The Long-Term Variability of the X-Ray Sources in NGC 6946 and NGC 44854490

a r X i v :0804.1411v 2 [a s t r o -p h ] 14 J u l 2008

ApJS,in press

Preprint typeset using L A T E X style emulateapj v.10/09/06

THE LONG-TERM VARIABILITY OF THE X-RAY SOURCES IN NGC 6946AND NGC 4485/4490

Joel K.Fridriksson 1,2,Jeroen Homan 2,Walter H.G.Lewin 1,2,Albert K.H.Kong 3,and David Pooley 4

ApJS,in press

ABSTRACT

We analyze data from ?ve Chandra observations of the spiral galaxy NGC 6946and from three Chandra observations of the irregular/spiral interacting galaxy pair NGC 4485/4490,with an emphasis on investigating the long-term variability exhibited by the source populations.We detect 90point sources coincident with NGC 6946down to luminosities of a few times 1036ergs s ?1,and 38sources coincident with NGC 4485/90down to a luminosity of ～1×1037ergs s ?1.Twenty-?ve (15)sources in NGC 6946(NGC 4485/90)exhibit long-term (i.e.,weeks to years)variability in luminosity;11(4)are transient candidates.The single ultraluminous X-ray source (ULX)in NGC 6946and all but one of the eight ULXs in NGC 4485/90exhibit long-term ?ux variability.Two of the ULXs in NGC 4485/90have not been identi?ed before as ultraluminous sources.The widespread variability in both systems is indicative of the populations being dominated by X-ray binaries,and this is supported by the X-ray colors of the sources.The distribution of colors among the sources indicates a large fraction of high-mass X-ray binaries in both systems.The shapes of the X-ray luminosity functions of the galaxies do not change signi?cantly between observations and can be described by power laws with cumulative slopes ～0.6?0.7(NGC 6946)and ～0.4(NGC 4485/90).

Subject headings:galaxies:individual (NGC 6946,NGC 4485,NGC 4490)—X-rays:binaries —

X-rays:galaxies

1.INTRODUCTION

The systematic study of X-ray source populations in external galaxies ?rst became possible with the Einstein Observatory in 1978.Signi?cant advances in the ?eld were made with subsequent satellites such as ROSAT ,but a giant leap forward has been taken with Chan-dra .With its subarcsecond spatial resolution and high sensitivity it is possible to resolve the vast majority of the luminous ( 1037ergs s ?1)X-ray sources in galaxies out to distances of 20?30Mpc.In addition,the spec-trometric capabilities of the Chandra ACIS CCD detec-tor allow spectral properties of sources to be extracted.For two recent reviews of the study of X-ray sources in normal galaxies,emphasizing results from Chandra ,see Fabbiano &White (2006)and Fabbiano (2006).We now know that X-ray source populations in galaxies are dominated at high luminosities ( 1037ergs s ?1,the range typically explored with Chandra observations)by X-ray binaries (XRBs)consisting of an accreting neutron star or black hole and a stellar companion.In addition,galaxies usually have a few young supernova remnants (SNRs)in this luminosity range.Unsurprisingly,the X-ray populations in early-type galaxies (E and S0)seem to consist mostly of low-mass X-ray binaries (LMXBs),whereas galaxies with younger stellar populations (spi-ral and irregular galaxies)typically have a much higher fraction of the shorter lived high-mass X-ray binaries (HMXBs).In galaxies with a high star formation rate HMXBs are especially common.

1

Department of Physics,Massachusetts Institute of Technology,Cambridge,MA 02139;joelkf@https://www.doczj.com/doc/594645858.html,.

2MIT Kavli Institute for Astrophysics and Space Research,Cambridge,MA 02139.

3Institute of Astronomy and Department of Physics,National Tsing Hua University,Hsinchu,Taiwan 30013.

4Department of Astronomy,University of Wisconsin–Madison,Madison,WI 53706.

An important class of sources in external galaxies are the so-called ultraluminous X-ray sources (ULXs),usu-ally de?ned as non-nuclear sources with implied isotropic X-ray luminosities ≥1039ergs s ?1.Detections of ULXs with luminosities as high as ～1041ergs s ?1have been reported (see,e.g.,Davis &Mushotzky 2004).The na-ture of ULXs is still debated,and it has been argued that at least some of them might be a new class of objects,so-called intermediate-mass black holes (IMBHs)with masses M ～102?104M ⊙(see,e.g.,Miller &Colbert 2004).

We present in this paper the X-ray source population study of the spiral galaxy NGC 6946and the interact-ing irregular/spiral system NGC 4485/4490.A special emphasis is placed on studying the long-term (weeks to years)variability properties of the source populations.These galaxies were chosen because they are nearby (D 8Mpc)and have multiple (three or more)long ( 20ks)Chandra ACIS exposures spanning a baseline of a few years.Both show an enhanced star formation rate.The spiral NGC 6946also has the fortunate char-acteristic of being observed nearly face-on,and the NGC 4485/90system has low Galactic extinction and a large number of ULXs.For more background information on the galaxies,see §§3.1and 3.2.

Not much work has been done on the long-term vari-ability of X-ray sources in external galaxies,since Chan-dra observations at multiple epochs are usually not avail-able.We know from observations in our own Galaxy that time variability of various kinds,including tran-sient outbursts,eclipses,dips,as well as less severe vari-ations in ?ux,is very common among XRBs.Temporal and spectral analysis carried out for the most luminous sources in nearby galaxies shows behavior similar to that in Galactic XRBs,clearly pointing to XRB populations (see Fabbiano 2006,and references therein).For ex-ample,Kong et al.(2002)?nd that among 204detected

2Fridriksson et al.

sources in M31,50%are variable on timescales of months and 13are transients.Sivako?et al.(2005b)?nd short-timescale ?ares in 3out of 157sources in the elliptical galaxy NGC 4697,and

two

of

the

?ares have durations and luminosities similar to Galactic superbursts (ther-monuclear bursts with very long (hours)durations and very large ?uences;see Kuulkers 2004).Sivako?et al.(2005a)also ?nd long-term variability in 26out of 124sources in NGC 4697,and 11of those are transient candidates.Zezas et al.(2006),analyzing seven Chan-dra observations of the Antennae galaxies,?nd intensity and/or spectral variability among sources on timescales of years,months,days,and hours.Overall,～50%of the sources detected in each observation show either spec-tral or intensity variation but do not all follow a com-mon trend,indicating that there are various classes of sources.Of the 14ULXs in the Antennae,12show long-term variability.In general,variability of some sort is very common among ULXs (see Fabbiano &White 2006;Fabbiano 2006).Despite widespread variability in lumi-nosity among individual sources,X-ray luminosity func-tions (XLFs)seem to be remarkably stable from one observation to another,as indicated by observations of NGC 5128(Kraft et al.2001),M33(Grimm et al.2005),and the Antennae (Zezas et al.2007).

The organization of the paper is as follows.In §2we describe the common analysis steps performed for both galaxies,including source detection,photometry,the construction of light curves and hardness ratios,and testing for ?ux and spectral variability.In §3we discuss general properties and the observations of the galaxies and present the results of the source detection.In §4we present and discuss our results on various properties of the source populations in the galaxies.Finally,in §5we brie?y summarize our results.Included are tables with the source catalog for each galaxy and various observed and derived parameters for each source.

2.DATA ANALYSIS

The Chandra observations of both galaxies were an-alyzed with the CIAO software,version 3.4(CALDB ver. 3.3.0),and with ACIS Extract (hereafter AE),version 3.131.AE is an ACIS point source extrac-tion package developed at Pennsylvania State Univer-sity (Broos et al.2002),which assists in a large vari-ety of complex data processing tasks.The procedures used in AE are described in Townsley et al.(2003)and Getman et al.(2005).We note that all errors mentioned in this paper are,unless explicitly stated otherwise,Pois-son errors with a con?dence level corresponding to 1σGaussian.They were computed using the Gehrels ap-proximation of Poisson limits (Gehrels 1986).

2.1.Source detection

The level 1event ?les from the Chandra data archive were reprocessed,and new level 2event ?les created by following the standard ACIS data preparation procedure recommended by the Chandra X-ray Center (CXC).5The data were checked for periods of unusually high back-ground.No such periods were found in any observation of either galaxy.A monochromatic exposure map eval-uated at 1.5keV was created for each observation,and

5

See https://www.doczj.com/doc/594645858.html,/ciao/guides/acis

2,2,2

√

2,

8,8

√

manual/index.html .

X-Ray Variability in NGC6946,NGC4485/903 the centroid of the extraction regions as recommended in

Broos et al.(2002).

2.2.Light Curves

AE is capable of performing extensive broadband pho-

tometry.For all sources an estimate of both the photon

?ux and the energy?ux in the0.3?7keV band was com-

puted from the AE results for each observation,as well

as for the co-added exposure.For all but the faintest

sources the photon?ux was computed by dividing the

number of net(i.e.,background-subtracted)counts by

the exposure time and the mean e?ective area at the

source location for a given energy band(the MEAN

,(1)

T

and the hard color as

H?M

HR2=

4Fridriksson et al.

to our using 7keV.However,for the vast majority of sources only a very small fraction of the counts in the 0.3?8keV band is between 7and 8keV,so this should have a negligible e?ect.They also use a slightly di?er-ent method to account for variations in e?ective area.As Prestwich et al.(2003)discuss in their paper,absorption will tend to blur the distinction in a color-color diagram between the di?erent source types.However,this e?ect should not be very severe for the galaxies studied in this paper;although NGC 6946su?ers from substantial ex-tinction,it is observed face-on,and the absorption col-umn in the direction of NGC 4485/90is low (see §3).2.4.Variability

We compute a signi?cance parameter for long-term ?ux variability for each source:

S ?ux =max i,j

|F i ?F j |

σ2F i +σ2F j ,(3)where F i denotes the photon ?ux of a source in the

i th Chandra observation,and σF i is the correspond-ing error.We de?ne a source as variable if S ?ux >3.We also quantify the variability by computing the ratio R =F max /F min .We consider a source to be a tran-sient candidate if its measured ?ux is consistent with zero (within ～1σerror)in at least one observation,and if the source is also clearly variable (S ?ux >3).

We test for short-term ?ux variability (within single observations)by performing a one-sided Kolmogorov-Smirnov test for each source in each observation,compar-ing event times to a uniform count-rate model.We de?ne a source as showing evidence for variability if the signi?-cance of the computed K-S statistic is less than 3×10?3(i.e.,if the null hypothesis that the count rate is uniform can be rejected at the 99.7%level or more,corresponding to approximately 3σGaussian con?dence).

To search for long-term spectral variability,we com-pute signi?cance parameters for the variability in the hardness ratios.They are de?ned analogously to the ?ux variability parameter above.Again,we require 3σcon?dence to classify a source as variable.

2.5.ROSAT and XMM-Newton Data

Apart from Chandra ,there are three other X-ray tele-scopes that have had good enough spatial resolution to possibly be of signi?cant value to this study.The Ein-stein HRI,the ROSAT HRI,and the XMM-Newton EPIC cameras all had or have an on-axis resolution of 10′′.However,the Einstein and ROSAT HRIs were only sen-sitive in the 0.15?3.5and 0.1?2.4keV bands and had negligible energy resolution.None of the galaxies ana-lyzed in this paper was observed with the Einstein HRI.For the ULXs that were well resolved from neighbor-ing bright sources the long-term light curves were ex-tended by adding data points from ROSAT and XMM-Newton observations.It was usually necessary to use small extraction regions to minimize the contamination from nearby sources and from the di?use emission in which many sources are embedded.

2.5.1.ROSAT

ROSAT count rates were derived from the RDF (ra-tionalized data format)?les available from the ROSAT

TABLE 2

ROSAT HRI Observations of NGC

6946Start Date Seq.ID Exp.a (ks)

1994May 14rh600501n0059.891995Aug 13rh600718n0021.511996Aug 10

rh500476n00

8.36

a Good live exposure time.

Archive.The event data ?les were corrected for the HRI aspect error (see,e.g.,David et al.1999)using the cor-rection script developed at the Smithsonian Astrophys-ical Observatory (SAO).8Background-subtracted count rates were extracted using the ASTERIX software pack-age (ver. 2.3-b2).The xrtsort ,xrtsub ,and xrtcorr tasks were used,which automatically make dead-time,vignetting,and quantum e?ciency corrections.In all cases counts were extracted from a circle of radius 8′′.For point sources with an o?-axis angle 5′the PSF encircled energy fraction for such a circle is ～0.84(David et al.1999;Zimmermann et al.1998).The count rates were therefore divided by this number to correct for the counts missed by the ?nite extraction region.

To facilitate comparison with the Chandra results count rates from ROSAT were converted to energy ?ux in the 0.3?7keV band using PIMMS.To determine the spectral model to use for the conversion the eight mod-els described in §2.2were ?tted to the source spectrum from the co-added Chandra exposure,and the best-?tting model used.

2.5.2.XMM-Newton

For XMM-Newton data a new analysis was performed for each of three EPIC detectors using the SAS software,versions 7.0.0and 7.1.0,and the latest available cali-bration ?les at the time of the analysis.Starting with the original data ?les (ODFs)from the XMM-Newton archive,MOS and PN data were reprocessed using the emproc and epproc tasks.After excluding periods of high background,source spectra were extracted with the evselect task.The eregionanalyse task was used to center the extraction radius on the centroid of the counts distribution for each source.Counts were extracted from circles with radii in the range 8′′to 15′′as deemed ap-propriate in each case.The event selection criteria used for the spectral extraction were PATTERN =0?12and FLAG =#XMMEA

X-Ray Variability in NGC6946,NGC4485/90

5

Fig. 1.—DSS images of NGC6946(left)and NGC4485/4490(right)with positions of detected X-ray sources overlaid.Foreground stars are represented with plus symbols,historical supernovae with boxes,SNRs with diamonds,ULXs with crosses,and other sources with circles.Blue indicates that long-term variability is detected,green that it is not,and red denotes transient candidates.The white ellipses are the D25elliptical isophotes and the yellow circle encloses the central area in NGC6946that was excluded from analysis.

?uxes for the three instruments were combined into a single?ux result by taking the mean weighted with the inverse variance(i.e.,squared error)of each individual ?ux.

3.OBSERVATIONS AND SOURCE DETECTIONS

3.1.NGC6946

NGC6946is one of the closest large spiral galax-ies and is seen nearly face-on.It is classi?ed by de Vaucouleurs et al.(1991)as type SAB(rs)cd.It has been extensively studied in almost all wavelength bands and has been shown to have strong nuclear starburst activity(Elmegreen et al.1998b).High star formation activity in its disk has also been observed(Sauty et al. 1998),and in agreement with this NGC6946has been host to nine recorded supernovae in the last91years (three in the past7years),currently the highest known number of historical supernovae in any galaxy.The global star formation rate in NGC6946for stars in the mass range2?60M⊙is estimated by Sauty et al. (1998)to be～4M⊙yr?1,and Crosthwaite&Turner (2007)estimate the dynamical mass of the galaxy to be ～2×1011M⊙.

The distance to NGC6949is given by de Vaucouleurs (1979)as5.1Mpc and is listed as5.5Mpc in Tully(1988), assuming a Hubble constant value of75km s?1Mpc?1. More recently,Eastman et al.(1996)derive a distance of5.7±0.7Mpc based on a Type II supernova,and Sharina et al.(1997)?nd a distance of6.4±0.4Mpc based on photometric observations of the brightest stars in the galaxy.Finally,Karachentsev et al.(2000)es-timate the distance to the NGC6946galaxy group (consisting of NGC6946and seven other small galax-ies)to be5.9±0.4Mpc,based on observations of the brightest blue giants in the galaxies.We choose to adopt a distance of5.9Mpc,as do Holt et al.(2003),Schlegel et al.(2003),and Larsen et al.(2002).The Galactic absorption column in the direction of NGC6946 is2.0×1021cm?2(Dickey&Lockman1990;Stark et al. 1992;Kalberla et al.2005).

NGC6946was?rst observed in X-rays with the Ein-stein satellite;three observations with the Einstein IPC were made in1979–1981.Analyzing these observations, Fabbiano&Trinchieri(1987)resolve the X-ray emission from the galaxy into two peaks.NGC6946was observed with the ROSAT PSPC in1992,twice with the ASCA satellite in1993and1994,and three times with the ROSAT HRI in1994–96.Schlegel(1994b)analyzes the ROSAT PSPC observation and resolves emission from the galaxy into nine point sources,as well as?nding ev-idence for di?use emission.Analyzing the?rst of the three ROSAT HRI observations and the second of the two ASCA observations Schlegel et al.(2000)detect14 point sources and di?use emission from the galaxy.Most recently,NGC6946has been observed?ve times with Chandra between2001and2004,and11times with XMM-Newton in2003–2006.The most detailed studies so far of the X-ray emission components of NGC6946 are presented in a pair of papers based on the?rst of the ?ve Chandra observations.Holt et al.(2003)study the point source population and?nd72sources;the di?use emission is extensively studied in Schlegel et al.(2003). The Chandra observations of NGC6946are summa-rized in Table1.These are all ACIS-S full-frame imag-ing observations taken in Timed Exposure mode.The frame time was in all cases set at the standard value of 3.2s,and events were telemetered in the Faint format. The observations span a period of about39months and have a cumulative good live exposure time of172.5ks. In each observation the majority of sources falls on the back-illuminated S3chip,and a smaller portion falls on the front-illuminated S2and/or S4chips.None of the observations covers the whole D25isophote.

6Fridriksson et al.

TABLE3

XMM-Newton EPIC Observations of NGC6946

MOS-1MOS-2PN

X-Ray Variability in NGC6946,NGC4485/907

TABLE4

Chandra Observations of NGC4485/4490

Start Date Instrument Obs.ID Exp.a(ks)Data Mode b 2000Nov3ACIS-S157919.52F 2004Jul27ACIS-S472538.41VF 2004Nov20ACIS-S472639.59VF

a Good live exposure time.

b Telemetry formats:F=Faint,VF= Very Faint.

detections),and23.6sources in the hard band,or45% of our53detections.Overall,we estimate that～28of our total85detections in the0.3?7keV band can be expected to arise from CBSs.

The ROSAT HRI and XMM-Newton EPIC observa-tions of NGC6946are summarized in Tables2and3.A total of11XMM-Newton EPIC observations have been made,all of which su?er from periods of high back-ground.Six of them are completely unusable and were therefore not analyzed further,and they are not included in Table3.

3.2.NGC4485/4490

NGC4485and NGC4490are a closely interacting pair of galaxies,variously classi?ed as spiral or irregular sys-tems(see Fig.1).In de Vaucouleurs et al.(1991)NGC 4490is classi?ed as type SB(s)d,and the smaller com-panion NGC4485as type IB(s)m.Both galaxies show signs of tidal disruption.Tully(1988)gives separate dis-tances of7.8Mpc(NGC4490)and9.3Mpc(NGC4485) to the two galaxies,assuming a Hubble constant value of75km s?1Mpc?1.These distances are adopted by Roberts&Warwick(2000)and Liu&Bregman(2005). Such disparate distances are,however,unphysical for such a closely interacting system.Roberts et al.(2002), Elmegreen et al.(1998a),and Read et al.(1997)there-fore assume a distance of7.8Mpc to both galaxies.

A consistent distance of8Mpc to the pair is adopted by Clemens&Alexander(2002),Clemens et.al(1998, 1999,2000),Thronson et al.(1989),and Viallefond et al. (1980),based on the suspected membership of the sys-tem in the CVn II cloud(de Vaucouleurs et al.1976), and this is the value we used.The Galactic absorp-tion column in the direction of NGC4485/4490is1.8×1020cm?2(Dickey&Lockman1990;Stark et al.1992; Kalberla et al.2005).

NGC4485/90has been studied at radio,infrared, and optical wavelengths and shows evidence for en-hanced star formation(Viallefond et al.1980;Klein 1983;Thronson et al.1989).Clemens et.al(1999) estimate a star formation rate in NGC4490of～4.7M⊙yr?1and a dynamical mass of～1.6×1010M⊙within8kpc(the companion NGC4485being less mas-sive by about a factor of8).The system was?rst ob-served in X-rays with the ROSAT PSPC in1991.Ana-lyzing those data,Read et al.(1997)detected four point-like sources,three in NGC4490and one in NGC4485. The galaxy pair was subsequently observed three times with the ROSAT HRI in1995and1996.Analyzing two of those observations,Roberts&Warwick(2000)only found one additional point source,an apparently tran-sient source coincident with NGC4490.Liu&Bregman

TABLE5

ROSAT HRI Observations of NGC

4485/4490

Start Date Seq.ID Exp.a(ks)

1996Jun18rh600855n0026.70

1996Nov26rh600855a0124.58

Note.—One additional ROSAT HRI ob-

servation was made.We did not make use of

it due to its shortness.

a Good live exposure time.

(2005)analyzed all three ROSAT observations as part of their study of ULXs using the ROSAT HRI archive. They found the same sources as Roberts&Warwick (2000).Most recently,the system was observed three times with Chandra between2000and2004and once with XMM-Newton in2002.Analyzing the?rst of the Chandra observations,Roberts et al.(2002)found31 point sources,29of those being coincident with NGC 4490,one coincident with NGC4485,and one source lo-cated in a bridge between the galaxies.

The Chandra observations of the NGC4485/90sys-tem are summarized in Table4.These are all ACIS-S full-frame imaging observations taken in Timed Expo-sure mode.The frame time was in all cases set at the standard value of3.2s,and events were telemetered in either the Faint or Very Faint formats.The observations span a period of about4yr and have a cumulative good live exposure time of97.5ks.In all three observations all the sources coincident with NGC4485/90fall within the S3chip.

The data were analyzed as described in§2.Source detection was performed on a8.8′×8.7′rectangle en-compassing the system.A total of38reliable source de-tections down to a luminosity of～1×1037ergs s?1were found to be coincident with the two galaxies.Of these, 33are coincident with NGC4490,three coincident with NGC4485,and two more are located in the bridge be-tween the galaxies(see Fig.1).The source catalog is presented in Table10.An adaptively smoothed color-coded image based on the co-added Chandra exposure is shown in Figure2.

Of the38sources,27had previously been detected by Roberts et al.(2002)and11had not been seen before. In addition,four of the sources reported in Roberts et al. (2002)fell below our threshold of detection signi?cance and are therefore not included in our https://www.doczj.com/doc/594645858.html,-paring our source locations to the USNO-A2.0Cata-logue(Monet et al.1998),we?nd no close matches be-tween the locations of foreground stars and our detected sources.There have been two historical supernovae in NGC4490:SN1982F,which is not detected,and re-cently SN2008ax.

We estimate how many of our detections can be ex-pected to arise from CBSs using the same procedure as the one described for NGC6946in§3.1.We use the re-sults of Clemens et.al(1998)to estimate that a typical absorption column through the NGC4485/90system is ～3.5×1021cm?2,giving a total absorption column of ～3.7×1021cm?2for CBSs behind NGC4485/90.Ap-plying the formulae of Bauer et al.(2004)then yields an estimate of～5for the expected number of CBSs among

8Fridriksson et

al.

Fig. 2.—Adaptively smoothed color-coded images based on the co-added Chandra exposures of NGC6946(left)and NGC4485/4490 (right).Red corresponds to X-rays with energies0.3?1keV,green to1?2keV,and blue to2?7keV.

our38detected sources.For comparison,we note that

Roberts et al.(2002),using the results of Giacconi et al.

(2001),attribute<4.5of their detections to CBSs.

The ROSAT HRI and XMM-Newton EPIC observa-

tions of NGC4485/90are summarized in Tables5and6.

The?rst of the ROSAT observations is too short to be

of signi?cant use to this study,and it is not included in

Table5.

4.PROPERTIES OF THE SOURCE POPULATIONS

4.1.Flux Variability

The variability properties of the sources in NGC6946

are summarized in Table11.Based on the source?ux

variability parameter S?ux de?ned in§2.4we classify

25of the85nonforeground sources,or29%,as variable

on timescales of weeks,months,or years.Of these,17

sources are seen to vary by more than a factor of2,and

we classify11sources(or13%of the85)as transient

candidates(two of those are recent supernovae).Ev-

idence for short-term(hours)variability,as de?ned in

§2.4,is seen in four,or5%,of the85sources.Two

Fig. 3.—Long-term light curve of the ULX in NGC6946

(CXOU J203500.7+601130).Diamonds represent Chandra ACIS

observations,crosses represent XMM-Newton EPIC observations,

and squares represent ROSAT HRI observations.

of those also show long-term variability.Unsurprisingly,

none of the sources associated with SNRs from the lists

of Matonick&Fesen(1997)and Lacey&Duric(2001)

shows variability of any kind above a level of2σ,with

the exception of the ULX(see§4.2.2).

The variability properties of the sources in NGC

4485/90are summarized in Table12.We classify15

of the38sources,or39%,as showing variability on

timescales of months or years.Of these,10sources vary

by more than a factor of2,and four sources(or11%of

the38)are transient candidates.Evidence for short-term

variability is seen in four of the38sources.All of those

also show long-term variability.

Due to the limited number of counts within each obser-

vation for most of the sources showing short-term vari-

ability,it is very di?cult(with one marginal exception)

to draw any concrete conclusions about the nature of the

variability(e.g.,to distinguish between burst-like behav-

ior and more continuous decline or rise in count rate).

The brightest of these sources,CXOU J203500.1+600908

in NGC6946,seems in the?rst Chandra observation to

show a burst-like increase in count rate on a timescale of

～5?10ks superposed on a steady decline in count rate

throughout the whole observation.

Where possible,the baseline of the long-term light

curves of the ULXs was extended by adding data points

from ROSAT HRI and XMM-Newton observations as de-

scribed in§2.5.Long-term light curves of the10bright-

est sources in NGC6946are shown in Figures3and4,

and of the10brightest sources in NGC4485/90in Fig-

ures5and 6.We emphasize that the error bars in

the light curves contain only the1σPoisson errors in

the counts.The ROSAT and XMM-Newton data are

generally of much lower quality than the Chandra data,

and comparisons of luminosities between di?erent instru-

ments should be regarded with some caution.Various

factors(e.g.,cross-calibration issues and uncertainties in

instrument responses and in assumed spectral shapes for

energy conversions)are likely to add to the errors.To

X-Ray Variability in NGC6946,NGC4485/909

TABLE6

XMM-Newton EPIC Observation of NGC4485/4490

MOS-1MOS-2PN

10

Fig.upper limits with

(1982)report absorption corrected luminosities of～7×1038ergs s?1and～4×1038ergs s?1in the0.2?4keV band(after scaling their values to our adopted distance). SN1980K was also observed by the ROSAT PSPC in 1992June.Schlegel(1994c)gives a luminosity estimate of～2×1037ergs s?1in the0.5?2keV range(scaled to our adopted distance).Type II SN1968D is seen in all?ve Chandra observations and has a luminosity of ～2×1037ergs s?1.The other four historical supernovae (SN1917A,SN1939C,SN1948B,and SN1969P)are not detected.

4.2.2.ULX in NGC6946

The only ultraluminous X-ray source in NGC6946,of-ten called MF16(Matonick&Fesen1997),has been ex-tensively studied.It was?rst detected with the Einstein IPC in1979–1981(Fabbiano&Trinchieri1987)and was later observed with the ROSAT PSPC in1992.Analyz-ing the ROSAT observation,Schlegel(1994a)derived an X-ray luminosity of3.7×1039ergs s?1in the0.5?2keV band(scaled to our adopted distance),and identi?ed the source as a supernova remnant based on an optical coun-terpart discovered by Blair&Fesen(1994).The rem-nant appears to be quite evolved,perhaps～103?104yr old(Blair&Fesen1994;Dunne et.al2000;Blair et al. 2001).Hubble Space Telescope images presented by Blair et al.(2001)reveal a three loop structure with an extent of1.4′′×0.8′′(corresponding to39×23pc at our adopted distance).Various models have been put forward to try to explain this unusually high luminosity from such an evolved SNR.Blair et al.(2001)propose that ejecta from a young supernova might be interacting with the dense shell of an older SNR;Dunne et.al(2000) suggest instead that a single supernova blast wave is in-teracting with a dense circumstellar nebula from a high-mass progenitor and that a hard spectral component in the ROSAT PSPC data comes from a pulsar wind nebula. Schlegel et al.(2003),analyzing the?rst Chandra obser-vation,argue from spectral considerations that neither of these scenarios can explain the data.Roberts&Colbert (2003)analyze the?rst two Chandra observations of the object and speculate that the luminosity of MF16arises from a black hole X-ray binary(BHXRB)within the SNR.They argue this based on(1)the point-like na-ture of the X-ray source,(2)the close resemblance of the source spectrum to spectra from other ULXs thought to be BHXRBs,(3)the short-timescale(minutes)variabil-ity of the hard component(1.1?10keV)of the?ux,and (4)the long-timescale drop of～13%in count rate be-tween the?rst and second Chandra observations(～3% thereof stemming from a degradation in e?ective area). Our K-S test does not detect short-timescale variations in the full0.3?7keV band for any of the Chandra observa-tions.We do,however,see de?nite long-term variability in the Chandra data(see light curve in Fig.3).There is a drop in luminosity of～5%between the?rst and

11

Fig.5.—Long-term light Chandra ACIS observations, crosses represent

second observations,and then a much larger drop be-tween the second and third observations;the luminosity in the third observation is～79%of the original?rst ob-servation value.Two weeks later,in the fourth Chandra observation,the luminosity has again increased to～93% of its original value.We also see clear evidence of vari-ability in the XMM-Newton data,most notably a～20% jump in luminosity in the12days between two obser-vations in2004June.Finally,we see variations in the soft color with a signi?cance of2.9σ(see Fig.7).These spectral variations do not seem to have a clear correlation with?ux.There is spectral softening associated with the drop in?ux between the second and third Chandra ob-servations,but there is no detectable hardening when the ?ux subsequently increases again.Overall,this observed variability considerably strengthens the case for an ac-creting object as the source of at least part of the X-ray emission from MF16.

4.2.3.ULXs in NGC4485/4490

The NGC4485/90system contains a high number of ULXs,a total of eight.In a comprehensive sur-vey of nearby galaxies observed with the ROSAT HRI, Liu et al.(2006,see also Liu&Bregman2005)?nd an average rate of～0.5ULXs per galaxy.The rate is higher when only considering late-type galaxies and still higher for starburst galaxies(～1.0).Considerably higher num-bers,however,are not unusual for interacting galaxies (see,e.g.,Brassington et al.2007),an extreme case being the Antennae,with14known ULXs(Zezas et al.2006). Seven of the ULXs in the NGC4485/90system are in NGC4490and one is in NGC4485.We numerate them here in order of right ascension(see Table10).Two of them,ULX-5and ULX-7,have not been identi?ed as being ultraluminous before,their luminosities having entered the ULX range only in the most recent Chandra observation.

The maximum luminosities of the ULXs range from 1.0×1039ergs s?1to4.1×1039ergs s?1.These sources show a lot of variability.Long-term?ux variability above the3σlevel is exhibited by all but one of them(see light curves in Figs.5and6).ULX-7is a transient,ULX-5 varies by a factor of～11and ULX-6by a factor of ～5.The others vary by less than a factor of2.ULX-5 shows short-term?ux variability.Two sources,ULX-6and ULX-8,have signi?cant variations in their hard color.In both cases,there is a clear transition from a harder higher luminosity state to a softer lower luminos-ity one and back(see Fig.7).

Vazquez et al.(2007)use the Infrared Spectrograph on the Spitzer Space Telescope to do mid-infrared spec-tral diagnostics on six of the ULXs(all except ULX-5and ULX-7).They?nd that?ve of those show ionization features that they claim indicate accretion, whereas the sixth source,ULX-1,seems to be more con-sistent with a SNR.As pointed out by Roberts et al. (2002),ULX-1is coincident with a radio source,FIRST J123029.4+413927,which also points towards a SNR ori-gin for ULX-1.However,we see a～30%drop in lumi-nosity in the four months between the second and third Chandra observations—behavior that is more typical of an accreting XRB than a SNR.This is reminiscent of the ULX in NGC6946,which has also been associated with a SNR but whose X-ray variability indicates an accreting XRB.

The abundance of variability among the ULXs in NGC 4485/90is similar to what is seen in the Antennae. Zezas et al.(2006)?nd that two of the ULXs in the Antennae show variability on a timescale of a few days. Twelve out of14ULXs show long-term variability,one being a transient,and four of the ULXs occasionally have luminosities below the ULX limit.In NGC4485/90we

12

Fig. 6.—represent upper limits with3σGaussian con?dence.

?nd that four of the eight ULXs have a luminosity be-low1039ergs s?1in at least one of the three Chandra observations.It is therefore clear that a single observa-tion of a galaxy is by no means guaranteed to discover the galaxy’s full ULX population.Surveys such as that of Liu et al.(2006),where many of the galaxies are only observed once or twice,can only give a lower limit to the average number of sources in a galaxy with the potential of being ultraluminous at one time or other.

4.3.Hardness Ratios

4.3.1.Variability

The hardness ratios of the sources in NGC6946,both for each observation and for the co-added exposure,are given in Tables13and14.The hardness ratios for the NGC4485/90sources are similarly given in Table15. Signi?cance parameters for variability in the hardness ratios between observations are given in Tables11(NGC 6946)and12(NGC4485/90).Variability above3σin ei-ther of the ratios is only detected in two of the sources in NGC6946and three of the sources in NGC4485/90.In addition,the ULX in NGC6946shows a2.9σvariation in its hard color.We note that a much larger fraction of the sources probably undergoes some spectral varia-tion,but most of the sources have too few counts for the hardness ratios to be very sensitive to spectral changes. Color-luminosity plots for the sources exhibiting signif-icant hardness ratio variability are shown in Figure7. Four of these sources(one of those being SN2002hh) seem to show a clear correlation between higher luminos-ity and increased hardness,whereas the other two show more complicated behavior.Previous studies of exter-nal galaxies have routinely found sources with spectral variability,in some cases with spectral behavior reminis-cent of Galactic XRBs;?ux-color transitions have also been observed in ULXs(Fabbiano2006and references therein).Zezas et al.(2006)?nd signs of variability in hardness ratios of21of their～70detected sources in the Antennae;some of these are ULXs.As in our case, they?nd that the variability does not follow the same pattern for all sources.They see sources that become harder with higher luminosity,as we do,but also sources that soften with increased luminosity.In addition,some of the sources show no regular pattern,or no signi?cant variation in luminosity.

4.3.2.Supersoft Sources

Two sources have especially soft spectra and are strong candidates for supersoft sources(SSSs;see,e.g., Di Stefano&Kong2003).CXOU J203426.2+600914in NGC6946has all of its68source counts below1keV, and CXOU J123034.5+413834in NGC4490has32of its total35source counts below1keV,25counts be-ing below0.65keV.Both sources have a luminosity of ～9×1036ergs s?1,and neither one shows evidence for variability.

4.3.3.Spectral Classi?cation

Color-color diagrams for the sources in NGC6946and NGC4485/90,based on the co-added exposures,are shown in Figure8.The fact that most of the sources do not show signi?cant variation in their hardness ra-tios between observations provides justi?cation for using hardness ratios calculated from the co-added exposure to describe the source populations’spectral properties.The classi?cation scheme of Prestwich et al.(2003)discussed in§2.3,is overlaid.As mentioned before,although a source’s position in a color-color diagram does not give conclusive information about the nature of the source, the overall distribution of sources should give us some information about the population as a whole.Also indi-cated in the color-color diagrams is the physically allowed region,covering all combinations of HR1and HR2possi-ble if the net counts in all the energy bands(S,M,H,T;

X-Ray Variability in NGC6946,NGC4485/90

13

Fig.7.—Soft or hard color as a function of luminosity for sources that show signi?cant variation in their hardness ratios.Numbers next to data points indicate their order in time.

see§2.3)are non-negative.Due to background subtrac-

tion in cases of very few source counts,some of the hard-

ness ratios fall outside this region.They are,however,

all consistent with the physically allowed region within

their1σerrors.

Prestwich et al.(2003)note that,while thermal SNRs

are in general expected to have?0.9

indicated in the classi?cation scheme,SNRs whose spec-

tra are dominated by nonthermal components will have

somewhat harder spectra and are likely to be located in

the LMXB or even absorbed sources part of the color-

color diagram.We see in Figure8that the locations of

the sources associated with SNRs in NGC6946are in

good agreement with this.

For NGC4485/90,all but two of the38sources fall in

the XRB regions of the color-color diagram,with roughly

equal portions falling in the LMXB and HMXB regions.

In NGC6946there seems to be a much larger SNR com-

ponent to the population.In addition to the four de-

tected historical supernovae and the six sources associ-

ated with optically or radio identi?ed SNRs,～5sources

have colors consistent with thermal SNRs.The rest of

the sources in NGC6946(apart from the SSS candidate)

have colors consistent with XRBs,again with roughly

equal portions in the LMXB and HMXB regions.We

note that a large portion of the sources has colors con-

sistent with both regions.The large presence of HMXBs

in these systems,indicated by the color-color diagrams,

is not surprising given the high level of star formation

observed.

All the ULXs have colors consistent with XRBs.The

ULX in NGC6946falls?rmly in the LMXB region,

whereas six of the ULXs in NGC4485/90have col-

ors more consistent with HMXBs.Variable and tran-

sient sources are equally divided between the LMXB

and HMXB regions in NGC4485/90.For NGC6946,

these sources seem to slightly favor the LMXB region,

but this is hardly a signi?cant di?erence.The most vari-

able sources(those that vary by a factor of10or more)

are also seen to be roughly equally divided between the

LMXB and HMXB regions in both galaxies.

4.4.Luminosity Functions

We construct X-ray luminosity functions(XLFs)for

each observation,as well as the co-added exposure,of

both NGC6946and NGC4485/90.We use luminosities

from the full0.3?7keV band.In the case of NGC6946,

where parts of the galaxy fell outside the Chandra detec-

tors in each observation,only sources that fell within the

detectors in all?ve observations were considered.Hence,

24of the85nonforeground sources were discarded.This

was done to make sure that when comparing the XLFs

from di?erent observations we are comparing the same

source population.

To avoid any e?ects of incompleteness at the low-

luminosity end of the XLF,we set a conservative com-

pleteness limit for both galaxies and consider only the

portion of the XLF above that limit.To facilitate com-

parisons between di?erent observations we use the same

completeness limit for all observations of each galaxy.We

?t a simple power law to the unbinned distribution for

each observation using the Cash statistic(Cash1979).

14Fridriksson et al.

Fig.8.—Color-color diagrams for the sources in NGC6946and NGC4485/4490based on the co-added Chandra exposures.The classi?cation scheme of Prestwich et al.(2003)is overlaid.Histor-ical supernovae are represented with boxes,SNRs with diamonds, ULXs with crosses,and other sources with circles.Blue indicates that long-term variability is detected,green that it is not,and red denotes transient candidates.The triangle enclosed by the dashed lines represents the physically allowed region where net counts in all energy bands are non-negative.Due to background subtraction, faint sources can fall outside this region.

In order to test the null hypothesis that the XLFs of dif-ferent observations of the same galaxy are derived from the same parent distribution,we compare the XLFs in pairs using a two-sided Kolmogorov-Smirnov test.

The XLFs for NGC6946are shown in Figure9.We adopt a completeness limit of2×1037ergs s?1.Judging from the?gure,the XLF of the galaxy does not seem to

TABLE7

Indices of

XLFs of NGC

6946

Obs.αa

10430.61±0.13

44040.63±0.10

46310.67±0.11

46320.72±0.13

46330.67±0.12

0.73±0.14

Best-?t cumulative

Uncertainties

are estimated90%

intervals.

observations.This is borne out by

K-S tests between the?ve

which yield signi?cance levels

0.99and thus do not warrant re-

of a common parent distri-

performing the K-S test between

and each of the observations,we

levels,ranging from0.13to0.77.

slopes of the XLFs are shown in

all cases～0.6?0.7and are in good

other.We note that Holt et al.

of0.68±0.03for the?rst Chandra

with our value of0.61±0.13.

4485/90are shown in Figure9.

limit of4×1037ergs s?1.

seem to be signi?cant variation

observations.This is supported by

the three observations,which

from0.58to0.97.Performing

the co-added exposure and indi-

yields higher signi?cance levels here

in contrast to NGC6946.The

slopes of the XLFs shown in Table8

other and are all～0.4?0.5.We note

(2002)derive a slope of0.57±0.10

observation,in agreement with our

There is an indication in Figure9

break or cuto?in the XLFs,which

for the～3most luminous sources.

?tting a broken power law to

led to a best-?t break lumi-nosity of～(2?3)×1039ergs s?1and a slope for the low-luminosity portion that is～0.05lower than for the simple unbroken power law(i.e.,～0.4).The slope of the high-luminosity portion was,however,in all cases very poorly constrained.

We use the results of Bauer et al.(2004)to assess whether CBSs are likely to have a signi?cant e?ect on the XLFs.In NGC6946we expect～8CBSs among the～25sources typically above the completeness limit and within the region covered by all?ve Chandra obser-vations.In NGC4485/90we estimate that～3of the ～23sources typically above the completeness limit can be expected to be CBSs.Based on these numbers alone, one might expect that CBSs could have a signi?cant ef-fect in the case of NGC6946but probably only a small e?ect for NGC4485/90.As it turns out,the cumula-

X-Ray Variability in NGC 6946,NGC 4485/90

15

Fig.9.—Cumulative X-ray luminosity functions for all the Chandra observations and the co-added exposures of NGC 6946and NGC 4485/4490.The vertical lines show the adopted com-pleteness limits.

tive number-?ux slopes for CBSs derived in Bauer et al.(2004)are quite similar to the ones for the XLFs:0.55for the 0.5?2keV band and 0.56for the 2?8keV band.Contamination of our sample by CBSs is there-fore likely to have only a small e?ect in both cases.The true slopes for NGC 4485/90are probably slightly ?atter than those derived above and slightly steeper for NGC 6946.However,the change in XLF slopes due to CBSs is almost certainly well within the uncertainties quoted in Tables 7and 8.

Our results agree well with previous results for other galaxies.As mentioned in §1,XLFs have been seen to be remarkably stable in spite of variability among in-dividual sources,and NGC 6946and NGC 4485/90do

TABLE 8

Power-law Indices of the XLFs of NGC

4485/90Obs.αa 15790.45±0.1047250.49±0.0947260.42±0.08Co-added

0.45±0.08

a

Best-?t cumulative slope.Uncertainties given are estimated 90%con?dence intervals.

not seem to be an exception.Single-observation snap-shots of their XLFs therefore seem to represent rather well their shape averaged over longer times.Their cumu-lative XLF slopes fall ?rmly in the regime of starburst galaxies,whose slopes are typically between 0.4and 0.8(Fabbiano 2006)—another clear indication of the young stellar populations in these two systems.

5.SUMMARY AND CONCLUSIONS

We have presented a study of the X-ray source pop-ulations in the spiral galaxy NGC 6946and the ir-regular/spiral interacting galaxy pair NGC 4485/4490.We analyzed data from ?ve Chandra observations of NGC 6946and from three Chandra observations of NGC 4485/90.We detect 90point sources coincident with NGC 6946(excluding a small circumnuclear region)down to luminosities of a few times 1036ergs s ?1.We as-sociate ?ve of these with foreground stars.Seven sources are coincident with optically or radio identi?ed SNRs,and four are supernovae from the past 40years.We de-tect 38sources coincident with NGC 4485/90down to a luminosity of ～1×1037ergs s ?1.

In NGC 6946,25of the 85sources exhibit long-term (weeks to years)variability in luminosity;11are transient candidates.We detect short-term (hours)variability in four sources.Three sources show signi?cant variability in their hardness ratios.We ?nd that the single ULX in NGC 6946,the SNR known as MF16,exhibits long-term variability in ?ux and color that strongly supports speculations of its high luminosity arising from an XRB within the remnant.

In NGC 4485/90,15of the 38sources show ?ux vari-ability on timescales of months to years;four are tran-sient candidates.Short-term variability is seen for four sources,and three show variability in their hardness ra-tios.NGC 4485/90contains eight ULXs.Two of these have not been identi?ed as ULXs before;this shows the value of long-term monitoring in identifying ultralumi-nous sources.All but one of the ULXs exhibit long-term variability,and one of them is a transient.One of the ULXs,which has been associated with a SNR based on spectral characteristics and its spatial coincidence with a radio source,shows clear long-term variability pointing to an accreting XRB.We detect short-term variability for one ULX,and two have signi?cant variations in color.This abundant variability among the ULXs clearly points to accretion as the source of luminosity.

Consistent with the widespread variability seen within the source populations,the X-ray colors of the sources

16Fridriksson et al.

indicate that the populations are dominated by XRBs. The source population of NGC6946also seems to contain a sizable SNR component,perhaps～15%?20%of the detected sources.The distribution of colors among the sources in both NGC6946and NGC4485/90indicates roughly equal fractions of LMXBs and HMXBs.Such a signi?cant presence of HMXBs is consistent with the fact that both systems show high star formation activity. The shape of the XLFs of NGC6946and NGC4485/90 does not change signi?cantly between observations,and seems to be well represented by single-observation snap-shots.The XLF of NGC6946(above2×1037ergs s?1) can be described by a power law with cumulative slope ～0.6?0.7.The XLF of NGC4485/90can be described by a power law with cumulative slope～0.4between 4×1037and2×1039ergs s?1.Above～2×1039ergs s?1, the luminosity function drops o?rather sharply.The ?atness of the slopes(especially for NGC4485/90)is an-other testament to the systems’high star formation rate and young stellar population.

This work was supported by Chandra Award https://www.doczj.com/doc/594645858.html,e was made of data obtained from the High Energy Astrophysics Science Archive Research Cen-ter(HEASARC),provided by NASA’s Goddard Space Flight Center.We thank the referee for thorough read-ing of the paper and constructive comments.

REFERENCES

Bauer,F.E.,Alexander,D.M.,Brandt,W.N.,Schneider,D.P., Treister,E.,Hornschemeier,A.E.,&Garmire,G.P.2004,AJ, 128,2048

Blair,W.,&Fesen,R.1994,ApJ,424,L103

Blair,W.P.,Fesen,R.A.,&Schlegel,E.M.2001,AJ,121,1497 Brassington,N.J.,Ponman,T.J.,&Read,A.M.2007,MNRAS, 377,1439

Broos,P.S.,Townsley,L.K.,Getman,K.,&Bauer, F. E. 2002,ACIS Extract,An ACIS Point Source Extraction Package(University Park:Pennsylvania State Univ.), https://www.doczj.com/doc/594645858.html,/xray/docs/TARA/ae guide.html Canizares,C.R.,Kriss,G.A.,&Feigelson,E.D.1982,ApJ,253,

L17

Cash,W.1979,ApJ,228,939

Clemens,M.S.,Alexander,P.,&Green,D.A.1998,MNRAS,297, 1015

———.1999,MNRAS,307,481

———.2000,MNRAS,312,236

Clemens,M.S.,&Alexander,P.2002,MNRAS,333,39 Crosthwaite,L.P.,&Turner,J.L.2007,ApJ,134,1827

David,L.P.,et al.1999,The ROSAT High Resolution Imager (HRI)Calibration Report(Cambridge:SAO)

Davis,S.D.,&Mushotzky,R.F.2004,ApJ,604,653

de Vaucouleurs,G.1979,ApJ,227,729

de Vaucouleurs,G.,de Vaucouleurs,A.,&Corwin,H.G.,Jr.1976, Second Reference Catalogue of Bright Galaxies(Austin:Univ. Texas Press)

de Vaucouleurs,G.,de Vaucouleurs,A.,Corwin,H.G.,Jr.,Buta, R.J.,Paturel,G.,&Fouque,P.1991,Third Reference Catalogue

of Bright Galaxies(New York:Springer)

Dickey,J.M.,&Lockman,F.J.1990,ARA&A,28,215

Diehl,R.,et al.2006,Nature,439,45

Di Stefano,R.,&Kong,A.K.H.2003,ApJ,592,884

Dunne,B.C.,Gruendl,R.A.,&Chu,Y.-H.2000,AJ,119,1172 Eastman,R.G.,Schmidt,B.P.,&Kirshner,R.1996,ApJ,466, 911

Elmegreen,D.E.,Chromey,F.R.,Knowles,B.D.,&Wittenmyer, R.A.1998a,AJ,115,1433

Elmegreen,D.E.,Chromey,F.R.,&Santos,M.1998b,AJ,116, 1221

Fabbiano,G.,&Trinchieri,G.1987,ApJ,315,46

Fabbiano,G.,&White,N.E.2006,in Compact Stellar X-Ray Sources,ed.W.H.G.Lewin&M.van der Klis(Cambridge: Cambridge Univ.Press),475

Fabbiano,G.2006,ARA&A,44,323

Gehrels,N.1986,ApJ,303,336

Getman,K.V.,et al.2005,ApJS,160,319

Giacconi,R.,et al.2001,ApJ,551,624

Grimm,H.-J.,McDowell,J.,Zezas,A.,Kim,D.-W.,&Fabbiano, G.2005,ApJS,161,271

———.2007,ApJS,173,170

Holt,S.S.,Schlegel,E.M.,Hwang,U.,&Petre,R.2003,ApJ, 588,792

Kalberla,P.M.W.,Burton,W.B.,Hartmann,D.,Arnal,E.M., Bajaja,E.,Morras,R.&Poeppel,W.G.L.2005,A&A,440, 775

Karachentsev,I.D.,Sharina,M.E.,&Huchtmeier,W.K.2000,

A&A,362,544

Kilgard,R.E.,et al.2005,ApJS,159,214

Klein,U.1983,A&A,121,150

Kong,A.K.H.,Garcia,M.R.,Primini,F.A.,Murray,S.S.,Di Stefano,R.,&McClintock,J.E.2002,ApJ,577,738

Kraft,R.P.,Kregenow,J.M.,Forman,W.R.,Jones,C.,&Murray, S.S.2001,ApJ,560,675Kuulkers,E.2004,Nucl.Phys.B Proc.Suppl.,132,466

Lacey,C.K.,&Duric,N.2001,ApJ,560,719

Larsen,S.S.,Efremov,Y.N.,Elmegreen,B.G.,Alfaro,E.J.,

Battinelli,P.,Hodge,P.W.,&Richtler,T.2002,ApJ,567,896

Li,W.2002,IAU Circ.8005,

https://www.doczj.com/doc/594645858.html,/iauc/08000/08005.html

Liu,J.-F.,&Bregman,J.N.2005,ApJS,157,59

Liu,J.-F.,Bregman,J.N.,&Irwin,J.2006,ApJ,642,171

Matonick,D.M.,&Fesen,R.A.1997,ApJS,112,49

Miller,M.C.,&Colbert,E.J.M.2004,Int.J.Mod.Phys.D,13,

1

Misra,K.,Pooley,D.,Chandra,P.,Bhattacharya,D.,Ray,A.K.,

Sagar,R.,&Lewin,W.H.G.2007,MNRAS,381,280

Monet,D.,et al.1998,USNO-A V2.0,A Catalog of Astrometric

Standards(Flagsta?:USNO)

Nikiforov,I.I.,Petrovskaya,I.V.,&Ninkovic,S.2000,in IAU

Colloq.174,Small Galaxy Groups,ed.M.J.Valtonen&C.Flynn

(San Francisco:ASP),399

Prestwich,A.H.,Irwin,J.A.,Kilgard,R.E.,Krauss,M.I.,Zezas,

A.,Primini,F.,Kaaret,P.,&Boroson,

B.2003,ApJ,595,719

Read,A.M.,Ponman,T.J.,&Strickland,D.K.1997,MNRAS,

286,626

Rho,J.,Jarrett,T.H.,Chugai,N.N.,&Chevalier,R.A.2007,

ApJ,666,1108

Roberts,T.P.,&Colbert,E.J.M.2003,MNRAS,341,L49

Roberts,T.P.,&Warwick,R.S.2000,MNRAS,315,98

Roberts,T.P.,Warwick,R.S.,Ward,M.J.,&Murray,S.S.2002,

MNRAS,337,677

Sauty,S.,Gerin,M.,&Casoli,F.1998,A&A,339,19

Schlegel,E.M.1994a,ApJ,424,L99

———.1994b,ApJ,434,523

———.1994c,AJ,108,1893

Schlegel,E.M.,Blair,W.P.,&Fesen,R.A.2000,AJ,120,791

Schlegel,E.M.,Holt,S.S.,&Petre,R.2003,ApJ,598,982

Sharina,M.E.,Karachentsev,I.D.,&Tikhonov,N.A.1997,AstL,

23,373

Sivako?,G.R.,Jordan,A.,Juett,A.M.,Sarazin,C.L.,&Irwin,J.

M.2005a,in IAU Symp.230,Populations of High Energy Sources

in Galaxies,ed.E.J.A.Meurs&G.Fabbiano(Cambridge:

Cambridge Univ.Press),210

Sivako?,G.R.,Sarazin,C.L.,&Jordan,A.2005b,ApJ,624,L17

Stark,A.A.,Gammie,C.F.,Wilson,R.W.,Bally,J.,Linke,R.

A.,Heiles,C.,&Hurwitz,M.1992,ApJS,79,77

Tacconi,L.J.,&Young,J.S.1986,ApJ,308,600

Thronson,H.A.,Jr.,Hunter,D.A.,Casey,S.,Latter,W.B.,&

Harper,D.A.1989,ApJ,339,803

Townsley,L.K.,Feigelson,E.D.,Montmerle,T.,Broos,P.S.,Chu,

Y.-H.,&Garmire,G.P.2003,ApJ,593,874

Tully,R. B.1988,Catalog of Nearby Galaxies(Cambridge:

Cambridge Univ.Press)

Vazquez,G.A.,Hornschemeier,A.E.,Colbert,E.,Roberts,T.P.,

Ward,M.J.,&Malhotra,S.2007,ApJ,658,L21

Viallefond,F.,Allen,R.J.,&de Boer,J.A.1980,A&A,82,207

Zezas,A.,Fabbiano,G.,Baldi,A.,Schweizer,F.,King,A.R.,

Ponman,T.J.,&Rots,A.H.2006,ApJS,166,211

Zezas,A.,Fabbiano,G.,Baldi,A.,Schweizer,F.,King,A.R.,Rots,

A.H.,&Ponman,T.J.2007,ApJ,661,135

Zimmermann,U.,Boese,G.,Becker,W.,Belloni,T.,Doebereiner,

S.,Izzo, C.,Kahabka,P.,&Schwentker,O.1998,EXSAS

User’s Guide(Garching:ROSAT Scienti?c Data Center),

http://www.mpe.mpg.de/xray/wave/rosat/doc/users-guide/exsasguide.php

20Fridriksson et al.

TABLE11

Chandra V ariability Properties for NGC6946Sources

K-S Test for Short-Term Flux Variability a Long-Term Variability No.Source Designation Obs.ID Obs.ID Obs.ID Obs.ID Obs.ID Flux Hardness Ratios Comments f CXOU J10434404463146324633S flux b R c S HR1d S HR2e 1203419.0+6010070.120.94······0.83 2.2 2.40.50.8

2203421.4+6010170.960.98······0.39 2.0 3.90.60.2

3203423.4+601039···0.66······0.13 4.01100.70.5l

4203424.7+6010380.650.68······0.29 2.5 3.00.9 1.4

5203425.0+6009060.30·········0.1511.973.00.80.5l

6203426.1+6009090.480.69······0.7710.9 2.70.6 1.6l

7203426.2+6009140.580.47······0.49 1.2 1.50.40.3

8203429.1+6010510.330.85········· 3.2>1.50.50.9l

9203431.5+6006380.25············ 1.97.10.40.3

10203431.5+601056············0.46 5.578.30.30.7l

11203432.0+6012070.150.39···0.33··· 1.6>1.4 1.6 1.7

12203432.4+6008210.79············ 6.0>5.00.00.0l

13203434.4+6010320.030.65···0.820.13 3.3 1.8 1.50.9l,star 14203435.3+6007420.220.44······0.17 1.7 4.00.30.3

15203436.1+6008390.670.74···0.230.55 1.6 3.5 1.10.7

16203436.4+6005580.300.41········· 1.7 1.70.40.4

17203436.5+6009300.210.69···0.930.858.2 1.6 3.5 1.7l,sp 18203437.2+6009540.020.92···0.160.90 1.8 6.8 1.1 1.0

19203437.2+6010190.970.45···0.750.570.7 2.3 1.1 1.0

20203437.9+6004340.420.460.18······0.7 1.20.9 1.3

21203439.8+6008220.860.950.810.430.11 2.6 3.0 1.3 1.1

22203440.5+6009460.18···0.820.870.91 1.47.9 1.0 1.1

23203441.3+6008460.220.440.150.440.58 1.3 2.60.80.5

24203442.0+6005290.070.350.37···0.29 1.5 4.8 1.2 1.4

25203443.1+6006520.34···0.910.13··· 1.77.20.30.6

26203444.2+600719···0.290.920.600.4410.22250.6 3.5l,sp 27203445.9+6010490.010.390.880.160.97 2.1 5.00.50.8

28203446.3+6013280.360.020.130.150.80 1.4 1.7 1.4 1.5

29203447.1+6008500.65············ 4.0>2.30.00.0l

30203447.5+6010030.610.970.200.730.29 1.5 2.0 2.3 1.1

31203447.6+6009320.950.580.310.900.428.413.6 1.6 1.2l

32203448.4+6008110.010.720.300.100.30 5.7 3.0 1.4 1.7l

33203448.6+6009410.810.990.75···0.44 3.8>2.30.40.7l

34203448.8+6005540.182.4×10?30.750.010.07 3.5 1.5 1.2 1.5s,l,star 35203449.0+6012170.850.330.470.500.50 2.8 1.5 1.9 1.8

36203449.4+6013420.800.230.572.2×10?30.32 1.7 2.6 1.40.9s

37203449.7+6010110.460.540.660.370.120.9 1.5 1.0 1.2

38203449.7+6008060.260.30···0.830.28 1.5 5.20.70.6

39203449.7+6010200.950.920.640.090.07 1.5 2.80.9 1.6

40203450.0+6009240.430.340.340.870.33 1.0 1.6 1.3 1.1

41203450.4+6010160.950.960.102.4×10?3··· 1.88.50.4 1.0s

42203450.4+600724···0.820.340.400.99 6.9>22.7 1.1 1.6l

43203450.7+6007470.690.040.220.230.150.6 1.80.40.6

44203450.7+6012070.700.214.6×10?30.840.90 1.58.50.7 1.1

45203450.9+6010200.650.050.120.830.61 1.4 1.5 1.1 1.5

46203451.5+6012480.130.360.980.720.31 1.5 2.9 1.0 1.1

47203451.5+6009090.130.810.120.890.77 1.312.30.6 1.1

48203453.3+6010550.500.150.190.630.15 1.2 2.3 1.3 1.1

49203453.4+6007190.550.26···0.200.59 6.125.80.8 1.5l

50203453.7+6009100.070.590.780.930.300.9 1.7 1.50.5

51203455.6+6009300.300.280.410.340.11 3.28.2 1.40.8l

52203456.5+6008340.01 1.000.820.500.06 4.2 1.7 1.60.8l

53203456.5+6008190.010.570.830.700.38 1.2 2.0 1.5 1.0

54203456.8+6005320.770.870.810.010.62 2.0 2.4 1.60.7

55203456.9+6012090.370.250.600.230.16 1.2 3.1 1.10.7star 56203456.9+6008260.080.080.690.460.02 3.612.80.4 1.0l

57203457.2+6007330.700.06········· 2.1>1.9 1.0 1.0star 58203457.7+6009480.350.100.400.880.08 5.4 1.8 1.2 1.0l

59203458.4+6009340.190.640.010.530.83 1.2 1.60.5 1.5

60203500.1+6009086.2×10?150.240.500.760.8012.2 1.8 1.20.9s,l 61203500.4+6008590.180.770.340.370.48 2.2 4.60.8 1.1

62203500.6+6012500.080.580.800.770.95 3.7 4.3 1.30.8l

63203500.7+6011300.480.670.250.310.618.9 1.2 2.9 1.8l

64203500.9+6010100.860.400.110.540.64 2.9 1.30.7 2.1

65203501.1+6009230.960.34······0.76 1.2 4.70.80.5

66203501.9+6010030.980.040.260.130.96 2.3 1.50.7 1.9

67203504.6+6011170.480.590.810.840.36 1.8 1.9 1.40.6

68203504.6+6009180.260.690.260.630.43 1.1 2.3 1.00.9

69203505.3+6006230.120.220.570.510.910.8 1.2 1.5 1.6

70203505.5+6007420.73···0.200.360.58 1.2 2.6 1.20.6

71203506.5+6010400.280.410.020.850.20 2.5 2.4 1.3 1.7

72203508.1+6011130.680.760.960.350.89 1.7 2.1 1.6 1.0

高二《甜美纯净的女声独唱》教案

高二《甜美纯净的女声独唱》教案 一、基本说明 教学内容 1）教学内容所属模块：歌唱 2）年级：高二 3）所用教材出版单位：湖南文艺出版社 4）所属的章节：第三单元第一节 5）学时数： 45 分钟 二、教学设计 1、教学目标： ①、在欣赏互动中感受女声的音域及演唱风格，体验女声的音色特点。 ②、在欣赏互动中，掌握美声、民族、通俗三种唱法的特点，体验其魅力。 ③、让学生能够尝试用不同演唱风格表现同一首歌。 ④、通过学唱歌曲培养学生热爱祖国、热爱生活的激情。 2、教学重点： ①、掌握女高音、女中音的音域和演唱特点。 ②、掌握美声、民族、通俗三种方法演唱风格。 3、教学难点： ①、学生归纳不同唱法的特点与风格。

②、学生尝试用不同演唱风格表现同一首歌。 3、设计思路 《普通高中音乐课程标准》指出：“音乐课的教学过程就是音乐的艺术实践过程。”《甜美纯净的女声独唱》作为《魅力四射的独唱舞台》单元的第一课，是让学生在丰富多彩的歌唱艺术形式中感受出女声独唱以其优美纯净的声音特点而散发出独特的魅力。为此，本课从身边熟悉的人物和情景入手，激发学生学习兴趣，把教学重心放在艺术实践中，让学生在欣赏、学习不同的歌唱风格中，培养自己的综合欣赏能力及歌唱水平。在教学过程中让学生体会不同风格的甜美纯净女声的内涵，感知优美纯净的声音特点而散发出的独特魅力，学会多听、多唱，掌握一定的歌唱技巧，提高自己的演唱水平。为实现以上目标，本人将新课标“过程与方法”中的“体验、比较、探究、合作”四个具体目标贯穿全课，注重学生的个人感受和独特见解，鼓励学生的自我意识与创新精神，强调探究、强调实践，将教学过程变为整合、转化间接经验为学生直接经验的过程，让学生亲身去感悟、去演唱，并力求改变现在高中学生普遍只关注流行歌曲的现状，让学生自己确定最适合自己演唱的方法，自我发现、自我欣赏，充分展示自己的的声音魅力。 三、教学过程 教学环节及时间教师活动学生活动设计意图

尊重的素材

尊重的素材（为人处世） 思路 人与人之间只有互相尊重才能友好相处 要让别人尊重自己，首先自己得尊重自己 尊重能减少人与人之间的摩擦 尊重需要理解和宽容 尊重也应坚持原则 尊重能促进社会成员之间的沟通 尊重别人的劳动成果 尊重能巩固友谊 尊重会使合作更愉快 和谐的社会需要彼此间的尊重 名言 施与人，但不要使对方有受施的感觉。帮助人，但给予对方最高的尊重。这是助人的艺术，也是仁爱的情操。—刘墉 卑己而尊人是不好的，尊己而卑人也是不好的。———徐特立 知道他自己尊严的人，他就完全不能尊重别人的尊严。———席勒 真正伟大的人是不压制人也不受人压制的。———纪伯伦 草木是靠着上天的雨露滋长的，但是它们也敢仰望穹苍。———莎士比亚 尊重别人，才能让人尊敬。———笛卡尔 谁自尊，谁就会得到尊重。———巴尔扎克 人应尊敬他自己，并应自视能配得上最高尚的东西。———黑格尔 对人不尊敬，首先就是对自己的不尊敬。———惠特曼

每当人们不尊重我们时，我们总被深深激怒。然而在内心深处，没有一个人十分尊重自己。———马克·吐温 忍辱偷生的人，绝不会受人尊重。———高乃依 敬人者，人恒敬之。———《孟子》 人必自敬，然后人敬之；人必自侮，然后人侮之。———扬雄 不知自爱反是自害。———郑善夫 仁者必敬人。———《荀子》 君子贵人而贱己，先人而后己。———《礼记》 尊严是人类灵魂中不可糟蹋的东西。———古斯曼 对一个人的尊重要达到他所希望的程度，那是困难的。———沃夫格纳 经典素材 1元和200元 （尊重劳动成果） 香港大富豪李嘉诚在下车时不慎将一元钱掉入车下，随即屈身去拾，旁边一服务生看到了，上前帮他拾起了一元钱。李嘉诚收起一元钱后，给了服务生200元酬金。 这里面其实包含了钱以外的价值观念。李嘉诚虽然巨富，但生活俭朴，从不挥霍浪费。他深知亿万资产，都是一元一元挣来的。钱币在他眼中已抽象为一种劳动，而劳动已成为他最重要的生存方式，他的所有财富，都是靠每天20小时以上的劳动堆积起来的。200元酬金，实际上是对劳动的尊重和报答，是不能用金钱衡量的。 富兰克林借书解怨 （尊重别人赢得朋友）

那一刻我感受到了幸福_初中作文

那一刻我感受到了幸福 本文是关于初中作文的那一刻我感受到了幸福，感谢您的阅读！ 每个人民的心中都有一粒幸福的种子，当它拥有了雨水的滋润和阳光的沐浴，它就会绽放出最美丽的姿态。那一刻，我们都能够闻到幸福的芬芳，我们都能够感受到幸福的存在。 在寒假期间，我偶然在授索电视频道，发现(百家讲坛)栏目中大学教授正在解密幸福，顿然引起我的好奇心，我放下了手中的遥控器，静静地坐在电视前，注视着频道上的每一个字，甚至用笔急速记在了笔记本上。我还记得，那位大学教授讲到了一个故事：一位母亲被公司升职到外国工作，这位母亲虽然十分高兴，但却又十分无奈，因为她的儿子马上要面临中考了，她不能撇下儿子迎接中考的挑战，于是她决定拒绝这了份高薪的工作，当有人问她为什么放弃这么好的机会时，她却毫无遗憾地说，纵然我能给予儿子最贵的礼物，优异的生活环境，但我却无当给予他关键时刻的那份呵护与关爱，或许以后的一切会证明我的选择是正确的。听完这样一段故事，我心中有种说不出的感觉，刹那间，我仿拂感觉那身边正在包饺子的妈妈，屋里正在睡觉的爸爸，桌前正在看小说的妹妹给我带来了一种温馨，幸福感觉。正如教授所说的那种解密幸福。就要选择一个明确的目标，确定自已追求的是什么，或许那时我还不能完全诠释幸福。 当幸福悄悄向我走来时，我已慢慢明白，懂得珍惜了。 那一天的那一刻对我来说太重要了，原本以为出差在外的父母早已忘了我的生日，只有妹妹整日算着日子。我在耳边唠叨个不停，没想到当日我失落地回到家中时，以为心中并不在乎生日，可是眼前的一切，让我心中涌现的喜悦，脸上露出的微笑证明我是在乎的。

爸爸唱的英文生日快乐歌虽然不是很动听，但爸爸对我的那份爱我听得很清楚，妈妈为我做的长寿面，我细细的品尝，吃出了爱的味道。妹妹急忙让我许下三个愿望，嘴里不停的唠叨：我知道你的三个愿望是什么?我问：为什么呀!我们是一家人，心连心呀!她高兴的说。 那一刻我才真正解开幸福的密码，感受到了真正的幸福，以前我无法理解幸福，即使身边有够多的幸福也不懂得欣赏，不懂得珍惜，只想拥有更好更贵的，其实幸福比物质更珍贵。 那一刻的幸福就是爱的升华，许多时候能让我们感悟幸福不是名利，物质。而是在血管里涌动着的，漫过心底的爱。 也许每一个人生的那一刻，就是我们幸运的降临在一个温馨的家庭中，而不是降临在孤独的角落里。 家的感觉就是幸福的感觉，幸福一直都存在于我们的身边!

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