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Are galaxies still evolving strongly? Christopher J. Miller

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The Effects of Environment. Hubble Heritage Image. On Galaxy Evolution at Low-z. Are galaxies still evolving strongly? Christopher J. Miller. Part I. Defining the questions, methods, and tools of the research topic. Physical Processes of Galaxies. Galaxy Interactions. - PowerPoint PPT Presentation
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Are galaxies still evolving strongly? Christopher J. Miller Hubble Heritage Image
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Page 1: Are galaxies still evolving strongly? Christopher J. Miller

Are galaxies still evolving strongly?

Christopher J. Miller

Hubble Heritage Image

Page 2: Are galaxies still evolving strongly? Christopher J. Miller

Part I

Defining the questions, methods, and tools of the research topic

Page 3: Are galaxies still evolving strongly? Christopher J. Miller

Physical Processes ofGalaxies

Page 4: Are galaxies still evolving strongly? Christopher J. Miller

Galaxy Interactions

• Few collisions, lots of interactions, but “horsehoes and handgrenades”

• ~ energy 108 -109 Supernovae• Quick, ~108 Years• Relatively rare (in recent times) 1-

5% maybe. Hard to measure.• Very, very hard to define

(observationally)• Field Galaxies undergo mergers

Hibbard

Hibbard and Barnes

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Page 5: Are galaxies still evolving strongly? Christopher J. Miller

Ram Pressure Stripping

• Galaxies fall (gravitationally) through the hot intracluster gas.

• 107 K, 10-4cm-3

• Hydrodynamic and Nbody simulations

• Mapping of gas content in Virgo spirals shows the HI disks to be highly disturbed, but the molecular content unchanged.

• Galaxies undergo ram pressure stripping when in the cores of clusters

• Slower than colliding galaxies

Vollner (Strasbourg)

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Page 6: Are galaxies still evolving strongly? Christopher J. Miller

Strangulation

• Halos are gradually (Gyrs) removed from disk galaxies

• Lack of fuel only changes the star-formation properties (not necessarily the morphologies)

Goto et al.

Page 7: Are galaxies still evolving strongly? Christopher J. Miller

Field

Cluster

Ram Pressure Stripping

StrangulationInteraction

White et al.

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Page 8: Are galaxies still evolving strongly? Christopher J. Miller

Galaxy Properties

Page 9: Are galaxies still evolving strongly? Christopher J. Miller

Star-Formation History

Bianchi et al., Condon et al., and others

Page 10: Are galaxies still evolving strongly? Christopher J. Miller

SFR Indicator

PRO CON

UV cont.Glow of young stars

Young stars, large z-range and evolution.

patchy extinction (0-3), IMF-- high stellar masses (>5). Population age dependent

H EWnebular lines re-emit the stellar luminosity

Coupling between nebular emission and SFR. Spatial mappings. Well-defined, easy to measure.

Instantaneous, massive SFR ((>10). Extinction (1). Assumes SF traced by ionized gas. IMF.

[OII] EWforbidden line

Good to high-z. Not strongly dependent on metal abundance. Easy to measure.

Excitation difference, not tied to ionizing luminosity. IMF. Extinction (0-2)

FIRabsorption by dust, re-emitted in IR.

Ideally the ultimate SFR indicator. SIRTF. Weak extinction.

Dust can also be heated by older stars (at 100um). Dependent on galaxy type. IMF.

RadioSynchrotron and free-free emission from HII

Sub-arc second resolution. Since from SN, trace young stars. Weak extinction. Tight FIR/Radio correlation

Connection between SF and synchrotron not well understood. IMF.

Page 11: Are galaxies still evolving strongly? Christopher J. Miller

Active Galactic Nuclei

vs.

Miller et al. 2003

Page 12: Are galaxies still evolving strongly? Christopher J. Miller

Morphology

Elliptical

E0 E6

S0 Sa Sb Sc

S0a SBa SBb SBc

Elliptical

Lenticular Spiral Spiral Spiral

BarredLenticular

Barred Spiral

BarredSpiral

BarredSpiral

Irregular

IrrFaulkes Telescope Project

Page 13: Are galaxies still evolving strongly? Christopher J. Miller

Bulge-to-Disk Ratio

Standard Bulge-to-Disk code takes ~2 minutes per galaxy (GIM2d).

Need to get to at least seconds per galaxy to do large datasets. Close……

Page 14: Are galaxies still evolving strongly? Christopher J. Miller

Concentration Index(poor man’s morphology)

Goto et al.

Page 15: Are galaxies still evolving strongly? Christopher J. Miller

Galaxy Environments

Page 16: Are galaxies still evolving strongly? Christopher J. Miller

Density Estimation

sdss.org

Page 17: Are galaxies still evolving strongly? Christopher J. Miller

Kernel vs. Nearest-NeighborDensity Estimation

• Fixed Kernel Width is well-studied in the mathematical literature.

• Higher-order bias• Use cross-validation

to find the “optimal” aperture.

• But still, does one aperture size suit all?

• Also well studied in the mathematical literature.

• Common in past astrophysical research

• Variable kernel size• low-order bias• Never converges to

the “truth”

Kernels

Nearest Neighbors

Page 18: Are galaxies still evolving strongly? Christopher J. Miller

Galaxy Clusters

• We use the SDSS-C4 galaxy cluster catalog

• >90% complete, <5% contamination for M>2x1014 solar

• Clusters identified and studied in the spectroscopic sample

• >250 clusters in ~1000 sq. degrees

Page 19: Are galaxies still evolving strongly? Christopher J. Miller

Summary: Part I

• Galaxy interactions, ram pressure stripping and strangulation affect the properties of galaxies.

• Such properties include star-formation rate, AGN activity, and morphology.

• By measuring the environment around every galaxy, we can try to isolate which of the above processes affect which of the above properties.

Page 20: Are galaxies still evolving strongly? Christopher J. Miller

Part II

What do we already know?

Page 21: Are galaxies still evolving strongly? Christopher J. Miller

Star-Formation vs. Environment

Gomez, Nichol, Miller et al.

Balogh, Eke, Miller et al.

Page 22: Are galaxies still evolving strongly? Christopher J. Miller

AGN fraction vs. Environment

Miller et al. 2003

Caution: Concentration Index is not a great morphology indicator (cannot separate E/S0’s for instance).

Page 23: Are galaxies still evolving strongly? Christopher J. Miller

Star-formation and Clusters:

Field

Miller et al. in prep.Gomez, Miller, Nichol et al.

Page 24: Are galaxies still evolving strongly? Christopher J. Miller

Part III:

A new research topic:

Phenomenological Studies of Brightest Cluster Galaxies

Page 25: Are galaxies still evolving strongly? Christopher J. Miller

Doing Research the “VO way”

• Start with an idea– E.g., galaxy properties as a function of

environment.– Brightest Cluster Galaxy properties and their local

environment

• Explore– What images and/or catalogs are available?

• Trial run– Start small

• Production mode– Grow with time and code to re-run on newer,

bigger, better data in the future.

Page 26: Are galaxies still evolving strongly? Christopher J. Miller

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Page 27: Are galaxies still evolving strongly? Christopher J. Miller

Inventory: What will we need?

• Data– Clusters (centers, masses, shapes, BCG)– Galaxy magnitudes, colors, shapes– Gas (X-ray) fluxes, extents

• Functions/Tools– Luminosity distances, absolute magnitudes, k-

corrections, angular diameters, statistical tools, plotting techniques, image display

• Services– Skynodes, Coneservices, SIAP services, Registry

Trial R

un

Page 28: Are galaxies still evolving strongly? Christopher J. Miller

The SDSS-C4 Cluster Catalogwww.ctio.noao.edu/~chrism/C4Miller et al. 2005, AJ, 130 968

Page 29: Are galaxies still evolving strongly? Christopher J. Miller

Get the SDSS Data

radius = zang(radius_fixed,c4data[I].z)/60.0 ; In arcminutes

siapcall,c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, $url=“http://casjobs.sdss.org/vo/DR4SIAP/SIAP.asmx/getSiapInfo?&FORMAT=image/jpeg” + $ “&BANDPASS=*&", root="images/sdss_c4_"+strtrim(string(c4data[I].cluster_id),2)

qry = " SELECT o.ra,o.dec, o.expAB_r, o.isoPhi_r " " FROM SDSSDR2:PhotoPrimary o " + $ " WHERE o.type = 3 AND o.petroMag_r < 23.0 " + $ " AND Region('Circle J2000 " + strtrim(string(c4data[I].ra_bcgphot,format='(f10.3)'),2) + $ " " + strtrim(string(c4data[I].dec_bcgphot, format='(f10.3)'),2) + $ " " + strtrim(string(radius, format='(f4.2)'),2) + "') ”

skyclient, qry=qry,str=sdss_gals

separ, sep, c4data[i].ra_bcgphot, sdss_gals.sdssdr2_ra, $ c4data[i].dec_bcgphot, sdss_gals.sdssdr2_dec

min = min(sep, minit)

Get the images

Get the catalog data

Page 30: Are galaxies still evolving strongly? Christopher J. Miller

Get the SDSS-2MASS Matches

qry = " SELECT o.ra,o.dec, o.modelMag_u, o.modelMagErr_u, o.modelMag_g,” + $ “ o.modelMagErr_g, o.modelMag_r, o.modelMagErr_r, o.modelMag_i, o.modelMagErr_i, “ + $ “o.modelMag_z, o.modelMagErr_z, o.extinction_u, o.extinction_g, o.extinction_r, “ + $ “o.extinction_i, o.extinction_z, t.j_m, t.k_m, t.h_m, t.j_msigcom, t.k_msigcom, t.h_msigcom " + $ " FROM SDSSDR2:PhotoPrimary o, TWOMASS:PhotoPrimary t " + $ " WHERE XMATCH(o,t)<" + strtrim(string(chisq),2) + " " + " AND o.type = 3 " + $ " AND Region('Circle J2000 " + strtrim(string(c4data[I].ra_bcgphot,format='(f10.3)'),2) + $ ” " + strtrim(string(c4data[I].dec_bcgphot, format='(f10.3)'),2) + $ " " + strtrim(string(radius, format='(f4.2)'),2) + "') "

skyclient,qry=qry,str=sdss_2mass_gals

Get the 2MASS-SDSS cross matches

Page 31: Are galaxies still evolving strongly? Christopher J. Miller

Get the X-ray data

conecall, c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, str=str, $ url = "http://heasarc.gsfc.nasa.gov/cgi-bin/vo/cone/coneGet.pl?table=wgacat&r"

conecall, c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, str=str, $ url = http://heasarc.gsfc.nasa.gov/cgi-bin/vo/cone/coneGet.pl?table=xmmssc& sizeit = size(str);If there is XMM-SSC data, get the image IF (sizeit[1] gt 1) THEN BEGIN separ, separ, c4data[i].ra_bcgphot, str.ra, c4data[i].dec_bcgphot, str.dec min = min(separ, minit) bcg_EP[I] = str[minit].ep_flux IF not (keyword_set(nosiap)) THEN siapcall,c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, 0.1, $ url="http://xsa.vilspa.esa.es:8080/aio/jsp/siap.jsp", $ root="images/xmm_bcg_c4_"+strtrim(string(c4data[I].cluster_id),2), /metadata,str=str ENDIF

Get the WGACAT sources

If a WGACAT source exists, get the PSPC image

Page 32: Are galaxies still evolving strongly? Christopher J. Miller

Calculate the Absolute Magnitudeskcorrect,mags, magerrs, zs , kcorr, filterlist=filterlist, band_shift=0.0

bcg_absJ[I] = sdss_2mass_gals[minit].twomass_j_m - kcorr[5,minit] (5*alog10(lumdist(c4data[I].z)*1e6) + 5)

mR = MQ + DM(z) + KQR(z),

where mR is the apparent magnitudeMQ is the absolute magnitudeDM(z) is the distance modulus, accounting angular diameter distance and cosmological surface-brightness dimmingKQR(z) is the K-correction.

See: http://cosmo.nyu.edu/blanton/kcorrect/v3_2-index.htmlSee: Hogg et al. (2002)

Page 33: Are galaxies still evolving strongly? Christopher J. Miller

plot, -(bcg_isophi[wkeep]-90),c4data[wkeep].ang1000, psym=4, $ xtitle="BCG Position Angle (degrees)", $ ytitle="C4 Cluster Position Angle (within 1Mpc) (degrees)"

h = histogram(abs(-(bcg_isophi[w]-90)-c4data[w].ang1000),omin=omin, binsize = 5)plot, 5*findgen(n_elements(h)) + omin, h, psym=10

kstwo, delta_phi, zran,d,prob

result = r_correlate(-(bcg_isophi[w]-90), c4data[w].ang1000)

Finally: AnalyzeMake Plots

Look for correlations

Make Histograms

Run statistical tests

Look at th

e BCGs

Page 34: Are galaxies still evolving strongly? Christopher J. Miller

Example High Density BCGs

Page 35: Are galaxies still evolving strongly? Christopher J. Miller

Example Low Density BCGs

Page 36: Are galaxies still evolving strongly? Christopher J. Miller

X-ray BCGsPSPC SDSS RASS

Page 37: Are galaxies still evolving strongly? Christopher J. Miller

Results Part 1:

• Statistical tests indicate a ~2 result that the BCG PA is aligned with the cluster PA.

• BCG ellipticity shows no significant dependence on local density

• BCG colors are 2 tenths bluer in the density regions.

• BCGs luminosity shows no significant dependence on local density

Page 38: Are galaxies still evolving strongly? Christopher J. Miller

Results Part 2:

• X-ray detected clusters favor the BCGs in the highest density regions.

• Indicates a possible bias in BCG cluster studies.

Page 39: Are galaxies still evolving strongly? Christopher J. Miller

Understanding BCG Evolution

• Lin and Mohr (2005) find evidence that BCGs grow over time and are more massive in the more massive clusters.

• Andernach et al. (2006) find BCG ellipticity decreases with cluster mass

• Harris et al. (2006) use ACS/WFC to discover strong color gradients in BCGs (old red star clusters live in the centers).

• Brough et al. find that X-ray the brightest luminous clusters have BCGs with shallow light profiles (more collisions).

• All of the above are consistent with bottom up hierarchical growth and inconsistent with top-downSee also Laine et al. (2003)

• Haruyoshi et al. (2003) find that BCG luminosities not correlated with the underlying viral density

• Collins et al. (2003) find that BCGs in high Lx clusters show no mass growth.

• Egami et al. (2006) suggest BCGs are star-forming (IR)

• Nelson et al. (2002) find that BCG sizes using NICMOS are the same size at z>0.5 as they are z=0. They find smaller radii at z=0.5 with WFPC2.

• All of the above are consistent with monolithic collapse.

Page 40: Are galaxies still evolving strongly? Christopher J. Miller

Our New Conclusions• Given a starting point (re: Inventory and plan, tools), we can

easily do and re-do research without having the majority of the data on our hard disks.

• In this case, we collected SDSS optical, 2MASS infrared, and X-ray images and catalog data for a sample of 300 BCGs in the SDS C4 cluster catalog

• We found (weak) evidence that the position angle of the BCG is aligned with the PA of the cluster.

• We find a small fraction 5-10% of our BCGs have very high local densities.

• We find a significant trend in bluer BCGs having higher local densities.

• Hypothesis: these are younger BCGs in younger systems, still under-going collapse.

• More questions to answer.


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