Probing the Low-Luminosity XLF in Normal Elliptical Galaxies

Abstract

We present the first low luminosity (LX > 5 - 10 1036 erg s-1) X-ray luminosity functions (XLFs) of low-mass X-ray binaries (LMXBs) determined for two typical old elliptical galaxies, NGC 3379 and NGC 4278. Because both galaxies contain little diffuse emission from hot ISM and no recent significant star formation (hence no high-mass X-ray binary contamination), they provide two of the best homogeneous sample of LMXBs. With 110 and 140 ks Chandra ACIS S3 exposures, we detect 59 and 112 LMXBs within the D25 ellipse of NGC 3379 and NGC 4278, respectively. The resulting XLFs are well represented by a single power-law with a slope (in a differential form) of 1.9 0.1. In NGC 4278, we can exclude the break at LX ~ 5 x 1037 erg s-1 that was recently suggested to be a general feature of LMXB XLFs. In NGC 3379 instead we find a localized excess over the power law XLF at ~4 x 1037 erg s-1, but with a marginal significance of ~1.6s. Because of the small number of luminous sources, we cannot constrain the high luminosity break (at 5 x 1038 erg s-1) found in a large sample of early type galaxies. While the optical luminosities of the two galaxies are similar, their integrated LMXB X-ray luminosities differ by a factor of 4, consistent with the relation between the X-ray to optical luminosity ratio and the globular cluster specific frequency.

18 pages, 6 figures, submitted to ApJ

References in corpus (32)

• The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances
• The Stellar Population Histories of Local Early-Type Galaxies. I. Population Parameters
• The Properties of X-Ray and Optical Light Curves of X-Ray Novae
• Deep Extragalactic X-ray Surveys
• Low mass X-ray binaries as a stellar mass indicator for the host galaxy
• X-ray source populations in galaxies
• The Milky Way in X-rays for an outside observer: Log(N)-Log(S) and Luminosity Function of X-ray binaries from RXTE/ASM data
• The Fall of AGN and the Rise of Star-Forming Galaxies: A Close Look at the Chandra Deep Field X-ray Number Counts
• A Catalogue and Analysis of Local Galaxy Ages and Metallicities
• X-ray Luminosity Function and Total Luminosity of LMXB in Early Type Galaxies
• Chandra X-ray Observations of the X-ray Faint Elliptical Galaxy NGC 4697
• White Dwarf Donors in Ultracompact Binaries: The Stellar Structure of Finite Entropy Objects
• The Galactic Population of Low- and Intermediate-Mass X-ray Binaries
• The Low-Mass X-ray Binary-Globular Cluster connection in NGC 4472
• X-ray Point Sources in The Central Region of M31 as seen by Chandra
• Chandra X-ray Observations of NGC 1316 (Fornax A)
• Chandra Multi-wavelength Project (ChaMP). I. First X-ray Source Catalog
• Intermediate Mass Black Holes in Accreting Binaries: Formation, Evolution and Observational Appearance
• Low Mass X-ray Binaries in 6 Elliptical Galaxies: Connection to Globular Clusters
• Ultracompact Binaries as Bright X-Ray Sources in Elliptical Galaxies
• Chandra Multi-wavelength Project (ChaMP). II. First Results of X-ray Source Properties
• The Low Mass X-ray Binary-Globular Cluster Connection II: NGC 4472 X-ray Source Properties and Source Catalogs
• M31 Globular Cluster X-ray Sources: XMM-Newton and Chandra results
• Imaging Large Scale Structure in the X-ray Sky
• X-ray Binaries and Globular Clusters in Elliptical Galaxies
• The Luminosity Function of X-ray Point Sources in Centaurus A
• Chandra Studies of the X-ray Point Source Luminosity Functions of M31
• The Birthplace of Low-Mass X-ray Binaries: Field Versus Globular Cluster Populations
• X-ray Arc Structures in Chandra Images of NGC5128 (Centaurus A)
• The Diffuse Emission and a Variable ULX in the Elliptical Galaxy NGC 3379
• The Brightest Point X-Ray Sources in Elliptical Galaxies and the Mass Spectrum of Accreting Black Holes
• X-ray luminosity function of low-mass X-ray binaries in galaxies

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• Models for Low-Mass X-Ray Binaries in the Elliptical Galaxies NGC3379 and NGC4278: Comparison with Observations
• Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. I. Chandra Observations
• A Flexible Method of Estimating Luminosity Functions
• Low-mass X-ray binaries in the bulge of the Milky Way
• Luminosity functions of LMXBs in Centaurus A: globular clusters versus the field
• Deep Chandra Monitoring Observations of NGC 3379: Catalog of Source Properties
• The X-ray Luminosity Functions of Field Low Mass X-ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence
• Deep Chandra Monitoring Observations of NGC 4278: Catalog of Source Properties
• Transient Low-Mass X-Ray Binary Populations in Elliptical Galaxies NGC 3379 and NGC 4278
• X-ray Binary Luminosity Function Scaling Relations in Elliptical Galaxies: Evidence for Globular Cluster Seeding of Low-Mass X-ray Binaries in Galactic Fields
• AGN activity and the misaligned hot ISM in the compact radio elliptical NGC4278
• Chandra ACIS Survey of X-ray Point Sources in Nearby Galaxies. II. X-ray Luminosity Functions and Ultraluminous X-ray Sources
• Luminosity Functions and Point Source Properties from Multiple Chandra Observations of M81
• Population synthesis of classical low-mass X-ray binaries in the Galactic Bulge
• Swift-BAT Survey of Galactic Sources: Catalog and Properties of the populations
• The diverse hot gas content and dynamics of optically similar low-mass elliptical galaxies
• A Comprehensive Archival Chandra Search for X-ray Emission from Ultracompact Dwarf Galaxies
• The Luminosity Function of Low Mass X-Ray Binaries in the Globular Cluster System of NGC 1399
• Clues on black hole feedback from simulated and observed X-ray properties of elliptical galaxies
• A deeper look at the X-ray point source population of NGC 4472