in 3D)

  • where Σ0 and n0 are the central projected and spatial

  • densities, related by

  • Σ0 = 2 Rc n0

  • Rc is the core radius (usually in the range

  • 0.1–0.25 h-1 Mpc), and γ is the slope for r > Rc,

  • originally γ = 1 (slightly smaller values are found

  • for galaxy clusters)

  • Other proposed models are models without a core, like

    the Hernquist [1990, ApJ 356, 359] and Navarro, Frenk

    & White [1997, ApJ 490, 493] (that fits well the

    distribution of DM, for which it was constructed)


  • There are many methods for detecting substructures

    (merging groups?) in a cluster

  • 1-D (redshift space)

    • deviations from Gaussianity (skewness and kurtosis)

  • 2-D (projection)

    • surface number density contour maps (isodensity)

      [Geller & Beers 1982, PASP 94, 421]

    • symmetry test (β) (and others)

      [West et al. 1988, ApJ 327, 1]

    • multiscale analysis (wavelets)

      [Girardi et al. 1997, ApJ 482, 41]

  • 3-D

    • δ-test (local  global kinematics)

      [Dressler & Shectman 1988, AJ 95, 985]

    • surface photometry test

      [West & Bothum 1990, ApJ 350, 36]

    • ε-statistics (mass)

      [Bird 1993, AJ 107, 1637]

    • κ-test (modified δ-test)

      [Colless & Dunn 1996, ApJ 458, 435]

[Bravo-Alfaro et al. 2008]


A2521

isoplets

radial profile

gals w/ z (in the cluster)

A2595


A3985

A2565-B

gals w/ z

(foreground)

(background)


Effects from clusters to galaxies Effects from galaxies to clusters

dominant galaxy ICM metal enrichment

morphological segregation ICM warming

gas loss (by ram pressure) relativistic particles injection

Butcher-Oemler effect

merging (by dynamical friction)


  • Dominant galaxy:

  • galaxies brighter than normal galaxies (MV ≈ -24), with a narrow dispersion (0.3 – 0.35 mag)

  • rest at (or close to) the centre of rich clusters (there are no cDs where s ≤ 1 gal Mpc-3)

  • present an extended stellar envelope (is it part of the galaxy or of the cluster?)

  • most of them present double nucleus (25 – 50%)

  • are usually flat and aligned to the galaxy distribution in the cluster (or to neighbor clusters)

  • they do not follow the luminosity function of the other cluster galaxies


  • Proposed formation scenarios:

  • merger of bright galaxies or accretion of small ones by dynamical friction (galactic cannibalism)

    [Ostrike & Tremaine 1975, Dubinski 1998], but high   large times, also peculiar velocities

  • accumulation of loose stars that fall in the

    cluster potential, taken off galaxies by tidal

    effects[Merritt 1984], but colors and metallicities …

  • accumulation of gas in the cluster potential by

    cooling flows[Mushotzky et al. 1981], but not observed …

  • formation in groups [Merritt 1985, Coziol et al 2008]

  • primordial formation (before clusters), but how?

A496 Cluster cD

Hydra Cluster cD

Perseus Cluster cD


  • Morphological segregation:

  • rich and regular clusters present a high fraction of early-type galaxies (E and S0),

    and a strong radial gradient of this fraction (higher in the centre)

  • poor and irregular clusters and groups present a high fraction of S, and have small

    or no gradient of morphological types

Morphology-density relation with z:

[Dressler 1980, ApJ 236, 351]

[Dressler el al. 1997, ApJ 490, 577]

[Smith et al. 2005, ApJ 620, 78]


  • Red Sequence:

  • Color-Magnitude Diagram (CMD): red galaxies form

    a well defined sequence (called “red sequence”)

  • mostly early type (E and S0) with more evolved/older

    stellar populations (limit for evolution)

  • the slope driven by the mass-metallicity relation

[see López-Cruz et al. 2004, ApJ 614, 679]


[Butcher & Oemler 1984, ApJ 285, 426]

  • Butcher-Oemler effect:

  • there is an excess of blue galaxies in clusters at high redshifts when compared to local clusters


fraction of clusters of 1015M formed

  • Recent evolution:

  • rich clusters formed recently (z < 2)

  • there is considerable evolution of galaxies

    in clusters in the recent past (z < 0.5)

  • have galaxies evolved mostly in clusters/groups?

[Richstone, Loeb & Turner 1992, ApJ 393, 477]


  • Ram pressure of gas:

  • the pressure of the IC hot gas is higher than the pressure of the HI in the S galaxies

  • so, S can loose HI by ram pressure of the IC gas

[Bravo-Alfaro et al. 2000,

AJ 119, 580]


  • Papers:

  • Bautz & Morgan 1970, ApJ 162, L149

  • Rood & Sastry 1971, PASP 83, 313

  • Ostriker & Tremaine 1975, ApJ 202, L113

  • Mushotzky et al. 1981, ApJ 244, L47

  • Hickson 1982, ApJ 255, 382

  • Merritt 1984, ApJ 276, 26

  • Merritt 1985, ApJ 289, 18

  • Prandoni, Iovino & MacGillivray 1994, AJ 107, 1235

  • Trasarti-Battistoni 1998, A&AS 130, 341

  • White et al. 1999, AJ 118, 2014

  • Ramella et al. 1999, A&A 342, 1

  • Tucker et al. 2000, ApJS 130, 237

  • Ramella et al. 2002, AJ 123, 2976

  • Eke et al. 2004, MNRAS 348, 866

  • Miller et al. 2005, AJ 130, 968

  • Crook et al. 2007, ApJ 655, 790

  • Coziol et al. 2008, submitted to AJ

  • Bravo-Alfaro et al. 2008, in preparation


ad